The Relationships between Symmetry and Attractiveness and Mating Relevant Decisions and Behavior: A Review
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paper_title: Human pheromones and sexual attraction

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Olfactory communication is very common amongst animals, and since the discovery of an accessory olfactory system in humans, possible human olfactory communication has gained considerable scientific interest. The importance of the human sense of smell has by far been underestimated in the past. Humans and other primates have been regarded as primarily 'optical animals' with highly developed powers of vision but a relatively undeveloped sense of smell. In recent years this assumption has undergone major revision. Several studies indicate that humans indeed seem to use olfactory communication and are even able to produce and perceive certain pheromones; recent studies have found that pheromones may play an important role in the behavioural and reproduction biology of humans. In this article we review the present evidence of the effect of human pheromones and discuss the role of olfactory cues in human sexual behaviour.
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paper_title: Female judgment of male attractiveness and desirability for relationships: Role of waist-to-hip ratio and financial status.

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Two studies were conducted to examine the role of male body shape ( as defined by waist-to-hip ratio [WHR]) in female mate choice. In Study I, college-age women judged normal-weight male figures with WHR in the typical male range as most attractive, healthy, and possessing many positive personal qualities. In Study 2, 18-69-year-old women rated normal-weight male figures with differing WHRs and purported income for casual (having coffee) to most-committed (marriage) relationships. All women, regardless of their age, education level, or family income, rated figures with WHRs in the typical male range and higher financial status more favorably. These findings are explained within an evolutionary mate selection context.
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paper_title: Adaptive significance of female physical attractiveness: Role of waist-to-hip ratio.

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Evidence is presented showing that body fat distribution as measured by waist-to-hip ratio (WHR) is correlated with youthfulness, reproductive endocrinologic status, and long-term health risk in women. Three studies show that men judge women with low WHR as attractive. Study 1 documents that minor changes in WHRs of Miss America winners and Playboy playmates have occurred over the past 30-60 years. Study 2 shows that college-age men find female figures with low WHR more attractive, healthier, and of greater reproductive value than figures with a higher WHR. In Study 3, 25- to 85-year-old men were found to prefer female figures with lower WHR and assign them higher ratings of attractiveness and reproductive potential. It is suggested that WHR represents an important bodily feature associated with physical attractiveness as well as with health and reproductive potential. A hypothesis is proposed to explain how WHR influences female attractiveness and its role in mate selection. Evolutionary theories of human mate selection contend that both men and women select mating partners who enable them to enhance reproductive success. Differential reproductive conditions and physiological constraints in men and women, however, induce different gender-specific sexual and reproductive strategies. In general, a woman can increase her reproductive success by choosing a high-status man who controls resources and, hence, can provide material security to successfully raise
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paper_title: Does Women's Hair Signal Reproductive Potential?

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This study explores the possibility that women's hair signals their reproductive potential. Evolutionary psychology and related approaches are considered as rationales for the belief that women's hair is a signal for mate selection and attraction. A sample of women were approached in public places and surveyed as to their age, hair quality, marital status, hair length, children, and overall health. A significant correlation between hair length and age indicated that younger women tend to have longer hair than older women. Hair quality was correlated with women's health. Consistent with the principle of intersexual selection, the results of this study indicate that hair length and quality can act as a cue to a woman's youth and health and, as such, signify reproductive potential. Future directions for research on women's hair are discussed.
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paper_title: Vocal and visual attractiveness are related in women

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Abstract We investigated the relation between visual and vocal attractiveness in women as judged by men. We recorded 34 women speaking four vowels and measured the peak frequency, the first five harmonic frequencies, the first five formant frequencies and formant dispersion. The women were also photographed (head shot), several body measures were taken and their ages were recorded. The voices were played to male judges who were asked to assess the women's age and vocal attractiveness from the recording. The men were then asked to assess the attractiveness of the photographs. Men were in strong agreement on which was an attractive voice and face; and women with attractive faces had attractive voices. Higher-frequency voices were assessed as being more attractive and as belonging to younger women (the lowest frequency produced is a good indicator of age in women in general). Larger women had lower voices and were judged as having less attractive faces and voices. Taller women had narrower formant dispersion as predicted. The results imply that different measures of attractiveness are in agreement and signal similar qualities, such as female age, body size and possibly hormonal profile. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.
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paper_title: WAIST-TO-HIP RATIO AND ATTRACTIVENESS : REPLICATION AND EXTENSION

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Abstract In several experiments Singh ( Journal of Personality and Social Psychology, 65 , 292–307, 1993a; Human Nature, 4 , 297–321, 1993b; Personality and Individual Differences, 16 , 123–132, 1994; Singh & Luis, Human Nature, 6 , 51–65, 1995) presented evidence that the attractiveness of the female figure is related to the waist-to-hip ratio and the apparent overall body weight. The present paper presents a replication and extension of the Singh studies. Both female and male figures are considered. In addition to different aspects of physical attractiveness, the so called Big Five factors of personality are considered. Both similarities and differences between the Singh studies and the present study are discussed.
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paper_title: Age preferences in mates reflect sex differences in human reproductive strategies.

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Social psychologists have held that when selecting mates women prefer older men and men prefer younger women. In a form of economic exchange based on conventional sex role norms both men and women seek potential partners who are similar to themselves. Behavioral psychologists have proposed an evolutionary model to explain age preferences. The social exchange model does not explain what cross cultural research which is that men and women in other cultures differ in ways that are parallel to gender differences in US society. The evolutionary model submits that men and women pursue distinct reproductive strategies. It also theorizes a more complicated relationship between gender and age preferences than the social exchange model. 2 behavioral psychologists have conducted 6 studies to determine whether the evolutionary model holds true. The hypothesis states that during the early years men prefer women who are only somewhat younger than they are but as they are they prefer women who are considerably younger than they are. On the other hand young women prefer men who are slightly older than they are and this preference does not change much with age. The psychologists examined age preferences in personal advertisements from newspapers in Arizona West Germany the Netherlands and India and in singles advertisements by financially successful US women and men in the Washington D.C. They found the results consistently fit well with the evolutionary model. They also studied marriage statistics from Seattle Washington and Phoenix Arizona which also supported the hypothesis. They conducted a cross-generational analysis using 1923 marriage statistics from Phoenix which indicated consistency across generations. A study of marriages that took place between 1913 and 1939 on the small island of Poro in the Philippines also supported the theory. Thus psychologists should expand previous models of age preferences to incorporate the life history position.
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paper_title: Cross-cultural consensus for waist–hip ratio and women's attractiveness

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In women of reproductive age, a gynoid body fat distribution as measured by the size of waist–hip ratio (WHR) is a reliable indicator of their sex hormone profile, greater success in pregnancy and less risk for major diseases. According to evolutionary mate selection theory, such indicators of health and fertility should be judged as attractive. Previous research has confirmed this prediction. In this current research, we use the same stimulus for diverse racial groups (Bakossiland, Cameroon, Africa; Komodo Island, Indonesia; Samoa; and New Zealand) to examine the universality of relationships between WHR and attractiveness. As WHR is positively correlated with body mass index (BMI), we controlled BMI by using photographs of women who have gone through micrograft surgery for cosmetic reasons. Results show that in each culture participants selected women with low WHR as attractive, regardless of increases or decreases in BMI. This cross-cultural consensus suggests that the link between WHR and female attractiveness is due to adaptation shaped by the selection process.
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paper_title: Evolution and Social Cognition: Contrast Effects as a Function of Sex, Dominance, and Physical Attractiveness

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Previous research indicates that males, compared with females, evaluate their relationships less favorably after exposure to physically attractive members of the other sex. An evolutionary model predicts a converse effect after exposure to opposite-sex individuals high in dominance, which should lead females to evaluate their current relationships less favorably than males. Women and men rated their current relationships after being exposed to opposite-sex targets varying in both dominance and physical attractiveness. Consistent with earlier research, males exposed to physically attractive, as compared with average, targets rated their current relationships less favorably. Males' relationship evaluations were not directly influenced by the targets' dominance, although the effect of physical attractiveness was significant only for men exposed to women low in dominance. However; females' evaluations of their relationships were unaffected by exposure to physically attractive males but were lower after exposu...
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paper_title: The Evolution of Human Sexuality

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An adduct is prepared by heating together, in the presence of an acid catalyst, (1) a perfluoroalkyl alcohol of formula Rf(CH2)n-OH such as perfluoroalkylethyl alcohol; (2) a polyalkylene glycol such as polyethylene glycol having a molecular weight of about 1000; and (3) a poly(alkoxymethyl)melamine such as hexa(methoxymethyl)melamine. These adducts are effective in promoting oil and water repellency and oily soil release from textiles.
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paper_title: Evolutionary Theory and African American Self-Perception: Sex Differences in Body-Esteem Predictors of Self-Perceived Physical and Sexual Attractiveness, and Self-Esteem

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Evolutionary biological theory has been shown to be relevant to an understanding of how individuals assess others' physical and sexual attractiveness. This research used the Body-Esteem Scale and multiple regression to determine if this theory is also relevant to an understanding of self-perceived physical and sexual attractiveness and self-esteem for a sample of 91 African Americans. The hypotheses that regression models of physical and sexual attractiveness would differ within and across sex groups and that models of self-esteem would differ across sex groups in accordance with evolutionary theory were supported. Attributes of the body related to fecundity and successful mothering characteristics predicted for women and attributes of the body related to strength and dominance predicted for men. In addition, attributes of the body dealing with sexual maturity were stronger predictors of sexual attractiveness for women. This research indicates that evolutionary biological theory can provide relevant insig...
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paper_title: "Their ideas of beauty are, on the whole, the same as ours": Consistency and variability in the cross-cultural perception of female physical attractiveness.

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The consistency of physical attractiveness ratings across cultural groups was examined. In Study 1, recently arrived native Asian and Hispanic students and White Americans rated the attractiveness of Asian, Hispanic, Black, and White photographed women. The mean correlation between groups in attractiveness ratings was r =.93. Asians, Hispanics, and Whites were equally influenced by many facial features, but Asians were less influenced by some sexual maturity and expressive features. In Study 2, Taiwanese attractiveness ratings correlated with prior Asian, Hispanic, and American ratings, mean r =.91. Supporting Study 1, the Taiwanese also were less positively influenced by certain sexual maturity and expressive features. Exposure to Western media did not influence attractiveness ratings in either study. In Study 3, Black and White American men rated the attractiveness of Black female facial photos and body types. Mean facial attractiveness ratings were highly correlated (r = .94), but as predicted Blacks and Whites varied in judging bodies
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paper_title: A cross-cultural investigation of the role of foot size in physical attractiveness

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Disparate cultural practices suggest that small foot size may contribute to female attractiveness. Two hypotheses potentially explain such a pattern. Sexual dimorphism in foot size may lead observers to view small feet as feminine and large feet as masculine. Alternately, because small female feet index both youth and nulliparity, evolution may have favored a male preference for this attribute in order to maximize returns on male reproductive investment. Whereas the observational hypothesis predicts symmetrical polarizing preferences, with small feet being preferred in women and large feet being preferred in men, the evolutionary hypothesis predicts asymmetrical preferences, with the average phenotype being preferred in men. Using line drawings that varied only in regard to relative foot size, we examined judgments of attractiveness in nine cultures. Small foot size was generally preferred for females, while average foot size was preferred for males. These results provide preliminary support for the hypothesis that humans possess an evolved preference for small feet in females.
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paper_title: Dominance and heterosexual attraction

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Four experiments examined the relation between behavioral expressions of dominance and the heterosexual attractiveness of males and females. Predictions concerning the relation between dominance and heterosexual attraction were derived from a consideration of sex role norms and from the comparative biological literature. All four experiments indicated an interaction between dominance and sex of target. Dominance behavior increased the attractiveness of males, but had no effect on the attractiveness of females. The third study indicated that the effect did not depend on the sex of the rater or on the sex of those with whom the dominant target interacted. The fourth study showed that the effect was specific to dominance as an independent variable and did not occur for related constructs (aggressive or domineering). This study also found that manipulated dominance enhanced only a male's sexual attractiveness and not his general Usability. The results were discussed in terms of potential biological and cultural causal mechanisms. Concepts that refer to an individual's relative position in a social hierarchy occupy prominent positions in current models of personality and social behavior (Edelmarv & Omark, 1973; Hogan, 1979,1982;StrayerS his analysis of personality descriptions in different language groups indicates that dominance-submission is a universal lexical feature of human languages. The research reported here concerns the relation between behavioral expressions of dominance and the sexual attractiveness of males and females. Specific relations between dominance and attraction are predicted both by sociobiological theories that emphasize evolutionarily determined behavior tendencies and by scciocultural theories that emphasize socialization practices and sex role expectations.
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paper_title: Height and reproductive success in a cohort of british men

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Two recent studies have shown a relationship between male height and number of offspring in contemporary developed-world populations. One of them argues as a result that directional selection for male tallness is both positive and unconstrained. This paper uses data from a large and socially representative national cohort of men who were born in Britain in March 1958. Taller men were less likely to be childless than shorter ones. They did not have a greater mean number of children. If anything, the pattern was the reverse, since men from higher socioeconomic groups tended to be taller and also to have smaller families. However, clear evidence was found that men who were taller than average were more likely to find a long-term partner, and also more likely to have several different long-term partners. This confirms the finding that tall men are considered more attractive and suggests that, in a noncontracepting environment, they would have more children. There is also evidence of stabilizing selection, since extremely tall men had an excess of health problems and an increased likelihood of childlessness. The conclusion is that male tallness has been selected for in recent human evolution but has been constrained by developmental factors and stabilizing selection on the extremely tall.
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paper_title: What do women want? Facialmetric assessment of multiple motives in the perception of male facial physical attractiveness

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The multiple motive hypothesis of physical attractiveness suggests that women are attracted to men whose appearances elicit their nurturant feelings, who appear to possess sexual maturity and dominance characteristics, who seem sociable, approacheable, and of high social status. Those multiple motives may cause people to be attracted to individuals who display an optimal combination of neotenous, mature, and expressive facial features, plus desirable grooming attributes. Three quasi-experiments demonstrated that men who possessed the neotenous features of large eyes, the mature features of prominent cheekbones and a large chin, the expressive feature of a big smile, and high-status clothing were seen as more attractive than other men. Further supporting the multiple motive hypothesis, the 2nd and 3rd studies indicated that impressions of attractiveness had strong relations with selections of men to date and to marry but had a curvilinear relation with perceptions of a baby face vs. a mature face.
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paper_title: Is thin really beautiful and good? Relationship between waist-to-hip ratio (WHR) and female attractiveness

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Abstract Two studies were conducted to determine the relative role played by overall body fat and body fat distribution as indicated by the measure of waist-to-hip ratio (WHR) in determining female perceived attractiveness and associated personality attributes. Contrary to popular belief, thin female figures were neither perceived most attractive nor assigned many desirable personality traits, except youthfulness. The measure of body fat distribution, the WHR, was found to be the critical variable associated with attractiveness. Normal weight female figures with low WHR were judged to be most attractive and were assigned many desirable qualities.
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paper_title: Mating context and menstrual phase affect women's preferences for male voice pitch

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Abstract Fundamental frequency ( F 0 ) is the vocal acoustic parameter closest to what we perceive as pitch. Men speak at a lower F 0 than do women, even controlling for body size. Although the developmental and anatomical reasons for this sex difference are known, the evolutionary reasons are not. By examining fertility-related variation in women's preferences for men's voices, the present study tests the hypothesis that female choice for good genes influenced the evolution of male voice pitch (VP). Unlike previous correlational studies that did not consider the effects of menstrual phase and mating context on women's preferences for male VP, the present study includes these variables and utilizes experimental pitch (P) manipulations. Results indicate that low VP is preferred mainly in short-term mating contexts rather than in long-term, committed ones, and this mating context effect is greatest when women are in the fertile phase of their ovulatory cycles. Moreover, lower male F 0 correlated with higher self-reported mating success. These findings are consistent with the hypothesis that an association between low male VP and heritable fitness led to the evolution of the observed patterns in women's P preferences and men's mating success and that these patterns influenced the evolution of low VP in men. However, alternative explanations are considered.
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paper_title: Reproductive strategies and disease susceptibility: an evolutionary viewpoint.

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Arguments about which constitutes the 'weaker sex' notwithstanding, sex differences in mortality and disease susceptibility have been noted in many species of animals, including humans. In this article, Marlene Zuk examines the possible reasons for these differences, relating them to reproductive strategies, and suggests how they may have resulted from selective pressures.
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paper_title: The associations between obesity, adipose tissue distribution and disease.

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Recent research has shown the marked differences in association with disease between obesity localized to the abdominal respectively to the gluteal-femoral regions. In this review systematic analyses were performed of the associations between obesity (body mass index, BMI) or abdominal obesity (increased waist-over-hip circumference ratio, WHR) on the one hand, and a number of disease end points, and their risk factors, as well as other factors on the other, WHR was associated with cardiovascular disease, premature death, stroke, non-insulin-dependent diabetes mellitus and female carcinomas. In contrast, BMI tended to be negatively correlated to cardiovascular disease, premature death, and stroke, but positively to diabetes. The established risk factors for these end points were found to correlate to WHR, while this was often not the case with BMI. BMI was positively correlated only to insulin, triglycerides and blood pressure. Together with diabetes mellitus, this seems to constitute a metabolic group of conditions which are thus associated with BMI. Androgens (in women), and perhaps cortisol, seem to be positively, and progesterone negatively correlated to WHR. The WHR was also positively associated with sick leave, several psychological maladjustments, psychosomatic and psychiatric disease. Attempts were made to interpret these findings. In a first alternative an elevation of FFA concentration, produced from abdominal adipose tissue, was considered to be the trigger factor for the pathologic aberrations associated with abdominal distribution of body fat. When obesity is added, the metabolic aberrations may be exaggerated. In a second alternative adrenal cortex hyperactivity was tested as the cause. When combined with the FFA hypothesis, this might explain many but not all of the findings. It seems possible to produce an almost identical syndrome in primates by defined experimental stress. Women with high WHR were found to have a number of symptoms of poor coping to stress. It was therefore suggested that part of the background to this syndrome might be a hypothalamic arousal syndrome developing with stress. It was concluded that obesity and abdominal distribution of adipose tissue constitute two separate entities with different pathogenesis, clinical consequences and probably treatment.
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paper_title: Parasites, Bright Males, and the Immunocompetence Handicap

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It has been argued that females should be able to choose parasite-resistant mates on the basis of the quality of male secondary sexual characters and that such signals must be costly handicaps in order to evolve. To a large extent, handicap hypotheses have relied on energetic explanations for these costs. Here, we have presented a phenomenological model, operating on an intraspecific level, which views the cost of secondary sexual development from an endocrinological perspective. The primary androgenic hormone, testosterone, has a dualistic effect; it stimulates development of characteristics used in sexual selection while reducing immu- nocompetence. This "double-edged sword" creates a physiological trade-off that influences and is influenced by parasite burden. We propose a negative-feedback loop between signal intensity and parasite burden by suggesting that testosterone-dependent signal intensity is a plastic re- sponse. This response is modified in accordance with the competing demands of the potential costs of parasite infection versus that of increased reproductive success afforded by exaggerated signals. We clarify how this trade-off is intimately involved in the evolution of secondary sexual characteristics and how it may explain some of the equivocal empirical results that have surfaced in attempts to quantify parasite's effect on sexual selection.
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paper_title: The mystery of female beauty

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Evolutionary psychology suggests that a woman's sexual attractiveness might be based on cues of reproductive potential. It has been proposed that a major determinant of physical attractiveness is the ratio between her waist and hip measurements (the waist-to-hip ratio, or WHR): for example, a woman with a curvaceous body and a WHR of 0.7 is considered to be optimally attractive1,2,3, presumably because this WHR is the result of a fat distribution that maximizes reproductive potential4. It follows that the preference for a curvaceous body shape in women should be universal among men and not be culturally based, because natural selection presumably favours cues indicative of the most fertile body shape.
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paper_title: Female health, attractiveness, and desirability for relationships: Role of breast asymmetry and waist-to-hip ratio

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Abstract Fluctuating asymmetry (FA) of ordinarily bilaterally symmetrical traits in humans has been proposed to indicate developmental anomaly. Recent research has shown that individuals with minimal FA are judged to be attractive, and preferred as sexual partners (Thornhill and Gangestad 1993). Waist-to-hip ratios (WHR) have been also shown to reflect health and reproductive capability of woman and those with low WHRs are judged more attractive and healthy (Singh 1993a,b). The present study examines the relative roles of WHR and FA in female breasts in judgments of female attractiveness, health, and desirability for short-term and long-term relationships. Male college students were asked to judge attractiveness of female figures that differed in WHR (high and low) and breast symmetry (none, low, or high). In the first test, paired comparison method was used in which each figure was paired one at a time with all other figures. In the second test, subjects examined all figures simultaneously, estimated their age, and rated each figure for attractiveness, feminine looks, health, overall degree of body symmetry, and willingness to engage in short- and long-term relationship. Results from both tests show that figures with low WHRs were judged to be more attractive than figures with high WHRs, regardless of their degree of breast asymmetry. The figure with low WHR and symmetrical breasts was judged to be most attractive and youngest of all other figures. It appears that men use both WHR and breast asymmetry in judging attractiveness and being willing to develop romantic relationships. It is proposed that WHR and breast asymmetry may signal different aspects of overall female mate quality.
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paper_title: Adaptive preferences for leg length in a potential partner

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It has been shown that height is one of the morphological traits that influence a person's attractiveness. To date, few studies have addressed the relationship between different components of height and physical attractiveness. Here, we study how leg length influences attractiveness in men and women. Stimuli consisted of seven different pictures of a man and seven pictures of a woman in which the ratio between leg length and height was varied from the average phenotype by elongating and shortening the legs. One hundred men and 118 women were asked to assess the attractiveness of the silhouettes using a seven-point scale. We found that male and female pictures with shorter than average legs were perceived as less attractive by both sexes. Although longer legs appeared to be more attractive, this was true only for the slight (5%) leg length increase; excessively long legs decreased body attractiveness for both sexes. Because leg length conveys biological quality, we hypothesize that such preferences reflect the workings of evolved mate-selection mechanisms. Short and/or excessively long legs might indicate maladaptive biological conditions such as genetic diseases, health problems, or weak immune responses to adverse environmental factors acting during childhood and adolescence.
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paper_title: Body weight, waist-to-hip ratio, breasts, and hips: Role in judgments of female attractiveness and desirability for relationships

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Abstract Morphological features such as overall body fat, body fat distribution, as measured by waist-to-hip ratio, breast size, and hip width have been proposed to influence female attractiveness and desirability. To determine how the variations of these morphological features interact and affect the judgment of female age, attractiveness, and desirability for romantic relationships, two studies were conducted. In Study 1, college-age men rated female figures differing in body weight, waist-to-hip ratio, and breast size for age, attractiveness, health, and desirability for short-and long-term relationships. Female figures with slender bodies, low waist-to-hip ratios, and large brasts were rated as most attractive, feminine looking, healthy, and desirable for casual and long-term romantic relationships. In Study 2, female figures with similar body weight and waist-to-hip ratios but differing hip widths and breast sizes were rated for the same attributes as in Study 1. Female figures with large breasts and narrow hips were rated as most youthful, attractive, and desirable for casual and long-term romantic relationships. It seems that larger body size, a high waist-to-hip ratio, and larger hips make the female figure appear older, unattractive, and less desirable for engaging in romantic relationships. Discussion focuses on the functional significance of interactions among various morphological features in determining female attractiveness.
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paper_title: Pupillometry: A sexual selection approach

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We attempted to clarify prior reported discrepancies between males judging females and females judging males in the attraction value of pupil size. Our hypothesis was that attraction values of pupil size will be described by an interaction effect, such that males will be most attracted by large pupils in females and females by medium size pupils in males. The rationale for the hypothesis was that the reproductive strategies of males are best served by unequivocal female sexual interest and arousal, whereas the strategies of females will predispose them to favor more moderate sexual attentions. As expected, the relationship of attraction to pupil size was positive and linear for males viewing females. Females, however, rather than showing the predicted inverted U function, showed consistent preferences for either medium or large pupils in males. Further investigation revealed that females attracted by large pupils also reported preferences for proverbial bad boys as dating partners. Analogous findings in the literature on female romantic partner preferences are discussed.
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paper_title: Men's voices and women's choices

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I investigated the relationship between male human vocal characteristics and female judgements about the speaker. Thirty-four males were recorded uttering five vowels and measures were taken, from power spectrums, of the first five harmonic frequencies, overall peak frequency and formant frequencies (emphasized, resonance, frequencies within the vowel). Male body measures were also taken (age, weight, height, and hip and shoulder width) and the men were asked whether they had chest hair. The recordings were then played to female judges, who were asked to rate the males' attractiveness, age, weight and height, and to estimate the muscularity of the speaker and whether he had a hairy chest. Men with voices in which there were closely spaced, low-frequency harmonics were judged as being more attractive, older and heavier, more likely to have a hairy chest and of a more muscular body type. There was no relationship between any vocal and body characteristic. The judges' estimates were incorrect except for weight. They showed extremely strong agreement on all judgements. The results imply that there could be sexual selection through female choice for male vocal characteristics, deeper voices being preferred. However, the function of the preference is unclear given that the estimates were generally incorrect.
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paper_title: Women's height, reproductive success and the evolution of sexual dimorphism in modern humans

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Recent studies have shown that, in contemporary populations, tall men have greater reproductive success than shorter men. This appears to be due to their greater ability to attract mates. To our knowledge, no comparable results have yet been reported for women. This study used data from Britain's National Child Development Study to examine the life histories of a nationally representative group of women. Height was weakly but significantly related to reproductive success. The relationship was U-shaped, with deficits at the extremes of height. This pattern was largely due to poor health among extremely tall and extremely short women. However, the maximum reproductive success was found below the mean height for women. Thus, selection appears to be sexually disruptive in this population, favouring tall men and short women. Over evolutionary time, such a situation tends to maintain sexual dimorphism. Men do not use stature as a positive mate-choice criterion as women do. It is argued that there is good evolutionary reason for this, because men are orientated towards cues of fertility, and female height, being positively related to age of sexual maturity, is not such a cue.
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paper_title: Hairstyle as an adaptive means of displaying phenotypic quality

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Although facial features that are considered beautiful have been investigated across cultures using the framework of sexual selection theory, the effects of head hair on esthetic evaluations have rarely been examined from an evolutionary perspective. In the present study the effects of six hair-styles (short, medium-length, long, disheveled, knot [hair bun], unkempt) on female facial attractiveness were examined in four dimensions (femininity, youth, health, sexiness) relative to faces without visible head hair (“basic face”). Three evolutionary hypotheses were tested (covering hypothesis, healthy mate theory, and good genes model); only the good genes model was supported by our data. According to this theory, individuals who can afford the high costs of long hair are those who have good phenotypic and genetic quality. In accordance with this hypothesis, we found that only long and medium-length hair had a significant positive effect on ratings of women’s attractiveness; the other hairstyles did not influence the evaluation of their physical beauty. Furthermore, these two hairstyles caused a much larger change in the dimension of health than in the rest of the dimensions. Finally, male raters considered the longer-haired female subjects’ health status better, especially if the subjects were less attractive women. The possible relationships between facial attractiveness and hair are discussed, and alternative explanations are presented.
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paper_title: Ethnic and gender consensus for the effect of waist-to-hip ratio on judgment of women's attractiveness

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The western consensus is that obese women are considered attractive by Afro-Americans and by many societies from nonwestern developing countries. This belief rests mainly on results of nonstandardized surveys dealing only with body weight and size, ignoring body fat distribution. The anatomical distribution of female body fat as measured by the ratio of waist to hip circumference (WHR) is related to reproductive age, fertility, and risk for various major diseases and thus might play a role in judgment of attractiveness. Previous research (Singh 1993a, 1993b) has shown that in the United States Caucasian men and women judge female figures with feminine WHRs as attractive and healthy. To investigate whether young Indonesian and Afro-American men and women rate such figures similarly, female figures representing three body sizes (underweight, normal weight, and overweight) and four WHRs (two feminine and two masculine) were used. Results show that neither Indonesian nor Afro-American subjects judge overweight figures as attractive and healthy regardless of the size of WHR. They judged normal weight figures with feminine WHRs as most attractive, healthy, and youthful. The consensus on women’s attractiveness among Indonesian, Afro-American, and U.S. Caucasian male and female subjects suggests that various cultural groups have similar criteria for judging the ideal woman’s shape.
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paper_title: Evolutionary Theory and Self-perception: Sex Differences in Body Esteem Predictors of Self-perceived Physical and Sexual Attractiveness and Self-Esteem

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Responses to the body esteem scale (Franzoi & Shields, 1984) and multiple regression were used to determine if evolutionary biological theory is relevant to an understanding of self-perceived physical and sexual attractiveness and selfesteem and to determine if physical and sexual attractiveness are the same construct. It was hypothesized that regression models of physical and sexual attractiveness would differ within and across sex groups and that models of self-esteem would differ across sex groups in accordance with evolutionary theory. These hypotheses were supported. Attributes of the body related to fecundity and successful mothering characteristics predicted for women and attributes of the body related to strength and dominance predicted for men. In addition, attributes of the body dealing with sexual maturity were stronger predictors of sexual attractiveness. Physical and sexual attractiveness are not the same constructs. This research indicates that evolutionary bological theory can provide relev...
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paper_title: FLUCTUATING ASYMMETRY: AN EPIGENETIC MEASURE OF STRESS

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(1) Fluctuating asymmetry (FA) is a useful trait for monitoring stress in the laboratory and in natural environments. (2) Both genomic and environmental changes can increase FA which represents a deterioration in developmental homeostasis apparent in adult morphology. Genetic perturbations include intense directional selection and certain specific genes. Environmental perturbations include temperature extremes in particular, protein deprivation, audiogenic stress, and exposure to pollutants. (3) There is a negative association between FA and heterozygosity in a range of taxa especially fish, a result consistent with FA being a measure of fitness. (4) Scattered reports on non-experimental populations are consistent with experiments under controlled laboratory conditions. FA tends to increase as habitats become ecologically marginal; this includes exposure to environmental toxicants. (5) In our own species, FA of an increasing range of traits has been related to both environmental and genomic stress. (6) Domestication increases FA of the strength of homologous long bones of vertebrate species due to a relaxation of natural selection. (7) FA levels are paralleled by the incidence of skeletal abnormalities in stressful environments. (8) Increased FA is a reflection of poorer developmental homeostasis at the molecular, chromosomal and epigenetic levels.
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paper_title: Fluctuating Asymmetry: Measurement, Analysis, Patterns

paper_content:

With these words Darwin opened a brief paragraph citing observations antithetical to his supposition: anecdotal reports of the inheritance of characters missing from one side of the body. His initial hunch, however, has stood the test of time: Genetic studies have confirmed that where only small, random deviations from bilateral symmetry exist, the deviations in a particular direction have little or no measurable heritability (17, 47, 51, 65a, 73a, 74, 91). The genetic basis of bilateral symmetry thus appears to differ fundamentally from that of virtually all other morphological features. Why, then, all the recent (and not so recent) interest in such minor, nondirectional deviations from bilateral symmetry [fluctuating asymmetry (FA); 60 cited in 99]? Four reasons. First, FA relates in a curious way to what is perhaps the major unsolved general problem in modem biology: the orderly expression of genotypes as complex, three-dimensional phenotypes. As was emphasized in a flurry of activity in the mid to late 1950s, and many times since, FA provides an appealing measure of 'developmental noise,' or minor environmentally induced departures from some ideal developmental program (101). Its appeal derives from an a priori knowledge of the ideal: perfect bilateral symmetry. For unilateral characters, the ideal is rarely known (but see 1, 2, and 59 for one possible approach). A second reason for interest in
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paper_title: Patterns of fluctuating asymmetry in avian feather ornaments: implications for models of sexual selection

paper_content:

Extravagant secondary sexual characters, i.e. sexual ornaments, are exaggerated, often bilaterally symmetrical traits of great intricacy of design. The full expression of such traits is likely to be very costly and close to the limits of production. Any kind of environmental stress is therefore more likely to affect the expression of ornaments than that of any other morphological trait not subjected to strong directional selection. One measure of the ability of individuals to produce extravagant sexual traits is their degree of fluctuating asymmetry. This occurs when symmetry is the normal state and there is no tendency for the trait on one side of the body to have larger character values than that on the other. The degree of fluctuating asymmetry has been shown to reflect the ability of individuals to cope with a wide array of environmental stress (review in Parsons (1990)). We predicted that sexual ornaments should show a larger degree of fluctuating asymmetry than other morphological traits or than homologous traits in non-ornamented species. If ornaments honestly indicate the quality of individuals, high quality individuals should develop little asymmetry and large traits. Thus, we predicted a general negative relation between the degree of asymmetry and the size of ornaments. This should not be the case for other traits or for homologous traits in conspecific females or in either sex of monomorphic species. We tested these predictions on elaborate feather ornaments in birds, as these have been shown to be used as cues during female choice. We made pairwise comparisons between males and females of ornamented species and between males of ornamented and of non-ornamented, confamilial species. Sexual ornaments showed both a larger absolute and relative degree of fluctuating asymmetry than did wing length or did traits homologous to the feather ornament in females and in males of non-ornamented species. The degree of fluctuating asymmetry for tail ornaments generally showed a negative relation with the size of the ornament, whereas that was not the case for wing length or for traits homologous to the feather ornament in females and in males of non-ornamented species. The large degree of fluctuating asymmetry in ornaments and the negative relation between ornament size and degree of asymmetry suggest that fluctuating asymmetry in ornaments reliably reflects male phenotypic quality.
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paper_title: Human (Homo sapiens) facial attractiveness and sexual selection: the role of symmetry and averageness.

paper_content:

We hypothesized from the parasite theory of sexual selection that men (Homo sapiens) would prefer averageness and symmetry in women's faces, that women would prefer averageness and symmetry in men's faces, and that women would prefer largeness (not averageness) of the secondary sexual traits of men's faces. We generated computer images of men's and women's faces and of composites of the faces of each sex, and then had men and women rate opposite-sex faces for 4 variables (attractive, dominant, sexy, and healthy). Symmetry, averageness, and the sizes of facial features were measured on the computerized faces. The hypotheses were supported, with the exception of the hypothesized effects of averageness of female and male faces on attractiveness ratings. This is the first study to show that facial symmetry has a positive influence on facial attractiveness ratings. Although adult facial attractiveness ratings are replicable, even cross-culturally (see reviews and discussions in Jones & Hill, 1993, and Langlois & Roggman, 1990), there has been considerable controversy around attempts to identify in research the facial features that actually cause faces to be judged attractive or unattractive. As discussed by Langlois and Roggman, studies of individual facial features (e.g., nose size) often have yielded inconsistent results between studies. Faces created by combining individual faces into composites have been shown to be more attractive than the individual faces, which is felt to be a preference for average facial features (Langlois & Roggman, 1990; Symons, 1979). Averageness effaces can be calculated metrically or constructed photogrammetrically. Gallon (1879) constructed composites of individual pictures with the photographic method of simply projecting them one over the other on a negative. According to Gallon, this method "enables us to obtain with mechanical precision a generalized picture; one that represents no man in particular, but portrays an imaginary figure possessing the average features of any given group of man" (1879, p. 341). Indeed, Treu (1914) had the impression that these composites are "singularly beautiful" (p. 441). However, as Alley and Cunningham (1991; see also Benson & Perrett, 1991) pointed out, composites are also more symmetrical and rather free of
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paper_title: Study of genetic variance in the fluctuating asymmetry of anthropometrical traits

paper_content:

SummaryWe have studied the fluctuating asymmetry (FA) of 8 bilateral morphometric traits in two-parent families, comprising 216 families with one newborn baby, and 60 families with two children (age range 5–18 years). Heritability was assessed by: (1) multiple regression analyses of the children's measurements on the mother's and father's measurements; (2) midparent-child regressions; and (3) sibling correlations. The extent of genetic determination of individual FA measurements was generally low, albeit statistically significant in some cases. However, even these correlations were inconsistent between samples and relatives. However, the mean FA values for all 8 studied traits showed positive and significant correlation between parents and children in two samples and in total. Additive genetic variance, calculated from multiple regression analyses and midparent-child correlations, was estimated to be between 0·25–0·30. Three multiple regressions (two for the separate group and one for the total sample) yi...
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paper_title: Facial attractiveness, developmental stability, and fluctuating asymmetry

paper_content:

Abstract Despite robust cross-cultural reliability of human facial attractiveness ratings, research on facial attractiveness has only superficially addressed the connection between facial attractiveness and the history of sexual selection in Homo sapiens . There are reasons to believe that developmental stability and phenotypic quality are related. Recent studies of nonhuman animals indicate that developmental stability, measured as fluctuating asymmetry in generally bilateral symmetrical traits, is predictive of performance in sexual selection: Relatively symmetrical males are advantaged under sexual selection. This pattern is suggested by our study of facial attractiveness and fluctuating asymmetry in seven bilateral body traits in a student population. Overall, facial attractiveness negatively correlated with fluctuating asymmetry; the relation for men, but not for women, was statistically reliable. Possible confounding factors were controlled for in the analysis.
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paper_title: Attractiveness of facial averageness and symmetry in non-Western cultures: In search of biologically based standards of beauty

paper_content:

Averageness and symmetry are attractive in Western faces and are good candidates for biologically based standards of beauty. A hallmark of such standards is that they are shared across cultures. We examined whether facial averageness and symmetry are attractive in non-Western cultures. Increasing the averageness of individual faces, by warping those faces towards an averaged composite of the same race and sex, increased the attractiveness of both Chinese (experiment 1) and Japanese (experiment 2) faces, for Chinese and Japanese participants, respectively. Decreasing averageness by moving the faces away from an average shape decreased attractiveness. We also manipulated the symmetry of Japanese faces by blending each original face with its mirror image to create perfectly symmetric versions. Japanese raters preferred the perfectly symmetric versions to the original faces (experiment 2). These findings show that preferences for facial averageness and symmetry are not restricted to Western cultures, consistent with the view that they are biologically based. Interestingly, it made little difference whether averageness was manipulated by using own-race or other-race averaged composites and there was no preference for own-race averaged composites over other-race or mixed-race composites (experiment 1). We discuss the implications of these results for understanding what makes average faces attractive. We also discuss some limitations of our studies, and consider other lines of converging evidence that may help determine whether preferences for average and symmetric faces are biologically based.
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paper_title: Symmetry, averageness, and feature size in the facial attractiveness of women.

paper_content:

Female facial attractiveness was investigated by comparing the ratings made by male judges with the metric characteristics of female faces. Three kinds of facial characteristics were considered: facial symmetry, averageness, and size of individual features. The results suggested that female face attractiveness is greater when the face is symmetrical, is close to the average, and has certain features (e.g., large eyes, prominent cheekbones, thick lips, thin eyebrows, and a small nose and chin). Nevertheless, the detrimental effect of asymmetry appears to result solely from the fact that an asymmetrical face is a face that deviates from the norm. In addition, a factor analysis indicated that averageness best accounts for female attractiveness, but certain specific features can also be enhancing.
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paper_title: Human (Homo sapiens) facial attractiveness and sexual selection: the role of symmetry and averageness.

paper_content:

We hypothesized from the parasite theory of sexual selection that men (Homo sapiens) would prefer averageness and symmetry in women's faces, that women would prefer averageness and symmetry in men's faces, and that women would prefer largeness (not averageness) of the secondary sexual traits of men's faces. We generated computer images of men's and women's faces and of composites of the faces of each sex, and then had men and women rate opposite-sex faces for 4 variables (attractive, dominant, sexy, and healthy). Symmetry, averageness, and the sizes of facial features were measured on the computerized faces. The hypotheses were supported, with the exception of the hypothesized effects of averageness of female and male faces on attractiveness ratings. This is the first study to show that facial symmetry has a positive influence on facial attractiveness ratings. Although adult facial attractiveness ratings are replicable, even cross-culturally (see reviews and discussions in Jones & Hill, 1993, and Langlois & Roggman, 1990), there has been considerable controversy around attempts to identify in research the facial features that actually cause faces to be judged attractive or unattractive. As discussed by Langlois and Roggman, studies of individual facial features (e.g., nose size) often have yielded inconsistent results between studies. Faces created by combining individual faces into composites have been shown to be more attractive than the individual faces, which is felt to be a preference for average facial features (Langlois & Roggman, 1990; Symons, 1979). Averageness effaces can be calculated metrically or constructed photogrammetrically. Gallon (1879) constructed composites of individual pictures with the photographic method of simply projecting them one over the other on a negative. According to Gallon, this method "enables us to obtain with mechanical precision a generalized picture; one that represents no man in particular, but portrays an imaginary figure possessing the average features of any given group of man" (1879, p. 341). Indeed, Treu (1914) had the impression that these composites are "singularly beautiful" (p. 441). However, as Alley and Cunningham (1991; see also Benson & Perrett, 1991) pointed out, composites are also more symmetrical and rather free of
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paper_title: Facial Asymmetry and Attractiveness Judgment in Developmental Perspective

paper_content:

This study examined the role of facial symmetry in the judgment of physical attractiveness. Four experiments investigated people's preference for either somewhat asymmetrical portraits or their symmetrical chimeric composites when presented simultaneously. Experiment 1 found a higher selection rate for symmetrical faces with neutral expression for portraits of old people, and Experiment 2 indicated this may be because symmetry serves as cue for youth in old age. In Experiments 3 and 4 participants examined portraits with emotional expressions. Experiment 3 found a higher selection rate for asymmetrical faces, and Experiment 4 indicated this may be because observers perceived them as more genuine and natural. This study suggests that the low degree of facial asymmetry found in normal people does not affect attractiveness ratings (except for old age), probably because observers are not tuned to perceive it.
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paper_title: Symmetry, sexual dimorphism in facial proportions and male facial attractiveness

paper_content:

Facial symmetry has been proposed as a marker of developmental stability that may be important in human mate choice. Several studies have demonstrated positive relationships between facial symmetry and attractiveness. It was recently proposed that symmetry is not a primary cue to facial attractiveness, as symmetrical faces remain attractive even when presented as half faces (with no cues to symmetry). Facial sexual dimorphisms ('masculinity') have been suggested as a possible cue that may covary with symmetry in men following data on trait size/symmetry relationships in other species. Here, we use real and computer graphic male faces in order to demonstrate that (i) symmetric faces are more attractive, but not reliably more masculine than less symmetric faces and (ii) that symmetric faces possess characteristics that are attractive independent of symmetry, but that these characteristics remain at present undefined.
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paper_title: Facial symmetry and judgements of attractiveness, health and personality

paper_content:

Bilateral symmetry of physical traits is thought to reflect an individual’s phenotypic quality, especially their ability to resist environmental perturbations during development. Therefore, facial symmetry may signal the ability of an individual to cope with the challenges of their environment. Studies concerning the relationship between symmetry and attractiveness lead to the conclusion that preferences for symmetric faces may have some adaptive value. We hypothesized that if symmetry is indeed indicative of an individual’s overall quality, faces high in symmetry should receive higher ratings of attractiveness and health, but also be perceived as demonstrating certain positive personality attributes. College students’ attributions of a set of 20 female faces varying in facial symmetry were recorded. As predicted, faces high in symmetry received significantly higher ratings of attractiveness, health, and certain personality attributes (i.e., sociable, intelligent, lively, self-confident, balanced). Faces low in symmetry were rated as being more anxious. These differences were not caused by an attractiveness stereotype. The present results lend further support to the notions that (i) facial symmetry is perceived as being attractive, presumably reflecting health certification
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paper_title: Evidence against perceptual bias views for symmetry preferences in human faces

paper_content:

Symmetrical human faces are attractive. Two explanations have been proposed to account for symmetry preferences: (i) the evolutionary advantage view, which posits that symmetry advertises mate quality and (ii) the perceptual bias view, which posits that symmetry preferences are a consequence of greater ease of processing symmetrical images in the visual system. Here, we show that symmetry preferences are greater when face images are upright than when inverted. This is evidence against a simple perceptual bias view, which suggests symmetry preference should be constant across orientation about a vertical axis. We also show that symmetry is preferred even in familiar faces, a finding that is unexpected by perceptual bias views positing that symmetry is only attractive because it represents a familiar prototype of that particular class of stimuli.
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paper_title: Facial attractiveness signals different aspects of “quality” in women and men

paper_content:

We explored the relationships between facial attractiveness and several variables thought to be related to genotypic and phenotypic quality in humans (namely fluctuating asymmetry (FA), body mass index (BMI), health, age). To help resolve some controversy around previous studies, we used consistent measurement and statistical methods and relatively large samples of both female (n = 94) and male (n = 95) subjects (to be evaluated and measured), and female (n = 226) and male (n = 153) viewers (to rate attractiveness). We measured the asymmetry of 22 traits from three trait families (eight facial, nine body and five fingerprint traits) and constructed composite asymmetry indices of traits showing significant repeatability. Facial attractiveness was negatively related to an overall asymmetry index in both females and males, with almost identical slopes. Female facial attractiveness was best predicted by BMI and past health problems, whereas male facial attractiveness was best predicted by the socioeconomic status (SES) of their rearing environment. Composite FA indices accounted for a small ( < 4%) but usually significant percentage of the variation in facial attractiveness in both sexes, when factors related to asymmetry were controlled statistically. We conclude that, although facial attractiveness is negatively related to developmental instability (as measured by asymmetry), attractiveness also signals different aspects of ‘‘quality’’ in the two sexes, independent of FA. D 2001 Elsevier Science Inc. All rights reserved.
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paper_title: Fluctuating asymmetry and sexual selection.

paper_content:

Behavioral ecologists are being attracted to the study of within-individual morphological variability, manifested in random deviations from bilateral symmetry, as a means of ascertaining the stress susceptibility of developmental regulatory mechanisms. Several early successes Indicate that incorporating measures of symmetry into sexual-selection studies may help link individual sexual success to a basic component of viability - developmental stability.
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paper_title: Fluctuating asymmetry: a biological monitor of environmental and genomic stress

paper_content:

Increased fluctuating asymmetry (FA) of morphological traits occurs under environmental and genomic stress. Such conditions will therefore lead to a reduction in developmental homeostasis. Based upon temperature extreme experiments, relatively severe stress is needed to increase FA under field conditions. Increasing asymmetry tends, therefore, to occur in stressed marginal habitats. Genetic perturbations implying genomic stress include certain specific genes, directional selection, inbreeding, and chromosome balance alterations. It is for these reasons that transgenic organisms may show increased FA. As there is evidence that the effects of genomic and environmental stress are cumulative, organisms in a state of genomic stress may provide sensitive biological monitors of environmental stress.
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paper_title: Fluctuating asymmetry, metabolic rate and sexual selection in human males

paper_content:

Abstract Fluctuating asymmetry (FA), a measure of developmental stability, may be important in human sexual selection, that is in mate choice and male-male competition. It is shown that in males (but not in females) resting metabolic rate (RMR) is positively related to FA. This is explained in terms of the balanced energy equation of males. Sexual selection for large body size (resulting from male-male competition) and low FA (a consequence of mate choice) results in a stress on the provision of energy for growth and the maintenance of symmetry. Viewed in this way, sexual selection is similar to any other stress such as overcrowding and starvation. High-quality males are better able to withstand the stress of sexual selection than low-quality males. The former have “energy-thrifty genotypes” and are able to allocate more energy to growth and reducing FA than the latter.
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paper_title: Fluctuating asymmetry as an indicator of stress: Implications for conservation biology

paper_content:

Abstract Extinction can be attributed broadly to environmental or genetic stress. The ability to detect such stresses before they seriously affect a population can enhance the effectiveness of conservation programs. Recent studies have shown that within-individual morphological variability may provide a valuable early indicator of environmental and genetic stress.
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paper_title: Is symmetry a visual cue to attractiveness in the human female body

paper_content:

Small deviations from bilateral symmetry (a phenomenon called fluctuating asymmetry [FA]) are believed to arise due to an organism's inability to implement a developmental program when challenged by developmental stress. FA thus provides an index of an organism's exposure to adverse environmental effects and its ability to resist these effects. If one wishes to choose an individual with good health and fertility, FA could be used as an index of a potential partner's suitability. To explore whether this theory can be applied to human female bodies (excluding heads), we used a specially developed software package to create images with perfect symmetry. We then compared the relative attractiveness of the normal (asymmetric image) with the symmetric image. When male and female observers rated the images for attractiveness on a scale of 1 to 10, there was no significant difference in attractiveness between the symmetric and asymmetric images. However, in a two-alternative forced-choice experiment, the symmetric image was significantly more popular. The evidence suggests a role for symmetry in the perception of the attractiveness of the human female body.
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paper_title: Facial attractiveness signals different aspects of “quality” in women and men

paper_content:

We explored the relationships between facial attractiveness and several variables thought to be related to genotypic and phenotypic quality in humans (namely fluctuating asymmetry (FA), body mass index (BMI), health, age). To help resolve some controversy around previous studies, we used consistent measurement and statistical methods and relatively large samples of both female (n = 94) and male (n = 95) subjects (to be evaluated and measured), and female (n = 226) and male (n = 153) viewers (to rate attractiveness). We measured the asymmetry of 22 traits from three trait families (eight facial, nine body and five fingerprint traits) and constructed composite asymmetry indices of traits showing significant repeatability. Facial attractiveness was negatively related to an overall asymmetry index in both females and males, with almost identical slopes. Female facial attractiveness was best predicted by BMI and past health problems, whereas male facial attractiveness was best predicted by the socioeconomic status (SES) of their rearing environment. Composite FA indices accounted for a small ( < 4%) but usually significant percentage of the variation in facial attractiveness in both sexes, when factors related to asymmetry were controlled statistically. We conclude that, although facial attractiveness is negatively related to developmental instability (as measured by asymmetry), attractiveness also signals different aspects of ‘‘quality’’ in the two sexes, independent of FA. D 2001 Elsevier Science Inc. All rights reserved.
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paper_title: Human hips, breasts and buttocks: Is fat deceptive?

paper_content:

Abstract In humans, reproductive-age females, unlike other ages and classes of individuals, deposit fat preferentially on the breasts, hips, and buttocks. This suggests that such fat deposition is a deceptive sexual signal, mimicking other signals of high reproductive value and potential.
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paper_title: Evolutionary Theory and African American Self-Perception: Sex Differences in Body-Esteem Predictors of Self-Perceived Physical and Sexual Attractiveness, and Self-Esteem

paper_content:

Evolutionary biological theory has been shown to be relevant to an understanding of how individuals assess others' physical and sexual attractiveness. This research used the Body-Esteem Scale and multiple regression to determine if this theory is also relevant to an understanding of self-perceived physical and sexual attractiveness and self-esteem for a sample of 91 African Americans. The hypotheses that regression models of physical and sexual attractiveness would differ within and across sex groups and that models of self-esteem would differ across sex groups in accordance with evolutionary theory were supported. Attributes of the body related to fecundity and successful mothering characteristics predicted for women and attributes of the body related to strength and dominance predicted for men. In addition, attributes of the body dealing with sexual maturity were stronger predictors of sexual attractiveness for women. This research indicates that evolutionary biological theory can provide relevant insig...
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paper_title: Female health, attractiveness, and desirability for relationships: Role of breast asymmetry and waist-to-hip ratio

paper_content:

Abstract Fluctuating asymmetry (FA) of ordinarily bilaterally symmetrical traits in humans has been proposed to indicate developmental anomaly. Recent research has shown that individuals with minimal FA are judged to be attractive, and preferred as sexual partners (Thornhill and Gangestad 1993). Waist-to-hip ratios (WHR) have been also shown to reflect health and reproductive capability of woman and those with low WHRs are judged more attractive and healthy (Singh 1993a,b). The present study examines the relative roles of WHR and FA in female breasts in judgments of female attractiveness, health, and desirability for short-term and long-term relationships. Male college students were asked to judge attractiveness of female figures that differed in WHR (high and low) and breast symmetry (none, low, or high). In the first test, paired comparison method was used in which each figure was paired one at a time with all other figures. In the second test, subjects examined all figures simultaneously, estimated their age, and rated each figure for attractiveness, feminine looks, health, overall degree of body symmetry, and willingness to engage in short- and long-term relationship. Results from both tests show that figures with low WHRs were judged to be more attractive than figures with high WHRs, regardless of their degree of breast asymmetry. The figure with low WHR and symmetrical breasts was judged to be most attractive and youngest of all other figures. It appears that men use both WHR and breast asymmetry in judging attractiveness and being willing to develop romantic relationships. It is proposed that WHR and breast asymmetry may signal different aspects of overall female mate quality.
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paper_title: Evolutionary Theory and Self-perception: Sex Differences in Body Esteem Predictors of Self-perceived Physical and Sexual Attractiveness and Self-Esteem

paper_content:

Responses to the body esteem scale (Franzoi & Shields, 1984) and multiple regression were used to determine if evolutionary biological theory is relevant to an understanding of self-perceived physical and sexual attractiveness and selfesteem and to determine if physical and sexual attractiveness are the same construct. It was hypothesized that regression models of physical and sexual attractiveness would differ within and across sex groups and that models of self-esteem would differ across sex groups in accordance with evolutionary theory. These hypotheses were supported. Attributes of the body related to fecundity and successful mothering characteristics predicted for women and attributes of the body related to strength and dominance predicted for men. In addition, attributes of the body dealing with sexual maturity were stronger predictors of sexual attractiveness. Physical and sexual attractiveness are not the same constructs. This research indicates that evolutionary bological theory can provide relev...
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paper_title: FLUCTUATING ASYMMETRY AND SEXUAL SELECTION

paper_content:

Fluctuating asymmetry occurs when an individual is unable to undergo identical development on both sides of a bilaterally symmetrical trait. Fluctuating asymmetry measures the sensitivity of development to a wide array of genetic and environmental stresses. We propose that fluctuating asymmetry is used in many signalling contexts for assessment of an individual's ability to cope with its environment. We hypothesize that fluctuating asymmetry is used in sexual selection, both in fighting and mate choice, and in competition for access to resources. Evidence is reviewed showing that the patterns of fluctuating asymmetry in secondary sexual characters differ from those seen in other morphological traits. Secondary sexual characters show much higher levels of fluctuating asymmetry. Also, there is often a negative relationship between fluctuating asymmetry and the absolute size of ornaments, whereas the relationship is typically U-shaped in other morphological traits. The common negative relationship between fluctuating asymmetry and ornament size suggests that many ornaments reliably reflect individual quality.
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paper_title: Ratings of voice attractiveness predict sexual behavior and body configuration

paper_content:

Abstract We investigated the relationship between ratings of voice attractiveness and sexually dimorphic differences in shoulder-to-hip ratios (SHR) and waist-to-hip ratios (WHR), as well as different features of sexual behavior. Opposite-sex voice attractiveness ratings were positively correlated with SHR in males and negatively correlated with WHR in females. For both sexes, ratings of opposite-sex voice attractiveness also predicted reported age of first sexual intercourse, number of sexual partners, number of extra-pair copulation (EPC) partners, and number of partners that they had intercourse with that were involved in another relationship (i.e., were themselves chosen as an EPC partner). Coupled with previous findings showing a relationship between voice attractiveness and bilateral symmetry, these results provide additional evidence that the sound of a person's voice may serve as an important multidimensional fitness indicator.
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paper_title: Vocal and visual attractiveness are related in women

paper_content:

Abstract We investigated the relation between visual and vocal attractiveness in women as judged by men. We recorded 34 women speaking four vowels and measured the peak frequency, the first five harmonic frequencies, the first five formant frequencies and formant dispersion. The women were also photographed (head shot), several body measures were taken and their ages were recorded. The voices were played to male judges who were asked to assess the women's age and vocal attractiveness from the recording. The men were then asked to assess the attractiveness of the photographs. Men were in strong agreement on which was an attractive voice and face; and women with attractive faces had attractive voices. Higher-frequency voices were assessed as being more attractive and as belonging to younger women (the lowest frequency produced is a good indicator of age in women in general). Larger women had lower voices and were judged as having less attractive faces and voices. Taller women had narrower formant dispersion as predicted. The results imply that different measures of attractiveness are in agreement and signal similar qualities, such as female age, body size and possibly hormonal profile. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.
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paper_title: The voice and face of woman: one ornament that signals quality?

paper_content:

Abstract The attractiveness of women's faces, voices, bodies, and odors appear to be interrelated, suggesting that they reflect a common trait such as femininity. We invoked novel approaches to test the interrelationships between female vocal and facial attractiveness and femininity. In Study 1, we examined the relationship between facial-metric femininity and voice pitch in two female populations. In both populations, facial-metric femininity correlated positively with pitch of voice. In Study 2, we constructed facial averages from two populations of women with low- and high-pitched voices and determined men's preferences for resulting prototypes. Men preferred averaged faces of women from both populations with higher pitched voices to those with lower pitched voices. In Study 3, we tested whether the findings from Study 2 also extended to the natural faces that made up the prototypes. Indeed, men and women preferred real faces of women with high-pitched voices to those with low-pitched voices. Because multiple cues to femininity are related, and feminine women may have greater reproductive fitness than do relatively masculine women, male preferences for multiple cues to femininity are potentially adaptive.
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paper_title: Mating context and menstrual phase affect women's preferences for male voice pitch

paper_content:

Abstract Fundamental frequency ( F 0 ) is the vocal acoustic parameter closest to what we perceive as pitch. Men speak at a lower F 0 than do women, even controlling for body size. Although the developmental and anatomical reasons for this sex difference are known, the evolutionary reasons are not. By examining fertility-related variation in women's preferences for men's voices, the present study tests the hypothesis that female choice for good genes influenced the evolution of male voice pitch (VP). Unlike previous correlational studies that did not consider the effects of menstrual phase and mating context on women's preferences for male VP, the present study includes these variables and utilizes experimental pitch (P) manipulations. Results indicate that low VP is preferred mainly in short-term mating contexts rather than in long-term, committed ones, and this mating context effect is greatest when women are in the fertile phase of their ovulatory cycles. Moreover, lower male F 0 correlated with higher self-reported mating success. These findings are consistent with the hypothesis that an association between low male VP and heritable fitness led to the evolution of the observed patterns in women's P preferences and men's mating success and that these patterns influenced the evolution of low VP in men. However, alternative explanations are considered.
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paper_title: Androgen Stimulation and Laryngeal Development

paper_content:

Androgen-induced changes in laryngeal growth patterns were studied using a sheep animal model. Forty-eight lambs were divided into eight treatment groups. Lambs in seven of the groups were castrated at birth, while lambs in the eighth group served as an intact (noncastrated) control. Six groups were then treated with varying doses of testosterone and dihydrotestosterone, while the seventh served as a castrated, nontreated control. All animals were killed and gross dissections of the larynges were performed. Thirty-four linear and angular measurements were obtained from each larynx. The mean superior thyroid horn separation showed the most dramatic androgen-induced effect (p = 0.023). Laryngeal anterior-posterior diameter, superior thyroid horn height, posterior thyroid cartilage width, thyroid cartilage angle, and vocal process to arytenoid base distances all demonstrated positive dose-response relationships. Hypoandrogenic levels appeared to have an inhibitory effect upon laryngeal growth when compared to castrated controls.
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paper_title: Men's voices and women's choices

paper_content:

I investigated the relationship between male human vocal characteristics and female judgements about the speaker. Thirty-four males were recorded uttering five vowels and measures were taken, from power spectrums, of the first five harmonic frequencies, overall peak frequency and formant frequencies (emphasized, resonance, frequencies within the vowel). Male body measures were also taken (age, weight, height, and hip and shoulder width) and the men were asked whether they had chest hair. The recordings were then played to female judges, who were asked to rate the males' attractiveness, age, weight and height, and to estimate the muscularity of the speaker and whether he had a hairy chest. Men with voices in which there were closely spaced, low-frequency harmonics were judged as being more attractive, older and heavier, more likely to have a hairy chest and of a more muscular body type. There was no relationship between any vocal and body characteristic. The judges' estimates were incorrect except for weight. They showed extremely strong agreement on all judgements. The results imply that there could be sexual selection through female choice for male vocal characteristics, deeper voices being preferred. However, the function of the preference is unclear given that the estimates were generally incorrect.
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paper_title: Menstrual cycle variation in women's preferences for the scent of symmetrical men

paper_content:

Evidence suggests that female sexual preferences change across the menstrual cycle. Women’s extra-pair copulations tend to occur in their most fertile period, whereas their intra-pair copulations tend to be more evenly spread out across the cycle.This pattern is consistent with women preferentially seeking men who evidence phenotypic markers of genetic bene¢ts just before and during ovulation.This study examined whether women’s olfactory preferences for men’s scent would tend to favour the scent of more symmetrical men, most notably during the women’s fertile period. College women sniied and rated the attractiveness of the scent of 41T-shirts worn over a period of two nights by diierent men. Results indicated that normally cycling (non-pill using) women near the peak fertility of their cycle tendedto prefer the scent of shirts worn by symmetrical men. Normally ovulating women at low fertility within their cycle, and women using a contraceptive pill, showed no signi¢cant preference for either symmetrical or asymmetrical men’s scent. A separate analysis revealed that, within the set of normally cycling women, individual women’s preference for symmetry correlated with their probability of conception, given the actuarial value associated with the day of the cycle they reported at the time they smelled the shirts. Potential sexual selection processes and proximate mechanisms accounting for these ¢ndings are discussed.
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paper_title: The Scent of Symmetry: A Human Sex Pheromone that Signals Fitness?

paper_content:

Abstract A previous study by the authors showed that the body scent of men who have greater body bilateral symmetry is rated as more attractive by normally ovulating (non-pill-using) women during the period of highest fertility based on day within the menstrual cycle. Women in low-fertility phases of the cycle and women using hormone-based contraceptives do not show this pattern. The current study replicated these findings with a larger sample and statistically controlled for men's hygiene and other factors that were not controlled in the first study. The current study also examined women's scent attractiveness to men and found no evidence that men prefer the scent of symmetric women. We propose that the scent of symmetry is an honest signal of phenotypic and genetic quality in the human male, and chemical candidates are discussed. In both sexes, facial attractiveness (as judged from photos) appears to predict body scent attractiveness to the opposite sex. Women's preference for the scent associated with men's facial attractiveness is greatest when their fertility is highest across the menstrual cycle. The results overall suggest that women have an evolved preference for sires with good genes.
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paper_title: Differential use of sensory information in sexual behavior as a function of gender

paper_content:

Olfactory information is critical to mammalian sexual behavior. Based on parental investment theory the relative importance of olfaction compared with vision, touch, and hearing should be different for human males and females. In particular, because of its link to immunological profile and offspring viability, odor should be a more important determinant of sexual choice and arousal for females than for males. To test this hypothesis a questionnaire was developed and administered to 332 adults (166 males, 166 females). Subjects used a 1–7 scale to indicate how much they agreed with a series of statements concerning the importance of olfactory, visual, auditory, and tactile information for their sexual responsivity. The data reveal that males rated visual and olfactory information as being equally important for selecting a lover, while females considered olfactory information to be the single most important variable in mate choice. Additionally, when considering sexual activity, females singled out body odor from all other sensory experiences as most able to negatively affect desire, while males regarded odors as much more neutral stimuli for sexual arousal. The present results support recent findings in mice and humans concerning the relation of female preferences in body odor and major histocompatibility complex (MHC) compatibility and can be explained by an evolutionary analysis of sex differences in reproductive strategies. This work represents the first direct examination of the role of different forms of sensory information in human sexual behavior.
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paper_title: Human body odour, symmetry and attractiveness

paper_content:

Several studies have found body and facial symmetry as well as attractiveness to be human mate choice criteria. These characteristics are presumed to signal developmental stability. Human body odour has been shown to influence female mate choice depending on the immune system, but the question of whether smell could signal general mate quality, as do other cues, was not addressed in previous studies. We compared ratings of body odour, attractiveness, and measurements of facial and body asymmetry of 16 male and 19 female subjects. Subjects wore a T-shirt for three consecutive nights under controlled conditions. Opposite-sex raters judged the odour of the T-shirts and another group evaluated portraits of the subjects for attractiveness. We measured seven bilateral traits of the subject's body to assess body asymmetry. Facial asymmetry was examined by distance measurements of portrait photographs. The results showed a significant positive correlation between facial attractiveness and sexiness of body odour for female subjects. We found positive relationships between body odour and attractiveness and negative ones between smell and body asymmetry for males only if female odour raters were in the most fertile phase of their menstrual cycle. The outcomes are discussed in the light of different male and female reproductive strategies.
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paper_title: Major histocompatibility complex genes, symmetry, and body scent attractiveness in men and women

paper_content:

Previous research indicates that the scent of developmental stability (low fluctuating asymmetry, FA) is attractive to women who are fertile (at high-conception risk points in their menstrual cycles), but not to other women or men. Prior research also indicates that the scent of dissimilarity in major histocompatibility complex (MHC) genes may play a role in human mate choice. We studied the scent attractiveness to the opposite sex of t-shirts worn for 2 nights' sleep. Our results indicate that the two olfactory systems are independent. We repeated previous results from studies of the scent of symmetry. We repeated previous results from MHC research in part; men, but not women, showed a preference for t-shirts with the scent of MHC dissimilarity. Women's scent ratings of t-shirts were uncorrelated with the wearer's MHC dissimilarity and allele frequency, but positively correlated with the wearer's MHC heterozygosity. Fertile women did not exhibit any MHC trait preferences. Women's preference for the scent of men who were heterozygous for MHC alleles may be stronger in women who are at infertile cycle points. Men preferred the scent of common MHC alleles, which may function to avoid mates with rare alleles that exhibit gestational drive. Men also preferred the scent of women at fertile cycle points. The scent of facially attractive women, but not men, was preferred. Neither FA nor facial attractiveness in either sex correlated with MHC dissimilarity to others, MHC heterozygosity, or MHC allelic rarity. Copyright 2003.
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paper_title: Olfactory information processing during the course of the menstrual cycle

paper_content:

Abstract In the present study we examined whether olfactory information processing depends on the phase of the menstrual cycle. Five female subjects were investigated during three phases (follicular, ovulatory, luteal) of their menstrual cycle. In each session chemosensory (olfactory) event-related potentials (CSERP) were recorded and olfactory thresholds and the hedonic tone of the test stimulus (citral) were determined. Threshold values were correlated with the salivary cortisol level. The results show that olfactory perception changes during the menstrual cycle. After the first stimulus presentations in a recording session, odors were perceived as more complex or novel during the ovulatory period (enhanced amplitude of P3-1). With continued stimulation, odor processing became faster (reduced latency of N1, P2 and P3-2) around ovulation and slower during the follicular phase. Moreover, odors were described more differentially during the ovulatory period. Olfactory sensitivity was correlated positively with the peripheral cortisol level.
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paper_title: Evolutionary Theory Led to Evidence for a Male Sex Pheromone That Signals Symmetry

paper_content:

In several studies, we asked the question, "Do women find the scent of symmetrical men more pleasant and sexier, particularly on the days of their menstrual cycles when they could potentially conceive an offspring?" (Gangestad & Thomhill, 1998; Thomhill & Gangestad, 1 999b; Thornhill et al., in press). As this question appears to concern a small, rather circumscribed piece of human psychology, why did we ask it? Why was it interesting? And what impact, if any, has it had on addressing larger questions of significance? In short, the question arose rather straightforwardly from modem evolutionary theory. We asked the question not simply because we were interested in women's scent preferences in particular (though we certainly are) but rather we asked it precisely because an answer to the question, embedded within a much larger corpus of theory and evidence, potentially speaks to very broad issues concerning not only human sexuality and male-female relations but also wide-ranging topics such as the development and expression of a wide variety of physical and behavioral traits, same-sex interactions, maternal-fetal interactions, and conflicts within the human genome. We would like to think that the research and what it has led to already illustrate the generative power of well-established, broad theory. Theory is often thought of as generative in a deductive fashion, allowing researchers to derive predictions about phenomena of interest. It certainly is that. However, theory is generative through induction as well, and particularly when it is extremely broad, touching on phenomena not only of core interest but perhaps even outside of one's own particular science. New facts that must be assimilated into a theoretical network may have perturbing effects throughout its reach and may dictate altered understandings of phenomena within its purview.
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paper_title: Gender differences in beliefs about the causes of male and female sexual desire

paper_content:

Little is known about the beliefs men and women have about the causes of sexual desire, despite the interpersonal and individual significance of those beliefs. Participants in this study received a definition of sexual desire and answered a set of free-response questions exploring their beliefs about the causal antecedents of male and female sexual desire. The results indicated that more women than men view female (and male) sexual desire as caused by external factors. In addition, both men and women believe that male and female sexual desire have different causes: intraindividual and erotic environmental factors are believed to cause male sexual desire, but interpersonal and romantic environmental factors are believed to cause female sexual desire. Although both men and women view physical attractiveness and overall personality as sexually desirable male and female characteristics, women, but not men, view femininity as a sexually desirable female characteristic, and men, but not women, view social and financial power or status as a sexually desirable male attribute.
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paper_title: Fluctuating asymmetry and psychometric intelligence

paper_content:

Little is known about the genetic nature of human psychometric intelligence (IQ), but it is widely assumed that IQ's heritability is at loci for intelligence per se. We present evidence consistent with a hypothesis that interindividual IQ differences are partly due to heritable vulnerabilities to environmental sources of developmental stress, an indirect genetic mechanism for the heritability of IQ. Using fluctuating asymmetry (FA) of the body (the asymmetry resulting from errors in the development of normally symmetrical bilateral traits under stressful conditions), we estimated the relative developmental instability of 112 undergraduates and administered to them Cattell's culture fair intelligence test (CFIT). A subsequent replication on 128 students was performed. In both samples, FA correlated negatively and significantly with CFIT scores. We propose two non–mutually exclusive physiological explanations for this correlation. First, external body FA may correlate negatively with the developmental integrity of the brain. Second, individual energy budget allocations and/or low metabolic efficiency in high–FA individuals may lower IQ scores. We review the data on IQ in light of our findings and conclude that improving developmental environmental quality may increase average IQ in future generations.
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paper_title: Human intelligence, fluctuating asymmetry and the peacock’s tail: General intelligence (g) as an honest signal of fitness

paper_content:

Assuming that general intelligence (g) is an honest signal of fitness, we expected g to be related to developmental quality as indexed by Fluctuating Asymmetry (i.e. non-pathological variation in the size of right and left body features). In a population sample of 44 men and 37 women, we assessed the relationship between Fluctuating Asymmetry (FA) and g, and, as a control, to the Big Five personality dimensions for which no theoretical relationship with FA was expected. We found a relation between g and FA in men and women, but only a marginally significant relation with Openness in women only. We conclude that about 20% of the variance in g is explained by FA, and discuss the implications for the evolution of g and human mate choice.
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paper_title: Facial asymmetry as an indicator of psychological, emotional, and physiological distress

paper_content:

Fluctuating asymmetry (FA) is deviation from bilateral symmetry in morphological traits with asymmetry values that are normally distributed with a mean of 0. FA is produced by genetic or environmental perturbations of developmental design and may play a role in human sexual selection. K. Grammer and R. Thornhill (1994) found that facial FA negatively covaries with observer ratings of attractivenes s, dominance, sexiness, and health. Using self-reports, observer ratings, daily diary reports, and psychophysiological measures, the authors assessed the relationship between facial FA and health in 2 samples of undergraduate s (N = 101). Results partially replicate and extend those of K. Grammer and R. Thornhill (1994) and suggest that facial FA may signal psychological, emotional, and physiological distress. Discussion integrates the authors' findings with previous research on FA and suggests future research needed to clarify the role of FA in human sexual selection.
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paper_title: The evolutionary psychology of extrapair sex: The role of fluctuating asymmetry

paper_content:

Abstract This study explored evolutionary hypotheses concerning extrapair sex (or EPCs: extrapair copulations). Based on recent notions about sexual selection, we predicted that (a) men's number of EPCs would correlate negatively with their fluctuating asymmetry, a measure of the extent to which developmental design is imprecisely expressed, and (b) men's number of times having been an EPC partner of a woman would negatively correlate with their fluctuating asymmetry. In a sample of college heterosexual couples, both hypotheses were supported. In addition, men's physical attractiveness independently predicted how often they had been an EPC partner. Women's anxious attachment style positively covaried with their number of EPC partners, whereas their avoidant attachment style negatively covaried with their number of EPC partners.
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paper_title: Facial Asymmetry and Attractiveness Judgment in Developmental Perspective

paper_content:

This study examined the role of facial symmetry in the judgment of physical attractiveness. Four experiments investigated people's preference for either somewhat asymmetrical portraits or their symmetrical chimeric composites when presented simultaneously. Experiment 1 found a higher selection rate for symmetrical faces with neutral expression for portraits of old people, and Experiment 2 indicated this may be because symmetry serves as cue for youth in old age. In Experiments 3 and 4 participants examined portraits with emotional expressions. Experiment 3 found a higher selection rate for asymmetrical faces, and Experiment 4 indicated this may be because observers perceived them as more genuine and natural. This study suggests that the low degree of facial asymmetry found in normal people does not affect attractiveness ratings (except for old age), probably because observers are not tuned to perceive it.
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paper_title: Fluctuating asymmetry and human male life-history traits in rural Belize

paper_content:

Fluctuating asymmetry (FA), used as a measure of phenotypic quality, has proven to be a useful predictor of human life–history variation, but nothing is known about its effects in humans living in higher fecundity and mortality conditions, typical before industrialization and the demographic transition. In this research, I analyse data on male life histories for a relatively isolated population in rural Belize. Some of the 56 subjects practise subsistence–level slash–and–burn farming, and others are involved in the cash economy. Fecundity levels are quite high in this population, with men over the age of 40 averaging more than eight children. Low FA successfully predicted lower morbidity and more offspring fathered, and was marginally associated with a lower age at first reproduction and more lifetime sex partners. These results indicate that FA may be important in predicting human performance in fecundity and morbidity in pre–demographic transition conditions.
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paper_title: Fluctuating asymmetry and intelligence

paper_content:

Abstract The general factor of mental ability ( g ) may reflect general biological fitness. If so, g -loaded measures such as Raven's progressive matrices should be related to morphological measures of fitness such as fluctuating asymmetry (FA: left–right asymmetry of a set of typically left–right symmetrical body traits such as finger lengths). This prediction of a negative correlation between FA and IQ was confirmed in two independent samples, with correlations of − 0.41 and − 0.29, respectively. Head size also predicted Raven's scores but this relationship appeared to be mediated by FA. It is concluded that g along with correlated variables such as head size are in large part a reflection of a more general fitness factor influencing the growth and maintenance of all bodily systems, with brain function being an especially sensitive indicator of this fitness factor.
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paper_title: FACIAL ATTRACTIVENESS AND PHYSICAL HEALTH

paper_content:

Abstract Previous research has documented that more facially attractive people are perceived by others to be physically healthier. Using self-reports, observer ratings, daily diary methodology, and psychophysiological assessments, this study provides limited empirical evidence that more facially attractive people ( N = 100) may be physically healthier than unattractive people. Discussion suggests the value of an evolutionary psychological perspective for understanding the relationship between facial attractiveness and physical health.
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paper_title: Human female orgasm and mate fluctuating asymmetry

paper_content:

Abstract Human, Homo sapiens , female orgasm is not necessary for conception; hence it seems reasonable to hypothesize that orgasm is an adaptation for manipulating the outcome of sperm competition resulting from facultative polyandry. If heritable differences in male viability existed in the evolutionary past, selection could have favoured female adaptations (e.g. orgasm) that biased sperm competition in favour of males possessing heritable fitness indicators. Accumulating evidence suggests that low fluctuating asymmetry is a sexually selected male feature in a variety of species, including humans, possibly because it is a marker of genetic quality. Based on these notions, the proportion of a woman's copulations associated with orgasm is predicted to be associated with her partner's fluctuating asymmetry. A questionnaire study of 86 sexually active heterosexual couples supported this prediction. Women with partners possessing low fluctuating asymmetry and their partners reported significantly more copulatory female orgasms that were reported by women with partners possessing high fluctuating asymmetry and their partners, even with many potential confounding variables controlled. The findings are used to examine hypotheses for female orgasm other than selective sperm retention.
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paper_title: Human sperm competition: ejaculate manipulation by females and a function for the female orgasm

paper_content:

. Behavioural ecologists view monogamy as a subtle mixture of conflict and cooperation between the sexes. In part, conflict and cooperation is cryptic, taking place within the female's reproductive tract. In this paper the cryptic interaction for humans was analysed using data from both a nationwide survey and counts of sperm inseminated into, and ejected by, females. On average, 35% of sperm were ejected by the female within 30 min of insemination. The occurrence and timing of female orgasm in relation to copulation and male ejaculation influenced the number of sperm retained at both the current and next copulation. Orgasms that climaxed at any time between 1 min before the male ejaculated up to 45 min after led to a high level of sperm retention. Lack of climax or a climax more than 1 min before the male ejaculated led to a low level of sperm retention. Sperm from one copulation appeared to hinder the retention of sperm at the next copulation for up to 8 days. The efficiency of the block declined with time after copulation but was fixed at its current level by an inter-copulatory orgasm which thus reduced sperm retention at the next copulation. Inter-copulatory orgasms are either spontaneous (= nocturnal) or induced by self-masturbation or stimulation by a partner. It is argued that orgasms generate a blow-suck mechanism that takes the contents of the upper vagina into the cervix. These contents include sperm and seminal fluid if present; acidic vaginal fluids if not. Inter-copulatory orgasms will therefore lower the pH of the cervical mucus and either kill or reduce the mobility of any sperm that attempt to penetrate from reservoirs in the cervical crypts. Intercopulatory orgasms may also serve an antibiotic function. Copulatory and inter-copulatory orgasms endow females with considerable flexibility in their manipulation of inseminates. The data suggest that, in purely monandrous situations, females reduced the number of sperm retained, perhaps as a strategy to enhance conception. During periods of infidelity, however, females changed their orgasm pattern. The changes would have been cryptic to the male partners and would numerically have favoured the sperm from the extra-pair male, presumably raising his chances of success in sperm competition with the female's partner.
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paper_title: Facial attractiveness, symmetry and cues of good genes

paper_content:

Cues of phenotypic condition should be among those used by women in their choice of mates. One marker of better phenotypic condition is thought to be symmetrical bilateral body and facial features. However, it is not clear whether women use symmetry as the primary cue in assessing the phenotypic quality of potential mates or whether symmetry is correlated with other facial markers affecting physical attractiveness. Using photographs of men's faces, for which facial symmetry had been measured, we found a relationship between women's attractiveness ratings of these faces and symmetry, but the subjects could not rate facial symmetry accurately. Moreover, the relationship between facial attractiveness and symmetry was still observed, even when symmetry cues were removed by presenting only the left or right half of faces. These results suggest that attractive features other than symmetry can be used to assess phenotypic condition. We identified one such cue, facial masculinity (cheek-bone prominence and a relatively longer lower face), which was related to both symmetry and full- and half-face attractiveness.
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paper_title: Developmental Stability, Ejaculate Size, and Sperm Quality in Men

paper_content:

Abstract There is accumulating evidence that women prefer symmetric men. This preference would be adaptive if symmetry was correlated with a fitness trait such as fertility. We show that, in a sample of 53 men from an infertility clinic, a measure of overall absolute fluctuating asymmetry (FA) in digits 2 to 5 was negatively related to sperm number per ejaculate, sperm speed, and sperm migration, and overall relative FA was negatively related to sperm number and sperm speed. Subjects who had few or no sperm in their ejaculates (azoospermics) tended to have high FA, particularly when obstructive azoospermia was the likely diagnosis. Controlling for weight, height, and age left sperm number, sperm speed, and sperm migration significantly related to both absolute and relative FA. The association between low digit FA and large ejaculates and high sperm quality may arise because (1) generalized developmental stability of the body is related to fertility or (2) Hox genes control differentiation of digits and the urinogenital system in vertebrates, and FA of the former is closely linked to developmental stability of the latter.
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paper_title: Human Fluctuating Asymmetry and Sexual Behavior

paper_content:

This report presents evidence that sexual selection may favor developmental stability (i e, the absence of fluctuating asymmetry) in humans Subtle, heritable asymmetries in seven nonfacial human body traits correlated negatively with number of self-reported, lifetime sex partners and correlated positively with self-reported age at first copulation in a college student sample These relationships remained statistically significant when age, marital status, body height, ethnicity, physical anomalies associated with early prenatal development, and physical attractiveness were statistically controlled The strength of the relationships did not differ significantly as a function of sex It is unlikely that the relationships are generated by false self-reporting of sexual experience
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paper_title: Bilateral symmetry and sexual selection: a meta-analysis.

paper_content:

A considerable body of primary research has accumulated over the last 10 yr testing the relationship between developmental instability in the form of fluctuating asymmetry and performance of individuals in mating success itself or sexual attractiveness. This research comprises 146 samples from 65 studies of 42 species of four major taxa. We present the results of a meta-analysis of these studies, which demonstrates that there is indeed an overall significant, moderate negative relationship: for studies, the overall mean Pearson's r or effect size = -.42, P <.0005; for species, the overall mean r = -.34, .01 < P < .025. Based on calculated fail-safe numbers, the effect-size estimates are highly robust against any publication or reporting bias that may exist. There is considerable evidence that the magnitude of the negative correlation between fluctuating asymmetry and success related to sexual selection is greater for males than for females, when a secondary sexual trait rather than an ordinary trait is studied, with experimentation compared with observation, and for traits not involved with mobility compared with traits affecting mobility. There is also limited evidence that higher taxa may differ in effect size and that intensity of sexual selection negatively correlates with effect size.
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paper_title: Study of genetic variance in the fluctuating asymmetry of anthropometrical traits

paper_content:

SummaryWe have studied the fluctuating asymmetry (FA) of 8 bilateral morphometric traits in two-parent families, comprising 216 families with one newborn baby, and 60 families with two children (age range 5–18 years). Heritability was assessed by: (1) multiple regression analyses of the children's measurements on the mother's and father's measurements; (2) midparent-child regressions; and (3) sibling correlations. The extent of genetic determination of individual FA measurements was generally low, albeit statistically significant in some cases. However, even these correlations were inconsistent between samples and relatives. However, the mean FA values for all 8 studied traits showed positive and significant correlation between parents and children in two samples and in total. Additive genetic variance, calculated from multiple regression analyses and midparent-child correlations, was estimated to be between 0·25–0·30. Three multiple regressions (two for the separate group and one for the total sample) yi...
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paper_title: Human Fluctuating Asymmetry and Sexual Behavior

paper_content:

This report presents evidence that sexual selection may favor developmental stability (i e, the absence of fluctuating asymmetry) in humans Subtle, heritable asymmetries in seven nonfacial human body traits correlated negatively with number of self-reported, lifetime sex partners and correlated positively with self-reported age at first copulation in a college student sample These relationships remained statistically significant when age, marital status, body height, ethnicity, physical anomalies associated with early prenatal development, and physical attractiveness were statistically controlled The strength of the relationships did not differ significantly as a function of sex It is unlikely that the relationships are generated by false self-reporting of sexual experience
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paper_title: The evolutionary psychology of extrapair sex: The role of fluctuating asymmetry

paper_content:

Abstract This study explored evolutionary hypotheses concerning extrapair sex (or EPCs: extrapair copulations). Based on recent notions about sexual selection, we predicted that (a) men's number of EPCs would correlate negatively with their fluctuating asymmetry, a measure of the extent to which developmental design is imprecisely expressed, and (b) men's number of times having been an EPC partner of a woman would negatively correlate with their fluctuating asymmetry. In a sample of college heterosexual couples, both hypotheses were supported. In addition, men's physical attractiveness independently predicted how often they had been an EPC partner. Women's anxious attachment style positively covaried with their number of EPC partners, whereas their avoidant attachment style negatively covaried with their number of EPC partners.
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paper_title: Facial Asymmetry and Attractiveness Judgment in Developmental Perspective

paper_content:

This study examined the role of facial symmetry in the judgment of physical attractiveness. Four experiments investigated people's preference for either somewhat asymmetrical portraits or their symmetrical chimeric composites when presented simultaneously. Experiment 1 found a higher selection rate for symmetrical faces with neutral expression for portraits of old people, and Experiment 2 indicated this may be because symmetry serves as cue for youth in old age. In Experiments 3 and 4 participants examined portraits with emotional expressions. Experiment 3 found a higher selection rate for asymmetrical faces, and Experiment 4 indicated this may be because observers perceived them as more genuine and natural. This study suggests that the low degree of facial asymmetry found in normal people does not affect attractiveness ratings (except for old age), probably because observers are not tuned to perceive it.
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paper_title: The evolution of monogamy and concealed ovulation in humans

paper_content:

Abstract Homo sapiens is unique among primates in that it is the only group-living species in which monogamy is the major mating system and the only species in which females do not reveal their ovulation by estrus. These unique traits can be explained in terms of natural selective and cultural selective theory applied at the level of the individual. The relative amount of parental investment by the sexes is an important correlate with the type of mating systems found in animal species. In human history the evolution of increased hunting abilities, bipedality, relatively altricial young and the concomitant dependency on the male for food by the female are viewed as the factors allowing and favoring increased male parental investment. The same scenario can explain the evolution of extensive female parental care in humans. Monogamy is the result of the male's investment being increased to approximate equality with that of the female and the male's attempt to insure his paternity. The incipient hunting activities of Australopithecus and small cranium would indicate polygyny at this stage of hominid evolution. The increase in hunting activities and brain size of Homo erectus may have favored monogamy. Polygyny may have reappeared to some extent with the evolution of Homo sapiens sapiens 40,000 B.P., but perhaps not until 15,000–11,000 B.P. did disparity in resources controlled by males allow some males to exceed the polygyny threshold. The loss of estrus in the female is regarded not as a precondition to pair-bonding, but as a means for increasing the likelihood of successful cuckoldry of the male after monogamy has been established. The human social setting of monogamous pairs in close proximity greatly reduces the costs of infidelity.
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paper_title: Extramarital sex: A review of the research literature

paper_content:

Abstract Research literature in the field of extramarital sex (EMS) is reviewed. Initially, definitional problems which reveal the need for increased rigor in specifying the sexual behavior under consideration, the dyad or group outside of which the behavior occurs, and the consensual or non‐consensual nature of the behavior are discussed. Twelve surveys of EMS are examined and the limitations of incidence rate figures discussed. Empirical studies have attempted to identify key variables which discriminate between EMS and non‐EMS samples. The findings of this research are summarized according to four variable categories: social background characteristics, characteristics of the marriage, personal readiness characteristics, and sex and gender differences. Characteristics of the marriage and personal readiness characteristics are found to be of prime importance in understanding EMS, although sex and gender differences frequently qualify major empirical relationships. The attitude continuum of extramarital s...
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paper_title: From vigilance to violence: Tactics of mate retention in American undergraduates

paper_content:

Although the attraction and selection of mates are central to human reproduction, the retention of acquired mates is often necessary to actualize the promise of reproductive effort. Three empirical studies used act frequency methods to identify, assess the reported performance frequencies of, and evaluate the perceived effectiveness of 19 tactics and 104 acts of human mate guarding and retention. In Study 1 (N = 105), a hierarchical taxonomy of tactics was developed from a pool of nominated acts. We then assessed the reported performance frequencies of 19 retention tactics and 104 acts and tested three hypotheses derived from evolutionary models in an undergraduate sample (N = 102). Study 2 (N = 46) provided an independent test of these hypotheses by assessing the perceived effectiveness of each tactic. Discussion draws implications for sexual poaching, susceptibility to pair-bond defection, and the power of act frequency methods for preserving the proximate specificity and systemic complexity inherent in human mating processes.
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paper_title: Menstrual cycle shifts in women's self-perception and motivation: A daily report method

paper_content:

Few systematic studies have examined differences in women’s behaviour across the entire menstrual cycle. Previous research indicates that women’s sexual motivation and mating behaviour increases near ovulation, as well as sexual desire and selection of provocative clothing. We investigated whether self-perception varies across the menstrual cycle, i.e., whether women consider themselves to be more attractive near ovulation. As a hypothesized by-product of increased desire and a reflection of short-term sexual strategy selection, we tested changes in clothing style, use of cosmetics, and purchasing behaviour across the menstrual cycle. We adopted the daily report method of estimated fertility (Haselton & Gangestad, 2006; Schwarz & Hassebrauck, 2008) over 35 days with 25 College age women who were not taking any kind of hormonal contraceptives. Women reported feeling more attractive and desirable, increased sexual interest and appearance related styling at the days near ovulation (i.e., when conception likelihood was high) than on the other days of the menstrual cycle. However, no significant differences between high and low fertile phases were found for purchasing behaviour. We discuss our results with reference to the evolutionary psychology of female fertility and mating related behaviour.
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paper_title: Second to fourth digit ratio in elite musicians : Evidence for musical ability as an honest signal of male fitness

paper_content:

Abstract Prenatal testosterone may facilitate musical ability. The ratio of the length of the second and fourth digit (2D:4D) is probably determined in utero and is negatively related to adult testosterone concentrations and sperm numbers per ejaculate. Therefore, 2D:4D may be a marker for prenatal testosterone levels. We tested the association between 2D:4D and musical ability by measuring the ratio in 70 musicians (54 men and 16 women) recruited from a British symphony orchestra. The men had significantly lower 2D:4D ratios (indicating high testosterone) than controls ( n = 86). The mean 2D:4D of women did not differ significantly from controls ( n = 78). Rankings of musical ability within the orchestra were associated with male 2D:4D (high rank=low 2D:4D). Differences in 2D:4D ratio were not found among instrument groups, suggesting that 2D:4D was not related to mechanical advantages in playing particular intruments. Concert audiences showed evidence of a female-biased sex ratio in seats close to the orchestra. This preliminary study supports the thesis that music is a sexually selected trait in men that indicates fertilizing capacity and perhaps good genes. However, the association between low 2D:4D ratio and orchestra membership and high status within the orchestra may result from testosterone-mediated competitive ability. Further tests of the association between 2D:4D and musical ability per se are necessary.
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paper_title: The ratio of 2nd to 4th digit length: a predictor of sperm numbers and concentrations of testosterone, luteinizing hormone and oestrogen.

paper_content:

The differentiation of the urinogenital system and the appendicular skeleton in vertebrates is under the control of Hox genes. The common control of digit and gonad differentiation raises the possibility that patterns of digit formation may relate to spermatogenesis and hormonal concentrations. This work was concerned with the ratio between the length of the 2nd and 4th digit (2D:4D) in humans. We showed that (i) 2D:4D in right and left hands has a sexually dimorphic pattern; in males mean 2D:4D = 0.98, i.e. the 4th digit tended to be longer than the 2nd and in females mean 2D:4D = 1.00, i.e. the 2nd and 4th digits tended to be of equal length. The dimorphism is present from at least age 2 years and 2D:4D is probably established in utero; (ii) high 2D:4D ratio in right hands was associated with germ cell failure in men (P = 0.04); (iii) sperm number was negatively related to 2D:4D in the right hand (P = 0.004); (iv) in men testosterone concentrations were negatively related to right hand 2D:4D and in women and men LH (right hand), oestrogen (right and left hands) and prolactin (right hand) concentrations were positively correlated with 2D:4D ratio and (v) 2D:4D ratio in right hands remained positively related to luteinizing hormone and oestrogen after controlling for sex, age, height and weight.
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paper_title: Hormonal response to competition in human males

paper_content:

Changes in testosterone (T) and cortisol (C) were evaluated in males competing in a non-athletic laboratory reaction time task. Subjects were randomly assigned to “win” or “lose” by adjusting feedback regarding their task performance. Further, subjects were randomly assigned to either a Close Contest condition (where one person barely “defeated” his opponent), or a Decisive condition (in which the victory was clear). Throughout competition, samples of saliva were taken and assayed later for T and C. Post-competition mood and attributions were also measured. Winners had higher overall T levels than losers, with no significant difference between Close Contest or Decisive Victory conditions. In contrast, C levels did not differ between winners and losers nor did Condition (Close or Decisive) have any effect. Mood was depressed in Decisive losers compared to all other groups. The results indicate that the perception of winning or losing, regardless of actual performance or merit on the task, differentially influenced T (but not C) levels, and that such hormonal changes are not simply general arousal effects but are related to mood and status change.
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paper_title: Derogation of Competitors

paper_content:

Verbal signals are sometimes used to manipulate the impressions that people form about oneself and others. For the goal of self-enhancement, one can manipulate impressions either by elevating oneself or by derogating others. Five hypotheses about derogation of same-sex competitors were generated from an evolutionary model of human-mate competition. These hypotheses focused on sex differences in the importance that humans attach to external resources, rank, achievements, physical prowess, reproductive value and fidelity. Four studies were conducted to test these hypotheses. In a preliminary study (N = 80), subjects nominated intrasexual derogation tactics they had previously observed. Study 1 (N = 120) examined estimates of the likelihood that men and women would perform each tactic. Study 2 (N = 101) identified the perceived effectiveness of each derogation tactic for men and women. Study 3 (N = 100) used act reports based on self-recording and observer-recording to identify the likelihood of specific per...
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paper_title: Digit ratio (2D:4D) and physical fitness in males and females: Evidence for effects of prenatal androgens on sexually selected traits

paper_content:

It has been suggested that male achievement in sports and athletics is correlated with a putative measure of prenatal testosterone the 2nd to 4th digit ratio (2D:4D). It is not known whether this association also extends to females, or whether the association results from an effect of testosterone on behavior (such as exercise frequency) or on physical fitness. Here, we report for the first time data from two studies which consider associations between 2D:4D and physical fitness in females in addition to males: Study I—in a sample of teenage boys (n = 114) and girls (n = 175), their ‘physical education grade’ was negatively associated with 2D:4D of the right hand (boys), and right and left hand (girls), and Study II—among a sample of young men (n = 102) and women (n = 77), a composite measure of physical fitness was negatively related to right hand 2D:4D in men and left hand 2D:4D in women. We conclude that 2D:4D is negatively related to physical fitness in both men and women. In Study II, there was evidence that the relationship between physical fitness and 2D:4D in men was mediated through an association with exercise frequency. Thus, 2D:4D in males may be a negative correlate of frequent exercise which then relates to achievement in sports and athletics.
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paper_title: Second to fourth digit ratio and facial asymmetry

paper_content:

Several studies have reported a positive association between degree of facial symmetry and attractiveness ratings, although the actual causes of the development of facial asymmetries remains to be confirmed. The current study hypothesizes that early hormone levels may play a crucial role in the development of facial asymmetries. Recent evidence suggests that the relative length of the second to fourth finger (2D:4D) is negatively related to prenatal testosterone and positively related to prenatal estrogen and may thus serve as a window to the prenatal hormonal environment. We measured 2D:4D in a sample of male and female college students and analysed their faces for horizontal asymmetries. 2D:4D was significantly negatively related to facial asymmetry in males, whereas in females facial asymmetry was significantly positively related to 2D:4D. We suggest that digit ratio may thus be considered as a pointer to an individual's developmental instability and stress through its association with prenatal sexual steroids.
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paper_title: Facial attractiveness, symmetry and cues of good genes

paper_content:

Cues of phenotypic condition should be among those used by women in their choice of mates. One marker of better phenotypic condition is thought to be symmetrical bilateral body and facial features. However, it is not clear whether women use symmetry as the primary cue in assessing the phenotypic quality of potential mates or whether symmetry is correlated with other facial markers affecting physical attractiveness. Using photographs of men's faces, for which facial symmetry had been measured, we found a relationship between women's attractiveness ratings of these faces and symmetry, but the subjects could not rate facial symmetry accurately. Moreover, the relationship between facial attractiveness and symmetry was still observed, even when symmetry cues were removed by presenting only the left or right half of faces. These results suggest that attractive features other than symmetry can be used to assess phenotypic condition. We identified one such cue, facial masculinity (cheek-bone prominence and a relatively longer lower face), which was related to both symmetry and full- and half-face attractiveness.
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paper_title: Symmetry and Performance in Middle Distance Runners

paper_content:

Deviations from perfect symmetry in paired traits such as ear size and nostril width may indicate developmental instability and/or short-term fluctuations in hormones. In both cases symmetry is thought to be optimal and to indicate high pheno-typic quality. The purpose of this work was to determine the relationship between symmetry and performance in middle-distance runners. Fifty male subjects participated in this study. Deviations from perfect bilateral symmetry were measured in seven traits; ear size, nostril width, 2nd to 5th digit length and wrist width. After measurements were made the subjects were ranked for athletic ability and they reported their best 800 metre and 1500 metre times. Symmetric subjects had higher rankings for athletic ability (nostrils, p < 0.001 and ears, p < 0.001), lower best 800 metre times (nostrils, p < 0.05 and ears, p < 0.01) and lower best 1500 metre times (3rd digit, p < 0.01 and ears, p < 0.05) than asymmetric subjects. This conclusion remained essentially the same after Bonferroni adjustment for multiple tests and when experience and age were controlled for in multiple regression tests. We conclude that symmetry in traits such as nostrils and ears indicates good running ability. It may therefore be useful in predicting the future potential of young athletes.
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paper_title: Evolutionary Theory and African American Self-Perception: Sex Differences in Body-Esteem Predictors of Self-Perceived Physical and Sexual Attractiveness, and Self-Esteem

paper_content:

Evolutionary biological theory has been shown to be relevant to an understanding of how individuals assess others' physical and sexual attractiveness. This research used the Body-Esteem Scale and multiple regression to determine if this theory is also relevant to an understanding of self-perceived physical and sexual attractiveness and self-esteem for a sample of 91 African Americans. The hypotheses that regression models of physical and sexual attractiveness would differ within and across sex groups and that models of self-esteem would differ across sex groups in accordance with evolutionary theory were supported. Attributes of the body related to fecundity and successful mothering characteristics predicted for women and attributes of the body related to strength and dominance predicted for men. In addition, attributes of the body dealing with sexual maturity were stronger predictors of sexual attractiveness for women. This research indicates that evolutionary biological theory can provide relevant insig...
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paper_title: Second to fourth digit ratios and individual differences in women's self-perceived attractiveness, self-esteem, and body-esteem

paper_content:

Abstract This research examined the relationship between women’s digit ratios (2D:4D) and self-perceived attractiveness, self-esteem and body-esteem. Sixty women rated their physical and sexual attractiveness, self-esteem, and body-esteem. Digit ratios (2D:4D) were determined from tracings of their hands. Based on prior research, it was hypothesized that women with high 2D:4D ratios would find themselves more physically attractive and possibly exhibit higher self-esteem and body-esteem. The results obtained supported the hypothesis for attractiveness. Women with high 2D:4D ratios rated their physical attractiveness higher. These results are discussed in terms of evolutionary theory and prior research.
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paper_title: The ratio of 2nd to 4th digit length and male homosexuality

paper_content:

Abstract Sexual orientation may be influenced by prenatal levels of testosterone and oestrogen. There is evidence that the ratio of the length of 2nd and 4th digits (2D:4D) is negatively related to prenatal testosterone and positively to oestrogen. We report that (a) 2D:4D was lower in a sample of 88 homosexual men than in 88 sex- and age-matched controls recruited without regard to sexual orientation, (b) within the homosexual sample, there was a significant positive relationship between mean 2D:4D ratio and exclusive homosexuality, (c) overall, there was a decrease in 2D:4D from controls to homosexual men to bisexual men and (d) fraternal birth order, a positive predictor of male homosexuality, was not associated with 2D:4D in a sample of 240 Caucasian men recruited without regard to sexual orientation and 45 homosexual men. Further work is needed to confirm the relationships between 2D:4D and sexual orientation. However, these and other recent data tend to support an association between male homosexuality and high fetal testosterone. Very high testosterone levels may be associated with a sexual preference for both men and women.
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paper_title: Second to fourth digit ratio and male ability in sport: implications for sexual selection in humans

paper_content:

Abstract Fetal and adult testosterone may be important in establishing and maintaining sex-dependent abilities associated with male physical competitiveness. There is evidence that the ratio of the length of the 2nd and 4th digits (2D:4D) is a negative correlate of prenatal and adult testosterone. We use ability in sports, and particularly ability in football, as a proxy for male physical competitiveness. Compared to males with high 2D:4D ratio, men with low ratio reported higher attainment in a range of sports and had higher mental rotation scores (a measure of visual–spatial ability). Professional football players had lower 2D:4D ratios than controls. Football players in 1st team squads had lower 2D:4D than reserves or youth team players. Men who had represented their country had lower ratios than those who had not, and there was a significant (one-tailed) negative association between 2D:4D and number of international appearances after the effect of country was removed. We suggest that prenatal and adult testosterone promotes the development and maintenance of traits which are useful in sports and athletics disciplines and in male:male fighting.
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paper_title: Length of index and ring fingers differentially influence sexual attractiveness of men’s and women’s hands

paper_content:

Humans show intra- and intersexual variation in second (2D) relative to fourth (4D) finger length, men having smaller 2D:4D ratio, possibly because of differential exposure to sex hormones during fetal life. The relations between 2D:4D and phenotypic traits including fitness components reported by several studies may originate from the organizational effects that sex hormones have on diverse organs and their concomitant effect on 2D:4D. Evolutionary theory posits that sexual preferences are adaptations whereby choosy individuals obtain direct or genetic indirect benefits by choosing a particular mate. Since sex hormones influence both fitness and 2D:4D, hand sexual attractiveness should depend on 2D:4D, a hypothesis tested only in one correlational study so far. We first presented hand computer images to undergraduates and found that opposite-sex hands with long 2D and 4D were considered more sexually attractive. When we experimentally manipulated hand images by increasing or decreasing 2D and/or 4D length, women preferred opposite-sex hands that had been masculinized by elongating 4D, whereas men avoided masculinized opposite-sex right hands with shortened 2D. Hence, consensus exists about which hands are attractive among different opposite-sex judges. Finger length may signal desirable sex hormone-dependent traits or genetic quality of potential mates. Psychological mechanisms mediating hand attractiveness judgments may thus reflect adaptations functioning to provide direct or indirect benefits to choosy individuals. Because the genetic mechanisms that link digit development to sex hormones may be mediated by Hox genes which are conserved in vertebrates, present results have broad implications for sexual selection studies also in nonhuman taxa.
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paper_title: Ovulatory shifts in human female ornamentation: Near ovulation, women dress to impress

paper_content:

Humans differ from many other primates in the apparent absence of obvious advertisements of fertility within the ovulatory cycle. However, recent studies demonstrate increases in women's sexual motivation near ovulation, raising the question of whether human ovulation could be marked by observable changes in overt behavior. Using a sample of 30 partnered women photographed at high and low fertility cycle phases, we show that readily-observable behaviors – self-grooming and ornamentation through attractive choice of dress – increase during the fertile phase of the ovulatory cycle. At above-chance levels, 42 judges selected photographs of women in their fertile (59.5%) rather than luteal phase (40.5%) as “trying to look more attractive.” Moreover, the closer women were to ovulation when photographed in the fertile window, the more frequently their fertile photograph was chosen. Although an emerging literature indicates a variety of changes in women across the cycle, the ornamentation effect is striking in both its magnitude and its status as an overt behavioral difference that can be easily observed by others. It may help explain the previously documented finding that men's mate retention efforts increase as their partners approach ovulation.
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paper_title: Evolutionary Theory and Self-perception: Sex Differences in Body Esteem Predictors of Self-perceived Physical and Sexual Attractiveness and Self-Esteem

paper_content:

Responses to the body esteem scale (Franzoi & Shields, 1984) and multiple regression were used to determine if evolutionary biological theory is relevant to an understanding of self-perceived physical and sexual attractiveness and selfesteem and to determine if physical and sexual attractiveness are the same construct. It was hypothesized that regression models of physical and sexual attractiveness would differ within and across sex groups and that models of self-esteem would differ across sex groups in accordance with evolutionary theory. These hypotheses were supported. Attributes of the body related to fecundity and successful mothering characteristics predicted for women and attributes of the body related to strength and dominance predicted for men. In addition, attributes of the body dealing with sexual maturity were stronger predictors of sexual attractiveness. Physical and sexual attractiveness are not the same constructs. This research indicates that evolutionary bological theory can provide relev...
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paper_title: Digit Ratio: A Pointer to Fertility, Behavior, and Health

paper_content:

The main message of this book is simple and John Manning does an excellent job of delivering it clearly. The ratio of second and fourth (finger) digit lengths (2D:4D) appears to be affected by foetal testosterone exposure, may be fixed before birth, and so may be a reliable indicator of early prenatal conditions and subsequent health factors.
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paper_title: Facial symmetry and the big-five personality factors

paper_content:

The present study investigated possible associations between facial symmetry and actual personality as assessed by the 'big-five' personality factors: neuroticism (N), extraversion (E), openness (O), agreeableness (A), and conscientiousness (C). Digital photographs were taken of male and female faces, volunteers also completed the NEO-FFI personality inventory. Facial images were analysed for horizontal symmetry by means of digital image processing. Following previous reports we predicted that facial symmetry should be negatively related to neuroticism but positively related to extraversion, openness, agreeableness, and conscientiousness. In general, our data on actual personality confirmed previous reports on perceptions of personality for neuroticism and extraversion. Neuroticism was found to be negatively but not significantly related to facial symmetry whereas extraversion was positively associated. In contrast to previous data, we found significant negative associations between facial symmetry and openness and agreeableness. Conscientiousness was non-significantly related to facial symmetry. The strongest associations with facial symmetry were found for extraversion and openness. Our results suggest that behavioural perceptions of an individual may reflect an individual's actual personality, and facial symmetry is a correlate of personality. However, because of some inconsistencies between this and previous studies we suggest that (1) the associations between facial symmetry and personality traits require further investigation, and (2) future studies should urge for methodological consistency to make results comparable.
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paper_title: The effect of facial symmetry on perceptions of personality and attractiveness

paper_content:

Abstract The present study examined the effect of facial symmetry on perceptions of personality and physical attractiveness. Digital photographs of female targets were manipulated into symmetrical and asymmetrical versions and then presented to undergraduate raters along with the “normal” photograph, which was not manipulated for symmetry. Based on the hypothesis that facial symmetry is used as an indicator of health, we predicted that the asymmetrical version of the faces would be perceived as more Neurotic, but less Extraverted, Open, Agreeable, Conscientious, and attractive, relative to the other versions. As predicted, the asymmetrical faces were rated as significantly more Neurotic, less Agreeable and less Conscientious than the normal versions. However, facial symmetry did not affect ratings of Openness and Extraversion, nor did it affect ratings of attractiveness.
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paper_title: Inferences of competence from faces predict election outcomes.

paper_content:

We show that inferences of competence based solely on facial appearance predicted the outcomes of U.S. congressional elections better than chance (e.g., 68.8% of the Senate races in 2004) and also were linearly related to the margin of victory. These inferences were specific to competence and occurred within a 1-second exposure to the faces of the candidates. The findings suggest that rapid, unreflective trait inferences can contribute to voting choices, which are widely assumed to be based primarily on rational and deliberative considerations.
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paper_title: Personality and Mate Preferences: Five Factors In Mate Selection and Marital Satisfaction

paper_content:

ABSTRACT Although personality characteristics figure prominently in what people want in a mate, little is known about precisely which personality characteristics are most important, whether men and women differ in their personality preferences, whether individual women or men differ in what they want, and whether individuals actually get what they want. To explore these issues, two parallel studies were conducted, one using a sample of dating couples (N= 118) and one using a sample of married couples (N= 216). The five-factor model, operationalized in adjectival form, was used to assess personality characteristics via three data sources—self-report, partner report, and independent interviewer reports. Participants evaluated on a parallel 40-item instrument their preferences for the ideal personality characteristics of their mates. Results were consistent across both studies. Women expressed a greater preference than men for a wide array of socially desirable personality traits. Individuals differed in which characteristics they desired, preferring mates who were similar to themselves and actually obtaining mates who embodied what they desired. Finally, the personality characteristics of one's partner significantly predicted marital and sexual dissatisfaction, most notably when the partner was lower on Agreeableness, Emotional Stability, and Intellect-Openness than desired.
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paper_title: Consensus in interpersonal perception: acquaintance and the big five.

paper_content:

Consensus refers to the extent to which judges agree in their ratings of a common target. Consensus has been an important area of research in social and personality psychology. In this article, generalizability theory is used to develop a percentage of total variance measure of consensus. This measure is used to review the level of consensus across 32 studies by considering the role of acquaintance level and trait dimension. The review indicates that consensus correlations ranged from zero to about .3, with higher levels of consensus for ratings of Extraversion. The studies do not provide evidence that consensus increases with increasing acquaintance, a counterintuitive result that can be accounted for by a theoretical model (D.A. Kenny, 1991, in press). Problems in the interpretation of longitudinal research are reviewed.
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paper_title: Facing faces: Studies on the cognitive aspects of physiognomy.

paper_content:

Physiognomy, the art of reading personality traits from faces, dates back to ancient Greece, and is still very popular. The present studies examine several aspects and consequences of the process of reading traits from faces. Using faces with neutral expressions, it is demonstrated that personality information conveyed in faces changes the interpretation of verbal information. Moreover, it is shown that physiognomic information has a consistent effect on decisions, and creates overconfidence in judgments. It is argued, however, that the process of "reading from faces" is just one side of the coin, the other side of which is "reading into faces." Consistent with the latter, information about personality changes the perception of facial features and, accordingly, the perceived similarity between faces. The implications of both processes and questions regarding their automaticity are discussed. There are some people whose faces bear the stamp of such artless vulgarity and baseness of character, such an animal limitation of intelligence, that one wonders how they can appear in public with such a countenance, instead of wearing a mask. (Schopenhauer, 1942, p. 63)
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paper_title: Facial symmetry is positively associated with self-reported extraversion

paper_content:

Abstract Fink et al. (2005) reported significant associations between facial symmetry and scores on some of the “big five” personality dimensions derived from self-report data. In particular, they identified a positive association between facial symmetry and extraversion, but negative associations between facial symmetry and both agreeableness and openness. Fink et al. (2005) used a measure of facial symmetry based on analysis of the central region of each face. In the present study we attempted to replicate these findings with a much larger sample (N = 294) and using a landmark-based measure of facial symmetry that includes peripheral regions of the face. In both sexes, we found a significant positive association between self-reported extraversion and facial symmetry but were unable to replicate any of the other previously reported associations. Nevertheless, the positive association between symmetry and extraversion provides further support for the idea that facial appearance could predict personality and therefore makes it possible for some personality attributions to be “data driven”, i.e. driven by properties of the target.
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paper_title: Male facial attractiveness: evidence for hormone-mediated adaptive design

paper_content:

Abstract Experimenters examining male facial attractiveness have concluded that the attractive male face is (1) an average male face, (2) a masculinized male face, or (3) a feminized male face. Others have proposed that symmetry, hormone markers, and the menstrual phase of the observer are important variables that influence male attractiveness. This study was designed to resolve these issues by examining the facial preferences of 42 female volunteers at two different phases of their menstrual cycle. Preferences were measured using a 40-s QuickTime movie (1200 frames) that was designed to systematically modify a facial image from an extreme male to an extreme female configuration. The results indicate that females exhibit (1) a preference for a male face on the masculine side of average, (2) a shift toward a more masculine male face preference during the high-risk phase of their menstrual cycle, and (3) no shift in other facial preferences. An examination of individual differences revealed that women who scored low on a "masculinity" test (1) showed a larger menstrual shift, (2) had lower self-esteem, and (3) differed in their choice of male faces for dominance and short-term mates. The results are interpreted as support for a hormonal theory of facial attractiveness whereby perceived beauty depends on an interaction between displayed hormone markers and the hormonal state of the viewer.
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paper_title: Facial asymmetry as an indicator of psychological, emotional, and physiological distress

paper_content:

Fluctuating asymmetry (FA) is deviation from bilateral symmetry in morphological traits with asymmetry values that are normally distributed with a mean of 0. FA is produced by genetic or environmental perturbations of developmental design and may play a role in human sexual selection. K. Grammer and R. Thornhill (1994) found that facial FA negatively covaries with observer ratings of attractivenes s, dominance, sexiness, and health. Using self-reports, observer ratings, daily diary reports, and psychophysiological measures, the authors assessed the relationship between facial FA and health in 2 samples of undergraduate s (N = 101). Results partially replicate and extend those of K. Grammer and R. Thornhill (1994) and suggest that facial FA may signal psychological, emotional, and physiological distress. Discussion integrates the authors' findings with previous research on FA and suggests future research needed to clarify the role of FA in human sexual selection.
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paper_title: Facial attractiveness, symmetry and cues of good genes

paper_content:

Cues of phenotypic condition should be among those used by women in their choice of mates. One marker of better phenotypic condition is thought to be symmetrical bilateral body and facial features. However, it is not clear whether women use symmetry as the primary cue in assessing the phenotypic quality of potential mates or whether symmetry is correlated with other facial markers affecting physical attractiveness. Using photographs of men's faces, for which facial symmetry had been measured, we found a relationship between women's attractiveness ratings of these faces and symmetry, but the subjects could not rate facial symmetry accurately. Moreover, the relationship between facial attractiveness and symmetry was still observed, even when symmetry cues were removed by presenting only the left or right half of faces. These results suggest that attractive features other than symmetry can be used to assess phenotypic condition. We identified one such cue, facial masculinity (cheek-bone prominence and a relatively longer lower face), which was related to both symmetry and full- and half-face attractiveness.
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paper_title: Psychopathy and developmental instability

paper_content:

Abstract Psychopaths are manipulative, impulsive, and callous individuals with long histories of antisocial behavior. Two models have guided the study of psychopathy. One suggests that psychopathy is a psychopathology, i.e., the outcome of defective or perturbed development. A second suggests that psychopathy is a life-history strategy of social defection and aggression that was reproductively viable in the environment of evolutionary adaptedness (EEA). These two models make different predictions with regard to the presence of signs of perturbations or instability in the development of psychopaths. In Study 1, we obtained data on prenatal, perinatal, and neonatal signs of developmental perturbations from the clinical files of 643 nonpsychopathic and 157 psychopathic male offenders. In Study 2, we measured fluctuating asymmetry (FA, a concurrent sign of past developmental perturbations) in 15 psychopathic male offenders, 25 nonpsychopathic male offenders, and 31 male nonoffenders. Psychopathic offenders scored lower than nonpsychopathic offenders on obstetrical problems and FA; both psychopathic and nonpsychopathic offenders scored higher than nonoffenders on FA. The five offenders from Study 2 meeting the most stringent criteria for psychopathy were similar to nonoffenders with regard to FA and had the lowest asymmetry scores among offenders. These results provide no support for psychopathological models of psychopathy and partial support for life-history strategy models.
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paper_title: Evolutionary Theory and African American Self-Perception: Sex Differences in Body-Esteem Predictors of Self-Perceived Physical and Sexual Attractiveness, and Self-Esteem

paper_content:

Evolutionary biological theory has been shown to be relevant to an understanding of how individuals assess others' physical and sexual attractiveness. This research used the Body-Esteem Scale and multiple regression to determine if this theory is also relevant to an understanding of self-perceived physical and sexual attractiveness and self-esteem for a sample of 91 African Americans. The hypotheses that regression models of physical and sexual attractiveness would differ within and across sex groups and that models of self-esteem would differ across sex groups in accordance with evolutionary theory were supported. Attributes of the body related to fecundity and successful mothering characteristics predicted for women and attributes of the body related to strength and dominance predicted for men. In addition, attributes of the body dealing with sexual maturity were stronger predictors of sexual attractiveness for women. This research indicates that evolutionary biological theory can provide relevant insig...
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paper_title: Dermatoglyphic fluctuating asymmetry and atypical handedness in schizophrenia

paper_content:

Atypical handedness and dermatoglyphic abnormalities are hypothesized to reflect a neurodevelopmental disturbance in schizophrenia. Developmental instability, indexed by dermatoglyphic fluctuating asymmetry (FA), reflects the degree to which an individual's ontogenetic program is maintained and provides a useful framework in which to consider atypical handedness in schizophrenia. Thirty patients diagnosed with schizophrenia were compared with 37 matched healthy controls on levels of dermatoglyphic FA, a demonstration task determining hand preference and a test of relative hand skill. Multivariate analyses established that patients demonstrated greater FA and more atypical hand skill compared with controls. In patients, but not in controls, there was a strong positive association between a measure of FA and a measure of atypical hand skill, suggesting that these markers of neurodevelopmental disturbance are related in schizophrenia. On a measure of hand preference, patients were more likely than controls to be classified as mixed handed than either right or left handed. Results from the present study support the conjecture of greater developmental instability in schizophrenia affecting neurodevelopmental processes, including those conferring manual dominance.
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paper_title: Invisible Men: Evolutionary Theory and Attractiveness and Personality Evaluations of 10 African American Male Facial Shapes

paper_content:

The entire gamut of facial shapes has not been included in prior research investigating the perception of African American men’s facial attractiveness. The 10 facial shapes identified for African American men (elliptic, oval, reversed oval, round, rectangular, quadratic, rhombic, trapezium, inverted trapezium, and pentagonal) were examined in this research. Based on evolutionary theory and prior research, the reversed oval, rectangular, trapezium, and inverted trapezium faces were hypothesized to be rated as most attractive, most dominant, most mature, most masculine, strongest, and most socially competent. Smaller, round, or oval faces were hypothesized to be perceived as warmest. The results obtained were consistent with these hypotheses. These findings are discussed in terms of evolutionary psychological adaptations and prior research.
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paper_title: Evolutionary Theory and Self-perception: Sex Differences in Body Esteem Predictors of Self-perceived Physical and Sexual Attractiveness and Self-Esteem

paper_content:

Responses to the body esteem scale (Franzoi & Shields, 1984) and multiple regression were used to determine if evolutionary biological theory is relevant to an understanding of self-perceived physical and sexual attractiveness and selfesteem and to determine if physical and sexual attractiveness are the same construct. It was hypothesized that regression models of physical and sexual attractiveness would differ within and across sex groups and that models of self-esteem would differ across sex groups in accordance with evolutionary theory. These hypotheses were supported. Attributes of the body related to fecundity and successful mothering characteristics predicted for women and attributes of the body related to strength and dominance predicted for men. In addition, attributes of the body dealing with sexual maturity were stronger predictors of sexual attractiveness. Physical and sexual attractiveness are not the same constructs. This research indicates that evolutionary bological theory can provide relev...
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paper_title: The Scent of Symmetry: A Human Sex Pheromone that Signals Fitness?

paper_content:

Abstract A previous study by the authors showed that the body scent of men who have greater body bilateral symmetry is rated as more attractive by normally ovulating (non-pill-using) women during the period of highest fertility based on day within the menstrual cycle. Women in low-fertility phases of the cycle and women using hormone-based contraceptives do not show this pattern. The current study replicated these findings with a larger sample and statistically controlled for men's hygiene and other factors that were not controlled in the first study. The current study also examined women's scent attractiveness to men and found no evidence that men prefer the scent of symmetric women. We propose that the scent of symmetry is an honest signal of phenotypic and genetic quality in the human male, and chemical candidates are discussed. In both sexes, facial attractiveness (as judged from photos) appears to predict body scent attractiveness to the opposite sex. Women's preference for the scent associated with men's facial attractiveness is greatest when their fertility is highest across the menstrual cycle. The results overall suggest that women have an evolved preference for sires with good genes.
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paper_title: Facial attractiveness, symmetry and cues of good genes

paper_content:

Cues of phenotypic condition should be among those used by women in their choice of mates. One marker of better phenotypic condition is thought to be symmetrical bilateral body and facial features. However, it is not clear whether women use symmetry as the primary cue in assessing the phenotypic quality of potential mates or whether symmetry is correlated with other facial markers affecting physical attractiveness. Using photographs of men's faces, for which facial symmetry had been measured, we found a relationship between women's attractiveness ratings of these faces and symmetry, but the subjects could not rate facial symmetry accurately. Moreover, the relationship between facial attractiveness and symmetry was still observed, even when symmetry cues were removed by presenting only the left or right half of faces. These results suggest that attractive features other than symmetry can be used to assess phenotypic condition. We identified one such cue, facial masculinity (cheek-bone prominence and a relatively longer lower face), which was related to both symmetry and full- and half-face attractiveness.
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paper_title: Human body odour, symmetry and attractiveness

paper_content:

Several studies have found body and facial symmetry as well as attractiveness to be human mate choice criteria. These characteristics are presumed to signal developmental stability. Human body odour has been shown to influence female mate choice depending on the immune system, but the question of whether smell could signal general mate quality, as do other cues, was not addressed in previous studies. We compared ratings of body odour, attractiveness, and measurements of facial and body asymmetry of 16 male and 19 female subjects. Subjects wore a T-shirt for three consecutive nights under controlled conditions. Opposite-sex raters judged the odour of the T-shirts and another group evaluated portraits of the subjects for attractiveness. We measured seven bilateral traits of the subject's body to assess body asymmetry. Facial asymmetry was examined by distance measurements of portrait photographs. The results showed a significant positive correlation between facial attractiveness and sexiness of body odour for female subjects. We found positive relationships between body odour and attractiveness and negative ones between smell and body asymmetry for males only if female odour raters were in the most fertile phase of their menstrual cycle. The outcomes are discussed in the light of different male and female reproductive strategies.
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paper_title: Facial symmetry detection ability changes across the menstrual cycle

paper_content:

The effects of menstrual cycle phase and hormones on women's visual ability to detect symmetry and visual preference for symmetry were examined. Participants completed tests of symmetry detection and preference for male facial symmetry at two of three menstrual cycle phases (menses, periovulatory, and luteal). Women were better at detecting facial symmetry during the menses than luteal phase of their cycle. A trend indicated the opposite pattern for dot symmetry detection. Similarly, change in salivary progesterone levels across the cycle was negatively related to change in facial symmetry detection scores. However, there was no clear evidence of a greater preference for facial symmetry at any cycle phase, despite an overall preference for facial symmetry across phases. These findings suggest a menses phase advantage and a low progesterone advantage in women's ability to detect facial symmetry. The results are discussed in the context of hormonal, evolutionary mate selection, and functional neurocognitive theories.
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Title: The Relationships between Symmetry and Attractiveness and Mating Relevant Decisions and Behavior: A Review

Section 1: Introduction
Description 1: This section provides an overview of the evolutionary basis for physical and sexual attractiveness, highlighting various facial and bodily traits that signal reproductive fitness and health.

Section 2: Developmental Stability
Description 2: This section defines developmental stability and explains its relevance to mate selection and attractiveness, emphasizing the role of symmetry.

Section 3: Facial Symmetry and Facial Attractiveness
Description 3: This section reviews the research on how facial symmetry influences perceptions of facial attractiveness and its evolutionary significance.

Section 4: Body Symmetry and Attractiveness
Description 4: This section discusses the relationship between overall body symmetry, specific body parts, and attractiveness.

Section 5: Breast Symmetry
Description 5: This section explores the importance of breast symmetry in assessments of female attractiveness and reproductive potential.

Section 6: Vocal Quality
Description 6: This section examines how vocal quality, pitch, and symmetry are associated with attractiveness and developmental stability.

Section 7: Pheromones
Description 7: This section investigates the role of pheromones in attractiveness and their association with symmetry.

Section 8: Mate Protection
Description 8: This section discusses how symmetry influences perceptions of a male's ability to protect his mate and offspring.

Section 9: Human Female Orgasm
Description 9: This section details the relationship between male symmetry and female orgasmic response during copulation.

Section 10: Sperm Quality
Description 10: This section explains the connection between symmetry and sperm quality, linking developmental stability with reproductive success.

Section 11: Sexual Behavior
Description 11: This section discusses the impact of symmetry on sexual behavior, including lifetime number of sexual partners and age of first intercourse.

Section 12: Infidelity
Description 12: This section reviews how symmetry influences the likelihood of engaging in extrapair copulations (EPCs) and infidelity.

Section 13: Athletic and Talent Displays
Description 13: This section examines the connection between symmetry and abilities in athletics, music, and dancing as displays of genetic quality and attractiveness.

Section 14: Personality
Description 14: This section explores how symmetry is related to personality traits and how these traits influence mate selection.

Section 15: Emotional and Psychological Health
Description 15: This section discusses the link between symmetry, psychological health, and emotional stability, highlighting its importance in attractiveness.

Section 16: Conclusions
Description 16: This section summarizes the key findings on the relationship between symmetry and attractiveness, and suggests directions for future research.