Cannibalism may have killed Neanderthals

Neanderthals who practiced cannibalism may have spread a mad cow-like disease that weakened and reduced populations, thereby contributing to their extinction, according to a new theory.

The theoretical model could resolve the longstanding mystery of what caused Neanderthals, which emerged about 250,000 years ago, to disappear about 30,000 years ago.

"The story of Neanderthal extinction is one of the most intriguing in all of human evolution," says Simon Underdown, a lecturer in the anthropology department at Oxford Brookes University and author of a paper in the journal Medical Hypotheses.

"Why did a large-brained, intelligent hominid that shared so many traits with us disappear?"

To resolve that question, Underdown studied a well-documented tribal group, the Fore of Papua New Guinea, who practiced ritualistic cannibalism and linked that to what could have happened to the Neanderthals.

Evidence of cannibalism

Gory evidence uncovered in a French cave in 1999 reveals Neanderthals probably practiced cannibalism too.

The 100,000-120,000 year-old bones discovered at the cave site of Moula-Guercy near the west bank of the Rhone river suggests a group of Neanderthals defleshed the bones of at least six other individuals and then broke the bones apart with a hammer stone and anvil to remove the marrow and brains.

It's not clear why Neanderthals may have eaten each other. But research on the Fore determined that maternal kin of certain deceased Fore individuals used to dismember corpses and regarded some human flesh as a valuable food source.

Beginning in the early 1900s, anthropologists also began to take note of an affliction among the Fore named kuru. By the 1960s, kuru reached epidemic levels and killed over 1100 people.

Subsequent investigations determined that kuru was related to the Fore's cannibalistic activities and was a form of transmissible spongiform encephalopathy or TSE.

TSEs, of which mad cow disease or bovine spongiform encephalopathy is one, have been around for possibly millions of years, Underdown says.

TSEs cause brain tissue to take on an almost sponge-like appearance, caused by the formation of small holes during the development of the disease.

The disease's latter stages often result in severe mental impairment, loss of speech and an inability to move.

How many could the disease kill?

Underdown created a model, based on the kuru findings, to figure out how the spread of such a disease via cannibalism could reduce a population's size.

For example, he calculated that within a hypothetical group of 15,000 individuals, such a disease could reduce the population to non-viable levels within 250 years.

When added to other pressures, this type of disease could therefore have wiped out the Neanderthals, Underdown believes. - abcsci