Neanderthal admixture in humans!

[Heresson]

http://www.sciencemag.org/special/neandertal/

cute brute!

[Ecthy]

A bit OT I think this may point to other possible admixture in humans. I'm betting we will see some advanced erectus or other hominid admixture elsewhere in Asia in addition to the 4% N. that nonAfricans in general have.

I knew this wouldn't take long.

[One_more_turn]

Since humans will even fvck chimps, dogs, and goats, I find it hard to believe that they didn't fvck Neanderthals.

[Heraclitus]

If this is true it will severely hurt my faith. Serious post.

I guess you can belive in God nd think that he guided evolution to create Homo Sapiens Sapiens, but if some humans mated with other now extinct hominids and transmited their genes, how can you still believe in God?

I don't know how to break this to you but... you do realize there is evidence that a few genes crossed over between humans and chimpanzee lineages as late as 1,5 million years ago right?

[Heraclitus]

I knew this wouldn't take long.

What? Admixture happened with Neanderthals. They weren't the only Humans in Eurasia at the time, why so dismissive that other mixing happened? Multi regionalism lite seeems to have been brought back to life.


I hope they manage to get good genetic material out of Homo Floresiensis (aka Hobbits), it would be awesome to figure out once and for all what they are.

[Ben Kenobi]

There's 4 % crossover in our DNA with Neanderthals. Why can't this be explained by a couple of humans mating with Neanderthals and the offspring being brought up in Neanderthal families, leaving Homo Sapiens Neanderthal DNA-free?

Better question.

What if they had a progenitor? Wouldn't we see similar overlap?

[Heraclitus]

From the paper everyone here refuses to read.

Average DNA divergence between Neandertals and humans. To estimate the DNA sequence divergence per base pair between the genomes of Neandertals and the reference human genome sequence, we generated three-way alignments between the Neandertal, human, and chimpanzee genomes, filtering out genomic regions that may be duplicated in either humans or chimpanzees (SOM Text 10) and using an inferred genome sequence of the common ancestor of humans and chimpanzees as a reference (51) to avoid potential biases (39). We then counted the number of substitutions specific to the Neandertal, the human, and the chimpanzee genomes (Fig. 2). The overall number of substitutions unique to the Neandertal genome is about 30 times as high as on the human lineage. Because these are largely due to transitions resulting from deamination of cytosine residues in the Neandertal DNA, we restricted the divergence estimates to transversions. We then observed four to six times as many on the Neandertal as on the human lineage, probably due to sequencing errors in the low-coverage Neandertal DNA sequences. The numbers of transversions on the human lineage, as well as those on the lineage from the Neandertal-human ancestor to the chimpanzee, were used to estimate the average divergence between DNA sequences in Neandertals and present-day humans, as a fraction of the lineage from the human reference genome to the common ancestor of Neandertals, humans, and chimpanzees. For autosomes, this was 12.7% for each of the three bones analyzed. For the X chromosome, it was 11.9 to 12.4% (table S26). Assuming an average DNA divergence of 6.5 million years between the human and chimpanzee genomes (52), this results in a point estimate for the average divergence of Neandertal and modern human autosomal DNA sequences of 825,000 years. We caution that this is only a rough estimate because of the uncertainty about the time of divergence of humans and chimpanzees.

Five present-day human genomes. To put the divergence of the Neandertal genomes into perspective with regard to present-day humans, we sequenced the genomes of one San from Southern Africa, one Yoruba from West Africa, one Papua New Guinean, one Han Chinese, and one French from Western Europe to 4- to 6-fold coverage on the Illumina GAII platform (SOM Text 9). These sequences were aligned to the chimpanzee and human reference genomes and analyzed using a similar approach to that used for the Neandertal data. Autosomal DNA sequences of these individuals diverged 8.2 to 10.3% back along the lineage leading to the human reference genome, considerably less than the 12.7% seen in Neandertals (SOM Text 10). We note that the divergence estimate for the Yoruba individual to the human genome sequence is ~14% greater than previous estimates for an African American individual (56) and similarly greater than the heterozygosity measured in another Yoruba individual (33). This may be due to differences in the alignment and filtering procedures between this and previous studies (SOM Text 9 and 10). Nevertheless, the divergence of the Neandertal genome to the human reference genome is greater than for any of the present-day human genomes analyzed.

Distributions of DNA divergences to humans. To explore the variation of DNA sequence divergence across the genome, we analyzed the divergence of the Neandertals and the five humans to the reference human genome in 100 kilobase windows for which at least 50 informative transversions were observed. The majority of the Neandertal divergences overlap with those of the humans (Fig. 3), reflecting the fact that Neandertals fall inside the variation of present-day humans. However, the overall divergence is greater for the three Neandertal genomes. For example, their modes are around divergences of ~11%, whereas for the San the mode is ~9% and for the other present-day humans ~8%. For the Neandertals, 13% of windows have a divergence above 20%, whereas this is the case for 2.5% to 3.7% of windows in the current humans.



Fig. 3 Divergence of Neandertal and human genomes. Distributions of divergence from the human genome reference sequence among segments of 100 kb are shown for three Neandertals and the five present-day humans.

Furthermore, whereas in the French, Han, and Papuan individuals, 9.8%, 7.8%, and 5.9% of windows, respectively, show between 0% and 2% divergence to the human reference genome, in the San and the Yoruba this is the case for 1.7% and 3.7%, respectively. For the three Neandertals, 2.2 to 2.5% of windows show 0% to 2% divergence to the reference genome.



Four possible scenarios of genetic mixture involving Neandertals. Scenario 1 represents gene flow into Neandertal from other archaic hominins, here collectively referred to as Homo erectus. This would manifest itself as segments of the Neandertal genome with unexpectedly high divergence from present-day humans. Scenario 2 represents gene flow between late Neandertals and early modern humans in Europe and/or western Asia. We see no evidence of this because Neandertals are equally distantly related to all non-Africans. However, such gene flow may have taken place without leaving traces in the present-day gene pool. Scenario 3 represents gene flow between Neandertals and the ancestors of all non-Africans. This is the most parsimonious explanation of our observation. Although we detect gene flow only from Neandertals into modern humans, gene flow in the reverse direction may also have occurred. Scenario 4 represents old substructure in Africa that persisted from the origin of Neandertals until the ancestors of non-Africans left Africa. This scenario is also compatible with the current data.

Better question.

What if they had a progenitor? Wouldn't we see similar overlap?

Sigh. People on this forum know nothing about genetics.

Ben of course Homo N. and Homo Sapiens have a common progenitor. It may shock you but we and Chimpanzees have common ancestors, and probably all life on this planet has common progenitors.

People instead of speculating idly on their method, just read the godamn link I posted. Its a long paper but its worth it.

[Heraclitus]

Can someone set me straight here?

There's 4 % crossover in our DNA with Neanderthals. Why can't this be explained by a couple of humans mating with Neanderthals and the offspring being brought up in Neanderthal families, leaving Homo Sapiens Neanderthal DNA-free?

To put it another way, maybe they had some of our DNA, rather than us having some of theirs?

The question is answered in the paper. Read it.

[MrFun]

If this is true it will severely hurt my faith. Serious post.

I guess you can belive in God nd think that he guided evolution to create Homo Sapiens Sapiens, but if some humans mated with other now extinct hominids and transmited their genes, how can you still believe in God?

I'm a spiritual Christian but I do not believe in Creation.

[Heraclitus]

They are all humans. Neanderthals are not a separate species as they can and did interbreed with other humans. Yes, there are some anatomical differences, but there are differences of a similar scale between the pigmy tribes of Africa and Scandinavians and Chinese etc. As a single species, of course the DNA is very similar.
There are much greater differences between skulls of a pitbull terrier and a greyhound, but they can interbreed and we know they are the same species, dog, exactly the same situation with Neanderthrals and humans. Genocide has been committed in the past against the Neanderthral tribe, rather than admit genocide we seem to feel more comfortable naming them as a separate species.

They are humans but not Homo Sapiens Sapiens. Some consider them Homo Sapiens Neanderthalensis others consider them Homo Neanderthalensis. They are variously classified as either a seperate species or subspecies.

I'm not aware of anyone classifying existing humans into subspecies. Unless race is a euphemism for subspecies.





Yes there are variations in skull shape in Homo Sapiens Sapiens but...


Asian skull


European skull


African skull


Australian aboriginal skull


I hope everyone can agree that while racial differences are indeed apparent enough in Humans to tell remains apart we probably shouldn't go as far as to classify them as separate subspecies based on this alone.

Edit: The aboriginal skull does look odd though. Perhaps its atypical. I'll try to find another one.

Second Edit:



Google threw this out (Aboriginal vs. Slav)

Again the difference seems suspect. I'm not vouching for the source in any way, its just what I got after googling. Perhaps old Aboriginal skulls of individuals in good health are hard to come by?

[ricketyclik]

The question is answered in the paper. Read it.

OK, I get it now, thanks. On reflection I should have realised with the African/Non-African part anyway.

[ramseya]

Heraclitus:

The aboriginal skull can't possibly be right... There's no way the owner of that skull was a morphologically modern human.

Yet when I google aboriginal skulls, I keep getting similar images although some of them are mis-labelled and are actually neanderthal skulls and others are from white supremacist websites so I question the validity of these images.

[ramseya]

well I got this from Weston A. Price's "Nutrition and Physical Degeneration":



The bottom pane shows a comparison between an aboriginal skull and the dome of Peking Man (Homo Erectus).

Price writes:

I have previously referred to a report by Professor Weidenreich regarding the resemblance of the Australian native's skulls to those of the recently discovered Peking man in the caves of China. In Fig. 60 are two views for comparison. The skull at the left is that of an Australian primitive photographed in a museum in Sydney, and an outline of the Peking skull is shown at the right. Professor Weidenreich has emphasized the observations that when three skulls are put in series, namely, the Australian primitive, the Peking skull and a chimpanzee skull, the Peking skull appears to be about half way between the two in design and developmental order. The Australian primitive's skull is higher in the crown, showing much greater brain capacity. The supra-orbital depressions are less deep in the Peking than in the chimpanzee, and still less deep in the Australian primitive. The supra-orbital ridges which produce the prominent eyebrows are less pronounced in the Australian primitive than in the Peking man, and still more prominent in the chimpanzee.

Now it's not clear how old that aboriginal skull is. It could be from the first settlers to Australia or it could have been from a specimen that lived in the early 20th century. Price doesn't make that clear from skimming that chapter.

It looks a bit more modern than the skulls you posted but there's still an Occiptal bun though less prognathism, a less prominent ramus (I think ramus is the term for that part of the jaw), etc. Hmm... I wonder if these are just particular specimens or characteristic of the entire ethnic group.

[ramseya]

So I started to look at some Neanderthal reconstructions.





Come on, those guys could be straight from the local bar. They've really made neanderthals look more and more like us over the years!

[Traianvs]

Neanderthals and Sapiens didn't interbreed evar, ye noobs!