An archaic tooth gives meaning to the theory of miscegenation between different types of humans

An unusual old tooth discovered in China reinforces the theory that Homo sapiens and an extinct human species, the Denisovans, exchanged genetic material – and physical traits – thousands of years ago.

The tooth, a molar with three roots, belonged to a jaw remarkably high in a mountain cave on the Tibetan plateau. Anthropologists have announced the discovery of the jaw, which preceded 100,000 years of modern human settlement in the region in May. A new article, published last week in the Proceedings of the National Academy of Sciences, is the first to describe in detail the tooth with three roots of the jaw.

Three roots in a lower molar are rare in modern humans. The overall prevalence among non-Asians is about 3.5%. In Asian and Amerindian populations, however, the proportion of three-rooted molars is about 40%. In view of this, scientists had predicted that this characteristic had recently appeared in the history of mankind, as people dispersed into Eurasia. (A person who lived in the Philippines almost 50,000 years ago had such a tooth.)

Yet, the discovery indicates that humans may have inherited the function of Denisovans ancestors. "His presence in an archaic 160,000-year-old human in Asia strongly suggests that the trait was transferred to H. sapiens in the region by a miscegenation with archaic humans in Asia," said the author of the book. 39; Shara Bailey study, anthropologist at the University of New York. A declaration.

This study does not provide direct genetic evidence for hybridization; scientists were able to extract old proteins, but not DNA, mandible. But functionality is a strong sign of miscegenation, the scientists said. "We now have very clear evidence that gene flow between archaic and H. sapiens groups has resulted in the transfer of identifiable morphological characteristics," they wrote in the new study.

Denisovans were identified for the first time in 2010 as a species based on a finger bone found in Siberia. Subsequent genetic tests showed that they mated to Homo sapiens, as well as to Neanderthals. As my colleague Sarah Kaplan wrote last year, some scientists compare the planet in prehistoric times to that of JRR Earth in Tolkien's midst: "Aside from hobbits, dwarves and elves, there were different types of humans. "

– Ben Guarino

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