"The Neanderthal was a highly successful species,"' said Klein, but the reasons they became extinct are still unknown. Some theories have suggested they were wiped out by diseases introduced by modern humans. Another theory is that modern humans had better minds and an organized culture that enabled them to outsmart the Neanderthals for limited resources of game and other food.
"There is little to suggest that Neanderthals could behave in a modern ... way," Klein writes in Science. "This inability may explain why they disappeared so quickly and completely."
NYTimes March 06, 2003
{they never suggest what to many of us is the most obvious answer, genocide, murder, Cain and Abel, "the only good Indian is a dead Indian", that, those guys. that's what happened.}