The Molecular Face of Aging

摘要

Consider a human baby, so young she cannot distin-guish herself from the world. Her parents, beset by the fears and longings of adulthood, gaze anxiously upon their daughter's knitted brow. Her serious expression, at once reminiscent of her mother and comical on an infant's face, causes the parents to fret: When will the crease become a wrinkle? When will the physical assault of being alive begin? Their concern might seem absurdly premature, but the fleeting nature of life has long prompted people to wonder about the process of aging, and its impact on health. Contemporary science is wondering, too, and is rejuvenating these ancient inquiries. The direction such investigations should take was indicated a few years ago by evolutionary biologist George C. Williams at State University of New York (SUNY), Stony Brook. He warned that modern gerontological research focuses on death rather than on senescence or "the decreasing effectiveness of mechanisms by which adult organisms avoid death and loss of fitness." Williams dubbed this "the Tithonus error," after the Greek hero who became the lover of Eos, goddess of the dawn. She begged Zeus to give him immortality and Zeus complied, but Eos had forgotten to include eternal youthfulness in her request. As Tithonus aged, she locked him away, finally turning him into a cicada that could amuse her with its chirruping and shed its old skin every year.