I am sure among the dozens of species of ape-human like man from neandertal(sp) to all hominids & on..some were covered in fur/hair. :}
I could be wrong but I am sure over time, evolution would work things out, such as if humans were covered w/ fur.. & still used animal hides & furs for clothing, that would not be so great in the long run hygine wise. Having a body covered in fur/hair invites pests,mites,bacteria of all sorts to live on us with ease. But I guess it really depends on the enviroment & time we are talking about, obviously man was smart enough to make clothing & tools so full body of hair was not needed. The apes are obviously not smart enough to work that out so they do better off fully-furred
but you see how they make grooming a family hobby.. >.<