The ability to build and use watercraft probably evolved very late in homo sapiens evolutionary history, and was certainly not part of an early archaic homo sapiens toolkit. what are some possible explanations for the presence of archaic homo sapiens sites on southeast asian islands such as java?

Although the answer to this question remains uncertain, one theory is that an ancient land bridge may have allowed fauna from what is now China to reach Java. The theory is that the present-day Philippine Islands once formed part of a land bridge between mainland China and present day Java. This allowed vertebrates from the Chinese mainland to colonise Java. Supposedly, this occurred around the Pleistocene.