Human DNA Enlarges Mouse Brains

Researchers have increased the size of mouse brains by giving the rodents a piece of human DNA that controls gene activity. The work provides some of the strongest genetic evidence yet for how the human intellect surpassed those of all other apes.

"[The DNA] could easily be a huge component in how the human brain expanded," says Mary Ann Raghanti, a biological anthropologist at Kent State University in Ohio, who was not involved with the work. "It opens up a whole world of possibilities about brain evolution."

For centuries, biologists have wondered what made humans human. Once the human and chimp genomes were deciphered about a decade ago, they realized they could now begin to pinpoint the molecular underpinnings of our big brain, bipedalism, varied diet, and other traits that have made our species so successful. By 2008, almost two dozen computerized comparisons of human and ape genomes had come up with hundreds of pieces of DNA that might be important. But rarely have researchers taken the next steps to try to prove that a piece of DNA really made...