Why Did Early Humans Leave Africa?

[stopdiggin]

2. another great link

Love this stuff. Thanks, Judi.

If I can attempt to answer, without really answering ...
1) homo sapiens never truly did leave Africa (as in there was always a population that remained behind)
2) Without knowing the exact trigger (if in fact there was one) it seems very likely that our species expanded their range for largely the same reasons that others do. Some combination of scarcity of resources, combined with newly discovered (or newly discovered ways to exploit) resources over the horizon. But the short answer is, populations that are having their needs met tend to stay with the familiar -- and populations that are under stress try new behaviors and territory in an effort to adapt.

(and then there is the fondness for theories that suggest some kind of 'cognitive' evolutionary leap -- that led to radically different behavior and abilities -- which are, again, pretty interesting but also pretty speculative at this point.)