title: Structure of the United States Army

text: Prior to 1903, members of the National Guard were considered state soldiers unless federalized by the President. Since the Militia Act of 1903, all National Guard soldiers have held dual status: as National Guardsmen under the authority of the governors of their states and as a reserve of the U.S. Army under the authority of the President.


title: Structure of the United States Army

text: Since the adoption of the total force policy, in the aftermath of the Vietnam War, reserve component soldiers have taken a more active role in U.S. military operations. Reserve and Guard units took part in the Gulf War, peacekeeping in Kosovo, and the 2003 invasion of Iraq.


title: Structure of the United States Army

text: Although the present-day Army exists as an all-volunteer force, augmented by Reserve and National Guard forces, measures exist for emergency expansion in the event of a catastrophic occurrence, such as a large scale attack against the U.S. or the outbreak of a major global war.


title: Structure of the United States Army

text: The final stage of Army mobilization, known as "activation of the unorganized militia" would effectively place all able-bodied males in the service of the U.S. Army.


title: Structure of the United States Army

text: During World War I, the "National Army" was organized to fight the conflict. It was demobilized at the end of World War I.


title: Structure of the United States Army

text: After World War I, former units were replaced by the Regular Army, the Organized Reserve Corps, and the State Militias. In the 1920s and 1930s, the "career" soldiers were known as the "Regular Army" with the "Enlisted Reserve Corps" and "Officer Reserve Corps" augmented to fill vacancies when needed.


title: Structure of the United States Army

text: In 1941, the "Army of the United States" was founded to fight World War II. The Regular Army, Army of the United States, the National Guard, and Officer/Enlisted Reserve Corps (ORC and ERC) existed simultaneously.


title: Structure of the United States Army

text: After World War II, the ORC and ERC were combined into the United States Army Reserve. The Army of the United States was re-established for the Korean War and Vietnam War and was demobilized upon the suspension of the Draft.


title: Structure of the United States Army

text: The United States Army is made up of three components: one active—the Regular Army; and two reserve components—the Army National Guard and the Army Reserve. Both reserve components are primarily composed of part-time soldiers who train once a month, known as Battle Assembly, Unit Training Assemblies (UTAs), or simply "drills", while typically conducting two to three weeks of annual training each year. Both the Regular Army and the Army Reserve are organized under Title 10 of the United States Code. The National Guard is organized under Title 32. While the Army National Guard is organized, trained, and equipped as a component of the U.S. Army, individual units are under the command of individual states' governors. However, units of the National Guard can be federalized by presidential order and against the governor's wishes.


title: Structure of the United States Army

text: The U.S. Army is led by a civilian Secretary of the Army, who reports to the secretary of defense, and serves as civilian oversight for the Chief of Staff of the United States Army (CSA). The CSA is assisted by the Vice Chief of Staff of the United States Army. The CSA is a member of the Joint Chiefs of Staff, a body composed of the service chiefs from each service who advise the President of the United States and secretary of defense on military matters under the guidance of the chairman and vice chairman of the Joint Chiefs of Staff.


title: Structure of the United States Army

text: The Inspector General of the Army (IG) maintains open channels of communication for extraordinary issues which might lie outside the purview of the chain of command; it lists points of contact for the 3 Army Commands (ACOMs), the 11 Army Service Component Commands (ASCCs), and 12 Direct Reporting Units (DRUs). IG teams might then be assigned to a case, if need be, to perform inspections, assessments, and investigations.


title: Structure of the United States Army

text: Army Commands (ACOMs) and Army Service Component Commands (ASCCs) serve different purposes. The ACOMs are: Forces Command, Futures Command, Materiel Command, and Training and Doctrine Command.


title: Structure of the United States Army

text: Some of the Army Service Component Commands (ASCCs) are components of the six geographical Unified Combatant Commands (CCMDs). Other ASCCs serve the functional CCMDs.


title: Structure of the United States Army

text: Army Cyber Command is a component of United States Cyber Command. The commander of Army Cyber used to serve as commander of Second Army. Up until 2017, Second Army was a direct reporting unit to the Army CIO/G-6, with the CIO reporting to the Secretary of the Army, while the G-6 reports to the Army Chief of Staff. A 2017 reorganization eliminated the need for Second Army's network operations coordinating function, and the headquarters was inactivated on 31 March 2017. Army Network Enterprise Technology Command formerly reporting directly to the CIO/G-6, was a component of Second Army. The numerical designation 9th Army Signal Command has now been removed from NETCOM.


title: Structure of the United States Army

text: In addition, the Army's Special Operations Command administers its Joint Operations units; Space and Missile Defense Command provides global satellite-related infrastructure, and missile defense for the combatant commands, and for the nation. Surface Deployment and Distribution Command provides transport.


title: Structure of the United States Army

text: Most U.S. Army units can be operationally divided into the following components from largest to smallest:


title: Structure of the United States Army

text: For 2020, the Army plans to convert one SBCT to a ABCT, and one IBCT to a SBCT, which would bring the totals to 11 ABCTs, 7 SBCTs, and 13 IBCTs.


title: Structure of the United States Army

text: Combat formations of the US Army at below brigade level include the United States Army Special Forces groups and several reserve separate battalions (100–442 Inf (USAR), 3-172 Inf (Mtn) (Vermont Army National Guard) etc.).


title: Structure of the United States Army

text: Personnel in the Army work in various branches, which is their area of training or expertise. Traditionally, the branches were divided into three groups combat arms, combat support, and combat service support. Currently, the Army classifies its branches as maneuver, fires, and effects; operations support; and force sustainment.


title: Structure of the United States Army

text: Basic branches - contain groupings of military occupational specialties (MOS) in various functional categories, groups, and areas of the army in which officers are commissioned or appointed (in the case of warrant officers) and indicate an officer's broad specialty area. (For example, Infantry, Signal Corps, and Adjutant General's Corps.) Generally, officers are assigned to sequential positions of increasing responsibility and authority within one of the three functional categories of the army branches (Maneuver, Fires and Effects; Operations Support; Force Sustainment) to develop their leadership and managerial skills to prepare them for higher levels of command. The branches themselves are administrative vice operational command structures that are primarily involved with training, doctrine, and manpower concerns. Each branch has a Branch Chief who is the Head of the Branch and usually serves as the respective branch school commandant or director.


title: Structure of the United States Army

text: Special branches - contain those groupings of military occupational specialties (MOS) of the army in which officers are commissioned or appointed after completing advanced training and education and/or receiving professional certification in one of the classic professions (i.e., theology, law, or medicine), or other associated health care areas (e.g., dentistry, veterinary medicine, pharmacy, registered nurse, physician's assistant). Officers of most special branches are restricted to command of units and activities of their respective department/branch only, regardless of rank or seniority. This means, for example, that Army Medical Department (AMEDD) branch officers may only command AMEDD units and activities. Likewise, Chaplains are essentially "officers without command" and are ineligible to command operational units and activities. They do, however, supervise junior ranking chaplains and enlisted chaplain's assistants. As an exception to this general rule, JAG Corps officers are eligible to command and may be assigned (with permission from the Judge Advocate General) to non-legal command positions, although ordinarily, like other Special branch officers, a JAG officer will only lead JAG Corps units and activities during their career.


title: Structure of the United States Army

text: Each branch of the army has a different branch insignia. Per US Army Pamphlet 600-3, dated 1 February 2010, the three functional categories and associated functional groups for the branches and associated functional areas are:


title: Structure of the United States Army

text: Ten companies of riflemen were authorized by a resolution of the Continental Congress on 14 June 1775. However, the oldest Regular Army infantry regiment, the 3rd Infantry Regiment, was constituted on 3 June 1784, as the First American Regiment.


title: Structure of the United States Army

text: Following the establishment of the U.S. Air Force as a separate service in 1947, the army began to develop further its own aviation assets (light planes and rotary wing aircraft) in support of ground operations. The Korean War gave this drive impetus, and the war in Vietnam saw its fruition, as army aviation units performed a variety of missions, including reconnaissance, transport, and fire support. After the war in Vietnam, the role of armed helicopters as tank destroyers received new emphasis. In recognition of the growing importance of aviation in army doctrine and operations, aviation became a separate branch on 12 April 1983.


title: Structure of the United States Army

text: The Continental Congress unanimously elected Henry Knox "Colonel of the Regiment of Artillery" on 17 November 1775. The regiment formally entered service on 1 January 1776.


title: Structure of the United States Army

text: The Air Defense Artillery branch descended from the Anti-Aircraft Artillery (part of the U.S. Army Coast Artillery Corps) into a separate branch on 20 June 1968.


title: Structure of the United States Army

text: Continental Congress authority for a "Chief Engineer for the Army" dates from 16 June 1775. A corps of engineers for the United States was authorized by the Congress on 11 March 1789. The Corps of Engineers as it is known today came into being on 16 March 1802, when the President was authorized to "organize and establish a Corps of Engineers ... that the said Corps ... shall be stationed at West Point in the State of New York and shall constitute a Military Academy." A Corps of Topographical Engineers, authorized on 4 July 1838, was merged with the Corps of Engineers in March 1863.


title: Structure of the United States Army

text: The Chemical Warfare Service was established on 28 June 1918, combining activities that until then had been dispersed among five separate agencies of government. It was made a permanent branch of the Regular Army by the National Defense Act of 1920. In 1945, it was re-designated the Chemical Corps.


title: Structure of the United States Army

text: A Provost Marshal General's Office and Corps of Military Police were established in 1941. Prior to that time, except during the Civil War and World War I, there was no regularly appointed Provost Marshal General or regularly constituted Military Police Corps, although a "Provost Marshal" can be found as early as January 1776, and a "Provost Corps" as early as 1778.


title: Structure of the United States Army

text: The first special forces unit in the Army was formed on 11 June 1952, when the 10th Special Forces Group was activated at Fort Bragg, North Carolina. A major expansion of special forces occurred during the 1960s, with a total of eighteen groups organized in the Regular Army, Army Reserve, and Army National Guard. As a result of renewed emphasis on special operations in the 1980s, the Special Forces Branch was established as a basic branch of the army effective 9 April 1987, by General Order No. 35, 19 June 1987. Special forces are part of U.S. special operations forces


title: Structure of the United States Army

text: The Civil Affairs/Military Government Branch in the Army Reserve Branch was established as a special branch on 17 August 1955. It was subsequently redesignated the Civil Affairs Branch on 2 October 1955, and it has continued its mission to provide guidance to commanders in a broad spectrum of activities ranging from host–guest relationships to the assumption of executive, legislative, and judicial processes in occupied or liberated areas. Became a basic branch effective 16 October 2006 per General Order 29, on 12 January 2007.


title: Structure of the United States Army

text: The Signal Corps was authorized as a separate branch of the army by act of Congress on 3 March 1863. However, the Signal Corps dates its existence from 21 June 1860, when Congress authorized the appointment of one signal officer in the army, and a War Department order carried the following assignment: "Signal Department – Assistant Surgeon Albert J. Myer to be Signal Officer, with the rank of Major, 27 June 1860, to fill an original vacancy."


title: Structure of the United States Army

text: Intelligence has been an essential element of army operations during war as well as during periods of peace. In the past, requirements were met by personnel from the Army Intelligence and Army Security Reserve branches, two-year obligated tour officers, one-tour levies on the various branches, and Regular Army officers in the specialization programs. To meet the army's increased requirement for national and tactical intelligence, an Intelligence and Security Branch was established effective 1 July 1962, by General Order No. 38, on 3 July 1962. On 1 July 1967, the branch was re-designated as Military Intelligence.


title: Structure of the United States Army

text: The Quartermaster Corps, originally designated the Quartermaster Department, was established on 16 June 1775. While numerous additions, deletions, and changes of function have occurred, its basic supply and service support functions have continued in existence.


title: Structure of the United States Army

text: The Ordnance Department was established by act of Congress on 14 May 1812. During the Revolutionary War, ordnance material was under supervision of the Board of War and Ordnance. Numerous shifts in duties and responsibilities have occurred in the Ordnance Corps since colonial times. It acquired its present designation in 1950. Ordnance soldiers and officers provide maintenance and ammunition support.


title: Structure of the United States Army

text: The history of the Transportation Corps starts with World War I. Prior to that time, transportation operations were chiefly the responsibility of the Quartermaster General. The Transportation Corps, essentially in its present form, was organized on 31 July 1942. The Transportation Corps is headquartered at Fort Lee, Virginia.


title: Structure of the United States Army

text: Established by General Order 6, 27 November 2007. Consists of multifunctional logistics officers in the rank of captain and above, drawn from the Ordnance, Quartermaster and Transportation Corps.


title: Structure of the United States Army

text: The post of Adjutant General was established 16 June 1775, and has been continuously in operation since that time. The Adjutant General's Department, by that name, was established by the act of 3 March 1812, and was re-designated the Adjutant General's Corps in 1950.


title: Structure of the United States Army

text: The Finance Corps is the successor to the old Pay Department, which was created in June 1775. The Finance Department was created by law on 1 July 1920. It became the Finance Corps in 1950.


title: Structure of the United States Army

text: The Army Medical Department and the Medical Corps trace their origins to 27 July 1775, when the Continental Congress established the army hospital headed by a "Director General and Chief Physician." Congress provided a medical organization of the army only in time of war or emergency until 1818, which marked the inception of a permanent and continuous Medical Department. The Army Organization Act of 1950 renamed the Medical Department as the Army Medical Service. In June 1968, the Army Medical Service was re-designated the Army Medical Department. The Medical Department has the following branches:


title: Structure of the United States Army

text: The legal origin of the Chaplain Corps is found in a resolution of the Continental Congress, adopted 29 July 1775, which made provision for the pay of chaplains. The Office of the Chief of Chaplains was created by the National Defense Act of 1920.


title: Structure of the United States Army

text: The Office of Judge Advocate General of the Army is deemed to have been created on 29 July 1775, the date of appointment of Colonel William Tudor as the first U.S. Army Judge Advocate General. The history of the branch has generally paralleled the origin and development of the American system of military justice. The Judge Advocate General Department, by that name, was established in 1884. Its present designation as a corps was enacted in 1948.


title: Jim Messina (musician)

text: James Messina (born December 5, 1947) is an American musician, songwriter, singer, guitarist, recording engineer and record producer. He was a member of the folk rock group Buffalo Springfield, a founding member of the pioneering country rock band Poco, and half of the soft rock duo Loggins and Messina with Kenny Loggins.


title: Jim Messina (musician)

text: James Messina was born in Maywood, California, in 1947, and raised in Harlingen, Texas, until he was eight. He spent much of his childhood split between his father's home in California and his mother's home in Texas.


title: Jim Messina (musician)

text: His father was a guitarist and greatly influenced his son's musical career. Messina began playing the guitar at the age of five. He later became interested in the music of Elvis Presley and Ricky Nelson.


title: Jim Messina (musician)

text: When he was 16 years old, he recorded an LP with "His Jesters" titled "The Dragsters", which was released in November 1964. One notable track was "The Jester", on which he played lead guitar; it was included on the 2003 CD "Lost Legends of Surf Guitar Volume 1".


title: Jim Messina (musician)

text: While with Buffalo Springfield, Messina served as a recording engineer, producer, and musician, replacing bass player Bruce Palmer on two songs from their final album, "Last Time Around".


title: Jim Messina (musician)

text: After Buffalo Springfield disbanded, Messina and Richie Furay, a founding member of Buffalo Springfield, formed Poco in 1968. Switching back from bass to guitar, Messina played lead guitar and supplied vocals and some songwriting to the band. After recording two studio albums and one live album, he left Poco due to exhaustion from touring and to focus on becoming a record producer.


title: Jim Messina (musician)

text: After Poco, Messina signed a contract with Columbia Records as an independent producer. Messina was first introduced to the idea of producing Kenny Loggins in the summer of 1970 while still performing on the road with Poco. Loggins first met Messina in December 1970 at Messina's home, where the two recorded a number of Loggins' compositions in Messina's living room. Loggins at the time was a songwriter for ABC Dunhill and not a performing artist. Loggins had no agent, no manager, no business manager, and no prior experience as a performing artist. Messina felt Loggins needed some kind of an edge, and should embrace a more modern sound.


title: Jim Messina (musician)

text: In the course of deciding how to produce Loggins' first solo album, Messina met with Clive Davis, then president of Columbia Records. Messina proposed to Davis that he be allowed to sit in with Loggins on his first solo album in the same way that jazz artists had done in the past, and stated that Loggins also needed more upbeat and diverse material to help him gain appeal as a pop music artist. After reluctantly agreeing, Davis pursued the "Sitting In" concept through to the end.


title: Jim Messina (musician)

text: With music trends moving away from folk, Messina presented Loggins with a number of songs that spilled over from his days with Poco and Buffalo Springfield. He felt Loggins could do both country rock and R&B styles extremely well, especially after hearing Loggins perform "Danny's Song."


title: Jim Messina (musician)

text: Among the material Messina contributed was "Listen to a Country Song" (which would be a hit single for Lynn Anderson when she recorded it the following year), "Nobody But You," "Same Old Wine," and "The Trilogy," which included "Peace of Mind." He provided the rehearsal space, amps, and instruments and lent his talents as an arranger, vocalist, and guitarist. Messina worked long hours with Loggins and encouraged him to purchase an electric guitar and play it on his solo debut album.


title: Jim Messina (musician)

text: Messina assembled "The Kenny Loggins Band" by summoning old friends drummer Merel Bregante and bassist/singer Larry Sims (both formally of The Sunshine Company), multireedist/violinist Al Garth, multireedist Jon Clarke (performing with the Don Ellis Jazz Band), and a friend of Loggins, keyboardist Michael Omartian, who played on the album but dropped out once the touring began. However, Omartian played on the next two albums, and the ensemble was also augmented on each of their studio releases by Los Angeles-based session percussionist Milt Holland.


title: Jim Messina (musician)

text: Though the album was originally intended to be Loggins' first solo album, the two decided that Messina's contribution was so substantial that the album was finally released as "Kenny Loggins with Jim Messina Sittin' In", in November 1971. Messina had been reluctant to perform and tour, having begun the collaboration with the sole interest of producing. Nonetheless, by the end of 1972, the group, now renamed "Loggins and Messina", had toured extensively; they would eventually sell over 20 million albums.


title: Jim Messina (musician)

text: After the release of "Sittin' In", Messina went on to write, perform and produce seven more albums with Loggins. Those albums were "Loggins and Messina" (1972), "Full Sail" (1973), "On Stage" (1974), "Mother Lode" (1974), "So Fine" (1975, a covers album), "Native Sons" (1976, their last studio release) and "Finale" (1977, released by Columbia after the duo's split).


title: Jim Messina (musician)

text: Loggins ultimately decided to strike out on his own, and in 1976 the duo split after a final concert in Hawaii. Both went on to solo careers.


title: Jim Messina (musician)

text: In 1979, Messina met with Don Ellis (not to be confused with Don Ellis the jazz musician who recorded for the same label) of Columbia Records subsidiary A&R to plan his first solo album. He learned that Ellis did not like Messina's new musical direction, towards Latin jazz with a rock edge, because it did not sound like a Loggins and Messina album. Messina toured to support the debut LP, which sold 150,000 copies, about the same sales as "Sittin' In" had had. However, without the support of the record company, the album stalled, peaking at #58 on the Billboard 200, and Messina asked Columbia Records president Bruce Lundvall for a release from the label. Its single, "New And Different Way", slightly missed the Top 40 on the AC chart, peaking at #43.


title: Jim Messina (musician)

text: In 1981, Messina signed with Warner Bros. Records and recorded and released his second solo effort, "Messina", which included folk, rock, Latin and light jazz elements. The album featured singer Pauline Wilson, who sang a duet with Messina on "Stay the Night".


title: Jim Messina (musician)

text: In 1983, Messina released his third solo album with Warner Bros., "One More Mile". The album leaned more toward rock, and Messina used a number of young and upcoming studio musicians as his rhythm section. The album also featured Edie Laymen and Pauline Wilson singing background and harmony parts. On the song "The Island", he shows his influence of slack key, a Hawaiian style of playing the guitar.


title: Jim Messina (musician)

text: In 1993, Brooks and Dunn recorded "Mexican Minutes" written by Jim Messina and co-authored with Kent Robbins in Nashville.


title: Jim Messina (musician)

text: In 1989, Poco's original lineup (consisting of Messina, Richie Furay, Rusty Young, George Grantham and Randy Meisner) regrouped for a successful reunion tour. That same year, they released the album "Legacy". Messina played guitar and mandolin on the album. He wrote and sang on three of the songs: "Follow Your Dreams", "Look Within" and "Lovin' You Every Minute." He also co-wrote the song "Call It Love", which was sung by Rusty Young. That song reached number 18 on the Billboard Hot 100 in August 1989.


title: Jim Messina (musician)

text: In 2005, Messina and Loggins hit the road as a duo again. They had a successful nationwide tour that produced a CD and DVD entitled "". Messina also pulled from the vaults the original master analog recordings that he had produced and mixed for Loggins and Messina at Columbia Records, which were released as the 2005 digitally mastered compilation album "".


title: Jim Messina (musician)

text: In 2009, Messina released the CD "Under a Mojito Moon-Part 1", on which the only guitar he played was his flamenco guitar. The Latin-based arrangements feature trumpet, percussion, drums, piano and nylon acoustic guitar in melodies reminiscent of the music of Cuba and Spain.


title: Jim Messina (musician)

text: In 2012, Messina released the CD and DVD "Jim Messina LIVE at the Clark Center for the Performing Arts" containing songs by The Buffalo Springfield, Poco, Loggins & Messina as well as his solo material.


title: Jim Messina (musician)

text: He continues to work in the field of publishing, production and electronics as a recording and mixing engineer and as a recording studio owner, as well as performing on tour.


title: Jim Messina (musician)

text: He is both the creator and facilitator of "The Songwriters' Performance Workshop", wherein he leads 6-day intensive workshops for songwriters and singers at retreats, resorts and hotels around the country.


title: Jim Messina (musician)

text: In 1970, Messina married actress Jenny Sullivan; the marriage ended ten years later in 1980. They had no children. Messina has a son, recording engineer and musician Julian Messina (born 1992), from a relationship in the early 1990s. In 2001, Messina met his second wife, Michaela Laza Messina, an opera singer and a music teacher. They have a daughter, Josey (born 2006).


title: Evolutionary psychology

text: Evolutionary psychology is a theoretical approach in psychology that examines cognition and behavior from a modern evolutionary perspective. It seeks to identify which human psychological traits are evolved adaptations – that is, the functional products of natural selection or sexual selection in human evolution. Adaptationist thinking about physiological mechanisms, such as the heart, lungs, and immune system, is common in evolutionary biology. Some evolutionary psychologists apply the same thinking to psychology, arguing that the modularity of mind is similar to that of the body and with different modular adaptations serving different functions. These evolutionary psychologists argue that much of human behavior is the output of psychological adaptations that evolved to solve recurrent problems in human ancestral environments.


title: Evolutionary psychology

text: Some evolutionary psychologists argue that evolutionary theory can provide a foundational, metatheoretical framework that integrates the entire field of psychology in the same way evolutionary biology has for biology.


title: Evolutionary psychology

text: Evolutionary psychologists hold that behaviors or traits that occur universally in all cultures are good candidates for evolutionary adaptations, including the abilities to infer others' emotions, discern kin from non-kin, identify and prefer healthier mates, and cooperate with others. Findings have been made regarding human social behaviour related to infanticide, intelligence, marriage patterns, promiscuity, perception of beauty, bride price, and parental investment. The theories and findings of evolutionary psychology have applications in many fields, including economics, environment, health, law, management, psychiatry, politics, and literature.


title: Evolutionary psychology

text: Criticism of evolutionary psychology involves questions of testability, cognitive and evolutionary assumptions (such as modular functioning of the brain, and large uncertainty about the ancestral environment), importance of non-genetic and non-adaptive explanations, as well as political and ethical issues due to interpretations of research results.


title: Evolutionary psychology

text: Evolutionary psychology is an approach that views human nature as the product of a universal set of evolved psychological adaptations to recurring problems in the ancestral environment. Proponents suggest that it seeks to integrate psychology into the other natural sciences, rooting it in the organizing theory of biology (evolutionary theory), and thus understanding psychology as a branch of biology. Anthropologist John Tooby and psychologist Leda Cosmides note:


title: Evolutionary psychology

text: Just as human physiology and evolutionary physiology have worked to identify physical adaptations of the body that represent "human physiological nature," the purpose of evolutionary psychology is to identify evolved emotional and cognitive adaptations that represent "human psychological nature." According to Steven Pinker, it is "not a single theory but a large set of hypotheses" and a term that "has also come to refer to a particular way of applying evolutionary theory to the mind, with an emphasis on adaptation, gene-level selection, and modularity." Evolutionary psychology adopts an understanding of the mind that is based on the computational theory of mind. It describes mental processes as computational operations, so that, for example, a fear response is described as arising from a neurological computation that inputs the perceptional data, e.g. a visual image of a spider, and outputs the appropriate reaction, e.g. fear of possibly dangerous animals. Under this view, any domain-general learning is impossible because of the combinatorial explosion. Evolutionary Psychology specifies the domain as the problems of survival and reproduction.


title: Evolutionary psychology

text: While philosophers have generally considered the human mind to include broad faculties, such as reason and lust, evolutionary psychologists describe evolved psychological mechanisms as narrowly focused to deal with specific issues, such as catching cheaters or choosing mates. The discipline views the human brain as comprising many functional mechanisms called "psychological adaptations" or evolved cognitive mechanisms or "cognitive modules", designed by the process of natural selection. Examples include language-acquisition modules, incest-avoidance mechanisms, cheater-detection mechanisms, intelligence and sex-specific mating preferences, foraging mechanisms, alliance-tracking mechanisms, agent-detection mechanisms, and others. Some mechanisms, termed "domain-specific", deal with recurrent adaptive problems over the course of human evolutionary history. "Domain-general" mechanisms, on the other hand, are proposed to deal with evolutionary novelty.


title: Evolutionary psychology

text: Evolutionary psychology has roots in cognitive psychology and evolutionary biology but also draws on behavioral ecology, artificial intelligence, genetics, ethology, anthropology, archaeology, biology, and zoology. It is closely linked to sociobiology, but there are key differences between them including the emphasis on "domain-specific" rather than "domain-general" mechanisms, the relevance of measures of current fitness, the importance of mismatch theory, and psychology rather than behavior.


title: Evolutionary psychology

text: Nikolaas Tinbergen's four categories of questions can help to clarify the distinctions between several different, but complementary, types of explanations. Evolutionary psychology focuses primarily on the "why?" questions, while traditional psychology focuses on the "how?" questions.


title: Evolutionary psychology

text: Evolutionary psychology has its historical roots in Charles Darwin's theory of natural selection. In "The Origin of Species", Darwin predicted that psychology would develop an evolutionary basis:


title: Evolutionary psychology

text: Two of his later books were devoted to the study of animal emotions and psychology; "The Descent of Man, and Selection in Relation to Sex" in 1871 and "The Expression of the Emotions in Man and Animals" in 1872. Darwin's work inspired William James's functionalist approach to psychology. Darwin's theories of evolution, adaptation, and natural selection have provided insight into why brains function the way they do.


title: Evolutionary psychology

text: The content of evolutionary psychology has derived from, on the one hand, the biological sciences (especially evolutionary theory as it relates to ancient human environments, the study of paleoanthropology and animal behavior) and, on the other, the human sciences, especially psychology.


title: Evolutionary psychology

text: Evolutionary biology as an academic discipline emerged with the modern synthesis in the 1930s and 1940s. In the 1930s the study of animal behavior (ethology) emerged with the work of the Dutch biologist Nikolaas Tinbergen and the Austrian biologists Konrad Lorenz and Karl von Frisch.


title: Evolutionary psychology

text: W.D. Hamilton's (1964) papers on inclusive fitness and Robert Trivers's (1972) theories on reciprocity and parental investment helped to establish evolutionary thinking in psychology and the other social sciences. In 1975, Edward O. Wilson combined evolutionary theory with studies of animal and social behavior, building on the works of Lorenz and Tinbergen, in his book "".


title: Evolutionary psychology

text: In the 1970s, two major branches developed from ethology. Firstly, the study of animal "social" behavior (including humans) generated sociobiology, defined by its pre-eminent proponent Edward O. Wilson in 1975 as "the systematic study of the biological basis of all social behavior" and in 1978 as "the extension of population biology and evolutionary theory to social organization." Secondly, there was behavioral ecology which placed less emphasis on "social" behavior; it focused on the ecological and evolutionary basis of animal and human behavior.


title: Evolutionary psychology

text: In the 1970s and 1980s university departments began to include the term "evolutionary biology" in their titles. The modern era of evolutionary psychology was ushered in, in particular, by Donald Symons' 1979 book "The Evolution of Human Sexuality" and Leda Cosmides and John Tooby's 1992 book "The Adapted Mind". David Buller observed that the term "evolutionary psychology" is sometimes seen as denoting research based on the specific methodological and theoretical commitments of certain researchers from the Santa Barbara school (University of California), thus some evolutionary psychologists prefer to term their work "human ecology", "human behavioural ecology" or "evolutionary anthropology" instead.


title: Evolutionary psychology

text: From psychology there are the primary streams of developmental, social and cognitive psychology. Establishing some measure of the relative influence of genetics and environment on behavior has been at the core of behavioral genetics and its variants, notably studies at the molecular level that examine the relationship between genes, neurotransmitters and behavior. Dual inheritance theory (DIT), developed in the late 1970s and early 1980s, has a slightly different perspective by trying to explain how human behavior is a product of two different and interacting evolutionary processes: genetic evolution and cultural evolution. DIT is seen by some as a "middle-ground" between views that emphasize human universals versus those that emphasize cultural variation.


title: Evolutionary psychology

text: The theories on which evolutionary psychology is based originated with Charles Darwin's work, including his speculations about the evolutionary origins of social instincts in humans. Modern evolutionary psychology, however, is possible only because of advances in evolutionary theory in the 20th century.


title: Evolutionary psychology

text: Evolutionary psychologists say that natural selection has provided humans with many psychological adaptations, in much the same way that it generated humans' anatomical and physiological adaptations. As with adaptations in general, psychological adaptations are said to be specialized for the environment in which an organism evolved, the environment of evolutionary adaptedness. Sexual selection provides organisms with adaptations related to mating. For male mammals, which have a relatively high maximal potential reproduction rate, sexual selection leads to adaptations that help them compete for females. For female mammals, with a relatively low maximal potential reproduction rate, sexual selection leads to choosiness, which helps females select higher quality mates. Charles Darwin described both natural selection and sexual selection, and he relied on group selection to explain the evolution of altruistic (self-sacrificing) behavior. But group selection was considered a weak explanation, because in any group the less altruistic individuals will be more likely to survive, and the group will become less self-sacrificing as a whole.


title: Evolutionary psychology

text: In 1964, the evolutionary biologist William D. Hamilton proposed inclusive fitness theory, emphasizing a gene-centered view of evolution. Hamilton noted that genes can increase the replication of copies of themselves into the next generation by influencing the organism's social traits in such a way that (statistically) results in helping the survival and reproduction of other copies of the same genes (most simply, identical copies in the organism's close relatives). According to Hamilton's rule, self-sacrificing behaviors (and the genes influencing them) can evolve if they typically help the organism's close relatives so much that it more than compensates for the individual animal's sacrifice. Inclusive fitness theory resolved the issue of how altruism can evolve. Other theories also help explain the evolution of altruistic behavior, including evolutionary game theory, tit-for-tat reciprocity, and generalized reciprocity. These theories help to explain the development of altruistic behavior, and account for hostility toward cheaters (individuals that take advantage of others' altruism).


title: Evolutionary psychology

text: Several mid-level evolutionary theories inform evolutionary psychology. The r/K selection theory proposes that some species prosper by having many offspring, while others follow the strategy of having fewer offspring but investing much more in each one. Humans follow the second strategy. Parental investment theory explains how parents invest more or less in individual offspring based on how successful those offspring are likely to be, and thus how much they might improve the parents' inclusive fitness. According to the Trivers–Willard hypothesis, parents in good conditions tend to invest more in sons (who are best able to take advantage of good conditions), while parents in poor conditions tend to invest more in daughters (who are best able to have successful offspring even in poor conditions). According to life history theory, animals evolve life histories to match their environments, determining details such as age at first reproduction and number of offspring. Dual inheritance theory posits that genes and human culture have interacted, with genes affecting the development of culture, and culture, in turn, affecting human evolution on a genetic level, in a similar way to the Baldwin effect.


title: Evolutionary psychology

text: Evolutionary psychology is based on the hypothesis that, just like hearts, lungs, livers, kidneys, and immune systems, cognition has a functional structure that has a genetic basis, and therefore has evolved by natural selection. Like other organs and tissues, this functional structure should be universally shared amongst a species and should solve important problems of survival and reproduction.


title: Evolutionary psychology

text: Evolutionary psychologists seek to understand psychological mechanisms by understanding the survival and reproductive functions they might have served over the course of evolutionary history. These might include abilities to infer others' emotions, discern kin from non-kin, identify and prefer healthier mates, cooperate with others and follow leaders. Consistent with the theory of natural selection, evolutionary psychology sees humans as often in conflict with others, including mates and relatives. For instance, a mother may wish to wean her offspring from breastfeeding earlier than does her infant, which frees up the mother to invest in additional offspring. Evolutionary psychology also recognizes the role of kin selection and reciprocity in evolving prosocial traits such as altruism. Like chimpanzees and bonobos, humans have subtle and flexible social instincts, allowing them to form extended families, lifelong friendships, and political alliances. In studies testing theoretical predictions, evolutionary psychologists have made modest findings on topics such as infanticide, intelligence, marriage patterns, promiscuity, perception of beauty, bride price and parental investment.


title: Evolutionary psychology

text: Another example would be the evolved mechanism in depression. Clinical depression is maladaptive and should have evolutionary approaches so it can become adaptive. Over the centuries animals and humans have gone through hard times to stay alive, which made our fight or flight senses evolve tremendously. For instances, mammalians have separation anxiety from their guardians which causes distress and sends signals to their hypothalamic pituitary adrenal axis, and emotional/behavioral changes. Going through these types of circumstances helps mammals cope with separation anxiety.


title: Evolutionary psychology

text: Proponents of evolutionary psychology in the 1990s made some explorations in historical events, but the response from historical experts was highly negative and there has been little effort to continue that line of research. Historian Lynn Hunt says that the historians complained that the researchers:


title: Evolutionary psychology

text: Hunt states that "the few attempts to build up a subfield of psychohistory collapsed under the weight of its presuppositions." She concludes that as of 2014 the "'iron curtain' between historians and psychology...remains standing."


title: Evolutionary psychology

text: Not all traits of organisms are evolutionary adaptations. As noted in the table below, traits may also be exaptations, byproducts of adaptations (sometimes called "spandrels"), or random variation between individuals.


title: Evolutionary psychology

text: Psychological adaptations are hypothesized to be innate or relatively easy to learn and to manifest in cultures worldwide. For example, the ability of toddlers to learn a language with virtually no training is likely to be a psychological adaptation. On the other hand, ancestral humans did not read or write, thus today, learning to read and write requires extensive training, and presumably involves the repurposing of cognitive capacities that evolved in response to selection pressures unrelated to written language. However, variations in manifest behavior can result from universal mechanisms interacting with different local environments. For example, Caucasians who move from a northern climate to the equator will have darker skin. The mechanisms regulating their pigmentation do not change; rather the input to those mechanisms change, resulting in different outputs.


title: Evolutionary psychology

text: One of the tasks of evolutionary psychology is to identify which psychological traits are likely to be adaptations, byproducts or random variation. George C. Williams suggested that an "adaptation is a special and onerous concept that should only be used where it is really necessary." As noted by Williams and others, adaptations can be identified by their improbable complexity, species universality, and adaptive functionality.


title: Evolutionary psychology

text: A question that may be asked about an adaptation is whether it is generally obligate (relatively robust in the face of typical environmental variation) or facultative (sensitive to typical environmental variation). The sweet taste of sugar and the pain of hitting one's knee against concrete are the result of fairly obligate psychological adaptations; typical environmental variability during development does not much affect their operation. By contrast, facultative adaptations are somewhat like "if-then" statements. For example, The adaptation for skin to tan is conditional to exposure to sunlight; this is an example of another facultative adaptation. When a psychological adaptation is facultative, evolutionary psychologists concern themselves with how developmental and environmental inputs influence the expression of the adaptation.


title: Evolutionary psychology

text: Evolutionary psychologists hold that behaviors or traits that occur universally in all cultures are good candidates for evolutionary adaptations. Cultural universals include behaviors related to language, cognition, social roles, gender roles, and technology. Evolved psychological adaptations (such as the ability to learn a language) interact with cultural inputs to produce specific behaviors (e.g., the specific language learned).


title: Evolutionary psychology

text: Basic gender differences, such as greater eagerness for sex among men and greater coyness among women, are explained as sexually dimorphic psychological adaptations that reflect the different reproductive strategies of males and females.


title: Evolutionary psychology

text: Evolutionary psychologists contrast their approach to what they term the "standard social science model," according to which the mind is a general-purpose cognition device shaped almost entirely by culture.


title: Evolutionary psychology

text: Evolutionary psychology argues that to properly understand the functions of the brain, one must understand the properties of the environment in which the brain evolved. That environment is often referred to as the "environment of evolutionary adaptedness".


title: Evolutionary psychology

text: The idea of an "environment of evolutionary adaptedness" was first explored as a part of attachment theory by John Bowlby. This is the environment to which a particular evolved mechanism is adapted. More specifically, the environment of evolutionary adaptedness is defined as the set of historically recurring selection pressures that formed a given adaptation, as well as those aspects of the environment that were necessary for the proper development and functioning of the adaptation.


title: Evolutionary psychology

text: Humans, comprising the genus "Homo", appeared between 1.5 and 2.5 million years ago, a time that roughly coincides with the start of the Pleistocene 2.6 million years ago. Because the Pleistocene ended a mere 12,000 years ago, most human adaptations either newly evolved during the Pleistocene, or were maintained by stabilizing selection during the Pleistocene. Evolutionary psychology, therefore, proposes that the majority of human psychological mechanisms are adapted to reproductive problems frequently encountered in Pleistocene environments. In broad terms, these problems include those of growth, development, differentiation, maintenance, mating, parenting, and social relationships.


title: Evolutionary psychology

text: The environment of evolutionary adaptedness is significantly different from modern society. The ancestors of modern humans lived in smaller groups, had more cohesive cultures, and had more stable and rich contexts for identity and meaning. Researchers look to existing hunter-gatherer societies for clues as to how hunter-gatherers lived in the environment of evolutionary adaptedness. Unfortunately, the few surviving hunter-gatherer societies are different from each other, and they have been pushed out of the best land and into harsh environments, so it is not clear how closely they reflect ancestral culture. However, all around the world small-band hunter-gatherers offer a similar developmental system for the young ("hunter-gatherer childhood model," Konner, 2005;


title: Evolutionary psychology

text: "evolved developmental niche" or "evolved nest;" Narvaez et al., 2013). The characteristics of the niche are largely the same as for social mammals, who evolved over 30 million years ago: soothing perinatal experience, several years of on-request breastfeeding, nearly constant affection or physical proximity, responsiveness to need (mitigating offspring distress), self-directed play, and for humans, multiple responsive caregivers. Initial studies show the importance of these components in early life for positive child outcomes.


title: Evolutionary psychology

text: Evolutionary psychologists sometimes look to chimpanzees, bonobos, and other great apes for insight into human ancestral behavior.


title: Evolutionary psychology

text: Since an organism's adaptations were suited to its ancestral environment, a new and different environment can create a mismatch. Because humans are mostly adapted to Pleistocene environments, psychological mechanisms sometimes exhibit "mismatches" to the modern environment. One example is the fact that although about 10,000 people are killed with guns in the US annually, whereas spiders and snakes kill only a handful, people nonetheless learn to fear spiders and snakes about as easily as they do a pointed gun, and more easily than an unpointed gun, rabbits or flowers. A potential explanation is that spiders and snakes were a threat to human ancestors throughout the Pleistocene, whereas guns (and rabbits and flowers) were not. There is thus a mismatch between humans' evolved fear-learning psychology and the modern environment.


title: Evolutionary psychology

text: This mismatch also shows up in the phenomena of the supernormal stimulus, a stimulus that elicits a response more strongly than the stimulus for which the response evolved. The term was coined by Niko Tinbergen to refer to non-human animal behavior, but psychologist Deirdre Barrett said that supernormal stimulation governs the behavior of humans as powerfully as that of other animals. She explained junk food as an exaggerated stimulus to cravings for salt, sugar, and fats, and she says that television is an exaggeration of social cues of laughter, smiling faces and attention-grabbing action. Magazine centerfolds and double cheeseburgers pull instincts intended for an environment of evolutionary adaptedness where breast development was a sign of health, youth and fertility in a prospective mate, and fat was a rare and vital nutrient. The psychologist Mark van Vugt recently argued that modern organizational leadership is a mismatch. His argument is that humans are not adapted to work in large, anonymous bureaucratic structures with formal hierarchies. The human mind still responds to personalized, charismatic leadership primarily in the context of informal, egalitarian settings. Hence the dissatisfaction and alienation that many employees experience. Salaries, bonuses and other privileges exploit instincts for relative status, which attract particularly males to senior executive positions.


title: Evolutionary psychology

text: Evolutionary theory is heuristic in that it may generate hypotheses that might not be developed from other theoretical approaches. One of the major goals of adaptationist research is to identify which organismic traits are likely to be adaptations, and which are byproducts or random variations. As noted earlier, adaptations are expected to show evidence of complexity, functionality, and species universality, while byproducts or random variation will not. In addition, adaptations are expected to manifest as proximate mechanisms that interact with the environment in either a generally obligate or facultative fashion (see above). Evolutionary psychologists are also interested in identifying these proximate mechanisms (sometimes termed "mental mechanisms" or "psychological adaptations") and what type of information they take as input, how they process that information, and their outputs. Evolutionary developmental psychology, or "evo-devo," focuses on how adaptations may be activated at certain developmental times (e.g., losing baby teeth, adolescence, etc.) or how events during the development of an individual may alter life-history trajectories.


title: Evolutionary psychology

text: Evolutionary psychologists use several strategies to develop and test hypotheses about whether a psychological trait is likely to be an evolved adaptation. Buss (2011) notes that these methods include:


title: Evolutionary psychology

text: Evolutionary psychologists also use various sources of data for testing, including experiments, archaeological records, data from hunter-gatherer societies, observational studies, neuroscience data, self-reports and surveys, public records, and human products.


title: Evolutionary psychology

text: Recently, additional methods and tools have been introduced based on fictional scenarios, mathematical models, and multi-agent computer simulations.


title: Evolutionary psychology

text: Foundational areas of research in evolutionary psychology can be divided into broad categories of adaptive problems that arise from evolutionary theory itself: survival, mating, parenting, family and kinship, interactions with non-kin, and cultural evolution.


title: Evolutionary psychology

text: Problems of survival are clear targets for the evolution of physical and psychological adaptations. Major problems the ancestors of present-day humans faced included food selection and acquisition; territory selection and physical shelter; and avoiding predators and other environmental threats.


title: Evolutionary psychology

text: Consciousness meets George Williams' criteria of species universality, complexity, and functionality, and it is a trait that apparently increases fitness.


title: Evolutionary psychology

text: In his paper "Evolution of consciousness," John Eccles argues that special anatomical and physical adaptations of the mammalian cerebral cortex gave rise to consciousness. In contrast, others have argued that the recursive circuitry underwriting consciousness is much more primitive, having evolved initially in pre-mammalian species because it improves the capacity for interaction with both social "and" natural environments by providing an energy-saving "neutral" gear in an otherwise energy-expensive motor output machine. Once in place, this recursive circuitry may well have provided a basis for the subsequent development of many of the functions that consciousness facilitates in higher organisms, as outlined by Bernard J. Baars. Richard Dawkins suggested that humans evolved consciousness in order to make themselves the subjects of thought. Daniel Povinelli suggests that large, tree-climbing apes evolved consciousness to take into account one's own mass when moving safely among tree branches. Consistent with this hypothesis, Gordon Gallup found that chimpanzees and orangutans, but not little monkeys or terrestrial gorillas, demonstrated self-awareness in mirror tests.


title: Evolutionary psychology

text: The concept of consciousness can refer to voluntary action, awareness, or wakefulness. However, even voluntary behavior involves unconscious mechanisms. Many cognitive processes take place in the cognitive unconscious, unavailable to conscious awareness. Some behaviors are conscious when learned but then become unconscious, seemingly automatic. Learning, especially implicitly learning a skill, can take place outside of consciousness. For example, plenty of people know how to turn right when they ride a bike, but very few can accurately explain how they actually do so. Evolutionary psychology approaches self-deception as an adaptation that can improve one's results in social exchanges.


title: Evolutionary psychology

text: Sleep may have evolved to conserve energy when activity would be less fruitful or more dangerous, such as at night, and especially during the winter season.


title: Evolutionary psychology

text: Many experts, such as Jerry Fodor, write that the purpose of perception is knowledge, but evolutionary psychologists hold that its primary purpose is to guide action. For example, they say, depth perception seems to have evolved not to help us know the distances to other objects but rather to help us move around in space. Evolutionary psychologists say that animals from fiddler crabs to humans use eyesight for collision avoidance, suggesting that vision is basically for directing action, not providing knowledge.


title: Evolutionary psychology

text: Building and maintaining sense organs is metabolically expensive, so these organs evolve only when they improve an organism's fitness. More than half the brain is devoted to processing sensory information, and the brain itself consumes roughly one-fourth of one's metabolic resources, so the senses must provide exceptional benefits to fitness. Perception accurately mirrors the world; animals get useful, accurate information through their senses.


title: Evolutionary psychology

text: Scientists who study perception and sensation have long understood the human senses as adaptations to their surrounding worlds. Depth perception consists of processing over half a dozen visual cues, each of which is based on a regularity of the physical world. Vision evolved to respond to the narrow range of electromagnetic energy that is plentiful and that does not pass through objects. Sound waves go around corners and interact with obstacles, creating a complex pattern that includes useful information about the sources of and distances to objects. Larger animals naturally make lower-pitched sounds as a consequence of their size. The range over which an animal hears, on the other hand, is determined by adaptation. Homing pigeons, for example, can hear the very low-pitched sound (infrasound) that carries great distances, even though most smaller animals detect higher-pitched sounds. Taste and smell respond to chemicals in the environment that are thought to have been significant for fitness in the environment of evolutionary adaptedness. For example, salt and sugar were apparently both valuable to the human or pre-human inhabitants of the environment of evolutionary adaptedness, so present-day humans have an intrinsic hunger for salty and sweet tastes. The sense of touch is actually many senses, including pressure, heat, cold, tickle, and pain. Pain, while unpleasant, is adaptive. An important adaptation for senses is range shifting, by which the organism becomes temporarily more or less sensitive to sensation. For example, one's eyes automatically adjust to dim or bright ambient light. Sensory abilities of different organisms often coevolve, as is the case with the hearing of echolocating bats and that of the moths that have evolved to respond to the sounds that the bats make.


title: Evolutionary psychology

text: Evolutionary psychologists contend that perception demonstrates the principle of modularity, with specialized mechanisms handling particular perception tasks. For example, people with damage to a particular part of the brain have the specific defect of not being able to recognize faces (prosopagnosia). Evolutionary psychology suggests that this indicates a so-called face-reading module.


title: Evolutionary psychology

text: In evolutionary psychology, learning is said to be accomplished through evolved capacities, specifically facultative adaptations. Facultative adaptations express themselves differently depending on input from the environment. Sometimes the input comes during development and helps shape that development. For example, migrating birds learn to orient themselves by the stars during a critical period in their maturation. Evolutionary psychologists believe that humans also learn language along an evolved program, also with critical periods. The input can also come during daily tasks, helping the organism cope with changing environmental conditions. For example, animals evolved Pavlovian conditioning in order to solve problems about causal relationships. Animals accomplish learning tasks most easily when those tasks resemble problems that they faced in their evolutionary past, such as a rat learning where to find food or water. Learning capacities sometimes demonstrate differences between the sexes. In many animal species, for example, males can solve spatial problems faster and more accurately than females, due to the effects of male hormones during development. The same might be true of humans.


title: Evolutionary psychology

text: Motivations direct and energize behavior, while emotions provide the affective component to motivation, positive or negative. In the early 1970s, Paul Ekman and colleagues began a line of research which suggests that many emotions are universal. He found evidence that humans share at least five basic emotions: fear, sadness, happiness, anger, and disgust. Social emotions evidently evolved to motivate social behaviors that were adaptive in the environment of evolutionary adaptedness. For example, spite seems to work against the individual but it can establish an individual's reputation as someone to be feared. Shame and pride can motivate behaviors that help one maintain one's standing in a community, and self-esteem is one's estimate of one's status.


title: Evolutionary psychology

text: Motivation has a neurobiological basis in the reward system of the brain. Recently, it has been suggested that reward systems may evolve in such a way that there may be an inherent or unavoidable trade-off in the motivational system for activities of short versus long duration.


title: Evolutionary psychology

text: Cognition refers to internal representations of the world and internal information processing. From an evolutionary psychology perspective, cognition is not "general purpose," but uses heuristics, or strategies, that generally increase the likelihood of solving problems that the ancestors of present-day humans routinely faced. For example, present-day humans are far more likely to solve logic problems that involve detecting cheating (a common problem given humans' social nature) than the same logic problem put in purely abstract terms. Since the ancestors of present-day humans did not encounter truly random events, present-day humans may be cognitively predisposed to incorrectly identify patterns in random sequences. "Gamblers' Fallacy" is one example of this. Gamblers may falsely believe that they have hit a "lucky streak" even when each outcome is actually random and independent of previous trials. Most people believe that if a fair coin has been flipped 9 times and Heads appears each time, that on the tenth flip, there is a greater than 50% chance of getting Tails. Humans find it far easier to make diagnoses or predictions using frequency data than when the same information is presented as probabilities or percentages, presumably because the ancestors of present-day humans lived in relatively small tribes (usually with fewer than 150 people) where frequency information was more readily available.


title: Evolutionary psychology

text: Evolutionary psychology is primarily interested in finding commonalities between people, or basic human psychological nature. From an evolutionary perspective, the fact that people have fundamental differences in personality traits initially presents something of a puzzle. (Note: The field of behavioral genetics is concerned with statistically partitioning differences between people into genetic and environmental sources of variance. However, understanding the concept of heritability can be tricky – heritability refers only to the differences between people, never the degree to which the traits of an individual are due to environmental or genetic factors, since traits are always a complex interweaving of both.)


title: Evolutionary psychology

text: Personality traits are conceptualized by evolutionary psychologists as due to normal variation around an optimum, due to frequency-dependent selection (behavioral polymorphisms), or as facultative adaptations. Like variability in height, some personality traits may simply reflect inter-individual variability around a general optimum. Or, personality traits may represent different genetically predisposed "behavioral morphs" – alternate behavioral strategies that depend on the frequency of competing behavioral strategies in the population. For example, if most of the population is generally trusting and gullible, the behavioral morph of being a "cheater" (or, in the extreme case, a sociopath) may be advantageous. Finally, like many other psychological adaptations, personality traits may be facultative – sensitive to typical variations in the social environment, especially during early development. For example, later-born children are more likely than firstborns to be rebellious, less conscientious and more open to new experiences, which may be advantageous to them given their particular niche in family structure. It is important to note that shared environmental influences do play a role in personality and are not always of less importance than genetic factors. However, shared environmental influences often decrease to near zero after adolescence but do not completely disappear.


title: Evolutionary psychology

text: According to Steven Pinker, who builds on the work by Noam Chomsky, the universal human ability to learn to talk between the ages of 1 – 4, basically without training, suggests that language acquisition is a distinctly human psychological adaptation (see, in particular, Pinker's "The Language Instinct"). Pinker and Bloom (1990) argue that language as a mental faculty shares many likenesses with the complex organs of the body which suggests that, like these organs, language has evolved as an adaptation, since this is the only known mechanism by which such complex organs can develop.


title: Evolutionary psychology

text: Pinker follows Chomsky in arguing that the fact that children can learn any human language with no explicit instruction suggests that language, including most of grammar, is basically innate and that it only needs to be activated by interaction. Chomsky himself does not believe language to have evolved as an adaptation, but suggests that it likely evolved as a byproduct of some other adaptation, a so-called spandrel. But Pinker and Bloom argue that the organic nature of language strongly suggests that it has an adaptational origin.


title: Evolutionary psychology

text: Evolutionary psychologists hold that the FOXP2 gene may well be associated with the evolution of human language. In the 1980s, psycholinguist Myrna Gopnik identified a dominant gene that causes language impairment in the KE family of Britain. This gene turned out to be a mutation of the FOXP2 gene. Humans have a unique allele of this gene, which has otherwise been closely conserved through most of mammalian evolutionary history. This unique allele seems to have first appeared between 100 and 200 thousand years ago, and it is now all but universal in humans. However, the once-popular idea that FOXP2 is a 'grammar gene' or that it triggered the emergence of language in "Homo sapiens" is now widely discredited.


title: Evolutionary psychology

text: Currently, several competing theories about the evolutionary origin of language coexist, none of them having achieved a general consensus. Researchers of language acquisition in primates and humans such as Michael Tomasello and Talmy Givón, argue that the innatist framework has understated the role of imitation in learning and that it is not at all necessary to posit the existence of an innate grammar module to explain human language acquisition. Tomasello argues that studies of how children and primates actually acquire communicative skills suggest that humans learn complex behavior through experience, so that instead of a module specifically dedicated to language acquisition, language is acquired by the same cognitive mechanisms that are used to acquire all other kinds of socially transmitted behavior.


title: Evolutionary psychology

text: On the issue of whether language is best seen as having evolved as an adaptation or as a spandrel, evolutionary biologist W. Tecumseh Fitch, following Stephen J. Gould, argues that it is unwarranted to assume that every aspect of language is an adaptation, or that language as a whole is an adaptation. He criticizes some strands of evolutionary psychology for suggesting a pan-adaptionist view of evolution, and dismisses Pinker and Bloom's question of whether "Language has evolved as an adaptation" as being misleading. He argues instead that from a biological viewpoint the evolutionary origins of language is best conceptualized as being the probable result of a convergence of many separate adaptations into a complex system. A similar argument is made by Terrence Deacon who in "The Symbolic Species" argues that the different features of language have co-evolved with the evolution of the mind and that the ability to use symbolic communication is integrated in all other cognitive processes.


title: Evolutionary psychology

text: If the theory that language could have evolved as a single adaptation is accepted, the question becomes which of its many functions has been the basis of adaptation. Several evolutionary hypotheses have been posited: that language evolved for the purpose of social grooming, that it evolved as a way to show mating potential or that it evolved to form social contracts. Evolutionary psychologists recognize that these theories are all speculative and that much more evidence is required to understand how language might have been selectively adapted.


title: Evolutionary psychology

text: Given that sexual reproduction is the means by which genes are propagated into future generations, sexual selection plays a large role in human evolution. Human mating, then, is of interest to evolutionary psychologists who aim to investigate evolved mechanisms to attract and secure mates. Several lines of research have stemmed from this interest, such as studies of mate selection mate poaching, mate retention, mating preferences and conflict between the sexes.


title: Evolutionary psychology

text: In 1972 Robert Trivers published an influential paper on sex differences that is now referred to as parental investment theory. The size differences of gametes (anisogamy) is the fundamental, defining difference between males (small gametes – sperm) and females (large gametes – ova). Trivers noted that anisogamy typically results in different levels of parental investment between the sexes, with females initially investing more. Trivers proposed that this difference in parental investment leads to the sexual selection of different reproductive strategies between the sexes and to sexual conflict. For example, he suggested that the sex that invests less in offspring will generally compete for access to the higher-investing sex to increase their inclusive fitness (also see Bateman's principle<ref name="doi10.1038/hdy.1948.21"></ref>). Trivers posited that differential parental investment led to the evolution of sexual dimorphisms in mate choice, intra- and inter- sexual reproductive competition, and courtship displays. In mammals, including humans, females make a much larger parental investment than males (i.e. gestation followed by childbirth and lactation). Parental investment theory is a branch of life history theory.


title: Evolutionary psychology

text: Buss and Schmitt's (1993) "Sexual Strategies Theory" proposed that, due to differential parental investment, humans have evolved sexually dimorphic adaptations related to "sexual accessibility, fertility assessment, commitment seeking and avoidance, immediate and enduring resource procurement, paternity certainty, assessment of mate value, and parental investment." Their "Strategic Interference Theory" suggested that conflict between the sexes occurs when the preferred reproductive strategies of one sex interfere with those of the other sex, resulting in the activation of emotional responses such as anger or jealousy.


title: Evolutionary psychology

text: Women are generally more selective when choosing mates, especially under long-term mating conditions. However, under some circumstances, short term mating can provide benefits to women as well, such as fertility insurance, trading up to better genes, reducing the risk of inbreeding, and insurance protection of her offspring.


title: Evolutionary psychology

text: Due to male paternity insecurity, sex differences have been found in the domains of sexual jealousy. Females generally react more adversely to emotional infidelity and males will react more to sexual infidelity. This particular pattern is predicted because the costs involved in mating for each sex are distinct. Women, on average, should prefer a mate who can offer resources (e.g., financial, commitment), thus, a woman risks losing such resources with a mate who commits emotional infidelity. Men, on the other hand, are never certain of the genetic paternity of their children because they do not bear the offspring themselves ("paternity insecurity"). This suggests that for men sexual infidelity would generally be more aversive than emotional infidelity because investing resources in another man's offspring does not lead to the propagation of their own genes.


title: Evolutionary psychology

text: Another interesting line of research is that which examines women's mate preferences across the ovulatory cycle. The theoretical underpinning of this research is that ancestral women would have evolved mechanisms to select mates with certain traits depending on their hormonal status. Known as the ovulatory shift hypothesis, the theory posits that, during the ovulatory phase of a woman's cycle (approximately days 10–15 of a woman's cycle), a woman who mated with a male with high genetic quality would have been more likely, on average, to produce and bear a healthy offspring than a woman who mated with a male with low genetic quality. These putative preferences are predicted to be especially apparent for short-term mating domains because a potential male mate would only be offering genes to a potential offspring. This hypothesis allows researchers to examine whether women select mates who have characteristics that indicate high genetic quality during the high fertility phase of their ovulatory cycles. Indeed, studies have shown that women's preferences vary across the ovulatory cycle. In particular, Haselton and Miller (2006) showed that highly fertile women prefer creative but poor men as short-term mates. Creativity may be a proxy for good genes. Research by Gangestad et al. (2004) indicates that highly fertile women prefer men who display social presence and intrasexual competition; these traits may act as cues that would help women predict which men may have, or would be able to acquire, resources.


title: Evolutionary psychology

text: Reproduction is always costly for women, and can also be for men. Individuals are limited in the degree to which they can devote time and resources to producing and raising their young, and such expenditure may also be detrimental to their future condition, survival and further reproductive output.


title: Evolutionary psychology

text: Parental investment is any parental expenditure (time, energy etc.) that benefits one offspring at a cost to parents' ability to invest in other components of fitness (Clutton-Brock 1991: 9; Trivers 1972). Components of fitness (Beatty 1992) include the well-being of existing offspring, parents' future reproduction, and inclusive fitness through aid to kin (Hamilton, 1964). Parental investment theory is a branch of life history theory.


title: Evolutionary psychology

text: The benefits of parental investment to the offspring are large and are associated with the effects on condition, growth, survival, and ultimately, on the reproductive success of the offspring. However, these benefits can come at the cost of the parent's ability to reproduce in the future e.g. through the increased risk of injury when defending offspring against predators, the loss of mating opportunities whilst rearing offspring, and an increase in the time to the next reproduction. Overall, parents are selected to maximize the difference between the benefits and the costs, and parental care will likely evolve when the benefits exceed the costs.


title: Evolutionary psychology

text: The Cinderella effect is an alleged high incidence of stepchildren being physically, emotionally or sexually abused, neglected, murdered, or otherwise mistreated at the hands of their stepparents at significantly higher rates than their genetic counterparts. It takes its name from the fairy tale character Cinderella, who in the story was cruelly mistreated by her stepmother and stepsisters. Daly and Wilson (1996) noted: "Evolutionary thinking led to the discovery of the most important risk factor for child homicide – the presence of a stepparent. Parental efforts and investments are valuable resources, and selection favors those parental psyches that allocate effort effectively to promote fitness. The adaptive problems that challenge parental decision-making include both the accurate identification of one's offspring and the allocation of one's resources among them with sensitivity to their needs and abilities to convert parental investment into fitness increments…. Stepchildren were seldom or never so valuable to one's expected fitness as one's own offspring would be, and those parental psyches that were easily parasitized by just any appealing youngster must always have incurred a selective disadvantage"(Daly & Wilson, 1996, pp. 64–65). However, they note that not all stepparents will "want" to abuse their partner's children, or that genetic parenthood is any insurance against abuse. They see step parental care as primarily "mating effort" towards the genetic parent.


title: Evolutionary psychology

text: Inclusive fitness is the sum of an organism's classical fitness (how many of its own offspring it produces and supports) and the number of equivalents of its own offspring it can add to the population by supporting others. The first component is called classical fitness by Hamilton (1964).


title: Evolutionary psychology

text: From the gene's point of view, evolutionary success ultimately depends on leaving behind the maximum number of copies of itself in the population. Until 1964, it was generally believed that genes only achieved this by causing the individual to leave the maximum number of viable offspring. However, in 1964 W. D. Hamilton proved mathematically that, because close relatives of an organism share some identical genes, a gene can also increase its evolutionary success by promoting the reproduction and survival of these related or otherwise similar individuals. Hamilton concluded that this leads natural selection to favor organisms that would behave in ways that maximize their inclusive fitness. It is also true that natural selection favors behavior that maximizes personal fitness.


title: Evolutionary psychology

text: Hamilton's rule describes mathematically whether or not a gene for altruistic behavior will spread in a population:


title: Evolutionary psychology

text: The concept serves to explain how natural selection can perpetuate altruism. If there is an "altruism gene" (or complex of genes) that influences an organism's behavior to be helpful and protective of relatives and their offspring, this behavior also increases the proportion of the altruism gene in the population, because relatives are likely to share genes with the altruist due to common descent. Altruists may also have some way to recognize altruistic behavior in unrelated individuals and be inclined to support them. As Dawkins points out in "The Selfish Gene" (Chapter 6) and "The Extended Phenotype", this must be distinguished from the green-beard effect.


title: Evolutionary psychology

text: Although it is generally true that humans tend to be more altruistic toward their kin than toward non-kin, the relevant proximate mechanisms that mediate this cooperation have been debated (see kin recognition), with some arguing that kin status is determined primarily via social and cultural factors (such as co-residence, maternal association of sibs, etc.), while others have argued that kin recognition can also be mediated by biological factors such as facial resemblance and immunogenetic similarity of the major histocompatibility complex (MHC). For a discussion of the interaction of these social and biological kin recognition factors see Lieberman, Tooby, and Cosmides (2007) (PDF).


title: Evolutionary psychology

text: Whatever the proximate mechanisms of kin recognition there is substantial evidence that humans act generally more altruistically to close genetic kin compared to genetic non-kin.


title: Evolutionary psychology

text: Although interactions with non-kin are generally less altruistic compared to those with kin, cooperation can be maintained with non-kin via mutually beneficial reciprocity as was proposed by Robert Trivers. If there are repeated encounters between the same two players in an evolutionary game in which each of them can choose either to "cooperate" or "defect," then a strategy of mutual cooperation may be favored even if it pays each player, in the short term, to defect when the other cooperates. Direct reciprocity can lead to the evolution of cooperation only if the probability, w, of another encounter between the same two individuals exceeds the cost-to-benefit ratio of the altruistic act:


title: Evolutionary psychology

text: Reciprocity can also be indirect if information about previous interactions is shared. Reputation allows evolution of cooperation by indirect reciprocity. Natural selection favors strategies that base the decision to help on the reputation of the recipient: studies show that people who are more helpful are more likely to receive help. The calculations of indirect reciprocity are complicated and only a tiny fraction of this universe has been uncovered, but again a simple rule has emerged. Indirect reciprocity can only promote cooperation if the probability, q, of knowing someone's reputation exceeds the cost-to-benefit ratio of the altruistic act:


title: Evolutionary psychology

text: One important problem with this explanation is that individuals may be able to evolve the capacity to obscure their reputation, reducing the probability, q, that it will be known.


title: Evolutionary psychology

text: Trivers argues that friendship and various social emotions evolved in order to manage reciprocity. Liking and disliking, he says, evolved to help present-day humans' ancestors form coalitions with others who reciprocated and to exclude those who did not reciprocate. Moral indignation may have evolved to prevent one's altruism from being exploited by cheaters, and gratitude may have motivated present-day humans' ancestors to reciprocate appropriately after benefiting from others' altruism. Likewise, present-day humans feel guilty when they fail to reciprocate. These social motivations match what evolutionary psychologists expect to see in adaptations that evolved to maximize the benefits and minimize the drawbacks of reciprocity.


title: Evolutionary psychology

text: Evolutionary psychologists say that humans have psychological adaptations that evolved specifically to help us identify nonreciprocators, commonly referred to as "cheaters." In 1993, Robert Frank and his associates found that participants in a prisoner's dilemma scenario were often able to predict whether their partners would "cheat," based on a half-hour of unstructured social interaction. In a 1996 experiment, for example, Linda Mealey and her colleagues found that people were better at remembering the faces of people when those faces were associated with stories about those individuals cheating (such as embezzling money from a church).


title: Evolutionary psychology

text: Humans may have an evolved set of psychological adaptations that predispose them to be more cooperative than otherwise would be expected with members of their tribal in-group, and, more nasty to members of tribal out groups. These adaptations may have been a consequence of tribal warfare. Humans may also have predispositions for "altruistic punishment" – to punish in-group members who violate in-group rules, even when this altruistic behavior cannot be justified in terms of helping those you are related to (kin selection), cooperating with those who you will interact with again (direct reciprocity), or cooperating to better your reputation with others (indirect reciprocity).


title: Evolutionary psychology

text: Though evolutionary psychology has traditionally focused on individual-level behaviors, determined by species-typical psychological adaptations, considerable work has been done on how these adaptations shape and, ultimately govern, culture (Tooby and Cosmides, 1989). Tooby and Cosmides (1989) argued that the mind consists of many domain-specific psychological adaptations, some of which may constrain what cultural material is learned or taught. As opposed to a domain-general cultural acquisition program, where an individual passively receives culturally-transmitted material from the group, Tooby and Cosmides (1989), among others, argue that: "the psyche evolved to generate adaptive rather than repetitive behavior, and hence critically analyzes the behavior of those surrounding it in highly structured and patterned ways, to be used as a rich (but by no means the only) source of information out of which to construct a 'private culture' or individually tailored adaptive system; in consequence, this system may or may not mirror the behavior of others in any given respect." (Tooby and Cosmides 1989).


title: Evolutionary psychology

text: Biological explanations of human culture also brought criticism to evolutionary psychology: Evolutionary psychologists see the human psyche and physiology as a genetic product and assume that genes contain the information for the development and control of the organism and that this information is transmitted from one generation to the next via genes. Evolutionary psychologists thereby see physical and psychological characteristics of humans as genetically programmed. Even then, when evolutionary psychologists acknowledge the influence of the environment on human development, they understand the environment only as an activator or trigger for the programmed developmental instructions encoded in genes. Evolutionary psychologists, for example, believe that the human brain is made up of innate modules, each of which is specialised only for very specific tasks, e. g. an anxiety module. According to evolutionary psychologists, these modules are given before the organism actually develops and are then activated by some environmental event. Critics object that this view is reductionist and that cognitive specialisation only comes about through the interaction of humans with their real environment, rather than the environment of distant ancestors. Interdisciplinary approaches are increasingly striving to mediate between these opposing points of view and to highlight that biological and cultural causes need not be antithetical in explaining human behaviour and even complex cultural achievements.


title: Evolutionary psychology

text: According to Paul Baltes, the benefits granted by evolutionary selection decrease with age. Natural selection has not eliminated many harmful conditions and nonadaptive characteristics that appear among older adults, such as Alzheimer disease. If it were a disease that killed 20-year-olds instead of 70-year-olds this may have been a disease that natural selection could have eliminated ages ago. Thus, unaided by evolutionary pressures against nonadaptive conditions, modern humans suffer the aches, pains, and infirmities of aging and as the benefits of evolutionary selection decrease with age, the need for modern technological mediums against non-adaptive conditions increases.


title: Evolutionary psychology

text: As humans are a highly social species, there are many adaptive problems associated with navigating the social world (e.g., maintaining allies, managing status hierarchies, interacting with outgroup members, coordinating social activities, collective decision-making). Researchers in the emerging field of evolutionary social psychology have made many discoveries pertaining to topics traditionally studied by social psychologists, including person perception, social cognition, attitudes, altruism, emotions, group dynamics, leadership, motivation, prejudice, intergroup relations, and cross-cultural differences.


title: Evolutionary psychology

text: When endeavouring to solve a problem humans at an early age show determination while chimpanzees have no comparable facial expression. Researchers suspect the human determined expression evolved because when a human is determinedly working on a problem other people will frequently help.


title: Evolutionary psychology

text: Adaptationist hypotheses regarding the etiology of psychological disorders are often based on analogies between physiological and psychological dysfunctions, as noted in the table below. Prominent theorists and evolutionary psychiatrists include Michael T. McGuire, Anthony Stevens, and Randolph M. Nesse. They, and others, suggest that mental disorders are due to the interactive effects of both nature and nurture, and often have multiple contributing causes.


title: Evolutionary psychology

text: Evolutionary psychologists have suggested that schizophrenia and bipolar disorder may reflect a side-effect of genes with fitness benefits, such as increased creativity. (Some individuals with bipolar disorder are especially creative during their manic phases and the close relatives of people with schizophrenia have been found to be more likely to have creative professions.) A 1994 report by the American Psychiatry Association found that people with schizophrenia at roughly the same rate in Western and non-Western cultures, and in industrialized and pastoral societies, suggesting that schizophrenia is not a disease of civilization nor an arbitrary social invention. Sociopathy may represent an evolutionarily stable strategy, by which a small number of people who cheat on social contracts benefit in a society consisting mostly of non-sociopaths. Mild depression may be an adaptive response to withdraw from, and re-evaluate, situations that have led to disadvantageous outcomes (the "analytical rumination hypothesis") (see Evolutionary approaches to depression).


title: Evolutionary psychology

text: Some of these speculations have yet to be developed into fully testable hypotheses, and a great deal of research is required to confirm their validity.


title: Evolutionary psychology

text: Evolutionary psychology has been applied to explain criminal or otherwise immoral behavior as being adaptive or related to adaptive behaviors. Males are generally more aggressive than females, who are more selective of their partners because of the far greater effort they have to contribute to pregnancy and child-rearing. Males being more aggressive is hypothesized to stem from the more intense reproductive competition faced by them. Males of low status may be especially vulnerable to being childless. It may have been evolutionary advantageous to engage in highly risky and violently aggressive behavior to increase their status and therefore reproductive success. This may explain why males are generally involved in more crimes, and why low status and being unmarried are associated with criminality. Furthermore, competition over females is argued to have been particularly intensive in late adolescence and young adulthood, which is theorized to explain why crime rates are particularly high during this period. Some sociologists have underlined differential exposure to androgens as the cause of these behaviors, notably Lee Ellis in his evolutionary neuroandrogenic (ENA) theory.


title: Evolutionary psychology

text: Many conflicts that result in harm and death involve status, reputation, and seemingly trivial insults. Steven Pinker in his book "The Blank Slate" argues that in non-state societies without a police it was very important to have a credible deterrence against aggression. Therefore, it was important to be perceived as having a credible reputation for retaliation, resulting in humans developing instincts for revenge as well as for protecting reputation ("honor"). Pinker argues that the development of the state and the police have dramatically reduced the level of violence compared to the ancestral environment. Whenever the state breaks down, which can be very locally such as in poor areas of a city, humans again organize in groups for protection and aggression and concepts such as violent revenge and protecting honor again become extremely important.


title: Evolutionary psychology

text: Rape is theorized to be a reproductive strategy that facilitates the propagation of the rapist's progeny. Such a strategy may be adopted by men who otherwise are unlikely to be appealing to women and therefore cannot form legitimate relationships, or by high-status men on socially vulnerable women who are unlikely to retaliate to increase their reproductive success even further. The sociobiological theories of rape are highly controversial, as traditional theories typically do not consider rape to be a behavioral adaptation, and objections to this theory are made on ethical, religious, political, as well as scientific grounds.


title: Evolutionary psychology

text: Adaptationist perspectives on religious belief suggest that, like all behavior, religious behaviors are a product of the human brain. As with all other organ functions, cognition's functional structure has been argued to have a genetic foundation, and is therefore subject to the effects of natural selection and sexual selection. Like other organs and tissues, this functional structure should be universally shared amongst humans and should have solved important problems of survival and reproduction in ancestral environments. However, evolutionary psychologists remain divided on whether religious belief is more likely a consequence of evolved psychological adaptations, or a byproduct of other cognitive adaptations.


title: Evolutionary psychology

text: Coalitional psychology is an approach to explain political behaviors between different coalitions and the conditionality of these behaviors in evolutionary psychological perspective. This approach assumes that since human beings appeared on the earth, they have evolved to live in groups instead of living as individuals to achieve benefits such as more mating opportunities and increased status. Human beings thus naturally think and act in a way that manages and negotiates group dynamics.


title: Evolutionary psychology

text: Coalitional psychology offers falsifiable ex ante prediction by positing five hypotheses on how these psychological adaptations operate:


title: Evolutionary psychology

text: Critics of evolutionary psychology accuse it of promoting genetic determinism, panadaptationism (the idea that all behaviors and anatomical features are adaptations), unfalsifiable hypotheses, distal or ultimate explanations of behavior when proximate explanations are superior, and malevolent political or moral ideas.


title: Evolutionary psychology

text: Critics have argued that evolutionary psychology might be used to justify existing social hierarchies and reactionary policies. It has also been suggested by critics that evolutionary psychologists' theories and interpretations of empirical data rely heavily on ideological assumptions about race and gender.


title: Evolutionary psychology

text: In response to such criticism, evolutionary psychologists often caution against committing the naturalistic fallacy – the assumption that "what is natural" is necessarily a moral good. However, their caution against committing the naturalistic fallacy has been criticized as means to stifle legitimate ethical discussions.