Why did the Neanderthals die out? This is one of the biggest mysteries of human evolution.
These were people who flourished in Europe and the Near East for more than 100,000 years, yet vanished from their last stronghold in Europe about 30,000 years ago — at roughly the same time that modern humans arrived.
What happened to them? Or more to the point, what did we do to them?
This question has been asked for at least a century and every decade brings a different answer. Until at least the 1960s, the solution to the mystery seemed obvious: Neanderthals just weren't smart enough.
They were low-browed cavemen, a near-miss in evolution's attempt to create intelligent life.
They couldn't speak, their hands were incapable of fine motor skills — they couldn't even stand up straight.
Our ancestors probably wiped them out without breaking a sweat.
As appealingly straightforward as that notion might have been, it hasn't stood the test of time.
The truth is, Neanderthals could stand up straight (the one skeleton that gave rise to the myth had been deformed by serious arthritis), recent research shows that their hands were every bit as articulate as ours, their brains were bigger than ours and they prospered — for a very long time — in an ice-age landscape. Yet they did die out.
The latest investigation into this mystery has, unfortunately, only clouded the picture.
Anthropologists Donald Grayson and Françoise Delpech have examined the bones of reindeer, horses, wild goats, pigs and even rhinoceroses left behind by people who occupied a cave in southern France.
The amazing thing about this cave is that it was a dining room for at least 50,000 years — first for Neanderthals, then modern people.
Grayson and Delpech examined the bones for any signs that might explain why the Neanderthals failed but modern people thrived.
Did our ancestors succeed in killing a wider variety of animals? Were they more efficient butchers? Could the bones reveal that they had more efficient tools?
The answer in every case was "no."
There were no discernible differences in the types of prey, the numbers or the way they were butchered.
The Neanderthals seemed to be just as good at hunting as the people who succeeded them.
The one difference the anthropologists did turn up was that the number of cave bears seemed to decline rapidly right around the time that modern people came on the scene.
However, it looks as if this had more to do with the increasing numbers of modern humans than their hunting prowess — they may have simply displaced cave bears from their lairs.
So, at least in this particular cave, the arrival of modern humans gives us no clues as to why they came out on top.
Admittedly, it is only one cave, one extremely narrow slice of Paleolithic life, but it does suggest that whatever extinguished the Neanderthals isn't going to be easy to identify.
It is true that the Neanderthals left behind fewer traces of high intelligence: They did not build lasting structures of any kind, their tool kit remained largely unchanged over millennia and they apparently never crafted enduring pieces of art.
Ironically, it might be the lack of art, rather than the unsophisticated tools and weapons, that is the strongest clue to their demise.
If art signals the presence of creativity and inventiveness, and perhaps even sophistication of communication, it might enhance survival in the face of rapidly changing conditions.
One of the things both Neanderthals and Homo sapiens had to cope with some 50,000 years ago was climatic change.
It would be an irony if cooling temperatures did in the Neanderthals — after all, they had colonized Europe during the ice ages.
Nonetheless, some anthropologists suggest they might finally have been extinguished by a deadly combination of dramatic environmental change and an inability to adapt to it.
If that is true, then our ancestors didn't kill off the Neanderthals — they simply stepped in to occupy a vacant stage.
What an irony that would have been: the lightly built recent arrivals from Africa taking over from the stocky, cold-adapted people that had reigned supreme in Europe for almost 100,000 years.
But brains, not brawn, won out.