Different causes of aging
As to the process of aging, there seems to be a multitude of effects involved, so that we should not expect any single genetic mutation to solve the problem. One of those is the production of "free radicals" (a type of oxidyzing agents, damaging proteins necessary for the functioning of the cell) during energy production. Much of the damage done by free-radicals is repaired by the cell, but in the long term damage tends to accumulate. One of the suggested therapies to increase life-span (
life-extension) is to combat free radicals by
antioxydant chemicals such as selenium, Vitamin C and Vitamin E, or to minimize their production by calorie restriction diets.
Another one is an apparently inbuilt limit on the number of times a cell can divide (mitosis). This so-called Hayflick limit (of the order of 50 divisions) is well beyond the one that is reached during normal life, and should thus not be interpreted as a preprogrammed death. The hypothesis is that it functions to limit the risks for the development of cancer or tumors (characterized by unrestricted reproduction of cancerous cells). The mechanism seems to be that during each splitting of a cell, the chromosomes are copied incompletely, with a small stretch of DNA on the outer extremum being cut off during the split. The outer stretches of DNA (
telomeres) for a young cell are not functional, so that losing them does not impair function. But after a sufficient number of divisions, the process would start to cut off functional DNA, thus making it impossible for the cell to survive. The cutting off does not happen during cell divisions (meiosis) producing sex cells (sperm or egg cells). Otherwise each subsequent generation would have less DNA than the previous one. This reminds us of the fact that the loss of DNA is not an unavoidable effect of increase of entropy or a similar physical principle leading to aging.
Very recently, researchers have managed to synthetically produce the enzyme telomerase, which is capable of produce new telomeres. This open up new avenues to combat those forms of again linked to the Hayflick limit.