Evolutionary genomic patterns of recent natural selection on body size sex differences in humans
Open Access
- Author:
- Arner, Audrey
- Area of Honors:
- Biological Anthropolgy
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- George H Perry, Thesis Supervisor
Douglas Warren Bird, Thesis Honors Advisor - Keywords:
- GWAS
UK Biobank
natural selection
height
sexual dimorphism - Abstract:
- Levels of sex differences for quantitative human body size and shape phenotypes are hypothesized to have been reduced following the agricultural transition in an evolutionary response to relatively more equal divisions of labor and shifts in technology. Here we apply a multi-step approach to study the recent evolutionary history of the following human sexually differentiated phenotypes: height, body mass, hip circumference, body fat percentage, and waist circumference. We first analyzed genome wide association study (GWAS) results for UK Biobank individuals (~167,000 males and ~197,000 females) to identify a total of 119,023 single nucleotide polymorphisms (SNPs) significantly associated with at least one of our phenotypes in either males or females or in both sexes (P<5x10-8). From the set of phenotype-associated loci we identified 3,016 SNPs (2.5%) with significant differences (False-discovery rate < 0.001) in the strength of association between the male and female-specific GWAS results (n=3,016 SNPs after pruning for linkage disequilibrium). We identified signatures of recent positive selection on our set of SNPs associated with sex differences using the singleton density score statistic. This effect was predominantly driven by significant increases in the frequencies of alleles associated with greater body fat percentage in females (permutation test; P = 0.0028) and greater hip circumference in males (P = 0.0467). Our study helps demonstrate the value of GWAS for testing anthropological hypotheses; our results are at least partly opposite to expectations based on longstanding hypotheses concerning the direction of recent evolutionary change in human body size and shape sex differences.