[LRS]

The disease factor is the item I favor with my non expert opinion. So many animals of the Pleistocene disappeared, that that to me, I have to speculate that the Neanderthals succumb to the catastrophe as well. Something in the genetic makeup made them more vulnerable than the Cro Magnums that replaced them...

[wendy1946]

The Basic Non Evolution of Modern Man. The fact that we are not related to hominids other than possibly by similar design parameters, and that there is nothing on this planet which we could be descended from by any process resembling evolution.

[Savage Beast]

"The disease factor is the item I favor"

That makes sense. It was certainly important in the killing of many American Indians. It seems likely that infectious diseases to which they had no resistance swept through North America after the arrival of Columbus, destroying entire tribes and leaving survivors lost and vulnerable.

[muawiyah]

Here's a different approach. Let's say the Neanderthals had some tricks we don't know about and were so successful in their environment that the Cro-Magnons simply couldn't move into Europe until the Neanderthals up and died out suddenly.

One trick could have been use of vocalizations that controlled the game animals. Let's say that when they got hungry they popped in one of those nose whistles of theirs, blew it, and animals fell stunned at their feet.