第十章：调整人类衰老和寿命

Humans have searched for the fountain of youth since the beginning of recorded history. Records of the primitive cultures and the religions that have shaped the societies of today tell of individuals who stepped outside the bounds of the normal life span. Abraham—the patriarch of Muslims, Jews, and Christians—lived to 200 years of age. And Abraham was a mere teenager compared with the biblical character Methuselah, who was said to have lived for 969 years. In addition, many religions involve a core belief in a place where the pain and suffering of old age are alleviated—heaven or nirvana, for example. A belief in the possibility of a long life and an end to pain reflects our most basic instinct: survival.

Scientists are not immune to the cultural forces and instinctive behaviors that drive our desire to extend life. Some biogerontologists believe that we are living in a time when the modulation of aging and longevity will soon be commonplace. These scientists suggest, for example, that with advances in stem cell research, we will be able to grow new organs from our own DNA to replace those worn out by age. The lay press and the scientific literature abound with prognostications about living to 100 years of age and why it will become the rule rather than the exception.

Are these predictions of a longer life based on a realistic interpretation of current research? Or are they simply the hopes and longings of humans striving to extend their time on Earth? In this chapter, we discuss the current state of science on the modulation of aging and longevity. We focus first on biological aging, then on the only two interventions that are scientifically established to modulate the rate of aging or longevity: (1) reducing caloric intake and (2) maintaining physical activity throughout life. Finally, we take a look at some possible implications of halting human aging and/or extending the life span.