On this episode of Unsupervised Learning, Razib talks to Davide Piffer, whose Substack examines genetic differences between populations. Piffer has been publishing on human genetic variation for a decade, and recently started a Substack, Piffer Pilfer, exploring similar issues in detail over a series of posts.

Razib asks Piffer about the difficulties in analyzing polygenic scores from quantitative traits in ancient DNA samples. How does he do in technical terms, from genome quality to imputation to ancient populations from modern ones? Then, they discuss some of Piffer's findings, in particular, his work on pigmentation. Piffer talks about how he discovered that modern European pigmentation, and in particular, light complexion, is the product of both admixture from different populations with different characteristics and natural selection over the millennia. Piffer talks about how he discovered that selection for lighter pigmentation continued into the Iron Age.