The ancient landmass known as Sahul – which includes Australia, Tasmania and New Guinea – was home to groups of humans as early as 60,000 years ago, according to genetic data. This finding suggests that our ancestors may have made it Down Under just ten millennia or so after first setting foot outside of Africa, which is pretty impressive if you think about it.
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Recent genomic studies have suggested that Indigenous groups across the region can trace their ancestry back only to around 50,000 years ago. However, not everyone accepts this scenario – which is referred to as the “short chronology” for the peopling of Sahul – as some archaeological discoveries in the area have been dated to earlier than this point.
The only way this makes sense is if these older relics were left behind by a group of people who simply vanished without leaving any descendants. Speaking to IFLScience, Professor Martin Richards from the University of Huddersfield said that “you’d have to assume that all those early archaeological dates between 50,000 and 60,000 years ago were people who got wiped out by another wave of people who came through.”
Given the distance between Africa and Sahul, however, it’s reasonable to think that only a very well-established and successful population could ever make it that far, which makes it difficult to accept that these intrepid migrants could so easily disappear after arriving in Oceania. To figure out what really happened, Richards and his colleagues analyzed 2,456 mitochondrial genomes from the region, “encompassing the full range of diversity from the indigenous populations of Australia, New Guinea, and Oceania.”
This enabled the researchers to create an evolutionary tree which could be traced back to other populations in Southeast Asia and ultimately to Africa. Overall, results indicate that the earliest ancestors of these Aboriginal communities left Africa in the wake of a “nuclear winter” triggered when Sumatra’s Mont Toba erupted about 74,000 years ago, and had reached Sahul by around 60,000 years ago.
Contrary to previous studies, this scenario represents what is known as the “long chronology” for the peopling of Sahul. “From the point of view of the archeological and fossil evidence, I think our results match up much better [than the short chronology],” says Richards.
Furthermore, by looking at the distribution of different genetic groups – or haplogroups – across Oceania, the study authors were able to identify two separate routes by which these early settlers reached Sahul from Sundaland – which encompasses much of Southeast Asia.
“There are some [haplogroups] that are restricted to the north and some that are restricted to the south, and the ones that are restricted to the south tend to link back more to mainland Southeast Asia and India,” says Richards. “But one of the most ancient, widespread haplogroups has ancestral links back to the Philippines. So this points to two different migrations, one that came out of mainland Southeast Asia and spread around the coast of Australia, and then the other one coming into New Guinea.”
“Both routes trace back to South Asia and ultimately to Eastern Africa [around 75,000 years ago]”, write the study authors. What’s more, given that both routes would have required extensive sea voyages – possibly involving stretches of open water in excess of 100 kilometers (67 miles) long – it’s clear that these early globetrotters had mastered the art of sailing by this point in human history.
Summarizing the significance of their data, the researchers say that they “have addressed and refined a Western science narrative that supports the peopling of Sahul in deep time but acknowledges and respects the ontological perspective that many Indigenous people hold: “We have always been here”.”
The study has been published in the journal Science Advances.
Source Link: People Sailed To Australia And New Guinea 60,000 years ago
