Cannibalism proves natural selection in humans
Brain Disease 'Resistance Gene' Evolves in Papua New Guinea Community; Could Offer Insights Into CJD
ScienceDaily (Nov. 21, 2009) — A community in Papua New Guinea that suffered a major epidemic of a CJD-like fatal brain disease called kuru has developed strong genetic resistance to the disease, according to new research by Medical Research Council (MRC) scientists. The findings are thought be perhaps the strongest example yet of recent natural selection in humans.
Kuru is a fatal prion disease, similar to CJD in humans and BSE in animals, and is geographically unique to an area in Papua New Guinea. In the mid 20th Century, an epidemic of kuru devastated a population in the Eastern Highlands of Papua New Guinea. The infection was passed on at mortuary feasts, where mainly women and children consumed their deceased relatives as a mark of respect and mourning. This practice was banned and ceased in the late 1950s.
Scientists from the MRC Prion Unit, a national centre of excellence in prion diseases, assessed over 3000 people from the affected and surrounding Eastern Highland populations, including 709 who had participated in cannibalistic mortuary feasts, 152 of whom subsequently died of kuru. They discovered a novel and unique variation in the prion protein gene called G127V in people from the Purosa valley region where kuru was most rife.
This gene mutation, which is found nowhere else in the world, seems to offer high or even complete protection against the development of kuru and has become frequent in this area through natural selection over recent history, in direct response to the epidemic.
Lead author Professor John Collinge, Director of the MRC Prion Unit said: "It's absolutely fascinating to see Darwinian principles at work here. This community of people has developed their own biologically unique response to a truly terrible epidemic. The fact that this genetic evolution has happened in a matter of decades is remarkable. Kuru comes from the same disease family as CJD so the discovery of this powerful resistance factor opens up new areas for research taking us closer to understanding, treating and hopefully preventing a range of prion diseases."
The study, which began in 1996, is published in the New England Journal of Medicine.
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