Humans were down to 10,000 units at some time. Maybe some leader consolidated power and convinced the tribe to embark in a journey to move somewhere else where

Humans were down to 10,000 units at some time. Maybe some leader consolidated power and convinced the tribe to embark in a journey to move somewhere else where water was more plentiful and food too, we can only imagine that ...had his attempt at convincing the tribe been unsuccesful we would not be here today! Or maybe the opposite, which is also true...somebody level headed convinced the tribe not to embark in such a journey...to stay, because with so few units it was not the time to make experiments or gambles