spencer wells who studied under Cavalli-Sforza
published a book Journey of Man (as well as a national geographic documentary) which did an huge study of y chromosome genes which
are passed along the male line (although theres been some recent talk that it can be passed along the female line as well)

and by studying the dna was able to map human migrations --
quite fascinating although Id like to hear from opposing views from geneticists.. (such as those who studied mitochondrial dna in female genes)

the study indicated that not only did humans come of out Africa and displace the rest of the human populations it was much more recent than anyone had expected. Ie. 50-60,000 years ago. From Africa along the southasian coast to Australia, subsequent migrations that came out from Africa again and went to central asia - split into some going to Europe and more going to Asia - north America. etc.

it was a fascinating book and documentary..
even though Wells encountered some unexpected opposition from native peoples in Australia or North America, one goes away thinking about how closely related we all are, and just how incredibly resourceful people are to survive in many harsh environments.

on another note..Scientific American had story on using, the genetic variation of stomach bacteria to map human migrations - just another tack on the problem.

it is an interesting window - prior to the revolution in dna studies,
such a survey would not be possible, and a few generations from now, with travel and intermixing of populations the dna will have become to diluted ..