[A brief overview of the discovery of cell mortality and immortality and of its influence on concepts about aging and cancer]

Abstract

After having accomplished the miraculous performance that led us from conception to birth, then to sexual maturity and adulthood, natural selection failed to develop a more elementary mechanism capable of simply maintaining the results of this process forever. This failure is aging. Because few animals age in the wild, evolution could not give an advantage to animals with modifications due to aging. Natural selection benefits those animals that have the highest likelihood of effectively perpetuating their species because their vital systems have the larger reserve capacity they need to resist and survive predators, disease, injury, and extreme environmental conditions. Natural selection decreases after sexual maturity has been reached because at that stage the species would not derive additional advantages from individuals with larger physiological reserves. A species increases its likelihood of survival by investing its resources and energy into increasing its opportunities for fruitful reproduction rather than into prolonging its postreproductive life span. Most animals are mortal and undergo aging because investment of resources into keeping the body eternally youthful does not promote species survival as much as their investment into strategies that make reproduction more successful.