Ageing is a normal life process which all human beings must go through sooner or later, whether they want to or not. Ageing not only affects an individual physically but also psychologically and socially.
There is no doubt that most of the time physical changes are the most visible and pronounced, as they start very early on. One may say that the physical decline starts in our twenties when we have reached complete physical maturity and the end of the growth phase. With this in mind ageing can be defined as: “a continual, universal and irreversible process that determines morphological, functional and psychological changes that lead to a progressive loss in the capacity to adapt.”
But, why do we age? Although through time, there have been a variety of theories about the motive of the ageing process; there is not clear theory about what the close mechanism for why we age. Currently, in all scientific studies, it is shown that for ageing there is a genetic base for which different external agents ranging from tobacco and alcohol consumption to the most diverse illnesses that either cut down on or speed up the ageing process.
Over time, some professionals in the field have established theories regarding the reasons for the ageing process. The following table includes a summary of a few: