Previously Unknown Hominin Discovered In Denisova Cave in Siberia

spelunking-for-denisovans

Excavation of Denisova Cave, a site overseen by the Russian Academy of Sciences, is an ongoing venture involving international teams of researchers.

The Denisova Cave, perched high in the Altai Mountains of southern Siberia, has been a large natural shelter for humans and animals for tens of thousands of years. Buried deep in the cave sediments, scientists discovered genetic material from a previously unknown hominin, dubbed Denisovans, who inhabited a large area of Asia and, just like the Neanderthals, mated with modern humans.

David Reich, a geneticist from Harvard Medical School, went to Siberia to confer with Russian archaeologists, who recently unearthed a pea-sized pinky bone from a Denisovan, who lived 30,000 to 50,000 years ago. The bone, along with an oversized adult molar, helped Reich et al. at HMS and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, identify the unknown hominin.

denisova-cave-molar-pinky-bone

The layers of sediment excavated in Denisova Cave (top left) and its surroundings have yielded such artifacts as chipping tools (top right), a fragment of a pinky bone, and a molar. DNA in the bone and molar led to the identification of a new hominin group, the Denisovans.

Reich wants to discover if the genes inherited in humans from Denisovans help protect humans from disease, thanks to the aid of super-fast sequencing and genotyping equipment. The team developed complex statistical algorithms to analyze gene-flow patterns.

Reich was part of a group of 20 geneticists, archaeologists, and paleoanthropologists from the USA, Asia, Europe and Russia who gathered to learn more about the Denisovans. Unlike Neanderthals, Denisovans aren’t present in the fossil record. This has led the Russian Academy of Sciences to establish a permanent camp near the cave.

The cave might have been a refuge for Denisovans, Neanderthals and humans alike, maybe at different points in time. The researchers were able to extract both mitochondrial and nuclear DNA. Denisovans are a more distant cousin to humans than Neanderthals, who are closely related to modern day humans. Denisovans are a sister group to the Neanderthals. Denisovans bred with ancestors of the present-day New Guineans and other Melanesians.

Denisovans lived across a vast area, from southern Siberia to Southeast Asia, and contributed genes to several populations in Southeast Asia and Oceania, including the Australian aboriginal people. Genetic traces of Denisovans weren’t found in mainland Asians.

It has been suggested that genes from Neanderthals and Denisovans helped boost the immune systems of future generations, by contributing alleles associated with the human leukocyte antigen system.

[via Harvard Medicine]

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