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CELEBRATING 165 YEARS “Super-earths” August 2010 $5.99 www.ScientificAmerican.com Secrets of Our Success Could They Harbor Life? Robot Pills Doctor in a Capsule Hardware Hackers The Next Security Threat Once humans almost went extinct. Here’s the untold story of our salvation Plus Origins Special © 2010 Scientific American Morality Animation Influenza Fireworks Swiss Cheese Barbed Wire Hand Washing Families and more Untitled-5 1 6/24/10 4:20:57 PM Untitled-8 1 6/24/10 4:34:22 PM contents features Scientific American August 2010 ■ Volume 303 Number 2 SPACE 38 Planets We Could Call Home 38 By Dimitar D. Sasselov and Diana Valencia A startling number of planets in our galaxy could be similar to Earth— and may even support life. SPECIAL REPORT 46 Origins How did sex get started? Who invented barbed wire? When did zero become something? These and other beginnings, explained. 54 When the Sea Saved Humanity By Curtis W. Marean A harsh change in climate might have wiped out Homo sapiens long ago if a lucky band of hunter-gatherers hadn’t taken shelter in an idyllic corner of Africa. MEDICINE 62 Robot Pills 62 By Paolo Dario and Arianna Menciassi Tiny devices may soon voyage through the digestive tract, performing surgery and diagnosing disease. ENVIRONMENT 66 T hreatening Ocean Life from the Inside Out By Marah J. Hardt and Carl Safina Carbon emissions are making the oceans more acidic, imperiling many species from plankton to squid. imaging 74 Filming the Invisible in 4-D 88 An amazing form of microscopy can make movies of vanishingly small, nanoscale objects in action. technology 82 T he Hacker in Your Hardware By John Villasenor Microchips in many common electronic devices might already be compromised, with dire consequences. 46 OBJECT LESSON On The Cover During a long-ago climate catastrophe a small group of Homo sapiens found refuge in a bountiful seashore near Africa’s tip. We are all the beneficiaries. Image by Jean-Francois Podevin. 2 S C I E N T I F I C A M E R I C A N 88 Plastic Surf By Jennifer Ackerman Photograph by Cary Wolinsky The unhealthful afterlife of toys and packaging. © 2010 Scientific American A u g u s t 2 0 10 Per-Anders Petterson (cover background); Frank Hülsbömer (robot pill) By Ahmed H. Zewail contents departments 6 8 12 14 From the Editor Letters 50, 100 & 150 Years Ago News Scan 12 Energy & Environment ■ ■ Gulf oil: we wanted it— now how do we get rid of it? Research & Discovery ■ ■ What’s next for cells powered by synthetic genomes? 28 ■ ■ Lab accidents haunt experimental science. ■ ■ Rapid eye movements track targets in dreams. Medicine & Health courtesy of anybots ■ ■ Lamarckian phenomena and heritable diseases. ■ ■ Dubious claims still pervade supplements industry. Technology ■ ■ Crash-testing batteries for electric-car safety. ■ ■ Instead of telecommuting, try a surrogate robot. 36 Critical Mass 30 Perspectives By Lawrence M. Krauss By the Editors Religious leaders should be held accountable when their irrational ideas turn harmful. The way to avoid ruinous oil spills is to fix our national energy policy. 90 Recommended 32 Sustainable Developments Arctic change. Malaria’s grip. Periodic table. By Jeffrey D. Sachs Economic, political and cultural forces have boosted Poland but failed Russia. 92 Anti Gr