A SHARPER VIEW OF STARS • EVOLUTION: A LIZARD’S TALE MARCH 2001 $4.95 WWW.SCIAM.COM Sculpting the Earth from Inside Out If humans were built to last making sense of taste geography of poverty and wealth Copyright 2001 Scientific American, Inc. Volume 284 www.sciam.com Number 3 COVER STORY Sculpting the Earth from 40 Inside Out Contents March 2001 Michael Gurnis Powerful motions deep inside the planet do not merely shove fragments of the rocky shell horizontally around the globe— they also lift and lower entire continents. 32 Making Sense of Taste A Sharper View of the Stars Arsen R. Hajian and J. Thomas Armstrong David V. Smith and Robert F. Margolskee New optical interferometers are letting astronomers examine stars in 100 times finer detail than the Hubble Space Telescope can achieve. How do cells on the tongue register the sensations of sweet, salty, sour and bitter? Scientists are finding out—and discovering how the brain interprets these signals as various mouth-watering tastes. 56 Evolution: A Lizard’s Tale 64 If Humans Were Built to Last S. Jay Olshansky, Bruce A. Carnes and Robert N. Butler We would look a lot different— inside and out— if evolution had designed the human body to function smoothly not only in youth but for a century or more. 50 Jonathan B. Losos On some Caribbean islands, evolution appears to have taken the same turn—over and over again. An investigation of anole lizards illuminates this biological mystery. 5 Copyright 2001 Scientific American, Inc. 8 FROM THE EDITORS LETTERS TO THE EDITORS 12 50, 100 & 150 YEARS AGO 14 PROFILE 26 Anthropologist Napoleon Chagnon defends himself against Yanomamö charges. TECHNOLOGY & B USINESS 29 Devices that analyze aromas now fit on tiny chips and can convert smells into visual cues. CYBER VIEW 31 The trouble with copy protection on hard drives. WORKING KNOWLEDGE 76 How radar guns catch speeders. THE AMATEUR SCIENTIST 78 by Shawn Carlson Investigate how plants grow in reduced gravity. MATHEMATICAL RECREATIONS by Ian Stewart The divine mathematics of Easter. About the Cover Illustration by William Haxby and Slim Films. 80 84 BOOKS Body Bazaar explores today’s burgeoning market for human tissue. Also, The Editors Recommend. 89 WONDERS by the Morrisons The salty chemistry of the porcupine. CONNECTIONS by James Burke 90 ANTI GRAVITY by Steve Mirsky 92 END POINT 92 N E W S & A N A LY S I S 16 Frozen plan to penetrate Lake Vostok. 16 The end of Scotchgard. 18 Volcanic accomplices in extinction. 19 Embedding chips in polymers. 20 A lotion may reduce skin carcinomas. 21 Hovering atoms for computing. 22 News Briefs 23 By the Numbers Welcome to suburbia. 25 16 19 22 23 Scientific American (ISSN 0036-8733),published monthly by Scientific American,Inc.,415 Madison Avenue,New York,N.Y.10017-1111. Copyright © 2001 by Scientific American,Inc.All rights reserved.No part of this issue may be reproduced by any mechanical,photographic or electronic process,or in the form of a phonographic recording,nor may it be stored in a retrieval system,transmitted or otherwise copied for public or private use without written permission of the publisher.Periodicals postage paid at New York,N.Y., and at