Jared Diamond in his famous text actually has has a throw away reference to this, where he speculates that New Guinea tribesmen are actually much smarter than Europeans because New Guinea tribesmen live by their wits, whereas Europeans it was their gut bacteria that determined whether they survived or not. And I actually knew that cities in Europe had very poor survival rates, that that’s where the educated people were, and I expected going into this to show that we were all, the current Europeans, were the remnants of rural idiocy.
Clark’s subsequent findings of the higher fertility of the rich and his association of this with the Industrial Revolution make this a relatively rare example in economics where someone can say that the evidence changed their mind.
Clark also makes some interesting comments on how he approached the genetic question in the book:
I must admit that when I wrote the book I was a little hesitant and so I talked about cultural or genetic link. That led to a firestorm of criticism and it led me to actually examine that proposition more carefully and I’ve actually come to realise that I was being too hesitant. There’s absolutely a genetic link. We absolutely have changed genetically over this pre-industrial period.
Finally, Clark on human ecology and the policy implications (which has some relevance to my earlier post):
There may be some groups that do face a disadvantage in operating in a capitalist economy, that their ecology is just not that of modern capitalism. But what I would argue is that might help us have some more understanding of why, these groups are not just being resistant or indolent. That really we have to understand that people have their own ecology and that these things are very hard to change suddenly.