Introduction and Historical 



merits that 'senescence is no more than the later stage of 

 embryology' resemble Benjamin Rush's great discovery, 

 that all disease is disordered function. They belong to the 

 category of word-rearrangement games, which have long been 

 played in those fields of study where there is as yet no 'hard 

 news'. 



Although the religious, poetic, metaphysical and philo- 

 sophical literatures of senescence will not be examined here, the 

 detection and examination of analogies based upon them, 

 which have had a great, and generally adverse, influence on the 

 growth of our knowledge of age processes, must clearly play a 

 large part in any critical examination of the subject. The com- 

 ments of Francis Bacon, who was both a philosophical originator 

 of the scientific method, and the first systematic English geronto- 

 logist, 1 provide one of the best critiques of the influence of such 

 analogies and thought-patterns, and they will be quoted without 

 scruple here. 



The practical importance of work upon the biology of 

 senescence, beyond the fundamental information which such 

 work might give about the mechanisms of cell differentiation and 

 renewal, can best be seen from the diagrams at Fig. 1-3 and 7. 

 The advance of public health has produced a conspicuous shift 

 in the shape of the survival curve in man so far as the privileged 

 countries are concerned, from the oblique to the rectangular 

 form. This has been due almost entirely to a reduction in the 

 mortality of the younger age groups — the human 'specific age' 

 and the maximum life-span have not been appreciably altered. 

 The medical importance of work on the nature of ageing lies at 

 present less in the immediate prospect of spectacular interfer- 

 ence with the process of senescence than in the fact that unless 

 we understand old age we cannot treat its diseases or palliate 

 its unpleasantness. At present age-linked diseases are coming to 

 account for well over half the major clinical material in any 

 Western medical practice. The physician is constantly referring 

 to the biologist for a scientific basis for geriatrics, and finding 



1 I dislike this word, but it is probably too well grown for eradication. 

 It should mean 'a student of old men' (yegcov) and gerontology the study 

 of old men. For the study of age itself, the subject of this book, we require 

 geratology (yfjQag), upon which it would be fruitless to insist. 

 B 3 



