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SATELLITE-GUIDED BOMBS: GPS and the Next War

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ASTROPHYSICS 34 Magnetars BY CHRYSSA KOUVELIOTOU, ROBERT C. DUNCAN AND CHRISTOPHER THOMPSON Intensely magnetic neutron stars alter the quantum physics of their surroundings.

NEUROBIOLOGY 44 Why? The Neuroscience of Suicide BY CAROL EZZELL Brain chemistry might explain why some people impulsively choose to end their lives.

INFORMATION TECHNOLOGY 52 Evolving Inventions BY JOHN R. KOZA, MARTIN A. KEANE AND MATTHEW J. STREETER Using Darwinian evolution, computer programs can create patentable inventions.

ENVIRONMENT 60 Explaining Frog Deformities BY ANDREW R. BLAUSTEIN AND PIETER T. J. JOHNSON The alarming increase in abnormal amphibians has three primary causes. 52 Better WEAPONRY circuits through evolution. 66 Satellite-Guided Munitions BY MICHAEL PUTTRÉ Global Positioning System data make “dumb” bombs “smart” and deadly accurate.

MEDICINE 74 Drink to Your Health? BY ARTHUR L. KLATSKY Alcohol in moderation offers cardiovascular beneﬁts, but what should that mean to drinkers?

www.sciam.com SCIENTIFIC AMERICAN 3 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. departmentsSCIENTIFIC AMERICAN Volume 288 Number 2 6SA Perspectives A bad law hurts vaccination efforts. 7How to Contact Us 7 On the Web 90 32 8Letters 12 50, 100 & 150 Years Ago 27 Staking Claims 14 News Scan The bizarre world of business-method patents. ■ Greenhouse lawsuits against the government. 28 Innovations ■ Massaging clinical trial data. Drug trials in virtual patients. ■ Mass knockout gas. 32 Profile: Troy Duster ■ T cell transplants combat cancer. Even if race is largely a genetic myth, this sociologist ■ Giant-size quantum cats. argues, it is an epidemiological reality. ■ Rubber-band security. ■ By the Numbers: Evolution of religion. 82 Working Knowledge ■ Data Points: Oil spills. Artificial diamonds. 84 Technicalities Robots for the rest of us. 88 Reviews T CELL ATTACKS CANCER 18 A Shortcut through Time is an essential guide to the emergence of quantum computing. columns 31 Skeptic BY MICHAEL SHERMER Why scientists doubt ESP and psi phenomena. 90 Puzzling Adventures BY DENNIS E. SHASHA Choosing trustworthy flares. 92 Anti Gravity BY STEVE MIRSKY Moon-landing lunacy. 93 Ask the Experts Why do some people get more cavities than others? Why are snowflakes symmetrical? 94 Fuzzy Logic BY ROZ CHAST

Cover image by Don Dixon.

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No Immunity to Pork

Critics may gripe about whether the new Homeland from children’s vaccines, although medical authorities Security Act fights terrorism well, but no one can say generally maintain that the mercury exposure was too it doesn’t do a great job of protecting drug companies low to cause autism’s neurological defects. Studies from autistic children. have repeatedly failed to find an epidemiological tie be- A short provision at the end of the act, added qui- tween vaccines and autism, but an Institute of Medi- etly just days before its passage, exempts Eli Lilly and cine review in 2001 concluded that the thimerosal the- other firms from direct civil litigation over whether ory was “biologically plausible,” and so investigation vaccine additives cause autism. Parents suing on behalf continues. of their autistic children are shunted to a federal “vac- The U.S. needs a better, comprehensive strategy for cine court,” where damages are vaccines. Vaccines are the most effective public health capped. Conveniently, in late measure ever devised, but drug companies are reluc- November 2002 the Justice De- tant to work on them because the profitability is low partment also requested that the and the liability risks are high. If we want new vaccines court seal documents relating to against bioweapons such as smallpox, we will proba- hundreds of the lawsuits, com- bly need to give the pharmaceutical industry more in- plicating the cases for plaintiffs. centives and protection. Senator Bill Frist of Tennessee Ever since these shameful de- outlined one such scheme in 2002, but his proposal velopments became public, they caught legislative flu and died. have drawn bipartisan scorn. Then, presto: language crafted as a shield against Beyond the provision’s offen- thimerosal torts suddenly materialized at the end of the siveness as political pork, it is nearly 500-page Homeland Security Bill. No one—not harmful to lifesaving vaccina- Eli Lilly, not administration officials, not committee VACCINATION FEARS are fed by tion efforts. members who oversaw the bill—will admit to having bad legislation. Worries about childhood inserted the vaccine rider. It just appeared, a Thanks- vaccines and autism stretch back giving miracle for drugmakers. for years. Studies suggest that rates of autism may have The provision does nothing to promote new vac- as much as tripled in the past decade. Autism’s first cine development. By lending support to the impres- symptoms often emerge around age two, shortly after sion that the industry has something to hide, it fuels most infants start to receive vaccinations against distrust of vaccines—exactly when better data absolv- measles, whooping cough and other illnesses. Because ing the drugs are emerging. Consequently, too many the number of vaccinations that children receive has also parents are denying their children vaccinations that skyrocketed, concerned parents sought a linkage, and could save them from potentially fatal diseases. they found one in thimerosal, a mercury compound Here’s a suggestion: If no one will accept respon- used as a preservative in many vaccines. Some symp- sibility for the mysterious legislation, would any of its toms of autism resemble those of mercury poisoning. beneficiaries like to repudiate it? To ask for the repeal As a precaution, in 1999 the Food and Drug Ad- of the rider so that vaccine policies can be debated in-

ministration ordered the elimination of thimerosal telligently, as they deserve? Anyone? SATURN STILLS/SPL/PHOTO RESEARCHERS, INC.

THE EDITORS [email protected]

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for processing. fax: +852-2528-9281 www.sciam.com/marketplace NASA www.sciam.com SCIENTIFIC AMERICAN 7 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. ® Letters EDITORS@ SCIAM.COM Established 1845 EDITOR IN CHIEF: John Rennie LETTER WRITERS OFTEN comment on the perceived sub- EXECUTIVE EDITOR: Mariette DiChristina stance—or lack thereof—of Scientific American’s articles. But MANAGING EDITOR: Ricki L. Rusting NEWS EDITOR: Philip M. Yam one correspondent takes the concept to an admirable level. SPECIAL PROJECTS EDITOR: Gary Stix “Graham P. Collins seems to be taking an overly skeptical, even REVIEWS EDITOR: Michelle Press SENIOR WRITER: W. Wayt Gibbs facetious, view of perpetual-motion research [‘There’s No Stop- EDITORS: Mark Alpert, Steven Ashley, ping Them,’ Staking Claims, October 2002]. Clearly, he has not Graham P. Collins, Carol Ezzell, Steve Mirsky, George Musser made a serious effort to investigate the matter fully,” writes CONTRIBUTING EDITORS: Mark Fischetti, Stephen Palmer of Plainfield, N.J. “For example, I have recently Marguerite Holloway, Michael Shermer, applied for a patent of a perpetual-motion device that has been Sarah Simpson, Paul Wallich proven to work perfectly and, indeed, perpetually. This amazing EDITORIAL DIRECTOR, ONLINE: Kristin Leutwyler SENIOR EDITOR, ONLINE: Kate Wong invention sets into motion an infinite number of virtual parti- ASSOCIATE EDITOR, ONLINE: Sarah Graham cles, which flicker in and out of existence every instant. I have WEB DESIGN MANAGER: Ryan Reid decided to call it ‘nothing.’ Like all entrepreneurs, I intend to make my fortune from royalties as ART DIRECTOR: Edward Bell SENIOR ASSOCIATE ART DIRECTOR: Jana Brenning soon as nothing is patented. I will follow the path of many wealthy dot-com pioneers, except that ASSISTANT ART DIRECTORS: I have a firm business plan: when I receive investment capital, I will promptly send nothing in Johnny Johnson, Mark Clemens return.” There’s nothing more we can add about this topic, but others weigh in on the substance PHOTOGRAPHY EDITOR: Bridget Gerety PRODUCTION EDITOR: Richard Hunt of the rest of the October issue below.

COPY DIRECTOR: Maria-Christina Keller COPY CHIEF: Molly K. Frances COPY AND RESEARCH: Daniel C. Schlenoff, Rina Bander, Shea Dean, Emily Harrison FUEL-CELL FOLLIES? quire only half the fuel energy.” In fact, cut down the trees EDITORIAL ADMINISTRATOR: Jacob Lasky “You would still have to the efﬁciency depends on electrical load. SENIOR SECRETARY: Maya Harty and pave everything over for roads.” This Although proton-exchange-membrane ASSOCIATE PUBLISHER, PRODUCTION: William Sherman was an answer given by a fourth-grade fuel-cell systems can achieve an efﬁcien- MANUFACTURING MANAGER: Janet Cermak student when I asked what environmen- cy of 50 percent under low loads, it is un- ADVERTISING PRODUCTION MANAGER: Carl Cherebin PREPRESS AND QUALITY MANAGER: Silvia Di Placido tal effects cars would have if they were likely that they would be operated in this PRINT PRODUCTION MANAGER: Georgina Franco powered by a nonpolluting source of en- manner in a production vehicle. PRODUCTION MANAGER: Christina Hippeli CUSTOM PUBLISHING MANAGER: Madelyn Keyes-Milch ergy, such as hydrogen fuel cells [“Vehi- The article also neglects to account cle of Change,” by Lawrence D. Burns, for losses associated with deriving hy- ASSOCIATE PUBLISHER/VICE PRESIDENT, CIRCULATION: Lorraine Leib Terlecki J. Byron McCormick and Christopher E. drogen from other energy sources. Hy- CIRCULATION MANAGER: Katherine Corvino Borroni-Bird]. drogen will initially be obtained by re- CIRCULATION PROMOTION MANAGER: Joanne Guralnick FULFILLMENT AND DISTRIBUTION MANAGER: Rosa Davis The biggest impact of private motor forming natural gas, a process with, at

PUBLISHER: Bruce Brandfon vehicles is the creation of sprawling land best, an efﬁciency of 85 percent. ASSOCIATE PUBLISHER: Gail Delott use, which in turn causes forced depen- The authors list problems with storing SALES DEVELOPMENT MANAGER: David Tirpack dency on cars. Fuel-cell cars would also hydrogen, yet they fail to note how seri- SALES REPRESENTATIVES: Stephen Dudley, Hunter Millington, Stan Schmidt, Debra Silver still injure millions of Americans in colli- ous these are. A tank with hydrogen at the

ASSOCIATE PUBLISHER, STRATEGIC PLANNING: Laura Salant sions, another problem with personal suggested 350 bar would be about 10 PROMOTION MANAGER: Diane Schube transportation, and would still leave times as large in volume as one holding RESEARCH MANAGER: Aida Dadurian PROMOTION DESIGN MANAGER: Nancy Mongelli stranded the one third of the U.S. popula- gasoline with the same energy content. In

GENERAL MANAGER: Michael Florek tion that doesn’t drive. Cars would still sit addition, the energy required to compress BUSINESS MANAGER: Marie Maher in traffic jams and average a lower effec- and transport hydrogen by pipeline or MANAGER, ADVERTISING ACCOUNTING tive speed than bicycles. We can do much truck to the point of use is three to four AND COORDINATION: Constance Holmes better with transportation and land use. times as great for hydrogen as for natur- DIRECTOR, SPECIAL PROJECTS: Barth David Schwartz Robert Bernstein al gas on a per-unit energy basis. MANAGING DIRECTOR, SCIENTIFICAMERICAN.COM: Mina C. Lux Transportation chair The transformation to a vehicle fleet Sierra Club–Santa Barbara Group powered by hydrogen fuel cells would re- DIRECTOR, ANCILLARY PRODUCTS: Diane McGarvey PERMISSIONS MANAGER: Linda Hertz Goleta, Calif. quire an extensive and expensive change MANAGER OF CUSTOM PUBLISHING: Jeremy A. Abbate in the fuel-supply infrastructure but re- CHAIRMAN EMERITUS: John J. Hanley “Vehicle of Change” fails to discuss the sult in only marginal efficiency gains. CHAIRMAN: Rolf Grisebach PRESIDENT AND CHIEF EXECUTIVE OFFICER: challenges facing fuel cells. For one, the From an environmental standpoint, there Gretchen G. Teichgraeber authors state: “The hydrogen fuel-cell ve- is minimal reduction in greenhouse-gas VICE PRESIDENT AND MANAGING DIRECTOR, INTERNATIONAL: Charles McCullagh hicle is nearly twice as efficient as an in- production when hydrogen comes from

VICE PRESIDENT: Frances Newburg ternal-combustion engine, so it will re- reforming carbon-based fuels, because GENERAL MOTORS

The auto industry is not interested in making fuel-efficient vehicles because the CAR BODIES would sit atop public is not interested in purchasing a “skateboard” chassis in the such vehicles. Just look at the top-selling General Motors fuel-cell concept vehicle. cars in the 1990s—SUVs and pickup of leadership deserves most of the blame trucks. This is called supply and demand. carbon dioxide is a by-product. Further for a failing American energy policy and Until we have fuel-cell cars, let’s try buy- problems relating to safety, fuel-cell stack our appalling consumption of petroleum. ing already available efficient vehicles. As life and refueling methods are significant. The U.S. consumes 45 percent of the for me, I like my motorcycle. It would be far more productive to focus world’s gasoline but has 5 percent of the Mark Baker on hybrid-electric internal-combustion planet’s population. Still, our lawmakers Cuddebackville, N.Y. vehicles, mass-transportation concepts can’t pass a five-cent gas tax or close fuel- and smaller, lighter vehicles. economy loopholes big enough for mil- HOPE FOR SPINAL INJURIES S. A. Klein and D. T. Reindl lions of pickups and SUVs. We need an I’d like to point out a misconception about Department of Mechanical Engineering energy policy that reduces petroleum spinal-cord injuries raised by “Controlling University of Wisconsin–Madison consumption through conservation and Robots with the Mind,” by Miguel A. L. substitution starting now. Instead we get Nicolelis and John K. Chapin. The au- Perspectives describes how automak- “the hydrogen economy,” a far-fetched thors state that scientists may be able to re- ers use fantastic future technology pro- scheme that is well into the future and pair spinal-cord breaks in the distant fu- grams to obscure their more immediate will probably stay there. Greenwashing ture. Although this may be true, most peo- and less lofty motives. You chide the au- won’t hide the ugly truth of armed con- ple with spinal-cord injuries (including tomakers for this greenwashing, but you flict as energy policy. myself) have contusion injuries: the cord spare the government officials who co- Tom Gage is not cut. Because this is a simpler prob-

JOE ZEFF conspire in the charade. Their abdication Sunnyvale, Calif. lem, there are already promising thera-

pies for repairing damaged spinal cords that are either nearing or in clinical trials. Bruce Hanson Bellevue, Wash.

THE NAKED, AQUATIC APE? “Skin Deep,” by Nina G. Jablonski and George Chaplin, makes a good case for the evolution of melanin as a strategy for human reproductive success. But it gloss- es over the reason for such an adaptation: the loss of hair. The hypothesis presented, that our ancestors lost their hair to adapt to savanna life, is untenable on several grounds. First, other savanna- and desert-dwelling mammals have hair, which shades their skin and reduces heat stress. Second, humans did not lose the hair that covers our most heat-sensitive organ, the brain. It seems likely that another evolutionary force besides heat protection was responsible for human hairlessness. Al- though fossil evidence may be thin, the “aquatic ape” hypothesis makes sense. If our ancestors had taken to foraging for food along seacoasts, loss of hair and an increase in subcutaneous fat would have been adaptive as protection from the chilling effects of water. These adapta- tions are observed in most modern aquatic animals as well as in humans. Michael DeWeert Kailua, Hawaii

SHOCKED BY ELECTROSTATICS “Lightning Rods for Nanoelectronics,” by Steven H. Voldman, asserts that “people who like to tinker with their computers know that when they open up their machines, they should ‘ground’ themselves—perhaps by touching the metal ra- diator panel or attaching a wire from their ﬁngers to a metal ﬁxture.” Without a bit more detail, this information could be deadly. Obviously, unless someone is properly trained, any tinkering with electrical devices should be done with the power disconnected. Robert E. Fields Los Alamos National Laboratory Los Alamos, N.M.

Old Fish ■ New Cars ■ Blue Light

FEBRUARY 1953 lon. The characteristic of a high polymer por of mercury. On passing a direct cur- LIVING FOSSIL—“In the Indian Ocean off is that some chemical unit is linked to- rent through the lamp, the vapor which Madagascar, fishermen last month net- gether repeatedly to form a big structure. fills the tube is rendered incandescent and ted a five-foot, 100-pound fish which In nylon the unit is relatively simple, gives off a steady, blue-white light. Ow- evolutionists promptly hailed as the there being but one type of submolecule. ing to the great resistance at the negative ‘most important zoological discovery of In DNA the units are far more complex. electrode to the initial flow of current, it this century.’ J.L.B. Smith, South African To learn how they are polymerized to is necessary to use a high voltage to start ichthyologist, flew 3,000 miles in a gov- form a giant molecule is a formidable the lamp. The light given off by the in- ernment-supplied plane to reach the fish task which has not yet been accom- candescent vapor is entirely lacking in in time to preserve it. When he arrived, plished. When it is, we shall understand red rays, but on account of its wonder- and found it smelling somewhat strong better how DNA functions in the chro- fully low cost, the Cooper Hewitt light but largely intact, he broke down and mosome. —Alfred Ezra Mirsky” should be found very useful, without the wept. The object of his emotion was a addition of any rectifying light, for illu- coelacanth, the earliest type of bony fish. FEBRUARY 1903 minating factories, yards, etc., where the Until a few years ago it was believed that NEW CARS—“Three-quarters of the vehi- differentiating of colors is unimportant. such fish had been extinct for 75 million cles at the New York automobile show Another promising field for the new light years, but in 1938 one was pulled out of were of the internal-combustion cylinder is that of photography.” the water by a South African trawler. By type, the rest being steam or electric car- the time Smith got hold of it, only its riages. Prices ranged from $500 to $8,000. FEBRUARY 1853 skeleton and skin were left. Since that The entire absence of racing monsters INTERIOR OF THE EARTH—“Prof. Silliman, time he has been on a constant lookout was a sign of the tendency to build for of Yale College, says, ‘Heat in the earth for another specimen.” comfort, economy, and efficiency, with increases about one degree for every fifty moderate speed for touring purposes. If feet of descent; so that, if we were to go BEFORE WATSON AND CRICK—“An intact touring over the country is not popular down two miles, we should find boiling molecule of desoxyribonucleic [sic] acid, this coming season, it never will be.” water. Is all then beneath us on fire? There called DNA for short, is a very large, is strong evidence to justify such a theory. complicated structure: it may contain as MERCURY VAPOR LAMP—“Mr. George Witness the hot springs of Bath in Eng- many as 3,000 molecules of a 5-carbon Westinghouse, during his recent stay in land. These are the more remarkable as sugar. DNA is an example of what is London, exhibited the new lamp invent- there are no volcanoes in the British Is- nowadays called a high polymer. A fa- ed by Mr. Peter Cooper Hewitt. The lamp lands. We know that from the time of the miliar example of a high polymer is ny- consists of a glass tube filled with the va- Romans these waters have never ceased to gush up in vast abundance.’”

PAGING CAPTAIN NEMO—“Our engraving is a view of a partly submerged Propeller Torpedo Vessel, proposed by James Nas- myth, of Patricroft, England, for de- stroying large ships of an invading ﬂeet. The entire mass of the vessel (mortar and all) is brought into play, and the great brass mortar and shell explodes the instant it is crushed against the side of the enemy vessel. We must say that England seems afraid now of trusting in her wood- en walls, and instead of terrifying her foes by keeping watch on their coasts, as she once did, she is keeping a sharp look-out DUBIOUS COAST DEFENSE—the submarine mortar frigate, 1853 for the defence of her own coasts by such water hogs as this of Mr. Nasmyth.”

low-key case filed in a San Francisco greenhouse gas emissions or climate change.”) court last August promises to be just the The lawsuit does not attempt to cancel A first ripple. The suit, now with the ongoing projects but asks only that OPIC and Friends of the Earth, Greenpeace and the cities ExIm determine the “cumulative impact” on of Boulder, Colo., and Oakland, Calif., as the climate of every future project. Such a re- plaintiffs, seeks to force two government agen- view, asserts Jon Sohn of Friends of the cies to assess the total impact on climate of the Earth, is required by the National Environ- projects they finance. Rather than treaties and mental Policy Act. regulations, litigation may soon be the weap- The plaintiffs are confronted with many on of choice for those concerned about hu- hurdles. To begin with, they will have to dem- man-induced global warming. onstrate that they face harm from global In the San Francisco case, the warming and, in particular, from the agencies’ plaintiffs charge that in the past de- actions. The cities contend that their water cade, the Overseas Private Invest- supplies are in jeopardy. Boulder depends on ment Corporation (OPIC) and the runoff from mountain snow, but the snow- Export-Import Bank of the United pack at lower elevations has evaporated. Oak- States (ExIm) have provided $32 land fears that rising seas will salinate its un- billion in loans, insurance and loan derground aquifer. Other litigants include a guarantees for oil pipelines, oil drill- coral-reef scientist who finds that his object of ing and other fossil-fuel endeavors study is vanishing, and a couple who fear that that will ultimately result in the their island home will be washed away. emission of 32 billion tons of car- Scientific uncertainties over such claims bon dioxide over the life of the proj- can be partly overcome by aggregating harm ects. (All human activity currently done over a large span of space and time, con- emits about 24 billion tons of CO2 tends David Grossman, a recent graduate of a year.) In contrast, the agencies Yale Law School and now a law clerk in An- provided only $1.3 billion for re- chorage. In a paper to be published in the newable-energy projects during the Columbia Journal of Environmental Law,

same period. (A spokesperson for Grossman argues that tort litigation over AP Photo SEASIDE ESCAPE: The tiny Alaskan town of OPIC states in the agency’s defense global warming—in which communities or Shishmaref has voted to move inland to avoid the rising waters caused by climate warming. that OPIC-supported efforts are states seek damages from oil companies, elec-

not “major contributors to global tric utilities and automobile manufacturers— LAURA RAUCH

14 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. news is entirely feasible. The main problem is cau- $100 million), so they should stand a good sation—that is, proving that the defendant chance of a court upholding a claim that they SCAN caused harm to the plaintiff. Statistics can suffered damages because of global warming. help, he says, as when a town’s residents can A plaintiff’s next task would be to show attribute an enhanced frequency of cancer to that the defendants are meaningfully respon- a nearby pesticide plant. Thus, a homeowner sible. The issue will be vigorously fought, will probably not be able to show that the Grossman predicts. Environmentalists can es- hurricane that destroyed his house was timate the quantity of greenhouse gases for spawned by global warming, but the state of which, say, a large oil producer is responsible. WHOSE FAULT Florida may well prove that increased damage But calculating the fraction of warming is a far IS IT, ANYWAY? to coastal property over several years has a lot more contentious task, points out climatolo- A question one can ask is why to do with climate change. gist Stephen H. Schneider of Stanford Univer- energy producers or automakers In truth, sea-level rise and greater fre- sity, because of the inherent uncertainty and should be liable for emitting quency of storms are higher-order results of variability of climate models. Even so, Gold- greenhouse gases, as opposed to global warming, in that they would require berg holds that U.S. courts can solve the prob- consumers. Three answers: several links in a causal chain to be proved. An lem of apportioning blame: “It may take a few ■ There is no legal means of fixing easier case to make, notes Donald Goldberg cases, but ultimately the courts will ﬁgure out responsibility on consumers, of the Center for International Environmen- a formula for assigning responsibility.” whose individual emissions are tal Law in Washington, D.C., will simply be Shifting the cost of global warming to very small. warming. In Alaska, for example, average those who are disproportionately the perpe- ■ Consumers arguably have little temperatures have risen by about two degrees trators, Grossman argues, could make fossil choice in the matter, given that Celsius since 1970. Two coastal villages, Ki- fuels more expensive and thus force corpora- infrastructure and product valina and Shishmaref, have suffered from tions to pay more attention to renewable en- availability in most of the U.S. erosion that Gunter Weller of the University ergy. Environmental groups have been frus- makes high use of fossil fuels of Alaska–Fairbanks attributes to three fac- trated by the Bush administration’s rejection unavoidable. tors, all directly deriving from warming. Per- of the Kyoto treaty and what Sohn describes ■ Energy producers and other mafrost has thawed, causing houses to slide as its tendency to “deny, deﬂect blame and fossil-fuel corporations are in a off suddenly muddy cliffs; sea ice has thinned, delay” when it comes to issues involving glo- better position than consumers creating expanses of open water that rise up bal warming. So don’t be surprised if “See to internalize the costs of in ever higher storm surges; and glaciers are you in court” becomes the environmentalist’s climate change and to implement less damaging technology. The melting, leading local sea levels to climb (al- new rallying cry. consumer might ultimately have beit very slightly). The townships must be re- to pay anyway, through higher located (at an estimated cost of more than Madhusree Mukerjee is based in Darien, Ill. fossil-fuel prices.

HEALTH Bad Medicine WHY DATA FROM DRUG COMPANIES MAY BE HARD TO SWALLOW BY GUNJAN SINHA

etting drugs on the market means play- ministration approved Lotronex (alosetron ing games. So says Peter Lurie of Public hydrochloride), the first agent to treat the dis- G Citizen, an interest group founded by order specifically. As published in the Lancet, Ralph Nader and based in Washington, D.C. clinical trials in women revealed that 41 per- Of course, it’s the agency’s mission to be leery. cent taking the drug felt some relief, as did 29 But lately pharmaceutical companies are giv- percent taking a placebo. ing groups like Lurie’s more to be leery about. The data, Lurie insists, “are incredibly Drug firms now wield a great deal of control misleading.” One figure, for example, plots over their research, Lurie charges, and they percent change on one axis and time on the are frequently manipulating their data or other. First, plotting percent change instead withholding unfavorable results entirely. of absolute change makes the effectiveness of One of Public Citizen’s latest battles is the drug appear large. Second, the graph omits over a drug for irritable bowel syndrome data from the first month, during which the (IBS). Three years ago the Food and Drug Ad- drug and placebo worked almost identically.

from Baseline Baseline from 1.39

(percent) – 40 and an Pain 1.90 1.18 1.17 1 1.37 Me 1.12 1.08 Discomfort Score Discomfort

Change Alosetron Alosetron –50 0 0 1 2 3 0 1 2 3 Time of Treatment (month) Time of Treatment (month) BATTLE LINES: Lotronex (alosetron) appears to work much better than a placebo when percent change in pain severity from a baseline is plotted (left). Data replotted with absolute figures, done by the advocacy group Public Citizen, show much less of a difference (right). Both graphs appeared in the Lancet.

Public Citizen replotted the data using ab- drug hit the market in February 2000, the FDA solute values. The graph, which the Lancet assigned Paul D. Stolley of the University of published in a letter, better represents the Maryland to review the drug’s side-effects drug’s “marginal” efficacy, the group argues. profile. Stolley noticed a distressing pattern. “I don’t understand the accusation,” re- Day after day he would see reports of patients sponds Michael Camilleri of the Mayo Clin- being hospitalized, presumably because of ic in Rochester, Minn., who led the study. Lotronex. “This for a disease that never leads “Such presentation is standard and accepted to hospitalization, never perforates your colon in peer-reviewed scientific journals. The data and is not life-threatening,” Stolley points out. clearly show that the drug was better than the GlaxoSmithKline, the drug’s maker, pulled placebo for months two and three.” Lotronex off the shelves in November 2000 But many observers believe that drug after 49 reports of ischemic colitis and three companies go too far. “It shouldn’t happen in deaths. A few months later, responding in the scientific literature,” insists Bob Good- part to requests from IBS advocacy groups, man, founder of New York City–based No the company appealed to the FDA to bring the Free Lunch, which is focused on reining in the drug back. That move alarmed Stolley, who marketing ploys of drug companies. “Doctors felt that the risks far outweighed the drug’s should be able to decide the appropriateness marginal benefit. But when he spoke up, he of a drug. But how can they when drug com- was shut out. “FDA personnel were told not to panies leave out crucial information?” he discuss the case with me,” complained Stol- asks. Goodman is referring to another com- ley, who had consulted for the FDA for the mon practice: excluding data. past 30 years. Others were opposed to the Illustrating the point is the ongoing con- drug, but “they were intimidated,” says Stol- troversy over Cox-2 inhibitors, touted as a ley, who now works for Public Citizen. safer alternative to nonsteroidal anti-inflam- Some scientists argue that the FDA has be- matories such as ibuprofen. Sales of one, come so chummy with the drug industry Celebrex, reached a whopping $3 billion in partly because of the Prescription Drug User 2001. But last year the Washington Post re- Fee Act, passed in 1992. The act requires BAD NEWS vealed that Pharmacia, the drug’s maker, had firms to pay the FDA almost $500,000 in to- AS NO NEWS published just six months of results. Data for tal fees for each approved drug. Such fees ac- the next six months indicated that patients on count for almost half the agency’s cost of re- Academic researchers who carry out drug investigations may not Celebrex suffered complications such as viewing drugs. always be aware of data stomach ulcers at the same rate as those tak- “I was shocked the FDA buckled even af- manipulation. A recent study in the ing older medications. This information be- ter they’d seen the obfuscation and the at- New England Journal of Medicine came public only because one of the paper’s tempts to hide data. They seemed more com- surveyed 108 U.S. medical schools reviewers happened to be on the drug’s FDA fortable working with the company than with and found that only 1 percent of contracts between industry and review committee. Pharmacia says that the their own staff,” Stolley grouses. Lotronex is academic institutions required data for the last six months were too flawed now back on the market. But only authorized that every researcher of a to include them. doctors can prescribe it, and patients must multicenter study have access to There are also rumblings that even though sign an agreement stating that they fully un- all data. And less than 1 percent of the FDA is aware of such practices, the agency derstand the hazards. Here’s hoping that for contracts guaranteed that results would be published at all, ensuring is increasingly acting more favorably toward them, it is truly a risk worth taking. that negative results are drug companies. The Lotronex story again

not published. provides the spark for that charge. After the Gunjan Sinha is based in Frankfurt, Germany. JOHNNY JOHNSON

ast November 4 the Naval Studies Board hypnotic agents, anesthetic agents, muscle of the National Research Council issued relaxants, opioid analgesics, anxiolytics, anti- L a report calling on the U.S. to increase its psychotics and antidepressants. But they sin- PRESCRIPTION FOR research into “calmatives,” drugs that could gled out several major classes, two of which PACIFICATION be used to control and sedate unruly or hostile are convulsants and “selected drugs of According to the Naval Studies groups of people. Whereas most of the board’s abuse,” including certain “club drugs.” They Board, the U.S. worked on research had been ﬁnished a year earlier, the also pointed to two drugs deserving imme- calmatives in the 1980s and report was especially timely: nine days before, diate attention: diazepam (Valium) and 1990s at the army’s Edgewood Russian troops had used a gas to subdue dexmedetomidine. Chemical and Biological Command in Maryland. Moreover, it states Chechen rebels in an attempt to rescue the 700 Despite advances, drug delivery “remains that the use of calmatives has hostages they were holding in a Moscow the- a key issue in the development of calmative been discussed numerous times ater. The gas—actually a nebulized aerosol agents as nonlethal techniques,” the Penn re- during meetings held by the Office said to contain fentanyl, an opiate used as an searchers pointed out. The problem is one of of the Secretary of Defense and the anesthetic—killed more than 100 hostages. dosage: when an incapacitating gas is pumped Joint Staff. In May 2000 the Pentagon reportedly started at The U.S. looked into calmatives in the into the ventilation system of a building, as least one effort to research 1980s and 1990s, but the development of was the case in the Moscow theater, some re- chemical immobilizing agents. many types of chemical agents slowed or cipients will inevitably receive more than oth- Candidate compounds: stopped in the wake of the Chemical Weap- ers. An opiate such as fentanyl is particular- ■ Benzodiazepines ons Convention, ratiﬁed in 1997. The rise of ly crude when used in this way because it has terrorist activity throughout the world has led a small dosage window in which it is consid- ■ Alpha2-adrenoreceptor agonists many military experts to believe that some ered safe. Benzodiazepines, used to anes- ■ Dopamine D3 receptor agonists kind of knockout gas would be helpful. An- thetize and to treat anxiety and amnesia (Val- ■ Selective serotonin reuptake drew Mazzara, a retired U.S. Marine colonel ium is one), are considered more promising inhibitors

who heads the Institute for Emerging Defense but do not act as fast. ■ Serotonin 5-HT1A receptor Technologies at Pennsylvania State Universi- For these reasons, a nonlethal and effec- agonists ty’s Applied Research Laboratory, states that tive knockout gas is a myth, maintains Elisa ■ Opioid receptors and mu the Russian example highlights a need for Harris, a researcher at the University of Mary- agonists “more research rather than less” into non- land and a former National Security Council ■ Neurolept anesthetics

lethal means of incapacitating hostage takers. staff member. “I just can’t see how [such a ■ Corticotropin-releasing-factor Even before the Naval Studies Board, the gas] is technologically feasible,” she says. “In receptor antagonists

Penn State lab had investigated nonlethal decades and decades of research, it’s never ■ Cholecystokinin B receptor weapons and concluded that such calmative materialized.” Harris and other opponents ar- antagonists gases could work safely. Researchers led by gue that knockout gases Joan Lakoski, now at the University of Pitts- cannot be described as non- burgh, reviewed the medical literature on lethal—they will kill some pharmaceutical agents that produce “a calm of the people they are in- state.” Ideally, according to the investigators, tended to save. James Cot- an effective calmative would be easy to ad- trell, president of the Amer- minister and be adaptable for use in a variety ican Society of Anesthesiol- of forms, fast-acting but short-lived, and re- ogists, believes it would be versible. After examining more than 7,800 ar- “almost impossible” to de- ticles and other references, the Penn State team velop an anesthetic gas that declared in an October 2000 report that “the won’t kill. wide variety of drug classes and speciﬁc agents” One way to reduce ca- that they studied “serve to underscore that the sualties is to combine the

AP Photo development and use of nonlethal calmative use of a gas with postexpo- techniques is achievable and desirable.” sure treatment. Doctors in Moscow were re- GASSED VICTIM is carried by a The Penn State authors identiﬁed many portedly not aware of what ailed the rescued Russian officer after a raid to free hostages in a Moscow theater compounds that have a “high potential for hostages, which stymied their efforts to treat on October 26, 2002.

DMITRY LOVETSKY consideration” as nonlethal agents: sedative- them. Russian authorities denied the charge,

www.sciam.com SCIENTIFIC AMERICAN 17 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. news saying that antidotes were prepared and used. riots or even deny terrorists their targets.” SCAN In the end, determining whether a calma- Hostage negotiations should be tried ﬁrst, tive gas can be made safe and effective de- although in the case of the Moscow incident, pends on how those criteria are deﬁned. a peaceful end seemed unlikely. As Penn Whereas the gas used in Moscow killed more State’s Mazzara notes, without the use of cal- than 100 of the hostages, it contributed to the matives, such no-win situations might “very rescue of six times that many. Alan Zelicoff, possibly lead to more tragic results.” a senior scientist at Sandia National Labora- tories, remarks that “it might be nice to have Daniel G. Dupont, a frequent contributor, something other than high-speed lead, chem- edits InsideDefense.com, an online news ical explosives and other lethal means to quell service, from Washington, D.C.

CANCER T Cell Triumph IMMUNOTHERAPY MAY HAVE FINALLY TURNED A CORNER BY DIANE MARTINDALE

mmunotherapy for cancer is a targeted its method in two crucial ways. First, the sci- treatment that uses a patient’s own immune entists improved the way antitumor T cells are I cells to attack and destroy tumors. Highly generated. TILs were isolated from multiple touted when it was conceived in the early samples of each patient’s tumor and grown in 1980s, the approach has met with little suc- the lab. The group then tested up to 50 dif- cess. Now researchers think they may have ferent samples against each patient’s cancer gotten over the hump: they have successfully cells and chose the most reactive T cells to ex- treated several cases of a deadly skin cancer pand and reinfuse into the patients. Previous- with immune cells taken from the patients, ly, cells were simply extracted from the tu- grown in large numbers in the laboratory and mors without any type of selection. then given back to them. “We can now repop- Second, the researchers changed the way ulate the body’s immune patients are prepared be- system with cells that fight fore the treatment. This A TREATMENT the cancer,” says Steven A. time subjects underwent IN WAITING Rosenberg of the National robust chemotherapy to Cancer Institute, who pio- wipe out their immune sys- Despite the recent success, neered immunotherapy. tems temporarily and immune cell therapy is still highly experimental. Side effects were The idea is to exploit thereby make room for the serious in some cases: they a subset of T cells, the so- incoming tumor-killing T included vitiligo (white patches of called tumor-infiltrating cells. The procedure may skin where normal pigment cells lymphocytes (TILs), found have removed suppressor were attacked by the tumor- deep inside cancerous tis- cells (made by the immune infiltrating lymphocytes) and opportunistic infections. This is sue. These killer T cells at- system or the tumor), not like a drug you can just pull off tack the rapidly dividing which prevent T cells from T CELL (yellow) attacks a cancer cell. the shelf. “Every cell we give is cells and provide a natural proliferating, Rosenberg basically a different drug because protection against cancer. says. After the reinfusion, it’s unique to that patient. And But the body seldom makes enough to keep patients received repeated doses of interleukin every patient has a different kind of tumor,” says Steven A. the disease in check. 2, a potent immune system hormone that Rosenberg of the National Cancer Rosenberg first isolated and grew TILs and stimulates the growth of T cells. Institute, who is still trying to gave them to patients in the 1980s, in a pro- The study relied on 13 individuals with understand why the therapy works cess called adoptive T cell therapy. Although advanced metastatic melanoma, a skin cancer Photo Researchers, Inc. in some and not in others. the T cells retained their antitumor properties, that eventually spreads to other organs. The Rosenberg thinks it will be at least two years before the therapy they did not proliferate or survive long enough patients, who had exhausted all other treat- is ready for other types of in patients to kill their tumor cells. The recent ments, including surgery, received on average

cancer patients. success came when Rosenberg’s team altered 80 billion of their own TILs—enough to give EYE OF SCIENCE

18 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. news them a new immune system. As of December tients.” Moreover, “we are asking a lot of 2002, 10 of those subjects were still alive: six these T cells to treat patients with very large tu- SCAN had major remissions of their cancer, and four mor burdens,” says Cassian Yee, an immunol- had some of their tumors shrink. ogist who has developed a similar T cell trans- Analysis of patients’ blood and tumor fer therapy at the Fred Hutchinson Cancer Re- samples showed that the TILs multiplied and search Center in Seattle. “The T cell therapy then attacked the tumor tissue. “In the past might be more effective with smaller tumors when we transferred cells, maybe 1 or 2 per- and with repeated treatments over time.” cent survived,” Rosenberg explains. “Now we According to Figlin, the key to immuno- have 80 percent that survive for months, and therapy is selecting the right patients. “There when that happens the cancer disappears.” will be a smaller number of patients that have “The good news about Rosenberg’s work a higher response, and not the other way is that as a proof of principle, it’s extraordi- around,” he explains. “That’s the reality un- nary,” says Robert A. Figlin, an oncologist at til we understand the subtleties of the immune the University of California at Los Angeles response.” School of Medicine. “The bad news is that it’s not easily extrapolated to a large group of pa- Diane Martindale is based in Toronto.

PHYSICS Scaled-Up Superposition SUPERSIZING SCHRÖDINGER’S CAT—BY A BILLION TIMES BY CHARLES CHOI

ats may have nine lives, but only Schrö- of going down one of two paths, both capped dinger’s can be both alive and dead at with reflective cavities. The photon travels into C the same time. The quirky laws of quan- either cavity and bounces around inside for a tum mechanics suggest that objects can liter- while. It then eventually leaks out to head back STAKING A ally exist in two states or places simultane- to the beam splitter, where it is reconstituted SUPERPOSITION ously until perturbed in some way, after for detection. A photon will enter a superposi- Roger Penrose of the University of which they collapse out of this “superposition of traversing both paths simultaneously. Oxford conceived the experiment tion” to just one outcome. Physicists have cre- But one of the cavities is crucially differ- described in the main text because ated such Schrödinger’s cats before, usually in ent—one of its mirrors is mounted on an os- he thinks that the very fabric of the guise of a single particle—a photon or elec- cillating arm. Similar to a cantilever in atomic existence forbids large objects tron. That’s because the bigger the “cat,” the force microscopes, it would be sensitive from remaining in superposition for long. If something exists in two harder it is to keep it undisturbed, a necessary enough to detect the push felt by the mirror. places at once, it would result in condition for preserving the superposed state. The quivering mirror would end up being in a two different structures of space Physicists have come up with a scheme superposition for about a millisecond because and time, he says. Such a blister in they think will produce a Schrödinger’s cat bil- it was coupled to the photon. This super- reality represents an energy lions of times larger than before. That would position would appear as an interference pat- uncertainty; the larger the blister, the shorter the amount of time make it about the size of a feline cell—still a tern formed by the photon traveling two paths. each can stay apart. Whereas speck to human eyes but gigantic on the quan- The requirements for this experiment, de- electrons could exist in tum scale. Roger Penrose of the University of veloped with physicists William Marshall superposition for millions of years, Oxford originally conceived an experiment in and Christoph Simon, both at Oxford, are something the size of a dust mote space involving satellites, but collaborator exquisitely sensitive. The mirror has to be mi- would exist for just a second or so. Dik Bouwmeester of the University of Cali- nuscule to be jostled by a photon—maybe 10 The proposed experiment with fornia at Santa Barbara realized that a copycat microns thick (about a tenth the width of a mirrors won’t settle the question: version could be done on a tabletop, perhaps human hair) and five billionths of a gram in it would need 100,000 times more in three to five years as technology improves. weight. Temperature must be kept a few mil- mass to reach the regime in which The setup, a kind of interferometer, mon- lionths of a degree from absolute zero, to Penrose expects to see this cutoff in Schrödinger’s cat size. itors two paths that a photon of light can take. keep all vibrations to a minimum. Ultrahigh An experiment involving long A photon is directed toward a beam-splitting vacuum must be maintained to make sure a distances—such as orbiting crystal, which gives the light an equal chance stray atom doesn’t knock the arm askew. To- satellites—may be needed.

www.sciam.com SCIENTIFIC AMERICAN 19 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. news day’s technology can meet both temperature gests that in the future one could make this SCAN and vacuum conditions, but such a tiny mir- mirror on a carbon nanotube, a small but in- ror on an equally small arm challenges exist- credibly strong rod that researchers are still ing fabrication techniques. Bouwmeester sug- trying to perfect. “I would be quite surprised if a decade or Oscillating arm Fully so from now the experiment had not been Partially reflective Mirror reflective mirror done,” comments quantum physicist Paul mirror Kwiat of the University of Illinois at Urbana- Champaign. “Technology has a wonderful Path 1 tendency to improve, despite the aphorism Light Path 2 source ‘They don’t make ’em like they used to.’” Bouwmeester says that creating a large su- Beam perposition could improve quantum comput- splitter ers, which rely on particles in superposition to Detector Detector represent 0’s and 1’s simultaneously. The pro- GIANT QUANTUM CAT could be made if a photon is posed experiment, if successful, could help directed to a beam splitter, giving it two paths solve the problem of keeping these quantum to follow. The photon enters a superposition of cats trapped in superposition—and without traversing both paths—and takes the mirror on the scratches, either. the oscillating arm with it. The detector records the superposition as an interference signal. Charles Choi is based in New York City.

SECURITY Nothing but Net HOW NOT TO BREAK THE SAFETY BARRIER BY PHIL SCOTT

orld War II footage has that familiar in as little as three seconds. As the vehicle hits black-and-white scene: a heavily the net, the energy is absorbed by pistons in W damaged war bird lands out of con- the stanchions and the net—not unlike the trol on the stern of a straight-deck carrier and barriers on the WWII aircraft carriers, whose crashes into a steel cable net, which prevents nets had cables that folded down onto the it from ramming into aircraft waiting to take deck and were connected to energy-absorbing off. Volunteer ﬁreﬁghter Matthew Gelfand stanchions. was watching one such documentary in Gelfand, who received $650,000 from the 1993 when a lightbulb went on state of New York to develop GRAB through

above his head. He had heard his new company, Universal Safety Response, ) about an accident in which a envisions the system installed not only on rail- bottom car struck a train, then an- road crossings but also at tunnels, bridges and other vehicle whizzed past security gates on government buildings. Dur- the crossing and hit a fire- ing tests, the net could stop a 1,800-pound au- fighter. “If a carrier could tomobile traveling at 45 miles an hour in just catch a plane with a net, 13 feet. The quick stop did not inflict much why not a car with a net?” damage to the vehicle. Gelfand wondered. Last December the first GRAB was in- The result is GRAB, for stalled at a fitting location: the security en-

ground retractable automobile trance to the USS Intrepid, a WWII-era air- ); UNIVERSAL SAFETY RESPONSE, INC. (

barrier. Essentially, it is a tennis craft carrier converted to a ﬂoating aviation top net made from Kevlar strips, with two museum docked on New York City’s Hud- BETTER THAN A SPEED BUMP: metal stanchions on either side. Remote sen- son River. A retractable net can stop vehicles without damaging them. sors or a manual push button shoots the net

up from a two-inch-wide recess in the ground Phil Scott is based in New York City. SAMUEL VELASCO (

That burning sensation on the thighs The debate over the likelihood of liquid Martian may become a thing of the past for lap- water flows on. Researchers at the University of top computer users. Sandia National Colorado at Boulder and NASA conclude that Mars Laboratories researcher Michael Right- has generally been cold, dry and inhospitable. Wa- ley has devised a way to pipe comput- ter flowed only briefly in the past, they posit, when er heat out the side. He developed asteroids crashing into Mars billions of years ago “smart” heat pipes, made from 60-mi- unleashed scalding rains for decades at a time. cron-deep channels etched in copper. They calculate that the impact of a body 250 kilo- The self-contained system relies on meters wide would have delivered energy equiva- methanol in the tiny tubes. Heat from lent to 100 billion megatons of TNT to the planet, a chip or circuit board turns the liquid melting exposed polar ice and injecting enough wa- to gas, which moves warmth to the lap- ter into the atmosphere to rain out 16 meters of top edge, away from the lap. Once the precipitation. Life probably wouldn’t have had gas cools, it condenses and travels back time to evolve under such brief deluges, according to its start point via capillary action. to their report in the December 6, 2002, Science. A Rightley expects the method to replace more optimistic argument for the presence of run- laptop heat sinks, which are chunks of ning water on Mars came in a presentation at the metal, affixed next to the source, that American Geophysical Union, also in December. can handle up to 100 watts of heat per Scientists from the University of Arizona argued square centimeter. Today’s circuits that some of the dark streaks on the planet’s surface DATA POINTS: throw off about half as much, but fu- might be caused by current hydrological activity. OIL IN WATER ture chips will run hotter and may re- Very briny water, they say, could exist as a liquid at The fuel released last November off quire liquid cooling. The research will the low temperatures and pressures on Mars’s sur- the coast of Spain by the tanker appear in Microelectronics Journal. face and flow down slopes, leaving streaks with tell- Prestige could have long-lasting —Tariq Malik tale features in its wake. —Sarah Graham effects. In 2000 Christopher M. Reddy of the Woods Hole Oceanographic Institution and his colleagues drilled a 36-centimeter- long core in a West Falmouth, Mass., GEOCHEMISTRY marsh, near where the barge Florida ran aground in 1969 and spilled its oil. The team found that petroleum Fire and Ice contamination still persists there, more than 30 years later. Ice may seem an unlikely fire starter, but John Maclennan of the Paris Geo- Contaminated surface sediment physical Institute and his colleagues detected, in milligrams per gram beg to differ. They say that ancient vol- of soil, in 1976: 5.7 canoes in Iceland became suddenly In 2000, at the surface: 0 more active because of the abrupt In 2000, between 12 and 16 meltdown of kilometer-thick ice sheets centimeters down: 4 to 8

ILLUSTRATION BY MATT COLLINS that covered the island until about 10,000 years ago. Free of the ice’s Number of liters spilled by Florida: weight, the land popped up and relaxed VOLCANOES ROAR as glaciers recede. This particular 700,000 subglacial eruption occurred in Grimsvoetn, Iceland. Number of liters spilled pressure on the hot mantle rocks be- by Prestige: 10 million Corbis Sygma; low. The team’s analysis of massive lava ﬂows from that period provides the ﬁrst solid evidence that this pressure drop could cause

mantle rocks to melt and rise to the surface. The ﬂows—whose compositions indicate that SOURCE: Environmental Science they came from the mantle rather than the shallower crust—reveal a 30- to 100-fold jump in and Technology, November 15, 2002. Figures are approximate; eruption rates for the 1,500 years following the deglaciation. The new report appears in the contamination data from 2000 may 3 be slightly higher because of

HRAFNSSON GISLI EGILL November 5 G (Geochemistry, Geophysics, Geosystems). —Sarah Simpson improved detection sensitivity.

Recently discovered artifacts—plaque frag- discoverers think the bird is saying “King 3 ments and a seal—contain intriguing scripts Ajaw”: the Olmec used “3 Ajaw” to refer both that may be remnants of the ﬁrst written lan- to a day of the sacred, 260-day calendar and to guage in the New World. The pieces, found the king born on that day. The script predates near the Gulf coast of Tabasco, Mexico, be- other Mesoamerican writing by at least 250 longed to the Olmec people and date to 650 years and is the basis for subsequent Meso- B.C. The cylindrical seal shows a bird with american writing, including that of the Maya, symbols coming out of its beak, suggesting the researchers say. Other anthropologists, that the glyphs were spoken. The artifacts’ however, argue that the symbols could simply be drawings, rather than representations of speech. The artifacts are described in the De- —

cember 6, 2002, Science. Philip Yam ) bottom inset

BRIEF WRITTEN EVIDENCE: Olmec seal (left) has an etching POINTS of a bird apparently saying “King 3 Ajaw.” ■ The first high-quality draft of the mouse genome is now available. The rodent has about 30,000 genes, 99 percent of which have BIOLOGY counterparts in human DNA. Nature, December 5, 2002 Regenerating the Heart

■ Helicobacter pylori, the bacterium Scarring prevents human hearts from repair- of which are shared by humans—could lead to

that causes stomach ulcers, uses ); KENNETH D. POSS, LINDSAY G. WILSON AND MARK T. KEATING ( hydrogen as an energy source, ing themselves, but a common aquarium strategies for the scar-free repair of human

rather than carbohydrates, dweller now appears to hold a secret remedy. hearts. This work appears in the December 13, bottom ( as most bacteria do. Howard Hughes Medical Institute 2002, Science. —Sarah Simpson Science, November 29, 2002 investigators Kenneth D. Poss, Lindsay G. Wilson and Mark ■ Freshwater flows from Arctic T. Keating found that the rivers have increased with global warming and may zebraﬁsh can naturally re-

affect the oceans’ deep generate its own heart. Two Photo Researchers, Inc. circulation, resulting in a months after the surgical re- cooler northern Europe. moval of 20 percent of the Science, December 13, 2002 hearts of adult ﬁsh, the vital ); MARK SMITH organs had recovered their ■ Hazards of modern security: natural size and were beating A man being treated with radioactive iodine was properly. Under a microscope, strip-searched twice after the researchers could see that top left and right setting off radiation scar tissue clotted the wound detectors. Such patients initially, but proliferating mus- should carry a letter and a cle cells soon took over the 24-hour telephone number healing process. Future explo- of the physician in charge. QUICK FIX: Zebrafish can mend their broken hearts. The inset shows DNA ration of the ﬁsh’s regenera- Journal of the American Medical (green) that signals the successful regeneration of muscle cells (red).

Association, December 4, 2002 tion-promoting genes—many CHRISTOPHER VON NAGY (

BY THE NUMBERS Religion in America CHURCH ATTENDANCE HAS DIPPED, BUT FAITH REMAINS STRONG BY RODGER DOYLE SUNDAY SERMONS ot long ago many believed that the tury, in the early 1990s they still had more en- spread of science and education would tries than Catholics and Jews combined. Percent of U.S. adults surveyed cause religion to wither, but although Despite a long-standing schism between saying they attend church: N churchgoing has diminished, Americans gen- church doctrine and lay practice, particularly At least weekly: 24 to 30 erally retain their religious affiliations. Church on abortion and contraception, Catholicism Less than once a week: 54 to 58 attendance in the U.S. is higher than in any has managed to maintain the allegiance of European country except Ireland and Poland about a quarter of Americans over the past As a group, respondents typically [see By the Numbers, July 1999]. five decades. That is in part a result of higher overstate their attendance by Since at least the end of World War II, levels of natural increase and the reinforcing up to 70 percent. Protestantism has declined, reflecting a weak- effect of Catholic education. According to social scientist Father Andrew M. Greeley of the 80 Protestant University of Chicago, Catholics remain loy- al because they are powerfully attracted by the 70 experiences, images and traditions of the Church. The pedophile priest scandal, how- 60 ever, has taxed that loyalty: a Gallup poll in June 2002 reported that 22 percent of Catho- 50 lics said that they questioned whether they would remain in the fold. 40 The proportion of those adhering to Ju- daism has declined since World War II, in FURTHER 30 part because of low fertility and because mar- Catholic READING riages outside the faith (aided in part by a 20 shift from Orthodox toward Reform syna-

The Demographic Imperative in (percent) Americans of Preference gious No religious gogues) frequently result in disafﬁliation.

Religious Change in the United Reli preference Nevertheless, Judaism, at an estimated six States. Michael Hout, Andrew 10 Greeley and Melissa J. Wilde in Jewish million afﬁliates, remains the largest of the American Journal of Sociology, Other non-Christian religions, followed by Islam at 0 Vol. 107, No. 2; 2001. 1.9 million, Buddhism at 1.5 million and 1940 1960 1980 2000 Hinduism at about one million. Persistence and Change in the Year Protestant Establishment, SOURCE: National Opinion Research Center, General Social Survey The 1990s saw a substantial increase in 1930–1992. James D. Davidson, the proportion of Americans with no religious Ralph E. Pyle and David V. Reyes in ening of mainline denominations. A likely preference, mostly because of a shift in de- Social Forces, Vol. 74, No. 1; 1995. cause may be the lower fertility seen since the mographics, not a rise in religious skepticism. early 20th century, when women from these Young adults frequently disengage from reli- Why More Americans Have No Religious Preference: Politics denominations became active in the family- gion when leaving the parental home but and Generations. Michael Hout planning movement. In comparison with reengage after forming a family, but as a re- and Claude S. Fischer in evangelicals, who emphasize saving souls, sult of the recent trend toward marrying lat- American Sociological Review, mainline Protestants have been less active in er in life, for many that reengagement hasn’t Vol. 67, No. 2; 2002. recruiting new members. Despite the decline, happened yet. The percentage of adults raised Yearbook of American and members of the “Protestant establishment” with no religion rose from 3 to 6 percent over Canadian Churches 2002. churches—Episcopalians, Congregationalists, the past 30 years, but only about one third of Edited by Eileen W. Lindner. Presbyterians, Quakers and Unitarians—con- those without a religious preference can be Abingdon Press, 2002. tinue to hold positions of power in business, counted as nonbelievers. government, white-collar professions and the Next month: Fundamentalism. Handbook of Denominations in the United States. 11th edition. arts far out of keeping with their numbers. Al- Frank S. Mead and Samuel S. Hill. though their importance, as measured by list- Rodger Doyle can be reached at

Abingdon Press, 2001. ings in Who’s Who, fell during the 20th cen- [email protected] RODGER DOYLE

Take a Number Toilet reservations afford a glimpse of the world of business-method patents By GARY STIX

U.S. Patent 6,329,919 covers “an apparatus, system and Critics contend that many business methods fail to meet method for providing reservations for restroom use.” the standard that something being patented should not In 2001 the Patent and Trademark Office (PTO) deemed be obvious. They also assert that extending property IBM’s electronic toilet queue worthy of a patent, thus rights to broad areas beyond the sphere of technologi- fulfilling the office’s constitutional edict to “promote the cal invention can unfairly restrict economic activity. progress of science and useful arts.” You don’t have to “Should any one company be permitted to own the con- be a legal scholar to wonder whether IBM deserved to cept of frequent-flyer miles for 20 years?” asks Brian be given exclusive rights for near- Kahin, director of the University of Maryland Center for ly 20 years to stop others from de- Information Policy. Kahin is one of a number of intel- termining who gets to go next. The lectual-property scholars who think these patents IBM restroom patent joined Ama- should be eliminated or severely restricted. zon.com’s patent on one-click or- Business methods, which the appeals court held dering and countless lesser-known should be patentable as long as they are “useful, con- issuances from the PTO as mem- crete and tangible,” have made even the PTO squirm. In bers of the infamous subclass of 2000 the office started requiring that each application intellectual property known as evaluated in class 705 be reviewed by a second experi- business-method patents. enced examiner. Around 45 percent of applications filed A 1998 decision by the U.S. in class 705 are granted, compared with about 70 per- Court of Appeals for the Federal cent for patents in all classes. Because of the hurdles im- Circuit, State Street v. Signature posed by the PTO, Chicago intellectual-property attor- Financial Group, opened the ney Stephen Lesavich now counsels his clients to file ap- floodgates by throwing out a long- plications with the office in a way that avoids having standing judicial rule against busi- them classified as business-method patents. Applica- ness-method patents and giving a tions for these patents actually dropped by an estimat- boost to the gold-rush environment of the Internet ed 43 percent in fiscal 2002, fallout in part from the dot- boom—a dot-com company that sells dog food on the com bust. Web might now decide to apply for a patent on its Even IBM, the company that has garnered more method of doing business. After State Street, the num- patents of all types than any other for the past decade ber of applications for class 705 patents (patents on or so, had second thoughts about the one covering the business-related data-processing methods and tech- toilet queue. After Patent Commissioner James Rogan nologies) soared from 1,340 in the 1998 federal fiscal ordered a reexamination last year, IBM relieved itself of year to a peak of 8,700 in fiscal 2001. Ascertaining what the patent. “The company known as Big Blue does not a business-method patent is remains part of the prob- also want to be known as Big Loo,” noted the English lem. Among the difficulties: not all business-method Guardian. According to an IBM spokesperson, the cor- patents fit into class 705, and some of them predate the poration found that the patent did not meet its quality State Street decision. standards and decided to abandon it. A similar review The controversy surrounding intellectual property might be counseled elsewhere for other business-meth- on business methods has rivaled or exceeded disputes od patents, such as those for cutting hair, conducting an

JENNIFER KANE on software patents (a related area) and on gene patents. auction or privatizing government.

Reverse-Engineering Clinical Biology A peacetime dividend yields drug trials on virtual patients By GARY STIX

During the Star Wars years of the 1980s, Tom Paterson in decision analysis from Stanford University, a mecca worked at a defense think tank creating elaborate for modelers, Paterson went on to Strategic Decisions mathematical models to help military commanders Group (SDG), a California consultancy that did studies quickly decide which weapons to deploy to counter infor pharmaceutical companies about how to balance coming missiles. Inputs from hundreds of sensors had risks and payoffs in their overall drug-development to be combined to generate a consummate picture of portfolio. SDG decided to extend its expertise to help a events that would be unfolding in a matter of minutes, corporate customer perform “data mining” on complex enabling the fateful choice about when to launch. relational databases that tracked a patient’s illness over When the cold war ended, Paterson, like many dean extended period. “When our clients went in to mine fense engineers, tried to find a way to apply his skills the data, they were able to pull out things that they al- elsewhere. He ultimately took on a task that made shoot- ready knew, but they weren’t able to pull out anything ing down missiles seem pedestrian. A challenge faced by that was particularly novel,” Paterson recounts. A con- engineers in the Star Wars program—designing software nection between smoking and severe periodontal dis- to pick out critical targets despite an overload of data— ease, a link that Procter & Gamble had turned up in its carried over to simulations of how drugs work in the database, wasn’t exactly a revelation. metabolic and immune systems that drive the most For the answers, SDG turned to modeling. But mod- complex machine we know. els of biology are so complex that Paterson and his col- A few years later, after obtaining a master’s degree laborators could have spent the rest of their careers on a single cell. So the team—led by engineers, not biologists—did not begin at the cell nucleus and work toward a computerized rendition of Einstein. Rather the group adopted a reverse-engineering strategy, disas- sembling a disease in the way that a Ford engineer might take apart a Toyota to find out what the competition was doing. The model would identify mani- festations of the ailment and work back to the known biological pathways involved, while looking for new ones that had yet to be characterized. In the Procter & Gamble case, it started, for instance, with symptoms such as inflammation of the gums and then identified components of the immune system that contribute to periodontal disease. The modeling analysis suggested that the company should focus its search for fruitful drug targets on relatively overlooked areas of the in- nate immune system, which serves as an initial line of defense against a tide of invading pathogens. In the mid-1990s Paterson and his team at SDG METABOLIC PATHWAYS, represented by the rectangles that make up the grid, form the basis for Entelos’s model of a virtual diabetic patient. found that the continuing refinement of the technology

was stymied by the nature of its relationship with clients. COURTESY OF ENTELOS, INC.

28 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. To produce the models, the engineers at SDG relied on ing” a detailed technical description of a drug candi- the biological expertise provided by clients, but it was date, which then gets “metabolized” (subjected to a se- impossible to get the biologists they were working with ries of differential equations) in digital organs ranging to devote sufﬁcient time to these projects. “We really from the pancreas to the liver to the brain. The testing wanted [to have] life scientists on the team who would can demonstrate the effect of a drug based on weight, do nothing else,” Paterson remarks. “Not people who age, sex and degree of disease severity. If a drug makes were trying to squirrel away a couple hours a week it to market, Entelos often will receive royalties, which from their normal jobs.” As a consulting ﬁrm, howev- is somewhat unusual for an information provider. er, SDG was not about to hire a staff of biologists. The company has demonstrated that its PhysioLab By 1996 Paterson, software maven Alexander Bangs and a few others came up with a solution. They A virtual patient pops a pill by “swallowing” broke away from SDG to form Entelos, a corporation a detailed technical description whose name means “completely” in Greek. The work on periodontal disease and other models at SDG gave of a drug candidate, which then gets the start-up’s engineers principles to apply to maladies “metabolized” in digital organs ranging from ranging from asthma to diabetes. The elemental con- the pancreas to the liver to the brain. structs of the model, synthesized from thousands of journal articles, are different immunological or meta- system is more than a video game. The diabetes simu- bolic states in the body: for example, the concentration lation, for one, began to emerge more than three years of insulin in muscle tissue represents one of 700 such ago, when Johnson & Johnson signed up with Ente- variables in the diabetes model. To ensure that it is not los to test the obesity model and wanted it extended the collective delusion of a bunch of overcaffeinated en- to cover diabetes. Entelos did so by adding parameters gineers and biologists, the model is put through 350 such as hemoglobin A1c (a measure of average blood tests comparing the outputs with actual clinical data to sugar over the past three months). Johnson & Johnson validate its accuracy. then tried to mimic the dosing of patients involved in Pharmaceutical companies enter collaborative re- a clinical trial for a still proprietary antidiabetes drug search contracts with Entelos to run their drugs through candidate that worked in a novel way and for which it the models. A virtual patient pops a pill by “swallow- had no clinical data in humans. When the dose of the

compound was administered in virtual patients in five gradual steps, very few differences in therapeutic or toxic effects were registered from the lowest to the highest dose. So, in human trials, the company went immediately to the highest dose, avoiding clinical trials for each lesser dose that had been simulated and cutting the number of patients it needed by two thirds. The models cannot do everything, though. There were not enough data in the scientific literature to build a satisfactory model of fat cell growth and differentiation, for instance. Still, keen interest remains. Michael Jackson, a senior vice president at John- son & Johnson Pharmaceutical Research and Development, imagines that the PhysioLab might eventually be coupled with wireless monitoring devices in clinical trial patients. Every day or two the devices would broadcast information, such as blood pressure and glucose levels, to update the models constantly. The progress in simulating diabetes prompted the American Diabetes Association to form a partnership last year with Entelos, an attempt to draw in drug manufacturers to use modeling to speed new treatments for diabetes. The attention garnered by virtual patients has justified the early vision of En- telos’s founders. Paterson remembers that when he visited pharmaceutical companies in the late 1990s, officials would comment that this type of technology would soon become obsolete; they thought the Human Genome Project would reveal all disease genes and lead directly to new therapies. But the current vogue for “systems biology,” an attempt to go beyond the study of isolated genes and proteins, has lent support to the Entelos approach. This year the company will even supple- ment its simulations with real-life bench tops. It plans to construct a laboratory for cell-based testing at its new headquarters in Foster City, Calif. Thus, in silico biologists will adopt in vitro experimentation to get needed answers to questions that cannot be resolved by stringing together binary digits.

Psychic Drift Why most scientists do not believe in ESP and psi phenomena By MICHAEL SHERMER

In the first half of the 19th century the theory of evolution was are insignificant; the ganzfeld procedure places the “receiver” in mired in conjecture until Charles Darwin and Alfred Russel a room with Ping-Pong ball halves over the eyes and headphones Wallace compiled a body of evidence and posited a mechanism— over the ears playing white noise and the “sender” in another natural selection—for powering the evolutionary machine. room psychically transmitting visual images.) The theory of continental drift, proposed in 1915 by Alfred Despite the evidence for psi (subjects had a hit rate of 35 per- Wegener, was not accepted by most scientists until the 1960s, cent, when 25 percent was predicted by chance), Bem and Hon- with the discovery of midoceanic ridges, geomagnetic patterns orton lamented that “most academic psychologists do not yet corresponding to continental plate movement, and plate tec- accept the existence of psi, anomalous processes of information tonics as the driving motor. or energy transfer (such as telepathy or other forms of ex- Data and theory. Evidence and mechanism. These are the trasensory perception) that are currently unexplained in terms twin pillars of sound science. Without data and evidence, there of known physical or biological mechanisms.” is nothing for a theory or Why don’t scientists accept psi? Bem has a stellar reputation Until psi finds mechanism to explain. With- as a rigorous experimentalist and has presented statistically sig- its Darwin, out a theory and mechanism, nificant results. Aren’t scientists supposed to be open to chang- it will continue data and evidence drift aim- ing their minds when presented with new data and evidence? lessly on a boundless sea. The reason for skepticism is that we need replicable data and a to drift on the For more than a century, viable theory, both of which are missing in psi research. fringes of science. claims have been made for the Data. The meta-analysis and ganzfeld techniques have been existence of psi, or psychic phe- challenged. Ray Hyman of the University of Oregon determined nomena. In the late 19th century organizations such as the Soci- that there were inconsistencies in the experimental procedures ety for Psychical Research were begun to employ rigorous sci- used in different ganzfeld experiments (which were lumped to- entific methods in the study of psi, and they had world-class sci- gether in Bem’s meta-analysis as if they used the same proce- entists in support, including none other than Wallace (Darwin dures). He also pointed out flaws in the target randomization was skeptical). In the 20th century psi periodically appeared in process (the sequence in which the visual targets were sent to serious academic research programs, from Joseph B. Rhine’s ex- the receiver), resulting in a target-selection bias. Richard Wise- periments at Duke University in the 1930s to Daryl J. Bem’s re- man of the University of Hertfordshire in England conducted a search at Cornell University in the 1990s. meta-analysis of 30 more ganzfeld experiments and found no In January 1994, for example, Bem and his late University evidence for psi, concluding that psi data are nonreplicable. of Edinburgh parapsychologist colleague Charles Honorton Theory. The deeper reason scientists remain unconvinced published “Does Psi Exist? Replicable Evidence for an Anom- of psi is that there is no theory for how psi works. Until psi pro- alous Process of Information Transfer” in the prestigious review ponents can elucidate how thoughts generated by neurons in journal Psychological Bulletin. Conducting a meta-analysis of the sender’s brain can pass through the skull and into the brain dozens of published experiments, the authors concluded that of the receiver, skepticism is the appropriate response, as it was “the replication rates and effect sizes achieved by one particular for continental drift sans plate tectonics. experimental method, the ganzfeld procedure, are now sufficient Until psi finds its Darwin, it will continue to drift on the to warrant bringing this body of data to the attention of the fringes of science. wider psychological community.” (A meta-analysis is a statistical technique that combines the results from studies to look for Michael Shermer is publisher of Skeptic magazine

BRAD HINES an overall effect, even if the results from the individual studies (www.skeptic.com) and author of The Borderlands of Science.

The Reality of Race There’s hardly any difference in the DNA of human races. That doesn’t mean, argues sociologist Troy Duster, that genomics research can ignore the concept By SALLY LEHRMAN

Race doesn’t exist, the mantra went. The DNA inside suspect was Caucasian, Afro-Caribbean or Asian Indi- people with different complexions and hair textures is an merely by analyzing three sections of DNA. 99.9 percent alike, so the notion of race had no mean- “It was chilling,” recalls Francis S. Collins, director ing in science. At a National Human Genome Research of the institute. He had not been aware of DNA se- Institute (NHGRI) meeting five years ago, geneticists quences that could identify race, and it shocked him that were all nodding in agreement. Then sociologist Troy the information can be used to investigate crimes. “It Duster pulled a forensics paper out of his briefcase. It stopped the conversation in its tracks.” claimed that criminologists could find out whether a In large part thanks to Duster, Collins and other geneticists have begun grappling with forensic, epidemiological and pharmacogenomic data that raise the question of race at the DNA level. The NHGRI now routinely includes experts from the social disciplines to assist in guiding research priorities and framing the results for the public. “The complexities of the DNA sequence require not just simplistic statements about similarities between groups but a full appreciation of history, anthropology, social science and politics,” Collins has realized. “Duster is a person that rather regularly gets tapped on the shoulder and asked for help.” The urbane 66-year-old Duster, who splits his time between appointments at the University of California at Berkeley and New York University, examines how the public absorbs news about genetics into existing beliefs and how those perceptions also shape the use of genetic sequencing, DNA probes and other molecular techniques. Those techniques have revealed that race is minor at the DNA level. The genetic differences between any two TROY DUSTER: THINKING ABOUT GENES randomly selected individuals in one socially recognized population account for 85 percent of the variation one ■ Grandson of Ida B. Wells-Barnett, newspaper publisher, muckraker and might find between people of separate populations. Put antilynching crusader. another way, the genetic difference between two indi- ■ “The King of Coolocity,” says Harry G. Levine of Queens College, City viduals of the same race can be greater than those be- University of New York, because like a disciplined musician Duster tween individuals of different races—table sugar may combines seriousness, virtuoso skill, grace, balance and a relaxed look like salt, but it has more similarities with corn syrup. playfulness in his work (he is a jazz aficionado). But genetics cannot prove that race doesn’t exist, ■ Current worry: “It is almost inevitable that a research agenda will surface Duster explains. No amount of logic will erase the con- to try to find patterns of allele frequencies and then create computer- cept or destroy the disparities that arise from it, because

generated profiles of different types of criminals.” people use race to sort their social groupings and to de- ADAM FRIEDBERG

32 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. fine their social and economic interactions. Moreover, they do man genome research, Duster urged the NIH and the Depart- so in ways that have significant biological consequences. Duster ment of Energy to challenge The Bell Curve, the 1994 best-sell- recently helped to draft a 15-page statement for the American er that argued that race correlated with intelligence. Government Sociological Association showing how race persists as a factor in officials held up a response for eight months, convinced that the disparities in health and other areas of life. “You cannot just get nonexistence of race at the genome level spoke for itself. rid of the concept without doing tremendous damage to the epi- Duster, along with fellow committee member Dorothy demiologic research done so far,” Duster says. African-Ameri- Nelkin of New York University, highlighted the ways in which cans are three times as likely to die from heart disease, for ex- cultural context influences the application of medical and be- ample. “Blacks are redlined by banks, followed by department havioral genetics. Now Collins is relying on Duster and other store security, pulled over by the police. This can produce hy- collaborators, such as University of Wisconsin molecular biol- pertension,” he points out. “It can give you a heart attack.” ogist Pilar Ossorio, to help explain why race must be acknowl- A new approach, gene clustering, avoids race by dividing ac- edged even if it is biologically inconsequential. “It’s a tightrope cording to medically important markers, between trying to rescue the importance such as genes for the enzymes necessary to and meaning of research on race without metabolize drugs. But society will very giving it a false reality,” Duster says. likely re-create racial categories and rank- Indeed, although he maintains that ings under the new terms, Duster predicts. race is significant in genetics, Duster insists And by failing to name the social context, it is misleading to reinscribe race as a de- this strategy gives base-pair differences un- finitive system to group people who share due emphasis at the expense of environ- geographic origins and thus some genes. mental influences. Race is a social reality, For one, concepts of race vary geographi- Duster observes, and he warns that science cally as well as historically. The ethnic sta- itself is a social institution susceptible to es- tus of South Asians, for example, has sentialist perceptions of race. changed over the past century in the U.S. Raised in poverty during the Great De- and more often serves to define a political pression by a mother from an upper-class DNA PROFILES raise issues about race that and cultural “other” than something bio- family, Duster, whose father died when he sociologists such as Troy Duster must ponder. logical. In 1920 Oregon granted citizen- was nine, grew up navigating between ship to Bhagat Singh Thind of India dur- Chicago’s tough streets and its privileged intellectual and civic ing a ban on Asian immigration. But the U.S. Supreme Court dis- parlors. He witnessed firsthand the complexities of social cat- agreed, stating that even though Thind should be considered egories and learned to “code-switch” from one to another, “Caucasian,” he still wasn’t “white.” (Thind, who had joined much as he capably moves among sociology, anthropology and the U.S. Army during World War I, managed to stay in the coun- genetics now. try, earn a Ph.D. and publish 15 books on metaphysics.) Duster started out as a journalist but quit in moral indigna- Researchers have also advocated assessing health risks with- tion when chided for failing to interview a trapped subway mo- in ethnic groups based on inherited variations in just one DNA torman waiting for a leg amputation. He turned to sociology base pair. But such single-nucleotide polymorphism (SNP) pro- and joined Berkeley in 1967, quickly developing a reputation files can be deceptive, Duster warns. Ethnic differences in drug for thought-provoking work on drugs and social policy. In the metabolism or response to tobacco exist, but they appear to be 1970s Duster was a familiar voice in National Institutes of minimal and depend strongly on the environment. The empha- Health committees reviewing grants for research on mental sis on DNA, he remarks, transforms health status into a biolog- health and drug abuse. While sitting on a panel for President ical inevitability, and it is tempting to use the same tools to pro- Jimmy Carter’s Commission on Mental Health, he began to file criminality or intelligence at the genome level. hear researchers speculate that drug addiction and mental illness Specific variations in DNA can be linked to ancestral geo- were linked to genetic susceptibilities. graphic origins, but those differences only occasionally offer a Duster found the conversations alarming. His book, Back- medically important clue. They fail to define any essential char- door to Eugenics, aimed to stimulate public debate by showing acteristics of a whole group. Race, itself a fluid idea, is part of how genetic-screening policies tended to reinforce the power the environmental context of the genome, Duster suggests. “Race structures already within society. Since then, he has pressed ge- is a relationship,” he says. “When you talk about race as a rela- neticists and molecular biologists to consider the social mean- tionship, it prevents anyone from giving it false meaning.” Photo Researchers, Inc. ing that emerges from what they perceive as unbiased fact. At first they resisted. As a member of the Ethical, Legal and Sally Lehrman is a medical technology and health policy

TEK IMAGE Social Implications Working Group advising the agencies on hu- journalist based in San Francisco.

www.sciam.com SCIENTIFIC AMERICAN 33 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. STARQUAKE ON A MAGNETAR releases a vast amount of magnetic energy— equivalent to the seismic energy of a magnitude 21 earthquake—and unleashes a ﬁreball of plasma. The ﬁreball gets trapped by the magnetic field.

By Chryssa Kouveliotou, Robert C. Duncan and Christopher Thompson

On March 5, 1979, several months after dropping probes into the toxic atmosphere of Venus, two Soviet spacecraft, Venera 11 and 12, were drifting through the inner solar system on an elliptical orbit. It had been an uneventful cruise. The radiation readings on board both probes hovered around a nominal 100 counts per second. But at 10:51 A.M. EST, a pulse of gamma radiation hit them. Within a fraction of a millisecond, the radiation level shot above 200,000 counts per second and quickly went off scale. Eleven seconds later gamma rays swamped the NASA space probe Helios 2, also orbiting the sun. A plane wave front of high-energy radiation was evidently sweeping through the solar system. It soon reached Venus and saturated the Pioneer Venus Orbiter’s detector. Within seconds MAGNETARS

COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. the gamma rays reached Earth. They flooded detectors on three compelling evidence for that explanation. Recent observations U.S. Department of Defense Vela satellites, the Soviet Prognoz connect our theory to yet another class of celestial enigmas, 7 satellite, and the Einstein Observatory. Finally, on its way out known as anomalous x-ray pulsars (AXPs). These developments of the solar system, the wave also blitzed the International Sun- have led to a breakthrough in our understanding of one of the Earth Explorer. most exotic members of the celestial bestiary, the neutron star. The pulse of highly energetic, or “hard,” gamma rays was Neutron stars are the densest material objects known, pack- 100 times as intense as any previous burst of gamma rays de- ing slightly more than the sun’s mass inside a ball just 20 kilo- tected from beyond the solar system, and it lasted just two tenths meters across. Based on the study of SGRs, it seems that some of a second. At the time, nobody noticed; life continued calmly neutron stars have magnetic fields so intense that they radically beneath our planet’s protective atmosphere. Fortunately, all 10 alter the material within them and the state of the quantum vac- spacecraft survived the trauma without permanent damage. The uum surrounding them, leading to physical effects observed hard pulse was followed by a fainter glow of lower-energy, or nowhere else in the universe. “soft,” gamma rays, as well as x-rays, which steadily faded over the subsequent three minutes. As it faded away, the signal os- cillated gently, with a period of eight seconds. Fourteen and a MAGNETAR CANDIDATES half hours later, at 1:17 A.M. on March 6, another, fainter burst of x-rays came from the same spot on the sky. Over the ensu- ing four years, Evgeny P. Mazets of the Ioffe Institute in St. Pe- tersburg, Russia, and his collaborators detected 16 bursts com- 0142+61 1844–0258 1806–20 1627–41 ing from the same direction. They varied in intensity, but all were fainter and shorter than the March 5 burst. Astronomers had never seen anything like this. For want of a better idea, they initially listed these bursts in catalogues along- side the better-known gamma-ray bursts (GRBs), even though they clearly differed in several ways. In the mid-1980s Kevin C. Hurley of the University of California at Berkeley realized that 2259+586 1900+14 1841–045 1708–40 similar outbursts were coming from two other areas of the sky. Evidently these sources were all repeating—unlike GRBs, which TWELVE POSSIBLE magnetars have been are one-shot events [see “The Brightest Explosions in the Uni- detected in or near our Milky Way galaxy. verse,” by Neil Gehrels, Luigi Piro and Peter J. T. Leonard; Sci- entific American, December 2002]. At a July 1986 meeting in Toulouse, France, astronomers agreed on the approximate Not Supposed to Do That locations of the three sources and dubbed them “soft gamma re- BECAUSE THE MARCH 1979 BURST was so bright, theo- peaters” (SGRs). The alphabet soup of astronomy had gained rists at the time reckoned that its source was in our galactic a new ingredient. neighborhood, hundreds of light-years from Earth at most. If Another seven years passed before two of us (Duncan and that had been true, the intensity of the x-rays and gamma rays Thompson) devised an explanation for these strange objects, would have been just below the theoretical maximum steady and only in 1998 did one of us (Kouveliotou) and her team find luminosity that can be emitted by a star. That maximum, first derived in 1926 by English astrophysicist Arthur Eddington, is set by the force of radiation flowing through the hot outer Overview/Ultramagnetic Stars layers of a star. If the radiation is any more intense, it will over- ■ Astronomers have seen a handful of stars that put out power gravity, blow away ionized matter and destabilize the flares of gamma and x-radiation, which can be millions of star. Emission below the Eddington limit would have been fair- times as bright as any other repeating outburst known. ly straightforward to explain. For example, various theorists University of California at Los Angeles,

The enormous energies and pulsing signals implicate the proposed that the outburst was triggered by the impact of a ) second most extreme type of body in the universe chunk of matter, such as an asteroid or a comet, onto a nearby (after the black hole): the neutron star. neutron star. above ■ These neutron stars have the strongest magnetic fields But observations soon confounded that hypothesis. Each ); E. L. WRIGHT ever measured—hence their name, magnetars. Magnetic spacecraft had recorded the time of arrival of the hard initial instabilities analogous to earthquakes can account pulse. These data allowed astronomers, led by Thomas Lytton for the flares. Cline of the NASA Goddard Space Flight Center, to triangulate ■ Magnetars remain active for only about 10,000 years, the burst source. The researchers found that the position coin- preceding pages implying that millions of them are drifting undetected cided with the Large Magellanic Cloud, a small galaxy about through our galaxy. 170,000 light-years away. More speciﬁcally, the event’s posi-

tion matched that of a young supernova remnant, the glowing DON DIXON ( THE COBE PROJECT, DIRBE AND NASA (

36 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. remains of a star that exploded 5,000 years ago. Unless this or helium or to the sudden accretion of matter onto the star. But overlap was pure coincidence, it put the source 1,000 times as the brightness of the SGR bursts was unprecedented, so a new far away as theorists had thought—and thus made it a million physical mechanism seemed to be required. times brighter than the Eddington limit. In 0.2 second the March 1979 event released as much energy as the sun radiates Spin Forever Down in roughly 10,000 years, and it concentrated that energy in THE FINAL BURST FROM the March 1979 source was de- gamma rays rather than spreading it across the electromagnet- tected in May 1983; none has been seen in the 19 years since. ic spectrum. Two other SGRs, both within our Milky Way galaxy, went off No ordinary star could account for such energy, so the in 1979 and have remained active, emitting hundreds of bursts source was almost certainly something out of the ordinary—ei- in the years since. A fourth SGR was located in 1998. Three of ther a black hole or a neutron star. The former was ruled out these four objects have possible, but unproved, associations with by the eight-second modulation: a black hole is a featureless ob- young supernova remnants. Two also lie near very dense clus-

ROTATION SGR 1900+14 FLARE SGR 1900+14 ACTIVITY YEAR OF PERIOD DISCOVERY NAME (seconds) Flare 60 1048–59 SGR 0526–66 1979 8.0 Days SGR 1900+14 1979 5.16 40 SGR 1806–20 1979 7.47 r 20 SGR 1801–23* 1997 ? 20

SGR 1627–41 1998 ? Events pe NTENSITY AXP 1E 2259+586 1981 6.98 I 0 † 0 1 2 3 4 5 1980 '90 '00 AXP 1E 1048–59 1985 6.45 Minutes Year AXP 4U 0142+61 1993 8.69 GIANT X-RAY FLARE in August 1998 confirmed the existence 0110–72 0526–66 AXP 1RXS 1708–40† 1997 11.0 of magnetars. It started with a spike of radiation lasting less AXP 1E 1841–045 1997 11.8 than a second (left). Then came an extended train of pulses AXP AXJ1844–0258 1998 6.97 with a period of 5.16 seconds. This event was the most AXP CXJ0110–7211† 2002 5.44 powerful outburst to come from the object, designated SGR * Not shown on map; location not known precisely 1900+14, since its discovery in 1979 (right). † Abbreviated name

ject, lacking the structure needed to produce regular pulses. The ters of massive young stars, intimating that SGRs tend to form association with the supernova remnant further strengthened from such stars. A fifth candidate SGR has gone off only twice; the case for a neutron star. Neutron stars are widely believed to its precise location is still unknown. form when the core of a massive but otherwise ordinary star ex- As Los Alamos National Laboratory scientists Baolian L. hausts its nuclear fuel and abruptly collapses under its own Cheng, Richard I. Epstein, Robert A. Guyer and C. Alex Young weight, thereby triggering a supernova explosion. pointed out in 1996, SGR bursts are statistically similar to earth- Identifying the source as a neutron star did not solve the puz- quakes. The energies have very similar mathematical distribu- zle; on the contrary, it merely heightened the mystery. Astron- tions, with less energetic events being more common. Our grad- omers knew several examples of neutron stars that lie within su- uate student Ersin Gögüs of the University of Alabama at pernova remnants. These stars were radio pulsars, objects that Huntsville verified this behavior for a large sample of bursts are observed to blink on and off in radio waves. Yet the March from various sources. This and other statistical properties are a 1979 burster, with an apparent rotation period of eight seconds, hallmark of self-organized criticality, whereby a composite sys- was spinning much more slowly than any radio pulsar then tem attains a critical state in which a small perturbation can trig- known. Even when not bursting, the object emitted a steady ger a chain reaction. Such behavior occurs in systems as diverse glow of x-rays with more radiant power than could be supplied as avalanches on sandpiles and magnetic flares on the sun. by the rotation of a neutron star. Oddly, the star was signifi- But why would a neutron star behave like this? The solu- cantly displaced from the center of the supernova remnant. If it tion emerged from an entirely separate line of work, on radio was born at the center, as is likely, then it must have recoiled pulsars. Pulsars are widely thought to be rapidly rotating, mag- with a velocity of about 1,000 kilometers per second at birth. netized neutron stars. The magnetic field, which is supported Such high speed was considered unusual for a neutron star. by electric currents flowing deep inside the star, rotates with the Finally, the outbursts themselves seemed inexplicable. X-ray star. Beams of radio waves shine outward from the star’s mag- flashes had previously been detected from some neutron stars, netic poles and sweep through space as it rotates, like lighthouse but they never exceeded the Eddington limit by very much. As- beacons—hence the observed pulsing. The pulsar also blows

SOURCE FOR TABLE: CHRYSSA KOUVELIOTOU, ROBERT C. DUNCAN AND CHRISTOPHER THOMPSON tronomers ascribed them to thermonuclear fusion of hydrogen out a wind of charged particles and low-frequency electromag-

www.sciam.com SCIENTIFIC AMERICAN 37 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. netic waves, which carry away energy and angular momentum, tromagnetism, as a magnetized object shrinks by a factor of two, causing its rate of spin to decrease gradually. its magnetic field strengthens by a factor of four. The core of a Perhaps the most famous pulsar lies within the Crab Nebu- massive star collapses by a factor of 105 from its birth through la, the remnant of a supernova explosion that was observed in neutron star formation, so its magnetic field should become 1010 1054. The pulsar rotates once every 33 milliseconds and is cur- times stronger. rently slowing at a rate of about 1.3 millisecond every century. If the core magnetic field started with sufficient strength, this Extrapolating backward, it was born rotating once every 20 compression could explain pulsar magnetism. Unfortunately, milliseconds. Astronomers expect it to continue to spin down, the magnetic field deep inside a star cannot be measured, so this eventually reaching a point when its rotation will be too slow to simple hypothesis cannot be tested. There are also good reasons power the radio pulses. The spin-down rate has been measured to believe that compression is only part of the story. for almost every radio pulsar, and theory indicates that it de- Within a star, gas can circulate by convection. Warm parcels pends on the strength of the star’s magnetic field. From this, of ionized gas rise, and cold ones sink. Because ionized gas con- most young radio pulsars are inferred to have magnetic fields be- ducts electricity well, any magnetic field lines threading the gas tween 1012 and 1013 gauss. For comparison, a refrigerator mag- are dragged with it as it moves. The field can thus be reworked net has a strength of about 100 gauss. and sometimes amplified. This phenomenon, known as dynamo action, is thought to generate the magnetic fields of stars and The Ultimate Convection Oven planets. A dynamo might operate during each phase of the life of THIS PICTURE LEAVES a basic question unanswered: Where a massive star, as long as the turbulent core is rotating rapidly did the magnetic field come from in the first place? The tradi- enough. Moreover, during a brief period after the core of the star tional assumption was: it is as it is, because it was as it was. That turns into a neutron star, convection is especially violent. is, most astronomers supposed that the magnetic field is a relic This was first shown in computer simulations in 1986 by of the time before the star went supernova. All stars have weak Adam Burrows of the University of Arizona and James M. Lat- magnetic fields, and those fields can be amplified simply by the timer of the State University of New York at Stony Brook. They act of compression. According to Maxwell’s equations of elec- found that temperatures in a newborn neutron star exceed 30 TWO TYPES OF NEUTRON STARS

Most neutron stars Massive stars die A: If the newborn neutron A: The magnetar settles A: The old magnetar has 1are thought to begin 2in a type II 3star spins fast enough, 4into neat layers, with 5cooled off, and much as massive but supernova explosion, it generates an intense twisted field lines inside and of its magnetism has otherwise ordinary as the stellar core magnetic field. Field lines smooth lines outside. It might decayed away. It emits stars, between eight implodes into a dense inside the star get twisted. emit a narrow radio beam. very little energy. and 20 times as heavy ball of subatomic as the sun. particles. Age: 0 to 10 seconds Age: 0 to 10,000 years Age: above 10,000 years

NEWBORN NEUTRON STAR MAGNETAR

B: If the newborn neutron B: The mature pulsar is B: The old pulsar has 3star spins slowly, its 4cooler than a magnetar of 5cooled off and no longer magnetic field, though strong equal age. It emits a broad emits a radio beam. ORDINARY PULSAR by everyday standards, does radio beam, which radio not reach magnetar levels. telescopes can readily detect. Age: 0 to 10 seconds Age: 0 to 10 million years Age: above 10 million years

38 SCIENTIFIC AMERICAN COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. billion kelvins. Hot nuclear fluid circulates in 10 milliseconds or gauss; beyond this limit, the fluid inside the star would tend to less, carrying enormous kinetic energy. After about 10 seconds, mix and the field would dissipate. No known objects in the uni- the convection ceases. verse can generate and maintain fields stronger than this level. Not long after Burrows and Lattimer conducted their first One ramification of our calculations is that radio pulsars are simulations, Duncan and Thompson, then at Princeton Univer- neutron stars in which the large-scale dynamo has failed to op- sity, estimated what this furious convection means for neutron- erate. In the case of the Crab pulsar, the newborn neutron star star magnetism. The sun, which undergoes a sedate version of rotated once every 20 milliseconds, much slower than the rate the same process, can be used as a reference point. As solar flu- of convection, so the dynamo never got going. id circulates, it drags along magnetic field lines and gives up about 10 percent of its kinetic energy to the field. If the moving Crinkle Twinkle Little Magnetar fluid in a newborn neutron star also transfers a tenth of its ki- ALTHOUGH WE DID NOT develop the magnetar concept to netic energy to the magnetic field, then the field would grow explain SGRs, its implications soon became apparent to us. The stronger than 1015 gauss, which is more than 1,000 times as magnetic field should act as a strong brake on a magnetar’s ro- strong as the fields of most radio pulsars. tation. Within 5,000 years a field of 1015 gauss would slow the Whether the dynamo operates globally (rather than in lim- spin rate to once every eight seconds—neatly explaining the os- ited regions) would depend on whether the star’s rate of rota- cillations observed during the March 1979 outburst. tion was comparable to its rate of convection. Deep inside the As the field evolves, it changes shape, driving electric currents sun, these two rates are similar, and the magnetic field is able along the field lines outside the star. These currents, in turn, gen- to organize itself on large scales. By analogy, a neutron star erate x-rays. Meanwhile, as the magnetic field moves through born rotating as fast as or faster than the convective period of the solid crust of a magnetar, it bends and stretches the crust. 10 milliseconds could develop a widespread, ultrastrong mag- This process heats the interior of the star and occasionally breaks netic field. In 1992 we named these hypothetical neutron stars the crust in a powerful “starquake.” The accompanying release “magnetars.” of magnetic energy creates a dense cloud of electrons and An upper limit to neutron-star magnetism is about 1017 positrons, as well as a sudden burst of soft gamma rays—accounting for the fainter bursts that give SGRs their name. More infrequently, the magnetic field becomes unstable and undergoes a large-scale rearrangement. Similar (but smaller) up- heavals sometimes happen on the sun, leading to solar flares. A magnetar easily has enough energy to power a giant flare such as the March 1979 event. Theory indicates that the first half-sec- ATMOSPHERE OUTER CRUST ond of that tremendous outburst came from an expanding fireball. In 1995 we suggested that part of the fireball was trapped INNER CRUST by the magnetic field lines and held close to the star. This trapped fireball gradually shrank and then evaporated, emitting x-rays all the while. Based on the amount of energy released, we calculated the strength of the magnetic field needed to confine the enormous fireball pressure: greater than 1014 gauss, which agrees with the field strength inferred from the spin-down rate. A separate estimate of the field had been given in 1992 by Bohdan Paczynski ´ of Princeton. He noted that x-rays can slip QUARKS? CHRYSSA KOUVELIOTOU, ROBERT C. DUNCAN and CHRISTOPHER THOMPSON have studied magnetars for a collective 40 years and have collaborated for the past five. Kouveliotou, an observer, CORE works at the National Space Science and Technology Center in Huntsville, Ala. Besides soft-gamma repeaters, her pets include gamma-ray bursts, x-ray binaries and her cat, Felix; her interests THE AUTHORS range from jazz to archaeology to linguistics. Duncan and Thomp- son are theorists, the former at the University of Texas at Austin, the latter at the Canadian Institute for Theoretical Astrophysics in 5 KM Toronto. Duncan has studied supernovae, quark matter and in-

DON DIXON tergalactic gas clouds. In his younger days he ran a 2:19 marathon STRUCTURE OF A NEUTRON STAR can be inferred from theories of nuclear matter. in the 1980 U.S. Olympic trials. Thompson has worked on topics Starquakes can occur in the crust, a lattice of atomic nuclei and electrons. The from cosmic strings to giant impacts in the early solar system. He, core consists mainly of neutrons and perhaps quarks. An atmosphere of hot too, is an avid runner as well as a backpacker. plasma might extend a grand total of a few centimeters. SCIENTIFIC AMERICAN 39 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. through a cloud of electrons more easily if the charged particles the Rossi X-ray Timing Explorer (RXTE), a satellite designed are immersed in a very intense magnetic field. For the x-rays dur- to be highly sensitive to variations in x-ray intensity. Using this ing the burst to have been so bright, the magnetic field must have instrument, Kouveliotou found that the emission from SGR been stronger than 1014 gauss. 1806–20 was oscillating with a period of 7.47 seconds—amaz- What makes the theory so tricky is that the fields are stronger ingly close to the 8.0-second periodicity observed in the March than the quantum electrodynamic threshold of 4 × 1013 gauss. 1979 burst (from SGR 0526–66). Over the course of five years, In such strong fields, bizarre things happen. X-ray photons read- the SGR slowed by nearly two parts in 1,000. Although the slow- ily split in two or merge together. The vacuum itself is polarized, down may seem small, it is faster than that of any radio pulsar becoming strongly birefringent, like a calcite crystal. Atoms are known, and it implies a magnetic field approaching 1015 gauss. deformed into long cylinders thinner than the quantum-rela- More thorough tests of the magnetar model would require a tivistic wavelength of an electron [see box on opposite page]. All second giant flare. Luckily, the heavens soon complied. In the ear- these strange phenomena have observable effects on magnetars. ly morning of August 27, 1998, some 19 years after the giant flare Because this physics was so exotic, the theory attracted few re- that began SGR astronomy was observed, an even more intense searchers at the time. wave of gamma rays and x-rays reached Earth from the depths of space. It drove detectors on seven scientific spacecraft to their Zapped Again maximum or off scale. One interplanetary probe, NASA’s Comet AS THESE THEORETICAL developments were slowly un- Rendezvous Asteroid Flyby, was forced into a protective shut- folding, observers were still struggling to see the objects that down mode. The gamma rays hit Earth on its nightside, with the were the sources of the bursts. The first opportunity came when source in the zenith over the mid-Pacific Ocean. NASA’s orbiting Compton Gamma Ray Observatory recorded Fortuitously, in those early morning hours electrical engineer a burst of gamma rays late one evening in October 1993. This Umran S. Inan and his colleagues from Stanford University were was the break Kouveliotou had been looking for when she gathering data on the propagation of very low frequency radio joined the Compton team in Huntsville. The instrument that reg- waves around Earth. At 3:22 A.M. PDT, they noticed an abrupt istered the burst could determine its position only to within a change in the ionized upper atmosphere. The inner edge of the fairly broad swath of sky. Kouveliotou turned for help to the ionosphere plunged down from 85 to 60 kilometers for five min- Japanese ASCA satellite. Toshio Murakami of the Institute of utes. It was astonishing. This effect on our planet was caused by Space and Astronautical Science in Japan and his collaborators a neutron star far across the galaxy, 20,000 light-years away. soon found an x-ray source from the same swath of sky. The source held steady, then gave off another burst—proving beyond Another Magneto Marvel all doubt that it was an SGR. The same object had first been seen THE AUGUST 27 FLARE was almost a carbon copy of the in 1979 and, based on its approximate celestial coordinates, was March 1979 event. Intrinsically, it was only one tenth as pow- identified as SGR 1806–20. Now its position was fixed much erful, but because the source was closer to Earth it remains the more precisely, and it could be monitored across the electro- most intense burst of gamma rays from beyond our solar system magnetic spectrum. ever detected. The last few hundred seconds of the flare showed The next leap forward came in 1995, when NASA launched conspicuous pulsations, with a 5.16-second period. Kouveliotou HOW MAGNETAR BURSTS HAPPEN

THE MAGNETIC FIELD OF THE STAR is so strong that the rigid crust sometimes breaks and crumbles, releasing a huge surge of energy.

Most of the time the At some point the solid crust This “starquake” creates The fireball cools by 1magnetar is quiet. 2is stressed beyond its limit. 3a surging electric current, 4 releasing x-rays from But magnetic stresses are It fractures, probably into many which decays and leaves behind its surface. It evaporates slowly building up. small pieces. a hot fireball. in minutes or less. DON DIXON

40 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. and her team measured the spin-down rate of the star with RXTE; sure enough, it was slowing down at a rate comparable EXTREME MAGNETISM to that of SGR 1806–20, implying a similarly strong magnetic MAGNETAR FIELDS wreak havoc with radiation and matter. field. Another SGR was placed into the magnetar hall of fame. The precise localizations of SGRs in x-rays have allowed VACUUM BIREFRINGENCE Polarized light waves (orange) change speed and them to be studied using radio and infrared telescopes (though hence wavelength when they enter a very strong not in visible light, which is blocked by interstellar dust). This magnetic field (black lines). work has been pioneered by many astronomers, notably Dale Frail of the National Radio Astronomy Observatory and Shri PHOTON SPLITTING Kulkarni of the California Institute of Technology. Other ob- In a related effect, x-rays freely split in two or merge together. This process is important servations have shown that all four confirmed SGRs continue to in fields stronger than 1014 gauss. release energy, albeit faintly, even between outbursts. “Faintly” is a relative term: this x-ray glow represents 10 to 100 times as SCATTERING SUPPRESSION A light wave can glide past an electron (black much power as the sun radiates in visible light. circle) with little hindrance if the field prevents By now one can say that magnetar magnetic fields are bet- the electron from vibrating with the wave. ter measured than pulsar magnetic fields. In isolated pulsars, almost the only evidence for magnetic fields as strong as 1012 DISTORTION OF ATOMS 9 gauss comes from their measured spin-down. In contrast, the Fields above 10 gauss squeeze electron orbitals into cigar shapes. In a 1014-gauss field, combination of rapid spin-down and bright x-ray flares provides a hydrogen atom becomes 200 times narrower. several independent arguments for 1014- to 1015-gauss fields in magnetars. As this article goes to press, Alaa Ibrahim of the NASA Goddard Space Flight Center and his collaborators have pears that magnetars can change their clothes. They can remain reported yet another line of evidence for strong magnetic fields quiescent for years, even decades, before undergoing sudden pe- in magnetars: x-ray spectral lines that seem to be generated by riods of extreme activity. Some astronomers argue that AXPs protons gyrating in a 1015-gauss field. are younger on average than SGRs, but this is still a matter of One intriguing question is whether magnetars are related to debate. If both SGRs and AXPs are magnetars, then magnetars cosmic phenomena besides SGRs. The shortest-duration gam- plausibly constitute a substantial fraction of all neutron stars. ma-ray bursts, for example, have yet to be convincingly ex- The story of magnetars is a sobering reminder of how much plained, and at least a handful of them could be flares from mag- we have yet to understand about our universe. Thus far, we have netars in other galaxies. If seen from a great distance, even a gi- discerned at most a dozen magnetars among the countless stars. ant flare would be near the limit of telescope sensitivity. Only They reveal themselves for a split second, in light that only the the brief, hard, intense pulse of gamma rays at the onset of the most sophisticated telescopes can detect. Within 10,000 years, flare would be detected, so telescopes would register it as a GRB. their magnetic fields freeze and they stop emitting bright x-rays. Thompson and Duncan suggested in the mid-1990s that So those dozen magnetars betray the presence of more than a magnetars might also explain anomalous x-ray pulsars, a class million, and perhaps as many as 100 million, other objects—old of objects that resemble SGRs in many ways. The one difficulty magnetars that long ago went dark. Dim and dead, these strange with this idea was that AXPs had not been observed to burst. worlds wander through interstellar space. What other phenom- Recently, however, Victoria M. Kaspi and Fotis P. Gavriil of ena, so rare and fleeting that we have not recognized them, lurk McGill University and Peter M. Woods of the National Space out there? and Technology Center in Huntsville detected bursts from two of the seven known AXPs. One of these objects is associated MORE TO EXPLORE with a young supernova remnant in the constellation Cassiopeia. Formation of Very Strongly Magnetized Neutron Stars: Implications for Another AXP in Cassiopeia is the first magnetar candidate Gamma-Ray Bursts. Robert C. Duncan and Christopher Thompson in Astronomical Journal, Vol. 392, No. 1, pages L9–L13; June 10, 1992. to have been detected in visible light. Ferdi Hulleman and Available at makeashorterlink.com/?B16A425A2 Marten van Kerkwijk of Utrecht University in the Netherlands, An X-ray Pulsar with a Superstrong Magnetic Field in the Soft Gamma- working with Kulkarni, spotted it three years ago, and Brian Ray Repeater SGR1806–20. C. Kouveliotou, S. Dieters, T. Strohmayer, J. Von Paradijs, G. J. Fishman, C. A. Meegan, K. Hurley, J. Kommers, I. Smith, Kern and Christopher Martin of Caltech have since monitored D. Frail and T. Murakami in Nature, Vol. 393, pages 235–237; May 21, 1998. its brightness in visible light. Though exceedingly faint, the AXP The Life of a Neutron Star. Joshua N. Winn in Sky & Telescope, Vol. 98, fades in and out with the x-ray period of the neutron star. These No. 1, pages 30–38; July 1999. observations lend support to the idea that it is indeed a magne- Physics in Ultra-strong Magnetic Fields. Robert C. Duncan. tar. The main alternative—that AXPs are ordinary neutron stars Fifth Huntsville Gamma-Ray Burst Symposium, February 23, 2002. Available at arXiv.org/abs/astro-ph/0002442 surrounded by disks of matter—predicts too much visible and Flash! The Hunt for the Biggest Explosions in the Universe. infrared emission with too little pulsation. Govert Schilling. Cambridge University Press, 2002. In view of these recent discoveries, and the apparent silence More information can be found at Robert C. Duncan’s Web site:

BRYAN CHRISTIE DESIGN of the Large Magellanic Cloud burster for nearly 20 years, it ap- solomon.as.utexas.edu/magnetar.html

www.sciam.com SCIENTIFIC AMERICAN 41 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. New research addresses the wrenching question left when someone ends his or her own life

WHYThe neuroscience ??? of suicide

By Carol Ezzell MATT MAHURIN

www.sciam.com SCIENTIFIC AMERICAN 45 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. In 1994, two days after returning from a happy family vacation, my 57-year-old mother put the muzzle of a handgun to her left breast and fired, drilling a neat and lethal hole through her heart—and, metaphorically, through our family’s as well. It was around midnight on a Saturday havioral tip-offs and are also exploring night in July, the time of year, I was later clues to anatomical and chemical differ- surprised to learn, that has the highest in- ences between the brains of suicides and cidence of suicide in the Northern Hemi- of those who die of other causes. If such sphere. My stepfather was at home but changes could be detected in medical didn’t hear the single shot because he was imaging scans or through blood tests, taking a shower in a bathroom at the oth- doctors might one day be able to identify er end of the house. When he returned to those at highest risk of dying by suicide— their bedroom, she was crumpled on the and therefore attempt to prevent the carpet in her pajamas, almost gone. She tragedy from occurring. Sadly, that goal is SUICIDE IS THE 11TH tried to say something to him before she not immediately in sight: many who have LEADING CAUSE OF died, but he couldn’t make out what it suicidal tendencies still end up taking their DEATH IN THE U.S., was. The emergency medical technicians own lives, despite intensive intervention. arrived to find a patient, but not the one ACCOUNTING FOR they expected: my stepfather nearly died My Mother’s Legacy 1.2 PERCENT OF ALL FATALITIES. himself that night after hyperventilating THE QUESTION of what drove my from the shock, which all but over- mother to her desperate act that humid whelmed lungs already compromised by night nearly nine years ago is the second A PERSON DIES BY SUICIDE emphysema. most difficult thing I live with. Scarcely Through it all, I was asleep in my a day has gone by that I haven’t been ROUGHLY EVERY 18 apartment 200 miles away. I was awak- pierced by the anguish of wanting to MINUTES IN THE U.S. ened at 2 A.M.by a call from my building’s know exactly what prompted her suicide SOMEONE ATTEMPTS SUICIDE front desk, telling me that my sister-in- on that particular night as well as the EVERY MINUTE. law was downstairs and wanted to come crushing guilt over what I could have up. My first words to her when I opened done—should have done, would have my door were, “It’s Mother, isn’t it?” done—to stop her. The hardest thing I Our family has too much company in have to live with is the realization that I FOUR MALES DIE BYSUICIDEFOR suffering the agony of having a loved one will never know the answer for sure. EVERY FEMALE, BUT AT LEAST die by suicide: annually, 30,000 people in In the future, some parts of her story TWICEASMANY WOMEN the U.S. take their own lives. That is rough- should become less mysterious, because ly half again the number who died of AIDS researchers are studying those very issues. AS MEN ATTEMPT SUICIDE. last year. Why do they do it? One age-old question, whether a tenden- Like an estimated 60 to 90 percent of cy to commit suicide is inborn or the re- U.S. suicides, my mother had a mental ill- sult of an accumulation of bad experi- APPROXIMATELY ness. In her case, it was manic-depression, ences, is at least closer to resolution. also called bipolar disorder. Unless they Although the nature-versus-nurture 80 AMERICANS TAKE are taking—and responding well to—the debate still rages in some psychiatric cir- THEIR OWN LIVES EVERY DAY. appropriate medication, manic-depres- cles, most researchers who study suicide sives oscillate between troughs of despair fall somewhere in the middle. “You need and peaks of elation or agitation. Most several things to go wrong at once,” ex- THE SUICIDE RATE FOR who end their lives have a history of de- plains Victoria Arango of the New York WHITE MALES pression or manic-depression, but people State Psychiatric Institute, which is affili- with severe depression differ in their ated with Columbia-Presbyterian Medical AGED 15 TO 24 propensity for suicide. Center. “I’m not saying that suicide is HAS TRIPLED SINCE 1950. Scientists have begun uncovering be- purely biological, but it starts with having

CHANGES IN THE ORBITAL IN PEOPLE WHO DIE BY SUICIDE, anatomical and chemical changes occur in two brain regions: PREFRONTAL CORTEX the orbital prefrontal cortex, which lies just above the eyes, and the dorsal raphe nucleus of the brain stem. The alterations are evidence of a reduced ability to make and use serotonin, a Slices from the brain of a suicide key neurotransmitter known to be lacking in the brains of impulsive people and in those victim contain fewer neurons in a suffering from depression. Neurons in the dorsal raphe nucleus produce serotonin; they have subsection (circled) of the orbital long projections (blue arrow) that carry the neurotransmitter to the orbital prefrontal cortex. prefrontal cortex. In suicide victims, the dorsal raphe nucleus sends less than normal amounts of serotonin to the orbital prefrontal cortex. —C.E.

SINGLE HEMISPHERE OF BRAIN Plane of sectioning

Throughout the cortex, serotonin transporters (gold) absorb serotonin. In the marked subsection, the number of these transporters is reduced.

Orbital prefrontal cortex Plane of sectioning Dorsal raphe

) nucleus brain diagram

); REPRODUCED WITH PERMISSION FROM The analyzed area also exhibits more binding of serotonin ); CLEO VILETT ( (orange) per neuron. Together CHANGES IN THE DORSAL RAPHE NUCLEUS brain slices ( the analyses indicate that the Neurons in the dorsal raphe nucleus of the brain stem of someone who died by suicide brain tried to make the most of contain more of the enzyme that synthesizes serotonin (dark staining) than the the serotonin it had. corresponding brain region of someone who died of another cause. The difference

neuron micrographs indicates that the brains of suicides are attempting to produce more serotonin.

SUICIDE VICTIM CONTROL VOL. 46, NO. 4; 1999 ( New York State Psychiatric Institute BIOLOGICAL PSYCHIATRY, VICTORIA ARANGO ET AL.

www.sciam.com SCIENTIFIC AMERICAN 47 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. BETWEEN 1980 AND 1996 an underlying biological risk.” Life expe- sion on a very bad day. So Arango and THE SUICIDE RATE FOR rience, acute stress and psychological fac- Mann search in these brains for clues to FRICAN MERICAN tors each play a part, she asserts. At the the biological basis for that impulsivity. A -A root of the mystery of suicide, however, One focus is on differences in the avail- MALES AGED 15 TO 19 lies a nervous system whose lines of com- ability of the brain chemical serotonin— INCREASED 105 PERCENT. munication have become tangled into un- previous research on the basis of impul- bearably painful knots. sivity has indicated a dearth of it. Arango and her Columbia colleague Serotonin is a neurotransmitter, one J. John Mann are leading the effort to of the molecules that jumps the tiny gaps UICIDE IS THE S pick apart those knots and discern the known as synapses between neurons to THIRD-RANKING neuropathology of suicide. They have as- relay a signal from one such brain cell to CAUSE OF DEATH FOR sembled what is generally acknowledged another. Tiny membranous bubbles called TEENS AGED 10 TO 19. to be the country’s best collection of brain vesicles erupt from each signal-sending, specimens from suicide victims. Twenty- or presynaptic, neuron, releasing sero- five deep freezers in their laboratories tonin into the synapse. Receptors on the hold a total of 200 such brains, which the receiving, or postsynaptic, neurons bind WHITE MEN 85 AND researchers are examining for neuroana- to the neurotransmitter and register bio- OLDER DIE BYSUICIDE tomical, chemical or genetic alterations chemical changes in the cell that can that might be unique to those compelled change its ability to respond to other stim- AT SIXTIMES THE OVERALL to end their lives. Each brain is accompa- uli or to turn genes on or off. After a short NATIONAL RATE. nied by a “psychological autopsy,” a com- while, the presynaptic cells reabsorb the pendium of interviews with family mem- serotonin using molecular sponges termed bers and intimates probing the deceased’s serotonin transporters. SUICIDE RATES FOR state of mind and behavior leading up to Serotonin somehow exerts a calming his or her final act. “We try to get a com- influence on the mind. Prozac and similar WOMEN PEAK BETWEEN plete picture,” Mann says, “and come up antidepressant drugs work by binding to THE AGES OF 45 AND 54 AND with an aggregate explanation for that serotonin transporters and preventing SURGE AGAIN AFTER AGE 85. person.” A suicide brain is matched against presynaptic neurons from soaking up the a control brain from a person of the same secreted serotonin too quickly, allowing sex without a psychiatric disorder who it to linger a bit longer in the synapse and died at approximately the same age of a continue to transmit its soothing effect. ALCOHOLISM IS A FACTOR cause other than suicide. IN ROUGHLY 30 PERCENT OF ALL Contained within the three-pound Traces of Pain COMPLETED SUICIDES. gelatinous mass of the human brain are MORE THAN two decades of reports the cells and molecules that were inextri- have linked low serotonin levels in the cably linked to what that person once brain to depression, aggressive behavior thought—and, indeed, once was. Mann’s and a tendency toward impulsiveness, but APPROXIMATELY 7 PERCENT OF and Arango’s research concentrates in part the evidence has been particularly con- PEOPLE WITH on the prefrontal cortex, the portion of the fusing with regard to suicide. A number ALCOHOL DEPENDENCE brain encased in the bone of the forehead. of studies have found reductions in sero- The prefrontal cortex is the seat of the so- tonin in the brains of suicides, whereas WILL DIE BYSUICIDE. called executive functions of the brain, in- others have not. Some have observed a cluding the internal censor that keeps in- lack of serotonin in one part of the brain dividuals from blurting out what they re- but not elsewhere. Still others have de- EIGHTY-THREE PERCENT OF ally think in awkward social situations or scribed increases in the number of recep- GUN-RELATED DEATHS acting on potentially dangerous impulses. tors for serotonin or deficits in the chain The impulse-dampening role played of chemical events that convey the sero- IN THE HOME ARE THE RESULT by the prefrontal cortex particularly in- tonin signal from those receptors to the OF SUICIDE. terests Mann and Arango. Scientists have inside of a neuron. looked to impulsivity as a predictor for Despite the inconsistencies, the bulk suicide for decades. Although some peo- of evidence points strongly to a problem DEATH BY FIREARMS IS THE ple plan their deaths carefully—leaving in the brains of suicides involving the notes, wills and even funeral plans—for serotonin system. That line of thinking FASTEST-GROWING many, including my mother, suicide ap- has been bolstered by the recent findings METHOD OF SUICIDE. pears to be spontaneous: a very bad deci- of Arango and Mann.

“Lithium ... is the lightest of the solid elements, and it is perhaps not surprising that it should in consequence possess certain modest magical qualities.” —G. P. Hartigan, psychiatrist

“Only crazy people take lithium!” my mother shouted during one of our many arguments over her not receiving the best treatment for her manic-depression. She accused me and my stepfather of wanting to medicate her so she would “just shut LITHIUM is the up.” To be honest, she was partially right: it is very trying to be lightest of the solid around someone in the grip of a mania, which often brings on elements and, in its incessant, stream-of-consciousness talking. pure form, floats Many people find lithium—which generally comes in (left). When compounded in pill capsules of lithium carbonate or lithium citrate—difficult to form as lithium take. It can cause hand tremors, constant thirst, frequent carbonate or lithium urination, weight gain, lethargy, reduced muscle coordination, citrate (above), blurred thinking and short-term memory deficits. People on it it can be taken to must also have its concentration in their blood assessed stabilize moods. regularly to ensure that it is within the therapeutic range: the drug is usually ineffective below 0.6 millimole per liter of blood serum and can cause life-threatening toxic reactions if the level becomes higher than two millimoles per liter. Lithium is used routinely to even out the extreme mood swings of patients with manic-depressive illness, or bipolar disorder. Increasingly, however, it is also offered to people with depression. But a growing body of evidence indicates that this Scott and Marie Pope of the University of Glasgow reported that compound can literally keep people who are at risk of suicide half of a group of 98 patients who were taking a mood- alive. In 1998 lithium pioneer Mogens Schou of the Psychiatric stabilizing drug such as lithium failed to stick with their drug Hospital in Risskov, Denmark, pulled together the results of regimen. Yet, the researchers noted, just 1 percent of scientific various studies of lithium as a suicide preventive and observed publications on the subject of mood stabilizers looked at why that people not taking the drug were three to 17 times as likely patients did not take their lithium as prescribed. to end their own lives as depressed people who took the J. John Mann of the New York State Psychiatric Institute medication. Likewise, Schou determined that lithium reduced says that a major factor in noncompliance is the human desire

) suicide attempts by a factor of between six and 15. not to want to think of oneself as ill. “There’s a natural reluctance pill How does it exert its salutary effects? Despite a number of to take any medicine long-term,” Mann explains. “When a person tantalizing leads, researchers are still not certain. “It’s hard to is depressed, they have a problem imagining ever getting better. say at this time,” says Ghanshyam N. Pandey of the University When they’re well, they can’t imagine getting sick again.” of Illinois. “There are so many modes of action.” Lithium is The side effects of lithium also play a role. Kay Redfield thought to affect tiny ports called ion channels on the surfaces Jamison, a psychiatrist at Johns Hopkins University who of nerve cells, or neurons. As they open and close, ion channels studies manic-depression and suicide—and who is a manic- admit or bar charged atoms that determine the electrical depressive herself—has found that the most common reasons potential within the cells, thereby dictating their activity and patients stop taking the drug are cognitive side effects, weight ); CUSTOM MEDICAL STOCK PHOTO ( ability to communicate with other neurons. Scientists posit that gain and impaired coordination. In her moving memoir, An the drug stabilizes the excitability of the neurons by influencing Unquiet Mind, she recounts her own struggle to come to terms container the ion channels or by skewing the chain reaction of with the fact that she will probably be coping with lithium’s side biochemical events that occur within an excited cell. effects for the rest of her life. Perhaps if my mother had lived to A drug only works, though, if someone takes it properly. In read it, she would have been heartened by Jamison’s example the May 2002 issue of the Journal of Clinical Psychiatry, Jan and motivated to begin lithium therapy. —C.E. THOMAS SIELNACHT (

www.sciam.com SCIENTIFIC AMERICAN 49 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. they can compile an overall model of how Ghanshyam N. Pandey of the Univer- SUICIDES OUTNUMBER those abnormalities might work in concert sity of Illinois agrees that the brain’s sero- HOMICIDES TWO TO ONE to affect a complex behavior. tonin system is key to understanding sui- EVERY YEAR IN THE U.S. At a conference of the American Col- cide. “There is a lot of evidence to suggest lege of Neuropsychopharmacology in serotonin defects in suicide, but these de- 2001, Arango reported that the brains of fects do not exist in isolation but in con- people who were depressed and died by cert with other deficits,” he says. “The SUICIDE ACCOUNTS FOR NEARLY suicide contained fewer neurons in the whole system appears to be altered.” 57 PERCENT OF ALL orbital prefrontal cortex, a patch of brain The serotonin hypothesis does not FIREARM DEATHS IN THE U.S.; just above each eye. What is more, in sui- rule out important contributions by oth- 60 PERCENT OF ALL SUICIDES cide brains, that area had one third the er neurotransmitters, however. Serotonin number of presynaptic serotonin trans- is only one molecule in the intricate bio- INVOLVE FIREARMS. porters that control brains had but rough- chemical network named the hypothala- ly 30 percent more postsynaptic sero- mic-pituitary-adrenal (HPA) axis, in tonin receptors. which the hypothalamus and pituitary Together the results suggest that the glands in the brain communicate with the brains of suicides are trying to make the adrenal glands atop the kidneys. The most of every molecule of serotonin they HPA is responsible for the so-called fight- have, by increasing the molecular equip- or-flight response exemplified by the rac- ment for sensing the neurotransmitter ing heartbeat and sweaty palms you get while decreasing the number of trans- after a close scrape while driving, say. In porters that absorb it back again. “We be- particular, corticotrophin-releasing fac- lieve there is a deficiency in the serotoner- tor, which the hypothalamus releases in gic system in people who commit sui- times of stress, causes the anterior pitu- cide,” Arango concludes. “They can be so itary to make adrenocorticotropic hor- sick Prozac can’t help them.” Inhibiting mone, which in turn causes the adrenal In a second-floor laboratory at the up- the reuptake of serotonin isn’t always cortex to produce glucocorticoids such as per tip of Manhattan, Arango’s techni- enough to prevent suicide: it wasn’t for cortisol. Cortisol prepares the body for cian leans into an open freezer to use a my mother, who died despite taking 40 stress by raising blood sugar concentra- machine called a microtome to pare a milligrams of Prozac a day. tions, increasing heart rate and inhibiting feather-light slice from a frozen brain do- Mann and his colleagues are now try- the overreaction of the immune response. nated by grieving relatives anxious to help ing to devise a positron emission tomog- Serotonin fits into the HPA because it science address the mystery of suicide. Us- raphy (PET) test that might one day aid modulates the threshold of stimulation. ing a chilled brush, she delicately coaxes doctors in determining which among Researchers such as Charles B. Nemeroff the rime of icy tissue onto a glass slide the their depressed patients have the most of the Emory University School of Medi- size of a snapshot. With the body heat skewed serotonin circuitry—and are there- cine and his colleagues are finding that ex- from her own gloved hands, she then fore at highest risk of suicide. PET scans tremely adverse early life experiences, melts the brain sliver onto the glass; ob- mirror brain activity by monitoring which such as child abuse, can throw the HPA serving the process is reminiscent of brain regions consume the most blood axis off kilter, literally leaving biochemi- watching bright sunlight on a frigid win- glucose; administering drugs, such as fen- cal imprints on the brain that make it vul- ter day dissolve frost on a window. fluramine, that cause the release of sero- nerable to depression as a result of over- The scientists working with the Co- tonin can help scientists zero in on active reacting to stress later on. lumbia collection divide the brains into brain areas using serotonin. In 1995 Pandey’s group reported in- left and right hemispheres and then care- In the January Archives of General dications that the abnormalities in sero- fully section each hemisphere into 10 or Psychiatry, Mann and his co-workers re- tonin circuitry present in those at risk for 12 blocks from front to back. Once ported a relation between activity in the suicide could be detectable using a rela- frozen and put through the microtome, prefrontal cortex of people who had at- tively simple blood test. When he and his every block yields roughly 160 slices that tempted suicide and the potential deadli- co-workers compared the number of are thinner than a human hair. ness of the attempt. Those who had used serotonin receptors on platelets (clotting The chief benefit of this approach is the most dangerous means—for example, cells) in the blood of suicidal people with that Arango’s and Mann’s groups can per- by taking the most pills or jumping from those of nonsuicidal people, they ob- form several different biochemical tests on the highest point—had the least serotonin- served that individuals considering sui- the same brain slice and know the exact based activity in the prefrontal cortex. cide had many more serotonin receptors. anatomical locations of the variations they “The more lethal the suicide attempt, the (Platelets just happen to have receptors find. By reassembling the slices virtually, bigger the abnormality,” Mann observes. for serotonin, although it is unclear why.)

50 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. Pandey says that his group concluded that the boost in receptors reﬂects a similar increase in the suicide-prone brains— a vain attempt to garner as much serotonin as possible. To prove the link, Pan- dey would like to determine whether the association holds up in people who go on to take their own lives. “We want to know if platelets can be used as markers for identifying suicidal patients,” Pandey says. “We are making progress, but it’s slow.” A Curse of Generations UNTIL RESEARCHERS can develop tests to forecast those at highest risk for suicide, doctors might concentrate their efforts on the biological relatives of suicide victims. In the September 2002 issue of Archives of General Psychiatry, Mann, David A. Brent of the Western Psychiatric Institute and Clinic in Pittsburgh and their colleagues reported that the offspring of suicide attempters have six times the risk of people whose parents never attempted suicide. The link appears in part to be genetic, but efforts to pin down a predis- posing gene or genes have not yet yielded any easy answers. In studies in the early 1990s Alec Roy of the Department of Veterans Affairs Medical Center in East Orange, N.J., observed that 13 percent of the identical twins of people who died by suicide also eventually took their own lives, whereas only 0.7 percent of frater- nal twins traveled the same path as their suicidal siblings. These statistics serve as warnings to me and to others with biological ties to suicide. In a small jar in my bedroom I keep a bullet from the same box that contained the one that killed my mother. The police took the gun after her death, and I myself threw away the remaining bullets while cleaning out her bedroom closet. But I like to think that I hold on to that single, cold pellet of metal as a reminder of how tenuous life is and how one im- MORE TO EXPLORE pulsive act can have immense and rip- Night Falls Fast: Understanding Suicide. Kay Redfield Jamison. Vintage Books, 2000. pling consequences. Perhaps someday science will better understand the basis for Reducing Suicide: A National Imperative. Institute of Medicine. Edited by Sarah K. Goldsmith, Terry C. Pellmar, Arthur M. Kleinman and William E. Bunney. National Academies Press, 2002. such harrowing acts so that families like Information and education materials on preventing suicide can be obtained from the National mine will be spared. Mental Health Association (www.nmha.org), the American Foundation for Suicide Prevention (www.afsp.org) and the American Association of Suicidology (www.suicidology.org). The groups also have support materials for the survivors of loved ones who died by suicide. MATT MAHURIN Carol Ezzell is a staff editor and writer.

volution is an immensely powerful including several that were hailed as seminal in creative process. From the intricate their respective fields when they were first an- biochemistry of individual cells to the nounced [see box on page 57]. Six of these 15 ex- elaborate structure of the human isting inventions were patented after January 2000 brain, it has produced wonders of by major research institutions, which indicates that Eunimaginable complexity. Evolution achieves these they represent current frontiers of research in do- feats with a few simple processes—mutation, sex- mains of scientific and practical importance. Some ual recombination and natural selection—which it of the automatically produced inventions infringe iterates for many generations. Now computer pro- squarely on the exact claims of the previously grammers are harnessing software versions of these patented inventions. Others same processes to achieve machine intelligence. represent new inventions Called genetic programming, this technique has de- by duplicating the signed computer programs and electronic circuits functionality of the that perform specified functions. earlier device in a In the field of electronics, genetic programming novel way. One has duplicated 15 previously patented inventions, of these inventions is

Illustrations by Bryan Christie Design

Computer programs that function via Darwinian evolution are creating inventions that are novel and useful enough to be patented

a clear improvement over its predecessor. thinking. Evolution does not know any- population, and it applies genetic opera- Genetic programming has also classi- thing about the underlying math; it sim- tions to the surviving functions to create fied protein sequences and produced hu- ply tries to produce a sequence of im- offspring. The most important genetic op- man-competitive results in a variety of ar- proved results. Thus, we frequently see eration is sexual reproduction, or cross- eas, such as the design of antennas, math- creative things come out of the evolu- over, which mates pairs of the better or- ematical algorithms and general-purpose tionary process that would never occur to ganisms to sire offspring composed of ge- controllers [see box on page 59]. We have human designers. netic material from the two parents [see recently filed for a patent for a genetical- top illustration on opposite page]. For in- ly evolved general-purpose controller that Out of the Primordial Ooze stance, mating the functions (a + 1) – 2 is superior to mathematically derived con- WHATEVER THE FIELD of endeavor, and 1 + (a × a) might result in the (a + 1) trollers commonly used in industry. genetic programming begins with a pri- part of the first function substituting for The first practical commercial area mordial ooze of randomly generated trial one a of the second function, producing for genetic programming will probably “organisms” and a high-level description offspring 1 + ((a + 1) × a). Recombining be design. In essence, design is what en- of what function the organisms are meant the traits of two relatively fit organisms gineers do eight hours a day and is what to accomplish—the criteria for scoring in this fashion sometimes produces supe- evolution does. Design is especially well their fitness. As an example, consider a rior offspring. suited to genetic programming because it case in which the organisms are elemen- In addition to sexual reproduction, presents tough problems for which peo- tary mathematical functions and we are genetic programming copies about 9 per- ple seek solutions that are very good but endeavoring to find a function whose cent of the fittest individuals unaltered not mathematically perfect. Generally graph matches a given curve. The organ- into the next generation, which generally there are complex trade-offs between isms in this case are composed of numer- ensures that the best organisms in each competing considerations, and the best ical constants and primitive operations generation are at least as fit as those of the balance among the various factors is dif- such as addition, subtraction, multiplica- previous generation. Finally, about 1 per- ficult to foresee. Finally, design usually tion and division. The fitness of a function cent of the programs undergo mutation— involves discovering topological arrange- is determined by how closely its graph fol- for instance, a + 2 might mutate into (3 × ments of things (as opposed to merely op- lows the target curve. a) + 2—in the hope that a random modi- timizing a set of numbers), a task that ge- The genetic program evaluates the fit- fication of a relatively fit program will netic programming is very good at. ness of each mathematical function in the lead to improvement. Human engineers tend to look at prob- population. The initial, randomly created These genetic operations progressive- lems in particular ways, often based on functions will, of course, match the target ly produce an improved population of ideal mathematical models. Genetic pro- curve quite poorly, but some will be bet- mathematical functions. The exploitation gramming offers the advantage of not be- ter than others. The genetic program of small differences in fitness yields major ing channeled down narrow paths of tends to discard the worst functions in the improvements over many generations in much the same way that a small interest rate yields large growth when compound- Overview/Darwinian Invention ed over decades. ■ Genetic programming harnesses a computerized version of evolution to create One can visualize the evolutionary new inventions. Starting from thousands of randomly generated test objects, process as being a search in the space of the method selects the better individuals and applies processes such as all possible organisms. The crossover op- mutation and sexual recombination to generate successive generations. eration conducts the most creative kind ■ Over the course of dozens of generations, the population of individuals of search, which is why we use it to pro- gradually fulfills the target criteria to a greater degree. At the end of the run, duce around 90 percent of the offspring the best individual is harvested as the solution to the posed problem. in each generation [see bottom illustra- ■ In electronics, the technique has reproduced patented inventions, some of tion on opposite page]. Mutation, in con- which lie at the forefront of current research and development. Other trast, tends to conduct a local search for inventions include antennas, computer algorithms for recognizing proteins, advantage near the existing good indi- and general-purpose controllers. Some of these computer-evolved inventions viduals. We believe that too great a mu- should themselves be patentable. tation rate results in less efficient evolu- ■ By the end of the decade, we envision that increased computer power will tion except in the case of particularly sim- enable genetic programming to be used as a routine desktop invention machine ple problems. competing on equal terms with human inventors. A more sophisticated example than a mathematical function is the evolution of

54 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. a computer program, such as one em- UNNATURAL SELECTION ploying iterations and memory for clas- sifying protein sequences. In this case, ge- Evolutionary Processes netic programming can carry out ana- THREE PROCESSES propagate “organisms” (represented here by colored disks) from logues of the biological processes of gene one generation to the next in a genetic programming run. Some of the better duplication and gene deletion, to create or organisms are copied unaltered. Others are paired up for sexual reproduction, or delete subroutines, iterations, loops and crossover, in which parts are swapped between the organisms to produce offspring. recursions in the evolving population of A small percentage are changed randomly by mutation. Organisms not chosen for programs. The evolutionary process itself propagation become extinct. The crossover operation is applied more frequently than determines the character and content of copying and mutation because of its ability to bring together new combinations of the computer program needed to solve favorable properties in individual organisms. the problem. Extinction CopyingCrossover Crossover A low-pass filter circuit provides a good illustration of how genetic programming designs analog electronic circuits. A low-pass filter is used in a hi-fi system to send only the lowest frequencies to the woofer speaker. To create a low-pass filter by using genetic programming, the human user specifies which components are available for building the circuit (say, Mutation resistors, capacitors and inductors) and defines the fitness of each candidate cir- Crossover of Electronics cuit to be the degree to which it passes fre- ACTING ON electronic circuits, the crossover operation takes two circuits and swaps quencies up to 1,000 hertz at full power some of their components, producing two new circuits. while filtering out all higher frequencies. The circuits are generated in a way First-Generation Circuits Resistor that borrows mechanisms from developmental biology. Each circuit begins as an Capacitor elementary “embryo” consisting of a single wire running from the input to the output. The embryonic circuit grows by Inductor progressive application of circuit-constructing functions. Some of the circuit- constructing functions insert particular components. Others modify the pattern of connections between components: they might duplicate an existing wire or Second-Generation Circuits component in series or parallel, or they might create a connection from a particular point to a power supply, the ground Crossover versus Mutation or a distant point in the growing circuit. EVOLUTION ACTS like a search in the space of all possible organisms, Crossover This developmental process yields both Organism the circuit topology and the numerical represented here by the plane. component sizes. The system automati- Crossover searches this space cally synthesizes circuits without using creatively, occasionally any advanced know-how from the field combining disparate good of electrical engineering concerning cir- features, leaping to a new cuit synthesis. region of organism space where much fitter individuals Most of the initial population of Mutation rudimentary circuits generated random- reside (red arrows). Mutation, ly in this way will behave nothing like a in contrast, tends to find the low-pass filter. A few, however, will con- best organism that is “nearby” tain an inductor between the circuit’s in- (green arrows). put and output, thereby slightly imped- www.sciam.com SCIENTIFIC AMERICAN 55 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. EVOLVING A LOW-PASS FILTER

•1 •2 •3

Resistor Inductor Capacitor •4 •5 •6 TO EVOLVE a low-pass filter, which passes low frequencies and blocks high frequencies, the genetic program would begin with random circuits (1). Some would luckily have an inductor positioned to impede high frequencies or a capacitor positioned to drain off high frequencies. These circuits would combine by crossover (2) to produce rudimentary low-pass filter circuits (3). Further crossovers between these circuits (4) would produce a ladder low- pass filter (5). Mutations (6) would eliminate superfluous resistors and would fine-tune the values of the components. ing higher frequencies. Others will have The primitive ingredients used to cre- general-purpose controllers, which can a capacitor running from the input to the ate controllers automatically consist of be customized to a variety of speciﬁc ground, thereby slightly draining the differentiators, integrators and ampli- tasks—such as the control of a home fur- power of higher frequencies [see illustra- ﬁers. An example of a basic controller is nace, manufacturing processes in facto- tion above]. Such circuits will be selected a cruise control on a car, which must re- ries or the reading arm of a computer’s to mate more frequently than others, and duce fuel intake if the speed rises too high disk storage device. Small improvements eventually later generations will contain or increase it if the speed falls too low. A in the “tuning rules” used in customizing offspring incorporating both features. good controller will allow for the delayed a controller can result in large economic The crossover and mutation operations response to fuel changes and will contin- savings. acting on numerical expressions will ad- uously monitor how the speed is varying A commonplace controller is the PID just component values so that the cutoff to avoid excessive overshooting of the controller invented in 1939 by Albert Cal- frequency approaches the desired 1,000 target speed. Of great importance are lender and Allan Stevenson of Imperial Hz. Other crossovers and mutations will delete resistors that dissipate power. Ad- JOHN R. KOZA, MARTIN A. KEANE and MATTHEW J. STREETER work closely with one another ditional crossovers will double or triple studying genetic programming using a home-built, 1,000-Pentium parallel computer. Koza the inductor-capacitor combination, received his Ph.D. in computer science from the University of Michigan in 1972. He co-found- yielding the ladder structure patented in ed Scientific Games, Inc., in Atlanta in 1973, where he co-invented the rub-off instant lot- 1917 by George A. Campbell of AT&T. tery ticket used by state lotteries. In 1987 Koza invented genetic programming. He is cur- Other devices are designed with sim- rently consulting professor in the Stanford Biomedical Informatics program in the depart- THE AUTHORS ilar combinations of evolutionary and ment of medicine and consulting professor in the university’s department of electrical developmental processes. Antennas, for engineering. Keane received a Ph.D. in mathematics from Northwestern University in 1969. instance, are automatically designed with From 1976 to 1986 he was vice president for engineering at Bally Manufacturing Corpora- a “turtle” that deposits (or does not de- tion in Chicago. He is now chief scientist at Econometrics, Inc., also in Chicago. Streeter re- posit) metal on a plane as it moves and ceived a master’s degree from Worcester Polytechnic Institute in 2001. His primary research turns under the control of various oper- interest is applying genetic programming to problems of real-world scientific or practical ations (similar to those in the LOGO pro- importance. He works at Genetic Programming, Inc., in Los Altos, Calif., as a systems programming language). grammer and researcher.

Chemical Limited in Northwich, En- gies. If (as we expect) the patent is grant- Known as rapidly reconfigurable field- gland. PID controllers (the initials stand ed, we believe that it will be the first one programmable gate arrays, these chips for the controller’s proportional, inte- granted for an invention created by ge- consist of thousands of identical cells, each grative and derivative parts) are used in netic programming. of which can perform numerous different myriad applications. Our genetic pro- logical functions, depending on how it is grams have evolved two distinct im- Evolvable Hardware programmed. Sets of memory bits in the provements in this field. First, they have DURING THE EVOLUTIONARY pro- “basement” of the chip customize each developed a new set of tuning rules for cess, we must efficiently evaluate the fit- cell so that it performs a particular logical PID controllers. A relatively simple and ness of thousands or millions of offspring function. Other configuration bits pro- effective set of PID tuning rules has been in each generation. For electronic circuits, gram interconnection routes on the chip, in general use since 1942 and was im- we usually use standard circuit-simulator permitting many different ways of con- proved on in 1995; our rules outperform software to predict the behavior of each necting the cells to one another and to the the 1995 rules. Second, we evolved three circuit in the population. In an important chip’s input and output pins. The “per- new controller circuit topologies that emerging area of technology called evolv- sonality” of the chip (its logical functions also outperform PID controllers that use able hardware, however, microchips can and interconnections) can be changed dy- the old tuning rules. We have filed a be instantaneously configured to physi- namically in nanoseconds merely by patent application that covers both the cally implement each circuit of a genetic changing its configuration bits. new rules and the new controller topolo- programming run. These rapidly reconfigurable chips are Patented Inventions Re-created by Computer TO DATE, genetic programming has re-created 15 inventions that were previously patented by the inventors listed here. INVENTION YEAR INVENTOR INSTITUTION LADDER FILTER 1917 George A. Campbell AT&T, New York City CROSSOVER FILTER 1925 Otto Julius Zobel AT&T NEGATIVE FEEDBACK AMPLIFIER 1927 Harold S. Black AT&T ELLIPTIC FILTER 1934–36 Wilhelm Cauer University of Göttingen, Germany PID (proportional, integrative and 1939 Albert Callender and Imperial Chemical Limited, derivative) CONTROLLER Allan Stevenson Northwich, England SECOND-DERIVATIVE CONTROLLER 1942 Harry Jones Brown Instrument Company, Philadelphia DARLINGTON EMITTER-FOLLOWER SECTION 1953 Sidney Darlington Bell Telephone Laboratories, New York City PHILBRICK CIRCUIT 1956 George A. Philbrick George A. Philbrick Researches, Boston SORTING NETWORK 1962 Daniel G. O’Connor and General Precision, Los Angeles Raymond J. Nelson MIXED ANALOG-DIGITAL INTEGRATED CIRCUIT 2000 Turgut Sefket Aytur Lucent Technologies, Murray Hill, N.J. for producing variable capacitance VOLTAGE-CURRENT CONVERTER 2000 Akira Ikeuchi and Mitsumi Electric, Tokyo Naoshi Tokuda CUBIC FUNCTION GENERATOR 2000 Stefano Cipriani and Conexant Systems, Newport Beach, Calif. Anthony A. Takeshian LOW-VOLTAGE, HIGH-CURRENT TRANSISTOR 2001 Timothy Daun-Lindberg IBM, Armonk, N.Y. CIRCUIT for testing a voltage source and Michael Miller LOW-VOLTAGE BALUN CIRCUIT 2001 Sang Gug Lee Information and Communications University, Taejon, Korea

TUNABLE INTEGRATED ACTIVE FILTER 2001 Robert Irvine and Bernd Kolb Infineon Technologies, Munich, Germany

www.sciam.com SCIENTIFIC AMERICAN 57 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. sold by about a dozen companies, but human-competitive results listed in the We have built a Beowulf-style com- they are primarily of use for digital cir- box on the preceding page; however, all puter cluster consisting of 1,000 some- cuits. Commercially available analog six of the inventions patented after 2000 what outdated 350-megahertz Pentium chips are extremely limited in their abili- required more horsepower than that. computers [see “The Do-It-Yourself Su- ties. We used a reconfigurable digital chip Evolution in nature thrives when or- percomputer,” by William W. Hargrove, to create a sorting network with fewer ganisms are distributed in semi-isolated Forrest M. Hoffman and Thomas Sterling; steps than the originally patented version. subpopulations. The same seems to be Scientific American, August 2001]. true of genetic programming run on a For our most time-consuming problems, Run Times loosely connected network of computers. evaluation of the fitness of a single candi- NATURAL EVOLUTION has had bil- Each computer can perform the time- date individual takes about a minute of lions of years of “run time” to produce its consuming step of evaluating the fitness computer time. A run involving a popu- wonders. Artificial genetic programming of individuals in its subpopulation. Then, lation of 100,000 individuals for 100 gen- would not be of much use if it took as at the end of each generation, a small per- erations can be completed in about seven long. A genetic programming run typi- centage of individuals (selected based on days on our cluster. cally spawns a population of tens or hun- fitness) migrates to adjacent computers in The 1,000 computers together per- dreds of thousands of individuals that the network so that each semi-isolated form about 350 billion cycles a second. evolve over dozens or hundreds of gener- subpopulation gets the benefit of the evo- Although this amount of computer time ations. A weeklong run on a laptop com- lutionary improvement that has occurred may, at first blush, sound like a lot, it puter is sufficient to produce half of the elsewhere. pales in comparison to the amount of computation performed by the trillion cells of the human brain (each of which HUMAN VERSUS COMPUTER is thought to have about 10,000 connections and operate at a rate of 1,000 op- THE TWO CIRCUITS shown below are both cubic signal generators. The upper circuit is erations a second). a patented circuit designed by a human; the green and purple parts of the lower We expect that 50-gigahertz comput- circuit were evolved by genetic programming (the other parts are standard input and ers (performing 50 billion cycles a second) output stages). The evolved circuit performs with better accuracy than the human- will be commonly available toward the designed one, but how it functions is not understood. The evolved circuit is clearly end of this decade, putting the power to more complicated but also contains redundant parts, such as the purple transistor, evolve patent-worthy inventions using ge- that contribute nothing to its functioning. netic programming in the hands of anyone owning a moderately priced desktop Man-made circuit 2-volt supply Final voltage Input voltage workstation. We envision that genetic programming will be regularly used as an invention machine. Passing an Intelligence Test GENETIC PROGRAMMING is now routinely reproducing human inventions, just half a century after computer pioneer Alan M. Turing predicted that human-competitive machine intelligence would be achieved in about 50 years. Ground Voltage to current converter Transistor Current to Voltage source voltage converter During those 50 years, the two main aca- demically fashionable approaches taken 2-volt supply Evolved circuit by researchers striving to vindicate Tur- ing’s prediction have used logical deduction or databases containing accumulated human knowledge and expertise (so- called expert systems). Those two approaches roughly correspond to two broad methods outlined by Turing in 1950. The first (not surprising in light of Turing’s work in the 1930s on the logical foundations of computing) was the construction of programs designed to an-

58 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. More Human-Competitive Creations AS WELL AS re-creating patented inventions, genetic programming has generated these results that a human would be proud of.

SOCCER-PLAYING PROGRAM that ranked in the middle of the field of 34 human-written programs in the RoboCup 1998 competition REAL-TIME ANALOG CIRCUIT for time-optimal control of a robot FOUR DIFFERENT ALGORITHMS for identifying transmembrane segments of proteins DERIVING MOTIFS (highly conserved sequences of amino acids) to identify certain families of proteins ALGORITHMS FOR QUANTUM COMPUTERS that in some cases solve problems better than any previously published result NAND CIRCUIT for carrying out the NOT AND logical operation on two inputs ANALOG COMPUTATIONAL CIRCUITS for the square, cube, square root, cube root, logarithm and Gaussian functions DIGITAL-TO-ANALOG CONVERTER CIRCUIT ANALOG-TO-DIGITAL CONVERTER CIRCUIT

alyze situations and problems logically the computer-created duplicate would for, the criterion being the survival value.” and to respond accordingly. The second, also have satisfied the patent office. Turing did not specify how to conduct which Turing called a cultural search, ap- This intelligence test does not deal a “genetical or evolutionary search” to plied knowledge and expertise gathered with inconsequential chitchat or the play- achieve machine intelligence, but he did from experts. ing of a game. When an institution or in- point out that: The goal of artificial intelligence and dividual allocates time and money to in- machine learning is to get computers to vent something and to embark on the We cannot expect to find a good child- solve problems from a high-level state- time-consuming and expensive process of machine at the first attempt. One must ment of what needs to be done. Genetic obtaining a patent, it has made a judg- experiment with teaching one such programming is delivering human-comment that the work is of scientific or prac- machine and see how well it learns. petitive machine intelligence with a min- tical importance. Moreover, the patent One can then try another and see if it is imum of human involvement for each office requires that the proposed inven- better or worse. There is an obvious new problem and without using either tion be useful. Patented inventions repre- connection between this process and logical deduction or a database of human sent nontrivial work by exceptionally cre- evolution, by the identifications knowledge. ative humans. Turing also proposed a famous test Although some people may be sur- Structure of the child machine for machine intelligence. In one widely prised that routine human-competitive = Hereditary material used restatement of the Turing test, a machine intelligence has been achieved Changes of the child machine judge receives messages “over a wall” and with a nondeterministic method and with- = Mutations tries to decide whether the messages came out resorting to either logic or knowl- Natural selection from a human or a machine. We do not edge, Alan Turing would not be. In his = Judgment of the experimenter claim that genetic programming has 1950 paper, Turing also identified this achieved the kind of general imitation of third approach to machine intelligence: Genetic programming has in many human cognition associated with the Tur- “the genetical or evolutionary search by ways fulfilled the promise of Turing’s third ing test. But it has passed a test of cre- which a combination of genes is looked way to achieve machine intelligence. ativity and ingenuity that only a relatively small number of humans pass. The U.S. MORE TO EXPLORE patent office has been administering this Computing Machinery and Intelligence. Alan M. Turing in Mind, Vol. 59, No. 236, pages 433–460; test for more than 200 years. October 1950. Available at www.abelard.org/turpap/turpap.htm by permission of Oxford The patent office receives written de- University Press. Genetic Programming: On the Programming of Computers by Means of Natural Selection. scriptions of inventions and then judges John R. Koza. MIT Press, 1992. whether they are unobvious to a person Genetic Programming: The Movie. John R. Koza and James P. Rice. MIT Press, 1992. having ordinary skill in the relevant field. Genetic Programming III: Darwinian Invention and Problem Solving. John R. Koza, Forrest H Whenever an automated method dupli- Bennett III, David Andre and Martin A. Keane. Morgan Kaufmann, 1999. cates a previously patented human-de- Genetic Programming III: Videotape: Human-Competitive Machine Intelligence. John R. Koza, signed invention, the automated method Forrest H Bennett III, David Andre, Martin A. Keane and Scott Brave. Morgan Kaufmann, 1999. has passed the patent office’s intelligence Genetic Programming IV: Routine Human-Competitive Machine Intelligence. John R. Koza, Martin A. Keane, Matthew J. Streeter, William Mydlowec, Jessen Yu and Guido Lanza. test. The fact that the original, human-de- Kluwer Academic Publishers (in press). signed version satisfied the patent office’s More information can be obtained from Genetic Programming, Inc. (www.genetic-programming.com), criteria of patent-worthiness means that and the Genetic Programming Conference organization (www.genetic-programming.org)

www.sciam.com SCIENTIFIC AMERICAN 59 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. ExplainingFrogDeformities An eight-year investigation into the cause of a shocking increase in deformed amphibians has sorted out the roles of three prime suspects

ONE HOT SUMMER DAY in 1995 eight blamed the increase on the amphibians’ greater exposure to ul- middle school children planning a simple study of wetland traviolet radiation, on chemical contamination of water or on ecology began collecting leopard frogs from a small pond near a parasite epidemic. Not surprisingly, every time another re- Henderson, Minn. To their astonishment, one captured frog port appeared, media outlets touted the new view, thus pro- after another had five or more hind legs, some twisted in viding a misleading picture of the situation. It turns out that all macabre contortions. Of the 22 animals they caught that day, these factors probably operate to varying extents, each caus- half were severely deformed. A follow-up search by pollution- ing particular disfigurements, and that all three may at times control officials added to the gruesome inventory. Occasional act in concert. Moreover, all stem in part from human activi- frogs in the pond had no hind limbs at all or had mere nubbins ties such as habitat alteration. where legs should be; others had one or two legs sprouting Deformities undoubtedly impair amphibian survival and from the stomach. A few lacked an eye. most likely contribute to the dramatic declines in populations The story seized national media attention and raised many that have been recognized as a global concern since 1989 [see questions—among them, was this an isolated occurrence or “The Puzzle of Declining Amphibian Populations,” by Andrew one facet of a widespread trend? And what caused the defor- R. Blaustein and David B. Wake; Scientific American, April mities? As researchers elsewhere in the country began investi- 1995]. Both trends are disturbing in their own right and are also gating their local amphibian populations, it became clear that a warning for the planet [see box on page 63]. Amphibians this bizarre collection of ailments was not confined to Min- have long been regarded as important indicators of the earth’s nesota. Since 1995, malformations have been reported in more health because their unshelled eggs and permeable skin make than 60 species, including salamanders and toads, in 46 states. them extremely sensitive to perturbations in the environment. In some local populations 80 percent of the animals are af- Chances are good that factors affecting these animals harshly flicted. International reports show that this phenomenon ex- today are also beginning to take a toll on other species. tends beyond the U.S. Surprising numbers of deformed amphibians have been found in Asia, Europe and Australia as An Early Suspect well. Worldwide, extra legs and missing legs are most common. ONE PUTATIVE CAUSE of the deformities, excess exposure The aberrations cannot be discounted as being a normal to ultraviolet radiation, came under suspicion almost as soon part of amphibian life. Research dating back to the early 1900s as the malformations were discovered, because it had already indicates that a few individuals in every population have de- been implicated in declines of amphibian populations and be- fects resulting naturally from genetic mutation, injury or de- cause laboratory work had shown it to be capable of disrupt- velopmental problems. In healthy populations, however, usu- ing amphibian development. This form of radiation—which ally no more than 5 percent of animals have missing limbs or can damage immune systems and cause genetic mutations, digits; extreme deformities, such as extra hind legs, are even among other effects—has been reaching the earth in record less common. Moreover, fresh reviews of historical records by doses since chlorofluorocarbons and other human-made Minden Pictures one of us (Johnson) and new field studies indicate that deformities have become more prevalent in recent times. ALARMING LEGS: Ecologist Andrew R. Blaustein eyes malformed Pacific

Over the past eight years, dozens of investigators have tree frogs collected from farm ponds in northwestern Oregon. FRANS LANTING

BY ANDREW R. BLAUSTEIN AND PIETER T. J. JOHNSON

60 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. Chances are good that the factors affecting amphibians are also taking a toll on other species.

chemicals began thinning the protective can avoid the continuous exposure to ra- much can lead to deformities in embryos. layer of ozone in the stratosphere, a prob- diation studied in the EPA experiments. Indeed, numerous miscarriages and birth lem first measured in the 1970s. Between Juvenile and adult amphibians alike can defects in humans have resulted from 1994 and 1998 one of us (Blaustein) and move in and out of sunlight, often live pregnant women’s use of acne medicines his colleagues demonstrated that expo- in muddy water, or may be nocturnal. that contain a retinoic acid derivative. sure to ultraviolet rays can kill amphibian Some biologists suspected methoprene embryos and larvae, cause serious eye Pollution’s Part might have a similar effect on frogs. In a se- damage in adult frogs, and induce various AS SOME RESEARCHERS were exam- ries of experiments in the late 1990s, the types of bodily deformities in frogs and ining the link between ultraviolet radia- EPA in Minnesota did show that high salamanders. tion and deformities, others were pursu- amounts of retinoic acid could trigger Whether exposure to ultraviolet radi- ing the influence of water pollution, such poor formation of hind limbs in frogs, ation could disrupt leg development re- as pesticide runoff. They focused on pol- but comparable tests with methoprene mained uncertain until the late 1990s, lution because so many of the early re- caused no malformations at all. Separate when Gary Ankley and his co-workers at ports of amphibian ailments came from field measurements also indicated that the Environmental Protection Agency in areas where large amounts of insecticides the pesticide could not be the sole cause. Minnesota carried out the most focused and fertilizers are applied every year. By Methoprene breaks down quickly in the experimental research on this question to the mid-1990s numerous laboratory environment, and investigators found lit- date. When the investigators shielded de- studies had shown that myriad contami- tle evidence that it persists where defor- veloping frogs from ultraviolet rays, the nants can kill amphibians, but it was un- mities are abundant. The same is true for animals grew normal limbs, whereas tad- clear whether they could induce extra or 61 other agricultural chemicals and their poles exposed to full doses of natural lev- incomplete limb formation. breakdown products that have been els of ultraviolet radiation developed with A major challenge for toxicologists is measured in locations that harbor mal- parts of their legs missing or without dig- isolating a single chemical or even a group formed animals throughout the western its. These deformities resembled some of of chemicals as a likely candidate. Mil- U.S. Pesticides are not off the hook, how- those found in wild frogs from several lions of tons of hundreds of different pol- ever. Hundreds remain untested, and sites around the country. lutants are applied annually in regions some evidence implies that certain pesti- The EPA team was quick to point out, where deformed amphibians have been cides can cause bodily damage (albeit not however, that ultraviolet radiation does found. Yet one chemical rose immediate- the formation of extra limbs). not explain all types of leg deformities ly to the top of the list: methoprene. First At the moment, then, laboratory re- seen in nature. Most notably, it does not approved for commercial use in 1975, search tentatively suggests that water lead to the growth of extra legs, one of the methoprene was promoted as a safer re- pollutants and ultraviolet radiation are deformities reported most frequently placement for the banned pesticide DDT. capable of causing disfigurement. But a since 1995. Many laboratory and field ex- Initial concern over methoprene came more potent threat appears to have a periments, several performed by Blaustein from its chemical similarity to compounds much broader impact in nature. and his colleagues, have come to the same called retinoids. These substances, espe- conclusion. Other biologists have also cially retinoic acid, play an integral role in Prolific Parasites pointed out that many wild amphibians vertebrate development; too little or too THE EARLIEST HINTS of this threat— apparently the cause of the widespread hind-leg anomalies—turned up long be- Overview/Amphibian Ailments fore the disturbing findings in Minneso- ■ Since the mid-1990s striking deformities have turned up in more than 60 ta garnered nationwide attention. In the species of frogs, toads and salamanders in 46 states and on four continents. mid-1980s, Stephen B. Ruth, then at Mon- The number of disfigured animals in some populations averages around 25 terey Peninsula College, was exploring percent—significantly higher than in previous decades. ponds in northern California when he ■ Contradictory reports have blamed the deformities on increasing exposure to found hundreds of Pacific tree frogs and ultraviolet radiation, contaminated water or a parasite epidemic. long-toed salamanders with missing legs, ■ New evidence indicates that the parasite epidemic accounts for one of the extra legs and other deformities. He sound- most prevalent deformities—extra hind legs—and strongly suggests that ed no alarm, however, because he assumed human activities such as habitat alteration are exacerbating the problem. he was seeing an isolated oddity. In 1986 Ruth asked Stanley K. Ses-

FROGS, TOADS AND SALAMANDERS have been including deserts, forests and grasslands, climbing up the long list of creatures in from sea level to high mountains. But as danger of disappearing from the earth diverse as their niches are, few are shielded entirely ever since the first reports of completely from a nearly equal variety of dwindling populations were made 20 years insults that humans inflict on them. Some ago. An obvious question for biologists is to important amphibian habitats have been what degree physical deformities are totally destroyed or are polluted to an contributing to overall population declines. intolerable degree. In other cases, people Most malformed amphibians eventually have introduced foreign animals that either vanish from a population because they can devoured or pushed out the native neither escape their predators nor hunt for amphibians. food efficiently. Events known to increase Some of the most widespread alterations the number of animals that mature into may lead to both population declines and disabled adults—such as the parasite deformities. Many studies have shown, for epidemic that is currently afflicting dozens instance, that excess ultraviolet radiation— of sites across North America—could cause resulting from human-induced ozone loss in CRACKED EARTH signals the temporary — a whole population to crash, particularly if demise of a frog habitat in the U.S. West. the upper atmosphere can inhibit limb the incidence of deformities continues to formation in amphibian juveniles or even kill increase. Although such crashes may be occurring at some sites, embryos inside their vulnerable, unshelled eggs. In the future, numerous amphibian populations have declined severely in the global warming is expected to dry out certain suitable aquatic absence of any deformities, leaving researchers to conclude habitats while elsewhere encouraging the emergence of that deformities are far from the sole basis for the declines. infections that produce abnormal development. When it comes Environmental hazards seem to be a more significant cause. to problems as pressing as these, tackling declines will most Amphibian species inhabit a wide variety of ecosystems, likely help alleviate the deformities as well. —A.R.B. and P.T.J.J.

sions, now at Hartwick College in New deformities in Ruth’s specimens: African trematode, now known to be Ribeiroia York State, to inspect his bizarre am- clawed frogs and axolotls are not known ondatrae. phibians. Sessions agreed and quickly re- to have limb deformities in nature. The re- Thinking that they may well have un- alized that they were all infected with a search that would eventually connect the covered a direct correlation between a parasitic trematode, known commonly dots between trematodes and extra or parasite epidemic and amphibian defor- as a flatworm or a fluke. The California missing legs in frogs was conducted after mities in the wild, Johnson and his team trematodes—whose specific identity was the stir of 1995. At that time, Johnson immediately collected deformed frogs unknown at the time—did not appear to pored over the scientific literature for from the same ponds and dissected them. kill their hosts outright, but Sessions sus- clues to the cause and came across the dis- In every case, they found cysts of the par- pected that their presence in a tadpole coveries made by Ruth and Sessions. asite densely clustered just below the skin mechanically disturbed natural develop- Johnson and his colleagues then conduct- around the base of the hind legs. To test ment wherever the parasites formed cysts ed broader surveys of California wetlands the idea that the trematodes were trig- in the body, most frequently near the between 1996 and 1998 and discovered gering the growth of the extra limbs, the hind legs. To test this hypothesis, he sim- that ponds where tree frogs had abnormal researchers then exposed Pacific tree frog ulated trematode cysts by implanting limbs also had an abundance of the tadpoles to R. ondatrae parasites in the small glass beads in developing limb buds aquatic snail Planorbella tenuis, one in a lab. As expected, the infected tree frogs of African clawed frogs and a salaman- series of hosts colonized by Sessions’s developed deformities identical to those der known as an axolotl. These two species, which serve as the “white rats” of ANDREW R. BLAUSTEIN and PIETER T. J. JOHNSON began exploring the potential causes of am- amphibian biology because they are easy phibian deformities as a team in 1998. Blaustein, who earned a Ph.D. in 1978 from the Uni- to breed in captivity, developed extra legs versity of California, Santa Barbara, is professor in the zoology department at Oregon State and other abnormalities—much as if they University. A behavioral and population ecologist by training, he has spent the past several Minden Pictures were parasitized. years investigating the dynamics of worldwide declines in amphibian populations, specifi- As intriguing as those experimental cally addressing the effects of ultraviolet radiation, pollutants, pathogens and nonnative THE AUTHORS results were, though, they could not prove species. Johnson, a doctoral candidate at the Center for Limnology at the University of Wis-

FRANS LANTING that trematodes were responsible for the consin– Madison, studies human influences on emerging diseases in aquatic environments.

FERTILIZER RUNOFF LIVESTOCK PESTICIDE RUNOFF MANURE

EGGS

Parasite larvae 1infect snail New larvae hatch, to 6start the cycle again

Adult parasites 5reproduce in bird

INFECTED SNAIL DEFORMED LEG ALGAL BLOOM CYST

Larvae enter 2tadpole Cyst forms in tadpole, 3disrupting development Cyst waits dormant 4for frog to be eaten

LIFE CYCLE of the trematode Ribeiroia ondatrae enables the the bird, which releases trematode eggs into the water with its parasite to induce deformities—including extra hind legs—in feces (5). When larvae hatch (6), they begin the cycle again. generation after generation of frogs. In its first larval form the Human activities can exacerbate this process, especially where trematode infects snails (1). After transforming into a second livestock manure or fertilizers enter a pond and trigger algal free-swimming form inside a snail, the parasite embeds itself blooms that nourish, and thus increase, snail populations. near a tadpole’s future hind leg (2). There it forms a cyst that Excess ultraviolet radiation and pesticide runoff—which might disrupts normal limb development and can cause the tadpole to cause other types of deformities when acting alone—may sprout extra legs as it grows into a frog (3). The disabled frog facilitate the cycle by weakening a tadpole’s immune system then becomes easy prey for the parasite’s final host, often a and making the animal more vulnerable to parasitic infection. heron or egret (4). The parasite matures and reproduces inside —A.R.B. and P.T.J.J. found in nature, including extra limbs of Sessions, Geffrey Stopper of Yale Uni- malformations and Ribeiroia infection. and missing limbs. Higher levels of in- versity and their colleagues showed that In contrast, a field study that we pub- fection led directly to more malforma- Ribeiroia can cause limb deformities in lished last year turned up 25 such habitats tions, whereas uninfected frogs devel- wood frogs and leopard frogs as well. in the western U.S. alone. Among those oped normally. Other evidence indicates that Ribei- sites, six species displayed deformities, This study turned out to be a key roia is almost always found where de- and the proportion of affected individu- breakthrough in solving the mystery of formed amphibians are present, whereas als in each population ranged from 5 to deformed amphibians. Subsequent ex- chemical pollutants are found much less 90 percent. Over the past two years, oth- periments, including one we conducted in frequently. What is more, the parasitic in- er investigators have identified Ribeiroia- 2001 on western toads, provided evidence fection seems to have skyrocketed in re- triggered deformities in Wisconsin, Illi- of Ribeiroia’s major role in disfiguring cent years, possibly reaching epidemic lev- nois, Pennsylvania, New York and Min- amphibians other than Pacific tree frogs. els. An exhaustive literature search we nesota, including the pond where the Two studies reported last summer by conducted early in 2001 identified only eight schoolchildren made headlines. Al- Joseph M. Kiesecker of Pennsylvania seven records prior to 1990 of amphibian though heightened surveillance could ac-

State University and by a team made up populations that exhibited both signiﬁcant count for some of this increase in report- DAVID FIERSTEIN

ing, the vast majority of deformed frogs have been found by people, often children, who were looking for frogs for reasons unrelated to monitoring abnormalities. Not Working Alone SCIENTISTS NOW UNDERSTAND how the life cycle of Ribeiroia helps to perpet- uate the development of deformities in generation after generation of amphibians that are unlucky enough to share a habitat with infected snails [see illustration on opposite page]. After the parasite leaves its snail host and enters a tadpole, it embeds itself near the tadpole’s hind leg. Infected tadpoles then sprout extra legs or fail to develop both limbs. In either case, the DEFORMITIES DIFFER in their most likely causes. Trematode parasites can trigger the growth of extra young amphibian becomes unable to move hind legs (left). They can also lead to poorly formed or missing hind legs, although excess ultraviolet radiation, chemical pollutants or injury from predators may also be to blame. Ultraviolet radiation properly and thus becomes easy prey for probably accounts more often for abnormalities of the eyes (right) and skin. the parasite’s final host, often a heron or egret. The parasite matures inside the We recently showed a direct relation abetted by additional factors. At times, bird and becomes reproductively active. between human habitat alteration and water pollutants or excess ultraviolet ra- Through the bird’s feces, trematode eggs sites where Ribeiroia parasites are espe- diation may act alone to cause specific enter the water. When the larvae hatch, cially abundant. Indeed, our survey of the problems, such as disfigured bodies and they find a snail and begin the cycle again. western U.S., reported in 2002, revealed eye or skin abnormalities. At other times, If a spreading epidemic of Ribeiroia that 44 of the 59 wetlands in which am- pollutants or radiation may set the stage accounts for much, or even most, of the phibians were infected by Ribeiroia were for infection by weakening an amphib- increase in frog deformities seen in recent reservoirs, farm ponds or other artificial ian’s immune system and thus leaving the years, what accounts for the epidemic? bodies of water. Fertilizer runoff and cat- animal more vulnerable to a parasitic in- Current environmental trends suggest tle manure near these habitats often en- vasion. In yet another scenario, an in- that human alteration of habitats is at courage overwhelming blooms of algae, crease in amphibian predators, such as fault. In human as well as wildlife popu- which means more food for the snails that fish, leeches or turtles, may create more lations, infectious diseases emerge or be- host Ribeiroia parasites. Larger popula- deformities by biting off tadpole limbs. come more prevalent as features of the tions of snails infected with Ribeiroia lead Clearly, amphibians are subjected to a landscape change in ways that favor the directly to more deformed frogs. Wading cocktail of agents that stress individual an- proliferation of disease-causing organ- birds, the other necessary parasite hosts, imals and then, perhaps, entire popula- isms. Reforestation of the northeastern are usually found in abundance at such tions. The challenge to scientists becomes U.S., for example, has led to the emer- human-made locales. teasing apart these agents to understand gence of Lyme disease by encouraging the Although parasitism by trematodes is their interactions. Humans and other an- proliferation of white-tailed deer, which the likeliest explanation for most out- imals may be affected by the same envi- transport ticks that harbor the Lyme bac- breaks of amphibian deformities, it is cer- ronmental insults harming amphibians. terium. On the other side of the Atlantic, tainly not the only cause and may often be We should heed their warning. the damming of African rivers has led to the spread of human blood flukes that de- MORE TO EXPLORE pend on snails as a host and cause human The Effect of Trematode Infection on Amphibian Limb Development and Survivorship. Pieter T. J. Johnson, Kevin B. Lunde, Euan G. Ritchie and Alan E. Launer in Science, schistosomiasis. During the past several Vol. 284, pages 802–804; April 30, 1999. Stockpix.com decades, alteration of habitats has also en- A Plague of Frogs. William Souder. Hyperion Press, 2000. couraged the expansion of such diseases Ecosystems, Evolution and UV Radiation. Edited by Charles S. Cockell and Andrew R. Blaustein. as hantavirus, Ebola, West Nile virus, Springer-Verlag, 2001.

STEVEN HOLT dengue fever and AIDS. Visit the North American Reporting Center for Amphibian Deformities at www.npwrc.usgs.gov/narcam/

Highly accurate yet affordable strike weapons, proved in Afghanistan, are the latest upgrades to America’s arsenal

HORNET’S STING: A U.S. Navy F/A-18 Hornet fighter-bomber armed with America’s most common GPS-aided precision bomb—the JDAM, or Joint Direct Attack Munition—patrols the skies over Afghanistan (above). Crews onboard the aircraft carrier USS John C. Stennis prepare JDAMs and laser- guided bombs for loading onto Hornets ( far right).

COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. A U.S. Special Forces team and 1,000 anti-Taliban Afghan fighters were advancing on the Kandahar airport ambush succeeded,” the squadron leader GPS-aided bomb does not require that the one cold November evening in 2001 as explains, “it could have forestalled our launch aircraft remain in the vicinity to il- Air Force Lt. Col. Tom Lawhead peered plans to take over southern Afghanistan.” luminate the target for guidance. Once re- from the cockpit of his F-16 fighter- The American strike fighters could hit leased, this true “fire and forget” weapon bomber. Even with night-vision goggles, an important target in the dark only a few operates in an autonomous, self-correct- the commander of the 389th Expedi- hundred meters from friendly forces being fashion, which makes it accurate even tionary Fighter Squadron found it difficult cause of new, highly accurate weapons in bad weather. Further, current GPS-aid- to determine whether the coalition force technology. Rather than “dumb,” or ed arms are designed to work with the lat- 15,000 feet below was making progress iron, bombs, the airplanes were carrying est infrared- and radar-targeting systems toward its objective—to cut the city’s the latest in low-cost “smart” bombs. The on American strike aircraft. They also main highway to the Pakistan border. To forward air controller on the scene had link directly to the nation’s world-span- complicate matters, one of Lawhead’s radioed a set of Global Positioning Sys- ning navigation and communications in- flight leaders had spotted a convoy mov- tem (GPS) coordinates to the patrolling frastructure, which connects control ing behind a nearby ridge. The anti-Tal- aircraft. The F-16 pilots entered the num- bases with orbital spies such as the KH- iban Afghans had already lost radio con- ber sequences into their fire-control com- 11 photo and Lacrosse radar satellites tact with a scouting party they had sent puters, which, in turn, downloaded them and an array of aerial battlefield sensor ahead, so no one knew if the approaching to microcomputers in the weapons. When platforms—all of which can help ascer- vehicles were the returning scouts or an each bomb was released, the onboard in- tain the GPS coordinates of a potential enemy ambush. ertial navigation system (INS) used the target. Among these intelligence systems The answer came within moments. As GPS positioning information to steer it to are the ever useful U-2 spy planes, the far- the convoy’s vehicles broached the ridge- an area inside a radius of 85 feet of the seeing E-8A J-STARS and RC-135 Rivet line, they doused their lights and launched specified map point half of the time. Joint reconnaissance aircraft, the sturdy a rocket-propelled grenade. A fierce fire- Afghanistan marked the first use of and reliable U.S. Navy EP-3 Aries and fight erupted. Taliban elements were GPS-aided weapons to support ground Army RC-12 patrol planes, the familiar counterattacking. services. Although the U.S. deployed lim- E-3 AWACS planes, and the newly capa- “The Special Forces’s forward air ited numbers of these arms during the ble Predator and Global Hawk surveil- controller was busy trying to figure out Kosovo intervention of 1999 and in sub- lance (and increasingly attack) drones [see where the good guys stopped and the bad sequent strikes against Iraqi air defense illustration on opposite page]. guys started,” Lawhead recalls. Only 200 sites in the northern and southern no-fly With such weapons, fewer sorties to 300 yards separated the opponents. zones, the vast majority of bombs dropped need to be flown to meet mission goals, “We waited, watching the shooting from in the Afghan conflict were satellite-guid- easing wear and tear on equipment and three miles up. Finally, [the forward air ed. Pentagon planners expect to use many personnel. Aircraft can in addition attack controller] was able to give us the coor- more of these smart weapons in the in- targets from beyond the reach of air de- dinates of where he wanted the first tense assaults that would mark any attack fense systems, saving lives and reducing bombs to go.” The air squadron swooped of Iraq. the chances of crew capture. Accidental in and dropped precision munitions that Unlike the previous generation of civilian deaths and damage to property stopped the enemy attack cold. “Had that laser- and television-guided munitions, a and infrastructure can be avoided as well. The major weakness of this technology is its susceptibility to sophisticated signal Overview/GPS-Aided Weapons jamming efforts. ■ The Pentagon has acquired a family of “smart” air-to-ground weapons that use inertial guidance technology updated by Global Positioning System (GPS) satellite A Decade’s Difference coordinates to target enemy troops and emplacements accurately from afar. GPS- GPS-AIDED WEAPONS provide a flexi- aided systems help to guide the most common of these precision munitions to bility in combat that was almost incon- within a radius of 40 feet of a designated aim point 50 percent of the time. ceivable just 10 years ago. “In Desert

■ The relative low cost of many of these smart armaments allows the U.S. to use Storm, we generally knew ahead of time ) them in mass quantities against opposing forces. Thus, aircraft and crews can what the aim point [target] of the mission attack hazardous targets from a safe distance; fewer strike sorties are was going to be,” Lawhead notes. Unfor- necessary to achieve mission objectives; and inadvertent—so-called collateral— tunately, that knowledge could not be damage to civilian lives and property can be greatly reduced (compared with the readily updated. Nowadays mission lead- preceding pages use of conventional “dumb,” or iron, bombs). ers can respond faster to changing condi-

tions, which permits much more ﬂexible U.S. NAVY (

THE LATEST GENERATION of low-cost U.S. “smart” bombs uses inertial guidance gyroscopes that are updated by geolocation GPS SATELLITE data from the Global Positioning System (GPS) for precise targeting. A network of orbiting GPS satellites provides radio signals that tracking units can translate into an accurate map position. A computer calculates the location of a target by triangulation: clocking the time it takes for the signals of three or more J-STARS satellites to reach the trackers. Strike aircraft such as F-16 Fighting Falcons (below) have several options for obtaining the coordinates of a target—in this case, a surface-to-air missile battery 2 A patrolling surveillance plane (bottom right). such as J-STARS or Rivet Joint can pinpoint a target from a long distance away and then alert attack aircraft.

1 A single aircraft (below) can monitor the radio emissions of an enemy installation from several locations along its flight path to triangulate the target’s position. STRIKE SQUADRON

3 Three aircraft in the shooter’s squadron can simultaneously monitor the enemy’s radar signals, permitting rapid triangulation via a shared wireless datalink. SMART BOMB

RADAR EMISSIONS

4 Special Forces teams that have infiltrated enemy territory can use laser range finders ENEMY SURFACE-TO-AIR and portable GPS MISSILE BATTERY devices to determine the coordinates, which they then radio in. GROUND FORCES DON FOLEY

Guidance and control system Umbilical cover Body strakes Tail fins

“DUMB” BOMB

152 inches

INTELLIGENT ADD-ON: The Joint Direct Attack Munition, or JDAM (above), is the most common of the Pentagon’s GPS-aided aerial weapons. JDAM comes as a $20,000 kit that technicians fit to “dumb” bombs costing several thousand dollars, converting them to “smart” bombs capable of pinpoint accuracy. The conversion kit comprises tail fins and body strakes, a GPS receiver and its antenna, an inertial guidance system, a mission computer (with specialized software), electric actuators to move the tail fins, and a power supply, as well as a cabling harness and connectors. Navy bomb crews on the aircraft carrier USS John C. Stennis load a JDAM onto an aircraft on the flight deck (top right). The Air Force’s B-52 bomber can fit multiple JDAMs on wing pylon racks (bottom right). use of available forces. “Of the 178 sor- viously been the sole province of expen- of our weapons to be precision-guided.” ties the 389th Squadron flew into Af- sive, low-inventory cruise and antiship Production is increasing accordingly. ghanistan, there was only one time we ac- missiles such as the Tomahawk and the Before the Afghanistan campaign, the tually attacked the target that we had Harpoon. To date, GPS weapons account Pentagon’s inventory contained approx- planned to hit ahead of time,” he says. for approximately nine tenths of all the imately 10,000 JDAMs, the predominant Better efficiency has other strategic tonnage dropped on Afghanistan. Only type of GPS-aided bomb. Boeing is now implications. The conventional wisdom about 6 percent of the ordnance launched building about 1,500 of the systems a before the 1990–91 Persian Gulf War during the Persian Gulf War was preci- month at its St. Charles, Mo., plant to fill

was that six iron bombs—about the entire sion-guided—and those were predomi- a combined U.S. Air Force and Navy or- ) load of a typical strike ﬁghter—were re- nantly laser-directed bombs, television- der for 230,000 JDAMs; that rate will rise quired to destroy a particular target. “In aimed missiles and inertially guided cruise to 2,800 a month by August.

Desert Storm, when I was dropping dumb missiles, all of which were then state-of- illustrations bombs, we would run a package of 20 to the-art. At that time, GPS was just becom- Beating the Weather 24 F-16s to get a single target with sever- ing available for navigation purposes, and THE PENTAGON developed GPS mu-

al impact points,” Lawhead says. (A tar- it had no weapons-guidance role. nitions to overcome the limitations of ); DON FOLEY ( get air base might have many hangars that “We are moving away from dumb previous-generation precision weapons, require individual aim points.) But with bombs as much as possible,” says Capt. mainly Vietnam-era laser-guided bombs,

precision weapons aimed at the same tar- Robert Wirt, program manager for con- which are still in use. These earlier sys- photographs get, “rather than 24 jets, now you’re talk- ventional strike weapons at the U.S. Naval tems are often equipped with seekers that ing two to four jets.” Air Systems Command (NAVAIR) at the home in on laser energy reﬂected off the The technology also takes relatively in- Patuxent River Naval Air Station in Mary- target. The laser designators can be expensive iron bombs—the most common land. “Given concerns over collateral dam- mounted on the attacking aircraft or an- item in the Pentagon’s aerial arsenal—and age, the need for close-air support, and the other plane or carried by an observer makes them “smart.” That means they tight quarters in which we operate, there team on the ground. Such weapons re-

can be used on critical targets that had pre- is good reason to want the lion’s share main highly valued because of their accu- U.S. NAVY AND AIR FORCE (

70 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. racy. Still, heavy cloud cover, smoke, dust lost because of receiver failure or jam- and other concealments can make them ming, the inertial system will continue to ineffective. Analysis of the air war over direct the weapon toward the last updat- Iraq and Kuwait showed that many strike ed coordinates. missions were scrubbed because pilots The JDAM was the first of the GPS- could not see their targets. “The one vari- aided air-to-ground arsenal to enter ser- able we can’t control is weather,” NAV- vice, in 1998 [see illustration on opposite AIR’s Capt. Wirt says. “All it takes is a page]. It is not a complete weapon but a cloud getting between the path of the des- strap-on tail-kit assembly that converts ignator and the target, and a normal laser- standard-issue iron warheads (which cost guided weapon would lose track.” up to a few thousand dollars each) into This shortcoming prompted then Air GPS smart bombs. The JDAM precision- Force Chief of Staff Lt. Gen. Merrill Mc- guidance modules and steering fins are Peak to create a Pentagon requirement on manufactured at relatively low cost, about May 1, 1991, for an autonomous weap- $20,000 per weapon (compared with $1 on that pilots could drop through clouds million for a single cruise missile of the and other obscuring conditions. That led type used during the Gulf War). The kit to a call for proposals for GPS-aided mu- includes a GPS receiver and antenna, an nitions that would serve both the U.S. Air IMU, a mission computer, mechanical ac- Force and the Navy. The winning idea tuators for moving the tail fins, a power had to be cheap, accurate and compatible supply, a cabling harness, and connectors. with existing weapons, aircraft platforms, The system employs mission-planning and infrastructure. Because the technical software and complementary software tasks were relatively straightforward, cost for the aircraft. was the key issue. Boeing won a compe- The JDAMs in U.S. service have a AREA INTERDICTION: Joint Standoff Weapons, tition among 12 contractors in 1995. The range of about eight miles when dropped or JSOWs, often contain lethal bomblets result was the Joint Direct Attack Muni- from an altitude of 20,000 feet. Arms that spread widely across a target area to tion, or JDAM, and its kin. Each type of maker MBDA is developing a glider at- destroy nearly everything—troops, vehicles, these so-called J-weapons has a specific tachment for JDAMs called Diamond unreinforced buildings and emplacements— in their collective path. range. “How each is used will be driven Back that will increase the range to about by the threat,” Capt. Wirt says. “How far 24 miles. “bomb truck” with several variants. do I have to stand back from the target to JDAM’s deadly cousin is the Wind JSOW-A, the first one, entered service in shoot and not go into harm’s way?” (The Corrected Munitions Dispenser (WCMD), 1999. It carries submunitions similar to designation “joint” means that these sys- a $10,000 tail-kit assembly introduced in WCMD’s—and a price tag of $220,000. tems can be deployed by aircraft from the 2000 by Lockheed Martin that fits the ex- JSOW-B, which costs $375,000 and will Navy and the Air Force.) isting family of standard cluster bombs become available this year, bears anti- These precision weapons achieve their [see box on next two pages]. The WCMD tank submunitions. unparalleled accuracy by using comple- is not equipped with a GPS receiver to up- Scheduled for 2005, the JSOW-C has mentary targeting systems to correct the date its IMU continuously, so it has about a “unitary” penetrator warhead for de- flight path charted by the munition’s on- half the range of a JDAM. stroying bunkers and other reinforced tar- board autopilot. A GPS receiver triangu- A more complex member of the J- gets; its estimated cost will be $400,000. lates a bomb’s position using navigation weapons series is the Joint Standoff Weap- Its use of GPS and IMU for initial guid- signals beamed from orbiting satellites. on (JSOW) [see box on next two pages]. ance is similar to that of JDAM, but the The GPS technology combines with an in- Built by Raytheon, JSOW is a glider bomb JSOW-C also features an imaging inertial measurement unit (IMU), which with a 500-pound warhead and wings frared seeker for terminal (last-second) plots a route using gimbal-mounted gy- that deploy en route to its destination. It guidance to the target. The seeker enables roscopic acceleration sensors. A GPS- features a maximum range of 15 to 40 the onboard computer to perform a func- IMU-guided bomb spends the first 25 to miles, depending on the altitude of its re- 30 seconds of its free fall acquiring the lease. JSOW is a totally new system, as op- MICHAEL PUTTRÉ is editor in chief of JED, GPS signals. These coordinates then up- posed to a conversion kit. As the “stand- The Journal of Electronic Defense, a date the IMU, which provides steering off” in the name of the series suggests, monthly magazine that focuses on elec- data to the weapon’s autopilot. This mis- each bomb can be released against targets tronic warfare, battle command and sion computer then modifies the flight at distances beyond the reach of short- control, reconnaissance, and precision-

path as required by deﬂecting electrically range air defense systems. The intent was THE AUTHOR guided weapons. Puttré has been a mil-

RAYTHEON actuated tail ﬁns. If the GPS signals are to produce an all-purpose carrier, a itary and technology writer for 15 years.

Joint Direct Attack Munition (JDAM) Boeing GBU-31(v)1 General purpose Mk 84 bomb 2,000

GBU-31(v)3B Hardened targets BLU-109 penetrator bomb 2,000

GBU-32 General purpose Mk 83 bomb 1,000

GBU-38 General purpose Mk 82 bomb 500

Wind Corrected Munitions Dispenser (WCMD) Lockheed CBU-103 Area soft targets CBU-87 dispenser (202 BLU-97 1,000 Martin combined-effects bomblets) CBU-104 Area denial CBU-89 Gator dispenser 1,000 (72 BLU-91 antitank mines and 22 BLU-92 antipersonnel mines) CBU-105 Antitank and vehicle CBU-97 dispenser (10 BLU-108 1,000 infrared-detonated submunitions) Joint Standoff Weapon (JSOW) Raytheon AGM-154A Area soft targets 145 BLU-97 combined-effects 1,065 (JSOW-A) bomblets AGM-154B (JSOW-B) Antitank and vehicle 6 BLU-108 IR-detonated submunitions 1,065 AGM-154C (JSOW-C) Hardened targets 500-pound-class unitary warhead 1,500

Joint Air-to-Surface Standoff Missile (JASSM) Lockheed AGM-158 High-value 1,000-pound-class unitary warhead 2,250 Martin hardened targets

tion called target-image or scene match- analyzed to determine its location and porate passive sensors. They could acquire ing, in which an infrared image is com- identity. targets by geolocation at ranges similar to pared with a stored shot of the target, ac- Lately, such direction-ﬁnding tech- those achieved today only by specialized quired previously by other reconnais- niques have made it possible to locate a electronic-intelligence-gathering aircraft. sance assets—aircraft, satellites or drones. threat emitter on the surface of the earth The F-22 is expected to become opera- The longest-range and most sophisti- within a radius tight enough for a GPS- tional in early 2006, with the F-35 fol-

cated of the initial batch of J-weapons is aided weapon to be sent to those coordi- lowing within a few years after that. ) the Joint Air-to-Surface Standoff Missile nates to destroy it. This geolocation ca- (JASSM), made by Lockheed Martin [see pability supports a U.S. doctrine to re- Jamming vs. Antijamming box above]. JASSM completed tests in place active radar on attacking aircraft THE SAME GPS SIGNALS that are so bottom middle late 2001 and is expected to enter service with newer, “passive” sensors, which do pivotal for precision bombing, however, this year. A jet engine powers the cruise not emit telltale signals. Passive radar are also their principal weak point. Be- missile to a range of about 200 miles. The warning receiver systems on tactical air- cause the signals are faint, they are high- 1,000-pound penetrator warhead is de- craft measure Doppler shifts in an enemy ly susceptible to jamming. They are trans- ); RAYTHEON (

signed to engage high-value, well-defend- radar resulting from the host aircraft’s mitted to ensure a minimum signal pow- bottom

ed targets. Like JSOW-C, the estimated own motion. A special ranging algorithm er level of between –160 and –166 dBW and $700,000-plus JASSM has an imaging in- compares the Doppler shift with the host (160 to 166 decibels below one watt) at frared terminal seeker in addition to its aircraft’s GPS and INS to derive precise the earth’s surface. This is comparable to GPS-IMU midcourse guidance. direction and location readings. Also, the light from a 25-watt lightbulb as seen top middle three or more aircraft can triangulate on from 10,000 miles away. Put another Passive Aggression the emitter and share information via a way, GPS signals have one billionth the GPS- AIDED PRECISION weapons can wireless datalink at the same time. power of those received by a television also take advantage of transmissions The next-generation U.S. tactical air- set’s antenna. Interfering with such weak made by the enemy. Almost every mod- craft, the F-22 Raptor air-superiority signals is easy, so weapons makers incor- ); LOCKHEED MARTIN ( ern military unit or system emits signals ﬁghter and F-35 Joint Strike Fighter, will porate one or more antijamming features top of one kind or another in the course of its have greater capabilities than current air- into the receiver design. For example,

mission, and these can be intercepted and craft because they are designed to incor- GPS receivers with multiple channels can U.S. NAVY (

153 15 40 $20,000 (kit) + 1998 All JDAM tail-kit assemblies include GPS receiver $3,000 (bomb) 149 15 40 $20,000 (kit) + 1998 $5,000 (bomb) 120 15 40 $20,000 (kit) + 1999 GBU-35 version has a BLU-110 warhead payload $2,000 (bomb) stabilized for aircraft carriers 86 15 40 $20,000 (kit) + 2004 For B-2 Spirit bombers, which will carry up to 80 bombs $1,000 (bomb) 92 7 85* $10,000 (kit) + 1999 All WCMD tail-kit assemblies download GPS from aircraft $14,000 (dispenser) 92 7 85* $10,000 (kit) + 1999 $40,000 (dispenser)

92 7 85* $10,000 (kit) + 1999 $300,000 (dispenser) 160 40+ 50* $220,000 1999 All JSOWs are unpowered glide bombs with low-altitude ranges of 15+ miles 160 40+ 50* $375,000 2003 Program has been scaled back significantly 160 40+ 10 $400,000 2004 Has an imaging infrared terminal (last-second) seeker; turbojet- powered version with 120-mile range is in development 168 200+ 10 $700,000 2003 Has an imaging infrared terminal seeker, a turbojet engine and enhanced GPS-jamming resistance technology

*Area-effects munition that strikes across a wide target

acquire signals from some satellites even perience, so better training and more prac- ed caves. This technology has also yet to if others are jammed from a given direc- tice in the field should help eliminate sim- pass the test that arises between jamming tion (generally each channel receives sig- ilar errors. Whatever the case, the propor- and antijamming contingents when both nals from one satellite). Another method tion of misdirected GPS-aided munitions adversaries are technologically advanced. is to cancel out, or null, incoming jam- is low. In the main, however, the widespread ming signals using special antennas or The mountains of eastern Afghani- availability of GPS-IMU weapons is in- software signal processing. stan were an extreme proving ground for creasing the confidence of Pentagon plan- Precision systems are also not immune GPS-aided ordnance, demonstrating the ners that smaller groups of soldiers bear- to human error. In October 2001 the Pen- capabilities—and the limitations—of the ing lighter equipment can achieve victo- tagon reported that a U.S. Navy F/A-18 technology. Many times the enemy sim- ry over more numerous enemy troops Hornet fighter-bomber missed its intend- ply waited out sustained bombardment, with the aid of devastatingly precise fire- ed target with a GPS-aided bomb. The air- no matter how accurate, in well-protect- power from the sky. craft dropped a JDAM into a residential area a mile from the Kabul airport target. At least four people died, and others were A broadcast version of this article will injured. An investigation attributed the air January 21 on National Geographic Today, cause to “targeting process error.” In an- a program on the National Geographic other incident, in December of that year, Channel. Please check your local listings. three Americans and five Allied Afghan soldiers were killed when the battery for a forward air controller’s receiver was MORE TO EXPLORE changed during a bombing run. The pow- Air Warfare in the Missile Age. Lon O. Nordeen. Smithsonian Institution Press, 2002. er interruption reset the calculated target Code One. Issue on F-16 operations over Afghanistan. Vol. 17, No. 3; July 2002. Available at coordinates to those of the controller him- www.codeonemagazine.com/archives/2002/jul–02.html self, leading a misdirected JDAM to land Additional information can be obtained from JED, The Journal of Electronic Defense (www.jedonline.com), the U.S. Navy NAVAIR Integrated Battlespace Arena (ibar.nawcwd.navy.mil), on his position. These mistakes would the U.S. Air Force Combat Command (www2.acc.af.mil) and the GPS Joint Program Office seem to result mainly from operator inex- (gps.losangeles.af.mil).

www.sciam.com SCIENTIFIC AMERICAN 73 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. Drink to Your Health Three decades of research shows that drinking small to moderate amounts? of alcohol has cardiovascular benefits. By Arthur L. Klatsky A thorny issue for physicians is whether to recommend drinking to some patients Photographs by Tina West

Addressing an Illinois temperance society in 1842, Abraham Lincoln said something about “intoxicating liquor” that probably got society in general. But worry about the dangers of abuse often a frosty reception. “It is true that ... many were greatly injured leads to emotional denials that alcohol could have any med- by it,” the future president noted. “But none seemed to think the ical benefits. Such denials ignore a growing body of evidence injury arose from the use of a bad thing but from the abuse of a indicating that moderate alcohol intake wards off certain car- very good thing.” diovascular (circulatory system) conditions, most notably heart America has always had trouble deciding whether alcohol attacks and ischemic strokes (those caused by blocked blood ves- is a bad thing or a good thing. Millions who remember Prohi- sels). A few studies even show protection against dementia, which bition, when all alcoholic beverages were illegal, now witness can be related to cardiovascular problems. a constant stream of advertisements from producers of alcoholic beverages encouraging people to drink. Despite alcohol’s The Alcohol Effect popularity today, however, many still consider abstinence a A DISCUSSION OF moderate drinking requires a working de- virtue. Certainly, heavy drinking and alcoholism deserve deep finition of “moderate.” Simple definitions of light, moderate or concern for the terrible toll they take on alcohol abusers and heavy are somewhat arbitrary, but a consensus in the medical

literature puts the upper limit for moder- 25 percent of all deaths in those nations. etary habits and their respective levels of ate drinking at two standard-size drinks Pathologists uncovered the first clues various blood compounds. The comput- a day [see illustration on opposite page]. to the value of alcohol in the early 1900s, ers spit out a surprising discovery: absti- Studies show that drinking above that noting that the large arteries of people nence from alcohol was associated with a level can be harmful to overall health, al- who died of alcoholic liver cirrhosis higher risk of heart attack. though sex, age and other factors lower seemed remarkably “clean”—that is, free Various studies had missed the con- and raise the boundary for individuals. of atherosclerosis. One explanatory hy- nection because they neglected to exam- The main medical benefit of reason- pothesis assumed that alcohol was a neb- ine alcohol use as a behavior separate able alcohol use seems to be a lowering ulous solvent, essentially dissolving the from smoking. We now know that be- of the risk for coronary heart disease buildup in the arteries; another explana- cause drinkers often also use cigarettes, (CHD), which results from the buildup of tion held that heavier drinkers died be- the negative impact of smoking was atherosclerosis (fatty plaque) in the arter- fore their atherosclerosis had a chance to masking the beneficial effect of alcohol. In ies that feed blood to the heart. (The word develop. Neither idea truly explained 1974 my Kaiser Permanente colleagues “atherosclerosis” is in fact a descriptive drinkers’ unblocked arteries, however. Friedman and Abraham B. Siegelaub and union of two Greek words: athera, for A more telling hint emerged in the late I were the first, to our knowledge, to pub- “gruel” or “porridge,” referring to the fat- 1960s, when Gary D. Friedman of the lish an examination of moderate drinking ty deposits, and sclera, for “hard,” per- Kaiser Permanente Medical Center in in the absence of smoking. We saw a clear taining to the loss of vessel flexibility.) Oakland, Calif., came up with a novel connection between alcohol consumption Atherosclerosis restricts blood flow to idea: use computers to unearth unknown and a decreased risk of heart attack. the heart and can promote the formation predictors of heart attacks. The power of Since then, dozens of investigations in of vessel-blocking clots. It can thereby computing could first identify healthy men and women of several racial groups cause angina (chest discomfort resulting people who had risk factors similar to in various countries have correlated pre- from low oxygen levels in the heart mus- heart attack victims. Such factors include vious alcohol use with current health. cles), heart attack (the death of heart tis- cigarette smoking, high blood pressure, These studies have firmly established that sue that occurs when a blood clot or nar- diabetes, elevated levels of low-density- nondrinkers develop both fatal and non- rowing of the arteries prevents blood from lipoprotein (LDL, or “bad”) cholesterol, fatal CHD more often than do light to reaching the heart) and death, often with- low levels of high-density-lipoprotein moderate drinkers. In addition, in 2000 out warning. The condition usually starts (HDL, or “good”) cholesterol, male gen- Giovanni Corrao of the University of Mi- at a young age but takes decades to blos- der, and a family history of CHD. Fried- lan-Bicocca in Italy, Kari Poikolainen of som into overt CHD. The most common man then searched for predictors of heart the Järvenpää Addiction Hospital in Fin- form of heart disease in developed coun- attacks by comparing the patients and the land and their colleagues combined the tries, CHD causes about 60 percent of newly found controls in hundreds of results of 28 previously published inves- deaths from cardiovascular ills and about ways—for example, their exercise and di- tigations on the relation between alcohol intake and CHD. In this meta-analysis, they found that the risk of developing Overview/Alcohol and Heart Health CHD went down as the amount of alco- ■ An assortment of studies from around the world indicates that drinking in small hol consumed daily went up from zero to to moderate amounts decreases the risk of dying from coronary heart disease 25 grams. At 25 grams—the amount of by almost one third. alcohol in about two standard drinks— ■ Some research points to red wine as being particularly protective against an individual’s risk of a major CHD coronary heart disease. Other healthful habits of red wine drinkers, however, event, either heart attack or death—was may be partly responsible for the apparent effect. 20 percent lower than it was for someone ■ A select group of people—those with CHD or at risk for CHD and without risks who did not drink at all. associated with alcohol itself—may wish to consult their physicians about New data about alcohol protecting moderate drinking as part of a heart-healthy diet. against death from CHD are even more impressive. At a meeting of the American

76 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. Heart Association last November, my builds up in the walls of blood vessels, and Hospital revealed that alcohol intake in- Kaiser Permanente colleagues Friedman, so less atherosclerotic plaque forms. Al- creases the level of prostacyclin, which in- Mary Anne Armstrong and Harald Kipp cohol seems to have a greater influence on terferes with clotting, relative to the level and I discussed an updated analysis of a different HDL subspecies (HDL3) than of thromboxane, which promotes clot- 128,934 patients who had checkups be- on the type increased by exercise (HDL2), ting. Walter E. Laug of the University of tween 1978 and 1985, with 16,539 of although both types are protective. (The Southern California Keck School of Med- them dying between 1978 and 1998. biochemical pathways in the liver that icine showed that alcohol raises levels of CHD was responsible for 3,001 of those could account for alcohol’s ability to raise plasminogen activator, a clot-dissolving deaths. We discovered that those who HDL levels remain incompletely known; enzyme. Finally, several studies suggest had one or two alcoholic drinks a day it is thought that alcohol probably affects that alcohol lowers levels of another pro- had a 32 percent lower risk of dying from liver enzymes involved in the production moter of blood clots, fibrinogen. CHD than abstainers did. of HDL.) Three separate analyses aimed Overall, alcohol’s anticlotting capac- The possible mechanisms by which at determining specific contributions of ity is not as well established as its HDL alcohol has such an apparently profound alcohol all suggest that the higher HDL effect, and some effects, such as platelet effect on cardiovascular health primarily levels of drinkers are responsible for clumping, may be reversed by heavy or involve cholesterol levels and blood clot- about half of the lowered CHD risk. binge drinking. Nevertheless, anticlotting ting. Blood lipids, or fats, play a central Alcohol may also disrupt the com- appears to have a role in the lower risk role in CHD. Numerous studies show plex biochemical cascade behind blood for heart attacks enjoyed by moderate that moderate drinkers have 10 to 20 clotting, which can cause heart attacks drinkers. In addition, studies have shown percent higher levels of heart-protecting when it occurs inappropriately, such as a beneficial effect on CHD risk in people HDL cholesterol. And people with high- over atherosclerotic regions in coronary who have far fewer than two drinks a er HDL levels, also known to be in- arteries. Blood platelets, cellular compo- day—say, three or four drinks a week. creased by exercise and some medica- nents of clots, may become less “sticky” Anticlotting could be a major factor in tions, have a lower risk of CHD. in the presence of alcohol and therefore the protection accorded by alcohol in That lower risk stems from HDL’s less prone to clumping, although data on these small amounts, which seem insuffi- ability to usher LDL cholesterol back to this question remain ambiguous. A 1984 cient to affect HDL levels greatly. the liver for recycling or elimination, study by Raffaele Landolfi and Manfred Although alcohol reduces heart dis- among other effects. Less cholesterol then Steiner of Brown University’s Memorial ease risk mainly by raising HDL levels “STANDARD” SERVINGS OF ALCOHOLIC BEVERAGES

ALTHOUGH THERE IS NO formal definition of a standard-size 12 ounces of beer is virtually the same as is found in a 5-ounce drink, something of a consensus does exist. Beer is often sold in glass of wine or a 1.5-ounce glass of distilled spirits, such as a 12-ounce bottle or can, which is a useful reference point as vodka, gin, bourbon or scotch. Wine and distilled spirits in these one standard drink. The amount of alcohol, about 0.6 ounce, in amounts are thus also considered standard drinks.

oger R. Ecker, a cardiovascular surgeon at Summit Medical more drinks a day for men and two or more drinks a day for women. RCenter in Oakland, Calif., and I developed these charts to These charts do not apply to the following people, who should help individuals determine whether to include alcoholic beverages, abstain from alcoholic beverages: anyone under the age of 21; and in what amounts, in their diets. The charts are designed to pregnant women; nondrinkers with a family history of alcoholism, be used by physicians in consultation with patients. Coronary with moral or religious beliefs that preclude alcohol, with a heart disease (CHD) risk factors are listed at the bottom. “Light/ personal history of alcohol abuse, with known organ damage Moderate” is deﬁned as up to one standard drink a day for women from alcohol, with any chronic liver disease, or with a genetic and up to two standard drinks a day for men. “Heavy” is three or risk of breast or ovarian cancer. —A.L.K.

MEN AGE 21 to 39 / WOMEN AGE 21 to 49 MEN AGE 40 AND OLDER / WOMEN AGE 50 AND OLDER NONDRINKERS NONDRINKERS Has diabetes or Has diabetes or 0 or 1 CHD risk factor CHD or has 2 or more No CHD risk factor CHD or has 1 or more CHD risk factors other than current age CHD risk factors other than current age No change for health reasons Should consider No change for Should consider 1 to 3 standard health reasons 1 to 3 standard drinks a week drinks a week HEAVY DRINKERS HEAVY DRINKERS Has diabetes or CHD Has diabetes or CHD 0 or 1 CHD risk factor or has 2 or more No CHD risk factor or has 1 or more CHD risk factors other than current age CHD risk factors other than current age Should abstain Should reduce to no more than 1 standard Men should reduce to no Should abstain drink a day or abstain more than 2 standard drinks a day or abstain; women should reduce to no more than 1 standard drink a day or abstain

LIGHT/MODERATE LIGHT/MODERATE DRINKERS LIGHT/MODERATEDRINKERS

Has diabetes or 0 or 1 CHD risk factor Has diabetes or 0 or 1 CHD risk factor CHD or has 2 or more other than current age CHD or has 2 or more CHD risk factors CHD risk factors other than current age No change for No change for No change for health reasons health reasons health reasons If drinking less than 1 standard drink a day, increase to 1; otherwise, no change Coronary heart disease (CHD) risk factors, according to National Cholesterol Education Program guidelines: 1. Family history of CHD (father or brother younger than 55 with CHD, 4. Total cholesterol higher than 200 mother or sister younger than 65 with CHD) 5. HDL cholesterol lower than 35 2. Smoking (if HDL is higher than 60, subtract one risk factor) 3. High blood pressure 6. Age 40 and older for men, 50 and older for women and reducing clotting, it acts in other fit appears to be related to enhanced inflammation contributes to CHD, and always that could lower the risk more sub- sulin sensitivity, which promotes proper cohol’s anti-CHD power may be related tly. Moderate drinking may lessen CHD glucose usage. (Heavy drinking, howev- to an anti-inflammatory action on the en- risk indirectly by decreasing the risk of er, has been connected to higher blood dothelial tissue that lines blood vessels. type 2 (adult-onset) diabetes, which is a glucose levels, a marker for future dia- Before accepting alcohol’s benefits, an powerful predictor of CHD. This bene- betes.) Evidence is also growing that in- epidemiologist attempts to locate hidden

78 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. The collected data make a strong case for the CARDIAC BENEFITS of controlled drinking. factors possibly at work. For instance, (In fact, however, no such confounder is drinkers, half of whom, chosen at ran- could lifelong abstainers differ from known or likely, and the 30 percent risk dom and without the knowledge of the drinkers in psychological traits, dietary reduction appears to be a probable mea- researchers, would commence a moder- habits, physical exercise habits or other sure of alcohol’s beneficial effect.) ate drinking regimen, while the other half ways that might account for their higher Because heavy drinking is not more remained abstainers. The two groups CHD risk without the need to invoke the protective than lighter drinking, this ab- would be followed for years in a search absence of alcohol? Were such traits to sence of a clear dose-response relation is for eventual differences in cardiovascular explain away alcohol’s apparent protec- also a weakness. Nevertheless, the col- disease and heart-related deaths. tion, they would need to be present in lected data make a strong case for the both sexes, various countries and several cardiac benefits of controlled drinking. I To Drink or Not to Drink racial groups. Considering that no such should note, however, that the kind of MOST PEOPLE DRINK for reasons oth- traits have been identified, the simpler and study considered to be the gold standard er than alcohol’s health benefits, and more plausible explanation is that light to in human research—a prospective ran- many of them are already using alcohol in moderate alcohol drinking does indeed domized blinded clinical trial—has not amounts that appear to promote cardio- enhance cardiovascular health. yet been done. Such a study might, for vascular health. But the accumulated re- In fact, the available evidence satisfies example, engage a large pool of non- search on alcohol’s positive effects pre- most standard epidemiological criteria for establishing a causal relation. The numerous studies examining light and mod- HOW ALCOHOL MIGHT PROTECT AGAINST CHD erate alcohol intake and health reach con- Alcohol Effect Probable Action Evidence sistent conclusions. The prospective stud- Raises blood HDL Removes and transports Solid supporting evidence; ies that exist have the correct temporal cholesterol LDL cholesterol from effect explains at least sequence—that is, individuals’ habits of vessel wall half of alcohol’s benefit interest are identified, after which their Lowers blood LDL Reduces level of one Evidence weak; effect health is monitored over the long term, cholesterol major CHD risk factor probably not independent and alcohol users have different health of diet profiles than nondrinkers do. The posi- tives associated with alcohol can be at- Lowers the oxidation Prevents the plaque Largely hypothetical, tributed to biologically plausible mecha- of LDL formation associated although antioxidants are nisms. Alcohol offers specific enhance- with LDL oxidation plentiful in red wine ment of cardiovascular health, not general Lowers levels Lessens the risk of clot Moderate supporting data protection against all illness. And alco- of fibrinogen in blood formation on hol’s effect can be identified independent atherosclerotic plaques of known “confounders,” other alcohol- Exerts other anticlotting Lessens the risk of clot Inconsistent data; related factors that could be responsible actions: lessens platelet formation on possible reversal of effect for a subject’s cardiovascular condition. stickiness; raises levels atherosclerotic plaques with heavy or binge The 30 percent reduction in risk is, of prostacylin; lowers drinking perhaps surprisingly to some, less con- levels of thromboxane vincing evidence than the arguments above, because a strong unknown con- Lessens insulin Lessens key risk factor Evidence comes from founder could still account for the con- resistance for adult-onset diabetes a small number of studies nection. To take an extreme example, and atherosclerosis consider a hypothetical set of genes that Lessens psychosocial Unclear No supporting data confers on the possessor 60 percent less stress or likely mechanism CHD risk and causes a strong predisposi- Improves conditioning Imparts better resistance Preliminary supporting tion toward liking moderate amounts of of heart muscle to damage from oxygen evidence alcohol. The independent consequences deprivation of the genes could appear causally linked. www.sciam.com SCIENTIFIC AMERICAN 79 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. WINE, BEER OR SPIRITS?

eer, wine and liquor all seem to be related to a lower risk of study. We were surprised to find that those drinking wine daily Bcoronary heart disease (CHD). A tantalizing question, had about a 25 percent lower risk of CHD death than did those however, is whether one kind of drink—wine, for example—is who drank beer and wound up taking in the same amount of better than the others. The short answer: the jury is still out. alcohol. And the wine drinkers had about a 35 percent lessened The death rate from CHD in France, CHD death risk compared with the light to where red wine consumption is common, moderate hard-liquor drinkers. Significantly, is only about half that in the U.S., despite there was no difference in apparent benefit similar fat intake and sedentary between red wine and white wine. lifestyles. That observation led to the A vexing complication of all these catchphrase “the French paradox” and studies, however, is that the overall habits the idea that red wine is the beneficial of wine drinkers, beer drinkers and hard- alcoholic beverage. This belief has a liquor drinkers tend to differ greatly. In hypothetical basis—red wine especially Denmark, for example, wine drinking goes contains a number of ingredients with hand in hand with a healthful diet (high in potential antioxidant and other fruits, vegetables, fish, salads and olive oil) atherosclerosis-fighting benefits. and two other markers for better health in An excellent 1995 Danish study, in general: higher socioeconomic status and which almost 13,000 people were higher IQ. In our California studies, those followed during a 12-year period, who preferred wine also smoked less, had suggested that wine drinkers have lower more education and had more temperate death rates from CHD than do other drinking habits than those who preferred alcohol imbibers. My Kaiser Permanente beer or hard liquor. colleagues Mary Anne Armstrong and Lifestyle differences among those who Gary D. Friedman and I published on the risk of CHD death (in prefer one type of alcoholic beverage over another thus make it 1990) and the risk of CHD hospitalization (in 1997); in these exceedingly difficult to determine whether the differences in investigations, which included almost 130,000 Californians, apparent health effects are actually related to the beverage wine and beer drinkers had a lower CHD risk than did hard-liquor type itself (and therefore to wine constituents besides alcohol), drinkers. At a meeting of the American Heart Association in to drinking pattern (imbibed slowly and with food, for wine) or to November 2002, I presented new data that updated the 1990 other factors. —A.L.K. sents a challenge to physicians. On one bers of accidents, homicides and suicides, high blood pressure (itself a risk factor for hand, mild to moderate drinking seems as well as in fetal alcohol syndrome. (No CHD, stroke, heart failure and kidney better for heart health than abstinence for conclusive evidence links light to moder- failure); and hemorrhagic stroke, in select people. On the other hand, heavy ate drinking to any of these problems.) which blood vessels rupture in or on the drinking is clearly dangerous. It can con- Heavy drinking also contributes to surface of the brain. Alcohol overindul- tribute to noncardiovascular conditions cardiovascular disorders. Too much al- gence is also related to “holiday heart syn- such as liver cirrhosis, pancreatitis, certain cohol raises the risk of alcoholic car- drome,” an electrical signal disturbance cancers and degenerative neurological dis- diomyopathy, in which the heart muscle that disrupts the heart rhythm. The name orders, and it plays a part in great num- becomes too weak to pump efﬁciently; refers to its increased frequency around particular holidays during which people ARTHUR L. KLATSKY is a senior consultant in cardiology and an adjunct investigator at the engage in binge drinking. division of research at the Kaiser Permanente Medical Center in Oakland, Calif. A graduate Given the potential dangers of alco- of Harvard Medical School, he headed the medical center’s division of cardiology from 1978 hol, how can individuals and their physi- to 1994 and directed its coronary care unit from 1968 to 1990. Since 1977 he has been prin- cians make the decision as to whether to cipal investigator of a series of studies of the link between drinking alcoholic beverages and include alcoholic beverages in their lives

THE AUTHOR health. His 1974 Annals of Internal Medicine article [see More to Explore, on opposite page] and, if so, in what amounts? The ability was the first published epidemiological report of an inverse relation between alcohol drink- to predict accurately an individual’s risk ing and coronary disease; it was cited in 1995 by the National Institute on Alcohol Abuse of a drinking problem would be a great and Alcoholism as one of 16 seminal articles in alcohol research. His most recent honor was boon; the least disputed possible conse- a Health Forum Cardiovascular Health Fellowship for 2000–2001. Klatsky has completed quence of moderate drinking is problem six marathons and in 1990 climbed Mount Kilimanjaro. drinking. Individual risk can be approxi-

80 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. women also have to consider one possi- DRINKING: RISKS AND BENEFITS ble drawback of alcohol: several studies Light/Moderate Drinking Heavy Drinking link heavy drinking—and a few even link RISKS BENEFITS RISKS BENEFITS light drinking—to an increased risk of Established Probable Noncardiovascular None breast cancer, a less common condition Heavy drinking Decreased risk of CHD Liver cirrhosis than heart disease in postmenopausal Decreased risk Pancreatitis women but certainly quite a serious one. Unresolved of ischemic stroke Certain cancers For young women, who are generally at Breast cancer Decreased risk Accidents low short-term risk of CHD and there- Fetal damage of gallstones Homicides fore may not benefit greatly from alco- Suicides hol’s positive cardiovascular effects, this Unlikely Possible Fetal damage possible breast cancer link looms larger Bowel cancer Decreased risk Degenerative in estimating the overall risks and bene- Hemorrhagic of diabetes disorders of the fits of alcohol. And for all women, the stroke Decreased risk central nervous upper limit on moderate drinking should High blood of peripheral system pressure vascular disease be considered one drink a day. (narrowing Cardiovascular The only clear-cut message regarding or clogging of the High blood pressure alcohol and health, then, is that all heavy arteries carrying Arrhythmia drinkers should reduce or abstain, as blood to the arms Hemorrhagic stroke should anyone with a special risk related and legs) Cardiomyopathy to alcohol, such as a family or personal (damaged heart history of alcoholism or preexisting liver muscle) disease. Beyond that, however, the potential risks and benefits of alcohol are mated using family and personal histories bibing the optimal amount of alcohol for best evaluated on a case-by-case basis. of alcohol-related problems or condi- cardiovascular benefit, and they should Cardiovascular surgeon Roger R. Ecker tions, such as liver disease or, of course, continue doing what they are doing. and I constructed an algorithm that can alcoholism. Even when known factors are Abstainers should never be indiscrim- help health practitioners and their pa- taken into account, however, unpre- inately advised to drink for health; most tients decide how much—if any—alcohol dictable events late in life may result in have excellent reasons for not drinking. is right for a given individual [see box on deleterious drinking changes. Yet there are exceptions. One case is the page 78]. Exactly because of these dangers, person with CHD who “goes clean”— In short, health professionals should public health concerns about alcohol un- quits smoking, switches to a spartan diet, provide balanced, objective guidelines re- til recently have been appropriately fo- starts exercising and, with good inten- garding their patients’ use of alcohol, and cused solely on the reduction of the terri- tions, gives up the habit of a nightly bot- such advice needs to be tailored to each ble social and medical consequences of tle of beer or glass of wine. This self-im- person. I believe that it is possible to define heavy drinking. And the correlation be- posed prohibition should be repealed. In a clear, safe limit for alcohol consumption tween total alcohol consumption in soci- addition, a number of infrequent drinkers that would offer a probable benefit to a ety and alcohol-related problems has might think about increasing their alco- select segment of the population. The an- been used to justify pushes for abstinence. hol intake to one standard drink daily, es- cient Greeks urged “moderation in all Ultimately, however, a more complex pecially men older than 40 and women things.” Three decades of research shows message is necessary. Merely recom- older than 50 at high risk of CHD and that this adage is particularly appropriate mending abstinence is inappropriate low risk of alcohol-related problems. But when it comes to alcohol. health advice to people such as established light drinkers at high risk of CHD MORE TO EXPLORE and at low risk of alcohol-related prob- Alcohol Consumption before Myocardial Infarction: Results from the Kaiser-Permanente lems—which describes a large proportion Epidemiologic Study of Myocardial Infarction. Arthur L. Klatsky, Gary D. Friedman and Abraham B. of the population. Of course, the most im- Seigelaub in Annals of Internal Medicine, Vol. 81, No. 3, pages 294–301; September 1974. portant steps for this group are proper Epidemiology of Coronary Heart Disease—Influence of Alcohol. Arthur L. Klatsky in Alcoholism: Clinical and Experimental Research, Vol. 18, No. 1, pages 88–96; January 1994. diet and exercise; effective treatment of Alcohol in the Western World. Bert L. Vallee in Scientific American, Vol. 278, No. 6, pages 80–85; obesity, diabetes, high blood pressure and June 1998. high cholesterol; and avoidance of tobac- Alcohol and Coronary Heart Disease. Giovanni Corrao, Luca Rubbiati, Vincenzo Bagnardi, Antonella co. But there is a place on that list of ben- Zambon and Kari Poikolainen in Addiction, Vol. 95, No. 10, pages 1505–1523; October 2000. eficial activities for light drinking. Most Alcohol in Health and Disease. Edited by Dharam P. Agarwal and Helmut K. Seitz. light to moderate drinkers are already im- Marcel Dekker, 2001. www.sciam.com SCIENTIFIC AMERICAN 81 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. WORKINGKNOWLEDGE

SYNTHETIC DIAMONDS Carbon Copy

Consumers are finding it harder to distinguish syn- HYDRAULIC PISTONS thetic diamonds from the real rocks. Since the 1950s of a diamond press squeeze a small capsule scientists have grown imitations by depositing carbon containing a seed diamond at pressures atoms onto tiny natural or synthetic seed diamonds, of 55,000 atmospheres (one million pounds per under high pressure and temperature. But ever finer square inch). An electric current heats the capsule control of the temperature gradient around the seed is to 1,400 degrees Celsius or higher. eliminating the telltale imperfections that jewelers could once detect with a magnifying glass. The synthetic approach builds up the seed slowly to prevent metal atoms needed for the process from being trapped in the growing stone, which causes no- ticeable inclusions. It takes up to a week to assemble a one-carat stone. Diamonds for industrial cutting tools Capsule can be grown faster, because inclusions do not reduce Carbon heaters hardness. Polycrystalline diamond coatings for tools HIGHER are laid down using chemical vapor deposition. TEMPERATURE The original “belt” press, which squeezes the seed Salt (electrical De Beers DTC Research Center insulator) with pistons, is still employed today by the two lead- Diamond dust ing makers of industrial synthetic diamonds: General Electric and natural-diamond king De Beers (neither Molten iron-nickel retails synthetic gems). Russian physicists have per- fected a spherical press that reportedly improves de- Carbon atoms position control, spawning clearer gems faster, but de- Seed diamond tails are proprietary. Gemesis, a start-up in Sarasota, LOWER Fla., recently hired several Russian alchemists and ); COURTESY OF CHRIS WELBOURNE TEMPERATURE plans to produce thousands of synthetic gems a year. graph The gems race has forced detection labs to invent 0.5 inch more sophisticated instruments to prevent fraud. Adamas Gemological Laboratory in Brookline, Mass., has developed a spectrophotometer that shines full- DIAMOND DUST spectrum light through a stone and detects specific in the capsule diffuses down wavelengths that are absorbed by occasional nitrogen through a molten mix of iron and atom clusters, common in natural stones but not in nickel, in one commercial process. synthetics. Other instruments sense a stone’s photo- The dust dissolves in the hot melt, luminescence in laser light. then precipitates out one carbon Diamond distributors worry that the spread of ); ADAMAS GEMOLOGICAL LABORATORY ( atom at a time onto the cooler seed quality synthetics could erode consumer confidence in below, just the way water vapor authentic gems. But if a synthetic stone is the same as precipitates as fog and clings to illustrations a natural one, atom by atom, isn’t it a real diamond? cooler grass as dew. The seed is a Readers may think twice about using that logic on tiny natural or synthetic diamond Valentine’s Day: “Honey, this diamond symbolizes fragment and grows about one carat my love. I bought it at Home Depot, right next to the a week. If pressure drops, the carbon

power tools.” —Mark Fischetti DANIELS & ( atoms form graphite.

82 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. ➤ CUBISM INDEED: Cubic zirconium “gems” were the first successful atmospheres and up to 2,500 degrees C can essentially straighten simulated diamonds, but they do not qualify as synthetics because the deformed crystal planes, creating a perfectly clear gem in a few they are not carbon. Zirconium oxide powder is melted at atmospheric minutes. “Browns” purchased for a few hundred dollars could be sold W... pressures to about 2,400 degrees C with other compounds, such as for $10,000 if clarified—perhaps a better payoff than growing syn- O calcium or magnesium oxide, and crystallizes out when cooled. Sim- thetic diamonds from seed, which is expensive.

KN ple thermal detectors can identify these look-alikes. ➤ U FIRST TO PRESS: Baltazar von Platen of ASEA Laboratory in Stock- ➤ DEFORMED PRICES: Diamonds aren’t quite pure carbon; other holm is reputed to have made the first synthetic diamond in 1953, but YO atoms occupy occasional crystal sites, giving stones their color, such he didn’t publish his results. In 1955 a General Electric team led by H. D as nitrogen (yellow) or boron (blue). About 1 percent are nitrogen- Tracy Hall became the first on record to transform carbon into dia-

DI free, but they can have a brown cast because of crystal deformation. mond. Hall and his son David R. Hall now oversee Novatek in Provo, Pressing these stones in a synthetic-diamond machine beyond 60,000 Utah, which manufactures the presses that make synthetic stones.

Pressure

Electric current

NATURAL DIAMOND (left) has an octahedral crystal structure, visible during fluorescence after being illuminated with ultraviolet light. Synthetic WALL diamond (right) contains cubic sectors, also visible during fluorescence.

100 CAPSULE Synthetic 80 diamond Natural diamond 60

Transmittance (percent) 20 PISTON 0 300 400 500 600 700 Wavelength (nanometers)

SPECTROPHOTOMETER shines full-spectrum light through a synthetic diamond and a natural diamond of the same color and grade. Nitrogen atoms in the natural stone absorb blue light in a characteristic pattern from 430 to 480 nanometers; the man-made stone does not. Pressure

This month’s topic was suggested by reader Thomas Boehm. HYDRAULIC ARM Have an idea for a future column? Send it to [email protected] www.sciam.com SCIENTIFIC AMERICAN 83 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. TECHNICALITIES

Robots That Suck HAVE THEY FINALLY COME OUT WITH A ROBOT FOR THE REST OF US? BY GEORGE MUSSER

For generations, tinkerers have been pointing out how much their projects will lighten the load of housework. For generations, spouses and parents have failed to be impressed by these claims. When I built my first robot seven years ago, people kept asking, “So what does it do?” I explained that it would eventually vacuum the floor. I should have just been honest: “Not much, but it sure is cool, isn’t it?” All these years later I still have trouble getting my creations to do the most basic things, like move in a straight line. My professions of usefulness don’t carry much weight around the house anymore. At least I am not alone. Seldom in the history of technology has an industry been so eagerly anticipated, and so slow to emerge, as the consumer robot industry. DON’T CRY OVER SPILLED DETERGENT if you have the Roomba floor cleaner, the first home robot that is both genuinely useful and reasonably priced. It won’t completely relieve you of vacuuming duties, Back in the early 1980s, when computers though. The robot is about 10 inches (25 centimeters) in diameter. were turning from hobbyist playthings into mass-market appliances, it looked as though robots would soon follow. Through the school of hard knocks in a highly controlled environment. The Heathkit’s famous Hero I robot kit came (lots of them), robot experimenters have next step up is to do a single task in a out in 1982, not long after the original learned to keep things simple. Massachu- highly uncontrolled environment, and the IBM PC. Entrepreneur magazine pre- setts Institute of Technology professor most obvious candidate for that is vacu- dicted a $2-billion home robot market by and robo-guru Rodney A. Brooks led the uming. Over the past several years, a 1990. Today the original PC is a museum way in the mid-1980s with a new style of number of companies have promised to piece, and Hero I is still the state of the art. robot programming, in which cheap sen- roll out floor-cleaning robots. A few of Anyone who builds a robot appreci- sors directly trigger elementary behaviors. them have even delivered. ates what happened. When humans use a Most robot kits these days, such as Lego Apart from DustBot, a cheap but personal computer, we enter into the com- Mindstorms, embrace this approach. And clever toy made by the Japanese compa- puter’s world. If it can’t do something, or a similar design philosophy is reviving the ny Tomy, the first consumer robot that if it crashes, too bad; we have to deal. But fortunes of the home robot industry. could vacuum was Cye. Released in 1999 a robot enters into our world. If floors are Some products, admittedly, achieve by Pittsburgh-based Probotics, Cye is the uneven, if legs get in the way, if lighting simplicity by giving up the pretense of do- Apple II of robots: just pull it out of the conditions change, the robot has to deal. ing anything useful at all. Robot dogs box and plug it in. I tested one back in the Extra computing power doesn’t neces- such as Sony’s Aibo are the classic exam- fall of 2000. It’s about the size of a toast- sarily help; on the contrary, more sophis- ple. Others, such as robotic lawnmowers er oven, with two wheels, a pair of wheel

tication typically means less resilience. and pool cleaners, aim to do a single task odometers to measure its movement, and BETH PHILLIPS

84 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. a bump switch to sense when it hits some- hubcap and weighs about six pounds. thing. To prove its usefulness, it can tow The main cleaning mechanism is basically a small upright vacuum cleaner. a Bissell carpet sweeper—one of those rug You control Cye from a PC via a wire- cleaners that is often found (and sometimes less link, and the desktop software is used) in college dorm rooms. A zigzag- where Cye really shines. As the bot blun- ging wire forms a cage to keep the rotating ders around, it relays back odometry read- brush from choking on the corners of rugs. ings, and the software estimates its posi- A miniature weed whacker on the side tion by dead reckoning. Crucially, the flicks dust away from the base of walls. Be- software keeps track of the uncertainty in hind the sweeper are two squeegee blades its position; periodically the robot can re- with a narrow slot between them—a “mi- duce the error by reorienting against an crovacuum” designed to suck up dust and object of known position, such as a wall. hair. (Jones says the battery couldn’t pow- You can map a room, automatically cal- er a full-size vacuum.) The dirt ends up in culate paths from A to B, and designate a plastic cartridge. no-Cye zones—very handy in a home or The only controls are an “on” switch office where not everyone shares your ro- and three buttons to specify whether the botic enthusiasm. room is small, medium or large. When you For all its dummy- press one, Roomba starts proofing, though, Cye Much as I tried, moving in a spiral; after still appeals mainly to a while, it goes straight gadget freaks. The price, I couldn’t entice until it hits something, which used to be $700 Roomba to fall then turns, sometimes until the company lost down a flight heading back toward the its senses and raised it to of stairs. center of the room, other $2,700, puts off the prac- times executing a scal- tical-minded. The mapping software tends lop-shaped path to try to follow a wall. to crash, and the vacuuming mode is The overall effect is a random walk. Half primitive—the bot sweeps back and forth an hour later, give or take 10 minutes de- in a rectangular area and doesn’t suffer pending on room size, it declares victory obstacles gladly. Even I got bored. Lack- and stops. You can also stop it by picking ing other sensors or the provision to run it up using the built-in handle. A battery your own programs, Cye isn’t capable of charge lasts about an hour and a half. the richness of behavior that even entry- I tried Roomba on low-pile carpets level kits can provide. and hardwood floors in rooms both emp- Last October, Brooks’s own firm, iRo- ty and full. It didn’t damage or topple any- bot, based in Somerville, Mass., brought thing, and it did remarkably well at extri- out Roomba, a robot tailor-made for vac- cating itself from power and phone cords, uuming. The lead designer, Joseph L. either by shifting direction or temporarily Jones, is co-author of the 1993 book Mo- shutting off the brush. The edge detector— bile Robots: Inspiration to Implementa- downward-pointing infrared sensors that tion, which remains the single best guide watch for drop-offs—worked perfectly. for beginning hobbyists (it got me started). Much as I tried, I couldn’t entice Room- The main subject of the book, the Rug ba to fall down a flight of stairs. I even put Warrior project, grew out of a floor-clean- it on a table and let it clear off the crumbs. ing bot that Jones had built for a contest Roomba slurped up most of the filth, at M.I.T. Four years ago he and mechan- but it didn’t replace the need for manual ical engineer Paul Sandin finally got com- vacuuming or sweeping, and iRobot is pany backing to turn it into a product. wise not to claim that it does. The real Roomba is roughly the size of a car Achilles’ heel of the robot, though, is the

wire that is supposed to keep rug corners from jamming the brush. It got yanked off within a couple runs, and the company had to send me a new one. Even with the wire, the bot didn’t like the kilim in our living room one bit. And although it was usually able to free itself from cords, “usually” wasn’t good enough: it got hung up at least once per run. You don’t have to watch Roomba continuously, but you had better be nearby to help it. I think it’s fair to say that Roomba rises above the level of mere gadget—but not by much. What makes it a breakthrough is the price, $200, which approaches the don’t-need-spousal-preapproval range. Roomba closely resembles a vacuum robot, Trilobite, that was introduced by Swedish appliance maker Electrolux in November 2001. Electrolux didn’t respond to repeated requests for a demo model and doesn’t sell Trilobite outside Sweden, but I tried it out in a shop on a visit there this past fall. Trilobite features a more powerful and rug-friendly vacuum; a sonar to detect obstacles, so it seldom actually makes contact with anything; and a position tracker, so it can return to its home base and plug itself in when it needs a charge. On the minus side, it lacks an edge detector, relying instead on magnetic strips that you lay around danger spots. Worse, its price, 14,000 kroner (about $1,500), is not likely to pass the spouse test. Watching these robots bumble around gives you a new appreciation for how dif- ﬁcult housework really is. It takes agility, a tolerance for imprecision, and advanced pattern-matching skills—just the abilities with which evolution on the savanna en- dowed us. Rather than ever making a robot do all that, humans might, I suspect, ﬁnd the tables turned on them: a future cyborg species could simply hire people to clean their homes for them.

For a review of another recently introduced robot, the ER1, see the online version of this article at www.sciam.com under “Technicalities.”

The Next Big Thing? USING METAPHOR INSTEAD OF MATHEMATICS, GEORGE JOHNSON BRINGS CLARITY TO THE STRANGE WORLD OF THE QUANTUM COMPUTER BY JOSEPH F. TRAUB

is another motive for studying quantum in both states at the same time, saying 1 A SHORTCUT computers. The functioning of such a de- and 0.... Therein lies the source of the THROUGH TIME: vice, which lies at the intersection of power.” Whereas three ordinary switch- THE PATH TO THE quantum mechanics, computer science es could store any one of eight patterns, QUANTUM COMPUTER and mathematics, has aroused great in- three quantum switches can hold all eight by George Johnson Alfred A. Knopf, tellectual curiosity. at once. Thus, a quantum computer could New York, 2003 ($25) George Johnson, who writes about process extraordinary amounts of infor- science for the New York Times, has set mation, and it could do so with such himself the task of deconstructing quan- speed that it essentially takes “a shortcut In the 1960s Gor- tum computing at a level that readers of through time.” don Moore made that newspaper—and this magazine—can In 1982 Richard Feynman conjec- the empirical observation that the densi- understand. He has succeeded admirably. tured that although simulations of the ty of components on a chip was doubling He explains the principles of quantum quantum world (needed for understand- roughly every 18 months. Over the past mechanics essential to quantum computing the subatomic aspects of physics and 40 years, Moore’s law has continued to ing but tells no more than necessary. “We chemistry) could never be done on a clas- hold. These doublings in chip density ex- are operating here,” he promises, “on a sical computer, they might be possible on plain why today’s personal computers are need-to-know basis.” a computer that worked quantum-me- as powerful as those that only govern- One of the things readers really need chanically. But interest in quantum comments and large corporations possessed to know about is superposition, a key puting didn’t really take off until 1994, just a couple decades ago. But in 10 to 20 principle of quantum mechanics, and when Peter Shor, a mathematician at Bell years each transistor will have shrunk to Johnson proceeds to enlighten: “In the Labs, showed that a quantum computer atomic size, and Moore’s law, which is tiny spaces inside atoms, the ordinary could be programmed to factor huge ) based on current silicon technology, is ex- rules of reality ... no longer hold. Defy- numbers—fast. There is a reason for the pected to end. This prospect drives the ing all common sense, a single particle can fascination with factoring large integers search for entirely new technologies, and be in two places at the same time. And so, (breaking the large number into the small- one major candidate is a quantum com- while a switch in a conventional computer numbers that can be multiplied togeth- puter—that is, a computer based on the er can be either on or off, representing 1 or er to produce it). “Many of society’s se- SCIENTIFIC AMERICAN principles of quantum mechanics. There 0, a quantum switch can paradoxically be crets, from classiﬁed military documents

IN A QUANTUM COMPUTER, each switch can be 1 and 0 at the same time, whereas a classical computer codes information as either 1 or 0. COURTESY OF ALFRED A. KNOPF (COLORIZATION DONE BY

88 SCIENTIFIC AMERICAN FEBRUARY 2003 COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC. to the credit card numbers sent over the THE EDITORS RECOMMEND Internet, are protected using codes based WINTER WORLD: THE INGENUITY OF ANIMAL SURVIVAL on the near-impossibility of factoring large by Bernd Heinrich. Ecco, New York, 2003 ($24.95) numbers.... Vulnerable codes are as dis- There cannot be many people who have gone into a beavers’ lodge. turbing to nations as vulnerable borders.” Heinrich, professor of biology at the University of Vermont, did that Despite such advances as Shor’s algo- in his quest to see how animals survive winter. It was a summer rithm and despite the importance for na- when the pond had dried up and the beavers were not in residence, tional security, serious impediments stand but with a flashlight and room enough to turn around, Heinrich was in the way of building a quantum com- able to conclude that the accommodation would be quite cozy for a puter. The superpositions from which beaver family in winter. Similarly trying to see for himself as much quantum computing gets its power are as possible, he describes the winter survival strategies of many lost when a measurement of the quantum animals. He marvels in particular at the success of the golden- state is made. And because the environ- crowned kinglet (Regulus satrapa), a bird “scarcely larger than a ruby- ment interacting with a quantum com- throated hummingbird” that remains active all through the winters of Maine and Alaska, its puter is akin to taking measurements, this life “played out on the anvil of ice and under the hammer of deprivation.” The kinglet, he presents a fundamental difficulty. says, symbolizes the “astounding and ingenious strategies that animals have evolved Another barrier is that although quan- for coping in the winter world.” tum computers with seven quantum bits (qubits) have been built, it is not clear THE END OF STRESS AS WE KNOW IT whether the technology used—or any oth- by Bruce McEwen, with Elizabeth N. Lasley. Joseph Henry Press, er technology—will scale up to handle Washington, D.C., 2002 ($27.95) enough qubits. Seth Lloyd of the Massa- The stress response—fight or flee when confronting danger—has served chusetts Institute of Technology has esti- humans well over the aeons, but under the multiple pressures of modern mated, for example, that interesting clas- living it gets overworked. Chronic stress can cause health problems: sically intractable problems from atomic cardiovascular diseases, disorders of the immune system, and afflictions physics can be solved by a quantum com- of the mind “if normal feelings of distress and demoralization tilt towards puter that has some 100 qubits (although clinical depression or anxiety.” The message from McEwen, head of the error correction will require many addi- Milliken Hatch Laboratory of Neuroendocrinology at the Rockefeller tional qubits). Researchers are exploring University, is that one does not have to fall victim to stress. “We cannot, and a variety of technologies for building a should not, eliminate the fight-or-flight response, for it is a powerful, highly sophisticated quantum computer, including ion traps, response. But we will be able to find ways of keeping the stress resource in balance, so nuclear magnetic resonance (NMR), quan- that it works for us and not against us.” Better-targeted medications will help. But “the tum dots, and cavity quantum electrody- best way to deal with stress is by maintaining our physical and emotional health.” namics (QED). Which of these technologies, or technologies not yet conceived, THE GOLDEN RATIO: THE STORY OF PHI, THE WORLD’S MOST ASTONISHING NUMBER will win out is not yet known. Of course, by Mario Livio. Broadway Books, New York, 2002 ($24.95) the unknown is part of the fun of science. Most schoolchildren learn the importance of the number π, or pi (3.14159...), early on in One of our most gifted science writers, their mathematical training. The area of a circle? π(r2). Circumference? 2πr. But for Johnson is a master at bringing the reader astrophysicist Livio, the number φ, or phi (1.61803...), holds more wonder. Known as the along, giving increasingly better approxi- Golden Ratio, Golden Number and other names related to gold or mations to the truth. The book is lucid, el- divinity, phi can be used to describe the characteristics of seashells, egant, brief—and imbued with the excite- sunflowers, paintings and pentagrams. Livio traces the history of ment of this rapidly evolving field. phi’s discovery in tandem with the development of arithmetic, algebra and higher mathematics, examining along the way whether Joseph F. Traub is Edwin Howard its value was factored into the construction of the Egyptian pyramids Armstrong Professor of Computer or the Parthenon of Greece. Practical examples placed throughout Science at Columbia University the story, requiring nothing more than a handheld calculator or some (homepage: www.cs.columbia. scratch paper, help to illustrate phi’s relevance to mathematics and edu/~traub). His most recent book is the world at large. Complexity and Information All the books reviewed are available for purchase through www.sciam.com (Cambridge University Press, 1998).

Five Trusty Flares BY DENNIS E. SHASHA Imagine you have two piles of six flares each. One pile, you will know you have the good pile; take its Answer to Last pile includes three useless flares. Call that the bad remaining two flares. Month’s Puzzle 1 Force C4 for seven 4 pile, although you don’t at first know which group Second warm-up: How can you achieve a ⁄ seconds, D4 for 10 is bad. To test a flare, you must light it (because probability of getting seven good flares if the bad seconds, E6 for seven they all look good). Once you do that, you’ll find pile again contains three duds? Solution: Pick a pile seconds and F6 for out whether it works or not. But even if it is good, at random to get six of the flares. Then choose the 13 seconds. The T you won’t be able to use it again. seventh flare from the other pile. You have a one-in- protein will then chime at 45 seconds Imagine, too, that you are heading for the Arc- two chance of choosing the good pile at first. If you and once every 70 tic. Can you find a testing method for selecting flares do, then you will be choosing the seventh flare from seconds afterward 3 that will yield a ⁄ 4 or better probability of ending the bad pile; you have a one-in-two chance (three (115, 185 and so on). up with five working flares at your destination? Put good out of six total) of selecting a good one. Those For a full explanation, another way, can you devise a selection approach two choices are independent, so the probability of visit www.sciam.com 1 1 1 4 2 × 2 that would be expected to provide 75 (or more) out collecting seven good flares is ⁄ ( ⁄ ⁄ ). In other Web Solution of 100 Arctic visitors with five perfect flares? How words, according to the laws of probability, 50 of For a peek at the would the probability change if the bad pile con- 100 people would be expected to choose the good answer to this tained four nonworking flares instead of three? pile, and half of those would then pick a good flare month’s problem, Warm-up: How could you be sure to get two from the bad pile, for a total of 25 percent. Note that visit www.sciam.com good flares and waste at most four, assuming the if one pile contained four bad flares, only two out of bad pile has three bad flares? Solution: Start testing six would be functional, and the probability of get- 1 1 1 flares from one pile. If you find a bad flare after light- ting seven good ones would fall to ⁄ 6 ( ⁄ 2 × ⁄ 3). ing four, you will know you have chosen the bad pile; therefore, pick any two from the other (good) Dennis E. Shasha’s latest puzzle book is Dr. Ecco’s pile. Conversely, if you find four good flares in a Cyberpuzzles, published by W. W. Norton (2002).

THE PROBLEM: Consider two piles of six ﬂares. One pile contains three flares that look good but don’t work (left). Find a testing method that would be expected to provide five working flares at least three quarters of the time, as, for example, above. HEIDI NOLAND

Sheer Lunacy WHICH IS NUTTIER: DENYING WE EVER WENT TO THE MOON OR TRYING TO CONVINCE THE TRUE NONBELIEVERS? BY STEVE MIRSKY

Once upon a time—July 20, 1969, to be in print) recently followed the second percent of Americans have doubts about specific—two earthlings got out of their man on the moon around and called him whether we ever really went (apparently little spaceship and wandered around on “a thief, liar and coward” until the 72- up from the 6 percent that a 1999 Gallup the moon for a while. Ten more earthlings year-old astronaut finally lost it and— poll identified). At first glance, that num- walked on the moon over the next three bang, zoom, to the moon, Alice—punched ber looks alarming, but I would estimate and a half years. The End. the 37-year-old Mr. X in the face. that 20 percent of Americans probably Unfortunately, not quite. A fair num- think that the Fox show Malcolm in the ber of Americans think that this whole Middle is a documentary about a family business of moon landings really is a fairy in crisis. (Sonoma State University astron- tale. They believe that the moon landings omer Phil Plait supplies the details of the were a big hoax staged on a set in the moon-landing polls and many other re- Mojave Desert, perpetuated apparently lated items on his excellent Web site, to convince everyone that U.S. technology www.badastronomy.com was the bestest in the whole wide world. Anyway, NASA’s publicity campaign Time to shave with Occam’s razor. began to retrorocket as conspiracy the- Which is the harder thing to do: Send men orists pointed to the effort as confirma- to the moon or make believe we did? The tion of something to hide and rational fact is, the brute-force physics behind thinkers contended that $15,000 to con- blasting people to the moon is simple. vince people that the world was round— You can do it with slide rules and with I mean, that we had gone to the moon— computers whose entire memory capaci- was simply a waste of money. (Actually, ties can now fit on RAM chips the size of the $15,000 was supposed to pay for a postage stamps and that cost about as rebuttal monograph by James E. Oberg, much as, well, a postage stamp. I know a serious astronomy writer who, with you can, because we did. Aldrin, has contributed to Scientific Amer- Nevertheless, last fall NASA consid- ican. As far as I’m concerned, paying a ered spending $15,000 on what amount- science writer is never a waste of money, ed to a public-relations campaign to con- but I’m severely prejudiced.) vince the unimpressed that Americans If NASA’s not paying Oberg, perhaps had in fact gone to the moon. That idea Of course, the only Fox show that fea- it could put the money to good use by hir- was mostly a reaction to a Fox television tures good science is The Simpsons, on ing two big guys to drag Neil Armstrong program, first aired in February 2001, which Stephen Jay Gould, Stephen Hawk- out of the house. Armstrong is an ex- that claimed to expose the hoax [see ing and, for that matter, Aldrin have all tremely private man, but he is also the “Fox’s Flapdoodle,” by Michael Sher- guest-starred, although there’s some in- first man on the moon, so maybe he has mer; Skeptic, Scientific American, June structive physics in The World’s Most Hi- an obligation to be a bit more vocal about 2001]. The show’s creator is a publicity larious Fatal Car Crashes—or whatever the experience. Or NASA could just buy hound who has lived up to the name in they call this week’s special in which large Aldrin a nice plaque commemorating his more ways than one by hounding Buzz objects traveling at high speed smash into most recent moon shot, in which his fist Aldrin. Mr. X (as I will call him, thereby one another. slipped the surly bonds of decorum and

denying him the joyous sight of his name The moon-hoax show claimed that 20 touched the face of Mr. X. ILLUSTRATION BY MATT COLLINS; PHOTOGRAPH FRANK VERONSKY

Why do some people get more cavities Qthan others do? Joel H. Berg, professor and chair of pediatric dentistry at the Obviously, oral hygiene is key to keeping caries under con- University of Washington School of Dentistry and president of trol. Brushing and flossing must be performed religiously, the American Academy of Pediatric Dentistry Foundation, of- preferably at least daily, to be effective. fers this answer: Dental caries, the culprit behind the creation of cavities, is the most prevalent infectious disease in humans, affecting 97 percent of people at some point in their lifetime. Many factors Why are snowflakes are involved in the progression of tooth decay. symmetrical? Caries is acid demineralization of the teeth caused by —V. Andersen, Santa Clara, Calif. plaques of biofilms, complex communities of microorganisms Q that can coat surfaces in the mouth and reduce local pH levels. Miriam Rossi, associate professor of structural chemistry at When tooth enamel is subjected to a Vassar College, explains: pH lower than 5.5, it begins to de- Snowflakes reflect the internal order of water molecules as mineralize, or break down; above this they arrange themselves in their solid forms—snow and ice. As so-called critical pH, remineralization water molecules begin to freeze, they form weak hydrogen can occur. The success of this repair bonds with one another. The growth of snowflakes (or any sub- process depends on the presence of stance changing from a liquid to a solid) is known as crystal- minerals in saliva, available fluoride lization. The molecules align themselves in their lowest-energy ions and salivary flow rate. When the state, which maximizes the attractive forces among them and demineralization side wins this tug minimizes the repulsive ones. In the water ice found on the of war over time without compen- earth, each molecule is linked by hydrogen bonds to four oth- satory remineralization, caries can progress to a visible cavity. er molecules, creating a lattice structure. All bacterial biofilms are not alike, however. Although Mu- As a result, the water molecules move into prearranged tans streptococci and other species have been implicated as pri- spaces. The most basic shape is a hexagonal prism, with hexa- mary culprits in causing caries, some people who are infected gons on top and bottom and six rectangular-shape sides. This with these bacteria don’t get cavities. So it is not simply the ordering process is much like tiling a floor: once the pattern is quantity of plaque biofilm present that leads to cavities. chosen and the first tiles are placed, then all the other tiles must Diet is another factor. Caries-causing organisms prefer sug- go in predetermined spaces to maintain the pattern. Water molars—specifically sucrose, or common table sugar—as the chief ecules settle themselves in low-energy locations that fit the energy source. The metabolism of these sugars into lactic acid spaces and maintain symmetry; in this way, the arms of the is what causes cavities. Controlling the number of sugar expo- snowflake are made. sures—by limiting the consumption of sweets—aids in the re- There are many types of snowflakes. The differentiation oc- mineralization side of the equation. curs because each snowflake forms in the atmosphere, which is Salivary flow and composition also affect cavity production. complex and variable. A snow crystal may begin developing in In short, the more saliva there is in the mouth, the better it is one way and then change in response to alterations in tempera- at natural debridement—that is, scrubbing—of caries-causing ture or humidity. The basic hexagonal symmetry is preserved, organisms and the acids they generate off the teeth. Tooth mor- but the ice crystal branches off in new directions. phology, or shape, makes a difference as well. Deep grooves on tooth surfaces (molars in particular) trap biofilms, making their For a complete text of these and other answers from

MATT COLLINS removal by brushing and flossing more difficult. scientists in diverse fields, visit www.sciam.com/askexpert