Scientist’s Study Of Brain Genes Sparks a Backlash
Published by n1kk1 October 22nd, 2006 in Uncategorized. Tags: No Tags.Henry Harpending, a University of Utah anthropology professor who recently published a theory for why Ashkenazi Jews tend to have high IQ’s, says Dr. Lahn once suggested they co-author an article for Scientific American about the genetics of behavior, in which they could explain why “Chinese are boring.”
“I think that Bruce doesn’t understand political correctness,” Dr. Harpending says. Dr. Lahn says he only vaguely recalls the conversation but confirms that he wonders whether during China’s imperial times there was “some selection” against rebellious individuals.
In recent years, Dr. Lahn has become interested in why the human brain is so large and complex. Although humans and chimpanzees share about 96% of their DNA, human brains are about four times larger. Even today, researchers can find a correlation, on average, between people’s brain size and their IQ.
Dr. Lahn’s group zeroed in on the role of two genes, called ASPM and microcephalin, that are known to have a role in brain size. Humans with defective copies of either gene are born with brains only about one-third the normal size.
Studying DNA from several species, the Chicago team found that, over millions of years, the genes had undergone more rapid change in monkeys, apes and humans than in other animals. Their next step was to determine if evolution had continued in modern humans. Dr. Lahn’s graduate students began decoding DNA from 1,184 people belonging to 59 groups from around the world, including Bedouins, Pima Indians and French-speaking Basques.
The data showed that evolution had continued in recent millennia. A statistical analysis of DNA patterns suggested that new mutations in each of the two brain-related genes had spread quickly through some human populations. Evidently, these mutations were advantageous among those populations — just as the genetic variant promoting milk digestion was advantageous to early Europeans. Dr. Lahn and his team further observed that the new mutations are found most frequently outside of Africa.
What the data didn’t say was how the mutations were advantageous. Perhaps the genes play a role outside of the brain or affect a brain function that has nothing to do with intelligence.
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