This article (2009) seems relevant to the discussion:
Humans may have hunted Neanderthals into extinciton.
FWIW, there is a long-standing theory in anthropological circles that basically proposes that we systematically eradicated all of the other "human" primates. The more plausible theory is that we had an ridiculously advanced ability to create novel tools (that is our hallmark as a species, after all) and the other groups just couldn't compete for resources.