Geneticists have analyzed the DNA of more than a hundred representatives of the Raute ethnic group, the last hunter-gatherers of the Himalayas. The researchers found that 50 generations ago, the effective population size of these people's ancestors was stable and reached about 2,500 people. However, then, about 1,500-1,100 years ago, there was a sharp decline, as a result of which this figure decreased by about 25 times. This is reported in the journal Scientific Reports.
In the northwest of modern Nepal, in the Karnali zone, live the last hunter-gatherers of the Himalayas - the Raute ethnic group. The nomadic Raute are short, dark-skinned people, numbering about 140 people. They gather wild plants and hunt mainly small monkeys, regularly migrating from place to place in search of food sources. In addition, they exchange their products (for example, large wooden vessels or boxes) with neighbors for rice, iron and other things. In recent times, the Raute are willing to accept help, but, according to eyewitnesses, they are willing to spend the money they receive or earn on alcohol.
There is little historical information about the origins of the Raute. To add some clarity, Inez Derkx from the University of Zurich, together with colleagues from Spain, Nepal, the Czech Republic and Switzerland, sequenced the DNA of 120 representatives of the Raute ethnic group and 47 people living in the same rural area. However, seven DNA samples from the Raute and three other people did not pass quality control and were excluded from further study. In addition, the scientists faced a problem: due to strict endogamy, only two of the Raute were not closely related to each other, which is important for population studies. Relaxing the standard selection criteria allowed the sample to be expanded for some analyses to ten people.
To find out how the effective population size of this population changed over time, the scientists turned to the GONE program, which allows them to calculate this figure for the last 100 generations. The researchers found that for a long time - up to about 50 generations ago - the effective population size of the ancestors of Raute remained stable and reached about 2,500 individuals. However, over the course of just ten generations, there was a very sharp decline - by about 25 times. If we consider the length of one generation to be 29 years, then this sharp drop occurred approximately 1,500-1,100 years ago. After the sharp decline, the effective population size of the ancestors of Raute remained low, but relatively stable.
The scientists also settled on the origins of the Raute ancestors. They found no discernible signs that these people were descendants of isolated local hunter-gatherers who lived in the region before farmers and herders arrived. Instead, they are genetically similar to their neighbors, not only to those populations that were hunter-gatherers in the relatively recent past (150–300 years ago) — the Taru and Kusunda — but also to those who have been farming for the past several thousand years.
It is possible that the Raute ancestors abandoned the food-producing economy and returned to hunting and gathering after they had already arrived in the Himalayas. But the authors of the article consider this scenario unlikely, leaning towards the idea that the Raute gene pool was probably formed as a result of a long process of mixing between farmers who arrived in the region and local hunter-gatherers, as a result of which noticeable traces of the latter disappeared.
Earlier, N + 1 reported how geneticists studied the DNA of the indigenous people of Papua New Guinea. This analysis showed that the lines of European Cro-Magnons and the indigenous people of East Asia separated from the ancestors of the Papuans about 51.2–46.2 thousand years ago.
