ABSTRACT
The aging process begins at conception, and is ongoing throughout life. We are generally unaccustomed to viewing aging in this way; our attention is focused on the tremendous generation of new tissues early in life, rather than the degeneration of those which have already formed. Yet micro- and macroscopic physical, chemical and biological stresses are unavoidable, and leave their marks almost as soon as we become alive. During youth, our generative capacity renders the effects of most of these stresses trivial, though scars often remain as reminders that our ability to repair ourselves is by no means absolute. Eventually, repair mechanisms themselves become less effective; our tissues cannot keep pace with the rate of decay, and function gradually wanes.
