In the mid-20th century, the Eastern Highlands province of Papua New Guinea was ravaged by a mysterious disease that left entire villages without adult women.
The Fore people at the center of the outbreak called it kuru – the word for shivering – because people lost control of their limbs and bodily functions before a tremor that preceded death occurred.
The strain had been relatively isolated from the rest of the world until the 1930s, but by the height of the epidemic in the 1950s it had attracted the attention of researchers from around the world trying to understand the disease, which until then had escaped the statement.
Related: Deadly land conflicts in PNG’s highlands are leaving people in ‘constant fear’
After ruling out contaminants, researchers hypothesized that it might be genetic, only to discover that kuru was spread through the Fore tradition of mortuary feasts, which involved eating the bodies of their deceased relatives.
Kuru, a type of prion disease, is 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 from a randomly occurring prion disease, such as sporadic Creutzfeldt-Jakob disease (CJD), and the infected tissue was then consumed by the community.
Because according to spiritual beliefs the body was broken up and eaten in a ritual manner, with certain tissues going to certain relatives, women and children were most affected by the disease – as they were distributed throughout the brain and spinal cord where prions are concentrated.
The kuru epidemic waned for decades after mortuary parties were banned in the 1950s, but a research center in the United Kingdom has dedicated itself to studying it after their own encounter with an epidemic of prion disease.
The UK Medical Research Council’s prion unit at University College London was established in the wake of BSE (aka ‘mad cow disease’), which occurred when cattle were ground up and then fed back to livestock, and which crossed the species barrier in 1995. where young people die 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 examines the impact of the kuru epidemic on migration flows in the region.
New genetic analysis
Kuru was previously thought to lead to a decline or even a complete cessation of marriages between the Fore and neighboring communities, as they associated the disease with sorcery.
The new genetic analysis found no evidence of less common migration to areas where kuru was most severe, or of an end to the practice of patrilocality, where a bride moves to live closer to her husband’s family.
“On the contrary, we observed a significant preference for women among migrants in areas with high kuru incidence,” the authors wrote. The analysis found that the proportion of women among migrants was 25% higher in the “high” kuru incidence areas compared to the “zero/low” kuru incidence areas.
“This probably reflects the continued practice of patrilocality [where a newlywed couple lives near the husband’s family] despite documented fears and tensions placed on communities as a result of kuru,” the paper concludes.
Field staff from the affected and neighboring populations were recruited by the Papua New Guinea Institute for Medical Research (PNGIMR) to collect genetic samples through long-term community participation, which were then analyzed by researchers in London and Copenhagen.
It’s really nice to get multiple ways of looking at human societies and human populations
Dr. Irene Gallago Romero
The researchers conducted a genetic analysis of the region based on genome-wide genotype data from 943 individuals from 21 language groups and 68 villages in the Eastern Highlands of Papua New Guinea, including 34 villages in the South Fore language group, the group most affected is by kuru.
Laboratory studies were approved by the PNGIMR Advisory Committee and by the UCL Institute of Neurology Research Ethics Committee, with verbal consent obtained from all participants before samples were obtained, and participation of the communities involved through discussions with village leaders, communities , families and individuals.
Previous genetic research among the Fore population found that female survivors carried genetic variants in the gene encoding prion proteins, likely making them resistant to kuru.
Related: Between two worlds: life of PNG tribal leader and plantation owner honored
Professor Simon Mead, neurologist and clinical lead at the UK National Prion Clinic, said: “We found evidence that the Fore population evolved to protect itself from the kuru epidemic, but this region had been poorly studied in the past, so we I could not draw reliable conclusions about evolution without a deeper knowledge of the genetics of the populations involved.”
Dr. Irene Gallago Romero, a researcher in human genomics and evolution at St. Vincent’s Institute for Medical Research, said the question of whether women’s migration was drastic enough to change the genetic makeup of traditionally insular communities remained unanswered.
The study found “a striking degree of population structure,” or different genetic groups, in the region, but if the rigid village boundaries had indeed been broken, a smaller degree of population structure would have been observed, Romero said.
She said it was “striking” how the study illustrated how genetics could add a new dimension to the history of a relatively unknown group of people.
“[Anthropology] and genetics mostly tell 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 some communities speaking the same language were genetically different.
“So it’s really nice to get multiple ways of looking at human societies and human populations.”
Another important finding was the existence of drastic genetic differences between language groups. Researchers found a greater difference between communities in Papua New Guinea than between Spain and Finland, even though some of these groups were only 45 km apart. Gallago Romero attributed this to the custom of marrying within a small community.
Colin Masters, an award-winning professor of neuropathology at the University of Melbourne, said the study illustrated how pandemics and epidemics, which kill millions of people, have the potential to change the genetic code of a population.