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PLANKTON VS. GLOBAL WARMING • SAVING DYING LANGUAGES Asynchronous Microchips: Fast Computing without a Clock AUGUST 2002 $4.95 WWW.SCIAM.COM IS 95% OF THE UNIVERSE REALLY MISSING? AN ALTERNATIVE TO Taking the Terror Out of Terrorism The Search for an Anti-Aging Pill COPYRIGHT 2002 SCIENTIFIC AMERICAN, INC. contents august 2002 features SCIENTIFIC AMERICAN Volume 287 Number 2 BIOTECHNOLOGY 36 The Serious Search for an Anti-Aging Pill BY MARK A. LANE, DONALD K. INGRAM AND GEORGE S. ROTH Research on caloric restriction points the way toward a drug for prolonging life and youthful vigor. COSMOLOGY 42 Does Dark Matter Really Exist? BY MORDEHAI MILGROM Cosmologists have looked in vain for sources of mass that might make up 95 percent of the universe. Maybe it’s time to stop looking. ENVIRONMENT 54 The Ocean’s Invisible Forest BY PAUL G. FALKOWSKI Marine phytoplankton play a critical role in regulating the earth’s climate. Could they also help stop global warming? INFORMATION TECHNOLOGY 62 Computers without Clocks BY IVAN E. SUTHERLAND AND JO EBERGEN Asynchronous chips improve computer performance by letting each circuit run as fast as it can. PSYCHOLOGY 70 Combating the Terror of Terrorism BY EZRA S. SUSSER, DANIEL B. HERMAN AND BARBARA AARON Protecting the public’s mental health must become part of a national antiterrorism defense strategy. LINGUISTICS 78 Saving Dying Languages BY W. WAYT GIBBS Thousands of the world’s languages face extinction. Linguists are racing to preserve at least some of them. 42 The puzzle of dark matter www.sciam.com SCIENTIFIC AMERICAN COPYRIGHT 2002 SCIENTIFIC AMERICAN, INC. 3 SCIENTIFIC AMERICAN Volu