An optimistic report on what's going on in scientific research on aging, by the publisher of Longevity magazine. As the Trekkies say, ``Live long and prosper.'' Keeton (coauthor, Woman of Tomorrow, 1985) tries to show us how to do just that, first by reviewing theories about aging and then by peering into laboratories around the world for clues on how we can achieve our potential 120-year life span. No test tube is left unturned, from Roy Walford's experiments with mice on a calorie-restricted diet--it added six months to a mouse's life and prompted Walford to limit himself to 1,650 calories a day--to the more esoteric realms of cloning organs and tinkering with the aging gene, if there is one. A chapter is devoted to free radicals, the most recent villain in scenarios about aging and illness; three chapters to diet; two to cosmetics (or ``cosmeceuticals,'' including Retin-A) and plastic surgery, and one to sex. Intriguing reports on more cutting-edge theories are brief and diluted, perhaps properly, by caveats. The bottom line to living longer seems to come down, alas, to diet, exercise, and a good attitude, at least until the scientists say ``Eureka!'' and give us mail-order replacement organs. Longevity- potential tests score responses to questions about lifestyle, diet, and attitude, and a useful appendix lists resources for information about aging. Keeton promises more than she delivers, but her enthusiasm about the possibilities of living longer, healthier lives will keep readers turning pages in search of the magic bullet against the ills of aging.