For decades, scientists have debated about how the first modern humans reached Sahul — the prehistoric supercontinent that once connected Australia, New Guinea, and Tasmania. Archaeological evidence has long pointed to human presence at least 60,000 years ago, while earlier genetic studies struggled to match that timeline. Now, a newly published genomic analysis appears to settle the dispute and reshapes what we know about early human expansion across the Indo-Pacific.
A major study titled “Genomic evidence supports the ‘long chronology’ for the peopling of Sahul”, published on 28 November 2025 in Science Advances, concludes that early humans entered Sahul around 60,000 years ago through two distinct migration routes rather than a single pathway. The investigation is led by an international team including Francesca Gandini of the University of Huddersfield as lead researcher and maritime archaeologist Helen Farr of the University of Southampton.
Drawing from 2,456 complete mitochondrial genomes from Indigenous communities across Australia, Papua New Guinea, Island Southeast Asia, and the Western Pacific, the team produced one of the most extensive genetic reconstructions ever made for this region. Their analysis combined mitochondrial DNA, Y-chromosome markers, and genome-wide comparisons with archaeological and climatic datasets.
The evidence points to two major streams of migration emerging from different parts of ancient Southeast Asia. One group appears to have followed a northern passage — moving through the Philippines, Sulawesi, and into northern New Guinea and northern Australia. A second, equally ancient migration followed a southern maritime route, likely passing through island chains south of Sundaland before entering Australia via a separate coastal corridor.
Gandini explains that the two-route model is no longer speculative. “Our mitochondrial data reveal deep divergences between lineages that clearly track back to different entry points into Sahul,” she said. “Some of the oldest maternal lineages found exclusively in Australia and New Guinea show divergence times around 60,000 years ago, strongly supporting the long chronology. These patterns cannot be explained by a single wave of migration.”
Farr emphasizes that such migrations required deliberate, coordinated seafaring rather than accidental drift. “These people were not clinging to logs and hoping for the best,” she said. “They were undertaking intentional blue-water crossings. Their movement across island arcs and open sea indicates a sophisticated level of planning, navigation, and boat-building far earlier than previously assumed. This study reinforces that modern humans had maritime capabilities tens of thousands of years before similar evidence appears elsewhere.”
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Uncertainty but Robust
The long chronology hypothesis — the idea that humans arrived in Sahul around 60,000–65,000 years ago — aligns well with archaeological findings such as early sites at Madjedbebe in northern Australia. Until recently, however, genetic models had tended to cluster Sahul’s settlement date closer to 50,000 years ago. The new paper argues that older estimates were constrained by limited data and by molecular-clock models that underestimated mutation rates for certain lineages. Using a more comprehensive dataset and comparisons with remote Pacific populations where lineage ages are well understood, researchers recalibrated the timeline and found strong support for earlier arrival.
Gandini notes that the molecular clock still comes with uncertainty but insists the new timelines are robust. “Genetics will always have margins of error, but the weight of evidence now firmly supports earlier settlement,” she said. “And this is only the beginning. We are already analyzing hundreds of whole genomes — billions of base pairs — to verify whether the deep splits we see in mitochondrial DNA are mirrored across the autosomal genome.”
The presence of two ancient migration routes into Sahul also helps explain one of the region’s most striking features. Its extraordinary cultural, linguistic, and genetic diversity. New Guinea alone holds more than 800 languages, and Australia contains some of the world’s longest continuous cultural traditions. According to Farr, the dual-route model offers new insight. “Multiple points of entry bring multiple ancestries, multiple technologies, and perhaps different symbolic traditions,” she said. “This may help us understand why Sahul developed such a rich mosaic of cultures so early in human history.”
Environmental Challenges
Beyond human ancestry, the findings highlight the environmental challenges early migrants faced. During the late Pleistocene, sea levels were much lower, but long stretches of open water still separated Sunda (mainland Southeast Asia) from Sahul. The journey into Sahul required intentional island-hopping across multiple exposed continental shelves and deep ocean gaps — a feat that demonstrates advanced adaptation to tropical maritime environments.
Scholars in the wider scientific community have reacted positively, noting that the study finally brings genetic timelines in line with archaeological records. Many archaeologists have long argued that signs of human activity older than 60,000 years in Australia were being unfairly dismissed due to inconsistencies in genetic data. With this study, the gap appears to be closing.
Still, the authors acknowledge that questions remain. The exact geographic starting points of the two migration routes are not fully resolved, and ongoing genome-wide research may reveal further complexity — potentially even more than two migration waves.
For now, though, the study marks a major milestone. It strengthens the link between early human dispersal out of Africa and the rapid expansion across Asia and Oceania, portrays Sahul as one of the earliest regions outside Africa to be settled, and reframes our understanding of prehistoric human mobility.
“Modern humans were explorers from the beginning,” Gandini said. “The story of Sahul shows that our ancestors were capable of extraordinary journeys — far earlier and far more intentionally than most of us ever imagined.” (Sulung Prasetyo)
