“Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity.
“Our study denies the widely held assumption that modern humans appeared 40,000 years ago, have not changed since and that we are all pretty much the same. We aren’t the same as people even 1,000 or 2,000 years ago.”
The scientists said this reflected the great increase in human populations over that period, which has allowed more beneficial mutations to emerge. Changes in the human environment, particularly the rise of agriculture, also created new selective pressure to which humans adapted.Examples of evolutionary divergences include lactose tolerance among descendents of northern European populations (where the lack of sunlight would have made this mutation beneficial), differences in resistance to diseases such as malaria, smallpox and HIV between European and African populations, and more controversially, the hypothesis that above-average intelligence in Ashkenazi Jews is a result of selection pressures in mediaeval Europe (where they were confined to a small number of primarily cognitively demanding vocations). (And wasn't there a study a while ago that showed that the average IQ of a population was proportional to how many generations their ancestors had lived in urban environments?)
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