The evolution of ageing

Ageing is one of biology’s longstanding enigmas—a problem that has perplexed both medical gerontologists and evolutionary biologists alike. One of the most prominent theories on the biochemical causes of ageing is the telomere-cell senescence theory. This theory proposes that ageing is due to the build up of telomere-induced senescent cells within the body. From an evolutionary standpoint, this system is thought to have evolved via antagonistic pleiotropy. Under this view, ageing is seen as a side effect of the telomere-cell senescence system, with the primary function of it being to defend against cancer. However, there are a number of problems with interpreting the system in this way, and several lines of evidence suggest that it was selected first and foremost to cause ageing. This logically entails the view that ageing is adaptive—an idea that is currently controversial.