New Type of Ancient Human Found—Descendants Live Today?

The Max Planck folks are about the best around for analyzing ancient DNA, but I would love to see a couple of additional specimens sequenced and see if the results match.This finding, if confirmed, would add support to the multiregional theory.

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The multiregional hypothesis seems to be incorrect for the west, Africa and Europe, but I wonder if these findings may not support it for eastern Asia. I have always wondered about some line traits from Asian erectus that seem to persist into modern Asian groups. The finding that there was an additional, previously unknown species in east Asia and that it has some living descendants just adds to the problem--and the question of just how much interbreeding was going on that has not previously been recognized.From the article:

On the basis of the new findings, the scientists propose that the ancestors of Neanderthals and Denisovans emerged from Africa half a million years ago. The Neanderthals spread westward, settling in the Near East and Europe. The Denisovans headed east. Some 50,000 years ago, they interbred with humans expanding from Africa along the coast of South Asia, bequeathing some of their DNA to them. ...

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The Massachusetts scientists concluded that the finger bone belonged to a hominin branch that split from the ancestors of Neanderthals roughly 400,000 years ago. Dr. Paabo and his colleagues have named this lineage the Denisovans. ...

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Next, the researchers looked for evidence of interbreeding. Nick Patterson, a Broad Institute geneticist, compared the Denisovan genome to the complete genomes of five people, from South Africa, Nigeria, China, France and Papua New Guinea. To his astonishment, a sizable chunk of the Denisova genome resembled parts of the New Guinea DNA.

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The correct reaction when you get a surprising result is, ‘What am I doing wrong?’ said Dr. Patterson. To see if the result was an error, he and his colleagues sequenced the genomes of seven more people, including another individual from New Guinea and one from the neighboring island of Bougainville. But even in the new analysis, the Denisovan DNA still turned up in the New Guinea and Bougainville genomes.

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Given the DNA showing up in New Guinea and Bougainville, there does seem to have been interbreeding. Now the question is among whom, and how much?But given the persistence of this new DNA in Asia from 400,000 or 500,000 years ago to modern humans, there seems to be some support for the multiregion hypothesis in eastern or southeastern Asia.Add:From another article:

Paabo says the DNA they already have does indicate that this Siberian stranger, along with humans and Neanderthals, evolved from some common ancestor that lived in Africa about a million years ago. "Whoever carried this mitochondrial genome out of Africa about a million years ago is some new creature that has not been on our radar screens so far," he says.

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Scientists know generally when this new hominid as human ancestors are known appeared on the scene by comparing the number of mutations in the DNA of humans, Neanderthals and the X-woman. Mutations occur in a population at a certain rate that can indicate how long they've evolved separately from a common ancestor.

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Though Paabo can't say if this was an unknown species on the human line, he can say the X-woman's ancestors probably migrated from Africa a million years ago, well before modern humans evolved.

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Edited by Coyote, : Added informationEdited by Coyote, : Add link

I haven't kept up with the really technical details since grad school.My bet though is that there was some continuity in Asia, and it most likely took the form of interbreeding.Modern humans certainly took over pretty well when they arrived, but I think they swamped out some of the earlier groups through interbreeding, rather than elimination and replacement.This most recent DNA evidence seems to suggest that.But I'd like to see it confirmed with a couple of additional sequences before I bet the rent money on it.

Good post.I've been avoiding this thread because it has become too pedantic.When I studied evolution/fossil man for my Ph.D. exams, I was taught the multi-regional hypothesis. This was some xxxxxx [censored] decades ago.Since then the Out of Africa hypothesis has come to dominate. But there are still some bits of the multi-regional hypothesis which seem to be accurate--those are the same ones that led to that hypothesis in the first place. Overall, it was incorrect, but those some bits remain.Ones I remember from grad school are primarily from Asia, and include such traits as shovel-shaped incisors. These traits, called line traits, show continuity from early populations, such as Home erectus, to modern humans.So whatever model you come up with, obviously some form of OoA, you will need to account for the persistence of a few line traits in eastern Asia.

One factor I don't recall seeing in the above posts which may help to account for the high rate of gene flow from Africa is culture and technology.With a more advanced culture and better technology than among those folks on the peripheries, the folks moving out of Africa could probably have supported larger populations. This would have enhanced their gene flow.I did a dissertation which included this type of approach, although not dealing with the early hominids vs. modern humans.The problem with this is that technology can spread from one group to another, helping to eliminate the disparity. But to the degree that the brains were different between the folks moving from Africa and the older groups in the peripheries, they may not have been able to adopt some of the culture and technology of the incoming out of Africa folks.This general theme was explored in the Clan of the Cave Bear series, where Neanderthals were portrayed as being unable to quickly adopt new ideas. Though fiction, this illustrates one very real possibility by which the OoA folks could have had an advantage as they spread and absorbed earlier populations.

Ancient Denisovans and the human family tree Good article. Read it here.

Hi--It is interesting indeed.My guess is that there was a lot more interbreeding than we thought.These different species represent geographic/temporal isolates, but that pertains to the fossils we have, and to the central tendencies of each of the species. Who knows how much fraternization there was at the fringes of each groups' ranges.That's some of the fun part of paleontology!