From the detailed genomes of both Neandertals and Denisovans, Pääbo and Montgomery Slatkin of the University of California, Berkeley, estimated that 17% of the Denisovan DNA was from the local Neandertals. And the comparison revealed another surprise: Four percent of the Denisovan genome comes from yet another, more ancient, human —"something unknown," Pääbo reported. "Getting better coverage and more genomes, you can start to see the networks of interactions in a world long ago," says David Kingsley, an evolutionary biologist at Stanford University in Palo Alto, California.
Meanwhile, the article sheds light on two interesting contradictions in the Denisova data. The analysis of the high-coverage data last fall  noted that the pinky bone genome is consistent with a very small long-term effective size, because of its limited genetic variation ("Denisova at high coverage". These results included a "drastic decline in size" around the time the Denisovans were estimated to have separated their population from the ancestors of living sub-Saharan Africans.
That result was curious in comparison with the mtDNA evidence. The Denisovan mtDNA is substantially more divergent from living human and Neandertal mtDNA, with an estimated time for the last common ancestor of mtDNA among these groups a bit more than a million years ago.
Now, we may be learning that the Denisovan genome itself represents different ancestral groups -- not only a more ancient "something unknown" population, but substantially the local Neandertals. That kind of mixture is not the population history described by papers on the Denisova genome so far. And a third Denisovan mtDNA from one of the third molars at the site is substantially different from the other two, pointing to greater mtDNA diversity within the Denisovan population than now known from either Neandertals or living people.
Originally posted by Nacirema
reply to post by punkinworks10
"7% of the Denisovan DNA was from the local Neandertals."
Is this due to interbreeding or a shared common ancestry?
Im starting to lean toward a very early exit from Africa by a pre erectus ancestor, such austrolopithicus, that evolved into what we know of as Asian erectus, that colonized most of the reachable world, and eventually became us.
This paper supports Meyer et al.’s (2012) conclusion that East Asians are closer to Neandertals than Europeans. The difference is estimated on the order of 40%. This makes it unlikely that the 1-4% similarity between non-African human and Neandertal genomes, to the exclusion of African human genomes, is product of admixture between Neandertals and expanding modern humans. If this was the case, Europeans would have been more heavily admixed than East Asians. The asymmetrical connection between an archaic hominin species and a modern human population is further found in the case of Denisovans, whose remains are geographically located in East Asia but who show greater similarity to modern Melanesians than to East Asians. Wall et al. (2013) report that they failed to find any traces of admixture between Denisovans and East Asians (contra Skoglund & Jacobsson 2011) but they sampled only Japanese and Han Chinese, while Skoglund & Jacobsson reported the highest frequencies of Denisova alleles outside of Melanesia, in Southeast Asia and America (see more here). For the archaic admixture hypothesis to hold, one would need to postulate the dilution of Neandertal alleles in Europe and Denisovan alleles in East Asia by the subsequent (e.g., Neolithic) gene flow of populations unadmixed with Neandertals and Denisovans into these regions. The only place where these populations could have originated is Africa, but there’s no evidence for an excess of African alleles in East Asians and Europeans compared with Melanesians. Hence, the genomic pattern of association between Neandertals, Denisovans and non-African humans may be better explained as common descent, with African humans derived from non-African humans. Wall et al. (2013, 21) found evidence that can be interpreted precisely to such an effect:
“Also, we find evidence for a small but significant amount of Neanderthal admixture into the Maasai genomes (p ~ 0.03, Table S4). When compared to the Yoruba, the Maasai have a higher average D than the Luhya (Figure 3b, Table S4). When the Maasai are compared to all other African samples the average D is positive (Figure 3d). In addition, when East Asians and Europeans are compared to the Maasai, the average D’s are somewhat lower than when they are compared to either the Yoruba or Luhya.”
Table S4 shows that all of Wall et al.’s African samples have a Neandertal component, with Yoruba and Luhya training slightly behind Maasai. The paucity of Neandertal and Denisovan alleles in such “Paleoafricans” as Khoisans is better explained as product of admixture with African archaics that diluted the original Eurasia-derived gene pool of Africans
Originally posted by rickymouse
Very interesting info.
It's strange that they say modern humans are only 40 thousand years old. If we have been blended with other races that were much older, I will refer to myself as being related to the oldest one just as much as the modern man one. Think about it, at one point one of your ancestors was pure neanderthal if you possess the neanderthal gene. That means your great great great, etc.... grandpa or grandma was a neanderthal. So I consider my ancestors to go back as far as Neanderthals do in time. If they were this Devonian, and it was a million years, than my bloodline is over a million years old. I think that my ancestors have been on this world for a long time if I consider what they are saying is true.