News this Week

Science  02 Aug 2013:
Vol. 341, Issue 6145, pp. 440

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  1. Around the World

    1 - Brussels
    E.C. Lays Groundwork for Defense Research
    2 - Washington, D.C.
    U.S. Alters R&D Accounting
    3 - Batavia, Illinois
    Giant Magnet Arrives at Fermilab
    4 - Pacific Northwest
    Killing One Species to Save Another
    5 - Tokyo
    More Hypertension Drug Probes



    Europe proposes funding to study drones and other technologies.


    E.C. Lays Groundwork for Defense Research

    In an attempt to bolster Europe's ability to counter global security threats, the European Commission has proposed that the European Union consider funding military research. Observers say that the proposal could encourage cooperation in an area that has largely remained the turf of individual countries.

    The commission is not suggesting using the region's primary vehicle for cooperative research, Horizon 2020. That program will keep an "exclusive focus on civil applications," the proposal says. But the commission wants to see if some technologies funded by Horizon 2020 could also be used in defense applications.

    Commission President José Manuel Barroso presented the plans on 24 July, along with two European commissioners. "Twenty years ago it wouldn't have been natural for the commission to talk about defense. [But] times have changed," Barroso told reporters. Spending on military research in E.U. member states dropped by 14% from 2005 to 2010, and the unspoken fear is that Europe may be falling behind in developing new technologies such as drones and systems for detecting new biological, chemical, and nuclear weapons. The proposal will be discussed at the European Council meeting in December.

    Washington, D.C.

    U.S. Alters R&D Accounting

    The way the United States accounts for the value of research and development spending is getting a major makeover. On 31 July, the U.S. Bureau of Economic Analysis began factoring R&D expenditures by business and government—estimated at some $400 billion last year—into its regular tally of the nation's gross domestic product (GDP), a key measure of economic health. In the past, GDP bookkeepers essentially counted R&D spending as an expense. Now, it is treated as an investment. Government analysts predict that the change will slightly boost annual GDP. If R&D had been treated as an investment between 2002 and 2007, for instance, average annual U.S. GDP growth would have been 0.12 points higher. Other studies estimate that, in 2007, R&D spending accounted for 3% of the roughly $13 trillion U.S. GDP.

    Batavia, Illinois

    Magnetic attraction.

    The Muon g-2 ring during its travel to Fermilab.


    Giant Magnet Arrives at Fermilab

    On 26 July, a 15-meter-wide superconducting magnet rolled through the gates of Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois—the last step of a nail-biting 5000-kilometer journey that moved the delicate ring-shaped magnet from Brookhaven National Laboratory in Upton, New York, to its new home on the prairie.

    The ring is part of the "Muon g-2" experiment, intended to precisely measure the magnetic moment of an elementary particle called the muon in hopes of detecting long-sought-after hints of new physics. An earlier experiment at Brookhaven produced a result that didn't agree with the standard model; now, the Fermilab team hopes to conclusively confirm or refute that result by repeating the experiment with an improved muon beam.

    Fermilab scientists plan to start testing the magnet within the next few weeks, but won't know for sure whether the ring survived its journey unscathed until 1 year from now, when they try to cool its coils back down to superconducting temperatures. The team hopes to start taking data in 2016.

    Pacific Northwest

    Northern spotted owl

    Barred owl


    Killing One Species to Save Another

    The U.S. Fish and Wildlife Service (USFWS) announced last week that it plans to dispatch hunters beginning this fall to shoot more than 3600 barred owls in California, Oregon, and Washington over the next 4 years. The cull is an attempt to prevent further population declines of the northern spotted owl, which is in danger of extinction.

    An emblem of the Endangered Species Act, northern spotted owls have seen their numbers sharply decline since 1990, when federal officials listed the birds as threatened. The listing halted logging in much of the Pacific Northwest's old growth forests, the spotted owls' preferred habitat. But barred owls—which are larger, more aggressive, and less picky about what they eat—also inhabit these forests. Northern spotted owl numbers are declining by 2.9% each year, and "we can't ignore the mounting evidence that competition from barred owls is a major factor," says USFWS Director Daniel Ashe.

    Once the barred owl hunt is complete, wildlife officials will monitor spotted owl populations and see whether they fare better than in regions taking no action against the barred owls. The hunting plan is expected to be finalized later this month.


    More Hypertension Drug Probes

    Another investigation has cast doubts on claims for a leading hypertension drug. In April 2007, results from the Jikei Heart Study, published in The Lancet, claimed that patients taking valsartan were at a lower risk of heart failure and stroke than those on alternatives. But on 30 July, an investigation at Tokyo's Jikei University School of Medicine concluded that the Lancet paper "is fundamentally flawed" due to data manipulation and conflicts of interest.

    Four other universities are conducting investigations; last month, investigators at Kyoto Prefectural University of Medicine found data manipulation in a valsartan paper based on a clinical trial at that school as well (Science, 19 July, p. 223). Valsartan is sold in Japan by Novartis Pharma, the Japanese arm of the Swiss pharmaceutical giant.

  2. Newsmakers

    Head of European Food Authority Resigns



    French food safety expert Catherine Geslain-Lanéelle unexpectedly stepped down as head of the European Food Safety Authority (EFSA) on 24 July to take up a new high-level job at the French Ministry of Agriculture, Food and Forestry. Her move came in the middle of her second term, slated to end in 2016. EFSA did not offer an explanation for Geslain-Lanéelle's departure, but a source close to the agency says her new post was too good to pass up.

    "She was deft at networking and her political judgment was good," writes Joe Perry, chair of the agency's panel on genetically modified organisms, in an e-mail. "I hope EFSA can get someone of her calibre as a replacement."

    EFSA was established in 2002, charged with providing independent scientific advice on the safety of food and feed in the European Union. Veterinary expert Bernhard Url, in charge of risk assessment at EFSA, will lead the organization until an interim executive director is appointed in October. EFSA's management board will choose a new executive director from a shortlist to be drawn up by the European Commission.

    'Hobbit' Discoverer Dies



    Archaeologist Michael Morwood, co-discoverer of Homo floresiensis, the "hobbit" of Indonesia, died on 23 July after battling cancer. He was 62. In 2003, Morwood, then of the University of New England (UNE) in Armidale, Australia, and colleagues announced finding the skeleton of a woman barely a meter tall and with a tiny brain, who lived 18,000 years ago on the Indonesian island of Flores. The find was controversial: Some scientists suggested that the skeleton was a diseased H. sapiens, not a new species (Science, 10 August 2007, p. 740). Most claims for specific diseases that might have afflicted the hobbit have since been discredited, although researchers have yet to uncover H. floresiensis bones anywhere other than Liang Bua Cave on Flores.

    Morwood got his start studying Australian rock art. He returned to such analyses in recent years—while continuing to hunt for hobbit bones—at the University of Wollongong in Australia.

    Morwood "embodied what archaeology in a university department should be about—both creating and passing on knowledge about the past," says archaeologist and colleague Iain Davidson of UNE. "His ability to work with [indigenous peoples] and with Indonesian scholars is testament to his humanity."

    They Said It

    " Changing the language we use to diagnose various lesions is essential to give patients confidence that they don't have to aggressively treat every finding in a scan."

    —Oncology surgeon Laura J. Esserman to The New York Times, on a report she co-authored in The Journal of the American Medical Association that recommends restricting "cancer" to lesions likely to be lethal if left untreated.

  3. Random Sample

    The Architecture of Antarctica


    A research laboratory fit for the coldest, windiest, driest place on Earth must be sturdy, self-sufficient, and state-of-the-art—and represent its home country with pride.

    Inspired by the construction 3 years ago of the United Kingdom's fully relocatable and caterpillarlike Halley VI (pictured) on the Brunt Ice Shelf floating on the Weddell Sea, the British Council commissioned Ice Lab, a new exhibit of modern Antarctic labs that opened on 26 July at The Lighthouse in Glasgow ( The exhibit includes images of Belgium's zero-emission Princess Elisabeth station, India's shipping-container conglomerate Bharati Research Station, South Korea's Death Star–like Jang Bogo, and a design by a Danish architect for a future station made entirely from ice.

    "Each station is really interesting in its own right," says Vicky Richardson, director of architecture, design, and fashion at the council—and their construction doesn't just reflect accelerating international interest in Antarctic research, she adds. "They're almost a statement of national pride," competing with one another in stylishness, size, and technical complexity.

    NASA Investigates Space Vikings


    For Ved Chirayath, an aeronautics and astronautics graduate student at Stanford University in California, an online photo project that involved NASA researchers dressed as Vikings was just a creative way to promote space science. Chirayath, an amateur photographer who also works at NASA's Ames Research Center (ARC) on compact research satellites known as "CubeSats," never suspected that his fanciful image would put him in the crosshairs of a government waste investigation.

    CubeSats, he says, reminded him of Viking explorers who "travelled farther and saw more in much smaller ships than had been used before their time." That connection inspired his Space Vikings photos, snapped with the participation of a few costumed NASA researchers as well as a living history group called the Vikings of Bjornstad.

    But on 10 July, Senator Charles Grassley (R–IA) wrote to NASA chief Charles Bolden, asking him to investigate whether Chirayath's photos involved the possible misuse of ARC funds and staff time. Grassley asked Bolden to help him "better understand the participation of NASA employees and resources in this for-profit photography exhibit."

    Chirayath says that his effort was strictly not-for-profit and didn't involve ARC funds—and NASA News Chief Allard Beutel says the agency concluded that no taxpayer funds were used for Space Vikings. "The employees were on their time, not on work time."

    The flap left Chirayath perplexed. "NASA can't afford to promote their missions in this way and this is partly why I started this project," he says. And that's ironic, he adds, because "more was probably spent in taxpayer employee man-hours investigating me, my exhibition, and those involved than it might have cost" to produce the photos professionally.

  4. Venturing Back Into Colombia

    1. Antonio Regalado*

    In rural areas where guerrillas and drug traffickers have long been in control, researchers are now on the scene—but so are cattle ranchers, miners, and palm oil planters.

    Botanical hunt.

    Colombian and U.S. field researchers trek into the Andean forests of Las Orquídeas National Park.


    BOGOTÁ—Douglas Daly, a U.S. expert on Amazonian plants, vividly recalls the collecting trip that he took to Colombia in 1987. Jostling along a rutted track in their Jeep, he and three colleagues ran into a group of nervous men with AK-47s. The guerrillas demanded to know who the intruders were and why they had so much gear. Daly sweated through the grilling, pretending to be Brazilian. He got by but says, "It was a wake-up call. We got out of there and didn't go back." Not for 20 years.

    Now Daly, the curator of Amazonian botany at the New York Botanical Garden in the Bronx, is going back—again and again. In April, he made his third scientific expedition to Colombia since 2010, collecting 500 plants in 2 weeks, "four or five of which are new to science," Daly says. "That is probably the best haul I've had in that short a time."

    Colombia is a country of huge biodiversity. It ranks first in the world in number of flowering plants, second in birds, and sixth in mammals, according to the Food and Agriculture Organization of the United Nations. The twin Andes mountain ranges running north to south carve spectacular transitions between the jungle and the two ocean coasts where species flourish and evolve. Yet the fauna and flora are not as well described as those in neighboring countries. A decades-long civil conflict, pitting guerrillas in remote bases against the government, turned much of the countryside into a no-go zone for science.

    But over the last decade Colombia's government has pursued a successful security campaign to take back roads and territory; it is now engaged in peace negotiations with the guerrillas. Conflict has been winding down, drawing biologists back to the field. They've made a surge of discoveries, describing new species of frogs, birds, even monkeys. "It's true," says Brigitte Baptiste Ballera, director of the Alexander von Humboldt Biological Resources Research Institute, in Bogotá. "The map for science has changed."

    But scientists aren't the only ones racing back. Gold miners, oil companies, and cattle ranchers—also excluded by the conflict—are also taking advantage of the spread of peace. Along with opportunities for study, researchers see new and unprecedented risks to biodiversity.

    Daly says that he experienced a swirl of contradictory emotions in April during a visit to the department of Guaviare, where he collected leaves, branches, and green fruit from an as-yet unnamed tree. "To go to a habitat and find [that] the dominant tree has no name—well, that is pretty intense," Daly says. Yet on a flight over the country, he says, mostly what he saw from the window was the spread of cattle ranches and African oil palm plantations.

    It comes with the job

    Changing environment.

    A 2012 study reported on a decade's changes in forest cover in and around Colombia.


    In the late 1980s, as rebels gained ground, foreign researchers began to decamp from Colombia. But many local scientists found ways to continue their fieldwork. Marxist rebels in many cases regarded professors as sympathetic. With the right contacts, some scientists spent months in the jungle, although the work had its hazards. "I knew [the guerrillas] pretty well," says Andres Etter, a forest expert at the Javeriana University in Bogotá. "But starting around 2001 we became targets for kidnapping, too."

    John Lynch, an American frog specialist at the National University of Colombia in Bogotá, was kidnapped twice, each time released after a day or two. Once he was held in a wooden cage. "It was the cost of doing fieldwork," he says. By the late 1990s, right-wing paramilitary groups emerged as a new threat, along with well-organized cocaine producers. Tens of thousands of people were killed, including 10 employees of Colombia's national park service while on duty. The respect for professors ended, says Baptiste, who was threatened by a paramilitary group. "So the universities stopped going in and stopped doing fieldwork."

    Field stations shut down, and many top students left for Mexico or Venezuela. "Science kept going, but at a very slow, painful pace," says Paola Pedraza, assistant curator at the New York Botanical Garden, and a Colombian. Without adequate funding or expertise, Colombia lagged, she says, especially in DNA-based phylogenetics and bioprospecting. Colombia became a blank spot on modern maps of species. At the Missouri Botanical Garden, a large U.S. herbarium in St. Louis, the number of new plants sent in from Colombia between 2000 and 2009 was 85% lower than in the 1980s, according to Pedraza, who analyzed submissions.

    The information gaps made it more difficult to evaluate risks from climate change and identify biodiversity hot spots that need management. This work is critical for Colombia because its high-altitude, cool-weather species will have no escape as temperature rises. They can only migrate upwards, until they run out of mountain. Stuart Pimm, a conservationist at Duke University, in Durham, North Carolina, warns that Colombia could be hit with a record rate of extinctions.

    Return to the field

    Armed groups still hold sway in many parts of Colombia, including some of the most biologically interesting areas. The lowlands of Cauca on the Pacific Ocean, for example, are risky. With 13 meters of rainfall a year, "it's one of the wettest places on earth," Lynch says. "The number of frogs is astonishing. … But it's pure narcotraffickers, and you'd be a fool to go. So it's one of the blank spots on my map."

    Biologists are surging back elsewhere. The payoff in the Sierra Nevada de Santa Marta on the Caribbean coast, for example, has been swift. "We have gone from just dreaming of getting into these areas to having relatively good samples," says J. Van Remsen, an ornithologist at Louisiana State University in Baton Rouge who maintains the South American checklist of bird species. Among Remsen's finds, made near Bogotá, was Grallaria kaestneri, a bird last spotted in the 1990s when the initial, or type, specimen was collected. This time, Remsen says, "we also got recordings of vocalizations and a DNA sample."

    Pedraza was among those who decided the time was right to return in 2010, when she loaded up mules for an expedition into Las Orquídeas National Park, all but unvisited by international researchers since the 1990s. Her four expeditions since then have been bonanzas, she says, each yielding "four or five new species" in the group of tropical blueberry she specializes in. "This is what you get for going for a few days."

    Others echo Pedraza's excitement. "We are discovering lots of new [bird] species" many of them not even rare, says Andrés Cuervo, an ornithologist who works with Remsen at Louisiana State University. With four Colombian colleagues last year, he described a new type of wren in the northwest of the country. Like Pedraza, he complains of red tape, including "an unbelievable bureaucracy" that is especially meticulous about permits for collecting specimens and sampling DNA, although two new decrees issued in June are expected to cut through the paperwork. As a result, he says, even though Colombia is a bird paradise, it is lagging behind its neighbors Ecuador and Venezuela in cataloging its species.

    Race with development

    Biologists realize that the civil conflict brought a fortuitous—and likely temporary—benefit. Even though there is growing deforestation in Colombia, the war kept many areas isolated and also led to a wide regrowth of secondary forests on land that farmers had abandoned in their retreat to the cities. This provided moisture for frogs and habitat for migratory birds. "If you leave the highway you can see the fields growing back," in many regions, says Etter, the forest expert.

    With researchers at the University of Puerto Rico, Río Piedras, Ana Sánchez-Cuervo and T. Mitchell Aide, Etter published a satellite study last year reporting that between 2001 and 2010, while its neighbors lost forest, Colombia actually gained 17,000 square kilometers of woody vegetation. Although Etter thinks the evidence points toward the conclusion that war helped nature, he warns that this isn't certain. "We don't know what this country would have been like without the violence," he says. Etter says that the finding has been controversial, because people don't want to believe that any good came of the conflict.

    As fighting ebbs, road builders, miners, and ranchers are racing into many of the same regions that biologists are exploring. For instance, Pedraza says that on her most recent trip, even in the most inaccessible corners, her team came across many families mining gold, part of a wider illegal mining boom in Antioquia, where the presence of more than 15,000 artisanal mines have given its towns the highest level of mercury pollution in the world.

    The national government is encouraging development with tax breaks for palm oil plantations and biofuels. Foreign investments in Colombia's petroleum sector leapt 20-fold in 2011 over the level a decade ago, to more than $9 billion. Mining companies looking for coal and gold account for $4 billion more invested per year.

    Colombia has a large network of national parks and strong, if sporadically enforced, environmental laws, conservationists say. "It's a world leader on paper," says Andrew Jarvis, head of policy analysis at the International Center for Tropical Agriculture in Cali, Colombia. But, he adds, "if you look at the budget of the national parks system—it's quite pathetic." Colombia's parks agency has $30 million to protect 57 parks covering 127,000 square kilometers.

    Conservationists have been trying to inject biodiversity into the debate over Colombia's priorities. In March 2012, for instance, Conservation International awarded President Juan Manuel Santos its "Global Conservation Hero" award. Critics jeered that it was undeserved, as they claim Santos's record isn't very strong. But the conservation group said that the president was sending the right "signals." A year earlier, the government responded to severe floods by citing climate change and soil erosion as national priorities. Baptiste, the Humboldt director, says that makes her optimistic. She says, "People are now talking about biodiversity as part of national security."

    • * Antonio Regalado is a writer in Boston.

  5. Discovery of a New Titi Monkey

    1. Antonio Regalado

    A young Colombian researcher made the find of a lifetime when he discovered the red-bearded titi monkey.

    In the field.

    Javier García in a stand of trees that is home to the red-bearded titi monkey (below), a new and endangered species he described in 2010.


    FLORENCIA, COLOMBIA—Javier García was an undergraduate when he made the find of a lifetime in 2008—a new primate now listed as Callicebus caquetensis, the red-bearded titi monkey. Biologists had heard that such a creature might live in this remote hot spot, García's home province of Caquetá. But they were reluctant to venture into a place where rebels and paramilitaries battled over territory and U.S.-financed aircraft sprayed herbicide on coca plants (see main story, p. 450).

    Discovering a new species at age 22 launched García as a conservationist. He is working on a master's degree in primatology at the National University of Colombia in Bogotá. Meanwhile, he has been tramping across the ranch-flattened landscape of Caquetá to complete a census of the cat-sized monkey. But now, he says, "it's very painful" to realize that the animal is in trouble as its habitat shrinks.

    Biologist Martin Moynihan was the first to suspect the presence of an unidentified species in 1976, when he saw a titi monkey lacking the typical white face stripe. Moynihan hypothesized that it was a new species or subspecies associated with swampy, humid terrain. Thomas Defler, Colombia's leading primatologist and García's academic adviser, wanted to follow up but says that "it was impossible" to venture into Caquetá. Then García arrived at the university. "Javier was willing to go and enjoyed the reputation of his father," a well-regarded local veterinarian, Defler says.

    García took Science on a drive along 40 kilometers of highway and dirt roads, and finally a short trek by foot to visit a group of monkeys. Before setting out, García stocked up on T-shirts emblazoned with the monkey's face, miniature field guides to hand out as gifts, and a camera preloaded with pictures of animals. All of these are safety precautions. "When you start talking about monkeys in a zone with problems of armed conflict, people think you are making it up," García says.

    This part of Caquetá, once Amazonian jungle, has been almost completely deforested. García found that small groups of the red-bearded titi survive in forest fragments with as few as 40 to 50 trees. Using satellite images, he and Defler estimated that in some municipalities of the region less than 2% of the original jungle cover remains. The monkey is now listed as critically endangered, one of 14 monkeys on an international list of critically endangered primates in the Americas.

    Last year, Caquetá's local government directed Pacific Rubiales Energy, an oil company, to fund a $220,000 ecological study of the monkey. The project, one of Colombia's largest conservation efforts directed at a single animal, is being led by Defler, National University geneticist Marta Bueno, and colleagues. Since the discovery, García has started a conservation group called Herencia Natural, "natural heritage," that teaches schoolchildren about the red-bearded titi. This year, he saved up to buy a truck onto which he painted the monkey's profile.

    But he has grand ambitions. He hopes that the Colombian government will mandate reserves, reforestation of river banks, maybe even a carbon-trading plan. Perhaps, he says, his monkey could be the charismatic species that leads to a "change in the whole economic model that governs the landscape."

    But García has returned several times to a patch of trees where his monkeys lived, only to find it burned away and the monkeys gone. "What did they do? Did they migrate?" García wonders.

    With his T-shirts, guidebooks, and big smile, García is becoming a familiar presence around Caquetá's schoolrooms and vestigial forests. "I am really finding myself" as a conservationist, he says. "But I don't know if I will save this monkey."

  6. Coca Science Seeks an Answer in Kilos

    1. Antonio Regalado

    The scientists who work at the Pijaos ranch have two main goals: to perfect ways to kill the coca plant and to estimate exactly how much cocaine is produced in Colombia.

    Illegal crop.

    U.S. environmental engineer Ingrid Simon Calvo among coca plants.


    HACIENDA LOS PIJAOS, COLOMBIA—The noisy prop plane rumbles over the Andean highlands, crosses the muddy scrawl of the Rio Magdalena, and finally touches down on a grass runway protected by a steep ring of hills. This is the Pijaos ranch, home to the Experimental Coca Cultivation Project, the world's only coca research station. The Colombian and U.S. scientists who work on this police base have two main goals—to perfect ways to kill the coca plant and to estimate exactly how much cocaine is produced in Colombia. Their study of varieties, yields, and growing conditions supports the U.S. State Department's efforts to produce a single weighty number each year, an estimate of global cocaine output.

    Millions of dollars in U.S. military antinarcotics aid rest on this calculation, including support for Plan Colombia, which took the war on drugs into Colombia's coca fields in 1999. In July, the estimate of Colombia's potential output of pure cocaine stood at 175 metric tons per year, down 8% over the previous year, according to the United States. Colombia, once the world's largest cocaine producer by far, has fallen behind Peru.

    The Pijaos resea rchers work in obscurity. Their target is an enigma, too: In 2012, only four articles were published on the basic biology of the coca plant. Charles Helling, a retired U.S. Department of Agriculture scientist now in Beltsville, Maryland, says that when Pijaos was picked as the site for joint Colombian-American coca research in 2006, the literature still mostly consisted of 19th century ethnobotanical studies and reports from the Coca-Cola Company, which included cocaine in its original drink recipe. "It's basically an illicit plant. There is almost no one else doing research with it," Helling says.

    The Pijaos staff "replicates what the campesinos are doing," says Ingrid Simon Calvo, an environmental engineer and scientific adviser to the U.S. State Department's Narcotics Affairs Section. "If they use more fertilizers, then we do. If they add urea, we add it … and see if it increases yield." Since arriving at Pijaos in 2009, Simon Calvo has become familiar with a combination of soil and growth hormones that yield the most cocaine. "But we wouldn't publish it," she says.

    Rows of coca plants are laid out alongside yucca, banana, and corn. They're used to calibrate multispectral cameras on U.S. Drug Enforcement Agency airplanes that detect coca plants by their light signature. Satellite images, studied by a branch of the CIA that once tracked Soviet grain harvests, are also used to monitor cultivation. But estimates remain slippery. One reason: Farmers have begun to grow coca on smaller or more irregular plots or under trees in an effort to confuse image interpreters.

    Last summer, the United Nations produced an accounting that showed a rise in Colombia's potential cocaine production. The White House responded by putting out a press release restating its own figure, which that year had shown a steep fall of 25%. James Story, director of the Narcotics Affairs Section of the U.S. Embassy in Bogotá, says what's important is that both the U.S. and U.N. figures show a slow decadelong decline. "We think the science definitely gives us the trend, not an exact figure."

    The Pijaos lab plays a little-known, but critical part in Colombia's effort to combat guerrillas, because cocaine profits finance 80% of their activity, Story says.

    One line of research studies farmers' attempts to counter Plan Colombia. During the last decade, drug syndicates began bringing in tankers to spray crops with sugar water, believing it blocked the herbicide. "We needed to find out if that was just an old wives' tale," Helling recalls. Although washing does reduce the effectiveness of the herbicide, Helling found that sugar didn't have any additional effect. "So you'd kind of encourage them to do that; it's a waste of time."

    "Science underpins every effort" at Pijaos, Helling says. But the work has not touched on one hotly debated aspect of Plan Colombia: whether its use of herbicides could harm people. Colombian police planes annually spray about 100,000 hectares with Monsanto's Roundup (glyphosate), which blocks plant growth. It is applied at rates that bump up against limits recommended by the U.S. Environmental Protection Agency. Many fear that the herbicide could harm farmers.

    But Helling says his studies found that a lower rate of application was significantly less effective. As a result, leaders of Plan Colombia have resisted calls to cut back. "We know there is no health impact of glyphosate," says a U.S. embassy official in Bogotá.

    Meanwhile, the cat-and-mouse game with growers continues. Simon Calvo says this year Pijaos researchers were using their plantations to study whether more frequent applications of lower herbicide doses might actually work better at killing the plant. The goal, as always, is to use science to "break the cycle" of cocaine production.

  7. Public Health

    The Pertussis Paradox

    1. Arthur Allen*

    The introduction of a safer vaccine has inadvertently led to a frightening spike in the deadly disease commonly known as whooping cough.

    Hairy situation.

    Sausage-shaped B. pertussis lodges into cilia in the respiratory tract.


    When California reported more than 9000 cases of whooping cough in 2010, public health alarm bells rang far and wide. A childhood disease vanquished decades ago by a vaccine was resurgent. Major outbreaks of the disease, properly known as pertussis, soon surfaced in several other states, including Minnesota, Washington, and North Carolina. Something was wrong, very wrong.

    Kathryn Edwards, a vaccinologist at Vanderbilt University in Nashville, and many of her colleagues realized that the safer pertussis vaccines they helped usher in in the 1990s had come at a steep cost: They do not create immune protection as long-lasting as the vaccine they replaced. "It's humbling and kind of depressing," says Edwards, whose own daughter had suffered serious side effects from the old-fashioned vaccine. "I spent so much of my time and my life working on this. … We were so excited that we had the answer, and now it isn't really the answer."

    The old shot had cut the number of annual cases of whooping cough in the United States to a low of just over a thousand in 1976. But as the Centers for Disease Control and Prevention (CDC) in Atlanta prepares its final tally of U.S. cases in 2012, the number is closing in on 50,000, the highest since 1955, with at least 18 deaths and hundreds of hospitalized infants. Once-rare outbreaks are also common among vaccinated children across Europe, Australia, and Japan.

    The old whooping cough vaccine, known as DTP, contained killed whole pertussis bacteria—Bordetella pertussis—as well as detoxified diphtheria and tetanus particles to protect against those diseases. In the newer vaccines, the pertussis component includes only purified pieces of that organism. Intensive studies are under way to try to understand why the safer "acellular" vaccines, dubbed DTaP, don't protect for as long. Already, the studies have uncovered features of both the bacteria and the immune response to it that may be to blame. Other efforts are focused on salvaging the long-term efficacy of the old vaccine without restoring its dangers. But vaccine researchers know that solving the problem will not be easy.

    Less is less

    The original DTP vaccine, introduced in the 1940s, has been administered to children billions of times. But it frequently caused high fevers and seizures, which rekindled an antivaccine movement that had been quiet for half a century. In the 1980s, parents who blamed DTP for harming their children successfully sued manufacturers, leading many vaccinemakers to leave the market, although studies showed that permanent brain damage supposedly linked to the product was extremely rare and perhaps never directly caused by the vaccine. "People used to get up at scientific meetings and shout, 'You're killing our babies!'" recalls Alison Weiss, a microbiologist at the University of Cincinnati in Ohio.

    The actual side effects were soon linked to a powerful immune stimulant called endotoxin, contained in the cell membrane of the pertussis bacteria. This substance was removed from all the DTaP vaccines, which replaced DTP in the United States and other wealthier nations in the late 1990s.

    The new vaccines seemed just as effective, without the side effects. "Our nurses did home visits and administered randomized shots. They could tell with 100% certainty who got whole-cell and who got DTaP," Edwards says. "It was pretty remarkable—they were much less reactive. And they made antibody responses that were comparable or even higher than the whole-cell vaccine." Today, five doses are given to kids between the ages of 2 months and 5 years, and a booster shot (with a slightly reduced dose) is administered around age 12.

    The mounting bad news about pertussis outbreaks has caused great consternation among health officials, who are acutely sensitive to public distrust of vaccines—in no small part because of the old DTP's problems.

    Bruce Gellin, director of the National Vaccine Program Office at the U.S. Department of Health and Human Services, emphasizes the irony. "The DTP shot was the origin of the modern antivaccine movement, which led to a whole cascade of events, including a new vaccine that was less reactogenic—but as it turns out, at a cost," Gellin says. Adds epidemiologist Thomas Clark of CDC's Meningitis and Vaccine Preventable Diseases Branch: "We have acellular vaccines because people doubted the safety of whole-cell vaccines. We don't want them to doubt the effectiveness of our pertussis vaccines."

    It took several years after DTaP came to market before its limitations became clear. The reason: The immunity that it generates wanes slowly, as Clark's group at CDC showed in The Journal of the American Medical Association last November. They found that the acellular vaccines were solidly effective in the first year. But protection steadily declined over 5 years—as other studies have also shown. They revealed that children who received even a single dose of whole-cell vaccine were more than twice as likely to remain disease-free during an outbreak as those who received only acellular vaccines when they were infants. "These studies say the vaccine is the problem," Weiss says.

    Untangling why has been difficult, because researchers don't fully understand how pertussis vaccines work. Even with the whole-cell pertussis shot, the bacterium often infected adults, blood sera studies have shown, but they usually did not get sick or did not realize that their coughs were due to pertussis. "It's amazing how little we understand about pertussis and our immune response to it," says microbiologist Tod Merkel, who heads the respiratory and special pathogens lab at the Food and Drug Administration (FDA) in Bethesda, Maryland.

    The whole-cell shot contained more than a dozen different antigens, the particles that stimulate the creation of antibodies. Acellular vaccines in use around the world today contain between one and four of the antigens, including an important substance called pertussis toxin. The two vaccines now used in the United States also contain the pertussis surface proteins filamentous hemagglutinin antigen (FHA) and pertactin.

    The acellular vaccines generate high levels of antibodies to these proteins—but not all of those antibodies seem to be crucial for immunity to the disease. In trials held in Sweden and Germany, for example, whole-cell vaccines proved effective at preventing disease even while producing lower antibody levels to pertussis toxin and FHA.

    Pertussis "yanks the chains of the immune system," says the University of Cincinnati's Weiss. "It directs the immune system in the wrong way." FHA, for example, stimulates production of interleukin-10, a chemical that stimulates antibody production but suppresses a healthy response to bacterial infections.

    Endotoxin, in contrast, appears to be key to an effective vaccine. Although endotoxin triggers the high fevers and other adverse reactions caused by the whole-cell shot, it also sparks a hearty "innate" immune response. Unlike the adaptive immune system that produces antibodies against specific invaders, the more primitive innate immune system mounts attacks against, say, all Gram-negative bacteria like pertussis. So this nastier part of the bug may account for much of the old DTP vaccine's longer-lasting effects.

    Some studies suggest that B. pertussis is exacerbating a bad situation by mutating around DTaP, foiling the vaccine even during the period it stimulates a robust response. New pertussis strains recently found in the United States, France, and Australia, for example, lack pertactin, a key vaccine component. In a particularly concerning finding reported by Clark's CDC group in the 7 February issue of The New England Journal of Medicine, it found pertactin-negative strains in 11 of 12 infants hospitalized during a recent outbreak in Philadelphia, Pennsylvania. "You don't find perctactinless isolates in our historic collection," Clark notes.

    DTaP 2.0

    Reversal of fortune.

    U.S. pertussis cases have steadily climbed in the DTaP era.


    For now, public health officials are trying to deploy the existing vaccine more effectively. Because pertussis presents the most profound risk to unimmunized infants, CDC's Advisory Committee on Immunization Practices (ACIP) last year recommended that pregnant women receive a booster version of DTaP. The hope is that the booster will help protect the babies for at least their first year by preventing infection in the mothers. Maternal antibodies may also pass through the placenta and breast milk and directly protect the baby, too. Unpublished British data show that an intensive maternal vaccination program begun there last October has protected infants well.

    But the recent outbreaks show that older children need longer-lasting immunity. A proposal to give adolescents a second booster—for a total of seven pertussis shots between birth and age 16—was tabled at the June meeting of ACIP because of a negative cost/benefit assessment. The most attractive solution is clearly an improved DTaP.

    "We have to go back to research on pertussis, which has not been a priority in the recent past because we thought the problem was more or less solved," says Stanley Plotkin, a renowned vaccinologist who consults with SanofiPasteur, a major producer of acellular vaccines. Although the number of labs working on pertussis has shrunken, a core of experienced researchers remains, and they have better tools than they did in the 1990s, including a new animal model. Merkel and his colleagues last year showed that the baboon provides a far more accurate reflection of human immunity to pertussis—and a better testbed for vaccines—than the macaque monkeys in which earlier work was done.

    Academic researchers and industry are pursuing a variety of approaches. New ingredients might include adenylate cyclase toxin, a protein that helps B. pertussis establish an infection. Novartis, of Basel, Switzerland, is looking into the reintroduction of a vaccine containing a genetically modified pertussis toxin. The vaccine performed well in trials in the 1990s, but was never licensed in the United States or most of Europe. Other researchers are eyeing the immune system stimulator, or adjuvant, in the current vaccine. It uses alum; perhaps a newer adjuvant could breathe life into the cell-free vaccine.

    Some researchers want to refurbish the whole-cell vaccine so it packs a punch without causing harm. Microbiologist Camille Locht and his colleagues at INSERM, the French biomedical research agency, have developed a live pertussis vaccine in which three of the pertussis toxins have been genetically deactivated or removed. Sprayed into the nose, the vaccine protected mice well and produced a healthier immune response than acellular vaccines. It has so far been safely tested in a small number of adults. James Cherry, an infectious disease specialist at the University of California, Los Angeles, with colleagues Rachel Fernandez of the University of British Columbia, Vancouver, and Peter Sebo of the Academy of Sciences of the Czech Republic in Prague, are working on a version of the killed whole-cell vaccine that contains genetically detoxified endotoxin.

    Formulating a new vaccine and getting it licensed for use in infants presents sobering challenges, however. Changing pertussis ingredients could alter the effectiveness of the tetanus and diphtheria components in the DTaP shot—which in some places also contains hepatitis B, inactivated polio, and Haemophilus influenza type b antigens. All told, bringing a new vaccine to market could cost several years and hundreds of millions of dollars. Companies that profit from current pertussis vaccines may balk at the investment.

    But until government and industry commit to the effort, CDC's Clark and other epidemiologists suspect that pertussis cases in countries that use DTaP will continue to climb.

    • * Arthur Allen is a writer in Washington, D.C.

  8. Human Evolution

    How a Fickle Climate Made Us Human

    1. Ann Gibbons

    Researchers are drilling for clues to how dramatic changes in African rainfall and vegetation shaped our species.

    Humans, like children, are the products of their environment. The famous anatomist Raymond Dart recognized that back in 1925, when he described the first hominin skull found in Africa. The evolution of this "Man-Ape," he wrote, markedly differed from that of earlier apes. While apes lolled about in "luxuriant" tropical forests that posed relatively few survival challenges, the "Man-Ape" had to compete for scarce food and water with saber-tooth tigers and other dangerous beasts of the arid savanna—and ended up sapient. "For the production of man a different apprenticeship was needed to sharpen the wits and quicken the higher manifestations of intellect—a more open veldt country," Dart wrote.

    Wellsprings of data.

    Researchers are drilling deep into Africa's Great Rift Valley to get detailed climate data.


    This "savanna hypothesis" suggested that as a drier climate caused grasslands to spread, our ancestors moved out of the trees and began walking upright in order to spot predators and prey in the waist-high stems. That freed their hands to use tools and spurred the development of big brains.

    Today, no serious paleoanthropologist believes that particular evolutionary tale. But Dart's hypothesis was the first of many to propose that shifts in climate and environment made humans who we are. The idea has become practically received wisdom even though there has been little direct evidence to support or falsify it. True, researchers have extracted precise records of past climate from seafloor sediments and ice cores. And they have noticed that fossils and environmental clues on land also suggest that some climate shifts coincide with changes in human ancestors.

    But correlation is not causation, and only "a circumstantial case" has been made for climate as the engine driving human evolution, says paleooceanographer Peter deMenocal of Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York. Even correlation can be elusive: Syncing fossil discoveries with offshore climate records thousands of kilometers away has proven challenging. Most stories of how environmental change shaped our evolution have been "mainly fantasies of the past," says paleoanthropologist Andrew Hill of Yale University. "They are not proven."

    That is beginning to change, however, as researchers deploy new tools to reconstruct climate and environment right where ancient hominins—the ancestors of humans but not other apes—once lived. This summer, for instance, a truck with a drilling rig has worked its way up the Rift Valley of Kenya, extracting sediment cores from dried-out lakebeds next to key fossil sites. Specialists are already analyzing a core drilled last year at Olorgesailie in Kenya (see story, p. 476).

    Such detailed, localized work may put some theories to rest and breathe new life into others, including a revived version of the savanna hypothesis. "For the first time, we'll be able to frame the question as: 'How did hominins respond to the environment they lived in' rather than as responses to global or Northern Hemisphere events," says geologist Craig Feibel of Rutgers University in New Brunswick, New Jersey.

    Grass roots

    If the past is a foreign country, as historians say, then the prehistoric landscape is an alien world. Using a host of climate indicators, geologists have uncovered evidence of dramatic events that changed the planet in the past 7 million years, showing that the African landscape has evolved as dramatically as the anatomy of hominins. In the words of Dart, our ancestors' "eyes saw, their ears heard, and their hands handled," terrain far different from today's.

    About 4 million years ago, for example, the Turkana Basin in Kenya—home to seven hominin species, including our direct ancestor Homo erectus—was covered by a vast inland sea, three times bigger than the lake there today. At the continent's northern edge, the Mediterranean Sea dried up between 5 million and 6 million years ago, decreasing the circulation of moisture over Africa and Europe, according to a 2010 National Research Council report. This may have amplified a cooling and drying trend that had already started in Africa 6 million to 8 million years ago, according to oxygen isotopes from marine and ice cores.

    That long-term drying trend, which began at about the time when the human and chimp lineages diverged, tempted some researchers in the 1990s to propose a revised savanna hypothesis: Drier, cooler climates thinned the forests of Africa, perhaps driving hominins out of the woods to scurry upright across open grasslands between patches of trees in search of food.

    Then, new fossil discoveries challenged that idea. Paleoanthropologists found three very early, upright hominins that, according to clues left in the fossil sites, apparently lived in the woods between 7 million and 4 million years ago: Ardipithecus ramidus from Aramis, Ethiopia; Orrorin tugenensis from the Tugen Hills of Kenya; and Sahelanthropus tchadensis from Chad. For example, researchers found fossils of Ar. ramidus with fossilized wood and seeds, and near fossils of woodland monkeys, parrots, and snails. With hominins walking in the woods, the savanna hypothesis bit the dust.

    Now, however, a half-dozen geologists are resurrecting the importance of grasslands in human evolution once again. This time, however, the theory has to do with how human ancestors used the savannas for food, not hunting and rambling.

    The renewed savanna hypothesis has its roots in evidence that as African climate dried out 6 million to 8 million years ago, the makeup of plant communities was also shifting, says geochemist Thure Cerling of the University of Utah in Salt Lake City. That's because the amount of carbon dioxide in the atmosphere began to decline 10 million years ago, giving a boost to plants that use the more efficient C4 photosynthetic pathway; most of those plants are grasses and sedges, whereas woodland plants such as trees and shrubs usually rely on the older C3 pathway. Grasses and other C4 plants went from carrying out 1% of the photosynthesis in the tropics 10 million years ago to 50% today.


    As went plants, so went the animals that grazed on them: By 6 million years ago, C4 grasses had replaced C3 plants as the most significant component in the diet of African grazers, Cerling says, according to studies of carbon isotopes in the tooth enamel of horses, elephants, antelopes, and other animals.

    This suggests that hominins were born when grasses were on the rise. In fact, Cerling and his colleagues think that the first hominins had more grass in their environment than initially proposed—40% to 60% of the vegetation at nine Ar. ramidus fossil sites was C4 plants, Cerling suggests (Science, 28 May 2010, p. 1105).

    Recent data now show that later hominins responded to the rise of grasses by broadening their diets. Species that arose more than 4 million years ago, including Ar. ramidus and the oldest australopithecine, Australopithecus anamensis, subsisted on an apelike diet of at least 90% leaves and fruits from C3 plants, Cerling and his colleagues reported in June in the Proceedings of the National Academy of Sciences. By 3.5 million years ago, a descendant of Au. anamensis—Au. afarensis, whose most famous member is the skeleton named Lucy—apparently adapted to the widespread grasslands by also munching on many C4 plants, according to Cerling's analysis of carbon isotopes in the tooth enamel of seven hominin species. Au. afarensis—a leading candidate for the ancestor of Homo—and another hominin, Kenyanthropus platyops, still ate mostly C3 woodland plants, but about 22% of their diet was also made up of these C4 plants, making them the hominins with the most varied menu. Their meals included grasses and sedges such as water chestnuts and papyrus and perhaps animals that fed on those plants.

    This appetite for grasses apparently left its mark on Australopithecus anatomy: Most members of the genus had much larger molars and premolars than earlier hominins. Such big choppers would last longer than small ones when chewing on gritty grasses and abrasive sedges.

    Where the hominins roamed?

    New data suggest that grassland environments were important in hominin evolution.


    Given that grasses were abundant in all hominin habitats for so long, "the savanna hypothesis is alive and well," Cerling says. The grasslands may have had other evolutionary impacts, too, although the revived savanna hypothesis is so new that paleoanthropologists are just beginning to consider it. They note that the earliest hominins walked upright, but with a variety of odd gaits; the savanna may have favored adaptations for more effective walking and running, such as an arched foot and nonopposable big toe, that led to the typical human gait (Science, 11 February 2011, p. 750). "Cerling's data are causing us to refocus on the link between environment and adaptation," says paleoanthropologist Carol Ward of the University of Missouri, Columbia. "But we still have more questions than answers."

    Cerling's savanna hypothesis "is not Dart's savanna hypothesis," says Richard Potts, a paleoanthropologist at the Smithsonian Institution in Washington, D.C. That's partly because geologist Cerling uses a broader definition of "savanna" than many paleoanthropologists. But it's also because the hominin most specialized for the grasslands was not on the line leading to Homo. The "Nutcracker Man," Paranthropus boisei, used its giant molars to crunch on a diet of 75% C4 grasses and sedges, according to recent isotopic studies—and it died out about 1.2 million years ago, Lamont-Doherty's deMenocal notes. They "weren't the successful ones."

    Burst of speciation

    Over the years, other hypotheses connecting human evolution to climate have also come and gone. For example, in the 1980s, Yale's Elisabeth Vrba suggested that dramatic shifts toward a cooler, drier climate in the East African Rift Valley between 2.7 million and 2.5 million years ago sparked bursts of rapid extinction and speciation in grazers like antelopes, as well as in hominins. But this turnover-pulse hypothesis—so named because pulses of climate change were thought to spark big turnovers in species—faded after later studies showed that the shift in species happened more gradually. Still, the idea's not dead yet: Arizona State University, Tempe, paleoanthropologist Kaye Reed has spotted another burst of speciation about 3 million years ago at Hadar, Ethiopia. There, 10 new species, including camels and hoofed grazers, appear just before H. habilis replaced Au. afarensis.

    Although Vrba thought that drying had sparked rapid speciation, other researchers have noticed that new species of hominins seem to appear during wet, humid periods. For example, studies of lake sediments in 10 East African rift basins suggested that the overall cooling and drying trend of the past 8 million years was interrupted by at least three humid periods when deep lakes filled, which tie in with the birth of new hominins. So did cool, dry climates or wet, humid ones shape the evolution of hominins?

    Potts has a different answer: It was all these changes, fluctuating wildly, that produced humans.

    Creatures of change

    Potts proposed 16 years ago that the key adaptation of the human lineage, manifested in everything from big brains to culture, is adaptability: Individuals who could survive in wet woods as well as dry grasslands fared better than those specialized for one or the other. He argues that the dramatic fluctuations of the ancient African climate shaped human nature, allowing our species to eventually thrive in all sorts of environments worldwide.

    Deep-sea cores suggest that "the first appearance of every major genus in our evolutionary history, the origin of every major stone technology, happens to fall in long periods of high climate variability," Potts says. He ticks off in rapid fire the innovations of such periods: the birth of Australopithecus, H. habilis, H. erectus, Paranthropus, and H. sapiens, plus the invention of the first stone tools 2.6 million years ago, the creation of more advanced Acheulean tool kits 1.8 million years ago, and the first Middle Stone Age technologies 300,000 years ago. Each event is correlated with a period of high climate variability, such as wet and dry cycles, Potts says. For example, the span between 2.5 million and 2.7 million years, which Vrba noted had such turnover in species, cycled between extremely wet and extremely dry times.

    But the evidence for those fluctuations comes from predictions from climate models and from marine sediments collected far from fossil sites. On the African continent, many local factors may have modified climate, such as rain shadows created by mountains or differences in altitude. Some basins may have been buffered from climate change and served as refugia.

    Deep roots.

    As shown in this stylized diagram of ancient lake deposits, fossils erode out of lake margins and escarpments, but geologists drill in the deepest part of ancient lakebeds, where the most complete climate record lies.


    The few cases where fossils are paired with local climate data offer tantalizing hints of support for Potts's idea. For example, layers of ancient sediment from outcrops in the Tugen Hills in Kenya reveal signs of wet and dry cycles, according to work by Yale's Hill and geologist John Kingston of Emory University in Atlanta. They collected diatoms, siliceous blue-green algae that grow in fresh water but vanish from sediments when a lake dries up. These tiny tracers mark when ancient lakes were full or dry, and showed that the Baringo Basin repeatedly filled and emptied every 20,000 years between 2.58 million and 2.69 million years ago. This was a response to cyclical changes in the orientation of Earth's axis as it orbits around the sun, the Milankovitch cycles, which in Africa create alternating wet and dry conditions. These cycles are the "pacemakers of African climate," deMenocal says.

    The repeated shifts had a "kaleidoscopic" effect on animals in the basin, breaking up communities as the lakes filled, then allowing new mixes of species to reassemble when the lakes shrank, says Hill, whose team noted these shifts in fossils. One species that was part of the mix was Homo: The oldest Homo fossil was found just above a layer with diatoms, dating to 2.5 million years ago, suggesting that our genus arose just after the wet and dry cycles intensified in the Baringo Basin (Science, 4 February 2011, p. 540).

    To nail down such links, however, researchers need local evidence, for example that climate changes preceded bursts of speciation, as predicted by the turnover-pulse hypothesis. The climate record near fossil outcrops is often incomplete. However, fine-scale evidence of such changes can come from the sediments that piled up in the deepest part of ancient lakes, which trap chemical isotopes, pollen grains, charcoal, and other bits of detritus that offer telltale signs of past climates. "These lake sediments are like a metronome. They're accumulating all of the time," says paleolimnologist Andrew Cohen of the University of Arizona in Tucson. Adds Feibel: "Getting a lake record of environmental variability literally a few kilometers from the actual [hominin fossil] sites" can offer "an unprecedented perspective on when and how environmental fluctuations actually impacted these landscapes and habitats."

    That's why this year, after 8 years of planning, an international team is drilling holes in six ancient lakebeds in Kenya and Ethiopia, says Cohen, who directs the $5 million Hominin Sites and Paleolakes Drilling Project. In June, the group drilled down 228 meters and extracted cores in the Baringo Basin, hoping to sync the local wet-dry cycles with records from deep-sea cores, and to see local changes as early as 3.4 million years ago. Farther north, in the Awash valley, cores will test whether dry climate preceded the turnover in grazers 3 million years ago. If the cores don't show that climate changes intensified, the turnover-pulse hypothesis would be falsified in that lake basin. Conversely, if signs of grasses are common, the data may strengthen the revised savanna hypothesis.

    The same drill rig is also taking cores from the habitats of other ancient hominins, including the site where a 1.6 million-year-old skeleton of H. erectus was found in the Lake Turkana Basin. The team also will core two lake basins in Ethiopia and Kenya that cover the time span drilled at Olorgesailie—the past 500,000 years, when H. sapiens was born. "Each of these places will give us an interesting time slice through human evolution," Cohen says. The cores will enable researchers to "ask some of the most existential questions of our time," he says: "What it means to be human and what were the environmental constraints on why we are the way we are."

  9. Out of the Kenyan Mud, an Ancient Climate Record

    1. Elizabeth Pennisi

    Scientists gather for a first look at a fresh sediment core, hoping that it will offer hard data linking environmental change to human evolution.

    MINNEAPOLIS, MINNESOTA—When Richard Potts, Anna Behrensmeyer, Alan Deino, and Richard Bernhart Owen get together, it's usually at camp at Olorgesailie in Kenya's Great Rift Valley. The paleoscientists labor for hours in the hot sun, chipping away at exposed rock outcrops to develop a timeline for artifacts and other relics of the human ancestors who once lived nearby. But on a cold spring day earlier this year, they gathered with a dozen other researchers in a small lab at the University of Minnesota to analyze something quite different: 190 meters of mud, sand, and gravel cored last year, from what they hoped was once a lakebed 20 kilometers from their outcrops.

    The team had never tried to drill a core before and hadn't even known for sure that a lake ever covered the area. But as the researchers kicked off their "core sampling party," they hoped that the mud would resolve into thousands of distinctive layers, each representing a different climate regime, ultimately reaching back 500,000 years. The goal: to test ideas about the role of climate variability in human evolution, by getting a continuous record of climate indicators from a place where hominins lived and died (see story p. 474). The project "has high potential to reconstruct the long-term history of environmental change," says team member Vanessa Gelorini, a paleoecologist at Ghent University in Belgium.

    Although everyone eagerly anticipated what might be hidden in the 139 half-meter- to 3-meter-long cylinders of sediment, the group was anxious. The work required difficult on-the-spot decisions and taking hundreds of samples—chores best accomplished by everyone working together at the same place at the same time, says Potts, the Smithsonian Institution National Museum of Natural History (NMNH) paleoanthropologist who has led the Olorgesailie project since 1986 and raised $450,000 in private funding for the drilling and party. But cores don't come with labels, and everyone had questions. Do we have a truly continuous record? How far back does it go? Can we date the layers? In other words, will this investment give us the data we seek?

    Digging for climate proxies

    At the field site, Olorgesailie, researchers have been digging out artifacts and fossils since Louis and Mary Leakey first explored it in the 1940s. Since 1986, geologists have tried to extract clues to ancient climates from the outcrops (Science 23 March 1990, p. 1407). But the outcrops are not a continuous record of the past: They represent the period from 1.2 million to 500,000 years ago and then pick up again from 320,000 years ago to the present. Rock formed during the gap has eroded away.

    Yet during those missing millennia, humans moved from a culture limited to stone axes to the so-called Middle Stone Age, marked by new tool innovations and perhaps more sophisticated social interactions. Potts proposed more than a decade ago that an increase in the variability of the climate during that time shaped human evolution by ratcheting up hominins' genetic and phenotypic plasticity, so that they could survive in a broad range of conditions. Those changes prepared our ancestors to eventually spread worldwide.

    But Potts's theory couldn't be tested without a climate record from the missing years. Where might it be preserved? One possibility was the Koora Valley 20 kilometers to the south, which was connected by a shallow depression to the Olorgesailie site. Potts and his NMNH colleague Behrensmeyer speculated that sediments eroded away at Olorgesailie had washed into the channel and down to the basin. If there had been a lake there, the researchers would be in luck. Lake bottoms typically accumulate sediments year after year, and, hidden from the sun and weather, those sediments are often well-preserved. "We didn't know for sure that there was going to be a lake," Behrensmeyer recalls. "If it were just a pile of pumice or volcanic ash, it wouldn't have preserved the environmental signals."

    Assembly line.

    In a week, Richard Potts, Anna Behrensmeyer, and their colleagues studied all the core's sections.


    To test the idea, Potts secured funding from several private foundations. A local drilling company spent September 2012 digging out two cores on the Koora Valley and shipped them here to the National Lacustrine Core Facility (LacCore), a lake core processing and storage lab supported by the U.S. National Science Foundation.

    Guest of honor

    At the core party, technicians begin slicing each 4-centimeter-wide core section lengthwise down the middle, enabling researchers to mine the sediment for a plethora of indicators of ancient climate. For example, different types of plants fractionate the two isotopes of carbon, C-12 and C-13, differently. So analyses of plant waxes extracted from the sediments can indicate whether dry-adapted grasses or moisture-loving vegetation thrived. Bits of calcium carbonate, found in some soils, contain isotopes of oxygen (O-16 and O-18) that can reveal the temperature at which the carbonate formed. Certain clays indicate aridity.

    Each material provides a proxy for what the environment was like during the formation of a sediment layer. Individually, however, the proxies and layers "are like blind men feeling the elephant," Potts says. Only by combining them can researchers assemble a cohesive picture. And that depends on accurately dating the sediments. At this point, the team isn't even sure that the core stretches to the sought-after 500,000 year time point. Dating is Deino's job, and that's why at this party he is the guest of honor. If he can find volcanic material, he can use radiometric dating to determine when it formed, and so provide a chronology for the cores, pegging the ups and downs of each climatic indicator to actual dates.

    A beefy, taciturn geochronologist at the Berkeley Geochronology Center in California, Deino commands a dedicated computer terminal and one of the few stools in the lab—almost everyone else has to stand. He also gets first dibs on one-half of each sliced core. (The other halves are archived virtually untouched.) The cutaways reveal a panoply of colors and textures, ranging from midnight black to sunrise yellow, from fine clay grains to small pebbles. In some sections the layered striations are so narrow that they are barely discernible by the naked eye.

    Deino also receives color scans of each core, which he enlarges to search for dark areas that signal volcanic rock and ash. In one section known as 3A 4Q1, he pokes around with a metal spatula, exposing small, angular pieces of pumice. The angularity signals that these fragments are fresh from an eruption, rather than being deposited sometime after formation. They prompt a rare smile from Deino. He's taken dozens of samples, but none as promising as this one. "It's yelling 'Date me, date me,'" he says, digging out a chunk several centimeters long and scooping it into a bag.

    Hours earlier, LacCore curator Anders Noren had urged the researchers to sample very conservatively, preserving as much core as possible for the future. But Deino takes as much as he wants, no questions asked, sometimes up to 300 grams at a time.

    When Deino said he has "'lots to look at,' I breathed a huge sigh of relief," says team member Peter deMenocal, a geochemist at Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York. Back at his lab, Deino will start by dating the best 10 samples that span the core from top to bottom, giving him a rough estimate of the overall sedimentation rate. Then he'll date more samples to boost the resolution. All other analyses will be pegged to the resulting chronology. "Al, all eyes are on you," deMenocal tells Deino.

    Lake, or no lake?

    Well, not all eyes. There's also the question of whether the sediment actually came from a lake, and so is likely to provide a continuous record. An initial look at the cores in the field suggested it had, but now came the real test.

    Behrensmeyer and Owen, who has come all the way from Hong Kong Baptist University, hover over each core section to describe the texture, color, and layering. Such baseline data will help others know where to look for the climatic indicators they study.

    Behrensmeyer studies enlarged photographs of the core for irregularities such as animal burrows or pieces of pumice, then pulls a dental pick from her hip pouch to tap the soil at those spots. Where the core seems to change character, René Dommain, a paleoecologist from the University of Greifswald in Germany, dissolves a tiny speck onto a slide and examines it with a petrographic microscope, whose polarizing filters help reveal the mineral composition of the smeared sediment.

    The smear slides reveal little sign of life in the core's youngest, uppermost layers. Then a slide taken at 37 meters down is littered with diatoms, tiny algae with distinctive siliceous shells that grow in specific environments. "We have a lake," Owen announces to the group; they erupt into a cheer. Potts and Behrensmeyer now know that their predictions are correct.

    Ready and waiting.

    At the LacCore lab in Minneapolis, 1.5-meter-long sections of core await processing.


    In subsequent slides, changes in the mix of diatoms reveal an ever-more saline environment as the sediments get older. At about 44 meters down, diatoms peter out, perhaps indicating that the lake was temporary or too saline for diatoms. Dommain also records sightings of fossilized fungal spores, bits of other algae, phytoliths, charcoal, and pollen, all of which can record environmental dynamics. The presence of one colonial alga, Botryococcus, for example, indicates a shallow lake. Charcoal speaks to fires: The bigger the piece, the closer the fire was to the lake. "All this [variability] tells you it's not a stable environment," Dommain says.

    When the weeklong party finally breaks up, there is still plenty of work left. Over the next 18 months, the guests plan to complete their initial analyses and tie what they find to what they know from the outcrops. Ultimately, they'll develop a catalog of how the climate indicators changed over time, then attempt to model how climate changes affected the local ecosystem and the hominins who lived there. "We will have lots of stories" to tell, predicts Naomi Levin, a paleoecologist at Johns Hopkins University in Baltimore, Maryland. "But to figure out the importance for human evolution will take a lot more time."

  10. Wetlands

    Can Coastal Marshes Rise Above It All?

    1. Eli Kintisch

    As climate change causes sea level to rise, wetland scientists are struggling to predict which salt marshes will drown—and which might climb out of danger.

    WESTERLY, RHODE ISLAND—Biologist Marci Cole Ekberg plunges her shovel into a particularly gloppy spot in a mucky salt marsh near the Atlantic Ocean. Her goal: to drain one of many shallow pools that are creating dead zones in the expanse of otherwise dense grasses, a phenomenon that she's recently observed in more than a dozen other marshes around the state. She fears that the pools are an early consequence of the sea-level rise that is being driven by global warming and an ominous "glimpse of the future" for marshes in New England. Rising oceans will drown the grasses, she worries, eliminating rich habitats and leaving coastlines bare.

    Shovel ready.

    For conservationists in Rhode Island, restoring coastal marshes requires boots on the ground.


    Other researchers, however, are skeptical that the pockmarks are a result of climate change, saying winter ice or other causes may be to blame. And Rhode Island isn't the only place where researchers are debating what is really happening in salt marshes today and how the wetlands will fare in a future of higher seas. There's wide agreement that these salt marshes are among the ecosystems most vulnerable to rapid sea-level rise. But few researchers are ready to predict the fate of specific marshes; there's still too much to learn, they say, about how wetlands in different regions accumulate sediments that might allow them to outclimb rising waters and whether they can escape by migrating inland.

    Wetlands scientists are mobilizing to reduce the uncertainty. By building improved forecasting models and better monitoring systems—and studying wetland regions already experiencing dramatic sea-level rise—they're hoping to bring some clarity to a murky topic and identify practical steps to protect marshes. The overarching goal, says wetlands researcher Susan Adamowicz of the U.S. Fish and Wildlife Service in Wells, Maine, is to help managers "give marshes the best possible chance to outpace global sea-level rise."

    Wet benefit

    Although they're not the most glamourous biomes, the United Nations estimates that wetlands are one of the world's most valuable providers of "ecosystem services," such as storm protection, water filtering, and seafood production. They also help lock up as much as 450 billion metric tons of carbon globally, absorbing warming compounds that might otherwise leak into the atmosphere.

    Marshes have already experienced centuries of insults—such as pollution, overfishing, and draining for farming and development—that have disrupted the ecological systems that help keep them healthy. Now, rising temperatures are causing land-based ice sheets to melt and seawater to expand. Such changes have already helped push sea level up by an average of 1.4 to 3.7 millimeters per year since 1950, according to a 2010 study published in Science. (Other estimates vary.) Climate models predict that the trend will accelerate to 1 centimeter or more per year as Earth continues to warm. And even a few extra centimeters of water can mean the difference between life and drowning for marshes, which typically occupy a narrow coastal band that ends just above the high tide line.

    Faced with rising water, marshes have three options, says geologist Matthew Kirwan of the U.S. Geological Survey (USGS) in Charlottesville, Virginia: build in place by trapping and piling up new sediments, migrate to higher ground inland, or die. Predicting which path a marsh might take, however, requires understanding the interplay of a host of factors, including the biological traits of different marsh grasses and how wetlands construct muddy yet firm foundations from grains of sand, silt, and organic litter.

    A sinking laboratory

    Bayou blues.

    Louisiana's disappearing marshes offer a glimpse of how global wetlands may respond to rising seas.


    To get a glimpse of how these factors might shape marsh adaptability in the future, researchers have begun to scrutinize one wetland ecosystem already experiencing local sea-level rise: Louisiana's Mississippi delta along the Gulf of Mexico. There, natural and human factors are causing the land to sink relatively quickly, creating a natural laboratory that simulates a sea-level rise of 1 to 2 cm per year. That could be "what it's going to be like everywhere by the end of the century," says ecologist James Morris of the University in South Carolina, Columbia.

    Some delta marshes are adapting better than others: While grasses in a spot named Old Oyster Bayou have thrived, for instance, those in nearby Bayou Chitique have been largely submerged. The difference, researchers say, highlights the important role that an adequate supply of fresh sediment can play in marsh survival. While Old Oyster Bayou receives some 70 mg of fresh sediment per liter of river water, allowing it to outclimb rising Gulf waters, Bayou Chitique's sediment infusions are largely blocked by upstream levees, reducing the load to just 20 mg per liter. The "natural process has been interrupted and there's not enough sediment," Morris says.

    A 2010 modeling study that Kirwan and his USGS colleagues published in Geophysical Research Letters underscored the importance of sediment supply. In a scenario that included a rapid global sea-level rise of 1.25 m by 2100, the outlook for the 21st century was grim: "Most coastal wetlands worldwide will disappear," they concluded. But under slower scenarios, there was hope. Although marshes with low sediment availability fared poorly in the models, those with ample supplies often survived. A marsh's tidal range also played a role, the study found, with wetlands located in regions with larger gaps between low and high tide better situated to ride out sea-level rise, apparently because plants adapted for higher tidal ranges better withstand drowning.

    Trench warfare

    For conservationists, such studies suggest that it might be possible to help threatened wetlands adapt—for instance, by removing levees or dams to restore sediment, or even pumping in new mud. And in Rhode Island, the idea of ultimately aiding drowning marshes is what motivated Cole Ekberg, a biologist with the conservation group Save The Bay, to recently lug a shovel into a marsh here that is pockmarked with shallow grassless pools.

    The origins and meaning of the pools is the subject of local debate, some fierce. Cole Ekberg and others say that their spread is a relatively recent development, documented in just the last few years in the higher-elevation parts of marshes in Rhode Island, Connecticut, Massachusetts, and Maine. And she's been running a restoration experiment of sorts, draining the pools to see if the grasses come back. "It's the best part of the day when water begins to move," she says.

    Other marsh researchers are skeptical, blaming winter ice damage, invasive weeds, or geology. Mark Bertness, a marine ecologist at Brown University, sees "no evidence" of sea-level rise in the pools and says that the Save The Bay staff members are "well-intentioned but naàve."

    Bertness also wonders whether the focus on sea-level rise is diverting attention from more immediate threats. His own studies, for instance, have shown that overfishing has resulted in a boom in a population of crabs that chow on marsh grass, sometimes causing severe damage. "I was just dumbfounded what these crabs have done over a 2, 3-year period," he says. "Sea-level rise is going to come along, but this is happening now."

    No escape route

    All sides, however, appear to agree that if a marsh doesn't have a sediment source that will allow it to build up, "then the question becomes will it be able to migrate," Kirwan says.

    Increasingly, the answer is no. Marshes around the world are hemmed in by development that essentially blocks migration to higher ground. In many areas, the obstacles are concrete or stone sea walls built to protect seaside homes or industrial sites. In Europe and parts of Asia, studies have found that two-thirds or more of many shorelines have been "armored." Even sparsely populated sites can leave marshes little room: A 2000 study of Maine's lightly inhabited Casco Bay found that one-fifth of its shoreline was armored.

    Some researchers are beginning to look at ways to clear such obstacles. Around the Blackwater National Wildlife Refuge near Maryland's Chesapeake Bay, for instance, a coalition of conservation and government groups has embarked on an ambitious effort to identify potential obstacles and protect possible migration paths. The group is even eyeing pine forests and farm fields that may have the right topography and soil types to be converted to future marshes. The Nature Conservancy has launched a similar effort on Long Island in New York state, while Rhode Island officials, scientists, and activists are working on a statewide assessment to map out risks to wetlands under different scenarios.

    It could take decades to realize such forward-thinking efforts, planners say. In the meantime, scientists say that they need better ways to monitor how marshes are doing now. A good start, a team of USGS researchers argued in an April paper in Nature Climate Change, would be to create a global network of 14,000 relatively simple devices called surface elevation table markers. Secured to the ground beneath marshes, mangroves, and wetlands, they can register changes in the height of the marsh surface to an accuracy of 0.01 cm, more precise than surveys, LiDAR, or satellite readings. The authors say the network, which might cost $8 million to create, "would allow policymakers to prioritize wetland sites for intervention."

    That's a goal that Save The Bay's Cole Ekberg supports. "Someone might ask what's the point of protecting salt marshes anyway, if they're doomed in the long run," she says. "My answer is if we can extend their lives 20 or 30 years, it's a valuable investment."

  11. Geography

    Worth a Thousand Words

    1. Elizabeth Pennisi

    Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.

    In 1868, British soldiers lugged a 500-kilogram camera into the Ethiopian mountains—not to shoot snapshots, but to photocopy documents for headquarters. Occasionally, however, they trained the lens on their surroundings. Now, 145 years later, the antique photos provide a unique window into how climate change and other factors have affected Ethiopian ecosystems. By comparing the historic images with modern photos snapped at the very same spots, researchers are documenting biological shifts that might be otherwise invisible. And Ethiopia isn't the only locale captured in historic photographs: Researchers have also turned up valuable troves from China and the Arctic. The photographs represent "a very powerful ecological tool," says Isla Myers-Smith, an ecologist at the University of Edinburgh in the United Kingdom.

    Looking back.

    Pictures, such as this one of an 1868 British encampment in Ethiopia, are useful for environmental studies.


    Although repeat photographs of receding glaciers yield perhaps the most iconic images of climate change, before-and-after images also document more subtle biological shifts. Changes in forest or desert cover, acceleration of plant growth, and shifts in species can all show up. Realizing the potential of repeat photography, however, isn't easy.

    First, researchers must track down potentially useful historic images. Most photos dating back a century or more were taken for reasons other than documenting the environment, so just a handful may be relevant to, for instance, climate change. "You can do a lot of looking," Myers-Smith says. Then, scientists need to find out where the picture was taken and make the effort to return to the site. That may mean "hours of walking around looking for the 'right' bend in the stream or bump on the ridge," she says.

    But the effort can be worth it. Photo comparisons have yielded numerous insights and a few surprises. In these pages, Science takes a look at a few projects that use photos to go back in time.

  12. Advancing Seasons in China

    1. Elizabeth Pennisi

    Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.


    Repeat photography was a labor of love for Yin Kaipu. In 2004, at age 60, the botanist from the Chengdu Institute of Biology in China, decided to follow in the footsteps of American plant collector Ernest H. Wilson. At the turn of the 20th century, camera in tow, Wilson explored western China for Harvard University's Arnold Arboretum. Much later, Yin covered some of the same territory for his work and was excited to recognize places where Wilson had taken photographs. "The landscape that I saw had already gone through great change since Wilson's time," Yin says.

    It took him 7 years to gather 1000 of the historical photos, 400 of which had potentially telltale landmarks. Based on books that traced Wilson's travel routes, Yin plotted a course through the 753,300 square kilometers of Sichuan, Hubei, and Chongqing provinces. He estimated that, in advance, he could pinpoint each location to within 30 kilometers.

    Six years later—after raising $200,000; traveling on foot, horseback, motorcycle, and boat; and pushing his body to its limits—Yin had documented severe deterioration of the natural environment and a reduction in biodiversity, he says. The photos revealed climate change impacts as well. In one county, for instance, farmers plant rice a month earlier than they did 100 years ago. Elsewhere, the dates on the early and recent images showed that a spring flower, Primula, also blooms a month early.

    Early bloomers.

    In 1910, Chinese farmers were just planting rice in June; by 2007, fields are quite far along by that time of year.


    Yin is not the only repeat photographer combing China's landscapes. Conservation biologist Robert Moseley was exposed to the technique as an undergraduate in the 1970s, during a summer job in Idaho documenting how vegetation recovered from grazing. When he moved to the Tibet-Yunnan border for The Nature Conservancy in 2000, he turned to the method again, inspired by a magazine article with photographs taken in 1923 by National Geographic explorer Joseph Rock. With help from the National Geographic and Royal Geographical societies, he amassed 1100 photos taken before 1949 by 42 photographers, and he found and returned to 420 locations.

    The paired photographs showed "patterns of environmental change and cultural land use that did not agree with the conventional wisdom," he says. "It turns out [the experts] had no data." For example, imagery for the Dry Valleys, a desertlike landscape, indicated that croplands have not expanded as researchers had thought, despite increases in population. The pictures also warn against a current practice of replacing grasslands with forests, as the early photos showed grasslands were the norm and suggested the environment is really better suited to grasslands, Moseley and his colleagues discovered. Both Yin's and Moseley's photos have also revealed nuanced changes to forest cover, rather than a unidirectional trend of forest loss as many had thought.

    Moseley is no longer in China, but others, including the Chinese Academy of Sciences, are following up with similar studies. "I'm passionate about using this technique to inform conservation," Moseley says. "In places like Africa and parts of Asia, where good scientific data do not exist, photographs are a good way to get a quick historical profile."

  13. Tundra in Turmoil

    1. Elizabeth Pennisi

    Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.

    Shrub invasion.

    In just 20 years, shrubs expanded on this meadow (white lines).


    The new norm for the Arctic will not be vast expanses of frozen tundra and bare ground. Instead, warming temperatures have encouraged shrubs to sprout, and some of the first telltale signs of this change came from repeat photography. By 1996, satellite images were detecting more vegetation in the Far North, but it was a 2001 Nature paper that drove home what was happening. Matthew Sturm from the U.S. Army Cold Regions Research and Engineering Laboratory in Fort Wainwright, Alaska, had rescued an impressive series of large-format photographs taken in the 1940s from low-flying aircraft during oil and natural resource surveys. The negatives, 46 centimeters by 23 centimeters, captured the landscape in exquisite detail, down to individual bushes. Sturm set out by helicopter to retake those photographs more than 50 years later. "We didn't know what we would find," recalls Ken Tape, an ecologist at the University of Alaska, Fairbanks, who worked with Sturm.

    They ended up with nearly 300 pairs of photos. To date, they show that in 87% of the scenes, green alder and to a lesser extent dwarf birch and willow have grown bigger, filled in, or moved into previously shrub-free areas. Overall, shrub cover mushroomed by about 38%; only two photos showed a decline. "We can jump back 60 years and we definitely see widespread changes," says Pieter Beck, an ecologist from the Woods Hole Research Center in Falmouth, Massachusetts.

    Isla Myers-Smith of the University of Edinburgh in the United Kingdom was able to leap back even further in her studies of Arctic shrubs. On Herschel Island, located on the Arctic Coast of the Yukon Territory, she and her colleagues found photo albums dating back more than a century chronicling the island's use as a whaling station, police post, and mission. About 50 images showed plots of tundra, five of which she was able to locate again for repeat photographs. All five pairs showed more shrubs, she and her colleagues reported in 2011. More recent comparisons show that shrub expansion is continuing and can be documented over just 20 years.

    Other researchers, meanwhile, have seen similar changes in more than two dozen locales across the Arctic. Now, Myers-Smith, Tape, and Beck belong to a consortium called Shrub Hub that combines repeat photography with vegetation surveys, satellite monitoring, tree ring growth studies, and other work to better understand why shrubs are proliferating in the Arctic. "More shrubs could change carbon stores in the soil, habitat for caribou and other wildlife, and even how the tundra reflects the sun's heat when the shrubs stick up above the snow," further fueling warming, she notes.

  14. Tree Line Shifts

    1. Elizabeth Pennisi

    Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.

    Forest in motion.

    In Sweden, trees moved up a mountain slope, but climate change was not the reason, removal of human impact was.


    Repeat photography is helping reveal when a warmer climate is affecting vegetation—and when it isn't.

    In the American Southwest, work by Robert Webb, a plant ecologist recently retired from the U.S. Geological Survey in Tucson, Arizona, has shown that fewer, shorter freezes are paving the way for more cactus seedlings and certain frost-sensitive shrubs to survive winters. Among Webb's 10,000 paired photographs—some spanning 140 years—are many showing increases in these desert plants.

    In subarctic Sweden, however, some paired photos tell a different story. Modeling predicts that in Sweden's mountainous highlands, milder conditions will enable alpine forests to climb up slopes, as harsh higher altitudes become habitable for seedlings.

    To see if the forest was on the move, Rik Van Bogaert, a biogeographer from Ghent University in Belgium, compared photos of eight mountain scenes taken over a century. Some of the photos were taken around 1910 to document the newly built railroad, others were taken in the 1950s by a master's student studying tree lines, and a few by Van Bogaert himself in 2009.

    About half of the images revealed climbing tree lines. But additional historical documents, as well as tree-ring analyses, indicated that warming conditions are not the main cause. Instead, the trees appear to be gradually reclaiming areas that reindeer herders had used for grazing and camping into the 1920s.

    Such findings have made Van Bogaert a big fan of historical photos. "Not many methodologies," he notes, allow researchers "to study ecosystem changes at a temporal scale of 100 years."

  15. Humans Greening a Landscape

    1. Elizabeth Pennisi

    Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.

    Greening trend.

    A dry Ethiopian landscape has since sprouted more trees, thanks in part to conservation efforts.


    The camera the British army sent to northern Ethiopia in 1868 captured 30 landscape photos that were of interest to Jan Nyssen, a geographer now at Ghent University in Belgium. They've proved unusually valuable, given the scant historical information about vegetation, terrain, and land use in the region.

    All told, Nyssen has now amassed historical photos of Ethiopia from about 20 sources, spanning 1867 to the present. He's been able to create some 500 then-and-now pairs and has been surprised by some of the differences they show. With population increases and climate changes, he and others expected the landscape to become degraded and more desertlike over time. But many sites have more trees and shrubbery now than when the British marched through this mountainous region, he says.

    The trend toward a richer landscape was not consistent, however. The photos suggest an increase in vegetation through the 1930s, then a degrading landscape into the 1970s, with severe desertification between 1975 and 1984. Since then, there appears to have been a gradual improvement as the government and individual landowners have become more conservation and management-oriented. So far, Nyssen says, "most changes are related to direct human intervention and that's overriding climate change." Still, the photos should have "relevance" for studying climate change, he adds, as global warming takes hold.