Why do we age? The answer to this question is critical to our ability to prevent and treat highly age-related diseases such as cancer and heart disease that now cause the majority of deaths in the developed world. For centuries aging has been considered an unalterable and therefore untreatable condition. We can find treatments for individual diseases but not for aging. Consequently, the effectiveness of medical treatment declines with age. New thinking backed by recent discoveries increasingly suggests that aging is itself a treatable condition and that treatments that delay aging can be found to treat or delay occurrence of age-related diseases. Anti-aging medicine is therefore possible.
In addition, in order to understand (and find treatments for) age-related diseases we need to understand the biological mechanisms that cause the drastic increase in incidence with age. Different theories suggest very different disease mechanisms.