Why 2 percent is a world of difference

Genomically speaking, we are 98 percent chimp, and for decades, biologists have puzzled over how this small genetic modification could create such vastly different creatures.

To explore this question, Kevin P. White, Ph.D., associate professor of genetics, and his colleagues developed a gene chip to compare the activity of more than 1,000 genes from humans, chimpanzees, orangutans and rhesus macaques, four species spanning 70 million years of evolution.

As reported in the March 9 issue of Nature, the team found that genes that code for regulatory proteins are four times more likely to have increased their expression during human evolution than those that govern housekeeping or metabolic functions.

Monkeying with gene regulators can give rise to dramatically different new traits, like brain size or body shape, because the proteins serve as master switches that influence the activity of many other genes. “For 30 years scientists suspected that gene regulation has played a central role in human evolution,” says White. “This helps open the door to a functional dissection of the role of gene regulation during the evolution of modern humans.”