what is man's orgin.
Atheist Answer: 

Something which was very nearly a man (or woman), but was technically an ape according to our modern classification system.

The offspring was very slightly mutated; it was just different enough from its ape parents to get across our arbitrary line and be properly human. Whatever was different, it was probably something beneficial like longer legs, stronger hands or a bigger brain.

Of course, the first human didn't care about classifications and it didn't know it was human. We just think about it this way in retrospect.

- SmartLX