Nicotine extracted from ancient dental plaque for the first time

A team of scientists including researchers from Washington State University has shown for the first time that nicotine residue can be extracted from plaque, also known as "dental calculus," on the teeth of ancient tobacco users.

This is a 1945 picture of a Yokuts Native American woman smoking a pipe
[Credit: Clifford Relander]

Their research provides a new method for determining who was consuming tobacco in the ancient world and could help trace the use of tobacco and other intoxicating plants further back into prehistory.

"The ability to identify nicotine and other plant-based drugs in ancient dental plaque could help us answer longstanding questions about the consumption of intoxicants by ancient humans," said Shannon Tushingham, a WSU assistant professor of anthropology and co-author of a new study on the research in Journal of Archaeological Science Reports. "For example, it could help us determine whether all members of society used tobacco, or only adults, or only males or females."

A new source of information

Tracing the ancient spread of tobacco in the Americas has traditionally relied on the presence of pipes, charred tobacco seeds and the analysis of hair and fecal matter. However, these items are rare in the archeological record and are hard to link to particular individuals. As a result, tobacco use has been difficult to document archeologically.

On the other hand, dental plaque adheres to the surfaces of teeth and mineralizes over time, preserving a wide range of substances that are in the mouth. It is easy to link to particular individuals because it can be removed directly from teeth.

Nevertheless, dental plaque was largely ignored by archaeologists until recently.

However, using modern and highly sensitive instrumentation, scientists have found they can detect and characterize trace amounts of a wide variety of compounds, including proteins, bacterial DNA, starch grains and other plant fibers in dental plaque.

Because nicotine is detectable in the dental plaque of contemporary smokers, Tushingham and her collaborators wanted to find out if it also preserved in plaque taken from people who lived long ago.

She and David Gang, a professor in the WSU Institute of Biological Chemistry, Korey Brownstein, a graduate student in the WSU Molecular Plant Sciences Program, and Jelmer Eerkens, an anthropologist at the University of California, Davis, collaborated with members from the Ohlone tribe in San Francisco Bay to extract plaque from the teeth of eight individuals, buried between 6,000 and 300 years ago, and analyze it for nicotine.

Using ordinary dental picks, Eerkens and his team at UC Davis extracted the dental plaque from the ancient teeth and then sent it to Tushingham and Gang's labs at WSU for analysis. The WSU researchers used liquid chromatography-mass spectrometry to test the samples for nicotine and other plant-based drugs like caffeine and atropine, a muscle-relaxant.

Among the samples they analyzed, two tested positive for nicotine, demonstrating for the first time that the drug can survive in detectable amounts in ancient plaque. One of these individuals, an adult man, was also buried with a pipe. A surprise came from the molar of an older woman, which also tested positive for nicotine.

"While we can't make any broad conclusions with this single case, her age, sex, and use of tobacco is intriguing," Eerkens said. "She was probably past child-bearing age, and likely a grandmother. This supports recent research suggesting that younger adult women in traditional societies avoid plant toxins like nicotine to protect infants from harmful biochemicals, but that older women can consume these intoxicants as needed or desired."

While the researchers did not detect evidence of any other plant-based drugs in this particular study, they believe dental plaque could be used help trace the use and spread of other intoxicants as well.

"We think a wide variety of plant-based, intoxicating chemicals could be detected in ancient dental plaque," Brownstein said. "It really opens up a lot of interesting avenues of discovery."

Author: Will Ferguson | Source: Washington State University [February 27, 2018]

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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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Ancient genome study identifies traces of indigenous “Taíno” in present-day Caribbean populations

A thousand-year-old tooth has provided genetic evidence that the so-called "Taíno," the first indigenous Americans to feel the full impact of European colonisation after Columbus arrived in the New World, still have living descendants in the Caribbean today.

First encounter. Columbus landing in the New World [Credit: Library of Congress]

Researchers were able to use the tooth of a woman found in a cave on the island of Eleuthera in the Bahamas to sequence the first complete ancient human genome from the Caribbean. The woman lived at some point between the 8th and 10th centuries, at least 500 years before Columbus made landfall in the Bahamas.

The results provide unprecedented insights into the genetic makeup of the Taíno -- a label commonly used to describe the indigenous people of that region. This includes the first clear evidence that there has been some degree of continuity between the indigenous peoples of the Caribbean and contemporary communities living in the region today.

Such a link had previously been suggested by other studies based on modern DNA. None of these, however, was able to draw on an ancient genome. The new research finally provides concrete proof that indigenous ancestry in the region has survived to the present day.

Comparing the ancient Bahamian genome to those of contemporary Puerto Ricans, the researchers found that they were more closely related to the ancient Taíno than any other indigenous group in the Americas. However, they argue that this characteristic is unlikely to be exclusive to Puerto Ricans alone and are convinced that future studies will reveal similar genetic legacies in other Caribbean communities.

The findings are likely to be especially significant for people in the Caribbean and elsewhere who have long claimed indigenous Taíno heritage, despite some historical narratives that inaccurately brand them "extinct." Such misrepresentations have been heavily criticised by historians and archaeologists, as well as by descendant communities themselves, but until now they lacked clear genetic evidence to support their case.

The study was carried out by an international team of researchers led by Dr Hannes Schroeder and Professor Eske Willerslev within the framework of the ERC Synergy project NEXUS1492. The findings are published in the journal Proceedings of the National Academy of Sciences.

Lead author Schroeder, from the University of Copenhagen who carried out the research as part of the NEXUS1492 project, said: "It's a fascinating finding. Many history books will tell you that the indigenous population of the Caribbean was all but wiped out, but people who self-identify as Taíno have always argued for continuity. Now we know they were right all along: there has been some form of genetic continuity in the Caribbean."

Willerslev, who has dual posts at St John's College, University of Cambridge, and the University of Copenhagen, said: "It has always been clear that people in the Caribbean have Native American ancestry, but because the region has such a complex history of migration, it was difficult to prove whether this was specifically indigenous to the Caribbean, until now."

The researchers were also able to trace the genetic origins of the indigenous Caribbean islanders, showing that they were most closely related to Arawakan-speaking groups who live in parts of northern South America today. This suggests that the origins of at least some the people who migrated to the Caribbean can be traced back to the Amazon and Orinoco Basins, where the Arawakan languages developed.

The Caribbean was one of the last parts of the Americas to be populated by humans starting around 8,000 years ago. By the time of European colonization, the islands were a complex patchwork of different societies and cultures. The "Taíno" culture was dominant in the Greater, and parts of the Lesser Antilles, as well as the Bahamas, where the people were known as Lucayans.

To trace the genetic origins of the Lucayans the researchers compared the ancient Bahamian genome with previously published genome-wide datasets for over 40 present-day indigenous groups from the Americas. In addition, they looked for traces of indigenous Caribbean ancestry in present-day populations by comparing the ancient genome with those of 104 contemporary Puerto Ricans included in the 1000 Genomes Project. The 10-15% of Native American ancestry in this group was shown to be closely related to the ancient Bahamian genome.

Jorge Estevez, a Taíno descendant who works at the National Museum of the American Indian in New York and assisted the project team, said that as a boy growing up in the United States, he was told stories about his Taíno ancestors at home, but at school was taught that the same ancestors had died out. "I wish my grandmother were alive today so that I could confirm to her what she already knew," he added. "It shows that the true story is one of assimilation, certainly, but not total extinction. I am genuinely grateful to the researchers. Although this may have been a matter of scientific inquiry for them, to us, the descendants, it is truly liberating and uplifting."

Although indigenous Caribbean communities were island-based, the researchers found very little genomic evidence of isolation or inbreeding in the ancient genome. This reinforces earlier genetic research led by Willerslev, which suggests that early human communities developed surprisingly extensive social networks, long before the term had digital connotations. It also echoes ongoing work by researchers at the Faculty of Archaeology in Leiden and others indicating the connectedness of indigenous Caribbean communities.

Professor Corinne Hofman from Leiden University and PI of the NEXUS1492 project, said: "Archaeological evidence has always suggested that large numbers of people who settled the Caribbean originated in South America, and that they maintained social networks that extended far beyond the local scale. Historically, it has been difficult to back this up with ancient DNA because of poor preservation, but this study demonstrates that it is possible to obtain ancient genomes from the Caribbean and that opens up fascinating new possibilities for research."

Source: University of Cambridge [February 19, 2018]

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