Approximately two to three million years ago, the first primate moved from the forest to the savannah. He has grown longer legs, bigger muscles and wider feet. Then he developed sweat glands, which allowed him to cool off under the scorching African sun. According to recent studies, a single gene mutation called CMAH spread throughout the species around this time. Now, a study in rodents supports the idea that this genetic refinement allowed humans to run long distances and drive their prey to exhaustion.
According to biologist Ajit Varka of the University of California, San Diego, the mutation rendered the CMAH gene completely inactive. Varki wondered if there was a connection between this genetic event and the ability to run long distances. Since everyone has this non-functional gene, they couldn't simply compare the running ability of different people. However, he spent years studying mice that developed the same CMAH mutation as humans to shed light on the development of diabetes, cancer and muscular dystrophy. Varki's work suggested a link between CMAH loss and muscle biology, but he needed proof.
Gene disabling was beneficial
“For about 10 years, I've been trying to convince someone in my lab to put these mice on a treadmill,” says Varkey. When he finally performed the experiment, "lo and behold, without any training, mice without CMAH ran 1.5 times better." The rodents' muscles - especially their hind legs - used oxygen more efficiently and were less tired. The results of the work were published in Proceedings of the Royal Society B.
In 2004, Harvard biologist Daniel Lieberman suggested that running - as opposed to just walking on two legs - played an important role in human evolution. Lieberman, who was not involved in this new mouse study, says it is "the first really good and thorough genetic study that fits our predictions" about the role of running in the heyday of modern humans.
Ilya Khel