Dental morphological evidence for European admixture in Mongolia and western China

Lee, C. and Scott, G. R. (2011), Brief communication: Two-rooted lower Canines—A European trait and sensitive indicator of admixture across Eurasia. American Journal of Physical Anthropology, 146: 481–485. doi: 10.1002/ajpa.21585
With the exception of Carabelli's trait, the European dentition is better known for the morphological traits that it does not exhibit rather than the ones that it does. One root trait, however, runs counter to the characterization of reduced and simplified European crowns and roots. Although a rare trait in general, two-rooted lower canines are much more common in Europeans than in any other regional grouping and, given adequate sample sizes, can be useful in evaluating gene flow between Europeans and neighboring groups. In European samples, two-rooted lower canines consistently exhibit frequencies of 5–8%. In our sample from northern Spain, the trait attains a frequency of almost 10%. In contrast, in Sub-Saharan Africans the trait is virtually unknown while in Asian and Asian-derived populations, it varies between 0.0 and 1.0%. Here we show that two-rooted canine frequencies for new migrants along the western frontiers of China and Mongolia ranged from 0–4%. These data suggest European-derived populations migrated into western China (Xinjiang Province) and Mongolia (Bayan Olgii Aimag) sometime during the late Bronze age (1000–400 BCE). [. . .]

One of the major concerns of Alexandersen (1963) regarding two-rooted lower canines revolved around the issue of ‘‘atavism.’’ This term, rarely used today, begs the question of whether or not this double rooted form was common at one time, then disappeared, only to reappear sometime later. Swindler (1995) notes that ‘‘the deciduous and permanent canines in the majority of living primates have a single root.’’ This suggests that two-rooted lower canines are not the ancestral condition in anthropoids or hominoids. Rather, the phenotype is a derived condition, found primarily in recent human populations distributed across Western Eurasia.


The appearance of a new population on the western frontier also supports the findings of previous research in cranial metrics, dental nonmetrics, and DNA. Using cranial metrics and archaeological dating, Han (1994) hypothesized the earliest large-scale migration into western China occurred during the early Bronze age (2000 BCE) from Central Asia or southern Siberia. Dental nonmetric data also support multiple migrations into western China (Xinjiang Province) from Central Asia during the Bronze age to Iron age (Lee, 2007; Zhang, 2010). mtDNA studies on archaeological and modern population samples from Xinjiang Province show heterogeneous Asian and European genetic signatures dating from the Bronze age to the present (Yao et al., 2004; Cui et al., 2010; Zhang et al., 2010; Li et al., 2010).

As the frequency of two-rooted canines is highest in European samples and low to nonexistent in Asians, we propose this trait was introduced into East Asia by Indo- European speaking groups or their affines crossing the western frontier of China and Mongolia. Further data are needed to clarify aspects of these population movements, including the identity of the migrants, along with the number, routes, and timing of the migrations.

Although two-rooted lower canines cannot offer the precision of DNA in evaluating the ancestry in individual skulls, this trait is a sensitive indicator of admixture wherever Europeans come in contact with Asian or African populations. As this distinctive trait can be scored with relative ease in large samples, it provides a useful supplemental tool in discerning gene flow between distantly related populations going back many millennia.

Daniel MacArthur twitter commentary from CSHL Personal Genomes meeting

This meeting took place a couple weeks ago -- dgmacarthur is presently posting from ICHG2011.

James Watson is asking a question. At least I think it's a question. #cshlpg
Yes, it was a question: hasn't ELSI just been a huge waste of money? Wait, no - he's back to talking again. #cshlpg

Manfred Kayser is talking about the genetics of human appearance, but his talk is untweetable. #cshlpg
Although Kayser's talk is untweetable it sounds as though a lot of this is close to publication - so stay tuned. #cshlpg

JV [Joris Veltman] discussing published analysis of de novo variants in mental retardation: #cshlpg
JV: total number of de novo coding mutations is not higher in MR patients - but more likely to be in brain genes. #cshlpg

What fraction of the human genome is functional?

What fraction of the human genome is functional?

Chris P. Ponting1,3 and Ross C. Hardison2,3


Many evolutionary studies over the past decade have estimated ?sel, the proportion of all nucleotides in the human genome that are subject to purifying selection because of their biological function. Most of these studies have estimated the nucleotide substitution rates from genome sequence alignments across many diverse mammals. Some ?sel estimates will be affected by the heterogeneity of substitution rates in neutral sequence across the genome. Most will also be inaccurate if change in the functional sequence repertoire occurs rapidly relative to the separation of lineages that are being compared. Evidence gathered from both evolutionary and experimental analyses now indicate that rates of “turnover” of functional, predominantly noncoding, sequence are, indeed, high. They are sufficiently high that an estimated 50% of mouse constrained noncoding sequence is predicted not to be shared with rat, a closely related rodent. The rapidity of turnover results in, at least, a twofold underestimate of ?sel by analyses that measure constraint across the eutherian phylogeny. Approaches that take account of turnover estimate that the steady-state value of ?sel lies between 10% and 15%. Experimental studies corroborate the predicted rates of loss and gain of noncoding functional sites. These studies show the limitations inherent in the use of deep sequence conservation for identifying functional sequence. Experimental investigations focusing on lineage-specific, noncoding, and functional sequence are now essential if we are to appreciate the complete functional repertoire of the human genome.

More excerpts from Chris Stringer's "The Origin of Our Species"


On group selection:

On modern behavior:



On genetic evidence for archaic admixture:


On Iwo Eleru:


Possible reason we don't have pigmentation genes from Neanderthals:

Out of Eurasia

From Chris Stringer's most recent book ("The Origin of Our Species"):
And the evidence from Dmanisi is now being added to this rethink, since the lack of very ancient fossil human evidence from Asia, apart from Dmanisi, is considered by archaeologists like Robin Dennell and Wil Roebroeks to reflect a lack of preservation and discovery, rather than a real absence. Combining the primitiveness of the Dmanisi specimens and tools with a similar view of the Liang Bua finds, it is argued that there was a widespread phase of human evolution in Eurasia about 2 million years ago, which is now only represented by the isolated Dmanisi and "Hobbit" fossils. This alternative scenario has a small-brained and small-bodied pre-erectus species, perhaps comparable to Homo habilis or even a late australopithecine, dispersing from Africa with primitive tools over 2 million years ago, reaching the Far East and, eventually, Flores. In Asia, this ancestral species then gave rise to the Dmanisi people and Homo erectus, while Dmanisi-like people reentered Africa about 1.8 million years ago, and evolved into later populations there -- including, eventually, Homo sapiens. So the orthodoxy of Out of Africa 1 is being challenged because of new evidence, and new interpretations of old evidence.'s "Human Genetic Diversity Project" will apparently be offering autosomal DNA testing soon. They just gave away 2000 free "upgrades" to people who had previously done Y or mtDNA tests through Ancestry DNA, evidently for a forthcoming service along the lines of 23andMe's Relative Finder.
What You'll Get
Your Genetic Ethnicity
More comprehensive DNA matching
1. What is the research project?


2. What information will be collected?




3. How will the information be used?


Previously, have advertised for a PhD population geneticist: