Cell: The Role of EDRA Gene in Evolution
The picture shows the mice carrying a human version of the EDAR gene have footpads with more sweat glands (blue tubes).
About 30,000 years ago, China was a warm and humid place. Thus people living here usually have more sweat glands to cool self temperature. But why and how is unclear to people.
Until six years ago, some scientists began to pay attention to a variant gene that involves in hair formation. In order to figure out how the genetic change in the gene caused the change in hair texture, researchers did a study on mice. The gene is EDAR. And its variant is EDAR 370A.
They inserted EDAR 370A into mouse embryonic stem cells. By breeding the resulting mice for several generations, they got a strain carrying 370A. Although the 370A protein differed from the mouse EDAR protein by just one amino acid, it led to several important changes in the mouse. The mice had thicker hairs in their fur, as expected. But they also had more sweat glands, denser mammary glands, and smaller fat pads around those mammary glands.
To determine if these effects were also found in people, the team measured sweat gland density in Han Chinese in China carrying one or two copies of 370A. People with a double dose of 370A also had more sweat glands, the researchers report. They did not have an easy way to tell if mammary glands were different in this group, but they suspect, based on the results in mice, that these structures were also affected.
Then they did genome analyses and computer simulations which indicated that the mutation creating the variant gene happened more than 30,000 years ago in central China. China had been relatively warm and humid between 40,000 and 32,000 years ago and then got cooler and drier.
The study is one of the first that clearly shows an important change in late human evolution which can be modeled in the mouse. The model is novel that helps people understand human evolution and the functional consequences of genetic changes.
Article Link: Cell: The Role of EDRA Gene in Evolution
