Very intereting question. I am afraid neodarwinism have no coherent answer to it - there would be probably many untestable stories of evolution of it. I don't know when the fur evolves during embryonic development of apes. I would bet on late stages. In that case I guess the neoteny would be probably the answer of my taste. Human morphological development is so to say interrupted and people look most embryo-like comparing other primates. People are also so to say born prematurely, they should have been in uterus for one year more.
(and there is no physiological explanation why they are not. Those mothers who bear children longer should have had some survival advantage)
So the first year of their life they are totally dependent on their mothers and we can speak about social-uterus development. It coincides with following development of language, stance etc which cannot be reduced and compared to other primates. Human are special and on my opinion their evolution cannot be explained by evolution of primates.
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