Migration to Americas Traced Genomes Show That the Americas’ Earliest Settlers Moved Far and Fast Across the Continent

president. She says that the group spent US$2 million during this election cycle on items such as ads and voter-registration drives, and contributed another $250,000 to various candidates’ campaigns. That wave of interest is “indicative of people’s desire to get involved, and a recognition that it’s no longer okay to sit on the sidelines”, says

TOM WILLIAMS/CQ ROLL CALL/GETTY TOM Benjamin Corb, director of public affairs at the American Society for Biochemistry and Molec- ular Biology in Rockville, Maryland. The victories for science candidates came as Democrats regained a majority of seats in the House, taking the chamber back from Repub- licans — who still control the Senate and the White House. Recapturing the House is “no small feat”, says Elizabeth Gore, senior vice- president for political affairs at the Environmen- tal Defense Fund, an advocacy group in New York City. “It is going to change the dialogue in Washington, and will certainly change the Eddie Bernice Johnson (left) is in line to become the next leader of the House science committee. dynamic around science and the environment.” interest in science who will exit Congress at the the Trump administration’s policies. Gore says A CHANGING CLIMATE end of year. Voters rejected a bid for re-election that this is likely to translate into congressional One of the most dramatic transitions will by Representative John Culberson of Texas, a hearings that probe the administration’s efforts involve the House Committee on Science, space enthusiast who leads the House spend- to roll back a variety of climate and environ- Space and Technology. Representative Eddie ing panel that oversees NASA, the National mental regulations, and explore whether they Bernice Johnson, a Texas Democrat and vocal Science Foundation and the National Oceanic are justified by the available science. critic of the Trump administration, is likely and Atmospheric Administration. Culberson’s “Some of the oversight that we will see in to take the helm from retiring Representative stalwart support for a NASA mission to Jupiter’s a Democratic House will be focused on re- Lamar Smith (Republican, Texas). As chair, moon Europa became a campaign issue after his establishing scientific integrity and highlight- Smith has repeatedly questioned the science opponent accused him of favouring pet projects ing the failure of the Trump administration to behind climate change, sought to pare back the and neglecting local issues in his district near use scientifically based information for policy- National Science Foundation’s research portfo- Houston. making,” Gore adds. lio and launched dozens of probes into alleged Culberson is “probably the strongest sup- Others worry that with Democrats taking the wrongdoing by individual scientists and US porter of planetary science, maybe in history”, House and Republicans solidifying their major- government science agencies. says Casey Dreier, senior policy adviser at the ity in the Senate, political gridlock will worsen By contrast, Johnson released a list of policy Planetary Society in Pasadena, California. “It in the coming years. “The polarization in the priorities on 6 November that includes fighting was so neat to see someone in Congress who Congress has increased,” says Robert Stavins, an climate change — “starting with acknowledg- had a personal passion for the search for extra- environmental economist at Harvard Univer- ing it is real” — and making the science panel terrestrial life.” sity in Boston, Massachusetts. “What was left of “a place where science is respected”. Holding even a slim margin in the House moderate Republicans — those are the people Smith is not the only Republican with a strong will give Democrats the power to investigate who systematically lost to Democrats.” ■

ANCIENT GENOMICS Migration to Americas traced Genomes show that the Americas’ earliest settlers moved far and fast across the continent.

BY EWEN CALLAWAY America within 1,000–2,000 years by related “I think this series of papers will be groups. Later migrations on and between the remembered as the first glimpse of the real ncient genomics is finally beginning to continents connected populations living as far complexity of these multiple peopling events,” tell the history of the Americas — and apart as California and the Andes. says Ben Potter, an archaeologist at the it’s looking messy. “These early populations are really blasting University of Alaska Fairbanks. “It’s awesome.” AGenomes from dozens of ancient inhabit- across the continent,” says David Meltzer, an For decades, the peopling of the Americas ants of North and South America, who lived archaeologist at Southern Methodist University was painted in broad brushstrokes, using data as much as 11,000 years ago, suggest that in Dallas, Texas, who co-led one study2. from archaeological finds and DNA from mod- the populations moved fast and frequently. The studies also suggest that the prehistory ern humans. Scientists discerned that groups The findings, published on 8 November1,2, of the Americas — the last major land mass to crossed the Bering land bridge from Siberia indicate that North America was populated be settled — was just as convoluted as that of into present-day Alaska, and then moved stead- widely over a few hundred years, and South other parts of the world. ily south as the last ice age ended. Humans

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despite the great geographical distances between them, Willerslev says, pointing to a rapid population expansion from Alaska. “As soon as they get south of the continental ice caps, they’re exploding and occupying the land,” he says. An independent team led by David Reich, a population geneticist at Harvard Medi- cal School in Boston, Massachusetts, also found evidence1 for a rapid expansion into South America, through analysing 49 ancient genomes from Central and South Americans. Both teams documented multiple later human migrations into South America. Reich’s group found, for instance, that the genetic signal CAROLINA BIOLOGICAL SUPPLY CO./VISUALS UNLIMITED/SPL CO./VISUALS SUPPLY CAROLINA BIOLOGICAL of the earliest inhabitants — closely related to the Anzick boy — had largely vanished from later South Americans, suggesting that different An arrowhead that belonged to people associated with the Clovis culture, early settlers in the Americas. groups had by then moved in from the north. Potter says that the main conclusions of the carrying artefacts, such as sophisticated pro- the common ancestor of those two groups split two papers are broadly consistent. “Complex jectile points, from a culture known as Clovis from East Asians some 25,000 years ago, as sci- and realistic are the two adjectives I would use,” began to populate the interior of North America entists established earlier this year by sequenc- he says. about 13,000 years ago. For decades, scientists ing the genome of 11,500-year-old human Even with dozens more newly discovered thought that people associated with this culture remains from Alaska5. ancient genomes from the Americas, impor- were the continents’ first inhabitants. But this timeline was based on just a few tant aspects of the region’s population history But the discovery of ‘pre-Clovis’ settlements ancient genomes from the Americas, and sci- are probably still missing, says Reich. “There — including a nearly 15,000-year-old site at entists expected further data to paint a more are many dots that are not filled in,” he says. the southern tip of Chile — pointed to an even detailed, complex picture of the continents’ “I think as these studies scratch the surface, earlier wave of migration to the Americas. history, as well as reveal later migrations there. they make things more, rather than less, The first ancient-DNA studies from the complicated.” region, appearing in 2014, began to add detail SAME GENES, FAR APART Jennifer Raff, an anthropological geneticist to this picture. The genome of a baby boy who The two latest studies include genome data at the University of Kansas in Lawrence, says was buried roughly 12,700 years ago in Montana from 64 ancient Americans, and provide the that the emerging picture of the Americas is alongside Clovis artefacts3, and genomes from first detailed look at the ancient inhabitants less a revision of the earlier models and more other ancient individuals4, hinted at two early of Central and South America and their early an elaboration. “It’s not that everything we populations of Native Americans. movements into the region. know is getting overturned. We’re just filling The Montana baby, known as the Anzick boy, To chart these migrations, Meltzer and his in details,” she says. ■ belonged to a population known as the South- colleague Eske Willerslev, a palaeogeneticist at 1. Posth, C. et al. Cell https://doi.org/10.1016/j. ern Native Americans, who are most closely the Natural History Museum of Denmark in cell.2018.10.027 (2018). related to present-day Indigenous populations Copenhagen, compared genetic data from the 2. Moreno-Mayar, J. V. et al. Science https://doi. from South America. They split from Northern Anzick boy with those from 10,700-year-old org/10.1126/science.aav2621 (2018). 3. Rasmussen, M. et al. Nature 506, 225–229 (2014). Native Americans, who are genetically closer to remains in a Nevada cave and 10,400-year-old 4. Rasmussen, M. et al. Nature 523, 455–458 (2015). many contemporary groups in eastern North remains from southeastern Brazil. 5. Moreno-Mayar, J. V. et al. Nature 553, 203–207 America, around 14,600–17,500 years ago. And The genomes were remarkably similar, (2018).

INSTITUTIONS enough people, and that its scope may have been too narrow. Its members, who say they are among 12 people who contributed evidence to the April complaint that prompted the probe, Sanger whistle-blowers also question the investigation’s transparency. Their concerns “cast doubt as to whether the investigation was conducted in a man- dispute inquiry findings ner that was as effective as it could be, given the seriousness of the allegations”, they say in Leading genomics institute stands by conclusions of an a statement seen by Nature. On 2 November, investigation that clears its management of bullying. Serena Nik‑Zainal, a clinical scientist who now works at the University of Cambridge, sent the statement to Genome Research Limited BY HOLLY ELSE bullying, gender discrimination and misuse of (GRL), which oversees the Sanger and commis- grant money. sioned the investigation from barrister Thomas ix current and former employees are The group raises concerns about the process Kibling. “We firmly believe sufficient evidence calling for the Wellcome Sanger Institute of the investigation and questions the decision was not unearthed to make an appropriate in Hinxton, UK — one of the world’s top to clear senior management at the institute of judgement,” says the statement. Sgenomics centres — to reopen an investiga- the allegations. Among other things, the group David Willetts, chair of the board of GRL, told tion that last month cleared its management of says that the investigation did not interview Nature that the investigation was independent