Researchers led by University of Chicago geneticist Bruce Lahn present findings in Science suggesting that the human brain has continued to evolve over the last 60,000 years or so. See stories here and here and here. These articles suggest that this is a surprising finding, though I would have been more surprised if this were not the case. What rightfully seems to be in dispute, however, is the manner in which the human brain has evolved. From the first NYT article:
Lahn and colleagues examined two genes, named microcephalin and ASPM, that are connected to brain size. If those genes don't work, babies are born with severely small brains, called microcephaly.
Using DNA samples from ethnically diverse populations, they identified a collection of variations in each gene that occurred with unusually high frequency. In fact, the variations were so common they couldn't be accidental mutations but instead were probably due to natural selection, where genetic changes that are favorable to a species quickly gain a foothold and begin to spread, the researchers report. . . .
For the microcephalin gene, the variation arose about 37,000 years ago, about the time period when art, music and tool-making were emerging, Lahn said. For ASPM, the variation arose about 5,800 years ago, roughly correlating with the development of written language, spread of agriculture and development of cities, he said.
The research has been controversial because the alleles, which arguably enhance cognitive function, are more common in some populations than others. The second NYT article notes:
[Dr. Lahn] said he expected that more such allele differences between populations would come to light, as have differences in patterns of genetic disease. "I do think this kind of study is a harbinger for what might become a rather controversial issue in human population research," Dr. Lahn said. But he said his data and other such findings "do not necessarily lead to prejudice for or against any particular population."
The wishy-washiness of the last quote seems to undermine its message, though I suppose the article may have lost some of the tone of the original statement.
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