I agree with everything except your proposal that they have not disappeared. That is only partially true. Some of their DNA survives in some humans, but its not much. 4 to 6 % is the most I have heard of. To say that their species has not died out but just mixed with ours based on that.. its a stretch.

Their was some interbreeding which isnt suprising, but they were still basically wiped out by our line of humans. The only question is: exactly what gave us the advantage? What exactly was it? Better organization, language, weapons? Did we bring them plagues as we did the north american natives? Was it that we could survive on less calories? Were we just plain more aggressive? A cultural difference, rather than a genetic advantage?

God, this is terrible science writing … circa National Geographic from 1961.

More and more I tire of the assumption that Neanderthals were mindless animal like carnivorous buffoons. Their “disappearance” should be no more a mystery than the disappearance of the Algonquin indians. Further, there is nothing to suggest that half of what we know about modern humans of Europe did not come from or was not adopted from Neanderthals. The record(s) are only now beginning to show that they ate more than meat and that modern Europeans carry part of the Neanderthal genes. Interbreeding is almost guaranteed and to assume it didn’t happens seems ridiculous.

The questions science should be asking is why there is not yet evidence that they were as accomplished at survival as our ancestors? It’s starting to look a lot like we are the descendants of the Neanderthals, and that they really did not disappear. Evolution did not select them, but their mix breed offspring may well be what we see wandering Europe today. I think the mystery is not why they disappeared, but why it appears that they did. The assumption of their demise seems premature.