our cannibal ancestors?

Our prehistoric ancestors may well have eaten human flesh regularly, John Collinge of University College London and his colleagues state in the April 11 Science. They say cannibalism is the most likely explanation for their discovery that genes protecting against prion diseases are common in the human population today. Prion diseases, such as kuru and Creutzfeldt-Jakob disease (the human version of mad cow), are caused by eating prion-contaminated flesh. The prions, which are misshapen proteins, cause healthy proteins to clump together fatally in the brain. According to the researchers, the protective genes could have provided early humans a better chance of surviving epidemics of diseases caused by the eating of human flesh. The researchers base their theory on the fact that the safeguarding genes are most common among the Fore people of Papua, New Guinea, who had a custom of eating their dead during funeral feasts. The researchers looked at the DNA of Africans, Asians, and Europeans, and all carried some form of the protective genes, suggesting prion disease epidemics were widespread among our ancestors. Natural selection would have favored people with the safeguarding genes, allowing them to survive these types of diseases. Other scientists remain unconvinced, arguing that the genes may have arisen as a defense against prion diseases carried by animals.

This news brief appeared in the Random Data column of the Boston Globe’s Health/Science section on 4/15/2003.