Study claims tubers, not meat, made early humans excel

William Atkins
Thursday, 20 September 2007 00:34

Science - Biology

New evidence shows amylase, an enzyme that breaks down starch into glucose in the mouth, may have helped to successfully evolve humans to their dominant position within living species on Earth.       

The saliva in the mouths of humans contains large amounts of amylase (another name for glycoside hydrolase enzymes), at least more of the gene than is produced by other animals. Today, humans have up to fifteen copies of the salivary amylase gene within their bodies. The more starch eaten by humans the more copies of the salivary amylase gene are found in saliva.

U.S. anthropologist Nathaniel Dominy, from the University of California at Santa Cruz, coauthored the study that appeared online beginning on September 9, 2007, and that will be published in a future issue of the journal Nature Genetics. Dominy says that starch from within tubers, corms, and bulbs provided important calories in the diets of early humans.

The researchers found that groups eating less starches, such as in aboriginal societies that rely more on fish and meat, carry less copies of the amylase. Thus, the societies that eat the most starch carry the maximum copies of the amylase gene (that is, fifteen).

In addition, for a long time, anthropologists thought that early humans increased their brain size, along with their overall physical size, by incorporating meat into their diets. However, it is difficult to capture animals for meat. It is a lot easier just to dig up tubers. Dominy and his fellow researchers think that humans evolved so efficiently because of tubers, not meat. Their study helps to add evidence to support the importance of tubers over meat in the evolution of humans.

To learn more about this interesting story, go to the Physorg.com website “Extra gene copies were enough to make early humans' mouths water”.