Tuesday, December 02, 2014
Ability To Consume Alcohol May Have Shaped Primate Evolution
“The fact that they could put together all this evolutionary history was really fascinating,” says Brenda Benefit, an anthropologist at New Mexico State University, Las Cruces, who was not involved in the study.
Scientists knew that the human ability to metabolize ethanol—allowing people to consume moderate amounts of alcohol without getting sick—relies on a set of proteins including the alcohol dehydrogenase enzyme ADH4. Although all primates have ADH4, which performs the crucial first step in breaking down ethanol, not all can metabolize alcohol; lemurs and baboons, for instance, have a version of ADH4 that’s less effective than the human one. Researchers didn’t know how long ago people evolved the more active form of the enzyme. Some scientists suspected it didn’t arise until humans started fermenting foods about 9000 years ago.
Matthew Carrigan, a biologist at Santa Fe College in Gainesville, Florida, and colleagues sequenced ADH4 proteins from 19 modern primates and then worked backward to determine the sequence of the protein at different points in primate history. Then they created copies of the ancient proteins coded for by the different gene versions to test how efficiently each metabolized ethanol. They showed that the most ancient forms of ADH4—found in primates as far back as 50 million years ago—only broke down small amounts of ethanol very slowly. But about 10 million years ago, the team reports online today in the Proceedings of the National Academy of Sciences, a common ancestor of humans, chimpanzees, and gorillas evolved a version of the protein that was 40 times more efficient at ethanol metabolism.
Full story here.