Ancient DNA reveals genetic replacement despite language continuity in the South Pacific

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]

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Did humans speak through cave art? New paper links ancient drawings and language’s origins

When and where did humans develop language? To find out, look deep inside caves, suggests an MIT professor.

Stock image of a cave painting in South Africa [Credit: MIT]

More precisely, some specific features of cave art may provide clues about how our symbolic, multifaceted language capabilities evolved, according to a new paper co-authored by MIT linguist Shigeru Miyagawa.

A key to this idea is that cave art is often located in acoustic “hot spots,” where sound echoes strongly, as some scholars have observed. Those drawings are located in deeper, harder-to-access parts of caves, indicating that acoustics was a principal reason for the placement of drawings within caves. The drawings, in turn, may represent the sounds that early humans generated in those spots.

In the new paper, this convergence of sound and drawing is what the authors call a “cross-modality information transfer,” a convergence of auditory information and visual art that, the authors write, “allowed early humans to enhance their ability to convey symbolic thinking.” The combination of sounds and images is one of the things that characterizes human language today, along with its symbolic aspect and its ability to generate infinite new sentences.

“Cave art was part of the package deal in terms of how homo sapiens came to have this very high-level cognitive processing,” says Miyagawa, a professor of linguistics and the Kochi-Manjiro Professor of Japanese Language and Culture at MIT. “You have this very concrete cognitive process that converts an acoustic signal into some mental representation and externalizes it as a visual.”

Cave artists were thus not just early-day Monets, drawing impressions of the outdoors at their leisure. Rather, they may have been engaged in a process of communication.

“I think it’s very clear that these artists were talking to one another,” Miyagawa says. “It’s a communal effort.”

The paper, “Cross-modality information transfer: A hypothesis about the relationship among prehistoric cave paintings, symbolic thinking, and the emergence of language,” is published in the journal Frontiers in Psychology. The authors are Miyagawa; Cora Lesure, a PhD student in MIT’s Department of Linguistics; and Vitor A. Nobrega, a PhD student in linguistics at the University of Sao Paulo, in Brazil.

Re-enactments and rituals?

The advent of language in human history is unclear. Our species is estimated to be about 200,000 years old. Human language is often considered to be at least 100,000 years old.

“It’s very difficult to try to understand how human language itself appeared in evolution,” Miyagawa says, noting that “we don’t know 99.9999 percent of what was going on back then.” However, he adds, “There’s this idea that language doesn’t fossilize, and it’s true, but maybe in these artifacts [cave drawings], we can see some of the beginnings of homo sapiens as symbolic beings.”

While the world’s best-known cave art exists in France and Spain, examples of it abound throughout the world. One form of cave art suggestive of symbolic thinking — geometric engravings on pieces of ochre, from the Blombos Cave in southern Africa — has been estimated to be at least 70,000 years old. Such symbolic art indicates a cognitive capacity that humans took with them to the rest of the world.

“Cave art is everywhere,” Miyagawa says. “Every major continent inhabited by homo sapiens has cave art. … You find it in Europe, in the Middle East, in Asia, everywhere, just like human language.” In recent years, for instance, scholars have catalogued Indonesian cave art they believe to be roughly 40,000 years old, older than the best-known examples of European cave art.

But what exactly was going on in caves where people made noise and rendered things on walls? Some scholars have suggested that acoustic “hot spots” in caves were used to make noises that replicate hoofbeats, for instance; some 90 percent of cave drawings involve hoofed animals. These drawings could represent stories or the accumulation of knowledge, or they could have been part of rituals.

In any of these scenarios, Miyagawa suggests, cave art displays properties of language in that “you have action, objects, and modification.” This parallels some of the universal features of human language — verbs, nouns, and adjectives — and Miyagawa suggests that “acoustically based cave art must have had a hand in forming our cognitive symbolic mind.”

Future research: More decoding needed

To be sure, the ideas proposed by Miyagawa, Lesure, and Nobrega merely outline a working hypothesis, which is intended to spur additional thinking about language’s origins and point toward new research questions.

Regarding the cave art itself, that could mean further scrutiny of the syntax of the visual representations, as it were. “We’ve got to look at the content” more thoroughly, says Miyagawa. In his view, as a linguist who has looked at images of the famous Lascaux cave art from France, “you see a lot of language in it.” But it remains an open question how much a re-interpretation of cave art images would yield in linguistics terms.

The long-term timeline of cave art is also subject to re-evaluation on the basis of any future discoveries. If cave art is implicated in the development of human language, finding and properly dating the oldest known such drawings would help us place the orgins of language in human history — which may have happened fairly early on in our development.

“What we need is for someone to go and find in Africa cave art that is 120,000 years old,” Miyagawa quips.

At a minimum, a further consideration of cave art as part of our cognitive development may reduce our tendency to regard art in terms of our own experience, in which it probably plays a more strictly decorative role for more people.

“If this is on the right track, it’s quite possible that … cross-modality transfer helped develop a symbolic mind,” Miyagawa says. In that case, he adds, “art is not just something that is marginal to our culture, but central to the formation of our cognitive abilities.”

Author: Peter Dizikes | Source: Massachusetts Institute of Technology [February 21, 2018]

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Homo erectus may have sailed to islands and used language

They had bodies similar to modern humans, could make tools, and were possibly the first to cook. Now one expert is arguing that Homo erectus might have been a mariner – complete with sailing lingo.

Language was necessary for the spread of toolmaking technology, as well as for boat-building and sailing,
researchers suggest [Credit: Alamy Stock Photo]

Homo erectus first appeared in Africa more than 1.8m years ago and is thought to be the first archaic human to leave the continent.

H. erectus fossils have turned up not only in Southern Europe, but as far afield as China and Indonesia. Some argue that the mysterious hominid Homo floresiensis, discovered on the island of Flores, could be descended from H. erectus – although others disagree.

“Oceans were never a barrier to the travels of Erectus. He travelled all over the world, travelled to the island of Flores, across one of the greatest ocean currents in the world,” said Daniel Everett, professor of global studies at Bentley University, and author of How Language Began. “They sailed to the island of Crete and various other islands. It was intentional: they needed craft and they needed to take groups of twenty or so at least to get to those places.”

While Everett is not the first to raise the controversial possibility that H. erectus might have fashioned some sort of seagoing vessel, he believes that such capabilities mean that H. erectus must also have had another skill: language.

“Erectus needed language when they were sailing to the island of Flores. They couldn’t have simply caught a ride on a floating log because then they would have been washed out to sea when they hit the current,” said Everett, presenting his thesis at the meeting of the American Association for the Advancement of Science in Austin. “They needed to be able to paddle. And if they paddled they needed to be able to say ‘paddle there’ or ‘don’t paddle.’ You need communication with symbols not just grunts.”

It is unknown when language emerged among hominids; some argue that it is a feature only of our own species, Homo sapiens, which suggests a timing of no earlier than 200,000 years ago. But Everett believes it goes back further than that.

Everett says that H. erectus would have been unable to make the same range of sounds as we do, not least because they lacked the version of a gene necessary for speech and language to develop – known as FOXP2 – found in modern humans and Neanderthals, although it is not clear whether Neanderthals had language. But he argues that as few as two sounds are needed for a language, and that it is likely H.erectus could make more than that.

“They had what it took to invent language – and language is not as hard as many linguists have led us to believe. If you have symbols in a linear order then you have a grammar,” said Everett. “Homo erectus spoke and invented the Model T Ford of language. We speak the Tesla form, but their Model T form was not a proto-language it was a real language.”

“Everybody talks about Homo erectus as a stupid ape-like creature, which of course describes us just as well, and yet what I want to emphasise is that Erectus was the smartest creature that had ever walked the Earth,” he said.

The theory received mixed reactions from others. Kevin Laland, professor of behavioural and evolutionary biology at the University of St Andrews, said he agreed with Everett. “The important thing to recognise is that language did not appear in modern form all at once, but gradually evolved from a protoculture comprising just a handful of words with little grammatical structure. Certainly, it is highly plausible that Homo erectus had a protolinguistic capability,” he said, adding that work by his own team hinted it was possible. “Our experiment suggests that it would have been very difficult for knowledge of how to manufacture Homo erectus’s Acheulian stone tools to spread without a simple form of language. The study also demonstrates that stone toolmaking would had created a selection pressure favouring increased linguistic capabilities,” he said.

But others say that there is little evidence that H. erectus was a sophisticated seafarer, let alone had a language. “I don’t accept that, for example, [Homo] erectus must have had boats to get to Flores,” said Chris Stringer, head of human origins at the Natural History Museum in London. “Tsunamis could have moved early humans on rafts of vegetation.”

That said, Stringer notes that Homo heidelbergensis, another extinct relative of ours that lived between 700,000 and 300,000 years ago, might have been capable of some sort of chat. “I think [Homo] heidelbergensis had a complex enough life to require speech, though not at the level of modern human language. With [Homo] erectus, I’m not so sure,” said Stringer, adding that the ability of H. erectus to make and use tools is not, as some have argued, convincing evidence. “Chimps and crows make and use tools without a human kind of language,” he said.

Author: Nicola Davis | Source: The Guardian [February 20, 2018]

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Interdisciplinary approach yields new insights into human evolution

The evolution of human biology should be considered part and parcel with the evolution of humanity itself, proposes Nicole Creanza, assistant professor of biological sciences. She is the guest editor of a new themed issue of the Philosophical Transactions of the Royal Society B, the oldest scientific journal in the world, that focuses on an interdisciplinary approach to human evolution.

Credit: iStock

Stanford professor Marc Feldman and Stanford postdoc Oren Kolodny collaborated with Creanza on the special issue.

"Within the blink of an eye on a geological timescale, humans advanced from using basic stone tools to examining the rocks on Mars; however, our exact evolutionary path and the relative importance of genetic and cultural evolution remain a mystery," said Creanza, who specializes in the application of computational and theoretical approaches to human and cultural evolution, particularly language development. "Our cultural capacities-to create new ideas, to communicate and learn from one another, and to form vast social networks-together make us uniquely human, but the origins, the mechanisms, and the evolutionary impact of these capacities remain unknown."

The special issue brings together researchers in biology, anthropology, archaeology, economics, psychology, computer science and more to explore the cultural forces affecting human evolution from a wider perspective than is usually taken.

"Researchers have begun to recognize that understanding non-genetic inheritance, including culture, ecology, the microbiome, and regulation of gene expression, is fundamental to fully comprehending evolution," said Creanza. "It is essential to understand the dynamics of cultural inheritance at different temporal and spatial scales, to uncover the underlying mechanisms that drive these dynamics, and to shed light on their implications for our current theory of evolution as well as for our interpretation and predictions regarding human behavior."

In addition to an essay discussing the need for an interdisciplinary approach to human evolution, Creanza included an interdisciplinary study of her own, examining the origins of English's contribution to Sranan, a creole that emerged in Suriname following an influx of indentured servants from England in the 17th century.

Creanza, along with linguists Andre Sherriah and Hubert Devonish of the University of the West Indes and psychologist Ewart Thomas from Stanford, sought to determine the geographic origins of the English speakers whose regional dialects formed the backbone of Sranan. Their work combined linguistic, historical and genetic approaches to determine that the English speakers who influenced Sranan the most originated largely from two counties on opposite sides of southern England: Bristol, in the west, and Essex, in the east.

"Thus, analyzing the features of modern-day languages might give us new information about events in human history that left few other traces," Creanza said.

Author: Liz Entman | Source: Vanderbilt University [February 13, 2018]

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