Joined: 07 Feb 2007 {Posts: 1770 } Location: Lookin DC Metro, Feelin Geneva
Posted: Tue 07 Jul 2009 14:15 Post subject: Drift not selection most reponsible for skull shape
Quote:
Drift more important than selection in shaping the human skull
This is in agreement with von Cramon-Taubadel (2009) who found congruence between human neutral genetic variation and skull morphology, and with Baab et al. who found no evidence for the influence of climate in shaping human cranial robusticity.
American Journal of Physical Anthropology doi:10.1002/ajpa.21115
The relative role of drift and selection in shaping the human skull
Lia Betti et al.
Abstract
Human populations across the world vary greatly in cranial morphology. It is highly debated to what extent this variability has accumulated through neutral processes (genetic drift) or through natural selection driven by climate. By taking advantage of recent work showing that geographic distance along landmasses is an excellent proxy for neutral genetic differentiation, we quantify the relative role of drift versus selection in an exceptionally large dataset of human skulls. We show that neutral processes have been much more important than climate in shaping the human cranium. We further demonstrate that a large proportion of the signal for natural selection comes from populations from extremely cold regions. More generally, we show that, if drift is not explicitly accounted for, the effect of natural selection can be greatly overestimated.
As long ago as 1911, Franz Boas published voluminous data that the U.S.-born children of immigrants have different skull shapes from their parents (as well as being taller, heavier, healthier, etc.). He was ignored in this as he was in much of what he uncovered.
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