Thanks for the links Mike!

Thanks for the comment, Mike. Yes, “dual inheritance” theory (DIT) is largely ignored by Diamond in this book. I would maintain, however, that cultural evolution is a proximate factor built upon environmental attributes and, once populations capitalize on those attributes, cultural evolution from dual inheritance takes over, contributing to the diversity of culture we observe. It would seem that most DI theorists concede this idea, with the classic example that once an agrarian lifestyle is established within a culture, human physiology adapts via selection to digest the compounds and nutrients native to that lifestyle. Again, this co-dependency intensifies AFTER the lifestyle shifts from environmental influences (ultimate cause) occur.

And there is no debate that once modern societies took shape, cultural evolution quickly outpaced biological evolution. That is, the diversity of customs, values and culture among the various societies around the world were vastly greater than the biological (genetic and phenotypic) diversity of all of those societies. This is still true today. We are all relatively identical biologically, but readily distinguishable culturally.

So I think that DIT does not fatally undermine Diamond’s thesis, but it could have been allocated more space as a proximate or secondary causality.

http://infoproc.blogspot.co.nz/2008/12/recent-natural-selection-in-humans.html

http://infoproc.blogspot.co.nz/2011/08/demography-and-fast-evolution.html