[VadeRetro]

Anyway, "why did it branch?" It's always a tree. We used to depict the horse evolution as a straight line--we only had about three fossils--and that was wrong. When we got a lot more fossils, it was clear that the earlier depiction was wrong and some of the "ancestors" were dead ends.

When a species becomes widespread, it is subjected to different pressures in different places. Subpopulations form as groups get out of touch with each other. The situation amounts to a whole lot of experiments going on at once. Some branches die out, others lead to a lot more branches.

[Texasforever]

When we got a lot more fossils, it was clear that the earlier depiction was wrong and some of the "ancestors" were dead ends.

Yes and as knowledge grows all assumptions are challenged and revised as needed but nothing in evolution as espoused today accounts for that, as yet to be defined, "human spark of intelligence".