And since 2011 anthropologists have concluded that the two species did, indeed, meet and interact and either with or without consensus, shared genes. Yes, many of us have DNA that includes some Neanderthal.
But I found Golding's picture of how the two met to be actually dull. Maybe because he was writing long before modern research into our genes could influence his story.

I haven’t read Golding since Lord of the Flies, but picked this up because Penelopy Lively (Moon Tiger) said it was one of her favorites in a recent “The Week” article. Apparently, it was one of Golding’s favorites too. It’s a slightly disconcerting story of the meeting between a band of Neanderthals and Homo sapiens. For more than half the book we live the mundane, somewhat narrow-viewed lives of the Neanderthals Lok, Oa, etc. Narrow-viewed, yes…they are a loss as to what to do when their crossing log disappears from the river, however, they communicate telepathically through pictures of past events that they form in their minds. Then a band of homo sapiens comes along. Very interesting ending. Writing is not the most thrilling prose style ever but it will do…it’s the ending that makes you think…hmm, are there Neanderthals among us?