Extended Data Figure 9: Pigmentation is oligogenic but selection on it was polygenic.

Selection coefficient ($\mathrm{s}$) and effect size ($\mathrm{\beta }$) from the pan-UKBB skin color phenotype for 110 independent SNPs passing the GWAS P-value threshold of p<5×10⁻⁸. Following ⁵⁷, the orange line is a linear regression on all SNPs (99 blue and 11 orange markers), while the blue line includes only SNPs with $\left|\mathrm{\beta }\right|<0.05$ (99 blue markers). Although the correlation appears different (with the difference between Fisher Z-transformed Pearson r showing a P-value of 0.001), the slopes are not significantly different (P = 0.10), consistent with a model in which selection for pigmentation had an equal impact on all variants in proportion to effect size.