I think it's a bit of circular reasoning - Sapiens survived contact, Homo's niche is being the intelligent adaptive species, thus Neanderthalensis must have bee

I think it's a bit of circular reasoning - Sapiens survived contact, Homo's niche is being the intelligent adaptive species, thus Neanderthalensis must have been less intelligent and/or adaptive. Personally, based on the people I know with unusually many neanderthal alleles, I would guess the advantage had more to do with the size of tribes than the intelligence of individuals.