may provide skewed results, warns Mau-reen A. OLeary of the State University ofNew York at Stony Brook. OLearysown research demonstrates that leavingthe fossil data out of morphology-basedanalyses yields results similar to those ofthe molecular biologists, thus calling intoquestion the DNA results. She concedesthat the molecular signal is very strongbut wonders how the molecular resultswould differ if DNA data from mesony-chians were available.
Mesonychian fossils are far too old tocontain intact DNA, but researchersthought that finding an ancient whale an-kle bone would settle the debate. Artio-dactyls are characterized by certain fea-tures on one of their ankle bones (the as-tragalus), which increase mobility. Ifwhales are artiodactyls, primitive whales(those that had not yet adapted to life inthe sea) should exhibit these ankle fea-tures. In the October 1, 1998, issue ofNature, J.G.M. Thewissen, a paleontolo-gist at the Northeastern Ohio Universi-ties College of Medicine, and his col-leagues announced their discovery of twoancient whale astragali; intriguingly, the
bones do not support either hypothesis.The fossils are fragmentary, but
Thewissen believes that together theyprovide a complete picture of what ei-ther bone would have looked like in itsentirety. This composite exhibits a per-plexing combination of features: it lacksthe rounded head seen in all artiodactylastragali, but two of its other joint sur-faces match a specialized conditionfound in artiodactyls but not in mesony-chians. Our whale astragalus doesntlook like an artiodactyl, Thewissen ob-serves. Unfortunately, it also doesntlook like a mesonychian.
Despite the ambiguity of the new fos-sils, paleontologists hope to recover ad-ditional astragali from even olderwhales, which may be more diagnostic.For now, Thewissen emphasizes that allthe data should be considered. He sus-pects that convergence is confoundingthe morphological evidence but is im-pressed with the molecular evidencelinking whales and hippos. Previously Iwas convinced that whales came out ofthis mesonychian group, he confesses.Now Im on the fence. Kate Wong
The participation of SenatorJohn Glenn of Ohio in shuttlemission STS-95 made it themost ballyhooed space flight since theApollo moon landings. Millions of televi-sion viewers watched the liftoff of theshuttle Discovery and avidly followed theprogress of the nine-day mission. Glenneven made a guest appearance, via radiolink, on the Tonight Show. The publicwas clearly delighted to see the formerMercury astronautthe first American toorbit the earthreturn to space at the ageof 77. And the publicity was a muchneeded shot in the arm for the NationalAeronautics and Space Administration,which is now starting work on the con-troversial International Space Station.
But the stated goal of STS-95 was notpublicity; Glenns primary role was toserve as a guinea pig in a barrage ofmedical experiments, most of them de-signed to study the connections between
space flight and aging. The results ofthose tests wont be released for severalmonths, but scientists already know thatthe studies will not yield any conclusivefindings. The problem with the experi-ments is that they involved just one el-derly subject: Glenn himself. To drawreliable conclusions, researchers must beable to compare Glenns data with testson other senior citizens in space. ButNASA has no plans to send any moreseptuagenarians into orbit.
The scientists involved in the medicalexperiments admit that they would haveincluded more subjects if they had hadthe chance. They maintain, however, thatthe Glenn studies will prove useful byhelping them determine where to focustheir future research. Its a fishing expe-dition, says Lawrence R. Young, direc-tor of the National Space Biomedical Re-search Institute. We know theres fish inthe pond, but we dont know what weregoing to catch. There are intriguing par-allels between the symptoms of spaceflight and aging: both astronauts and theelderly suffer from loss of muscle andbone mass, sleep disturbances and im-pairment of balance. But researchers haveno idea whether the same bodily mecha-nisms are at work in both cases.
The shuttle experiments involvingGlenn were more like a doctors exami-
News and Analysis30 Scientific American January 1999
NeuroweedsWeeds appear to use the same kind ofneurotransmitting system that humansdo. Gloria Coruzzi and her colleagues at
New York Universityfound that the weedArabidopsis has genesthat encode forglutamate receptors.Glutamate is one of theneurotransmitters thehuman brain relies onfor several functions,including memoryformation and retrieval;faulty glutamatesystems have also beenlinked to mentalillnesses. Coruzzispeculates that the
glutamate receptor in the weed couldbe an ancestral method ofcommunication common to both plantsand animals.
Bacterial Turn-onsSome kinds of deadly bacteriaincluding those that cause tetanus,tuberculosis, syphilis and botulismremain innocuous until somethingtriggers their insidious activity. DagmarRinge of Brandeis University and his co-workers report in Nature that they havefound the genetic on-off switch fordiphtheria, a complex called DtxR.Latched tightly to bacterial DNA, DtxRacts as a repressor; when the hostharboring the bacteria experiences aniron deficiency, however, DtxR falls off,allowing the expression of the genesthat tell the bacteria to attack the hostcells. In principle, a new class ofantibiotics could be developed to whichbacteria would not become resistant,because the drugs would not kill thebacteria but simply keep them frombecoming virulent.
Proton ArmageddonAccording to physics theories, mosteverything in the universe decaysincluding protons. Sooner or later,matter as we know it will cease to exist.The protons lifetime is still not known,but a new, more stringent lower limithas been found by the Super-Kamiokande underground detector inJapan. The device, which last year foundthat neutrinos have a slight mass,looked for by-products of proton decay(principally, positrons and pi mesons)but found none. The research teamtherefore concludes that protons persistfor at least 1.6 1033 yearsfar longer,by 100 billion trillion years, than thecurrent age of the universe.
More In Brief on page 32
In Brief, continued from page 26
JOHN GLENNS EXCELLENT ADVENTURE
Sure, it was a publicity stunt, butscience was served, too
Arabidopsisseedlings in culture
Copyright 1998 Scientific American, Inc.
nation than a scientific study. The sena-tor wore a cardiovascular monitor dur-ing the flight to measure his heartrhythms and blood pressure and a sleepmonitor to gauge his brain waves andeye movements while he was slumber-ing. He also provided blood and urinesamples to determine how quickly hisbones and muscles were deteriorating inzero gravity. When researchers analyzethe data, they will look for unusual re-sults that may justify full-scale studies inspace. We wont get any answers fromthese experiments, says Andrew Mon-jan, chief of the neurobiology branch ofthe National Institute on Aging. But
we may get some interestingquestions.
Overlooked in the mediafrenzy over Glenns return tospace were the more sig-nificant scientific accomplish-ments of the mission. Theshuttle crew successfully re-leased and retrieved the Spar-tan 201 satellite, which pro-vided striking images of thesuns corona. The crew alsotested a platform of instru-ments that will be installedon the Hubble Space Tele-scope in 2000. In addition,
dozens of experiments were conductedin the shuttles Spacehab laboratory, in-cluding a study to determine whethernear-perfect crystals of human insulincan be grown in zero gravity.
After the flight, Glenn was a littlewobbly on his feet, but after a goodnights sleep he said he was back to nor-mal. When the seven crew members re-turned to Houstonhome of the NASAJohnson Space Center1,000 peoplegathered at the airport to welcome them.Houston Mayor Lee Brown said theflight had renewed an American loveaffair with space travel. The questionnow is: Will the love last?Mark Alpert
News and Analysis32 Scientific American January 1999
A Weapon against MSPositive results are in from the mostextensive clinical trial of a drug to treat aform of multiple sclerosis, in which thebodys immune system attacks thecoatings of nerve cells. The study, whichinvolved more than 500 patients in ninecountries, looked at interferon beta 1a.Derived from genetically modifiedhamster cells, the drug is identical to thehuman bodys own interferon beta,which acts to suppress wayward immuneresponses. As reported in the November7, 1998, Lancet, the drug reduced relapserates by up to one third, slowed the pro-gression to disability by 75 percent anddecreased brain lesionsall withoutsubstantial side effects.
Tag-Team VotingThe Minnesota gubernatorial electionof former pro-wrestler Jesse The BodyVentura, nemesis of Hulk Hogan, maynot have been democratically fair,
argues Donald G. Saari, amathematician at North-western University. In thethree-way race, Venturawon but did not receivemore than half of all votes.Saari says such pluralityelections are akin toranking a student whoearned three As and two Fshigher than one who gottwo As and three Bs.Elections using weighted
votes (two for the first choice, one forthe second, zero for the third), firstproposed by French mathematicianJean-Charles Borda in 1770, can moreaccurately reflect an electorates wishes.
Where the Money GoesThe National Science Foundationrecently issued a report describingtrends in venture-capital spending. Inthe U.S., such investments reached $9.4billion in 1996; the biggest recipientwas the computer-technology business,which got 32 percent of the funds.Medical/health care and telecom-munications companies were other bigwinners. In Europe, which invested anequivalent of $8.6 billion in 1996, thefocus was on industrial equipment,high-fashion clothing and consumerproducts, which received more than 30percent of the money; computer-related companies took in only 5percent. In both the U.S. and Europe,seed money for new firms accountedfor only 3 to 6 percent of the total; thebulk, more than 62 percent, went toback company expansions. Philip Yam
In Brief, continued from page 30
JOHN GLENN SUITS UPat the Kennedy Space Centerin preparation for his nine-day shuttle flight.
Meteorites have been calledthe poor mans spaceprobecheap samples ofthe beyond. In that case, cosmic raysmust be the poor mans particle acceler-ator. A cosmic-ray particle coming fromthe direction of the constellation Auri-ga, detected by an instrument in Utah in1991, had an energy of 3 1020 elec-tron voltsmore than 100 million timesbeyond the range of present accelera-tors. Such natural largesse achieves whatpurpose-built machines have longsought: a probe of physics underlyingthe current Standard Model.
For years, people thought the 1991ray and a few similar onesregistered,for example, by the Akeno Giant AirShower Array (AGASA) west ofTokyomight have been flukes. But lastsummer Masahiro Takeda of the Uni-versity of Tokyo and the rest of theAGASA team reported five more suchevents. Roughly one is seen by the arrayeach year, and there is no indication ofany limit to their energy.
Current theories say that is impossible.If these cosmic rays are protons or atom-ic nuclei, as the experiments hint, theymust be moving almost at the speed oflight. At that clip, the cosmic microwavebackground, a tenuous gas of primordialradiation that fills space, looks like athick sea. Particles wading through itlose energy until they fall below 5 1019eV, known as the Greisen-Zatsepin-Kuzmin cutoff. After traveling 150 mil-lion light-years, no ordinary particlecould still have the observed energies.
Yet astronomers have seen no plausi-
Superenergetic cosmic rays could reveal the unification
of the forces of nature
Governor of Minnesota
Copyright 1998 Scientific American, Inc.