Literature is often composed with the intention of showing the reader how fragile human life is. Stories about the trials and tribulations of immortals are not terribly popular in this post-Romantic age, nor can writers neglect the legacy of the realists. In real human experience, everyone dies, and it is an easy matter to find meaning in a story that involves death. But what of those stories that involve the untimely absence of death, and those that make us question why some who suffer continue to live so long? The biological, psychological, social, and genetic causes of old age are not the same as common causes of death. However, individuals do die of old age, more and more frequently as modern medicine advances.
In the past 50 years, human longevity worldwide has increased by more than 40 percent. From an average life expectancy of 46 years in the early 1950s, we achieved an average life expectancy of 65 years in 1996. This adding of years to human life is perhaps the most important public health achievement of this century. Reasons for longevity are not so easy to pinpoint as reasons for death, and scientific opinion differs as to the sources of human longevity.”