Natural selection in action

Two days ago we saw the 150th anniversary of the publication of On the Origin of Species. I didn’t have the time to post anything on that momentous anniversary. However, a trawl through the Breaking News section on the Fortean Times website I found an excellent example of Natural selection in action.

On 21 November Science Daily reported on a paper published in The New England Journal of Medicine concerning a community’s developing resistance to the disease kuru.

Kuru is a fatal prion disease, similar to CJD in humans and BSE in animals, that is unique to an area in Papua New Guinea. In the mid 20th Century, an epidemic 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 Medical Research Council Prion Unit 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 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 in direct response to the epidemic. This is thought be perhaps the strongest example yet of recent natural selection in humans.

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 closer to understanding, treating and hopefully preventing a range of prion diseases."

Medical Research Council (UK) (2009, November 21). Brain disease 'resistance gene' evolves in Papua New Guinea community; could offer insights into CJD. ScienceDaily. Retrieved November 26, 2009, from http://www.sciencedaily.com¬ /releases/2009/11/091120091959.htm