Sometime between 30,000 and 40,000 years ago, the Neanderthals abruptly disappeared after a run of perhaps 200 millennia in the Near East, west Asia and, most notably, in the ice age caves of Europe. On that score, there is no dispute.

How this happened, and why, is another matter. For years, paleontologists have argued about whether anatomically modern humans invading from the east either wiped out the Neanderthals or out-innovated them; or, alternatively, whether Neanderthals and the invaders simply interbred to create today's Homo sapiens. This debate has taken on new virulence amid an accumulation of new, but still inconclusive, evidence.

DNA analysis to date suggests that Neanderthals and modern humans are quite probably unrelated -- that Neanderthals were a distinct species altogether.

However, archaeologists have shown in the past few years that modern human remains thought to be associated with human-made artifacts from the late Neanderthal era actually date from much more recent times. No one has found modern human remains buried with artifacts older than perhaps 32,000 years.

The argument now is about whether Neanderthals were comic book characters -- not-quite-bright, club-carrying, knuckle-draggers who couldn't keep up with the invaders -- or, instead, simply a different people who somehow got sideswiped into extinction for some other reason.

This mystery, central to the study of human culture during the Stone Age, is nowhere near resolution. "A lot of this discussion is about how we see our own relationship to these creatures," said Princeton University anthropologist Alan E. Mann. "I worry these discussions are becoming much less about science."