[after dark]

I never thought of Neanderthal as an ancestor.

It is possible that Neanderthal could have mated with the unknown apelike ancestor and vice versa.

[HiTech RedNeck]

This would mean the races/species were close enough to be united into one. The number of chromosomes is different so any attempt would result in severely disabled offspring, if any.

[after dark]

This unknown apelike ancestor could have facilitated the transference of genetic material from humans to Neanderthals and the reverse.

I think most of the studies which have failed to show the presence of Neanderthal genes only look at mitochondrial DNA.

I also think they cast their net to far. They should only study populations living in the areas where Neanderthal coexisted with humanity, and places where Neanderthals were able to hold out the longest.