Ok. So all my World War 2 examples have now decisively been shown to be wrong. I don't have any other modern examples to give that go in this direction. All other modern examples go pretty strongly in the other direction. I withdraw the claim wholesale and am updating to accept the claim for post-enlightenment human societies.
http://vimeo.com/22099396
What do people think of this, from a Bayesian perspective?
It is a talk given to the Oxford Transhumanists. Their previous speaker was Eliezer Yudkowsky. Audio version and past talks here: http://groupspaces.com/oxfordtranshumanists/pages/past-talks