New light on genetic roots: “Present day Europeans trace their ancestry back to three and not just two ancestral groups”

According to the study, the beginning of agriculture and animal domestication, which began in the Near East about 11,000 years ago, had a tremendous impact on human lifestyle. Hunter-gatherers were replaced in many places by sedentary farmers, and there were large increases in population size that laid the foundation for larger towns and eventually complex societies. Archaeological evidence suggests that the transition to a farming lifestyle in central Europe occurred around 7,500 years ago, with the appearance of the linearbandkeramik (LBK), a sedentary farming culture. It has long been debated whether that change in subsistence strategy involved the mass migration of people from the Near East bringing innovative technologies and domestic animals to Europe or whether it was due to a transmission of cultural practices passed on from neighbouring populations.

Recent genetic studies on ancient hunter-gatherers and early farmer remains have suggested a massive migration of people to Europe coinciding with the spread of farming. The size and distribution of the genetic components contributed to indigenous European hunter-gatherers, however, remain unclear.

An international consortium led by researchers from the University of Tubingen and Harvard Medical School, along with the scientists from the CSIR-Centre for Cellular and Molecular Biology (CCMB), Hyderabad, have analyzed ancient human genomes from a -7,000-year-old early farmer from the LBK culture from Stuttgart in Southern Germany, a -8,000-year-old hunter-gatherer from the Loschbour rock shelter in Luxembourg, and seven -8,000-year-old hunter-gatherers from Motala in Sweden.

In order to compare the ancient humans to present-day people, the team also generated genome-wide data from about 2,400 humans from almost 200 diverse worldwide contemporary populations, including the enigmatic tribal population of Andaman and Nicobar Islands, says Dr. Kumarasamy Thangaraj, one of the authors of this study and Senior Principal Scientist at the CCMB, Hyderabad.

Their surprising finding was that present-day Europeans trace their ancestry back to three and not just two ancestral groups: The first is an indigenous hunter-gatherers; the second is Middle Eastern farmers that migrated to Europe around 7,500 years ago; and a novel third is a more mysterious population that spanned North Eurasia and genetically connects Europeans and Native Americans. "We find a major surprise: Europeans are a mixture of three ancient populations, not two," says Dr. David Reich from Harvard Medical School, one of the lead investigators of the new study.

"By analysing the genomes of contemporary populations, we have previously found that the present day Indians have emerged from two ancestral populations (ASI-ancestral south Indians and ANI-ancestral north indians); while ASI do not have any genetic affinity outside India, ANI showed upto 70% genetic affinity with European". However, it would be interesting to see that which one of the three ancestral European populations is related to ANI, says Dr. Lalji Singh, Former Director, CCMB, and one of the authors of this study.