What is ageing and how does it occur? It is clear that there is an organized process of ageing in humans and animals that can be seen in action from birth to death. We go through stages in development that can clearly be demarcated: baby-child-teen-adult-middle aged-old. This process is certainly a genetic process, controlled by our own genes. So to those who think our genes are our friends, they can also be our enemies.
This ageing process is mimicked in us and other organisms at the cellular level. We all know that cells in our bodies divide and form new cells, but if this were true without anything else occurring all our organs would continue to grow and expand, and eventually we would burst. So logically there has to be a concurrent process that removes cells at roughly the same rate as cell division, and that process was discovered in the 1950s and is called programmed cell death or apoptosis. Cells are genetically programmed to die spontaneously in order to allow new cell growth to occur. In each organ there is a certain turnover rate of cells, some dying and some dividing. Now the argument is that because cells in our body die spontaneously, we, our whole body, must also do so, according to a certain genetic program. There is even the genetic condition of accelerated ageing in rare individuals called progeria in which the individual ages and dies within a few years.
On the other hand environmental effects also cause us to age, for example overwork, lack of food, poor hygiene, can all contribute to ageing and death. Medical injuries or infections can similarly lead to ageing and to premature death. But, although we have to a large extent overcome many infections with antibiotics and many causes of death through safety measures, we are nevertheless it seems doomed to die at a certain age. It seems unlikely that the genetic process of ageing could be stopped.
One reason we die is that we are involved in sexual reproduction. Asexual reproduction in micro-organisms means that their bodies simply divide, but this cannot work for complex higher organisms. We are too complex for asexual reproduction. So ageing and death is the price we pay for sex. Most people would agree that its worth it.