*Genes thought to affect IQ might not* Oct. 2, 2012 Courtesy of the Association for Psychological Science and World Science <http://www.world-science.net> staff
*Most of the genes long thought to be linked to intelligence, simply aren't, a new study has concluded.
"We are not saying the people who did earlier research in this area were foolish," said Christopher Chabris, a psychological scientist at Union College in New York who co-led the study. "They were using the best technology and information they had available."
Nor do Chabris and his colleagues deny that intelligence is hereditary and genetic. But they say it now turns out that this intangible quality is probably too complex to sum up in a few genes. It may be some time before researchers can identify intelligence's specific genetic roots, say the researchers, whose findings are published online in the research journal /Psychological Science/.
Chabris and David Laibson, a Harvard economist, led an international team of researchers that analyzed a dozen genes using large data sets that included both intelligence testing and genetic data. In nearly every case, the researchers found that intelligence could not be linked to the specific genes tested.
"We only found one gene that appeared to be associated with intelligence, and it was a very small effect. This does not mean intelligence does not have a genetic component. It means it's a lot harder to find the particular genes, or the particular genetic variants, that influence the differences in intelligence," said Chabris.
It had long been believed, on the basis of studies of identical and fraternal twins, that intelligence was a heritable trait. The new research affirms that conclusion. But older studies that picked out specific genes had flaws, Chabris said, primarily because of technological limits that prevented researchers from probing more than a few locations in the human genome to find genes that affected intelligence.
Also, "at the time, it was believed that individual genes would have a much larger effect --- they were expecting to find genes that might each account for several IQ points," Chabris explained. IQ is a widespread measure of intelligence in which average intelligence is scored as 100, while higher or lower intelligence are scored higher or lower. The score is meant to measure a person's intelligence as compared to the average for their age group, as a percentage.
Chabris said additional research is needed to determine the exact role genes play in intelligence.
"As is the case with other traits, like height, there are probably thousands of genes and their variants that are associated with intelligence," he said. "And there may be other genetic effects beyond the single gene effects. There could be interactions among genes, or interactions between genes and the environment. Our results show that the way researchers have been looking for genes that may be related to intelligence --- the 'candidate gene' method --- is fairly likely to result in false positives, so other methods should be used."**
http://www.world-science.net/othernews/121002_intelligence *Natalia* *
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