Vendramini’s claim is totally simple and logical. Neanderthals kept their basic primate appearance (what you’d expect from their DNA being halfway between ours and that of chimpanzees); became total carnivores in the European ice age; developed the long dense fur coats which all ice age animals had and without which nothing would have lasted forty seconds in the European ice age; developed big eyes for nocturnal predation activity, explaining the eye sockets being twice the size of ours; lost the big canines of apes after they developed knives and cutting tools.
If, as is claimed, Neanderthals and humans could mate and produce fertile children than we are the same animal. All differences are superficial.