[Ada Coddington]

I don't know what Neanderthal ladies looked like, but it probably would be more likely that Neandethal guys impregnated Cro-Magnon women than the other way around.

If so, the Cro-Magnon women might have had trouble getting their large-headed offspring down the birth canal.

[blam]

"If so, the Cro-Magnon women might have had trouble getting their large-headed offspring down the birth canal."

Good point. Of all the primates, humans are the only ones that birth with the childs head facing to the rear (of the mother) to accommodate the large head. This feature makes it difficult for the human mother to assist in the delivery of her child, unlike other primate mothers.