A jawbone found on the ocean floor near Taiwan provides evidence that the Denisovans — a poorly understood ancestor to modern humans — occupied southeast Asia 100,000 years ago. DNA extracted and analyzed from it has evolutionary implications, because, while contemporary southeast Asians have bits of Denisovan DNA in their genomes, the nearest known Denisovan fossil find, until now, hailed from northeastern Asia, according to a report in the journal Science.
“Modern human populations in eastern Asia, particularly in the southeast, have genomic elements derived from the Denisovans, and it has been suggested that the two interbred in the region,” according to a press release. “However, so far, the molecularly identified Denisovan fossils are very fragmentary and have been found only from two sites in northern Asia. This research has directly demonstrated that Denisovans were also distributed in southeastern Asia.”
Finding Traces of Denisovans
Denisovans are a fairly recent addition to the human genetic family tree. In 1980, a Buddhist monk discovered a curious jawbone — but it was stored and remained unanalyzed until 2010. That year, similar fossils found in Siberia’s Denisova Cave linked the two sites. Other fossils in the cave ranging from from 300,000 years to 100,000 years ago, suggested that different groups of early humans both used the cave and may have interacted.
These findings changed the way paleontologists thought about human evolution. Previously, the conventional wisdom was that we are direct descendants of Neanderthals out of Africa. Adding Denisovans to our ancestors’ genetic heritage creates a more complex story.
Read More: Who Were the Denisovans?
Evidence of Interbreeding
Other work suggests that Neanderthals and Denisovans likely interbred near the end of the Ice Age, when glaciers began their retreat and once frozen land became forested. Those conditions meant both species no longer were isolated by ice.
The newest study expands on that story, showing that the Denisovans weren’t limited to Tibet and Siberia. It also expands on the notion that Denisovans were sufficiently different than Neanderthals in two ways. First, analysis of the Taiwan jawbone, which they named Penghu 1, after the strait in which it was found — revealed proteins rare in contemporary humans, but common in known Denisovans. The Taiwanese teeth, like the Tibetan ones share a similar distinct root structure as well as large molars.
“The molecular identification of Penghu 1, a Denisovan, has significant implications for human evolutionary history in eastern Asia,” the press release concluded.
Read More: Did Early Humans Interbreed? These Scientists Made a Map to Prove It
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Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
