by In the middle of the 20th century, a mysterious disease occurred in the Eastern Highlands Province of Papua New Guinea which left all the villages without adult women.
The Fore people in the middle of the outbreak called him guru – the word tremor – because people lost control of their limbs and bodily functions before a tremor occurred before death.
The tribe was relatively isolated from the rest of the world until the 1930s, but at the height of the epidemic in the 1950s the attention of researchers from around the world was trying to understand the disease, which left it unexplained.
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After ruling out contamination, researchers hypothesized that it could be genetic, until it was discovered that kuru was spread through the Fore’s tradition of Mortuary Festivals, in which they ate the bodies of their deceased loved ones.
Kuru is a type of prion disease, a progressive neurodegenerative disease caused by a change in the shape of the body’s normal prion protein. The most likely explanation for its spread is that at some point one person died of a randomly occurring prion disease, such as sporadic Creutzfeldt-Jakob disease (CJD), and then the infected tissue was consumed by the public.
Because the body was broken up and eaten in a ritualistic way according to spiritual beliefs, with certain tissues going to certain relatives, women and children were the most affected by the disease – because they were divided on the brain and the spinal cord where prions are concentrated.
Epidemics of kuru subsided for years after the mortuary feasts were banned in the 1950s, but a research center in the United Kingdom dedicated to studying it has emerged after its own brush with an epidemic of prion disease.
The UK Medical Research Council’s flagship unit was set up at University College London after BSE (or “mad cow disease”), which occurred when cattle were pushed up and fed back to cattle, crossed the barrier species in 1995. with young people dying from variant CJD.
New research led by the unit and published this week in the American Journal of Human Genetics provides the most comprehensive genetic study of the people living in the Eastern Highlands to date, and also investigates the impact of the kuru epidemic on migration flows. in the region.
A new genetic analysis
It was previously thought that intermarriage between the Fore and neighboring communities decreased or even stopped entirely because they associated the disease with sorcery as a result of kuru.
The new genetic analysis found no evidence of less overall migration to the areas where kuru was most severe, or of a halt to the rural practice, where a wife moves to live closer to her husband’s family.
“On the contrary, we observed a significant bias towards females among migrants in areas of high kuru incidence,” the authors wrote. The analysis showed that the percentage of women among migrants was 25% higher in “high incidence” kuru areas compared to the “nil/low” kuru incidence areas.
“This is probably a reflection of the ongoing rural practice [where a newlywed couple lives near the husband’s family] despite the documented fears and pressures placed on communities as a result of kuru,” the paper concludes.
The Papua New Guinea Institute of Medical Research (PNGIMR) recruited field staff from the affected populations and neighboring communities to collect genetic samples through long-term community participation, which were then analyzed by researchers in London and Copenhagen.
It’s nice to find multiple ways to look at human societies and human populations
Dr Irene Gallago Romero
The researchers performed a genetic analysis of the region based on genome-wide genotype data of 943 individuals from 21 linguistic groups and 68 villages in the Eastern Highlands of Papua New Guinea, including 34 villages in the South Fore linguistic group, the group he most affected. guru
Laboratory studies were approved by the PNGIMR advisory committee and the UCL Institute of Neurology research ethics committee, with oral consent obtained from all participants before any samples were obtained, and involvement of the communities involved was established through discussions with village leaders, communities, families and individuals.
Earlier genetic research among the Fore people showed that surviving women carried genetic variants in the gene that encodes prion proteins, making them likely to be resistant to kuru.
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Professor Simon Mead, consultant neurologist and clinical head of the UK’s National Prion Clinic, said, “we found evidence that the Fore population was evolving to protect itself against the kuru epidemic, but the this region in the past, therefore. they could not make confident conclusions about evolution without a deeper knowledge of the genetics of the populations involved.”
Dr Irene Gallago Romero, a human genome and evolution researcher at St Vincent’s Institute for Medical Research, said the question of whether female migration was large enough to change the genetic make-up of traditional island communities was unanswered.
The study found that there is a “significant level of population structure”, or distinct genetic groups, in the region, but if strict village boundaries were broken down, less population structure would have been observed, it said. Romero.
She said it was “striking” how the study showed how genetics could add another dimension to the history of a group of people who are not well known.
“[Anthropology] and genetics tell largely complementary stories, but there are bits and pieces that are inconsistent.”
For example, the study found that some villages speaking different languages were genetically similar, and that different communities speaking the same language were genetically different.
“So it’s nice to have multiple ways of looking at human societies and human populations.”
Another main result was that there were significant genetic differences between language groups. Researchers found more differences between communities in Papua New Guinea than between Spain and Finland, even though some of these groups were only 45km apart. Gallago Romero attributed this to the practice of marriage within a small community.
Colin Masters, laureate professor of neuropathology at the University of Melbourne, said the study showed how pandemics and epidemics, in which millions of people die, can change the genetic code of a population.
