The earliest human trans-oceanic migration event in human history


Anatomically Modern Humans dispersed rapidly through Sunda and Wallacea and arrived in Sahul (the combined landmass of Australia and New Guinea joined at times of lowered sea level), before 50,000 years ago. The establishment of a viable founder population in Sahul from the islands of Wallacea necessarily involved several prior water crossings. Multiple routes through Wallacea to Sahul have been proposed and all involve at least one open ocean, multi-day voyage approaching 100 km. This paper first considers the constraints and opportunities imposed by the palaeoenvironments and palaeogeography of the region at the time of human dispersal. It will present inter-visibility and drift simulation evidence that multiple crossings between inter-visible locations were possible, with varying degrees of difficulty. These routes can be broadly categorized into those making landfall on the Northwest shelf from Timor-Roti, and those arriving on the Brid’s Head in New Guinea from a number of islands east of Sulawesi.  Drift modelling suggests that the chance of random arrival was small by any route. However, even minimal directed headway at optimal times of the year, both implying purpose on the part of the voyagers, greatly improves the chances of making a successful landfall. Demographic modelling indicates that a founding population of between 1,300 and 1,550 individuals was necessary to maintain a quasi-extinction threshold of ≲0.1. This minimum founding population could have arrived at a single point in time, or through multiple voyages of ≥130 people each over ~700–900 years. This result shows that substantial population amalgamation in Sunda and Wallacea in Marine Isotope Stages 3–4 provided the conditions for the successful, large-scale and probably planned peopling of Sahul.


Michael Bird trained as a geologist at the University of Sydney and the Australian National University, obtaining a PhD in isotope geochemistry in 1988. Following a postdoctoral fellowship at the University of Western Ontario in Canada, he returned to Australia as research Fellow, Queen Elizabeth II Fellow and Fellow at the Research School of Earth Sciences, Australian National University. In 2000 he took up an Associate Professorship in Singapore and in 2004 moved to the Chair in Environmental Change at the University of St. Andrews in Scotland. He returned again to Australia in 2009 to take up a and Australian Research Council Federation, then Laureate Fellowship. He is currently a Distinguished Professor in the College of Science and Engineering at James Cook University (Cairns campus). He leads a research group focused terrestrial biogeochemistry and environmental change in tropical Australia and Southeast Asia.

Link to related publication

Early human settlement of Sahul was not an accident (


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