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Recently, Joseph Henrich of UBC has been promoting his cultural brain hypothesis. The goal is to explain a selection pressure behind the development of the human brain and general intelligence. The basic premise is that our brains evolved to be better and better at accurately replicating cultural information (or memes) between generations. A secondary part of his hypothesis is that there was a tight co-evolution between culture and the genes that shape us.

This seems contrary to the more orthodox thinking of that genes shaped the base of humans largely without large-scale culture (when we were small hunter-gatherer tribes and thus culture was minimal), and then recently (on an evolutionary time scale) large-scale culture 'turned on' and there has not been a sufficient time for this to produce large genetic differences. In simplest terms, the co-evolution was minimal and instead we should think of the key players being gene evolution followed by cultural evolution (on different timescales).

To confuse things further, some scientists (like Satoshi Kanazawa of LSE) view most of what we associated with the 'perks' of human brain (such as general intelligence) as mal-adaptive on the individual level. Thus there seems to be a large distinction between the 3 general threads, which raises the question:

What is the key evidence for the cultural brain hypothesis and gene-culture co-evolution?

The only evidence I know of potential recent co-evolution of culture and genes is Dediu & Ladd's (2007) suggestion that the split between tonal and atonal languages is related to a recent (~6k years ago) mutation in the ASPM gene. Is there other evidence of recent co-evolution between genes and large-scale culture?

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