New genomic research indicates that modern humans first arrived on the landmass known as Sahul approximately 60,000 years ago, following two distinct pathways from Southeast Asia.
This finding, published in Science Advances in November 2025, resolves a longstanding debate between archaeologists and geneticists regarding the timing and manner of human settlement in the region.
The study, led by archaeogeneticist Martin Richards from the University of Huddersfield in the United Kingdom, analyzed nearly 2,500 mitochondrial DNA sequences from Indigenous populations across Australia, New Guinea, Oceania, and Southeast Asia.
This unprecedented dataset encompasses the full spectrum of genetic diversity among these populations, allowing researchers to trace migration patterns with greater precision than previous investigations.
The Long Chronology Question
The timing of initial human arrival in Australia has remained contentious within the scientific community. Genetic analyses conducted over the past two decades typically supported a "short chronology," suggesting settlement occurred between 45,000 and 50,000 years ago.
However, some archaeological evidence pointed to earlier dates. Excavations at Madjedbebe, a rock shelter in Arnhem Land in Australia's Northern Territory, yielded optically stimulated luminescence dating suggesting occupation as early as 65,000 years ago, though these findings faced skepticism from certain researchers.
The new genetic analysis strengthens the case for the "long chronology." Richards and colleagues employed molecular clock methodology, which measures the accumulation of mutations in DNA sequences over time to estimate divergence timescales.
By recalibrating mutation rates specifically for these populations and comparing them against populations in the remote Pacific, the team arrived at divergence estimates consistent with settlement around 60,000 years ago.
Two Distinct Routes
The genetic evidence reveals a clear geographic separation between two ancestral populations that entered Sahul independently, both originating from Southeast Asia.
The northern route lineages traveled from the Philippine archipelago and Sulawesi through Papua New Guinea, entering the Sahul continent via the northern coast of present-day Queensland or the Bird's Head peninsula of West New Guinea.
The southern route lineages passed through Malaysia, Java, and Timor, entering Sahul west of what is now Darwin in Australia's Northern Territory.
Both groups, despite divergent geographic origins, departed Southeast Asia at approximately the same time, suggesting coordinated human dispersals rather than isolated voyages.
The genetic modeling suggests that roughly 36 percent of the earliest lineages found in Australia trace back to northern route migrants, while 64 percent derive from southern route ancestors.
In the broader Sahul region, however, most surviving lineages descend from northern route populations, reflecting differential population dynamics and subsequent migrations within the continent.
Seafaring and Environmental Context
The migration into Sahul required crossing open water, with some sea passages spanning up to 100 kilometers.
This achievement underscores the sophisticated maritime capabilities of Pleistocene populations, contradicting earlier assumptions about early human seafaring limitations.
During the period of these migrations, the world's climate was substantially different from today. Lower sea levels—approximately 120 meters below present-day levels—exposed vast continental shelves, creating larger landmasses and facilitating movement through regions now submerged.
The Sunda Shelf, comprising present-day Malaysia, Borneo, Sumatra, and Java, existed as a connected landmass during the last glacial period. Similarly, Sahul encompassed Australia, New Guinea, and Tasmania as a single continent until rising sea levels separated these landmasses approximately 9,000 years ago.
Archaeological Corroboration
The genetic findings align with archaeological evidence recovered from Madjedbebe and other early sites. Excavations at Madjedbebe revealed a continuous human occupation spanning 65,000 years, with distinctive material culture including grinding stones for seed processing, edge-ground stone hatchets, and ground ochre pigments.
These artifacts demonstrate technological innovation and economic sophistication among the earliest inhabitants of Australia.
Christopher Clarkson, an archaeologist from Griffith University who conducted the Madjedbebe research, described the new genetic study as a "very satisfying integration of various lines of evidence," noting it represents the first comprehensive study connecting archaeology, genetics, seafaring capabilities, timing, and climate data.
Subsequent Dispersal Patterns
Evidence from the genetic analysis suggests that some northern route pioneers rapidly continued eastward to the Bismarck Archipelago and Solomon Islands shortly after their arrival in Sahul, beginning extensive settlement of the Near Oceania region.
Y-chromosome data corroborates mitochondrial DNA patterns, supporting the model of distinct northern and southern dispersals into Sahul from different sources within Southeast Asia.
Methodological Considerations
The study acknowledged gaps in the available evidence. Ancient DNA samples from southern Asia and the submerged regions of Sahul remain scarce, limiting direct genetic verification of timing and pathways.
The researchers applied multiple statistical methodologies and cross-referenced mitochondrial DNA analysis with Y-chromosome data and archaeological findings to strengthen their conclusions.
Critics and independent researchers noted that molecular clock calibration remains challenging. Different mutation rate calculations can yield substantially different age estimates.
The team addressed this by developing correction curves for mitochondrial DNA evolution rates specific to these populations, as mutation rates do not accumulate uniformly over time in all lineages.
Implications for Understanding Early Human History
This research contributes to a broader understanding of human dispersal from Africa and adaptation to diverse environments. The two-route entry into Sahul demonstrates that early modern humans possessed both the cognitive abilities and technological sophistication necessary for long-distance seafaring and settlement in novel environments.
The presence of ground pigments, specialized tools, and evidence of plant processing at the earliest occupation levels indicates cultural complexity and symbolic thinking among these pioneer populations.
The findings also affirm deep historical connections for Indigenous Australian and Papuan populations, with continuous occupation of their ancestral lands spanning six decades of millennia.
As Helen Farr from the University of Southampton emphasized in the study's discussion, this research recognizes that the ancestors of these populations have inhabited Sahul for tens of thousands of years—a timeline consistent with oral traditions and cultural records maintained within Indigenous communities.
Future research involving ancient DNA recovery from human remains, continued archaeological investigation, and refinement of molecular clock methodologies may further clarify the settlement process and identify additional details about these early populations.
The integration of multiple lines of evidence—genetic, archaeological, and environmental—establishes a more robust framework for understanding one of humanity's most significant dispersal events.
