>>12128256You have to realise that evolution is a slow and gradual process that takes millions of years. As long as environmental hardships and sexual preferences exist, it can move with pace.
Species like chimps and hominids branched off from a common ancestor which died out. The idea that one transformed into the other is the wrong way to think about it.
As for growing fur, we started wearing clothing. In some climates we'd die without it. The hairiest of us might survive a little better on the outskirts of the colder regions and produce hairy babies that survive to make hairier babies.
The thing with humans though, we got smarter.
Now our evolution is driven by attractiveness and intelligence, not our ability to live through tough conditions and not die or be eaten.
