Mitochondrial DNA Analysis of 2,456 Genomes Confirms Humans Reached Australia 60,000 Years Ago via Two Separate Maritime Routes
An analysis of 2,456 mitochondrial genomes published in Science Advances identifies two distinct maritime routes humans used to reach Sahul roughly 60,000 years ago.
Overview
A large-scale analysis of mitochondrial DNA has provided the most detailed genetic evidence to date that modern humans reached the combined landmass of New Guinea and Australia — known to researchers as Sahul — approximately 60,000 years ago. The study, published in Science Advances, examined 2,456 mitochondrial genomes from Aboriginal Australians, New Guineans, and populations across Southeast Asia and the western Pacific, identifying at least two genetically distinct migration routes from the now-submerged continent of Sundaland.
The research was led by Francesca Gandini and colleagues, with principal investigators Professor Martin Richards at the University of Huddersfield and Professor Helen Farr at the University of Southampton, funded by the European Research Council. A companion study by Dr. Pedro Soares at the University of Minho, published in Scientific Reports, provided additional validation of the findings.
Two Routes Across Open Water
By tracing the gradual accumulation of mutations in maternally inherited mitochondrial DNA — a technique known as the molecular clock — the team identified two separate clusters of genetic lineages that diverged before the settlement of Sahul. One group corresponds to a northern route leading into the Bird’s Head peninsula of West New Guinea, while the other traces a southern corridor from Sundaland directly into what is now northern Australia.
The genetic data indicate that migrants following these routes crossed stretches of up to 100 kilometers of open water, providing some of the strongest evidence yet for early maritime capabilities among modern humans leaving Africa. During periods of lower sea level, island chains between Sundaland and Sahul would have been more exposed, but significant water crossings remained unavoidable.
“This reflects the really deep heritage that Indigenous communities have in this region,” Professor Farr stated, emphasizing the antiquity and resilience of the populations who made these voyages.
Settling the Chronological Debate
The timing of human arrival in Australia has been contested for decades. A “short chronology” camp argues that reliable archaeological evidence places first settlement at roughly 45,000 to 50,000 years ago, while the “long chronology” position — supported by luminescence dating at sites such as Madjedbebe in the Northern Territory — pushes the date back to 53,000-65,000 years ago.
The new genetic analysis lands firmly in the long chronology camp. By dating the oldest mitochondrial lineages found exclusively in Aboriginal Australians and New Guineans, the researchers arrived at a settlement window centered on 60,000 years ago. “We feel that this is strong support for the long chronology,” Professor Richards stated, while acknowledging that future whole-genome analyses could further refine the estimate.
The study also integrated Y-chromosome data and genome-wide analyses alongside climatological modeling, providing cross-verification from multiple independent genetic systems.
Implications for Early Human Behavior
Beyond the dating question, the research carries broader implications for understanding early human cognition and social organization. Crossing 100 kilometers of open water — even with reduced sea levels — would have required some form of watercraft and, likely, the ability to plan multi-day voyages with groups large enough to establish viable populations on arrival.
The evidence of possible interbreeding between modern humans and archaic species such as Homo floresiensis along these migration routes adds another dimension. If confirmed, such contact would extend the pattern of interbreeding already documented between modern humans and Neanderthals in Europe and Denisovans in Asia to the island corridors of Southeast Asia.
What Remains Unknown
While mitochondrial DNA provides a clear maternal lineage, it captures only one thread of genetic history. The researchers noted that whole-genome sequencing of ancient remains from the migration corridor — should such specimens be recovered from tropical environments where DNA preservation is poor — would provide a more complete picture. The exact number of individuals involved in the founding populations, and whether the two routes reflect separate migration events or a single dispersal that split along the way, remain open questions.