My work on mtDNA has led to a thesis that human life begins in Africa, spreads to Asia, and then spreads (1) back West to Europe and Africa and (2) further East into East Asia and the Pacific. I call this the Migration-Back Hypothesis, and you can read all about it here [1], and here, and on my blog generally, where you’ll find a ton of material on topic.

One of the most interesting observations in my work is that the living modern day people of Cameroon test as having the most ancient mtDNA in the dataset I’ve assembled, which contains 19 complete archaic mtDNA genomes, that are Heidelbergensis, Neanderthal, and Denisovan. This is not too shocking, considering that 53.01% of the 664 genomes in the dataset are at least a 60% match, to at least one archaic genome. This comparison to the archaic genomes is done using the only sensible global alignment, so you can’t argue that it’s chance, or cherry picking, there are a lot of living people that have archaic mtDNA.

The reason I’m writing this note is because I think one of the Neanderthal genomes was misclassified by the scientists that sequenced the genome. Specifically, this genome (row 389 in my dataset) has conflicting labels, with the “organism” field labelled as “Homo sapiens neanderthalensis”, whereas the “isolate” field, and the genome title refer to “Denisovan 17”. What I can find so far online, suggests that “Denisovan 17” is one of the Denisovan individuals that were found in the Denisovan Cave in Siberia. It is not entirely clear from the genome’s provenance on the NIH website, but that seems to be the better bet, especially given that the literature seems to treat Neanderthals as a type of Denisovan, which I don’t think is correct, but that doesn’t matter right now, there are all kinds of problems with science at the moment, which will take decades to correct.

Just applying a whole-genome test to this particular Neanderthal genome, it is a match to only one other Neanderthal genome (row 390 in my dataset), with 10,514 bases matching. Just for context, I noted previously, that the Neanderthal genomes are decidedly heterogenous, suggesting they were a race of people, not a homogeneous subspecies. These two Neanderthal genomes are both a match to the same Siberian Denisovan genome (row 377 in my dataset), with match counts of 8,915 and 8,588 bases. Now, that alone would suggest that some of the Neanderthals descend from some of the Siberian Denisovans, which is on its own very interesting, and consistent with my work.

However, the real catch, is that the potentially mislabelled Neanderthal genome (row 389 in my dataset, and one of the two discussed above) is a 98.48% match to a Cameroon genome (row 591 in my dataset), that itself is clearly of Denisovan origin. As noted above, the living people of Cameroon, test as the most ancient people in the dataset, including archaic genomes, suggesting they really are the living relatives of the first human beings. They are also clearly of Denisovan origin. On net, this is all consistent with Denisovans being the first humans in Africa, that then migrated to Asia, providing a 98.48% match between a living African and a Siberian Denisovan. Further, there are exactly 8 genomes in my dataset that are at least a 90% match to row 389 (i.e., the presumably mislabelled Neanderthal that seems to be a Siberian Denisovan), 6 are from Cameroon, 1 is Nigerian, and one is an Ancient Khoisan, plainly suggesting an African origin for this presumably Siberian genome.

All of this is plainly consistent with my Migration-Back Hypothesis, and of course, the Out of Africa Hypothesis.