Lenny Guarente has spent much of the last two decades patiently chipping away at the genetic and biochemical underpinnings of the aging process, an area of research often plagued by extreme hyperbole and extravagant claims.

The MIT biologist is particularly focused on one tantalizing clue: for about 70 years, researchers have known that rats tend to live longer when fed a diet that is adequate in nutrition but very low in calories. While biologists are still unsure whether severe calorie restriction will have the same antiaging effect on humans, Guarente believes he and his fellow researchers have found the genes and a mechanism responsible for delaying the aging process -- at least in lower organisms.