This shows how waves of humans spread throughout the world from their origins in Africa over a period of some 50,000 years. The video was created by geneticist Daniel Falush of University College Cork in Ireland and colleagues. For more info, go here: http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1000078
Soundtrack courtesy of Garageband
Why do some paths not persist? Was SE Asia, for instance, really "colonized" multiple distinct times before humans stuck there? I guess I should go look at the original source publication.
I think there may have been colonies that were setled and died out, but I also think there were waves of colonization, some moving in and overwhelming the previous settles, some melding with those who came before, and some coming in a setting up separate (even ruling) groups. Human migrations to the British Isles show this very well.
In 50K years, we've had the opportunity to try just about every combination of migration scheme.