Why do people have to grow old?

Growing old provides a sense of broader perspective, and it often makes people inclined to focus much of their efforts and energy towards bettering society and creating a better world for future generations. Some theories claim that aging is caused by injuries from ultraviolet light over time, wear and tear on the body, or byproducts of metabolism. Other theories view aging as a predetermined process controlled by genes. No single process can explain all the changes of aging. No one has definitive answers to these questions, but theories can be grouped into two camps: gradual damage over time and genetic programming. The first group of theories holds that the body ages because of wear and tear that accumulates in the tissues over the years.