What's wrong with foreskins?
Nothing really: I just got carried along on a wave of emotion, in the heat of the moment. Also , how could I condemn bare bell-ends on an ex-muslim forum?
Back to unibrows:- I reckon that the use of brows isn't restricted to sweat deflection; it's probably used more importantly in facial expression along with other body language and also to help shield the eyes from the elements. Both of these attributes probably evolved as aids to avoid ambush or unsafe encounters and hence improve individual and group survival.
Anyway, you could always comb a unibrow to left and right whilst always remembering to put in a centre-parting. It would look a bit silly if you put it halfway over one eye, wouldn't it.