Time of Our Lives: The Science of Human Aging

""Aging is neither inevitable nor necessary,"" declares British gerontologist Kirkwood in this unorthodox study. According to his hypothesis, which he calls the ""disposable soma theory,"" aging occurs because genes treat organisms as dispensable, investing just enough in body maintenance to enable an organism to get through its life expectancy in the wild. Kirkwood believes that freshwater hydra--tubular pond animals with remarkable regenerative powers--are immortal, a claim made by Argentinean biologist Daniel Martinez in the early 1990s. When it comes to humans, though, Kirkwood concedes that a fountain-of-youth elixir, whether obtained through gene-repair therapy or other means, is far in the future or may never exist. His survey of scientific research into the human aging process reveals clues about the origins of arthritis, memory loss, Alzheimer's disease and immune-system impairment. He dispenses sensible if unsurprising advice on how to slow one's own aging (exercise, eat fewer calories, keep up a healthy sex life, etc.) and examines anti-aging fads, including those involving melatonin, the steroid hormone DHEA and hormone replacement therapy for women. Kirkwood's more provocative ideas include an evolutionary theory to explain menopause and his argument that cancer is an accidental throwback to ""immortal"" cell-growth mechanisms that were meant to be switched off. He concludes with a weak science fiction scenario in which aging has been conquered and babies are created infrequently to replace individuals who die from accident or suicide. Agent, Felicity Bryan. (Aug.)