Researchers from The Australian National University (ANU) have helped put together the most comprehensive study ever conducted into the origins of people in Vanuatu -- regarded as a geographic gateway from Asia to the Remote Pacific.

Burial excavations on Uripiv Island Malakula [Cretit: ANU]

The new research, published across two separate research papers, uses a combination of DNA analyses of ancient skeletons and modern samples, as well as archaeological evidence, to put together a complete timeline of migration to the island nation.

The results confirm that Vanuatu's first people were of the Lapita culture and arrived 3,000 years ago from South East Asia, followed by Papuan arrivals from the island of New Britain, in the Bismarck Archipelago just to the east of New Guinea and part of the nation of Papua New Guinea.

Dr Stuart Bedford of the ANU School of Culture History and Language said this was the first time researchers had been able to look at a full sequence of DNA samples from the Vanuatu islands.

"We've been able to track a complete genetic timeline at regular intervals starting with the first inhabitants right through to modern times," Dr Bedford said.

"The very first generation of people into Vanuatu are primarily Asian, then very quickly you see a series of migrations of Papuan people from the Bismarck Archipelago who had been living in the region for around 50,000 years.

"That trend continues over the next 3,000 years right up until today as the genetic ancestry was mostly replaced by that of Papuan migrants. The people of Vanuatu today, like many peoples of the Pacific, can claim a dual heritage."

Anciant skeleton at the Teouma site on Efate [Credit: ANU]

Co Researcher Professor Matthew Spriggs of the ANU School of Archaeology and Anthropology said for the first time researchers could determine exactly where these Papuan migration groups came from.

"They came from New Britain, a Papuan island just east of New Guinea," Professor Spriggs said.

"This makes sense. New Britain has some of the earliest known Lapita sites.

"So what we think happened is that Lapita people after arriving in New Britain moved fairly directly on to Vanuatu and encouraged some of the local populations already in place on New Britain to move there as well."

Dr Bedford said the strength of the Lapita culture was evident in the continuity of the language.

"The Lapita people who originally came to Vanuatu from South East Asia spoke a form of Austronesian," Dr Bedford said.

"That language persisted and over 120 descendant languages continue to be spoken today, making Vanuatu the most linguistically diverse place on Earth per capita.

"This is a unique case, where a population's genetic ancestry was replaced but its languages continued."

The two papers were published in the Nature Ecology & Evolution and Current Biology journals respectively.

The study team was made up of researchers from around the world including at the ANU, the Vanuatu National Museum, Harvard Medical School and the Max Planck Institute for the Science of Human History.

Source: Australian National University [March 09, 2018]

A new experiment by Iowa State University's Elizabeth Swanner that evaluates the reduction of iron in prehistoric oceans may reinterpret the conditions under which iron-rich sedimentary rock is formed.

Graduated cylinder model of the ocean. The green shows cyanobacteria and the brown shows the oxidized iron [Credit: Iowa State University's College of Liberal Arts and Sciences]

Swanner, an assistant professor of geological and atmospheric sciences, was part of an international research team including researchers from the University of Tuebingen in Germany and the Chinese Academy of Sciences in Beijing. The team modeled the prehistoric ocean, similar to that of the Archean Era 2.5 billion years ago within a graduated cylinder.

"We really only wanted to simulate it in the vertical dimension, so we used a graduated cylinder and modified it," Swanner said.

In a previous experiment, the researchers had modified the cylinder to simulate an Archean ocean with large amounts of iron and no oxygen except for what was made by cyanobacteria. Ports along the cylinder's side allowed for sampling at various levels.

"We were studying cyanobacteria because these are the organisms which we think put all of the oxygen in the atmosphere originally," she said.

The research, recently published by Scientific Reports, showed that despite the oxygenation by the cyanobacteria, much of the iron did not remain oxidized but was reduced again into its dissolved form.

This unexpected result may be explained by an enzyme on cyanobacteria which reduces iron. In the modern ocean, which contains at least 1,000 times less iron, cyanobacteria reduce a small amount of iron, but the experiment showed a larger amount of iron reduction than the researchers anticipated. Another possible explanation is that the iron is reduced by a photochemical reaction occurring when the iron is hit by light.

The implications of this finding could change the conditions under which iron-rich sedimentary rocks are thought to be formed from the ancient oceans.

"Traditionally if you see iron enriched in sediments from the ocean you tend to think it was deposited under anoxic conditions," Swanner said. "But potentially we have a way to still deposit a lot of iron but have it be deposited under fully oxygenated conditions."

The initial results in the laboratory prompt new questions for Swanner, including whether she will find evidence of this process in the Midwestern lakes that her research group is now studying. These lakes have iron at the bottom and oxygen only in the top of the water column, and also contain cyanobacteria.

Source: Iowa State University [March 09, 2018]

New genetic research reveals the complex demographic history of Vanuatu, explaining how Austronesian languages were retained throughout its history despite near-total replacement of early Austronesian-Lapita with Papuan ancestry

Young men in canoes in Northwest Malakula, Vanuatu [Credit: Russell Gray & Heidi Colleran]

The study, published in Nature Ecology & Evolution and led by a multidisciplinary research team at the Max Planck Institute for the Science of Human History (MPI-SHH) together with researchers in France, Australia, New Zealand, Germany and Vanuatu, reveals that migrations of people from the Bismarck Archipelago in Oceania to the previously settled islands of the Pacific began as early as 2,500 years ago, much earlier than previously thought. The Remote Oceanian island nation of Vanuatu is the gateway to the rest of the Pacific and understanding its demographic history is critical to uncovering that of the wider region.

The earliest inhabitants of Vanuatu, arriving about 3,000 years ago, were the Lapita peoples who spoke a form of Austronesian language and who had largely East Asian genetic ancestry. But Vanuatu's contemporary population has largely Near Oceanian heritage, showing that over time the genetic ancestry of the early inhabitants was mostly replaced by that of Bismarck Archipelago migrants, who began arriving very soon after initial settlement. Yet the original Austronesian language persisted and over 120 descendant languages continue to be spoken today, making Vanuatu the per capita most linguistically diverse place on Earth.

Vanuatu therefore presents an unprecedented case, where a population's genetic ancestry but not its languages were replaced. Through analyses of new ancient and modern genome-wide data, the researchers show that rather than occurring in one wave, the genetic replacement was long and complex, likely the result of a sustained long-distance contact between Near and Remote Oceania. This provides demographic support for a model from historical linguistics, in which the initial Austronesian language of Vanuatu survived by being continually adopted by incoming Papuan migrants.

The Austronesian Expansion, which began around 5,500 years ago likely in modern-day Taiwan, was the most geographically extensive dispersal of farming peoples in prehistory, ultimately carrying people as far west as Madagascar and all the way east to Rapa Nui. These seafaring Neolithic people initially expanded out across Island Southeast Asia, carrying farming technology and a major branch of the Austronesian language family, eventually reaching Near Oceania where they encountered the indigenous Papuan peoples of New Guinea and the Bismarck Archipelago.

Dr. Frédérique Valentin excavating at Uripiv Island, Malakula, Vanuatu [Credit: Stuart Bedford]

The initial settlement east beyond the Solomon Islands and out into Remote Oceania only began around 3,000 years ago, with Austronesian-speaking groups associated with the Lapita pottery culture rapidly expanding east out to Vanuatu, New Caledonia, Fiji and the islands of Western Polynesia. A previous ancient DNA study of Lapita burial sites has shown that these earliest inhabitants had East Asian ancestry with negligible evidence of Papuan genetic admixture. But the present-day genetic make-up of Remote Oceania suggests at least some degree of Papuan ancestry, meaning there must have been subsequent Papuan migration and admixture into the Pacific from Near Oceania.

In order to understand this previously undescribed migration, a multidisciplinary team of researchers brought together different lines of evidence from the fields of genetics, archaeology and linguistics. They generated genome-wide data from the bones and teeth of 19 ancient individuals from across Vanuatu, Tonga, French Polynesia and the Solomon Islands, a significant addition to the ancient DNA record in a region whose environmental conditions generally leads to poor ancient DNA preservation.

As co-lead author Kathrin Nägele of the MPI-SHH says, "The identification of the petrous bone, which has recently been shown to provide fantastic aDNA preservation, has been a real game changer for such regions that were previously considered to be almost inaccessible." The ancient DNA was complemented by new contemporary genome-wide data from 27 present-day inhabitants of Vanuatu, collected as part of a long-term linguistic and anthropological fieldwork project run by co-authors Professor Russell Gray and Dr. Heidi Colleran of the MPI-SHH.

The ancient DNA provided direct evidence that Papuan people began arriving in Vanuatu soon after initial settlement by Austronesians. "We found a genetically Papuan-related individual dating to around 2,500 years ago in Vanuatu, far earlier than had been previously estimated using only modern genetic data," explains co-lead author Dr. Cosimo Posth, also of the MPI-SHH. The researchers were able to show that the ancestry of the initial Austronesian inhabitants of Vanuatu has been largely replaced by ancestry from Papuan peoples coming from the Bismarck Archipelago.

Maps showing the migrations in the area, including, in the final map, the migrations  revealed by the current study [Credit: Hans Sell, adapted from Skoglund et al. Genomic insights into the peopling of the Southwest Pacific. Nature (2016)]

But this genetic replacement was not straightforward, as Dr. Posth says, "Our analyses show that this replacement did not occur in a one-time mass migration event but rather happened incrementally over time, suggesting an enduring long-distance network between groups in Near and Remote Oceania." The authors also directly described ancient individuals with sex-biased admixture, where Papuan males intermixed with Austronesian women, as long assumed based on analyses of the modern genetic make-up of the South Pacific.

Yet despite this genetic replacement, the people of present-day Vanuatu continue to speak languages descended from those spoken by the initial Austronesian inhabitants rather than any Papuan language of the incoming migrants. As Professor Gray, Director of the Department of Linguistic and Cultural Evolution at the MPI-SHH, says, "Population replacement with language continuity is extremely rare -- if not unprecedented -- in human history.

The linguist Bob Blust has long argued for a model in which a separate Papuan expansion reaches Vanuatu soon after initial Austronesian settlement, with the initial, and likely undifferentiated, Austronesian language surviving as a lingua franca for diverse Papuan migrant groups." Dr. Adam Powell, senior author of the study and also of the MPI-SHH, continues, "The demographic history suggested by our ancient DNA analyses provides really strong support for this historical linguistic model, with the early arrival and complex, incremental process of genetic replacement by people from the Bismarck Archipelago. This provides a compelling explanation for the continuity of Austronesian languages despite the almost complete replacement of the initial genetic ancestry of Vanuatu."

The study in particular highlights the importance of interdisciplinary work and the value that multiple lines of evidence can have in deepening our understanding of human history. As Professor Johannes Krause, a senior author and Director of the Department of Archaeogenetics at the MPI-SHH, explains, "This multidisciplinary work has begun to uncover the complex, localized demographic processes that drove the initial colonization of the wider South Pacific and formed the enduring cultural and linguistic spheres that continue to shape the Pacific today." Ongoing engagement with local communities in Vanuatu, as well as with the Vanuatu Cultural Center, has been critical to this success.

As Dr. Colleran points out, "One strength of this study is the degree to which we are collaborating with communities in Vanuatu who have a real stake in these results and who generously volunteered their data to help answer these questions. We will be back in the field very soon to share the results with those communities and to hear their thoughts on the whole process." The progress of this continuing fieldwork can be followed on the Nature Ecology & Evolution Community website.

Source: Max Planck Institute for the Science of Human History [February 27, 2018]

While the giant birds that once dominated New Zealand are all extinct, a study of their preserved dung (coprolites) has revealed many aspects of their ancient ecosystem, with important insights for ongoing conservation efforts.

Moa skull [Credit: FunkMonk/WikiCommons]

Published in the Proceedings of the National Academy of Sciences, the study, by the University of Adelaide's Australian Centre for Ancient DNA (ACAD) and Landcare Research NZ, reconstructed the prehuman New Zealand ecosystem using coprolites ranging from 120 to 1500 years old.

The ancient dried dung originated from four species of extinct giant moa and the critically endangered kakapo parrot, and contained genetic records of diet, pathogens, and the behavior of the birds. Such detailed pictures of the pre-historic ecosystem are critical for present-day ecological restoration efforts, but are not available from the conventional fossil record of preserved skeletons.

The ancient dung samples were excavated from caves and rockshelters across New Zealand by Dr Jamie Wood, of Landcare Research. He says, "Coprolites were actually more common than we'd thought, once we started looking for them. And it turns out they contain a huge range of important information about past ecosystems."

Lead author Alex Boast, a PhD student at Landcare Research says, "A key finding was that the giant birds were eating a wide range of mushrooms and fungi, including species that are critical for the beech forests that are widespread across New Zealand. The brightly colored mushrooms remain distinctive parts of these forests today, but it appears they were meant to be eaten and then distributed by the moa.

"Worryingly, introduced mammals which consume these mushrooms don't appear to produce fertile spores, so this critical ecosystem function of the giant birds has been lost -- with serious implications for the long-term health of New Zealand's beech forests."

The research was performed at ACAD where Postdoctoral Research Associate and microbiome specialist, Dr Laura Weyrich, says, "Moa coprolites contained a surprising diversity of parasites, many completely new to science. Several parasites appear to be specialized to single moa species, so that a range of parasites became extinct with each moa species. As a result, we have probably underestimated the loss of biodiversity associated with the extinction of the megafauna."

ACAD Director, Professor Alan Cooper, who led the study, says, "The wide diversity of DNA we retrieved from the dung has allowed us to reconstruct many aspects of the behavior and interactions of species that we've never been able to see before. This important new method allows us to see how prehuman ecosystems have been altered, which is often hard to identify, and to guide our efforts in correcting some of the resulting damage."

Source: University of Adelaide [February 12, 2018]

The discovery of fossil insects, nematodes and fungi preserved in amber from sites in Otago is shedding new light on New Zealand's geological and biological history.

An image of a insect fossilized in amber [Credit: University of Otago]

University of Otago paleontologists Associate Professor Daphne Lee and Dr. Uwe Kaulfuss, with Professor Alexander Schmidt of the University of Göttingen, co-led a team of international scientists in collecting and analyzing amber deposits from more than 30 sites throughout New Zealand.

The small and fragile fossils are 25 to 15 million years old and include a number of spiders (including web remains with prey), tiny carnivores such as pseudoscorpions, diverse soil-dwelling mites, detritivores such as springtails, biting and gall midges, fungus gnats and chironomids, scale insects, parasitoid wasps, ants, beetles, and bark lice.

"Some of the arthropods and fungi represent the first fossil records of their groups from the entire Southern Hemisphere," Associate Professor Lee explains.

Hundreds of kilograms of amber were extracted from lignite deposits, largely near Roxburgh, Hyde and Pomahaka, in Otago. Preparation of the commonly opaque, and often brittle and/or fractured amber to expose inclusions for study is challenging. However, new techniques developed in Professor Schmidt's laboratory in Germany revealed numerous fossils with 3-D preservation.

The amber derives from the ancestors of the kauri, resin-producing conifers belonging to the Araucariaceae family which still live today in northern New Zealand.

"This means that the source of the resin has remained unchanged for at least the past 25 million years. The amber fossils help in understanding the evolution of these long-lasting forest ecosystems on a geologic time scale," Associate Professor Lee adds.

Amber, fossilized tree resin, preserves life forms, providing access to delicate organisms that are otherwise rare or absent from the fossil record.

Amber deposits are concentrated in the Northern Hemisphere where their inclusions have been studied intensively. Until now, the scarcity of major deposits from the Southern Hemisphere has severely hampered understanding of the global evolutionary history of terrestrial invertebrate and fungal biotas.

Dr. Kaulfuss says the fossils are significant because of what they tell us about the country's ecological history, as a long-isolated former Gondwanan landmass.

"These fossils are really important for us because they provide a very rare opportunity to look back on what made up New Zealand's forest and ecosystem 25 million-years-ago.

"We now know what kind of animals and plants were around at that time and what has gone extinct since then.''

The findings are published in Gondwana Research.

Source: University of Otago [February 08, 2018]