Stochastic models support rapid peopling of Late Pleistocene Sahul

Sam C Lin,Chris Clarkson,Alan N Williams,Richard G Roberts,Laura S Weyrich,Frédérik Saltré,Sue O’Connor,Kasih Norman,Joël Chadœuf,Simon G Haberle,Tobias Friedrich,Tim J Cohen,Corey J A Bradshaw,Michael I Bird,Bastien Llamas,Zenobia Jacobs,Matthew Leavesley,Peter Veth,Sean Ulm

doi:10.1038/s41467-021-21551-3

Abstract

The peopling of Sahul (the combined continent of Australia and New Guinea) represents the earliest continental migration and settlement event of solely anatomically modern humans, but its patterns and ecological drivers remain largely conceptual in the current literature. We present an advanced stochastic-ecological model to test the relative support for scenarios describing where and when the first humans entered Sahul, and their most probable routes of early settlement. The model supports a dominant entry via the northwest Sahul Shelf first, potentially followed by a second entry through New Guinea, with initial entry most consistent with 50,000 or 75,000 years ago based on comparison with bias-corrected archaeological map layers. The model’s emergent properties predict that peopling of the entire continent occurred rapidly across all ecological environments within 156–208 human generations (4368–5599 years) and at a plausible rate of 0.71–0.92 km year−1. More broadly, our methods and approaches can readily inform other global migration debates, with results supporting an exit of anatomically modern humans from Africa 63,000–90,000 years ago, and the peopling of Eurasia in as little as 12,000–15,000 years via inland routes.

Highlights

The peopling of Sahul represents the earliest continental migration and settlement event of solely anatomically modern humans, but its patterns and ecological drivers remain largely conceptual in the current literature
Compared to the mapped archaeological layer, we find most relative support for an initial entry from Wallacea via the southern route onto the now-drowned Sahul Shelf, with a possible second entry later in western New Guinea
By comparing our simulated predictions to the spatial bias- and Signor–Lipps-corrected map layer of timing of first arrival derived from the most-reliable and currently available archaeological data (Fig. 1; see Supplementary Information and Supplementary Data 1), the following characteristics emerged: First, of the eight potential arrival times we considered, there was near-equal support for an entry time at 50 ka compared to 75 ka

Summary

Introduction

The peopling of Sahul (the combined continent of Australia and New Guinea) represents the earliest continental migration and settlement event of solely anatomically modern humans, but its patterns and ecological drivers remain largely conceptual in the current literature. Around 65,000–50,000 years ago (or earlier1), large[2] and apparently well-organized groups[3] of anatomically modern humans first entered the continent of Sahul—the landmass connecting New Guinea, some small islands of modernday Indonesia, mainland Australia and Tasmania at lower sea levels than today. The average distance of residential mobility is a direct function of the available energy in the local environment[28,29,30] These relationships reflect fundamental features in human land use, regardless of the physical or cultural environment, and are useful for constructing generalized predictions of past human dispersal at broad spatial scales to test against archaeological data

Methods

Results

Conclusion