“One of the Last Places on Earth Reached by Humans” –Ancient DNA Reveals Seafaring Exploration and Settlement of the South Pacific




A study of ancient DNA has shed light on the epic journeys from Vanuatu –a South Pacific Ocean nation made up of roughly 80 islands that stretch 1,300 kilometers–that led to the settlement of the remote Pacific islands by humans. The region was one of the last on Earth to be permanently settled by humans who used out-rigger canoes to traverse hundreds of miles of open ocean. Two separate studies tracked changes over time in the genetic make-up of people inhabiting Vanuatu – regarded as a gateway to the rest of the Pacific.

Vanuatu — an 80-island archipelago strewn across 1,300 kilometres of the southern Pacific Ocean — was one of the final pockets of the planet to be reached by humans, with its first inhabitants arriving only 3,000 years ago. For more than a century, researchers have puzzled over why its inhabitants speak languages rooted in southeast Asia, but trace most of their genetic ancestry to what is now Papua New Guinea, which has its own distinct languages. The genomic studies now suggest that a series of population replacements on the islands led to this unusual situation.


Until recently, one explanation for the islands’ language and genetic mismatch had been that the first people who settled Vanuatu and the rest of remote Oceania were from a seafaring culture known as the Lapita, who traced their ancestry back to Taiwan but emerged through what is present-day Papua New Guinea. When they arrived in Vanuatu, they carried some Papuan ancestry but still spoke languages from a linguistic family common in the islands of southeast Asia, called Austronesian. But ancient genomes from some of Vanuatu’s first settlers, published in 20163, scotched that theory. The archipelago’s earliest inhabitants carried little Papuan ancestry. This discovery posed an obvious question: when did Papuans get to Vanuatu?


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Prof David Reich, from Harvard Medical School, said the region had a "tremendous" range of human diversity, adding that Vanuatu itself had an "extraordinary diversity of languages" in a relatively small area. The number of languages spoken in the tiny island state is thought to number more than 130, though several are endangered with just a small number of speakers.

The first people to arrive in the islands belonged to the Lapita culture, said co-author Dr Cosimo Posth, from the Max Planck Institute for the Science of Human History in Jena, Germany, who expanded out of Taiwan between 5,000 and 6,000 years ago, reaching Vanuatu about 3,000 years ago. "They were really talented seafaring people," he observed. Their secret was the specialised outrigger canoe, which says Dr Posth, "allowed them to cover immense distances of the ocean".

The Lapita voyages represent the most extensive dispersal of agricultural people in history. They carried farming technology and languages belonging to the Austronesian family as far west as Madagascar and as far east as Rapa Nui (Easter Island).

But modern people in the wider region have varying amounts of ancestry from "Papuan" populations like those that live today on New Guinea, and other islands in the Bismarck Archipelago such as the Solomons, New Britain and New Ireland who mixed with people speaking Papuan languages early in their voyages, spreading both types of ancestry throughout the region. Alternatively, it could be explained by more recent seafaring expansions by people from the Bismarck Archipelago.

"The first people of these remote pacific islands had none of the Papuan ancestry from the New Guinea region that is ubiquitous today and everyone has about 25% of it," said Reich, which means that ancestry from the south must have arrived in the region more recently. By studying the DNA of the Vanuatu population through time, the researchers found that people bearing Papuan-like ancestry arrived in the islands around 2,600 years ago. An influx of – mostly male – newcomers steadily transformed the genetic make-up of the island.

All of this happened without a replacement in the language write the researchers. The people of Vanuatu today speak Austronesian languages like those presumably spoken by the Lapita –a "lingua franca" developed in the region among seafaring, mobile people voyaging and trading across long distances.

Other peoples of the Pacific, such as people living in Polynesia, derive their Papuan ancestry from a different source to the one that populated Vanuatu.

"What we're detecting is not one, but at least two movements of Papuan ancestry out into the Pacific," said Reich. These other movements remain a focus for future studies. "All the islands in eastern Polynesia – from the Cook Islands to Hawaii, New Zealand, French Polynesia – were settled much later, about 1500 years after the Lapita expansion. So there must have been further technological advancements [to the initial outrigger canoe design] that allowed people to spread even further east."

Reich’s team discovered hints that Papuan ancestry found on Polynesian islands west of Vanuatu came from yet another source. “There’s very clear evidence of not one, not two, but at least three big eastward migrations from the big islands in Indonesia and New Guinea,” Reich says. “This is only the tip of the iceberg.”

The Daily Galaxy via Nature  and BBC  

Image credit: With thanks to Turtle Bay Resort

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