The function of this region of DNA is still unknown, but it appears to be directly involved in the development of the human brain. "It's very exciting to use evolution to look at regions of our genome that haven't been explored yet," said Howard Hughes Medical Institute investigator David Haussler, the leader of the team that included scientists from the University of California, Santa Cruz, the University of California, Davis, the University of Brussels, and Université Claude Bernard in France.
Their article will be published in an advance online publication on August 16, 2006, in the journal Nature.
Haussler's group found the DNA region using a technique developed by Katherine Pollard, a former postdoctoral fellow in Haussler's lab who is now an assistant professor at the University of California, Davis. Pollard compared the DNA sequences of chimps, mice, and rats to find the regions that had remained largely unchanged over the 80 million years or so since the common ancestor of those organisms. She then examined the same regions in humans to identify those that had changed markedly in the 6 million years since humans and chimps diverged from a common ancestor.
"Some DNA regions have hardly changed at all over many millions of years in most species," said Pollard. "My twist was to look for the subset of these regions that have changed just in humans."
Forty-nine regions, which the team called human accelerated regions (HARs), rose to the top of the list. Surprisingly, only two of these regions code for proteins. Instead, the majority of the regions tend to be located near genes
Source:Howard Hughes Medical Institute