Random genetic drift, natural selection, and noise in human cranial evolution

Area of Science:

• Human evolution
• Population genomics
• Cranial morphology

Background:

• Comparative studies of human cranial variation face challenges due to group relationships and departures from neutral evolutionary models.
• Reconstructing population relationships using cranial morphology can be hindered by evolutionary complexities.

Purpose of the Study:

• To assess how group relationships complicate comparative adaptation studies in human cranial variation.
• To determine if deviations from neutral additive models hinder population relationship reconstruction using cranial morphology.

Main Methods:

• Utilized a maximum likelihood evolutionary model fitting approach.
• Employed a mixed dataset combining population genomic and cranial data.
• Evaluated and compared the goodness of fit for various human cranial evolution models, including those constrained by genomic variation.

Main Results:

• Population genomics models significantly outperform traditional comparative human biology models in fitting cranial variation.
• Cranial morphology contains limited information for reconstructing recent human evolution but strongly influences comparative adaptation studies.
• Deviations from neutral drift models indicate the influence of environmental effects, gene flow, and natural selection on human cranial variation, with a notable signal in a Siberian group.

Conclusions:

• Human cranial evolution is intricate, driven by multiple interacting processes rather than a single dominant one.
• Integrating phenomic, genomic, and environmental data offers a more comprehensive understanding of human cranial evolution.
• Future research should adopt a holistic approach to unravel the complexities of human cranial variation.