Biology and culture in recent selection

This isn’t a long essay; just a pointer to a Nature feature by Erika Check Hayden where I make an appearance to represent the anthropological viewpoint on recent genetic changes:

[C]urrent human populations are much more genetically diverse than this hypothesis predicts, so Moyzis and Hawks have concluded that evolution must have ramped up over the past 40,000 years. They chalk some of this acceleration up to human population growth, which exposed the species to more new mutations and created more raw material for selection. But the other reason, Hawks thinks, is culture because although the physiology of humans has not changed much in the past 40,000 years, their expansion and migration means that lifestyles, languages and technologies certainly have.
Although not everyone agrees with Hawks's claims, the best understood example of recent human evolution does seem to fit. Genetic mutations that allow adults to digest lactose, a sugar found in milk, have emerged independently in different populations in response to the same cultural innovation cattle domestication. "I don't see culture as an alternative to genetics, I see culture as being the explanatory factor for these genetic changes," says Hawks. "There is no explanation for change without the gene-environment interaction."

Well, there’s my Michigan training.

Others have sometimes had the view that culture should replace genetic change in recent human history. I think that’s wrong. Culture constrains genetic changes. Some kinds of cultural evolution can fall into relatively stable patterns that allow longer-term genetic changes to happen – like the sustained subsistence changes brought on by agriculture. Those are great targets for adaptive genetic changes, and they might even generate circumstances that enable further cultural changes. That’s a true biocultural evolutionary feedback.

Other cultural systems continue to fluctuate more rapidly. But this is nothing new – many environmental changes fluctuate on a time scale too rapid for genetic changes to catch up. Even so, sometimes genetic polymorphisms occur as equilibrium solutions to such rapidly fluctuating systems. In any event, we can address these questions quantitatively.

The article contains a mix of stuff about human behavioral evolution – ranging from recurrently selected genes in hominids up to our stuff on very recent evolution. Oh, and there’s this:

Preuss says that such precise dissections of human-specific traits are still quite rare. "If you go beyond the bland expression of 'advanced cognition' and try to talk about cognitive mechanisms and abilities, we don't really know that much," he says. This means that there is a glut of genomic data but a paucity of crucial information from other fields that would help to make sense of it. "We need to start connecting this genetic world to the traditional anthropological approaches," agrees Hawks, who sees genomics as an inspiration to start collecting and sharing data on an equivalent scale in his own discipline.

That’s a point I’ve made several times here, and I’m glad to see it coming out in my interviews elsewhere. We know so much now about the human genome, but we know yet more about the archaeological, linguistic and biological record of the last 20,000 years. It’s not so easy to get all these data together. But there’s huge potential here.

References:

Hayden EC. 2009. Darwin 200: The other strand. Nature 457:776-779. doi:10.1038/457776a