The puzzle of why humans have so much skin exposure has always bothered me. I read some time ago that northern hemisphere groups such as the inuits had the eyes set the way they were for an evolutionary reason. The article said the eyes were configured that way to deal with the glare off of the snow they hunt on. Made sense to me, but why would early cold region groups not evolve to keep their hair for warmth?
This article gives some possibilities why we shed so much hair. I have to admit I have never noticed if a person of color blushes though I expect they do, I just never took time to try and look for it. If we were looking to be scarier to our enemies of the past, dark body and facial hair seems more intimidating than slight changes in skin color. That's just my opinion though.