Mystery human species unearthed from genome map of early humans?
|November 20, 2013||Posted by News under Human evolution, News, speciation|
Recently, I noted a new study on early human dentition which suggested that no known hominin is a common ancestor of Neanderthals and modern humans. Now, a find making waves is that the Denisovan genome suggests a “mysterious archaic population,” a “mystery human species” was once afoot—and in bed with everybody:
“Mysterious archaic population”:
The new Denisovan genome indicates that this enigmatic population got around: Reich said at the meeting that they interbred with Neanderthals and with the ancestors of human populations that now live in China and other parts of East Asia, in addition to Oceanic populations, as his team previously reported. Most surprisingly, Reich said, the new genomes indicate that Denisovans interbred with another extinct population of archaic humans that lived in Asia more than 30,000 years ago, which is neither human nor Neanderthal.
The meeting was abuzz with conjecture about the identity of this potentially new population of humans. “We don’t have the faintest idea,” says Chris Stringer, a paleoanthropologist at the London Natural History Museum, who was not involved in the work. He speculates that the population could be related to Homo heidelbergensis, a species that left Africa around half a million years ago and later gave rise to Neanderthals in Europe. “Perhaps it lived on in Asia as well,” Stringer says. (Nature)
Despite such evident fertility, this is supposed to be a separate species.
“Mystery human species”:
The genome shows that Denisovans were cousins of the Neanderthals – this much was already known. Their lineage branched off from ours around 400,000 years ago, before splitting into the Neanderthals and Denisovans.
That should mean that Denisovans and Neanderthals look equally different from modern humans, but on closer inspection, Reich found that that wasn’t the case. “Denisovans appear more distinct from modern humans than Neanderthals,” he told the meeting. Specifically, scattered fragments amounting to 1 per cent of the Denisovan genome look much older than the rest of it.
The best explanation is that the Denisovans interbred with an unidentified species, and picked up some of their DNA. Or as Reich puts it: “Denisovans harbour ancestry from an unknown archaic population, unrelated to Neanderthals.” (New Scientist)
“Species” interbreeding as readily as this? Conveniently, there are many definitions of “species” so the term can be flung around with abandon, provided one has the right credentials.
New Scientist riffs, “The story of human evolution just got even more bizarre.” True, but one wonders whether they see that there is more than one way to interpret that statement. In any event, no illustrations of the mystery species are available; National Geographic hasn’t picked up on the story yet.
One evident fact emerges from all this: True reason why the species is mysterious. Child support laws had, um, teeth back then. “Mr. Mysterious” had to stay mysterious (to say nothing of remote) if he knew what was good for his hide. – O’Leary for News