Sunday, March 12, 2006

Recent Evolution of Humans

The once-prevailing orthodoxy that human brain evolution stopped well before the rise of agriculture and cities is being rapidly swept away. "The Twists and Turns of History, and of DNA" an article by Nicholas Wade (New York Times , March 12, 2006) notes works showing that "a fresh look at history may be in order. Evolutionary changes in the genome could help explain cultural traits that last over many generations as societies adapted to different local pressures."....."The Yanomamo... and Ashkenazi Jews... may be examples of a society's genetic response to circumstances. Rice farming, practiced by East Asians for centuries, may have spurred evolutionary changes in physical and psychological traits."

Wade notes the recent book by Richard E. Nisbett "The Geography of Thought." It points out "East Asians tend to be more interdependent than the individualists of the West, which he attributed to the social constraints and central control handed down as part of the rice-farming techniques Asians have practiced for thousands of years." He cites work of Jonathan Pritchard, Univ. of Chicago, "In a study of East Asians, Europeans and Africans, Dr. Pritchard and his colleagues found 700 regions of the genome where genes appear to have been reshaped by natural selection in recent times. In East Asians, the average date of these selection events is 6,600 years ago."

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