Reconstructing Palaeogeography and Inter-island Visibility in the Wallacean Archipelago During the Likely Period of Sahul Colonization, 65-45 000 Years Ago

Abstract

The palaeogeography of the Wallacea Archipelago is a significant factor in understanding early modern humancolonization of Sahul (Australia and New Guinea), and models of colonization patterns, as well as archaeologicalsurvey and site interpretation, are all heavily dependent on the specific palaeogeographic reconstruction employed.Here we presentfive reconstructions for the periods 65, 60, 55, 50, and 45 000 years ago, using the latest bathometricchart and a sea-level model that is adjusted to account for the average uplift rate known from Wallacea. Using this datawe also reconstructed island areal extent as well as topography for each time period. These reconstructions were thenused to estimate visibility for each island in the archipelago, andfinally to model how intervisible each island wasduring the period of likely human colonization. Our models provide thefirst evidence for intervisibility between Timorand Australia at ca. 65–62 ka and 47–12 ka, the second of which is notable for its overlap with the oldest radiocarbondates from Timor-Leste and Australia. Based on intervisibility alone, however, our study suggests that the northernroute into Papua New Guinea was the most parsimonious route forfirst modern human entry into Sahul. Our studyprovides archaeologists with an important baseline from which to conduct physical surveys, interpret archaeologicaldata, and theorize the colonization of Wallacea and Sahul.