Fossil Finger Points to New Human Species DNA Analysis Reveals Lost Relative from 40,000 Years Ago

Vol 464|25 March 2010 NEWS Fossil finger points to new human species DNA analysis reveals lost relative from 40,000 years ago.

In the summer of 2008, Russian researchers it. It sounded too fantastic to be true.” dug up a sliver of human finger bone from an Researchers not involved in the work isolated Siberian cave. The team stored it away applauded the findings but cautioned against for later testing, assuming that the nondescript drawing too many conclusions from a single fragment came from one of the Neanderthals study. “With the data in hand, you cannot who left a welter of tools in the cave between claim the discovery of a new species,” says Eske 30,000 and 48,000 years ago. Nothing about Willerslev, an evolutionary biologist and the bone shard seemed extraordinary. director of the Centre for GeoGenetics at the Its genetic material told another story. When University of Copenhagen. German researchers extracted and sequenced If further work does support the initial A finger bone found in Denisova Cave in Siberia could add a DNA from the fossil, they found that it did not conclusions, the discovery would mark the branch to the human family tree. match that of Neanderthals — or of modern first time that an extinct human relative had humans, which were also living nearby at the been identified by DNA analysis. It would time. The genetic data, published online in also suggest that ice-age humans were more possibility that several Homo species ranged Nature1, reveal that the bone may belong to diverse than had been thought. Since the late across Europe and Asia, overlapping with the B. Viola B. a previously unrecognized, extinct human nineteenth century, researchers have known direct ancestors of modern people. species that migrated out of Africa long before that two species of Homo — Neanderthals and The Siberian site in the Altai Mountains, our known relatives. modern humans — coexisted during the later called Denisova Cave, was already known as a “This really surpassed our hopes,” says Svante part of the last ice age. In 2003, a third species, rich source of Mousterian and Levallois artefacts, Pääbo, senior author on the international study Homo floresiensis, was discovered on the island two styles of tool attributed to Neanderthals. For and director of evolutionary genetics at the Max of Flores in Indonesia, but there has been no more than a decade, Russian scientists from the Planck Institute for Evolutionary Anthropology sign of this tiny ‘hobbit’ elsewhere. The rela- Institute of Archaeology and Ethnology in Nov- in Leipzig, Germany. “I almost could not believe tive identified in Siberia, however, raises the osibirsk have been searching for the toolmakers’ Teams set for first taste of Antarctic lakes

The pitch-black lakes hidden of the lakes could resemble able to explore a continental-scale Antarctic field season, but their beneath Antarctica’s ice sheet conditions on Jupiter’s moon ecosystem that has never before drill got stuck 80 metres above will finally start to release their Europa, which is assumed to hold been sampled,” says Robin Bell, the lake surface. All technical secrets next year. At a meeting last a large ocean beneath its frozen a senior researcher at Columbia problems have been resolved week, scientists from Russia, the surface. University’s Lamont-Doherty during the past field season, United Kingdom and the United Scientists have longed to Earth Observatory in Palisades, says Valery Lukin, director of the States described their plans to draw samples New York. “This is Russian Antarctic programme, WATER BELOW THE ICE explore the planet’s last uncharted from the lakes, “It’s like going fishing a madly exciting who spoke at the meeting, held by Three countries plan to drill through the Antarctic ice sheet to explore ecosystems by drilling into three but technical in the Everglades, in the endeavour.” the American Geophysical Union hidden lakes. Russian researchers very different examples of these problems and Rocky Mountains and in Lake Vostok is in Baltimore, Maryland. hope to reach Lake Vostok next year. subglacial lakes. environmental the best known Some researchers worry that Antarctic Northern Canada.” ice sheet Drill Over the past 40 years, radar concerns have and largest of a Russian success could come ANTARCTICA imagery has revealed around slowed their progress. Now, the the subglacial lakes, measuring at the cost of biological and Frozen lake water 4 km 150 freshwater lakes of various Russian team expects to reach its roughly the size of Lake Ontario. chemical contamination of the Ellsworth sizes and ages beneath the quarry, Lake Vostok, by February Buried beneath almost 4,000 pristine waters. “Let’s hope they Lake Vostok Vostok massive Antarctic ice sheet. 2011. The Americans and British metres of ice in eastern Antarctica, don’t spoil the lake,” says Robert Whillans Some have been isolated from the will follow several years later with the lake is thought to be 35 million Bindschadler, a glaciologist at Ross Ice Shelf outside world for millions of years, forays into lakes with different years old and could host ancient NASA’s Goddard Space Flight raising the possibility that they hydrological and geological microbial life. Center in Greenbelt, Maryland. hold unique life forms. The dark, characteristics (see graphic). Russian drillers had planned to Lukin says that his country’s nutrient-deprived environment “Over the next few years we’ll be penetrate the lake in the 2008–09 team has come up with plans to

Bizarre models l Plants shed light on disfigured faces, and yeast hints at blood-vessel growth. ND SYRED/SP ND

go.nature.com/p96Oe9 a WER o bones. They discovered several bone specimens, in a previously unknown migration, between nuclear DNA will properly define the position of P handling each potentially important new find that of Homo erectus 1.9 million years ago and the Siberian relative in the human family tree. with gloves to prevent contamination with mod- that of the Neanderthal ancestor Homo heidel- Anthropologists also want to see more- ern human DNA. The bones’ own DNA could bergensis, 300,000 to 500,000 years ago. refined dating of the sediments and a better then be extracted and analysed. Study author Johannes Krause, also at the description of the finger bone itself. “I haven’t When the finger bone was discovered, “we Max Planck Institute in Leipzig, says that the seen a picture of the bone, and would like to,” didn’t pay special attention to it”, says archae- researchers are now generating nuclear DNA says Owen Lovejoy, an anthropologist at Kent ologist Michael Shunkov of the Novosibirsk sequences from the bone with the hope of State University in Ohio. “The stratigraphic age institute. But Pääbo had established a rela- sequencing its entire genome. If they are suc- for the bone is 30,000 to 48,000 years old, but tionship with the Russian team years before to cessful, it would be the oldest human genome the mtDNA age could be as old as H. erectus,” gather material for genetic testing from ice-age sequenced, eclipsing that of says Lovejoy. “That doesn’t humans. After obtaining the bone, the German the 4,000-year-old Eskimo “I almost could not tell us much about human team extracted the bone’s genetic material and from Greenland that Will- believe it. It sounded too evolution unless it truly rep- sequenced its mitochondrial DNA (mtDNA) erslev and his colleagues fantastic to be true.” resents a surviving ancient — the most abundant kind of DNA and the reported last month2. species.” best bet for getting an undegraded sequence A complete genome might also enable the The cave has yielded few clues about the from ancient tissue. researchers to give the proposed new species culture of the Siberian hominin, although a After re-reading the mtDNA sequences a formal name. They had originally planned fragment of a polished bracelet with a drilled an average of 156 times each to ensure accu- to do so on the basis of the mtDNA genome. hole was found earlier in the same layer that racy, the researchers compared them with the But they opted to wait until more bones are yielded the bone3. mtDNA genomes of 54 modern humans, a found — or until the DNA gives a clearer pic- Pääbo suspects that other human ancestors — 30,000-year-old modern human found in Rus- ture of its relationship to modern humans and and new mysteries — may emerge as geneticists sia and six Neanderthals. The Denisova Cave Neanderthals. grind up more ancient bones for sequencing. DNA fell into a class of its own. Although a Willerslev emphasizes that, on its own, “It is fascinating that molecular studies make Neanderthal mtDNA genome differs from that the mtDNA evidence does not verify that the a contribution in palaeontology where there is of Homo sapiens at 202 nucleotide positions on Siberian find represents a new species because little or no morphology preserved,” he says. “It average, the Denisova Cave sample differed at mtDNA is inherited only from the mother. It is is clear we stand just in the beginning of many an average of 385 positions. possible that some modern humans or Nean- fascinating developments.” ■ The differences imply that the Siberian derthals living in Siberia 40,000 years ago had Rex Dalton ancestor branched off from the human family unusual mtDNA, which may have come from tree a million years ago, well before the split earlier interbreeding among H. erectus, Nean- 1. Krause, J. et al. Nature doi:10.1038/nature08976 (2010). 2. Rasmussen, M. et al. Nature 463, 757–762 (2010). between modern humans and Neanderthals. derthals, archaic modern humans or another, 3. Derevianko, a., Shunkov, M. & Volkov, P. Archaeol. Ethnol. If so, the proposed species must have left Africa unknown species of Homo. Only probes of the Anthropol. Eurasia 34, 13–25 (2008).

safeguard Lake Vostok. The team into the lake to explore the bottom requirement for the team to wait plans to drill into the lake during will cut through the ice using a sediment will be postponed until then. “The Russians are the 2012–13 field season. heated drill, with non-toxic silicone until an extra environmental trying very hard to do it right, and Lake Whillans has a subsurface oil serving as the lubricating fluid. assessment has been completed. that means a lot,” says Bell. connection with the ocean beneath It will also explore the lake in The Antarctic Treaty’s At the meeting, US and British the ice shelf, making it more stages; at first it will only suck up committee for environmental researchers described their dynamic than isolated lakes such a water sample before allowing protection is expected to approve longer-term plans for exploring as Vostok. “We know that the lake the bottom of the hole to refreeze. the Russian plans in October, subglacial lakes on the opposite surface is constantly falling and Plans for lowering instruments although there is no official side of the pole. Lake Ellsworth, rising, and we assume the lake is a relatively small lake in western occasionally draining and refilling WATER BELOW THE ICE Antarctica, is the target for completely,” says Powell. Three countries plan to drill through researchers from the British The ebb and flow of lakes the Antarctic ice sheet to explore hidden lakes. Russian researchers Antarctic Survey. And over such as Whillans are thought to hope to reach Lake Vostok next year. the next two field seasons, influence the movement of the Antarctic ice sheet Drill US researchers will conduct overlying ice sheet. The WISSARD ANTARCTICA radar surveys from the team will study processes at the Frozen surface to study Lake interface of ice and water that lake water 4 km Ellsworth Whillans near Antarctica’s affect the movement. Lake Ross Ice Shelf, says Ross With so many drilling projects, Vostok Vostok Whillans Powell, a geologist at Northern “it’s like going fishing in the Ross Ice Shelf Illinois University in DeKalb. Everglades, in the Rocky Mountains The US$20-million Whillans and in Northern Canada”, says Bell. Ice Stream Subglacial Access “The catch will be very different Research Drilling (WISSARD) and we’re going to learn a lot.” ■ project, which Powell oversees, Quirin Schiermeier