What the genes reveal about the last hunter-gatherer groups

In the rainforest of southern Thailand live the Maniq, one of the last hunter-gatherer communities in the world. Austrian researchers have now deciphered their evolutionary genetic history and have come across surprising results. As they report in the journal Genome Biology and Evolution, the Maniq have one of the strongest genetic differentiations of any human population.

A small community, the Maniq live in the forested hills of southern Thailand, and the population is estimated at around 300 individuals. Culturally, the Maniq are counted among the Semang groups, which can otherwise be found on the Malay Peninsula. However, the demographic history of the region has long been the subject of scholarly debate due to the complex relationships between the various societies on the Southeast Asian mainland.

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A research team led by Tobias Göllner from the Department of Evolutionary Anthropology at the University of Vienna and Maximilian Larena from the University of Uppsala (Sweden), together with Thai colleagues, has now gained new insights into the Maniq and their relationships with other indigenous groups on the Southeast Asian mainland. Thanks to the Viennese cultural anthropologist Helmut Lukas’ longstanding ties to the group and the involvement of the Maniq, they were able to study genetic material from members of the group. The researchers then compared this data with DNA samples from present-day populations from the region as well as with genetic material from Stone Age populations as well as from Neanderthals and Denisovians.

“One of our main conclusions is that the Maniq have been in the region for a very long time and have maintained a very isolated population,” Goellner told APA. The scientists conclude that the long foreclosure is due to the “extreme genetic drift that we have found in the Maniq”. The background to this drift effect is normal mutations in the genome that happen all the time. “These are mostly neutral mutations that do not result in any change in biological fitness and that accumulate strongly over time in a closed population,” says Göllner. This genetic differentiation of the Maniq is one of the strongest known worldwide.

Long isolation

For the researchers, this is a clear signal of a long history of geographic and cultural isolation, a historically small population size, and the cultural practice of the Maniq of marrying largely within their own society. This scientifically confirms an assumption that has long been made by cultural and social anthropologists, says the biologist, who carried out the work as part of his PhD studies at the University of Vienna.

Looking further back in the Maniq lineage, there are also traces of the Hòabìnhian, a Middle Stone Age hunter-gatherer society that lived in present-day Vietnam more than 10,000 years ago. While portions of Neanderthal DNA are found in the Maniq genome, no traces of Denisova genome have been found. According to Göllner, this result is not atypical for the region, but it is still a large field of scientific discussion.

To confirm all of these results, Göllner wants to conduct further studies with larger samples or full genome sequencing data. He points out that hunter-gatherer communities have so far been poorly recorded in genomic studies and that, given the difficult current situation of the Maniq, this is “important evidence of one of the last hunter-gatherer populations”. In addition, the research team aims to gain insight into the important genetic adaptation traits of hunter-gatherers and how they differ from populations that have transitioned to an agricultural, modern lifestyle.

Negative pressure

Göllner emphasizes that future work with the Maniq will become more and more difficult “as society is coming under increasing pressure due to external factors”. In addition to discrimination and the intrusion of outsiders into their living space, the deforestation of the rainforest is a central problem.

“The Maniq are very de-escalative and would never tell anyone, ‘You can’t come here.’ The social form of hunters and gatherers is probably the most original way in which people lived together. However, if current developments continue, it will no longer be possible to maintain the nomadic lifestyle.

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