In the past, suggested remedies for aging ranged from bathing in the blood of youths to sleeping between virgins. Current antiaging lore encourages blitzing the body with antioxidants and melatonin, which at best have no proven effect and at worst could be dangerous. More recent and prosaic advice is to eat right, get plenty of sleep and exercise, and stay away from tobacco and too much alcohol.

The public is provided almost daily with easy-to-remember, sometimes changing guidelines for avoiding the effects of diseases closely associated with aging. A recent, well-publicized study suggests, for example, that one drink a day will keep death away, at least for a while and for some.

The true challenge for biologists and physicians is not to provide trendy diet tips, new health food products, or hints for life extension, but to determine aging's biological causes and to establish scientifically based rationales for avoiding or postponing the negative aspects of the inevitable process. That challenge is the subject of Steven N. Austad's book Why We Age: What Science is Discovering about the Body's Journey through Life.

Austad competently summarizes the theories developed by scientists on aging over the past few decades. His is really two books in one: a history of attempts to prolong youth, and a summary of what is known about the causes of aging. His search for understanding takes us from the roots of our gray hair, past the creaking joints, through the hormonal fluctuations of menopause to the still poorly understood cellular, biochemical, and genetic basis of aging.

After a somewhat sluggish beginning in which Austad spends too much time explaining the average life span, previous theories about aging and life extension, and why we can't believe reports of real-life Shangri Las, the book delves into more recent research, telling us what extended experiments with lab rats and limited experiments with humans have revealed about the aging process.

Today it is axiomatic that death of an organism follows the death of its cells. Austad devotes considerable space to efforts to understand cellular breakdown and how such knowledge might enable us to retard or halt aging. He also discusses the role of genetics in the aging process - long lives seem to run in families - but again, the real secrets of how, when, and why we age remain hidden.

Once Austad completes the survey of how little progress we've made in actually extending life, and tackles recent progress in understanding the aging process on the cellular and subcellular level, the book becomes hard to put aside.

Scientific research has shown that vitamin E and other antioxidants destroy free radicals, which damage DNA (and many other molecules in their vicinity). Cells do have well-described mechanisms for repairing this damage, but only if the damage is limited. If it becomes too great, or if the repair mechanisms themselves are prevented from functioning, free radical destruction can lead, over time, to genetic mutations and cancer.

Austad's explanation of how antioxidants work makes understandable the current consumer rush to health food stores. His less welcome explanation that there is no correlation between high doses of antioxidants and longer life, however, will probably not affect the supplement mania exhibited by such users.

The author also is critical of the mass appeal and use of hormone supplements such as DHEA and melatonin. He questions whether consuming large quantities of these agents, which have varied and incompletely understood effects, will have any effect on aging. Levels of these hormones decline dramatically as a function of age, but scientists have yet to determine if this drop contributes to the signs of aging or if, like wrinkles, they are a consequence of the process.

There are also interesting unknowns surrounding menopause. The reason women become unable to reproduce after a certain age is still subject to speculation. Austad shreds the recently suggested theory that women stop having their own children so they can better care for their grandchildren. Instead, he believes that menopause is a consequence of women living longer than is reproductively necessary. Female primates also undergo menopause, although few live long enough to experience it. In the case of humans, at least, menopause may hold one key to prolonging life beyond the limit which may be dictated by our genes.

Women who take progesterone and estrogen supplements, researchers have learned, have a lower risk of heart disease and of some types of cancer and other ailments. According to recent research, such women could live three or more years longer, on average, than their counterparts who forego hormone replacement therapy.

The downside, of course, is that women taking estrogen supplements face a greater risk of other types of cancer. How much the risk is increased is the subject of a large, current study. Even this risk appears to be avoidable. A recent report suggests that lower doses of estrogen may be as effective without increasing cancer risks. This study, completed after the publication of Austad's book, illustrates the speed of progress in treatment of age-related diseases.

Along with hormone replacement therapy, diet is among the most promising avenues of study for those interested in aging research and life extension. Lab rodents' life spans increase by 30 percent increase if their caloric intake is drastically reduced. Austad questions whether these lab mice are representative of other mice, or other species, because of their selective breeding. However, all mammals tested to date do show a link between limited caloric consumption and longer life. Primate experiments are in progress.

Austad warns that there is no guarantee that humans could lengthen their life span by following a strict, near-starvation diet. And, he adds, they might not want to. A largely overfed society can be socially stressful and unpleasant enough. A world of constant dieters could mean significant additional drawbacks. Perhaps the preliminary research indicating that exercise, in combination with a slight reduction in caloric intake, might provide benefits similar to that of calorie restriction alone, will assure that drastic calorie restriction need never be widely adopted. Research suggests that that although proper diet and exercise might not make it possible to live to an extraordinary age, they do seem significantly improve health during the middle years.

Although he admits there is much more to be learned about the aging process, Austad, both a professor of zoology at the University of Idaho and an affiliate professor at the University of Washington School of Medicine, and a well-known expert on aging, ends his book on a cautiously hopeful note :considerably more knowledge might now be within reach.

Biologists or anyone who has kept up with aging news in newspapers may find Austad's book too much old news and not enough good news; but for the general reader - Austad's intended audience - or any biologist who doesn't read about this subject regularly, Why We Age is a detailed, mostly entertaining primer of current theories and research into the topic. The book provides concise explanations of the advances, false starts, research, hype, and present excitement surrounding the quest for a way to stay young longer.

Beat Those Wrinkles - a review by Piers Emson of Why We Age from the September 6 issue New Scientist. Emson prefers the "rate of living" theory about why we age. This theory proposes that the faster one lives, the quicker one dies, giving couch potatoes the perfect excuse not to change their habits.

Pepper Institute On Aging and Public Policy - studies all aspects of aging, with the goal of initiating, coordinating, and facilitating research into aging and projects to serve the needs of an aging population.

Los Angeles Gerontology Research Group - links to myriad Web sites on aging, including sites on antiaging medicine, theories of aging, and physicians who specialize in "slowing down" the aging process. A mix of useful information and charlatanism.

Birthing the Crone - many women dread getting older, but one artist has dedicated a site to help women turn aging into a growing experience. "Crone" doesn't have to be a pejorative for old women, but can mean a woman made wise by life.

The University of Georgia Gerontology Center - may offer helpful information for potential graduate students, gerontologists, policy makers, administrators, and others interested in different aspects of the aging process or aging populations.

Sealy Center on Aging - a gateway for a wide variety of information and resources about aging.

National Institute of Aging Age Page: Health Quackery - snake-oil salesmen have been around for years, and the normal processes of aging are a rich territory for medical quackery. Contains information on modern quacks who say their products can stop or reverse aging or the conditions of old age, such as arthritis. Offers places victims of quacks can go to for help.

Aging Research Center - gives researchers in various fields access to the latest information on the aging process.