Human flesh may have been a fairly regular menu item for our prehistoric ancestors, according to researchers. They say it's the most likely explanation for their discovery that genes protecting against prion diseases -- which can be spread by eating contaminated flesh -- have long been widespread throughout the world.

The genes, which are mutant versions of the prion protein gene, show key signs of having spread through populations as the result of natural selection, the researchers report in the journal Science, published by the American Association for the Advancement of Science. Such mutations, or "polymorphisms," could have provided prehistoric humans a better chance of surviving epidemics of prion diseases, similar to modern day diseases such as Creutzfeld Jacob disease, or kuru.

"What we're showing here is evidence that selection for these polymorphisms has been very widespread or happened very early in the evolution of modern humans, before human beings spread all over the planet," said study author John Collinge of University College London. "We can't say which of those it is; but the obvious implication is that prion disease has provided the selection pressure."

Prion diseases are caused by misfolded versions of the prion protein, which cause other prion proteins to misfold and clump together in the brain. Kuru and Creutzfeld Jacob disease, in humans, as well as bovine spongiform encephalopathy, or BSE, in cows, cause brain degeneration and, ultimately, death.

In a previous study, Collinge and his colleagues determined that people with one normal copy and one mutated copy of the prion protein were somehow protected against Creutzfeld Jacob disease. The mutation consisted of a single amino acid substitution at a certain spot in the gene, and is known as "M129V." Among the Japanese and other
'"/>

Contact: Lisa Onaga
lonaga@aaas.org
202-326-7088
American Association for the Advancement of Science
10-Apr-2003