I see made-for-TV documentaries on the various theories and evidence several times a year..(The Discovery Channel and it's ilk) and there is more & more evidence for the ideas noted in the abstract Wolfgang quotes. One group has collected DNA along supposed migration routes from Africa through S.E. Asia to Australia, and found diversity and patterns very close to what would be expected. Others have found support for migration patterns into Europe that further suggest that Africa is the ultimate source.......and yes, there do seem to be 'bottlenecks' along the way (after global catastrophes) that indicate that at one time we came very close to not surviving as a species, meaning that we all have a very small group of common ancestors about 35,000 years ago.