In 1999, I started an email group to discuss human biodiversity. Fortuitously, my project happened to bring Henry into contact for the first time with the physicist Gregory Cochran, who had developed an interest in applying and extending evolutionary theory. Together, they went on to set off sparks that might someday be recognized as the leading intellectual development of the early 21st century.
Their overarching breakthrough was the realization that the rapid development of human culture since the invention of agriculture roughly 10,000 years ago doesn’t mean that Darwinian evolution slowed down, as was nearly universally assumed in the late 20th century. Instead, the development of new and different cultural pressures on different continents implied that selection must have sped up, increasing the biodiversity of humanity.
In 2005, they illustrated their general thesis with a stunning paper on “The Natural History of Ashkenazi Intelligence.” One of the great scientific papers of the age, it elicited admiring attention from Steven Pinker and Nicholas Wade. Henry and Greg noted that the proliferation of European Jewish genetic diseases such as Tay-Sachs and torsion dystonia are likely offshoots of selection pressure for literacy and numeracy in white-collar occupations in medieval Europe. Just as black Africans are more prone to sickle-cell anemia because it’s a quick and dirty malaria-fighting mutation, European Jews may have evolved IQ-boosting mutations that extract a medical price.
