There is a very good book called Timewalking which I have somewhere about the house which goes into a great deal of detail about the settlement of the Earth by our forefathers.I can't recall it's author but it is well worth looking out.
One of the points which I think is made in the book is that for at least a quarter of a million years early man accumulated the knowledge about his surroundings,the natural world,foodstuffs,geography and technical and social skills that were necessary for the more settled lifestyles that were to follow.
albert