January 24, 2010

USA: Will science make the 200-year-old human possible?

. NEW YORK, NY / Wall Street Journal / Life & Style / Books / January 23, 2010 BOOKSHELF Hourglass Refigured: Will science make the 200-year-old human possible? By Matt Ridley Matt Ridley is an excellent professional writer. He wrote The New York Times bestseller Genome (2006) and The Agile Gene (2004). This is Matt Ridley's Book Review of Greg Critser's new book Eternity Soup. Harmony, 234 pages, $26 There is a paradox at the heart of the debate on aging. All the recipes for averting the effects of senescence— the anti-wrinkle oils, the vitamin supplements, the testosterone shots, the strict dieting regimens—are plainly little better than snake oil. And yet something is obviously working: People are living longer and longer, and are getting healthier and healthier in old age. Experts have been predicting for decades that average life expectancy will level out, but it stubbornly keeps rising. Others have predicted a growing burden of ill health among the elderly. Yet old people are healthier than ever, much of their illness compressed into shorter periods at the end of life. Average life expectancy across the world has roughly doubled in the past century. In the U.S., the passing of every day marks another five hours added to people's lives; the number of Americans who are 100 or older has doubled since 2000. The chief cause of this remarkably benign trend is the defeat of serious infectious disease, but there are other elements as well: Heart disease is killing fewer, and stroke is striking later. Read an excerpt from "Eternity Soup" The science of age is equally paradoxical. It abounds in empirical facts about what causes aging, yet the science still lacks any convincing, unifying theory. Eating dramatically less food -- caloric restriction — makes mice live longer; just two genetic mutations can double the lifespan of a worm; breeding from the oldest flies in a test tube can double the lifespan of flies in a few generations; bats and birds, tortoises and rougheye rockfish live for decades while opossums are senile two years after birth. Naked mole rats live five times as long as their size implies they should. Single-celled creatures and animal cells in petri dishes generally can only divide 50 times before the cell line expires. But that's no help when talking about whole animals, because animal tissues apparently evade such limits. To write a book about human aging, therefore, is not easy, a bit like writing a book about gravity before Newton. In "Eternity Soup" Greg Critser has solved the problem rather neatly by meandering through the subject, meeting first the snake-oil salesmen, then the hard-headed scientists and along the way people who cannot quite be pigeonholed as either. His journey takes him from magnificent charlatans who lucratively exploit the gullible ("store your own white blood cells ready for tomorrow's medical miracles") to fascinating thinkers. They all seem to have splendidly exotic names— Rochelle Buffenstein, Leonard Hayfflick, Caleb Finch, Leonard Guarante, Aubrey de Grey—and even the sane ones have colorful careers. Steven Austad, who studies how different species of mammal age, was once a Hollywood lion-tamer. Greg Critser. Photo © AG Mongelli Mr. Critser, a witty and incisive writer, starts off by visiting an international conference of the Calorie Restriction Society in Tucson, AZ. Since permanently hungry mice live longer than those that eat normal amounts of food, apparently quite a few people have taken up the "eat less, live longer" rallying cry of the "CR" crowd. Mr. Critser introduces us to Michael Rae, who is just 21 but already obsessed with squeezing as many years out of his life as possible. Mr. Rae, the author reports, "charmed everyone by openly flossing" during a presentation, "the better to reduce his inflammatory burden." On the whole, though, these CR conventions can be testy and tense affairs: Unfortunately, semi-starvation has side effects such as apathy, grumpiness, and a loss of sexual appetite. As somebody said of giving up alcohol: You don't live longer; it just feels like it. Caloric restricters will be grumpier still when they learn in "Eternity Soup" that they have probably starved in vain. One of the fashionable theories is that each animal species has a Longevity Quotient (or LQ), which measures how long it lives relative to how long it should live, given its body size. Mice have an LQ of 0.7, human beings [3-5]. Some bats — tiny but very long-lived — have LQ's of 9 or more. Semi-starving probably lengthens life only in those species with LQ's of less than 1, such as mice — caloric restriction enables such creatures to reach their full potential life span. But it appears that semi-starving is unlikely to work for species that already live longer than they "should," such as people or bats. Illustration: Polly Becker In most of biology, it is now safe to assume that people are just big mice: We have nearly all our genes in common, after all. But in the study of aging the assumption can be dangerous. As Mr. Critser constantly reminds us, remedies for senescence that might work "in mice" or "in yeast" usually prove not to work "in human beings" or other long-lived creatures. The only primate that researchers in aging find practical to study is the Marmoset, which is about as short-lived as a grant from the National Institutes of Health. We are on our own with our elixirs. How much longer can we live? Is immortality possible? The oldest person in the world (at last report) is a Japanese woman named Kama Chinen, who is 114. She has a long way to go to catch up with Jeanne Calment, the French woman who died in 1997 at 122, the longest verified human lifespan. Those who expect people to be living to 150 or even 200 by the end of this century may be proved right -- experience has shown that it is unwise to bet against longevity optimists. But it is more likely that, with the inexorable conquest of most cancer and neurological disease on the horizon, many more of us will live to 115, in much better health than past centenarians, while the oldest-ever record will only slowly creep up. This is known as the "Rectangularization" of the survivorship curve: Almost everybody lives to his or her full potential age, then dies. Mr. Critser believes that the way to achieve rectangularization is through using conventional medical help, practicing moderation in diet, keeping busy, and hanging around young people. Sounds considerably more pleasant than ingesting hormone supplements by the handful and modeling your life on a rodent's. [rc] — Mr. Ridley's book "The Rational Optimist" will be published in May. Copyright ©2010 Dow Jones & Company, Inc.