“Why are there no Neanderthal mtDNA haplogroups present in modern humans?”

This question keeps coming up. As Europeans have 2-4% Neanderthal DNA, the claims made make people wonder. The problem with the claim:

It is silly.

Here is why:

“Neanderthal mtDNA is very different from human mtDNA, so interbreeding did not happen.
=> FALSE : this is one of the stupidest argument I have read so far. First of all, Mitochondrial DNA is only transmitted by the mother. It is very possible that some haplogroups have disappeared with time, especially if they had pathogenic mutations. If Neanderthal mtDNA caused an evolutionary handicap compared to Homo Sapiens mtDNA, it would have been wiped out with a few hundreds or thousands years.

Take a family tree of cave person going back 5 generations. All of his 32 great-great-great-grand-parents are Homo Sapiens, except one Neanderthal woman. If the Neanderthal woman is not the ancestor in cognatic line (mother’s mother’s mother’s…), then the child will not inherit Neanderthal mtDNA, although he/she will inherit other genes from Neanderthal. After 5 generations there is only one chance out of 16 to inherit that particular female ancestor’s mtDNA. After 21 generations, there is only one chance out of 1 million. If that mtDNA is pathogenic, the chances are close to zero. Think about 1,000 generations that separate us from the “extinction” of pure Neanderthals.

Secondly, mtDNA evolves with time. Most of the haplogroups found in Europe nowadays did not exist 40,000 years ago, when Homo Sapiens reached Europe. If Neanderthal mtDNA had survived, it would have evolved just like Homo Sapiens mtDNA. If we found that mtDNA in someone, it would be quite difficult to recognise when compared to the few samples of Neanderthal bones (some over 100,000 years old !) tested. It could be that haplogroups such as X, W or I actually descend from Neanderthal, but have a high genetic distance to the bones tested because a) they do not belong to the same subspecies of Neanderthal, and b) they have evolved too much in 40,000 years. “

Source and more:

Do modern Europeans partly descend from Neanderthal ?

“Why is there no Neanderthal y-DNA in modern humans?”