It's not just humans who practice cannibalism: birds, certain flies, our close cousins the chimpanzees, and even bacteria eat their own kind. Intelligent species, like humans, may eat each other for psychological or religious reasons. Chimps seem to do it in a fit of revenge or just plain nastiness, as when females eat other mothers' babies. Lions do it to preserve their genetic line?when a male takes over a pride, he eats the previous king's cubs. Praying mantises do it as part of good sex: At the end of the sex act, the female bites the head off her mate and eats him.
Bacillus subtilis bacteria produces an antibiotic that pops open its relatives so it can digest them. This seems to be the lowest order that engages in cannibalism. Harvard's Richard M. Losick says that which bacteria get eaten happens "just by chance. Some start down the road faster than others."
Human cannibalism has gone on all over the world. Archeological sites have been found with defleshed skulls, bones with shiny "pot polish," femurs cracked for marrow and even petrified human feces with traces of human muscle in it. And it?s still going on: Pygmies from the Democratic Republic of Congo have begged the UN to protect them from being eaten by rebel fighters.
Some ethnic groups in New Guinea, where cannibalism has gone on for many years, have evolved DNA that protects them from infection by prions, which cause a human form of Mad Cow Disease. For about 100 years, the Fore people of Papua New Guinea ate their deceased relatives. They developed an epidemic of kuru, a prion disease, which killed more than 200 of them a year?especially the women, who ate brains while men ate muscle. A study of 30 elderly Fore women who survived showed that 23 of them had the prion-protection gene.
"Muti murders," in which people are killed and their lips, tongues and other body parts are harvested for traditional medicine ("muti") still go on in South Africa. Last year, a man was arrested there for trying to sell a head for $1,000, and a morgue attendant was caught trying to sell two human hands for $400.
Some people eat human placentas?there are vegetarians who think of them as meat that doesn't involve killing. Some mothers think it helps the uterus contract. A British website for older mothers gave a recipe for roast placenta in tomato sauce.
Scientists can't find any biological advantage in cannibalism, since it increases the danger of genetic diseases even more than marriage with close relatives. It may be caused by a lack of (other) food. Biologist David W. Pfennig found that some kinds of salamanders eat each other when there's nothing else available. He says, "Disease is something you can potentially overcome, but starvation is pretty permanent." He's even found cannibal tadpoles that can identify the taste of their close relatives, so they can spit them out.
People can devour us in psychic ways as well.
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