News this Week

Science  09 Sep 2011:
Vol. 333, Issue 6048, pp. 1364

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  1. Around the World

    1 - Stirling, U.K.
    Tobacco Firm Seeks Study Data On Young Smokers' Habits
    2 - Petrified Forest, Arizona
    New Growth for Fossil Forest
    3 - Reykjavík
    Iceland's Avalanche Funds Redirected to Study Volcano Risk
    4 - Washington, D.C
    Captive Chimps: ‘Endangered’?
    5 - Ankara, Turkey
    Turkish Government Takes Control of Academy

    Stirling, U.K.

    Tobacco Firm Seeks Study Data On Young Smokers' Habits

    Scottish researchers are protesting an attempt by Philip Morris, the world's largest tobacco company, to obtain what they consider confidential information on the smoking habits of British teenagers. Using the Scottish Freedom of Information Act, the company has requested that the University of Stirling provide information, which includes thousands of interviews with teenagers, obtained in a research project funded by the charity Cancer Research UK. “These kids have been reassured that only bona fide researchers will have access to their data. No way can Philip Morris fit into that definition,” Gerard Hastings, director of the university's Institute for Social Marketing, told The Independent, a British newspaper. Some of the study material may provide insight into how teenagers would react to a cigarette pack devoid of branding, which the United Kingdom is considering mandating. The tobacco firm says it is not seeking the names of the study participants or any other confidential information, but that it has a legitimate interest in the study and its requests are legal.

    Petrified Forest, Arizona

    New Growth for Fossil Forest

    Fossil full.

    Late Triassic fossils abound in Arizona's badlands.


    Arizona's Petrified Forest National Park may get a big boost in future fossil finds, thanks to the addition 8 September of 11,000 hectares of once-private land likely to be rich in Late Triassic fossils. The deal between the owners and the National Park Service, 11 years in the making, was brokered by Virginia-based nonprofit organization The Conservation Fund. The park previously spanned 38,000 hectares in total, but the park lands were interspersed with private lands, which hindered cohesive and sustainable management of the resources, says Mike Ford, southwest director of The Conservation Fund. The new acquisition increases the park size by a third, with large blocks intact, Ford says.

    The badlands that cross through the park are replete with fossils of phytosaurs, distant ancestors of both dinosaurs and crocodiles, as well as with early dinosaurs and ancient plants, says National Park Service paleontologist Bill Parker. The acquisition is “going to add immensely to figuring out the story of the park and Late Triassic paleontology in general,” he says.


    Iceland's Avalanche Funds Redirected to Study Volcano Risk


    In late August, Iceland's parliament approved a resolution to allow Iceland's Meteorological Office, which is responsible for forecasting natural hazards, to shift more of its focus from avalanches to volcanoes. The office will initially devote an estimated $2 million over the first 3 years to kickstart the project.

    Iceland created a risk assessment fund for avalanches following two avalanches that killed 34 people in 1995. As a result, there are now around 30 risk assessment specialists in the country—about 10 of whom still work on avalanches, says Sigrún Karlsdóttir, chief of natural hazards at the Icelandic Meteorological Office.

    Karlsdóttir estimates the volcano risk assessment will develop over 15 to 20 years. During the first 3 years of the plan, scientists will identify Iceland's active volcanoes, analyze data from existing volcano monitoring stations, and find gaps in the coverage. Researchers will also identify where lava might interfere with human habitation or infrastructure, much as the avalanche risk assessment does, and develop evacuation plans.

    Washington, D.C

    Captive Chimps: ‘Endangered’?

    The U.S. Fish and Wildlife Service (FWS) has initiated a review of whether it should “uplist” the status of captive chimpanzees from “threatened” to “endangered.” A 144-page petition spearheaded by the Humane Society of the United States (HSUS) and endorsed by seven other groups wants the status changed to grant better protections under the Endangered Species Act for the country's estimated 2150 captive chimpanzees.

    Much of the petition focuses on the “sanctioned exploitation” of chimpanzees by the entertainment industry and the keeping of pet chimps. But nearly half the captive population consists of chimps in biomedical research laboratories.

    The uplisting “would have no impact on the preservation of wild chimpanzees,” contends John VandeBerg, who directs the Southwest National Primate Research Center in San Antonio, Texas, which conducts biomedical research with chimpanzees. VandeBerg says endangered status would hamper breeding of research chimps, which could become critical to preservation of the species if they become extinct in the wild.

    A similar petition led FWS in 1990 to raise the status of wild chimpanzees to endangered, but left captive ones as threatened. This unusual split listing is “scientifically unjustifiable,” the petition contends.

    Ankara, Turkey

    Turkish Government Takes Control of Academy

    Members of the Turkish Academy of Sciences (TÜBA) are up in arms about a government decree that strips the academy of its autonomy. They are threatening to resign en masse and form a new academy if the measure isn't reversed.

    Among other things, the 27 August law stipulates that from now on, the Turkish government and the Council of Higher Education, which is controlled by the government, will each elect one-third of the academy's members, while the government will also appoint its president. (Currently, academy members elect new members and their president.) “This is interfering with the independence of the academy, thus destroying [its] most important aspect,” TÜBA President Yücel Kanpolat writes in an e-mail. Kanpolat says the move is part of a campaign by the government to tighten its grip on Turkish society.

    The International Human Rights Network of Academies and Scholarly Societies has asked Turkish Prime Minister Recep Erdoǧan to “quickly reverse the legislation.”

  2. Newsmakers

    Three Q's



    Boarding an airplane could be speedier thanks to Jason Steffen, an astrophysicist at Fermi National Accelerator Laboratory in Batavia, Illinois. Three years ago Steffen figured out the fastest way to load a plane, and now he and filmmaker Jon Hotchkiss have tested the method in a pilot for a proposed television show. Steffen's method was twice as fast as row or zone boarding, they report in a paper submitted to the Journal of Air Transport Management.

    Q:So how does the algorithm work?

    Adjacent passengers in the line should be 12 seats apart [counting row by row from the back of a plane with six seats per row]. That limits interferences in which passengers get stuck behind one another in the aisle and eliminates the seat interferences in which passengers have to move past one another in a row. The algorithm, Markov chain optimization, is used all the time in physics and astrophysics.

    Q:Were you apprehensive about making the television pilot?

    Jon contacted me and asked if I would answer a couple of questions. And I said, “I'll do more than answer questions, I'll help you make the film.” This kind of project shows the usefulness of having technically educated people in society.

    Q:Do you think your method will be employed?

    Could be employed? I'd say yes. Will be employed? That's not my decision. It takes some time to get people lined up, but there's nothing preventing you from doing that while you can't get on the airplane anyway.

  3. Random Sample

    For Want of a Wolf, the Lynx Was Lost?


    The Canadian lynx (Lynx canadensis) is thriving in Canada but is a threatened species in the United States. The chain of events that led to the mysterious decline of lynxes in the United States, scientists now say, may have begun with the extirpation of another species: the gray wolf (Canis lupus), which was hunted to near extinction in the United States during the 20th century. Today, wolf populations are growing in parts of the west and Minnesota.

    The loss of the wolf may have set in motion an “ecological cascade,” William Ripple, an ecologist at Oregon State University, Corvallis, and his co-authors write 30 August in Wildlife Society Bulletin. Without wolves, populations of coyotes and herbivores (such as elk and deer) have soared—leading to a double whammy for the lynx's primary prey, the snowshoe hare (Lepus americanus). First, there are more coyotes to hunt them; and second, elk and deer consume the shrubby cover hares eat and seek for protection from predators. The result: fewer snowshoe hare for the lynx to hunt. Climate change may be another factor; snowshoe hare and lynxes thrive at high elevations with deep snow packs, but milder winters open up these areas to coyotes.

    Since their reintroduction to Yellowstone National Park in 1995, wolves have sharply curtailed the coyote population, altered the behavior of both coyotes and herbivores, upped the number of snowshoe hare, and helped restore overall ecosystem health, the authors say. So wildlife managers should consider wolves' “ecological role”—and value as top dog—when deciding their fate.

    By the Numbers

    $110,000 — Amount that a California science center, which canceled a showing of the intelligent design film Darwin's Dilemma in 2009, has to pay to conservative group American Freedom Alliance under terms of a settlement reached 29 August.

    $63.2 billion — Amount per year that insomnia is costing the U.S. workforce, according to study published 1 September in SLEEP.

  4. Paleoanthropology

    Skeletons Present an Exquisite Paleo-Puzzle

    1. Ann Gibbons

    Partial skeletons of 2-million-year-old hominin Australopithecus sediba leave researchers impressed by their completeness but scratching their heads over the implications for our family tree.


    Lee Berger (left), his son Matthew, and dog Tau visit the pit at Malapa.


    At a recent meeting, hominin expert Leslie Aiello found herself stymied. She was examining casts of the hand, arm, and foot of a recently discovered member of the human family, Australopithecus sediba, and what she saw puzzled her. The foot looked like that of an extinct ape, but the ankle joint was like a human's. If she had seen the parts separately, she would never have guessed that they belonged to the same 2-million-year-old individual. “The foot is so weird,” says Aiello, president of the Wenner-Gren Foundation for Anthropological Research in New York City. “Nobody expected this thing.”

    Aiello isn't the only scientist surprised by the appearance of Au. sediba, which is described in detail in five papers starting on page 1402 of this issue. An international team of researchers, led by paleoanthropologist Lee Berger of the University of the Witwatersrand (Wits) in Johannesburg (see p. 1373), presents two remarkably complete and well-preserved partial skeletons, discovered 3 years ago in an ancient “deathtrap” in Malapa Cave in South Africa.

    Even though they are still excavating fossils and scraping calcified rock off the first two partial skeletons, Berger's team has begun to expose a creature that is partly ape, with a tiny brain, long arms, a chimp-size body, and a narrow birth canal. But it is also partly human, with short fingers, a long thumb that may be used for precision gripping, and a brain that has begun to reorganize more like a human's, Berger says. This particular mix of primitive and modern traits has prompted him to propose it as one of the last of the australopithecines—and perhaps even a member of the long-sought mystery species that gave rise to our genus, Homo, in Africa.

    Cradle of humankind.

    One group of Australopithecus, somewhere in Africa, gave rise to early Homo before 2 million years ago.


    The skeletons and their analyses convince few other researchers that Au. sediba was a direct ancestor of humans—but most scientists don't rule out that possibility. All agree that Au. sediba is a major find and an important relative because of its timing and completeness: So far, 40% to 60% of each skeleton has been excavated, and these hominins lived just after a significant gap in the fossil record 3 million to 2 million years ago. “It gives us a fresh new tsunami wave of evidence at this critical time when Australopithecus went extinct and Homo originated in Africa,” says paleoanthropologist Brian Richmond of George Washington University in Washington, D.C.

    Ape-men from the south

    South Africa is the site of the first australopithecine ever discovered, back in 1924, when anatomist Raymond Dart unearthed the skull of the Taung child and named it Australopithecus africanus, or “southern ape of Africa.” Over the next few decades, researchers found more specimens of Au. africanus in caves at Sterkfontein and Makapansgat, where the species has been roughly dated to about 3 million to 2 million years old. South Africa is also home to younger, so-called robust australopithecines, hominins with gorilla-like crests atop their heads that are not on the direct line of human ancestry. No new species of hominins had turned up lately in South Africa, although no one is sure of the affinities of a mysterious, extraordinarily complete, and still largely unpublished skeleton dubbed “Little Foot” from Sterkfontein (see p. 1374).

    For years, Au. africanus was considered a direct human ancestor, only to be knocked off that coveted position by the most famous australopithecine, the partial skeleton of Lucy, who comes from farther north in Hadar, Ethiopia. Most researchers have regarded Lucy's species, Au. afarensis, as the leading candidate for ancestor to our genus. Homo first shows its face, in the form of an upper jaw also from Hadar, about 2.3 million years ago. But what came between Lucy, dated to about 3.2 million years ago, and early Homo?

    Berger set out hoping to fill this gap in the fossil record. In 2008, he and his then 9-year-old son Matthew and their dog, Tau, found a collarbone at Malapa, just 15 kilometers northeast of Sterkfontein and Swartkrans (Science, 9 April 2010, pp. 154 and 195). Over the next month, Berger and colleagues found a partial skull and skeleton of a boy who was about 12 to 13 years old and a second partial skeleton of an older female. Berger thinks they fell into a hidden pit, perhaps while seeking water that percolated up from a series of underground caves. Since then, the roof of the cave collapsed, and the site is now an open pit in which Berger's team has found the remains of at least two other individuals, including an infant, although these other bones have not yet been analyzed. “These things are so extraordinarily complete that we're dealing with things we've never seen before,” Berger says.

    Au. sediba is dated to the murky period just after the rise of Homo and the demise of Au. africanus. Geochemist Robyn Pickering of the University of Melbourne in Australia measured the decay of isotopes of uranium into lead in a flowstone that capped the fossil-bearing layer at Malapa and got a precise date of 1.977 million years ago.

    Berger's team, questioning whether the 2.3-million-year-old Hadar jaw is really Homo, suggests that Au. sediba may in fact predate our genus. But other researchers have long accepted that jaw, which means that these skeletons of Au. sediba could not themselves have given rise to Homo, says paleoanthropologist Fred Spoor of University College London and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. However, Berger points out that even if Homo is older, the Malapa skeletons could represent a late surviving population of the species that, at another place and time, led to early Homo.

    Taking it from the top

    When Berger describes the hominin, he gives an enthusiastic blow-by-blow account of each body part, starting at the head, specifically the inner surface of the partial cranium, which retains the impression left by the boy's brain, or an endocast. Using the powerful x-ray microtomography scanner at the European Synchrotron Radiation Facility in Grenoble, France (Science, 7 December 2007, p. 1546), the team produced a close-up image of a tiny brain a bit bigger than a chimp's, only 420 cubic centimeters.

    The endocast has “the best resolution ever found on an African hominin,” Berger enthuses. Others agree. “The pictures of this thing are beyond belief,” says Ralph Holloway, a neuropaleontologist at Columbia University. “I've never seen anything so stunningly, graphically clear.”

    Head first.

    This virtual reconstruction of Au. sediba's skull shows the endocast of its brain surface (green) with an enlarged frontal gyrus (blue; areas reconstructed from a mirror image shown in yellow).


    Despite its small size, the brain is “striking,” Berger says, for the clarity of the convolutions on its surface, particularly in the frontal lobe. He says those areas are expanded and “foreshadow” the changes seen in the human brain, such as a larger right frontal lobe behind the forehead. Another bulge in the inferior frontal gyrus behind the left temple (see image) is unlike an ape's and may indicate that more neurons are interconnecting there, in a region in humans that has been linked to social behavior and language. “That definitely is a sign of reorganization in my mind,” says Holloway, who first proposed that the remodeling of the brain in our lineage wasn't driven by a general increase in size but by natural selection favoring key areas, such as those involved in language, social interactions, and tool use.

    Holloway and others warn, however, that it's premature to say Au. sediba's brain is more modern than those of other australopithecines, because Berger and Wits paleoanthropologist Kristian Carlson have compared the endocast with only three australopithecines from Sterkfontein. They should also have compared it directly with another Sterkfontein endocast that is convoluted, says paleoanthropologist Dean Falk of the School for Advanced Research in Santa Fe and Florida State University in Tallahassee. “To make a convincing case,” she says, “you need to look at all of the australopithecines in South Africa.”

    Becoming human?

    Many researchers think that Au. afarensis (left) eventually led to Homo, whose earliest fossil is this jaw from Hadar (right).


    As he continues to describe the fossil, Berger next shows his hand, literally: He cups the cast of the ancient hand inside his own to show how they are alike and different. Au. sediba's hand still flexes in a way similar to the hands of apes that climb trees. And it came with a long, primitive arm that suggests it often hoisted itself up into trees, Berger says. But he also points out that Au. sediba's fingers are relatively short, like his, and suggests that they worked with its long thumb to precisely grip objects such as stone tools. Such a precision grip is associated with Homo, although researchers have suspected that australopithecines might also have made early stone tools.

    But Au. sediba's anatomy didn't necessarily allow a precision grip, says paleoanthropologist William Jungers of Stony Brook University in New York state, who has seen the original fossils. He thinks it's “an australopithecine hand in essentially all relevant respects” and didn't manipulate objects in an advanced, humanlike way.

    The pelvis, reconstructed from fossils of both skeletons, is another puzzle. The angle of the pelvic blades is more vertical in the reconstruction, and they are S-shaped like a human's pelvis rather than that of Lucy, Berger says. But other traits, such as the diameter of the hip socket and the small size of the birth canal and sacral joint of the pubis, are like those in Australopithecus. This suggests that the redesign of the pelvis seen in Homo may have been driven by the need to walk upright more efficiently rather than to birth babies with bigger brains, which has been the leading view, the authors say.

    Again, other researchers want more comparative work before accepting that idea. Paleoanthropologist Carol Ward of the University of Missouri, Columbia, says they need to compare the new pelvis and bones with those of more australopithecines, to reevaluate which features are shared and which are truly unique to Homo. And there's no reason why the Homo pelvis couldn't be adapted to both improved walking and obstetrics, adds paleoanthropologist Scott Simpson of Case Western Reserve University in Cleveland, Ohio. “These authors present a false choice with either obstetrics or locomotor demands leading to the modern pelvis,” he says. Based on what's thought to be a H. erectus pelvis from Gona, Ethiopia, he thinks that Homo and Au. sediba adapted to walking upright in different ways and that early Homo was also balancing the competing demands of big-brained babies.

    Finally, the well-preserved and articulated bones of the partial foot, ankle, and lower leg add an odd footnote to the description of Au. sediba. As Aiello noted, the heel is very primitive: When Au. sediba walked upright, it had to put its weight on a small, angled surface rather than on a broad, flat heel bone, which must have affected the way it walked. The new heel “is particularly strange and quite unlike any other hominid,” says paleoanthropologist Bruce Latimer of Case Western. Yet it had more mobility in its ankle, so its knee would have been directly over the foot when it walked upright. Jungers agrees that the foot is a “marvelous mosaic” of primitive and modern traits. Along with the hand and shoulder, it suggests that different species of australopithecines, such as Au. afarensis and Au. sediba, evolved slightly different ways to walk upright, he says.

    Pelvic tilt.

    The pelvic blades of Au. africanus (left) flare more widely than those of the younger Au. sediba from South Africa (right; reconstructed parts are in gray or white).

    Arm vs. hand.

    Au. sediba's hand has some humanlike traits, but its arm is long and primitive.


    Sum of the parts

    Berger has put the new hominin in with the australopithecines rather than as an early member of Homo. But he points out that the new skeletons share several key traits with Homo that are not found in Lucy's species, citing the precision grip and reorganization of the brain. “We're not saying this is the direct ancestor, but if you start weighing this all, it will end up as the most probable ancestor,” he claims.

    For most researchers, exactly where Au. sediba should be placed in the family tree remains in doubt. Some think it is a late member of Au. africanus. “The skull and mandible … seem to represent no more than a young, female Au. africanus,” says paleoanthropologist Yoel Rak of Tel Aviv University in Ramat Aviv, Israel. If so, it would show that Au. africanus persisted longer than thought before it went extinct and would reveal that species' body proportions and variation over time.

    Others also see the similarities: “Au. sediba looks like a very reasonable descendant of Au. africanus,” Richmond says. But he thinks it is different enough to be named a new species.

    Berger looks at it another way: If Au. africanus did lead to Au. sediba, both were probably ancestral to Homo, he says—and Au. africanus would be restored to its old branch on the human family tree leading directly to humans. Or, he says, it's possible that Au. sediba is closely related to a common ancestor that it shared with early Homo.

    For now, though, no one's redrawing their family trees. Several researchers say that no matter whether Au. sediba is Au. africanus or something new, what it does show is that there is more than one way to “skin the bipedal cat,” as Latimer puts it. Au. sediba adapted to upright walking in a different way from that of other hominins alive in Africa nearly 2 million years ago, such as Au. robustus, H. habilis, and H. erectus. “Whatever you call these things, there seem to be a number of different species running around at the same time—a number of experiments in being hominin,” Ward says.

  5. Profile: Lee Berger

    Paleoanthropologist Now Rides High on a New Fossil Tide

    1. Michael Balter

    After a career marked by controversy, Lee Berger hopes new hominin fossils will salvage his mixed scientific reputation.

    In the lead.

    Lee Berger and his excavation team head for Malapa Cave.


    JOHANNESBURG, SOUTH AFRICA—Lee Berger is having the time of his life. For well over a year now, a steady stream of illustrious researchers, journalists, and dignitaries, including South Africa's president, Jacob Zuma, has flowed through Berger's paleoanthropology laboratory at the University of the Witwatersrand (Wits) here, eager to have a look at his spectacular hominin fossils. Berger never tires of opening the foam-lined cases that hold the precious 2-million-year-old remains of Australopithecus sediba and explaining with relish how he found them and what they might tell us about early human evolution.

    Some lucky visitors go away with souvenirs: an Au. sediba paperweight, a replica of its skull, and an autographed cover of the 9 April 2010 issue of Science in which the discovery was first announced.

    This week the media coverage is likely to kick into high gear as Science publishes five new papers by Berger and his colleagues, featuring more details and analysis of Au. sediba (see pp. 1370 and 1402).

    The fossils give Berger even more reason to do what he loves: share the story of human evolution with audiences from middle school children to politicians. Scientifically, Berger hopes the fossils will confirm his controversial views about the role of southern Africa in hominin evolution and the place of Au. sediba as a link to our own genus, Homo. “The fossils are stunning,” says anthropologist Leslie Aiello, president of the Wenner-Gren Foundation for Anthropological Research in New York City. “They are going to be food for thought in the field for a long time.”

    And yet Berger will have to work hard to convince the field that his team's interpretations are correct. His career has been dogged by controversy, and some of his peers find Berger, whose background includes a stint in TV news, heavy on style and light on substance. They say he has made exaggerated claims and serious errors, for example, in attempting to sideline the famed australopithecine “Lucy” as a human ancestor and claiming to have discovered skeletons of diminutive humans on the island of Palau that cast new light on fossils of H. floresiensis—dubbed the “hobbit”—from Indonesia.

    “Lee's scientific reputation is a very mixed bag,” says paleoanthropologist William Jungers of Stony Brook University in New York state. And Donald Johanson, co-discoverer of Lucy and a skilled popularizer of science himself, says Berger is “the grandstander of the field.” Johanson, of Arizona State University, Tempe, helped Berger start his career in the late 1980s but now thinks that Berger “often overstates the importance of what he has found.”

    Yet Johanson and other researchers say that Berger's strength is his passion for paleoanthropology. It was Berger's “boundless enthusiasm and energy” that led to the unearthing of Au. sediba, says Carol Ward, a paleoanthropologist at the University of Missouri, Columbia. “His perseverance has been second to none.”

    An American in South Africa

    Berger, 45, grew up mostly in Savannah, Georgia, the son of a businessman and a teacher. As a boy, Berger had little interest in school but loved science and the outdoors and took to leadership, becoming an Eagle Scout and president of the Georgia 4-H Club.

    After two unhappy years at Vanderbilt University in Nashville, Tennessee, he returned to Savannah, walked into a local TV station, and asked for a job. He worked his way up to news producer and cameraman and once saved a suicidal woman after hearing on police radio that she had jumped into a river; he drove downstream, dove into the river, and pulled her out. But after several months he returned to college at Georgia Southern University.

    Berger read Johanson's book Lucy and immediately decided he wanted to be a paleoanthropologist. When he learned that Johanson was coming to Savannah to give a talk, he called the famed researcher and invited him to stay at his parent's beach house. “He was my hero,” Berger says. Johanson came and, over breakfast, advised Berger to do his Ph.D. at Wits under Phillip Tobias, who co-discovered H. habilis.

    Berger followed Johanson's advice. At Wits, like so many who have encountered Berger, Tobias was impressed with the younger man's “singular drive” and “effervescent enthusiasm.” Says one researcher who knows them both, “Tobias adored Lee; he was like the son he never had.” When Tobias faced mandatory retirement, Berger, who had befriended many wealthy South Africans, raised three more years of salary for him. The university then hired Berger as Tobias's successor, choosing him over the more senior anatomist Ronald Clarke, who later found a treasure trove of fossils from Sterkfontein Cave (see sidebar, p. 1374). But soon Berger and Tobias had a major falling out. Tobias and Clarke claim that Berger tried to take credit for discovering the Sterkfontein fossils, a charge Berger denies and which university officials concluded was unfounded; university documents and interviews with the relevant parties support Berger's view.

    Science or showmanship?

    Until recently, Berger had in fact discovered relatively few hominins on his own. In 2008, dissatisfied with the smattering of teeth and fossil fragments his team had found over the past decade, he decided to scour the fossil-rich Cradle of Humankind north of Johannesburg for new hominin sites. He used Google Earth to spot cave systems, then drove up and down the dusty roads for days in his Land Rover. Malapa Cave is “right next to a dirt track that I had driven down a couple of hundred times in the last 20 years,” Berger says.

    One sunny day last spring, Berger led a convoy of visitors down that dirt track, past grazing zebra and wildebeest, to Malapa. Tall and burly with a boyish face, Berger led an entourage including former South African President Thabo Mbeki, Mbeki's standby medical team, two well-known anti-apartheid activists, and two local journalists who had spotted Mbeki and sneaked into the procession. On arrival at Malapa, which is actually a pit left by the collapse of a cave roof, Berger sat at the pit's edge and held forth about the fossils that have put South Africa back on the hominin map; some as-yet-unexcavated bones could be seen poking out of the earth.

    Berger captured the attention of his diverse audience that day. When it comes to presenting his ideas to his peers, however, his enthusiastic claims have drawn some skepticism—and sometimes worse, even when some of his basic findings have later been corroborated. Back in 1996, for example, Berger attracted attention with his claim that the South African species Au. africanus was a more likely ancestor to our own genus, Homo, than was Lucy's species, Au. afarensis, long considered directly on the human line. The hypothesis was in keeping with Berger's campaign to bring South Africa, long sidelined in human evolution studies in favor of East Africa, back to center stage.

    Berger and Henry McHenry, a respected paleoanthropologist at the University of California (UC), Davis, concluded that the body proportions of the more recent Au. africanus were closer to the earliest known Homo, H. habilis, than were those of Lucy's species, specifically in having relatively longer arms than legs. Berger himself went on to argue that on this basis, Lucy, queen of hominin skeletons, should be side-lined as a human ancestor and Au. africanus should take her place. “One might say we are kicking Lucy out of the family tree,” Berger was quoted saying (Science, 3 May 1996, p. 654). Berger now admits that such rhetoric was “a bit provocative” and due to “the errors of youth.” It brought Berger to the keen attention of UC Berkeley paleoanthropologist Tim White, who works in Ethiopia, where Lucy was found. Berger recounts in his 2000 popular book In the Footsteps of Eve that White—whom Berger calls the “Great White Shark”—and his colleagues descended upon Wits to challenge Berger's hypothesis, arguing among other things that early Homo fossils are too fragmentary for such comparisons.

    Berger and McHenry's basic findings on australopithecine body proportions were recently confirmed using more refined methodology, by a team led by anthropologist Brian Richmond of George Washington University in Washington, D.C. But few researchers other than Berger are ready to push Lucy off the human lineage because of this single piece of evidence.

    Then in 2008, Berger stumbled into another contentious paleoanthropological debate: the battle over the “hobbit,” the little people of Indonesia. Berger and colleagues announced that they had discovered skeletons of small-bodied modern humans on the Micronesian island of Palau and that a process of “island dwarfing” gave these modern skeletons some features that made them look evolutionarily primitive. Thus they questioned the traits used to assign the hobbit to a new species ( The paper made a contribution, says anthropologist John Hawks of the University of Wisconsin, Madison. “What does it mean to be small-bodied? It's an interesting point worth exploring.”

    Celebrity hit parade.

    Berger shows fossils to South African President Jacob Zuma (above left), and Jane Goodall, Al Gore, and Richard Leakey (top to bottom, right).


    But Berger, some say, was not content to let the science speak for itself. He collaborated with National Geographic on a documentary that claimed, for example, that Berger had made “a discovery that could change what we think we know about the evolution of mankind, … the remains of a people that are unlike anything discovered before.”

    Archaeologist Scott Fitzpatrick, a Palau expert at North Carolina State University in Raleigh, quickly pointed out that for years he and others had published on similar skeletons, which Fitzpatrick called “normal-sized” for the region. “Lee's Palau work was a regrettable farce in my opinion,” Jungers says, “and marks one of his lowest points.”

    But Berger and his team have stuck by their guns, insisting that their original observations on the Palau skeletons are correct. Berger has two grad students still working on the material. “I've been given the roughest ride in paleoanthropology,” he says. But, he claims, “the people attacking my science have turned out to be wrong.” Berger adds that the Palau episode made him even more determined to prove his credibility by finding fossils everyone could believe in, and spurred the search that led to Malapa.

    Jungers says that Au. sediba “is indeed salvaging Lee's reputation in several ways.” Among them is Berger's decision to permit other scientists full access to the new fossils, allowing them to examine casts at a recent paleoanthropology meeting (Science, 29 April, p. 534). Says Aiello: “I was very impressed with his performance at the meetings. He showed up with a suitcase with the skeletons in it. He was like a kid” in his excitement to share what he had found.

    Today, “Palau is water under the bridge,” says anthropologist Dean Falk of the School for Advanced Research in Santa Fe. “What is important is Au. sediba. He has his own fossils now, and that has not only changed the course of Berger's career, it is going to have a major impact on the field.”

  6. Paleoanthropology

    Little Foot, Big Mystery

    1. Michael Balter

    After nearly 15 years of excavation, the most complete hominin skeleton ever discovered, dubbed "Little Foot," is expected to be out of the cave in which it was discovered within the next 2 months.

    Paleo pride.

    Ron Clarke shows off the skull and arm bone of Little Foot, the most complete hominin skeleton known.


    STERKFONTEIN CAVES, SOUTH AFRICA—The descent into the Silberberg Grotto, down several flights of rickety metal stairs, can be treacherous because the cave is often dripping wet. The stairs end at the top of a slippery slope of hard dolomite, which must then be carefully negotiated to get to the treasure at the bottom: the remains of the most complete hominin skeleton ever discovered, dubbed “Little Foot.”

    The skeleton is virtually complete. It includes a beautifully preserved skull as well as arm, hand, and leg bones, the pelvis, plus many vertebrae and ribs. Part of it is still embedded in the cave's breccia. Now, after nearly 15 years of excavation, paleoanthropologist Ron Clarke of the University of the Witwatersrand (Wits) in Johannesburg and his co-workers say they expect to have the entire skeleton out of the cave within the next 2 months. They are studying the fossils in their lab near Sterkfontein Cave; Silberberg Grotto is just one of many hominin fossil–bearing chambers in that cave.

    Researchers agree that Little Foot may have much to tell about human evolution. “It's a wonderful fossil,” says William Jungers, a paleoanthropologist at Stony Brook University Medical Center in New York state, who has seen casts of the fossils. But just what it has to say is unclear: So far Clarke has published only very preliminary descriptions, and he and other researchers are locked in a sharp debate over the skeleton's age, with estimates as old as 3.3 million years and as young as 2.2 million years.

    Little Foot was so named for the small size of four hominin foot bones, which Clarke found earlier among previously excavated animal bones from Sterkfontein (Science, 28 July 1995, p. 521). By the late 1990s, Clarke and his co-workers had gone back to the grotto and realized that they had a nearly complete skeleton, with some bones still articulated, that had fallen into the cave. Since then, Clarke and Wits co-workers Nkwane Molefe and Stephen Motsumi have continued to chip away at the breccia, working under increasingly difficult and wet conditions.

    The scanty published descriptions suggest that Little Foot has a mix of primitive and more advanced traits. It has a primitive skull but a more modern hand, with a long and strong opposable thumb and relatively short fingers compared with those of modern apes. According to Clarke, the feet have both apelike and humanlike features, with the more primitive parts in the back of the foot. This makes the hind foot similar to that of other australopithecines including Australopithecus sediba, Jungers says, although he thinks the big toe may be more primitive than Clarke has indicated. Clarke concludes that Little Foot was fully bipedal but still a skilled tree climber. Jungers agrees: “It confirms that climbing and terrestrial bipedality are not mutually exclusive.”

    Clarke says Little Foot has similarities to and differences from both the 3.2-million-year-old Lucy from Ethiopia and the southern African species Au. africanus, which lived between about 3 million and 2 million years ago. Clarke thinks it might belong to a third species, but others suspect that it may be Au. africanus.

    Sterkfontein is only 15 kilometers from Malapa, where Clarke's Wits colleague and sometimes rival Lee Berger (see main text) found the 2-million-year-old Au. sediba. But Clarke and Berger won't be getting into a huddle over the two specimens anytime soon, as the two discoverers don't get along. Only a handful of other researchers have seen both skeletons, and they are reserving judgment until Little Foot's description is published. One of many possibilities, Jungers says, is that Little Foot was an ancestor of Au. sediba.

    Meanwhile, Clarke and three independent teams are getting divergent dating results. In 2000, Clarke's team, using known reversals of Earth's magnetic field, put the skeleton at 3.3 million years, making it a near contemporary of Lucy and the oldest hominin in South Africa. But since 2006, three other teams, using uranium-lead and paleomagnetic dating, have published dates ranging from 2.2 million to 2.6 million years, although they all regard the younger date to be more likely. That would make Little Foot about the age of the earliest known Homo and only a little older than Au. sediba. Clarke is now working with geologist Laurent Bruxelles of the University of Toulouse in France to produce their own new dates.

    So when will Little Foot, hidden so long in its dark and dank cave, be publicly unveiled? Clarke says that he expects to begin submitting papers on the hominin's anatomy by the end of 2012. Paleoanthropologists will be watching for such “detailed quantitative analyses,” Jungers says. “The ball is in Ron's court.”

  7. Superheavy Elements

    Which Way to the Island?

    1. Daniel Clery

    As teams vie to create the next new addition to the periodic table, the best path forward for superheavy-element research remains unclear.

    Land ho!

    Known nuclei (filled-in squares) are nearing the island of stability (dark patch, upper right).


    Last month at the Helmholtz Centre for Heavy Ion Research (GSI) in Darmstadt, Germany, a team of physicists and chemists from across the globe began firing an intense beam of titanium ions at a thin foil made of californium. They will continue to bombard it, day and night, until October. Their aim is to make a handful of atoms—or even just one—of a type that has never before existed on Earth: element 120. “It's a long run, an exciting run,” says team leader Christoph Düllmann of GSI and the University of Mainz in Germany. “There's no guarantee that we'll find it, but we have a good chance.”

    Science knew of only 92 naturally occurring elements until physicists examined what was produced in the first nuclear reactors and explosions and found new ones: neptunium, plutonium, americium, and others. Later, researchers began making them with particle accelerators. A few centers around the world got the process down to a fine art, and every few years it seemed new elements were being discovered and named. The heaviest to date, element 118, was first made in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia.

    But creating new elements is not just nuclear stamp collecting. How long-lived, or stable, each new element is helps to confirm or refute theories of how nuclei work. Their chemistry teaches us about the structure of the periodic table of elements. And there is a more tantalizing goal: the island of stability.

    Most superheavy nuclei are not blessed with a long life. They either split apart in a nuclear fission after a few microseconds or spit out a few alpha particles first and then fission. But theories of nuclear structure predict that certain key numbers of protons and neutrons in a nucleus, known as magic numbers, make it more stable and hence longer-lived than would normally be the case. The nuclei of calcium, nickel, tin, and lead are all exceptionally stable, and theorists believe this is because they have magic numbers of protons, neutrons, or both. Nuclear physicists predict that more magic numbers exist for nuclei larger than the 118 known elements. In theory, superheavy nuclei with these magic numbers of both protons and neutrons—or even just close to them—might last for hours, days, or as some believe, millions of years.

    Superheavy-element researchers call this area of the chart of nuclides, around the confluence of proton and neutron magic numbers, the island of stability. The half-lives of some of the heaviest elements made so far do show signs of increased stability, suggesting that those nuclei are on the shores of the island. Moving farther inland is an enticing prospect because the atoms we may find there could be exotic creatures indeed. For atoms this size, the regular procession of properties predicted by the periodic table breaks down, and chemists don't know what they will find.

    But for the time being, the summit of the island's peak is out of reach because physicists haven't devised a way of making nuclei with enough neutrons. The next neutron magic number is 184, but the most neutron-rich nucleus made so far—element 116—has 177 neutrons, still seven short of that goal. There is some dispute about what the next proton magic number is. Some theorists predict 114, others 120 or 126. “It's still an open question. We have to find this out by experiment,” says superheavy element veteran Sigurd Hofmann of GSI. With luck, the current GSI experiment will tick one of those boxes.

    Beyond that, it's anyone's guess. The current favorite synthesis technique, known as hot fusion—pioneered by the team at JINR and used to make elements 113 to 118—is running out of steam. Few think it will be able to make anything beyond element 120, if that. Physicists could extend its life by building a new dedicated accelerator to produce ultraintense particle beams, but in the current financial climate, no one is betting on it. Other suggested approaches would require new types of detectors that so far exist only on the drawing board. So if the GSI team does succeed in creating element 120, it may be a while before researchers get the pleasure of naming another.

    Magic bullets

    Three groups have long dominated the creation of new elements beyond uranium. The Berkeley Radiation Laboratory (now Lawrence Berkeley National Laboratory, or LBNL) pioneered the field, discovering everything from neptunium (element 93) to lawrencium (103). But advances in technology gave JINR an advantage in the 1960s and '70s and enabled researchers there to make elements 104 to 106 (rutherfordium, dubnium, and seaborgium). GSI got the upper hand in the 1980s and '90s with a string of discoveries from bohrium (107) to copernicium (112).

    To create new elements, researchers accelerate an intense beam of light ions and bombard a thin foil target made of heavy atoms. The target is made into a disc that spins so that no part of it stays in the beam long enough to melt. Out of the back of the foil target spew beam ions that have gone straight through, target atoms knocked out of the foil, and other debris. Very occasionally, a beam ion hits a target nucleus head on to form a compound nucleus that recoils out of the foil. Normally, such a large, energetic new nucleus would immediately split apart. But thanks to magic numbers, an added force holds some nuclei together so they don't fission immediately. Instead, they spit out a few neutrons to shed energy and then pause briefly before beginning to decay by emitting alpha particles (helium nuclei).

    Quick shooter.

    GSI's UNILAC accelerator fired 7 × 1018 chromium ions at a curium target earlier this year, but researchers didn't find any element 120.


    To spot those unusually durable but still fleeting nuclei, researchers have to separate them out from all the other stuff spewing out of the target. They do it by passing the beam of particles through a strong magnetic field that deflects particles by different amounts, depending on their mass and their charge. By varying the field, researchers can steer the desired compound nuclei toward a detector, leaving other particles to hit the walls of the recoil chamber. The latest separators can extract as much as 60% of the compound nuclei produced.

    The detector is a block of silicon loaded with electronics that senses a nucleus striking the material, logs its position, and then measures its subsequent alpha decays. The sequence of decays, their energies and timings, is the signature researchers need to identify the superheavy element.

    In its heyday in the 1980s and '90s, GSI sought new elements through a technique called cold fusion, which used a relatively low-energy beam designed to minimize the energy of the compound nuclei so they were less likely to fly apart. But in 1998, the JINR team claimed the discovery of element 114 using hot fusion. This technique employs a higher energy beam, which is more likely to penetrate the target nucleus. To counteract the instability of a high-energy compound nucleus, the team used a beam of calcium-48—an ion with magic numbers of both protons and neutrons that give it extra stability. “Calcium-48 is pretty special,” says Ken Gregorich of LBNL. “It's doubly magic, extremely neutron-rich. There's nothing like it.”

    By firing calcium-48 at increasingly heavy target elements, the JINR team and various U.S.-based collaborators created elements 113 to 118. (A team at the RIKEN laboratory in Wako, Japan, also claims the discovery of element 113 using a cold fusion reaction. The claims are still being investigated.) With element 118, the era of calcium-48 came to an end. The target in that synthesis, californium, was the heaviest one available. Among heavier elements, only one—einsteinium—has been produced in sufficient amounts to be seen with the naked eye, and it has a worldwide production of about a milligram per year.

    Forced to abandon their golden bullet, researchers have started trying out heavier projectiles. Several attempts to create element 120 have been or are being made. (Researchers are avoiding element 119 for the time being because even-numbered elements have a slight stability advantage.) JINR is trying with a californium target and titanium projectile—so far without success. Earlier this year, the GSI team bombarded a curium film with a beam of chromium ions for 33 days but did not detect element 120.

    On target.

    Christoph Düllmann's team is now aiming for element 120.


    Now a different team at GSI, led by Düllmann, has entered the race with a newly built separator and high hopes for success. The effort started almost a decade ago, when nuclear chemists at GSI and elsewhere were itching to study the properties of atoms heavier than element 108, hassium. The detectors used in most superheavy experiments, however, were relatively simple event counters that got overwhelmed by the stream of debris coming from the target, leading to a noisy environment. “There was a clear need to get rid of the background,” Düllmann. The chemists purloined some magnets from a retired experiment and in 2005 built a new, much improved separator designed to feed a nice clean beam into a particle detector or other chemistry experiment.

    Using GSI's UNILAC accelerator and the new Transactinide Separator and Chemistry Apparatus (TASCA), the team created 13 atoms of element 114 in 2009, helping to confirm JINR's discovery. “This established TASCA as a forefront device,” Düllmann says. Now the team has been given a large chunk of beam time to have a stab at element 120.

    Like JINR, the GSI group fires a titanium beam at a californium target. The readiness of two nuclei to react with each other in a collision is known as the reaction cross section; the smaller the cross section, the less likely the reaction. The cross sections for the few elements running up to 118 were fairly constant. But now, LBNL's Gregorich says, experimenters have entered terra incognita. Theorists agree that the cross section will get smaller, but their predictions of how much it will shrink vary by orders of magnitude. “With element 120 we're shooting in the dark,” Gregorich says. “If the cross section is a factor of 5 smaller, it'll work. If it's a factor of 20 smaller, it won't.”

    If the cross section turns out to be on the small side, then it becomes a question of how long lab directors allow these searches to dominate the use of their accelerators. It could take many months of beam time just to get one or two atoms of a new superheavy element. Here the team at RIKEN has an advantage because it has a dedicated accelerator, RILAC, and so can do long beam runs. “They could really make a play to discover new elements,” LBNL's Rod Clark says.

    On the horizon are the prospects of new accelerators with much more intense (more particles per second) beams that could speed up the superheavy search. One such is SPIRAL2, currently under construction at the GANIL heavy-ion research lab in Caen, France, which will begin operation in 2012 or 2013. Researchers at LBNL have also considered pitching for a new ultra-high-intensity linear accelerator at a cost of about $100 million. “It's feasible, but it's a matter of getting the worldwide superheavy element community working together,” Clark says.

    Wanted: Neutrons

    But adding protons to make new elements is not the only frontier. Researchers also hope to move toward the island of stability by adding more neutrons to elements already discovered. Driving the search is a quantum-mechanical theory of how atomic nuclei are put together. The classical “liquid-drop model” pictures a nucleus as a random jumble of protons and neutrons held together by “binding energy” much like the surface tension that holds together a drop of water. This model predicts that elements greater than 100 ought to be too unwieldy to exist, and it cannot explain all the differences in stability that researchers see among nuclei.

    To overcome its flaws, theorists in the late 1940s superimposed a quantum model in which protons and neutrons are arranged in “shells,” analogous to the atomic shells electrons occupy around the nucleus. And just as a full electron shell leads to a chemically stable atom, such as a noble gas, so a full proton or neutron shell—a magic number of protons or neutrons—gives a nucleus extra stability. But the nuclear shell model is a many-body problem that is impossible to solve conclusively, so different theorists use different approximations with a variety of results. Hence there is some disagreement over where the island of stability is, or if it exists at all.

    Researchers have seen signs of “shell effects” among superheavy elements. There are proposed proton magic numbers at 108 and 114, and some nuclei of those elements survive for seconds before decaying—thousands of times longer than usual. Significantly, the four known isotopes of element 114 become more long-lived with each added neutron, suggesting that there is a neutron magic number in the vicinity. Theorists currently think the summit of the island of stability will be at or near 114 protons and 184 neutrons.

    Looking ahead.

    GSI's Sigurd Hofmann says the future direction will depend on the results of current searches for element 120.

    Cleaner beam.

    TASCA's new particle separator aims for high efficiency and low noise.


    But moving closer to 184 neutrons is proving a tough nut to crack. The chart of nuclides tends to bend over toward more neutron-rich nuclei as the nuclei get bigger. “We may not get [to the island]. No combination of target and projectile has enough neutrons,” says Yuri Oganessian, head of the JINR team. New facilities currently in the works, including Michigan State University's Facility for Rare Isotope Beams and GSI's Facility for Antiproton and Ion Research, will soon be churning out beams of short-lived radioactive ions, including neutron-rich ones that could be used as projectiles to make neutron-rich superheavies. But researchers in the field say the beams will not be intense enough to be useful to them.

    Another possibility is an entirely different sort of reaction that involves colliding large nuclei, such as uranium with uranium or curium with curium, at relatively low energy. The nuclei would not fuse but would form a short-lived association that, occasionally, would allow protons and neutrons to move from one nucleus to the other before they break apart. Researchers at GSI studied such reactions several decades ago, Düllmann says, “but this avenue was not followed because finding new elements was more exciting.” There's been a revival of interest, he says, because “this is probably the best route to more neutron-rich nuclei up to element 108.” New detectors would be needed to detect the disintegrating nucleus pairs, which could fly off in any direction. GSI researchers have simulated such a detector, dubbed the Inelastic Reaction Isotope Separator.

    Nuclear theory veteran Walter Greiner of the University of Frankfurt in Germany advocates a direct approach to producing neutron-rich superheavy elements in bulk: taking a sample of a superheavy element and bombarding it with neutrons in the hope that some will lodge in its nucleus. Today's nuclear reactors aren't up to the job, Greiner says, as they produce at most 1015 neutrons per square centimeter per second (cm−2s−1). What is needed is a purpose-built pulsed reactor producing 1021 or 1022 neutrons cm−2s−1. “Building such a pulsed reactor would be like developing a new accelerator at CERN,” he says.

    Even better, Greiner says, would be to set off two or three nuclear explosions near a suitably protected target sample deep underground. Such an experiment, he calculates, would produce milligram quantities of priceless neutron-rich nuclei. “The Russians are not completely against this,” Greiner says, although it is hard to list all the practical and political hurdles to such an approach, not least the Comprehensive Nuclear-Test-Ban Treaty. “Our Greens [German politicians] would crucify me,” he jokes. “But for scientific purposes, maybe?”