Anatomically, we haven't changed much in the last 300000 years, we've lived in North Africa and the Near East for at least 100000, so why did we seemingly sit around for 90 thousand years and then suddenly, invent farming and found egypt?
AND seemingly independently, on the other side of the world, they Maya seem to do the same thing, roughly at the same time?
Some enlightening answers can be read in this older thread