King David's advisers urged him to clasp a young virgin to his bosom. Pythagoras advocated a diet of acorns, fruit, and grains, while Sir Francis Bacon favored anointing the skin with ointments and pomades. Nowadays scientists turn to fruit flies for clues about how to prolong life. Michael Rose, an evolutionary biologist the University of California at Irvine, has recently reported some eyebrow-raising success. In his lab he has doubled the fruit-fly life span and believes the lessons he's learned will enable humans to do the same. He discussed his research with Discover associate editor Josie Glausiusz.