One theory that has become popular is that rh negative blood might come from the Neanderthals.
But were the Neanderthals in fact rh negative and has that theory ever been met with direct evidence?
I have personally contacted Svante Pääbo from the Max Planck Institute and asked him if they knew what the rh factor of the Neanderthal specimens examined was.
Here is the email I have received:
The Denisova and Altai Neandertal are homozygous for the ancestral “A” variant at position 25629943 on chromosome 1 that determines rhesus type in modern humans. This variant means that both are likely rhesus positive.
My follow up question was:
Could it be possible that that the Denisova and Altai Neanderthals
were homozygenous for the D negative gene rather than D positive?
No. As far as I can tell from the informative position that determines
rhesus type in humans, both are homozygous rhesus positive.
Note: Homozygous rhesus positive means that neither of the two specimens examined carried the rh negative gene recessively either making them both +/+.