for National Geographic News
Summary: Genetic markers commonly found in modern humans all over the world could be evidence that our earliest ancestors were cannibals, according to new research. Scientists suggest that even today many of us carry a gene that evolved as protection against brain diseases that can be spread by eating human flesh.
The brain diseases, called prion diseases, are characterized by loss of coordination, dementia, paralysis, and eventually death. Modern examples include Creutzfeld Jacob disease and kuru in humans, and mad cow disease, or bovine spongiform encephalopathy, in animals.
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Fried human, barbecued human, broiled human, raw human…were these items on the menu of the day for our prehistoric ancestors? Quite possibly, according to genetic researchers.
Scientists from England, Australia, and Papua New Guinea say that cannibalism is the most likely explanation for their discovery that genes protecting against brain diseases that can be contracted by eating contaminated flesh have long been spread throughout the world.
A growing body of evidence, such as piles of human bones with clear signs of human butchery, suggests cannibalism was widespread among ancient cultures. The discovery of this genetic resistance, which shows signs of having spread as a result of natural selection, supports the physical evidence for cannibalism, say the scientists.
"We don't in fact know that all populations did select. The selection may have occurred during the evolution of modern humans before they spread around the world," said Simon Mead, a co-author of the study from the Medical Research Center with University College, London.
The research is published in the April 11 issue of the journal Science.
Prion Disease
The brain diseases, called prion diseases, are characterized by loss of coordination, dementia, paralysis, and eventually death. Modern examples include Creutzfeld Jacob disease and kuru in humans and mad cow disease, or bovine spongiform encephalopathy, in animals.
The diseases are caused by mishappen molecules that clump together and accumulate in brain tissue. These molecules, called prion proteins, normally reside on the surface of brain cells, though their function is unknown.
Scientists believe the mishappen prion proteins somehow cause normal prions to form incorrectly, making it easy for them to clump together. These clumps cause the formation of small cavities in the brain similar to holes in a sponge.
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