Paternal genetic structure of Hainan Islanders

Hainan Island on Wikipedia.

PLoS ONE. 2008 May 14;3(5):e2168.

Paternal genetic structure of Hainan aborigines isolated at the entrance to East Asia.

Li D, Li H, Ou C, Lu Y, Sun Y, Yang B, Qin Z, Zhou Z, Li S, Jin L.

BACKGROUND: At the southern entrance to East Asia, early population migration has affected most of the Y-chromosome variations of East Asians. METHODOLOGY/PRINCIPAL FINDINGS: To assess the isolated genetic structure of Hainan Island and the original genetic structure at the southern entrance, we studied the Y chromosome diversity of 405 Hainan Island aborigines from all the six populations, who have little influence of the recent mainland population relocations and admixtures. Here we report that haplogroups O1a* and O2a* are dominant among Hainan aborigines. In addition, the frequency of the mainland dominant haplogroup O3 is quite low among these aborigines, indicating that they have lived rather isolated. Clustering analyses suggests that the Hainan aborigines have been segregated since about 20 thousand years ago, after two dominant haplogroups entered East Asia (31 to 36 thousand years ago). CONCLUSIONS/SIGNIFICANCE: Our results suggest that Hainan aborigines have been isolated at the entrance to East Asia for about 20 thousand years, whose distinctive genetic characteristics could be used as important controls in many population genetic studies.

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Sexual dimorphism in 26 populations

Using the same data as before, I calculate the sexual dimorphism in 26 craniometric samples from around the world.

There are many ways to express sexual dimorphism, i.e., differences between men and women, which extend to both size and shape. I will limit myself to the simple measure of the average (over all traits) ratio of the male to the female mean (over all individuals).

Zulu 1.06
Egypt 1.06
Atayal 1.06
Zalavar 1.06
San 1.07
Hainan 1.07
Tasmanian 1.07
Moriori 1.07
Norse 1.07
Lake Alexandrina 1.07
Tolai 1.07
Dogon 1.08
Berg 1.08
Philippine 1.08
Yauyos 1.08
Teita 1.08
Buriat 1.08
Santa Cruz Island 1.08
North Kyushu 1.08
Ainu 1.09
Andaman Islands 1.09
Arikara 1.09
Hokkaido 1.09
Mokapu 1.09
Easter Island 1.09
Guam 1.09

So, it appears that these populations do not differ by much from each other in terms of sexual dimorphism. But, if we look at individual traits, the situation is much different. Men and women are most dimorphic (in decreasing order) in terms of their glabella projection (1.52), supraorbital projection (1.25), simotic subtense (1.2), mastoid breadth (1.18), mastoid height (1.16). So, it turns out that men and women can be quite different in terms of some traits, but not in terms of others.

Who is the most diverse of them all?

Here is the diversity ranking of Howells' 28 human populations based on 45 cranial measurements. The numbers are the average population standard deviation (for each population over all 45 measurements) as a percentage of the average human standard deviation (for all groups over all 45 measurements). In parentheses, the racial cluster of each population according to my previous analysis.

Guam 76.8 (Mongoloid)
Andaman Islands 76.8 (Andamanese)
Santa Cruz Island 76.9 (Americanoid)
Zalavar 77.0 (Caucasoid)
Yauyos 77.8 (Americanoid)
Easter Island 77.9 (Polynesoid)
Arikara 78.2 (Americanoid)
Moriori 78.2 (Polynesoid)
Tolai 78.3 (Australoid)
Lake Alexandrina 78.3 (Australoid)
Atayal 78.8 (Mongoloid)
Hainan 79.2 (Mongoloid)
Anyang 79.9 (Mongoloid)
Norse 80.1 (Caucasoid)
North Kyushu 80.6 (Mongoloid)
Mokapu 80.9 (Polynesoid)
Ainu 81.3 (Ainu)
Eskimo 81.6 (Eskimo)
Egypt 82.8 (Caucasoid)
Phillipine 84.2 (Mongoloid)
Dogon 84.5 (Negroid)
Teita 84.8 (Negroid)
Zulu 85.1 (Negroid)
Berg 85.3 (Caucasoid)
Tasmanian 85.3 (Australoid)
Hokkaido 85.5 (Mongoloid)
Buriat 87.0 (Mongoloid)
San 89.0 (Capoid)