kingjohn
Regular Member
- Messages
- 2,228
- Reaction score
- 1,198
- Points
- 113
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature currently requires accessing the site using the built-in Safari browser.
A back to Africa hypothesis has been proposed in which humans from Eurasia returned to Africa and impacted a wide range of sub-Saharan populations (19). Our data shows that Neandertal signatures are present in all major African haplogroups thus confirming that the Back to Africa contribution to the modern mitochondrial African pool was extensive.
Am I reading this wrong or are a handful of those Neanderthals mtDNA haplo H1?
Also, the bank of mondern mtDNA from the phylotree database used to compare is woefully sparse. They chose H1a1, H3, H15, U1a1d, and U6a7a2 as the only H and U samples to compare when we have such a wide variety in Europe.
H1a1, H3, H15, and U6a7a2 (Not the U1a1d) had one of the Neanderthal-exclusive variants. Does this mean that H is older in Europe than we thought?
Since they only chose three H to test, we don't have a lot of info. I wish they would let us hobbyists replicate the calculations using all the other H and U versions.
View attachment 9284
Comparative analysis of the mitochondrial DNA from present day humans, ancient Homosapiens and Neandertals, 52 sequences of modern human mtDNA, representing all major mitochondrial haplogroups (table S1), were selected from the PhyloTREE database (25) and downloaded from GenBank. Six ancient H. sapiens mtDNA and eight Neandertal mtDNA sequences were downloaded from GenBank (tables S1-S3).
I only has a cursory look at the paper, but it seems that they did not find any Neanderthal mtDNA in any modern populations. They are comparing mutations found in Neanderthal mtDNA samples with mutations found in modern human haplogroups. If they are under the impression that they could have somehow be passed on by Neanderthal to Homo sapiens, then they should go back to school, as mtDNA does not recombine. I really don't see the point of comparing the presence of mutations between these populations.
Very interesting that they posit that Africans have more of this Neanderthal mtDna "intrusion" because that particular mating involved an AMH male with a Neanderthal female, whereas it was the other way around in Europe.
That was the far fetched claim I was referring to. They are suggesting a major revision to our understanding of mtDNA.
Analyses presented here suggest that Neandertal genomic signatures might have been a
product of rare mtDNA recombination events. Although there is evidence supporting mtDNA
recombination its weight in phylogenies remain controversial. Some authors contend that due to
its high mutation rate reverse compensatory mutations can be confounded with recombination in
mtDNA. Our data supports a mtDNA recombination scenario in which recombination events are
extremely rare thus producing a small number of Neandertal
signatures.
I only has a cursory look at the paper, but it seems that they did not find any Neanderthal mtDNA in any modern populations. They are comparing mutations found in Neanderthal mtDNA samples with mutations found in modern human haplogroups. If they are under the impression that they could have somehow be passed on by Neanderthal to Homo sapiens, then they should go back to school, as mtDNA does not recombine. I really don't see the point of comparing the presence of mutations between these populations.
If the split was 600,000 years there should be about 75 mutations differentiating the two lineages.that is what I taught
but what are the chances of the same mutations in mtDNA happening in both independant modern human and Neanderthal branches?
they claim there are only 918 polymorphic positions of the modern human/Neanderthal mtDNA
some of the data they present here must be wrong
From a quick search for papers on mtDna recombination:
This is sort of a summary:
http://www.nature.com/hdy/journal/v93/n4/full/6800572a.html
"Over the last 5 years, there has been considerable debate as to whether there is recombination in human mitochondrial DNA (mtDNA) (for references, see Piganeau and Eyre-Walker, 2004). That debate appears to have finally come to an end with the publication of some direct evidence of recombination. Schwartz and Vissing (2002), 2 years ago, presented the case of a 28-year-old man who had both maternal and paternally derived mtDNA in his muscle tissue – in all his other tissues he had only maternally derived mtDNA. It was the first time that paternal leakage and, consequently, heteroplasmy was observed in human mtDNA. In a recent paper, Kraytsberg et al (2004) take this observation one step further, and claim to show that there has been recombination between the maternal and paternal mtDNA in this individual.There is a major possibility, in experiments of this nature, that the recombinants have been produced in laboratory, either by PCR, or by some other mistake. However, the authors have gone to great lengths to ensure that the recombinants are genuine, including repeating the experiment with a mix of maternal and paternal mtDNAs. They did not observe any recombination in this latter experiment, so we can be very confident that recombinants that they detected in the muscle tissue are genuine.
Back to the case of Neanderthal mtDNA swapping genes with H. sapiens mtDNA, that would leave much more obvious traces as the two sets of mtDNA evolved for 600,000 years separately and would have accumulated a lot of diverging mutations. It's much easier to explain those shared mutations as coincidences due to chance mutations that were positively selected due to their beneficial effects in a similar environment (Western Europe in this case). It's all the more likely for the mutations they listed that fall in the hypervariable region (high mutation rate) such as 195, 16093, 16129, 16189 and especially 16183 and 16519, two positions that are so unstable they are known to vary between cells in a same individual, which is why they aren't even used in the mtDNA phylogeny.
This thread has been viewed 7861 times.