A map showing the migration of the first settlers to Sahul 60,000 years ago. Credit: Helen Farr and Erich Fisher

A collaboration between the University of Huddersfield’s Archaeogenetics Research Group and the University of Southampton’s Center for Maritime Archaeology, has clarified the first settlement of New Guinea and Australia by modern humans, Homo sapiens—refining our understanding of the origins of seafaring and maritime mobility.

The work was led by maritime archaeologist Professor Helen Farr at the University of Southampton, with the archaeogenetics team led by Professor Martin Richards at Huddersfield.

During the last Ice Age, when sea levels were much lower than they are today, New Guinea and Australia were part of a single landmass, which is known as Sahul. We know that our species, Homo sapiens, evolved in Africa, but there has been a long-running debate about both the timing of the first settlement of Sahul and the routes by which people first traveled to the super-continent.

New research sheds light on migration

The new research, a collaboration between archaeogeneticists, archaeologists, earth scientists and oceanographers and published in the journal Science Advances, has cast light on the who, where and when of this early maritime migration.

We know that the ancestors of New Guineans and Aboriginal Australians have inhabited Sahul for tens of thousands of years, with many Aboriginal Australians understanding that they have always been on country. Yet, for Western scientists and archaeologists, the details of global dispersals have remained controversial. There are two views on the timing of the settlement—the "long chronology," suggesting that the first settlement goes back to about 60,000 years (60 ka) and the "short chronology," which argues for a first landfall about 45–50 ka.

The interdisciplinary team, including colleagues at the University of Minho in Portugal, at La Trobe University in Australia, and the University of Oxford, focused firstly on human mitochondrial DNA (mtDNA) genomes to address this question. The mtDNA is found in the mitochondria, the "battery packs" of our cells, which are found outside the cell’s nucleus, where the rest of our DNA is packaged. As a result, it is inherited only from our mothers, and the way the mtDNA sequences vary from one person to the next can therefore be used to recreate the maternal genealogy in incredible detail.

Genetic analysis and migration routes

The team analyzed almost 2,500 mtDNA genomes from Aboriginal Australians, New Guineans, and people from the western Pacific and Southeast Asia. They used these to build a genealogical tree and looked at the way the lineages in the tree were distributed from one population to the next. All DNA changes gradually over time, and they used the rate of change in the lineages—known as the "molecular clock"—to date lineages from each region.

The team checked the accuracy of the clock against islands with known colonization times in the Remote Pacific—data contained in a recent paper published in Scientific Reports by a similar interdisciplinary team including both Professor Richards and Professor Farr, and led by Dr. Pedro Soares of the University of Minho.

Modern humans, Homo sapiens, evolved in Africa, and mtDNA clearly shows that there was only one main successful migration of modern humans out of Africa, which the team dated to about 70,000 years ago. They then found that the most ancient lineages seen either in Aboriginal Australians, New Guineans, or both, but nowhere else, dated to about 60,000 years, coming down firmly in support of the long chronology.

The ancestry of the most ancient lineages could be traced back to Southeast Asia. The team found that while the majority traced back to more northerly parts of Southeast Asia—northern Indonesia and the Philippines—a significant minority traced to more southerly parts—southern Indonesia, Malaysia and Indochina. This suggested there were at least two distinct dispersal routes into Sahul. Moreover, the northern route lineages spread all over New Guinea and Australia, whereas the southern route lineages were restricted to just Australia in the south. But both sets of lineages dated to around the same arrival time.

Finally, the team tested the results against a detailed re-evaluation of Y-chromosome (inherited down the male line of descent) and genome-wide data (inherited down both lines of descent), as well as the archaeological, paleogeographical and environmental patterns, to incorporate the whole range of available evidence.

Challenges and significance of findings

It is important to remember that these results have been inferred by looking at modern mtDNA variation and working backwards. In recent years, ancient DNA (aDNA) has become an extremely valuable source of direct information about our past. Unfortunately, though, DNA rarely survives in human remains from the tropics.

In collaboration with the aDNA lab in Harvard, the team did in fact recover DNA from one archaeological sample, from the Indonesian Iron Age. This pointed to ancient "reverse" migrations back west into Indonesia from New Guinea, but it was much too recent to tell us anything about the first settlement.

The work is especially significant, however, because although the new genetic results fit well with the archaeological and paleoenvironmental picture, in the last few years, many geneticists have been moving in the opposite direction, towards a short chronology.

That argument has rested on the re-dating, using a different kind of genetic clock, of the time that the archaic Neanderthals met and interbred in the Middle East with the ancestors of modern non-Africans—who all carry around 2% Neanderthal DNA as a result. Some recent results have suggested that this was much more recent than had been previously believed—less than 50,000 years ago. Since all non-Africans seem to share this ancestry, if correct, this would mean the descendants of modern New Guineans and Aboriginal Australians—who carry the Neanderthal DNA—could only have arrived after this.

However, there is archaeological and fossil evidence for modern humans in Southeast Asia and Australia which has been dated to at least 60,000 years, so proponents of the short chronology have to argue that these early pioneers were all wiped out by a later wave of modern humans.

On the other hand, the findings of the new paper suggest modern Aboriginal Australians and New Guineans are descended instead from those first pioneer settlers, 60,000 years ago.

Looking ahead to future research

Professor Richards said, "We feel that this is strong support for the long chronology. Still, estimates based on the molecular clock can always be challenged, and the mitochondrial DNA is only one line of descent. We are currently analyzing hundreds of whole human genome sequences—3 billion bases each, compared to 16,000—to test our results against the many thousands of other lines of descent throughout the human genome.

"In the future, there will be further archaeological discoveries, and we can also hope that ancient DNA might be recovered from key remains, so we can more directly test these models and distinguish between them."

Professor Farr added, "This is a great story that helps refine our understanding of human origins, maritime mobility and early seafaring narratives. It reflects the really deep heritage that Indigenous communities have in this region and the skills and technology of these early voyagers."

More information: Francesca Gandini et al, Genomic evidence supports the "long chronology" for the peopling of Sahul, Science Advances (2025). DOI: 10.1126/sciadv.ady9493

Citation: New Guineans and Aboriginal Australians descend from two groups who arrived 60,000 years ago, research suggests (2025, December 25) retrieved 25 December 2025 from https://phys.org/news/2025-12-guineans-aboriginal-australians-descend-groups.html

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