Aging is inevitable: this is gerontological dogma. And humans do inevitably grow old, which is probably why it seems so unlikely to us that other forms of life could escape aging. Escaping aging is not escaping death. Death is an inherent part of life, and it can strike any time. But the question is whether death necessarily becomes more likely as life proceeds. And it does not. The theoretical results in this monograph indicate that life provides alternative strategies. While some organisms will deteriorate over adult ages, for others mortality appears to fall or remain constant, at least over an extended period of life after reproductive maturity. This is empirically observed especially for species that keep on growing during adult ages. Perhaps the diversity of aging matches the diversity of life. My thesis, the central insight of this monograph, is: to deeply understand why some species age it is necessary to understand why other species do not.
