That's one theory.<quoted text>
From all recent accounts, the Neanderthals were just as intelligent and resourceful as their Homo Sapiens counterparts. Their biological structure, however, was more demanding of nutrition from the surrounding Ice Age environment and so they lost out.
You, on the other hand, have an extremely efficient biology.
You can live off of nothing but sh*t and be happy about it.
Another theory is they were not as mentally capable as Cro Magnum, and lost a global war for territory and died out.