Some people trace majority of their ancestry to neanderthals

[Prisoner Of Ice]

http://dienekes.blogspot.com/2014/01...rn-humans.html

From this paper, this should be of interest for those who argue if they are .1 or .2% more/less Neandertal than others based on commercial testing results:

Fourth, the standard deviation in Neanderthal ancestry among individuals from within the same population is 0.06–0.10%, in line with theoretical expectation (Supplementary Information section 3), showing that Neanderthal ancestry calculators that estimate differences on the order of a per cent18 are largely inferring statistical noise.

Also of interest, showing that while overall Neandertal ancestry in Eurasians is low (1+%), this average includes region where it is much higher, and indeed the majority:

The Neanderthal introgression map reveals locations where Neanderthal ancestry is inferred to be as high as 62% in east-Asian and 64% in European populations (Fig. 1b and Extended Data Fig. 2).

Finally:

We have shown that interbreeding of Neanderthals and modern humans introduced alleles onto the modern human genetic background that were not tolerated, which probably resulted in part from their contributing to male hybrid sterility. The resulting reduction in Neanderthal ancestry was quantitatively large: in the fifth of the genome with highest B, Neanderthal ancestry is 1.5460.15 times the genomewide average (Extended Data Table 4 and Supplementary Information section 9)22. If we assume that this subset of the genome was unaffected by selection, this implies that the proportion of Neanderthal ancestry shortly after introgression must have been >3%rather than the approximately 2% seen today.

One of the lingering questions about Neandertal admixture is why there are no Neandertal Y-chromosomes or mtDNA in modern Eurasians. The disappearance of Neandertal mtDNA seems unlikely according to one study, but might be explained if negative selection was at play.

A different question is whether hybrid sterility was actually noticed by modern humans/Neandertals during the period of admixture. Modern societies have historically frowned upon mixture between diverged sapiens populations, even though there is no evidence that the offspring of, say, an African and a European are biologically disadvantaged. But, in the case of sapiens-Neandertal crossings, the offspring would have been biologically disadvantaged, a fact that may have been noticed over the span of a few generations.

Regardless of the historical dynamics of the admixture process, some of the Neandertal genome proved itself useful in its new sapiens hosts, and while the process may have been painful for the people involved, evolution found a way to use at least some of the material introduced to our species by our Neandertal cousins.

Nature (2014) doi:10.1038/nature12961

The genomic landscape of Neanderthal ancestry in present-day humans

Sriram Sankararaman

Genomic studies have shown that Neanderthals interbred with modern humans, and that non-Africans today are the products of this mixture1, 2. The antiquity of Neanderthal gene flow into modern humans means that genomic regions that derive from Neanderthals in any one human today are usually less than a hundred kilobases in size. However, Neanderthal haplotypes are also distinctive enough that several studies have been able to detect Neanderthal ancestry at specific loci1, 3, 4, 5, 6, 7, 8. We systematically infer Neanderthal haplotypes in the genomes of 1,004 present-day humans9. Regions that harbour a high frequency of Neanderthal alleles are enriched for genes affecting keratin filaments, suggesting that Neanderthal alleles may have helped modern humans to adapt to non-African environments. We identify multiple Neanderthal-derived alleles that confer risk for disease, suggesting that Neanderthal alleles continue to shape human biology. An unexpected finding is that regions with reduced Neanderthal ancestry are enriched in genes, implying selection to remove genetic material derived from Neanderthals. Genes that are more highly expressed in testes than in any other tissue are especially reduced in Neanderthal ancestry, and there is an approximately fivefold reduction of Neanderthal ancestry on the X chromosome, which is known from studies of diverse species to be especially dense in male hybrid sterility genes10, 11, 12. These results suggest that part of the explanation for genomic regions of reduced Neanderthal ancestry is Neanderthal alleles that caused decreased fertility in males when moved to a modern human genetic background.

Over 60% for some asians and europeans.

I guess this highlights finally the concept that the % of neanderthal specific DNA is not the same as your percentage of ancestry, since vast majority of DNA betwen thals and others is shared.

Also looks like some neanderthal genes are selected against, and some selected on. Which could explain why there is (so far) no one with neanderthal y-dna or mtdna.

[portusaus]

Interesting. I've recently imagined this to be the case; as when comparing my phenotype to depictions of Neanderthals, I see basically the same distinct features to a lesser extent.

[Prisoner Of Ice]

It's interesting to me that this calculation has never been done. I do think more and more it's because of political reasons, especially when the results are this AMAZINGLY DRAMATIC.

But it does make sense and I'll describe the logic.

The highest known total genome % of neanderthal traits for someone is around 8%. What I didn't know before is how much difference there is for a full neanderthal, but obviously it's got to be around 12% (thought it was around 10%).

So for someone to maintain 8% they have to have about 2/3 of their ancestry come from neanderthals. Make sense? Because the FULL neanderthal only had 12% or so difference to start with!

So you actually have to multiply each percentage point by about 8%.

So if your genome has 3% neanderthal specific genes, your neanderthal ancestry is at least 24%.

[Jackson]

Interesting, surprising.

[Anglojew]

The Neanderthal introgression map reveals locations where Neanderthal ancestry is inferred to be as high as 62% in east-Asian and 64% in European populations

Is my reading correct that this was one guy in Utah and one guy in China?

[Jackson]

Interesting. I've recently imagined this to be the case; as when comparing my phenotype to depictions of Neanderthals, I see basically the same distinct features to a lesser extent.

Similar here, (although much more with my Dad, by a long shot), we both have very big deep rooted teeth too, that have caused problems at dentists. My roots were too long for an X-ray, which caused a little problem, and my Dad had to have 2 appointments to remove one tooth, lol.

[Insuperable]

It's interesting to me that this calculation has never been done. I do think more and more it's because of political reasons, especially when the results are this AMAZINGLY DRAMATIC.

But it does make sense and I'll describe the logic.

The highest known total genome % of neanderthal traits for someone is around 8%. What I didn't know before is how much difference there is for a full neanderthal, but obviously it's got to be around 12% (thought it was around 10%).

So for someone to maintain 8% they have to have about 2/3 of their ancestry come from neanderthals. Make sense? Because the FULL neanderthal only had 12% or so difference to start with!


So you actually have to multiply each percentage point by about 8%.

So if your genome has 3% neanderthal specific genes, your neanderthal ancestry is at least 24%.

Where wre you getting this from?

[Prisoner Of Ice]

Is my reading correct that this was one guy in Utah and one guy in China?

I think that's the case, those are the two highest samples in the human genome project. There might be even higher ones elsewhere, considering how small the sample size is. But that seems a lot higher than I expected (I was thinking 20-30% max). Pretty amazing.

[Prisoner Of Ice]

Where wre you getting this from?

The Neanderthal introgression map reveals locations where Neanderthal ancestry is inferred to be as high as 62% in east-Asian and 64% in European populations (Fig. 1b and Extended Data Fig. 2).

I don't know what else it could mean.

[portusaus]

Similar here, (although much more with my Dad, by a long shot), we both have very big deep rooted teeth too, that have caused problems at dentists. My roots were too long for an X-ray, which caused a little problem, and my Dad had to have 2 appointments to remove one tooth, lol.

Yep, I have teeth like that too. I just had a cleaning today, and the lady who performed it remarked at how I have large gaps between my teeth at the base (but not at the top, they are aligned).