1Departments of Anthropology and Biology, Pennsylvania State University, 2DFG Center for Advanced Studies “Words, Bones, Genes, Tools”, University of Tübingen, 3Research Centre in Evolutionary Anthropology and Palaeoecology, Liverpool John Moores University
March 28, 2019 3:15, CC Room 26 C
It has been hypothesized that human body size sexual dimorphism was reduced via positive selection following the transition from hunting and gathering to agriculture due to a more equal division of labor, shifts in technology, and/or nutritional changes. Alternatively, any recent changes in the degree of human sexual dimorphism could instead reflect genetic drift. Here we apply a genome wide association study (GWAS) approach to study the recent evolutionary history of sexual dimorphism in human body size phenotypes. GWAS can identify genetic loci associated with phenotypic variation; the identified variants can then be analyzed to infer recent evolutionary histories of the corresponding traits. Using GWAS data from the UKBiobank, we identified 147 single nucleotide polymorphisms that are both significantly associated with height variation in either males or females or in both sexes (P<1x10-13) and have a significant sex difference for height (P<0.0001). Using the singleton density score statistic, which quantifies recent changes in the frequencies of alleles underlying polygenic traits, we observed evidence of recent (within ~3,000yr) positive selection (P<0.0001) at these loci, specifically on alleles associated with less sexual dimorphism. This effect was predominantly driven by increases in the frequencies of alleles associated with shorter male stature. In stark contrast, for loci associated with height but not sexual dimorphism there is evidence of recent positive selection on alleles associated with taller height. Our results support the hypothesis of recent positive selection for reduced human body size sexual dimorphism and demonstrate the value of GWAS approaches for testing anthropological hypotheses.
The Penn State University Erickson Discovery, Presidential Leadership Academy Enrichment, and Liberal Arts Enrichment Grants (all to A.M.A); NIH grant R01-GM115656 (to G.P); and DFG grant FOR-2237.