Aging: the loss of temporal organization.

Abstract

Aging, I am sure, has concerned man since first he realized that it happens to him. Since then he has attempted to avoid it, reverse it, and, to some degree, understand it. None of these efforts has thus far met with much success. By and large, aging is thought of in terms of the psychological, economic, social, and medical problems which it generates; it is thought of as being what it seems to create—especially what it seems to create in man. In my view, however, aging is first a biological problem because it is first a biological phenomenon. Biological organisms suffer a gradual decline in functional potential with advancing age. This decline is essentially linear and is accompanied by an exponentially increasing probability of death [i]. These senescent changes are manifest so dramatically that even the untrained eye does not confuse a man of sixty with a man of twenty-five. Nevertheless, little progress has been made in uncovering the causes or cause for these changes which so distinctly mark senescence in the biome. The notion that common effects arise from common causes, although intuitively derived, is one of the central tenets in gerontology. Clearly, neither this notion nor its converse is necessarily true, especially when applied to complex systems such as biological organisms. Yet, in spite of its doubtful foundation in logic, this truism remains clearly implicit in much of the current thinking in gerontology and in the experimental work generated by this thinking. But, as various levels of biological organization have been probed for possible causes of senescence, it has become increasingly difficult to discriminate between young and old.