A single gene duplication helped human brains become complex, reveals study.
Surprisingly, the added copy doesn't augment the function of the original gene, SRGAP2, which makes neurons sprout connections to neighboring cells. Instead it interferes with that original function, effectively giving neurons more time to wire themselves into a bigger brain.
"This appears to be a major example of a genomic innovation that contributed to human evolution," said Franck Polleux, a professor at The Scripps Research Institute. "The finding that a duplicated gene can interact with the original copy also suggests a new way to think about how evolution occurs and might give us clues to human-specific developmental disorders such as autism and schizophrenia."
Polleux is the senior author of the new report, which was published online ahead of print on May 3, 2012 by the journal Cell
. The same issue features a related paper on SRGAP2's recent evolution by the laboratory of Evan E. Eichler at the University of Washington, Seattle.