Who Were the First Americans? • Veggie Vaccines • Femtosecond Flashes Shadows of Other Earths SEPTEMBER 2000 $4.95 www.sciam.com Muscles &Genes ARE STAR ATHLETES BORN, NOT MADE? Brian Lewis, 1999 World Outdoor Gold Medalist Copyright 2000 Scientific American, Inc. Volume 283 www.sciam.com Number 3 COVER STORY 48 Muscle, Genes and Athletic Performance Jesper L. Andersen, Peter Schjerling and Bengt Saltin Contents September 2000 The dazzling feats of Olympic athletes depend on top-notch performance by their powerfully conditioned muscles. But conditioning can only go so far— recent research suggests that when it comes to the essential ratio of fast- to slow-twitch muscle fibers, some champions really are born, not made. Still, future genetic technologies could change even that. 58 Searching for Shadows of Other Earths Edible Vaccines 66 William H. R. Langridge One day children may get immunized by munching on modified bananas or potatoes instead of by enduring painful shots. More important, food vaccines may prevent disease in millions who now die for lack of access to traditional inoculants. Laurance R. Doyle, Hans-Jörg Deeg and Timothy M. Brown Ultrashort-Pulse Lasers: Big Payoffs in a Flash 72 John-Mark Hopkins and Wilson Sibbett A new, more direct technique for finding planets near distant stars can spot not only Jupiter-like giants but also worlds with roughly the size and composition of our own. Imaging, microelectronic manufacturing, fiber optics and industrial chemistry are eagerly adopting lasers that emit light in powerful bursts lasting only quadrillionths of a second. 80 TRENDS IN ARCHAEOLOGY Who Were the First Americans? Sasha Nemecek, staff writer If your answer was fur-clad mammoth hunters who walked across the Bering Strait, guess again. The consensus emerging now is that humans reached the Americas much earlier than had been thought, possibly by boat, and that their livelihoods depended far more on fishing, small game and collecting food. Copyright 2000 Scientific American, Inc. 3 Contents September 2000 Volume 283 Number 3 The Plan to Save Fallingwater Robert Silman Fallingwater, the stunning house regarded as Frank Lloyd Wright’s masterpiece, was in danger of collapsing, a victim of its own design flaws. Now engineers have devised a way to save it. 88 FROM THE EDITORS LETTERS TO THE EDITORS PROFILE BOOKS 8 Was philosopher Thomas Kuhn’s view of science radical or just realistic? Also, The Editors Recommend. 36 Alan Rabinowitz, finder of new species. 42 Airbus and Boeing prepare to build super-jumbo jets, but does the idea of bigger planes fly at commercial airports? CYBER VIEW 46 MP4 brings the Napster treatment to digital video. WORKING KNOWLEDGE 96 How do black boxes survive plane crashes? 98 by Shawn Carlson Kites carry eyes in the sky. MATHEMATICAL RECREATIONS by Ian Stewart The mind-bending challenge of Hex. About the Cover Photograph by Howard Schatz, Schatz/Ornstein Studio. 107 WONDERS by the Morrisons The oldest technologies. TECHNOLOGY & B USINESS THE AMATEUR SCIENTIST 104 6 12 50, 100 & 150 YEARS AGO 4 www.sciam.com CONNECTIONS by James Burke 108 ANTI GRAVITY by Steve Mirsky 112 END POINT 112 N E W S & A N A LY S I S 14 Mars: not beachfront property, but. . . 14 Freeware turn