[archi42]

I agree, lots of possibilities there, making the "widespread cannibalism" theory indeed pretty weak overall: It's quite possible that neanderthals only reverted to cannibalism in times of severe famines - which are not that unlikely to happen regularly over these huge time span. And I think that would still hold for modern humans (I think some air plane crash survivors did that).

Or maybe there was some cult/religion/tradition that demanded that specific enemies (or relatives) shall be eaten to harvest their "power". Again, some of our contemporary, modern humans still did that until quite recent (IIRC there was something with brains on HN recently, and how those who ate them [primarily that societies women] contracted brain diseases from their dead).