Islands Under the Sea: A Review of Early Modern Human Dispersal Routes and Migration Hypotheses Through Wallacea

Wallacea is the transitional biogeographic zone between the continents of Sunda (Southeast Asia) and Sahul (Australian-New Guinea). It consists of a series of island chains unique in the region for never having been connected to either continent. Movement of early modern humans from Sunda to Sahul during the late Pleistocene required dispersal through Wallacea, and hence would have necessitated sea crossings. However, the archeological evidence for early modern humans in Wallacea is still a work in progress, and none of it pre-dates the archeological record from Sahul. While numerous models of this significant colonization event have been proposed, selecting the most likely model for first landfall in Sahul using current archeological evidence has proven difficult, if not impossible. Here the late Pleistocene archeological evidence of early modern humans from Wallacea and its neighbors are reviewed, and the key colonization models that have been proposed are explored. We consider the use of computer simulations and the input variables necessary to test the likelihood of the different colonization models. We highlight the importance of the greater than 100 additional submerged islands observed within the Wallacean archipelago following a simple analysis of bathymetric data and sea-level curves, and their potential impacts on the dispersal and ecology of early human colonizers.