Cannibals survived brain disease epidemic thanks to a mutation
Published: 20 November, 2009, 17:40
Edited: 05 October, 2010, 23:25
TAGS: Health, SciTech, Thrills&Spills, History
Survivors of the deadly epidemic of prion disease kuru, which was transmitted through cannibalistic rituals, share a particular genetic mutation. Researchers call it a striking example of human evolution in action.
Kuru was a slow-developing epidemic among the Fore tribe in Papua New Guinea, which devastated the population in 19th and first half of the 20th Centuries. Victims suffered from progressively more severe neurological conditions as the disease developed, and it was dubbed “laughing sickness” by journalists for allegedly causing outbursts of unmotivated laughter.
Kuru was revealed to be transmitted through cannibalistic feasts practiced by the tribesmen upon their relatives who died from the disease. When such rituals were forbidden in the late 1950s, the epidemic stopped.
It was not until 1982 when its true cause was discovered. A special kind of proteins called prions, which are normally present in human brain, can get misfolded into a highly-stable pathogenic form. Moreover, they can cause normal proteins to misfold too, spreading the disease.
This leads to the brain transforming into a sponge-like mass and ultimately kills the victim. So far, there is no cure for diseases caused by prions, which include the rare Creutzfeldt-Jakob disease in humans and the notorious BSE, better known as Mad Cow Disease.
A group of researchers at the British prion research centre at University College London have discovered that the surviving Fore share a common mutation in the PRNP, the gene expressing prions.
The team, led by Simon Mead, performed genetic and selected genealogic assessment of more than 3,000 persons from the area affected by kuru, including more than 700 cannibalistic rites participants, 152 of whom subsequently died of the disease.
In 51 survivors of the epidemic and their descendants, they’ve discovered a previously-unknown variant of a section of PRNP. None of the victims had the mutation. Moreover, the bloodlines of the mutation carriers suffered from kuru about six times less than bloodlines of those without it.
In their work, published in The New England Journal of Medicine, Mead and colleagues say that the mutation is an acquired prion disease resistance factor, which underwent positive selection during the decades of epidemic.
"I hope it will become a textbook example of how evolution happens," said Mead.
20.11.2009, 13:38
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@Jesuslovesyou I have taken multiple classes on the bible and I have taken countless classes on genetics and evolution. Saying something is a theory means that there is a plethora of evidence for said theory and no doubt. The Pythagorean Theorem is also a theory but I will challenge you to prove it wrong. You can't. Evolution does not prove religion wrong in any way. It is just an adaptation to a changing environment over time. It can be short term or long term. I cannot say for sure we were descended from monkeys but our genetic structure is extremely similar. Amazingly similar. An example that does prove evolution is the peppered moths of England. They started out very light to blend into the trees so they would not be eaten. Pollution increased and soot turned the trees darker. The light moths stood out and were eaten. The survivors bred and their genes made some of the moths turn darker and darker from pigment genes and they survived while their lighter siblings were eaten. This created a greater chance for the darker moth's offspring to be darker. Therefore they adapted to their changing environment so they could survive. This happened in 30 years time. How can you see that and say evolution is not true?
@Jesuslovesyou
Unfortunately in society there is a gross misunderstanding of the scientific method.
One such aspect is in scientific nomenclature a "theory" is the highest form of proof possible while something that iasn't established as a fact is called a hypothesis.
Take the theory of gravity for example. It's a just a theory! But do certain groups of people outside the scientific arena dispute gravity because it's just a theory? Apparently not! It appears they don't give it a second thought.
However, in informal English the words "theory" and "hypothesis" have become interchangable which leads to the misconception a "theory" refers to something that is unproven.
Now whether evolution is possible I'm not going to comment, but it appears you also don't know what a theory is in the scientific context in which its being discussed.
=P