University of Chicago researchers say they've discovered the human brain is apparently still evolving. In two related papers published in the Sept. 9 issue of Science, they show that two genes linked to brain size are rapidly changing in humans.
"Our studies indicate the trend that is the defining characteristic of human evolution -- the growth of brain size and complexity -- is likely still going on," said lead researcher Bruce Lahn, an assistant professor of human genetics.
"Meanwhile, our environment and the skills we need to survive in it are changing ... (and) I would expect the human brain, which has done well by us so far, will continue to adapt to those changes," said Lahn.
Evolution, he said, doesn't occur at the species level. Rather, some individuals acquire a specific genetic mutation, and, because that variant confers on those who bear it a greater likelihood of survival, it then spreads in the population.
"We're seeing two examples of such a spread in progress," he said. "In each case, it's a spread of a new genetic variant in a gene that controls brain size. This variant is clearly favored by natural selection."
Copyright 2005 by United Press International
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