Rgards, TQ.
I think that the biggest problem with analysis is that we don't know much about what circumstances existed in pre-history. Six different anthropologists will give you 10 different answers. They each have their own point of view, and sometimes their own particular agenda. I find each of the theories interesting, but I don't hold to any one theory.
The most interesting theory I've come across is the idea that many varieties of humans existed at the same time. The Cro-Magnon and the Neanderthal may have been different races rather than different species. The current homo sapiens may be a blending of those races, rather than the winner of the battle between the two.