But what about before that?

Evolution doesn't deal with the origin of the universe at all. That's cosmology (which is part of physics, while evolution is a big part of biology). If you want to look into scientific ideas about the origin of the universe I would recommend Alan Guth's _The Inflationary Universe_ and possibly Stephen Hawking's _A Brief History of Time_

I thought tha it was the case that some groups of humans did have differences with adaptive significance - in addition to skin colour there is the greater lung capacity of mountain peoples and, I believe, (although this is not directly related to environment as the term is understood in general usage) lactose tolerance.Also humans, although widespread, have a low genetic diversity compared to most other species so we should not expect too much in the way of differences at this point. The fact that humans have spread as well as they have strongly suggests that technology (in the widest sense of the word) is an adequate substitute for "natural" abilities that might evolve.