The relative role of drift and selection in shaping the human skull.
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.
Betti
Lia
L
Evolutionary Ecology Group, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
Balloux
François
F
Hanihara
Tsunehiko
T
Manica
Andrea
A
D005075:Biological Evolution; D049628:Body Size; D002980:Climate; D005260:Female; D005580:Fossils; D040961:Genetic Drift; D005843:Geography; D006801:Humans; D016014:Linear Models; D008297:Male; D010641:Phenotype; D012641:Selection, Genetic; D012886:Skull / Q000033:anatomy & histology*