# News this Week

Science  22 Jan 2010:
Vol. 327, Issue 5964, pp. 398
1. Seismology

1. Richard A. Kerr

To seismologist William McCann, last week's tragic earthquake in Haiti was a horror foreseen. In 1979, he and a colleague had drawn up a global map titled “Seismic Potential of Major Plate Boundaries.” They coded the big fault zones by color—yellows and red denoting the highest probability of rupturing in a big quake. The island of Hispaniola—of which Haiti occupies the western end—was engulfed in red.

“We were concerned because it's been 240 years since the last major earthquake” on the fault that just ruptured, says McCann, who is now an independent consultant with Earth Scientific Consultants in Westminster, Colorado. “Centuries have passed, and this area has been extremely quiet.” With the Caribbean tectonic plate to the south straining against the North American plate on the north, quiet was a bad sign. Stress had to be building, but no big quakes were relieving it. When a section of the plate boundary finally did rupture, it did so with devastating fury.

When the east-west, San Andreas–like fault ruptured, tens of thousands likely perished in what may be the Western Hemisphere's worst disaster in a century. Residents of Port-au-Prince felt “very strong” shaking, according to early estimates by the U.S. Geological Survey. Yet at magnitude 7.0, the quake barely qualified as “major.” So many people and buildings felt such strong shaking because the epicenter was only 16 kilometers from a city of 2 million inhabitants. And the rupture was shallow, extending upward from a depth of about 10 kilometers. Earthquakes like the one that rocked Sumatra in 2004 break tens of kilometers down and are somewhat muffled as a result.

By seismologists' rule of thumb, that shaking meant “moderate potential damage” in Port-au-Prince, but such projections can't take account of local conditions, note seismic engineers. The capital city is built on sediments, not bedrock, McCann says, so the whole valley would shake like a bowl of jelly. Haiti, the poorest country in the Western Hemisphere, “lacks a reasonable building code” to help structures resist shaking, he says, and “has almost no enforcement” of what code it has.

Last week's quake ruptured only a part of the fault segment that broke in 1770 in a quake since estimated at magnitude 7.5, about five times more powerful. For all the damage it caused, “this quake is not really big,” McCann says. Around Hispaniola, “they can get up to magnitude 8,” 32 times more powerful. That's because the island—with the Dominican Republic occupying the eastern two-thirds and Puerto Rico and Cuba nearby—is caught in a tectonic fix. The clash of tectonic plates has been a messy business across Hispaniola. Rather than a single, clean plate boundary running east-west across the island, there are two parallel fault systems that are generating quakes with the “Hispaniola microplate” caught between them.

This doubled plate boundary has produced plenty of quakes, though not many big ones lately. For a 2001 meeting on seismic risk reduction in the Caribbean region, McCann compiled historical, geologic, and seismic records of quakes going back centuries, some dramatic. The magnitude 7.5 in 1770—after which 30,000 people died of sickness and hunger—was something of an aftershock to the century's main event, a magnitude 8.0 in 1751 along the southeastern coast where the Caribbean plate dives beneath the Dominican Republic rather than sliding by as it does in the west. Another magnitude 7.5 broke the central part of the southern fault system a few months later. Then in the 19th century, a magnitude 8.0 hit the north coast of Haiti on the northern fault system. The 20th century was far calmer. In the first half, four magnitude 7s hit the Dominican Republic's north coast, but Haiti was disquietingly devoid of larger quakes throughout.

“The last couple of generations have been lucky,” says McCann, but “we may be coming out of the quiet time we've had.” Stress is always building on a plate-bounding fault, but when that stress is released in a quake, it can transfer stress to its neighbors. That can push them to failing one after another, as seems to have happened in 1751. The faults of Hispaniola may be coming out of their slumber, McCann warns, and it's now only clearer what havoc they can wreak.

2. Global Warming

# Models Foresee More-Intense Hurricanes in the Greenhouse

1. Richard A. Kerr

Fewer but fiercer and more-destructive hurricanes will sweep the Atlantic Basin in the 21st century as climate change continues, a new modeling study by U.S. government researchers suggests. The results, reported on page 454, bear out tentative forecasts from earlier studies, although the researchers caution that this is still far from the last word.

“The models seem to be converging,” says tropical meteorologist James Kossin of the National Climate Data Center's office at the University of Wisconsin, Madison, who was not involved in the work. Plenty of uncertainties remain, Kossin notes, but compared with earlier studies, this one “is more credible; … it's important.”

What makes the new study more realistic is its sharper picture of the atmosphere. In low-resolution models such as global climate models, the fuzzy rendition of the atmosphere can't generate any hurricanes, much less the intense ones that account for most of the damage hurricanes cause. The high-resolution models used by the U.S. National Weather Service to forecast hurricane growth and movement do produce a realistic mix of both weak and strong storms, but those models can't simulate global warming.

So climate modeler Morris Bender of the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey, and his colleagues used a technique sometimes called “double-downscaling.” The group started with the average of atmospheric and oceanic conditions forecast for the end of the century by 18 global climate models. They transferred those averaged conditions into a North Atlantic regional model detailed enough to generate a realistic number of hurricanes, although still too sketchy to get their intensities right. Finally, the team transferred the regional model's storms to an even higher-resolution hurricane forecast model capable of simulating which ones would develop into category 3, 4, and 5 storms.

The first downscaling showed an 18% decline in the total number of hurricanes. In the second downscaling, that decline in the number of storms was limited to moderate-strength storms. Category 4 and 5 storms, with maximum winds of 216 kilometers per hour and above, about doubled in frequency by the end of the century; the strongest storms, with winds of 234 kilometers per hour and above, more than tripled. The results generally matched those of earlier studies that took different approaches to coping with limited resolution. They were also consistent with long-standing theory that as ocean temperatures rise, the additional water vapor driven into the atmosphere can both intensify existing storms and inhibit the formation of new storms.

The group calculates that although the overall number of hurricanes would decline in a warmer world, they would still cause more damage, according to the modeling. Category 3 to 5 hurricanes have accounted for 86% of all U.S. damage despite constituting only 24% of U.S. landfalls, the group notes. That's because when storms move up from one category to the next, the potential damage roughly doubles. The group finds that in the models, the increase in the rare, most intense storms dominates, leading to a net increase in potential damage of roughly 30%.

The researchers note that the new modeling offers no support for claims that global warming has already noticeably affected hurricane activity. In the real world, the number of Atlantic hurricanes observed during the past 25 years has doubled; in the model, global warming would cause a slight decline in the number over the same period. Given that the mid-resolution model used by the group duplicates the observed rising trend, it may be natural. And the group estimates—very roughly—that so far any effect greenhouse warming has had on hurricane intensity should still be unrecognizable amid natural variations in hurricane activity.

“It's a good step, a big step forward,” says tropical meteorologist Peter Webster. “They've done about as much as you can do with downscaling, [but] it's not the final step.” As ever, researchers are looking for yet more computer power and higher resolution to boost the realism of simulations. If the models continue to converge as realism increases, the monster storms that seemed to be already upon us would be removed to decades hence.

3. Scientific Cooperation

# African Physicists Set Their Sights on Mammoth Scope

1. John Bohannon

DAKAR—At times, it has looked more like a scene from the movie Braveheart than a science conference. “Together we are stronger!” intoned Charles McGruder III to a room packed with physicists from across Africa, who applauded and pumped their fists in the air. McGruder, an astronomer from Western Kentucky University in Bowling Green and a past president of the U.S. National Society of Black Physicists (NSBP), was calling on the scientists here to show a united front in Africa's bid to host what would be the world's largest scientific instrument, the Square Kilometre Array (SKA) radio telescope. Last week's meeting* in the Senegalese capital not only was the first physics conference spanning the continent but also became a rally for African science, including the establishment of a new African Physical Society.

On the minds of many here was SKA, a next-generation radio telescope that will probe gas clouds in the early universe with a collecting area 100 times that of the Very Large Array in Socorro, New Mexico. A lengthy site-selection process has already eliminated China and South America, leaving just Africa and Australia (Science, 29 September 2006, p. 1871), with a final decision by the 19 SKA member states due in 2012. “Five years ago, everyone assumed that Australia was sure to get the SKA,” says Phil Charles, director of the Southern African Large Telescope (SALT), an 11-meter optical instrument in Sutherland, South Africa. Australia has long been “a giant” of radio astronomy, he says, whereas Africa had almost no radio telescopes.

But then in 2006, the government of South Africa committed $250 million to constructing an array of radio dishes as a precursor to the African SKA. Seven of the planned 80 dishes of the array—known as MeerKAT—have now been built. “Now people are taking our bid seriously,” Charles says. Meanwhile, Australia is building up its own seed array of dishes, called ASKAP. The African bid faces unique political challenges. Whereas Australia would host the entire telescope within its own borders, in Africa the massive array of dishes would be spread across nine countries, with the core in South Africa. Coordinating its construction, use, and maintenance across those borders would require unprecedented regional scientific cooperation. Civil wars and border disputes are serious hurdles. “I put the chances at 50–50” for the African bid, says physicist Cingo Ndumiso, manager of South Africa's National Laser Centre. “The biggest problem is putting the legal framework in place in each state” so that information and researchers can move freely. But the benefits of building SKA in Africa far outweigh the difficulties, argues McGruder: “Just the construction alone of the SKA will improve Internet access and help Africa enter the knowledge economy.” McGruder hopes that such arguments will help African researchers persuade their governments to work together to win the SKA bid. The scientists at the meeting took a first step by founding the African Physical Society. An African Astronomical Society is now in the works. Having pan-African scientific organizations will be “crucial” for reducing governmental red tape, says the conference organizer, Ahmadou Wagué, a physicist at the University of Dakar. “Mobility is a huge problem. This has been the first time that many of us scientists have met each other face to face” due to visa difficulties. McGruder adds that having pan-African science groups will also help with finances. “Funding from outside for African science currently goes through the African Union,” he says. “Scientists need to have control of that money.” In spite of the good will at the meeting, there was no consensus on the African bid's chances of success, nor even of SKA's benefits. “I worry that it would worsen the problem of brain drain from the other African countries to South Africa,” says a European physicist at the meeting, who did not want to be identified because of his collaborations in Africa. Others dismissed such worries. “This meeting makes it clear that Africa has achieved the critical mass of scientists,” says Sune Svanberg, a physicist at Lund University in Sweden. “The SKA belongs here.” Between now and 2012, the lobbying will be intense. The total construction cost for SKA is estimated at more than$2 billion, says McGruder, and the United States may provide one-third of that. Because of this, McGruder's influence could be pivotal, says SALT's Charles. Where SKA ends up will be largely determined by “the people with the deepest pockets,” he says. McGruder adds that “bringing the SKA to Africa is [the] top priority” of NSBP. “We have a real kinship.”

The ultimate lobbying moment could come this summer when South Africa hosts the World Cup football tournament. “If Obama comes for a visit, we're going to take him to SALT and MeerKAT,” says Charles with a twinkle in his eye. “We want him to see cutting-edge African astronomy for himself.”

• * The LAM International Workshop on Optics and Lasers in Science and Technology, Dakar, 11–16 January 2010.

4. Iran

# Killing of Professor Sparks Fight Over His Science and His Politics

1. Yudhijit Bhattacharjee

As the first Iranian to receive a physics Ph.D. from a domestic university, Masoud Alimohammadi was a source of pride to his country. In 1989, when Pakistani Nobelist Abdus Salam inaugurated the doctoral program at the Sharif University of Technology, Alimohammadi's mentors touted him as proof that Iran could now produce the next Salam. In 2008, the government picked Alimohammadi, by then a professor of theoretical physics at the University of Tehran, to be its representative for an international scientific facility being built in Jordan called SESAME, Synchrotron-light for Experimental Science and Applications in the Middle East.

Last week, Alimohammadi was assassinated by a remote-controlled motorcycle bomb outside of his apartment. And the country's guardians clutched him even tighter to their bosom. Iranian authorities characterized the killing as an attempt by U.S. and Israeli intelligence agencies to rein in Iran's nuclear program. But colleagues and others believe that the government may actually be the culprit. They point to recent actions by Alimohammadi both before and after the controversial reelection of President Mahmoud Ahmadinejad last June as evidence that the physicist favored political changes and that his death was a warning to other academics who supported the reform movement.

One thing is clear: Alimohammadi was not a nuclear scientist. Trained as a theoretical particle physicist, he had spent years studying string theory and, more recently, dark energy. “His scientific contributions to the Iranian physics community cannot be replaced in the foreseeable future,” says Hessamaddin Arfaei, a physicist at Sharif University who was Alimohammadi's thesis adviser.

Alimohammadi was one of 240 Tehran professors who had declared their support for Ahmadinejad's main opponent, Mir-Hossein Mousavi. A more recent example of his activism—and something that reformers say made him a target—occurred just a week before he was killed.

According to Ali Nayeri, an Iranian-born physicist at Chapman University in Orange, California, who first met him at Sharif University, Alimohammadi criticized the regime and urged open dialogue at a 5 January forum held at his department. Speaking to a gathering of students, he said he knew that fear of reprisals kept many more on campus from attending the event. “I too was instructed not to come,” he said, according to Nayeri, who translated the talk—posted on YouTube—for Science. Frequently interrupted by audience members, some of whom wanted to hear him talk about fraud in the presidential election, Alimohammadi urged students to press on with the reform movement without descending into chaos.

Nayeri, a sympathizer of the reformist movement, says he and many students he has talked to believe that Alimohammadi paid a price for his activism. “His killing was masterminded by the Islamic Republic,” Nayeri alleges. “The message to academics is, ‘Don't meddle in the political sphere.’”

But another former colleague from the Institute for Studies in Theoretical Physics and Mathematics—where Alimohammadi was a research fellow in the early 1990s—says it's not implausible that the killing was planned by a foreign power. Reza Mansouri, who was deputy minister for research under Ahmadinejad's predecessor, Mohammad Khatami, says the disappearance last year of an Iranian nuclear scientist, Shahram Amiri, during a pilgrimage to Saudi Arabia has reinforced rumors that some foreign intelligence agencies would like to see some Iranian physicists dead. Maybe Alimohammadi was “targeted based on a wrong interpretation of his expertise,” he says.

Last week's state funeral featured a confrontation between reformers and government supporters, with each side claiming the allegiance of the slain physicist. Meanwhile, more than 100 academics of Iranian origin around the world have demanded that the Iranian government investigate the murder and bring the assassins to justice.

5. ScienceNOW.org

# From Science's Online Daily News Site

Time Machine Tune Up It took nearly 30 years and a lot of heated debate, but a team of researchers has finally produced what archaeologists, geologists, and other scientists have long been waiting for: a calibration curve that allows radiocarbon dating to achieve its full potential. The new curve, which now extends back 50,000 years, could help researchers work out key questions in human evolution, such as the effect of climate change on human adaptation and migrations.

A Better Suspension Bridge A bit of bridge-building wisdom that dates back to 17th century Dutch polymath Christiaan Huygens needs a rethink, reports a team of structural engineers. Following Huygens's lead, engineers have assumed that the best design for a suspension bridge relies on simple cables that hang between towers in an elegant curve. A more-complicated design uses less material and is therefore more efficient, according to the new work. But it's not likely to appear on roads.

Why Did Fish Evolve Gills? If you said, “to breathe,” then you probably passed Biology 101. But you—and the textbooks—may not be right. A new study argues that the structures really emerged to help keep fish in chemical balance with their environment.

Oil Drop Navigates Complex Maze Lab rats, watch your back. Scientists have found a way to make simple droplets of oil navigate complex labyrinths with the same skill as laboratory rodents. The advance could help researchers devise better ways to solve other mazelike problems, from rooting out cancer in the body to mapping paths through traffic jams.

# Google Plots Exit Strategy As China Shores Up 'Great Firewall'

1. Richard Stone,
2. Hao Xin

BEIJING—Google's declaration last week that it will no longer play ball with Chinese censors has inflamed tensions between backers of the free flow of information and advocates of China's increasingly assertive efforts to cleanse the Internet of offensive material.

Much more is at stake than the possible demise of a single Web site, Google.cn. “Any effort to block open access to the Internet would hurt the Chinese academic community and the long-term interests of China,” says Rao Yi, life sciences dean at Peking University. In recent weeks, however, China has slapped new controls on Web content and commerce. For example, last month the Ministry of Industry and Information Technology (MIIT) issued rules intended to “weed out pornography” on Web sites that provide content to cell-phone users. And authorities have imposed an Internet blockade on an entire region of western China, where people now can access only a few sites within China.

It's unclear whether Google's defiance will affect scientists. If the government were to retaliate by adding Google.com to its roster of forbidden sites, access could be cut off to Gmail and two research tools, Google Scholar and Google Earth. It wouldn't be a total loss: PubMed, for instance, could compensate in part for the loss of Scholar. And some see the upheaval as a blessing in disguise. In the long term, argues Zhu Yong-Guan, director of the Institute of Urban Environment in Xiamen, “Google's pullout will in a way stimulate China's own innovation.”

Google's operations in China were fraught from the start. When the company launched Google.cn in January 2006, it took flak for agreeing to censor search results, as Microsoft's MSN and other sites do. In that sense, Google was merely obeying the law. A State Council decree in 2000 bans Web content that—among other things—harms security, subverts state power, destroys national unity, incites ethnic hatred, disturbs social order, or spreads obscenity.

Google's relations with authorities soured last summer, after government-run CCTV accused Google.cn of suggesting obscene associations when search terms like “mother” and “son” were entered. The government shuttered the Web site temporarily. Then last month, Google uncovered a “highly sophisticated” attack targeting Gmail accounts of human-rights activists, according to Senior Vice President David Drummond in a 12 January post to Google's official blog. In response, he wrote, “We have decided we are no longer willing to continue censoring our results on Google.cn.” Google was expected to meet with Chinese officials this week to, as Drummond says, discuss “the basis on which we could operate an unfiltered search engine within the law, if at all.”

Of paramount importance to scientists here is not Google.cn's fate but whether access to information in China will be further restricted. Apparently realizing that innovation requires freedom to explore new ideas, censors are not deaf to pleas from the academic community. When researchers recently complained about some pages of the Massachusetts Institute of Technology's Web site being blocked, according to an official with the China Education and Research Network, a national academic network under the education ministry, access was restored.

But last July's riots in Xinjiang Uyghur Autonomous Region strengthened the hand of Chinese officials who favor tighter Internet curbs. After claiming that social networking sites were used to orchestrate the violence, authorities cut off the region's Internet access, complicating scholars' lives (Science, 11 December 2009, p. 1471). Late last month, access was restored to many local sites, but so far only four outside Xinjiang. Elsewhere in mainland China, Internet access is much freer—although Facebook, YouTube, and major blog sites are blocked.

Across China, more restrictions are coming on line to cope with the skyrocketing number of people who use cell phones to access the Net: 60.8% of the country's 384 million Internet users. Ostensibly to fight the spread of porn, MIIT and other organs are working to better monitor content originating from cell phones and to “speed up pilot projects for discovering harmful information” on wireless Internet, according to MIIT's Web site. As the ministry tightened up, Google abruptly postponed this week's planned release of its new mobile phone technology in China, offering no information on whether the launch would be rescheduled.

In an interview posted to the State Council's Web site last week, the council's information director, Wang Chen, stated that “China's Internet is entering an important stage of development, confronting both rare opportunities and severe challenges.” That's one sentiment both proponents and critics of the Great Firewall can agree on.

7. Germany

# Under Fire From Pharma, Institute May Lose Its Director

1. Gretchen Vogel

A long-running feud between pharmaceutical companies and the German institute that evaluates the effectiveness of medical treatments could cost the institute director his job. Although the post is supposed to be apolitical, members of Germany's new coalition government have called for Peter Sawicki, founding director of the Institute for Quality and Efficiency in Health Care (known by its German acronym IQWiG), to be replaced with someone who is friendlier to the pharmaceutical industry. As Science went to press, the institute's board of directors was expected to decide on 20 January whether Sawicki, a clinical researcher and diabetes expert, will be replaced when his contract runs out later this year.

Sawicki's supporters say the move would endanger the institute's reputation for impartial and rigorous science, and earlier this month a petition signed by 600 doctors and clinical researchers called on the health minister and the board to keep Sawicki on. Gerd Antes, director of the German Cochrane Centre in Freiburg, a not-for-profit organization that analyzes health care effects, says that replacing Sawicki would significantly undermine IQWiG and its work. Antes views the anti-Sawicki push as “part of the political game to soften and to weaken rigorous procedures for new drugs and medical devices in Germany.”

IQWiG, based in Cologne, was started in 2004 as part of a reform of the German health care system. With a function similar to the U.K.'s National Institute for Health and Clinical Excellence (NICE), IQWiG's reports inform the panel that decides which treatments are covered by Germany's publicly funded insurance plans. Sawicki has tussled with drug companies over access to their unpublished studies and over reports from the institute, such as the one that found “no evidence” that a new product was superior to older synthetic human insulin. Industry groups, especially the German organization of research-based pharmaceutical companies, VFA, have been highly critical of IQWiG, saying, for example, that IQWiG is too selective in deciding which studies to include in its evaluations.

Big pharma's attacks have even come from outside Germany. In March 2009, the Pharmaceutical Research and Manufacturers of America petitioned the Obama Administration to put Germany on a trade and intellectual property “priority watch list” chiefly because of IQWiG's influence on the German drug market. The petition complained that the institute has “inadequately taken into account the value of innovative pharmaceuticals,” among other complaints. The Obama Administration declined to put Germany on its watch list.

Sawicki acknowledges that it is difficult for new drugs or techniques to make the grade. “We have introduced a method based on patient-relevant outcomes: morbidity, mortality, and quality of life,” he says, while avoiding what he calls “invalid surrogates,” such as cholesterol levels or bone density. “You can lower cholesterol and increase mortality. You can lower blood pressure and increase heart failure,” he says. Second, he says, “we are looking for progress” rather than just effectiveness, which means that an innovation is not compared with a placebo but with the current standard of care. “We are trying to answer the question, ‘Is it better?’” Sawicki says he has some sympathy for the drugmakers: “It is very difficult to produce something better than what we already had.”

Industry complaints about the institute have found some support among German politicians. In the October agreement forming Germany's new governing coalition, the parties stated their intention to examine IQWiG's methods, with the goal of “increasing the acceptance of the institute's findings among patients, caregivers, and producers.” In late November, German media reported that recommendations circulated among top health policymakers called for Sawicki to be replaced and for the institute to be made more industry-friendly. Sawicki is also facing an ethics inquiry, which he says he requested after a new finance director found irregularities in expense accounts. Specifics of the inquiry, involving a leased Audi as an official car and business-class domestic flights, leaked earlier this week.

The institute's work is bound to be controversial, says Antes. Similar research in the United States has also attracted criticism (Science, 27 November 2009, p. 1183). Although Sawicki's term hasn't been flawless, Antes says, he has been instrumental in getting the institute up and running. “He never gives in. He has a very strong spine. In 5 years, they have established an institute with a good international reputation.”

8. ScienceInsider

# From the Science Policy Blog

The World Health Organization (WHO) is defending itself from Wolfgang Wodarg, a German physician who has called the H1N1 swine flu pandemic “fake” because the virus isn't very different from existing strains. WHO has dismissed Wodarg's suggestion that big pharma coaxed WHO into declaring a pandemic so that it could produce and sell more vaccine.

Scientists at the helm of the Intergovernmental Panel on Climate Change are discussing steps to respond to issues raised by e-mails uncovered at the University of East Anglia after a theft by a presumed hacker in November. IPCC says none of the e-mails suggest malfeasance, but it is nonetheless considering outside reviews and training for authors to deal better with outside pressures.

French science minister Valérie Pécresse has chosen Alain Fuchs, now head of Chimie ParisTech, to lead the National Centre for Scientific Research, a €3.4 billion agency whose 12,000 scientists study everything from archaeology to astronomy.

A 150-page report on minority faculty at the Massachusetts Institute of Technology tiptoes around the question of racism in trying to understand the low numbers of underrepresented minorities—2.7% of MIT's science faculty and only 3.4% of the hires in the past 20 years. Its recommendations, embraced by senior administrators pledging to do better, include improved mentoring, training in hidden biases, and cluster hires as well as closer monitoring of current practices.

A diverse group of scientific publishers, librarians, and university officials think that all U.S. research agencies should require their grantees to make their papers freely available as soon as possible, in line with the policy of the National Institutes of Health.

For the full postings and more, go to blogs.sciencemag.org/scienceinsider.

9. Archaeology

# The Tangled Roots of Agriculture

1. Michael Balter

A once-popular view that climate change led the Near East's ancient Natufians to begin domesticating plants and animals is under increasing attack, but alternative paradigms are still being formed.

PARIS—About 20,000 years ago, when the last ice age was at its peak, sparse populations of hunter-gatherers roamed the largely treeless steppes of the eastern Mediterranean region in highly mobile bands of perhaps 15 to 50 people. For thousands of years, they eked out a marginal existence, traveling widely to gather tubers and nuts and hunt deer and gazelles. Then, about 14,500 years ago, the climate warmed suddenly. Woodlands of pistachio, olive, and oak, along with lush fields of wild wheat and barley, began to take over the steppes. Just as suddenly, hunter-gatherers in what is now Israel, Jordan, Syria, and Lebanon began doing things they had rarely, if ever, done before. Although they continued to hunt, they built permanent houses of stone and wood, and buried their dead in and around them with elaborate rituals. They ground up wild cereals with mortars and pestles, made tools and art objects from animal bones, and perhaps even practiced Shamanism. And they gathered in sedentary or semisedentary communities of up to several hundred people.

These were the Natufians, a culture so different from what came before that archaeologists once thought they were invaders from afar. Their large, socially complex communities “represent a key development in human settlement history,” says archaeologist Phillip Edwards of La Trobe University in Victoria, Australia. In the Near East, Natufian culture was the next-to-last stop on the long road to farming, and many of its features seem to foreshadow the Neolithic epoch, when the earliest farmers built densely populated villages of stone and mud brick, painted their walls with art, and buried their dead under the floors. “Many of the activities present in the early Neolithic had their roots in the Natufian,” says zooarchaeologist Natalie Munro of the University of Connecticut, Storrs.

But the warmth that ushered in the Natufian era didn't last long. About 13,000 years ago, smack in the middle of the Natufian cultural florescence, a sharp, 1300-year-long cold and dry spell called the Younger Dryas reversed the post–ice age warming. For some archaeologists, the Natufian response to this sudden cooling holds the clues to one of archaeology's central mysteries: why former hunter-gatherers settled down and invented agriculture. According to a once-popular hypothesis, the Younger Dryas created an environmental crisis that forced the Natufians or whoever replaced them to begin domesticating plants and animals to ensure that they had enough to eat (Science, 20 November 1998, p. 1446), thus spurring the world's first experiments with agriculture.

Back in 1989, when archaeologists Ofer Bar-Yosef of Harvard University and François Valla of the University of Paris in Nanterre convened the world's leading Natufian experts for a meeting, the Younger Dryas model was well on its way to becoming a leading paradigm for agricultural origins. But when Bar-Yosef and Valla called the Natufian mavens back together for a meeting in Paris last fall,* opinions had shifted. In talks and recent journal articles, many researchers rejected the idea that the Younger Dryas forced Near Eastern hunter-gatherers to become farmers—or that the Natufians themselves were precocious farmers, as some had suggested.

“Agriculture was not driven by climate change,” says Lisa Maher, an archaeologist at the University of Cambridge in the United Kingdom. Nor, says Arlene Rosen, a geoarchaeologist at University College London (UCL), was Natufian culture simply a way station on the road to farming: “The Natufians were not on a trajectory to agriculture. In fact, they carried on … for 1300 years as successful foragers during the Younger Dryas.” Nevertheless, researchers say, the Natufians' successful adaptations to what nature threw at them, and their many cultural innovations, may have helped make agriculture possible when the weather was more conducive to it.

The Natufians were discovered and named in 1928 by the legendary British archaeologist Dorothy Garrod. At Shuqba Cave northeast of Jerusalem and at el-Wad Cave on Mount Carmel, Garrod unearthed distinctive, crescent-shaped flint tools called lunates, as well as grinding stones and mortars, figurines and jewelry, the remains of stone buildings, and burials of dozens of individuals.

Today, about 60 Natufian sites are known, ranging from larger, villagelike “base camps” to smaller “mobile camps.” Archaeologists divide the culture—often identified by the presence of the lunates, probably used as arrowheads and for cutting plants—into two periods: a more sedentary Early Natufian, characterized by larger encampments and elaborate group burials adorned with ochre and jewelry; and a more mobile Late Natufian, with smaller camps and undecorated, individual burials.

Archaeologists agree that the milder, post–ice age climate conditions helped transform mobile hunter-gatherers into the more sedentary Natufians. In the early years of Natufian research, archaeologists had only a rough idea how old their sites were, in part because of the lack of a suitable radiocarbon calibration curve (Science, 15 September 2006, p. 1560). But new dating shows that the Natufians appeared right around the time of the Bølling-Allerød interstadial warm period, which began 14,500 years ago and lasted until the beginning of the Younger Dryas. “There is clearly a striking correlation between the emergence of the larger-scale Natufian settlements and the beginning of the warm and moist Bølling-Allerød,” says UCL archaeologist Andrew Garrard. During colder times, this region was mostly a treeless steppe dotted with shrubs and grasslands, and new forests expanded rapidly, presumably providing the Natufians with nuts and other calorie-rich plant resources and encouraging them to settle down.

Nevertheless, researchers have had little evidence on Natufian use of plants, which preserve poorly in the Mediterranean's wet winters and hot, dry summers. “We have had almost no direct data on plant use in this period,” says Garrard.

New research at Dederiyeh Cave in northwest Syria is helping to fill that gap. In unpublished work presented here, archaeologist Yoshihiro Nishiaki of the University of Tokyo reported the remains of stone buildings occupied between 14,000 and 13,000 years ago, one of which was heavily burnt, charring and preserving many plant remains. So far, archaeobotanist Ken-ichi Tanno of Japan's Research Institute for Humanity and Nature in Kyoto has found that nearly 90% of the 12,000 plant fragments he studied come from pistachio and almond trees. Tanno also found significant amounts of wild wheat, one of the main cereals domesticated in the region during the later Neolithic period. The finds at Dederiyeh show that Natufian plant use was “intensive, knowledgeable, and complex,” says Maher. But there's no sign that the Natufians actually cultivated plants at Dederiyeh rather than simply collecting them wild.

There is also plentiful evidence of Natufian hunting, particularly of the mountain gazelle. Just outside el-Wad Cave, for example, where archaeologist Mina Weinstein-Evron of the University of Haifa in Israel has led renewed excavations since the mid-1990s, Haifa zooarchaeologist Guy Bar-Oz found that gazelle made up about 75% of the animal bones. Moreover, some researchers say that the pattern of gazelle hunting argues against the idea that a harsh climate during the Younger Dryas caused Natufian population levels to crash. The intensity of gazelle hunting continued unabated during the Younger Dryas, according to studies by Bar-Oz, Munro, and others, a finding they say is inconsistent with decreases in the Natufian population.

The Younger Dryas, named for the sudden return to more southern latitudes of the cold-adapted plant Dryas octopetala, has been precisely dated from isotopic ratios of oxygen, nitrogen, and other elements in the Greenland ice cores, which vary with changes in temperature and moisture. These records indicate that the Younger Dryas stretched from 12,900 to 11,600 years ago; pollen cores and other proxy climate indicators suggest that at least parts of the Near East also experienced this cold, dry spell. The Younger Dryas dates correspond closely to the calibrated dates for the Late Natufian, thought to have begun about 13,000 years ago. This period, archaeologists agree, is marked by at least a partial return to the more mobile lifestyle that preceded the sedentary Early Natufian. Beginning in the late 1980s, Bar-Yosef, Anna Belfer-Cohen of The Hebrew University of Jerusalem, and other researchers argued influentially that the Late Natufian culture was a response to the cold, dry conditions, which shrank the resource-rich forests and made wild cereals such as wheat and barley more scarce. They argued that the region's hunter-gatherers turned to agriculture, planting and cultivating fields of the now-precious grains, in a hypothesis often repeated in journal articles and popular books, not to mention on Wikipedia.

The strongest evidence for this idea comes from the site of Abu Hureyra in Syria, excavated during the 1970s by a team led by archaeologist Andrew Moore, now at the Rochester Institute of Technology in New York state. They found plump rye seeds, which suggested to them that humans had selected over time for large grains. Based on this and other lines of evidence, Moore and UCL archaeobotanist Gordon Hillman argued that rye and perhaps other cereals were domesticated at Abu Hureyra about 13,000 years ago, roughly at the beginning of the Younger Dryas. If true, that would make it the earliest evidence of farming in the world. Supporting evidence came from indications that the Late Natufians intensified their processing of plants. For example, a 2004 study of three Natufian sites in Israel by archaeologist Laure Dubreuil of Trent University in Peterborough, Canada, found more grinding stones in the Late than Early Natufian, as well as evidence from use wear that the stones were increasingly used to grind cereals and legumes. However, the grinding stones could also have been used for working animal hides and grinding ochre for ritual burials, according to a follow-up study published in Antiquity late last year by Dubreuil and archaeologist Leore Grosman of Hebrew University.

Despite the Younger Dryas's 20-year run as a leading explanation for the rise of agriculture, many scientists remained skeptical, and the idea has come under increasing attack. “The so-called impact of the Younger Dryas was always a matter of belief, not a matter of science,” says Valla. Archaeobotanist George Willcox of the Archéorient research center in Jalès, France, says that “there is only one site where [the younger Dryas explanation] could possibly work, and that's not enough.” That site is Abu Hureyra, but Willcox isn't convinced that the nine fat rye seeds reported there really represent domesticated grain. “There are so few of them,” he says, adding that “the general consensus is that plump grains are not good evidence for domestication.”

Other archaeologists see little evidence that the Late Natufians actually faced an environmental crisis. Archaeologist Nicholas Conard of the University of Tübingen in Germany and his co-workers have found considerable evidence at Baaz rock shelter in Syria that Natufians ate freshwater fish, which points “to the presence of stable sources of flowing water at a time when we are supposed to be in an environmental crisis due to aridity.”

And newer calibrated radiocarbon dating suggests that the Natufians did reasonably well during the entire Younger Dryas, Grosman argued in a talk here. The calibrated dates now stretch the Natufian period from about 2300 uncalibrated years to well over 3000 calibrated years and make the Late Natufian even longer than the Early Natufian. To have survived the return to harsh conditions for so long, Rosen says, the Late Natufians must have had a “stable adaptation” to the Younger Dryas. Moreover, Munro says, the increased mobility of the Late Natufian was not a likely “trigger for agriculture” and may have in fact postponed it.

Some Younger Dryas advocates are not convinced by this logic. Bar-Yosef argues that many of the first Neolithic sites, which cropped up just as both the Late Natufian and the Younger Dryas ended about 11,500 years ago, are “more than 10 times as large as the biggest Natufian sites. Where did they come from if food supplies were not improving during the late centuries of the Younger Dryas?” And Moore says that although the Younger Dryas was not the only catalyst for farming, at Abu Hureyra it “provided a key trigger.” As evidence he cites not only the rye grains but also other signs, such as a rise in weeds typically found in cultivated fields and an increase in legumes such as lentils, which Moore says could not have survived the dry Younger Dryas unless they were deliberately cultivated. Moore also points to increasing evidence that early farmers engaged in “predomestication cultivation” long before cereals and other plants took on the domesticated morphology that makes them recognizable to archaeobotanists (Science, 29 June 2007, p. 1830).

But if the dissenters are right and the Younger Dryas did not trigger the rise of agriculture in the Levant, what did? Many archaeologists have concluded that farming began not during the cold, dry climate that hit Natufian culture at its height, but only later—after warm, moist conditions were restored 11,600 years ago. In this view, says Rosen, prehistoric peoples were both “pushed” into agriculture by growing populations that fostered renewed sedentism and “pulled” by the increased rainfall and milder climates that made farming more attractive and less risky. Only then, Rosen says, was nature in full “come-hither mode,” making agriculture not only possible but also desirable.

Willcox, whose own research suggests that both cultivation and domestication didn't start until the Holocene, says he “agrees 100%” with this viewpoint. But although the Natufians may not have invented agriculture, many archaeologists say, their many cultural innovations—in art, technology, architecture, and possibly experimentation with wild plant cultivation—probably made later developments possible. In a sense, says anthropologist Donald Henry of the University of Tulsa in Oklahoma, the Natufians were “preadapted” for farming—even if, as Valla puts it, “they had no clue what was to follow.”

• * The Natufian Culture in the Levant II, Paris, 7–11 September 2009.

10. Science Indicators

# Trends Document China's Prowess

1. Jeffrey Mervis

A new report shows how a decade of investment in science and technology has moved the world's most populous nation into the front ranks on key global indicators.

China has arrived. But the rest of the world has not left the building. That's the message from the 2010 edition of Science and Engineering Indicators, the newly released biennial collection of data on the global scientific enterprise from the U.S. National Science Foundation (www.nsf.gov/nsb/sei).

“I don't think we've ever seen another country in which S&T spending has risen by 20% annually for more than a decade,” explains NSF's Rolf Lehming, who oversees the statistical compendium. “The results show up everywhere: percent of GDP devoted to research, undergraduate degrees, the value of knowledge-intensive products.” The 2010 volume reflects “a consolidation” of what's been taking place for years, he adds, “and we don't see a flattening of these trends.”

Yet China's rise doesn't mean that other countries aren't also continuing to invest in research and education. Here is a sampling of global metrics featured in this year's Indicators—which fails to capture the international economic crisis of 2008–09—plus a snapshot of the current job market for U.S. scientists.

11. FALL MEETING OF THE AMERICAN GEOPHYSICAL UNION, 14–18 DECEMBER 2009, SAN FRANCISCO, CALIFORNIA

# Flows on Mars But No Water

1. Richard A. Kerr

Researchers operating the next-generation camera orbiting Mars have found eight more of the steep gullies where it looks as if water recently gushed downhill. But the timing and geographic distribution of the flows point not to liquid water but to bone-dry flows of debris somehow facilitated by a ground frosting of frozen carbon dioxide, they announced at the fall meeting of the American Geophysical Union.

Finding liquid water on Mars would open the possibility of present-day life on the frigid, forbidding planet. So when planetary scientists reported in 2006 that they had photographic evidence that liquid water had flowed on the martian surface twice in recent years, astrobiologists in particular took notice (Science, 8 December 2006, p. 1528).

Now researchers operating the next-generation camera orbiting Mars have found eight more of the steep gullies where it looks as if water recently gushed downhill. But the timing and geographic distribution of the flows point not to liquid water but to bone-dry flows of debris somehow facilitated by a ground frosting of frozen carbon dioxide. “I think they have a very compelling case that [the flows] are carbon dioxide–related,” says planetary scientist Oded Aharonson of the California Institute of Technology in Pasadena. The next question is whether the same dry process could have actually created the gullies.

The dry explanation came in back-to-back talks at the meeting by planetary scientists Serina Diniega and Colin Dundas—both of the University of Arizona, Tucson—with their UA colleagues Alfred McEwen and Shane Byrne. Looking at images taken from orbit during the past 9 years (4.5 martian years), including those from the HiRISE camera on board Mars Reconnaissance Orbiter, they searched for discernible changes from one imaging pass to the next.

Diniega and her colleagues focused on gullies cut into sand dunes. The selected gullies have a classic form: an upper alcove eaten into the dune, a narrow channel cut by sand draining from the alcove, and an apron of sand deposited at the channel's lower end. They found 17 gullies where changes had occurred: Aprons had grown, channels had widened, or whole new channels had formed. These active dune gullies were located between 45°S and 52°S, where it gets cold enough for part of the carbon dioxide atmosphere to freeze and form centimeters-thick frost layers on the ground. All 17 of the changes appeared to happen during the early southern spring, when any frost would be thickest and temperatures were just beginning to rise.

That combination of particularly frigid latitudes and springtime warming suggests that carbon dioxide frost was essential to the recent flows, Diniega said. Perhaps the weight of the frost triggers small avalanches, she said. Then the frost might turn into gas that makes sand into a free-flowing fluid, transforming a tiny avalanche into a big, erosive one.

Dundas and his colleagues concentrated on classically shaped gullies on crater walls. They found eight new examples of changes—a lighter or darker tone to gully deposits or changes in gully shape. The eight cases out of 10 known whose timing could be constrained tended to occur in winter and never in summer, Dundas said, consistent with the timing of dune gully changes. And the crater gully changes were not always superficial; in one case (see figure), meter-scale boulders appear to have been moved.

“What impressed the heck out of me was the boulders moving down the slope,” says applied physicist Michael Hecht of the Jet Propulsion Laboratory in Pasadena. “There's a significant amount of material being moved.” Aharonson sees a role for carbon dioxide frost in triggering flows down both dune and crater gullies, at least the higher-latitude ones reported here. And frost is “a good candidate” for creating dune gullies in the first place, he says. Forming crater-wall gullies is another matter. Flowing liquid water—perhaps in an earlier, warmer era—is still in the running for that more demanding chore.

12. FALL MEETING OF THE AMERICAN GEOPHYSICAL UNION, 14–18 DECEMBER 2009, SAN FRANCISCO, CALIFORNIA

# Magnetics Point to Magma 'Ocean' at Io

1. Richard A. Kerr

Space physicists presented evidence at the fall meeting of the American Geophysical Union for a global ocean tens of kilometers beneath the volcano-pocked surface of Io. This one, however, would be mostly molten rock.

Three of Jupiter's large moons have global salty oceans under kilometers of ice, but the fourth, Io, is just a ball of rock. Nevertheless, space physicist Krishan Khurana of the University of California, Los Angeles, and colleagues presented evidence at the meeting for a global ocean tens of kilometers beneath the volcano-pocked surface of Io. This one, however, would be mostly molten rock, harkening back to the solar system's very earliest days when most big, rocky bodies sported a magma ocean.

Planetary geologist Alfred McEwen of the University of Arizona, Tucson, says the new findings “definitely support the idea of significant [magma] in Io's mantle” and possibly a full-blown magma ocean. At a minimum, much of Io's rocky innards is likely more molten mush than solid rock.

Planetary scientists have long wanted to probe Io's interior for a magma ocean. In 1979, theorists predicted a fiery surface on Io and a magma ocean within it. Jupiter's gravity raises tides in Io, they noted, kneading the solid rock of the moon and generating heat in the interior. Spacecraft immediately found more volcanic activity on Io than in the rest of the solar system combined. And planetary geologists eventually found at least a few of Io's 100 known volcanic hot spots to be hundreds of degrees hotter than the hottest lavas on Earth, suggesting a crystal-laden “mushy magma ocean” (Science, 3 December 1999, p. 1827).

But when space physicists tried to probe Io's interior, they encountered an engulfing cloud of confounding debris. In the case of the other three satellites, Jupiter's powerful magnetic field sweeps through the salty ocean and induces an electrical current. That current generates a moon-centered magnetic field that spacecraft flying by could detect. Molten rock would work similarly, but Io's high-flying volcanic debris becomes electrically charged and would tend to mask any weak magnetic field induced in a magma ocean.

But in the course of preparing a proposal to return to Io, Khurana and colleagues went back to magnetic-field data gathered near Io by the Galileo spacecraft. They removed the masking interference as best as they could, leaving what appeared to be an induced field recorded during one flyby. To prove that their first try wasn't a fluke, they corrected magnetic data from a second flyby when Jupiter's magnetic field swept through at a different angle, which would have reversed the poles of any induced field. Sure enough, it was flipped. To produce the observed induced field in a model, the group had to assume that rock about 50 kilometers beneath the surface was completely molten or nearly so.

“Khurana's result is very interesting but ambiguous,” says planetary geophysicist David Stevenson of the California Institute of Technology in Pasadena. The magnetic data do require substantial melting of rock in a continuous layer around Io, he says, but sorting out the nature and geometrical arrangement of Io's deep magma ocean or global mush will require an Io orbiter.

13. FALL MEETING OF THE AMERICAN GEOPHYSICAL UNION, 14–18 DECEMBER 2009, SAN FRANCISCO, CALIFORNIA

# Antarctic Glacier Off Its Leash

1. Richard A. Kerr

An unmanned autonomous submarine has discovered a sea-floor ridge that may have been the last hope for stopping the now-accelerating retreat of the Pine Island Glacier, a crumbling keystone of the West Antarctic Ice Sheet, researchers announced at the fall meeting of the American Geophysical Union.

An unmanned autonomous submarine has discovered a sea-floor ridge that may have been the last hope for stopping the now-accelerating retreat of the Pine Island Glacier, a crumbling keystone of the West Antarctic Ice Sheet. The ridge appears to have once protected the glacier, but no more. The submarine found the glacier floating well off the ridge and warmer, ice-melting water passing over the ridge and farther under the ice. And no survey, underwater or airborne, has found another such glacier-preserving obstacle for the next 250 kilometers landward.

The Pine Island and adjacent Thwaites glaciers are key to the fate of West Antarctic ice, says glaciologist Richard Alley of Pennsylvania State University, University Park, in an e-mail. And West Antarctica is key to how fast and far sea level will rise in a warming world. “To a policymaker, I suspect that the continuing list of [such] ice-sheet surprises is not reassuring,” he writes.

At the meeting, glaciologist Adrian Jenkins of the British Antarctic Survey in Cambridge and colleagues described how the instrument-laden Autosub3 cruised for 94 hours along 510 kilometers of track beneath the floating portion of the Pine Island Glacier in January 2009. The sub found a 300-meter-high ridge across the ocean cavity formed by the floating end of the glacier. Deep, warmer water was overtopping the ridge and passing through the gap between floating ice and the ridge top on its way to melting back more of the glacier. That gap has been growing, Jenkins said, perhaps since the 1970s. An aerial photograph from 1973 shows a bump in the ice where the ridge is now known to be, suggesting that the ice was then resting on the ridge and no warmer water could have been getting through.

Although the last physical obstacle to continued melting and retreat of the Pine Island Glacier has been breached, the ice's fate remains murky, says glaciologist David Holland of New York University in New York City. That's because glaciologists aren't sure what got the glacial retreat started in the first place, he notes. It wasn't the greenhouse simply warming the ocean, researchers agree. Instead, shifting winds around Antarctica in recent decades may have driven warmer waters up to the ice and dislodged it from its perch on the ridge. But what caused the winds to shift? Global warming? The ozone hole? Random variability? Glaciologists—and policymakers—would like to know.

14. FALL MEETING OF THE AMERICAN GEOPHYSICAL UNION, 14–18 DECEMBER 2009, SAN FRANCISCO, CALIFORNIA

# Snapshots From the Meeting

1. Richard A. Kerr

Snapshots from the fall meeting of the American Geophysical Union include training people how to evacuate safely in the event of a tsunami and the finding that nanodiamonds really do litter the sedimentary record at the geologic moment that the mammoths disappeared.

Still no mammoth-killer. Nanodiamonds really do litter the sedimentary record at the geologic moment that the mammoths disappeared, geochemist Philippe Claeys of the Free University of Brussels and his colleagues reported at the meeting. A group of researchers has argued that the collision of a 4-kilometer-wide hypervelocity asteroid or comet created the minuscule jewels 12,900 years ago while wiping out all manner of megafauna (Science, 2 January 2009, p. 26). “There's really no doubt the nanodiamonds are there,” says Claeys. The problem is that they look just like the nanodiamonds found in modern soils in Belgium and Germany. And “a deliberate and detailed hunt” for the type of nanodiamond that forms only under the extreme conditions of an impact turned up nothing. So Claeys and colleagues—along with most researchers—still see no clear evidence for an impact.

Teach them, and they will flee. The hugely disastrous Sumatran tsunami of 2004 prompted the expansion of warning systems around the world, but that didn't do residents of the Samoan islands any good last September when a nearby earthquake shook them. More than 180 people died before any official warning could reach them. Even so, “there's no doubt training saved lives,” says oceanographer Walter Dudley of the University of Hawaii, Manoa, who—with his colleagues—interviewed survivors. The number of saved lives “is certainly in the hundreds, if not the thousands,” says Dudley. In preceding months, many islanders had received training from the Department of Homeland Security in how to respond to strong ground shaking. In one reported case, the shaking prompted more than 800 children and adults at a coastal school to evacuate safely to higher ground. In minutes, the tsunami destroyed their school. Says Dudley: “Our experience is, when people know what to do, they won't be victims.”