My recent focus on the lack of genetic continuity between
hunter-gatherer and farming populations genetically and
culturally is primarily due to the fact that we’re not in
theory-land; the extraction of ancient DNA samples is steady-as-
it-goes and is sharpening and overturning our understanding of
the past. The relationship between culture and genetics is of
particular importance in this case, genes serve not only as
markers which we can track population movements, but genes
themselves are embedded in dynamics which need not be connected
to population movements. Consider lactase persistence, which
confers the ability to digest milk as an adult. In the 20th
century “lactose intolerance” was assumed to be a pathology, but
it turns out that most human populations can not digest milk
sugar as adults due to the lack of production of the lactase
enzyme. This is the ancestral type. Rather, different mutations
which result in the persistence of lactase production into
adulthood seem to have arisen independently in se