Modern humans spread out of Africa beginning around 60,000 to 70,000 years ago (though the precise timing is still a matter of active research).

One major dispersal route went along the southern coast of Asia — through what is now India, Southeast Asia, and eventually to Australia and New Guinea, which were connected by lower sea levels and could be reached by short water crossings even then.

The populations that took this southern route, and that eventually settled Australia and New Guinea, are the ancestral populations whose genetic legacy is most relevant to the Population Y discussion.

A separate dispersal, somewhat later, went through northeastern Asia and eventually into Beringia and the Americas.