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. 2009 Mar 7;276(1658):809-14.
doi: 10.1098/rspb.2008.1563.

Distance from Africa, not climate, explains within-population phenotypic diversity in humans

Lia Betti  1 , François Balloux, William Amos, Tsunehiko Hanihara, Andrea Manica
Affiliations

Distance from Africa, not climate, explains within-population phenotypic diversity in humans

Lia Betti et al. Proc Biol Sci. .

Abstract

The relative importance of ancient demography and climate in determining worldwide patterns of human within-population phenotypic diversity is still open to debate. Several morphometric traits have been argued to be under selection by climatic factors, but it is unclear whether climate affects the global decline in morphological diversity with increasing geographical distance from sub-Saharan Africa. Using a large database of male and female skull measurements, we apply an explicit framework to quantify the relative role of climate and distance from Africa. We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity, while climate plays no role. By selecting the most informative set of traits, it was possible to explain over half of the worldwide variation in phenotypic diversity. These results mirror those previously obtained for genetic markers and show that 'bones and molecules' are in perfect agreement for humans.

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Figures

Figure 1
Figure 1
Plot of within-population phenotypic variance versus geographical distance from the best centre of origin for (a) males and (b) females. The solid line refers to the best fit for the complete dataset while the dotted line refers to the dataset without outlier populations. Populations are represented by circles, with outliers highlighted by a filled circle.
Figure 2
Figure 2
Maps showing the likely area of origin of the out-of-Africa expansion for (a) the full male dataset, (b) the male dataset excluding the two outlier populations from Patagonia, (c) the full female dataset and (d) the female dataset excluding the outlier population from Kenya. Lighter colours represent better fits of the models to the data, and the area containing the most likely centre of origin is highlighted by a green line. The Americas (not displayed) did not contain any likely origin. The areas not investigated as possible origins are shown in grey.
Figure 3
Figure 3
Location of (a,c,e) highly informative traits in red and (b,d,f) less informative traits in green.
Figure 4
Figure 4
Plot of within-population phenotypic variance versus geographical distance from the best centre of origin, for (a) males and (b) females. The phenotypic variance is calculated over the best combination of traits defined in males. The solid line refers to the best fit for the complete dataset while the dotted line refers to the dataset without outlier populations, which are highlighted by filled circles.
See this image and copyright information in PMC

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