[freebeard]

The answer may not lie in the human genome per se:

Gut Bacteria In Amazonian Tribe Reveals New Information On Human Microbiome : T-Lounge : Tech Times

Some of the bacteria seen in the Venezuelan villagers had never before been seen in human beings. Human bodies contain trillions of bacteria, many of which are beneficial, assisting in the digestion of food, fending off disease-carrying microbes and strengthening the immune system.

See also: 'fecal transplant'.