Biological mechanisms of ageing.

In a short review of the theories or proposed biological mechanisms of ageing it is necessary to be very selective in the ideas which are included or rejected. Although many theories of ageing are advanced in the literature a high proportion can be considered to be special cases of a previous hypothesis. No one individual theory satisfactorily explains the biological mechanism of ageing, indeed elements of many theories may be required to understand such a complex phenomena. Such a view has been formally expressed by Wright and Davison who consider that all theories represent too simplistic an approach to the understanding of ageing, a biochemical complexity which can only be resolved using system analysis techniques.