This is what I thought when was evoked cannibalism: what if those were the traces of sapiens festing of neanderthalis (and not neanderthalis eating neanderthalis, as seems to be supposed in the text)?
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).
As far as I understand Neanderthal genes in Humans don't actually exist in the Y chromosome.
That means that only female Neanderthals transmitted their genes down the Sapiens gene tree. This could mean all sort of things.
Maybe Neanderthal Males with Female Humans didn't generate viable off-spring. Maybe Our selection process favored non-Neanderthal genes and it was phased out of the Y chromosome gene pool? Maybe as you said Sapiens have a much darker past?
>only female Neanderthals transmitted their genes down the Sapiens gene tree
That would be right if the only genes a man passes to his children are on the Y chromosome, but a man passes 23 chromosomes to every one of his children. (One of those 23 will be either an X or a Y.)
Given how human babies are already at the maximum size a human female can deliver, I suspect you may be on to something. Other species don't have such traumatic births, but human babies barely fit through the birth canal. Neanderthal babies were probably much larger. In particular, their skulls. If a Neanderthal male impregnated a human female, I wouldn't be surprised if it killed her. Conversely, a Neanderthal female probably had an easier time delivering a hybrid baby.
My thoughts too. Something/someone ate these corpses using tools. Also, is there some proof that it is a usual thing? Because modern humans in particular circumstances can do cannibalism too. So it seems that there are a lot of extrapolations there.
Another point seemed to me a bit far fetched: that due to anatomy Neanderthals could not speak. But there are birds that imitate pretty well human speech.
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).