India is a hodgepodge of languages, religions, cultures and genetic lines. Image: Oct11988duh, Wikipedia
Reading aloud An analysis of the genetic differences among 25 Indian ethnic groups provides a surprising finding: only two different primitive populations have produced the enormous genetic diversity of the subcontinent. From each of a northern and a southern ethnic group have split off after the colonization of India individual groups, which remained isolated for thousands of years by the caste system and the precisely regulated marriage customs. Therefore, although all groups are derived from the same two populations, they differ significantly in their genetic characteristics. The researchers examined more than 560, 000 genetic markers from a good 130 individuals from different ethnic groups. With this range of data they could cover all language families, castes and tribes making the Indian population a very heterogeneous society. The scientists found that all individuals studied are descendants of two genetic groups: a North Indian and a South Indian native population. The North Indian has an ancient relationship to European ethnic groups, while the South Indian only with an already extinct tribe? the so-called Onge, who lived on the archipelago of the Andaman Islands? has more in common.

Despite this descent of only two genetic strains, today's Indian society is breaking up into many small groups. They are apparently not only culturally and geographically isolated from each other, but also genetically. The researchers attribute this to the so-called founder effect. Thus, when a new population is created by a few individuals, a group with significantly reduced genetic diversity is created. Moreover, if the newly formed populations do not remix, they will genetically evolve in different directions due to the different source material. That's exactly what has happened in India since its settlement some 60, 000 years ago.

On the one hand, it would be possible to identify the genetic ancestors of a group by the genome of a few members, the researchers draw a first conclusion from their study. On the other hand, it is difficult to give an overview of the genetic diversity of the entire Indian population. In addition, the scientists suspect that many hereditary diseases are widespread in India, because the founder effect may have similar effects as inbreeding. The genetic material of individual families or groups is not mixed during reproduction, which leads to an accumulation of disease genes. The researchers were also able to confirm that the individual castes developed from ancient tribes and did not have their own caste system in each tribe.

David Reich (Harvard University, Boston) et al .: Nature, Vol. 461, p. 489 ddp / science.de - Martina Bisculm advertisement

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