THE BIOLOGICAL APPROACH IN THE 

 COMPARATIVE STUDY OF AGEING 



A. Comfort* 



Department of Zoology, University College, London 



The study of senescence deals with the processes which 

 make some organisms decline in vigour with increasing age. 

 It embraces a group of deteriorative effects which we isolate 

 because they are deteriorative, in other words because we dis- 

 like and wish to avoid them, and we undertake it with refer- 

 ence to the senescence of one organism, man, whose rate of 

 ageing it is our object to control. 



Fields of study in medical biology usually define themselves 

 in this way, but as a rule the processes which we originally 

 treat together for our own convenience prove later to have 

 some biological unity apart from their interest to man. We 

 normally assume the possibility of some such unity in any 

 study of this kind; much of the information upon which we 

 form hypotheses, and, very often, all or almost all the con- 

 trolled experiments by which we test them, come from examina- 

 tion of apparently analogous processes in animals. 



The cephalopod eye bears a strong superficial likeness to the 

 human eye, and one might learn something of the biology of 

 sight in man by studying it, but since its anatomy and chem- 

 istry are in fact quite different from those of mammalian eyes, 

 the amount that we are informed or misled by it will depend 

 entirely on the intelligence with which we make use of com- 

 parative study. The progress of endocrinology was held up for 

 years by attempts to identify menstrual phenomena in 

 animals which did not menstruate. 



In discussions of this kind it always falls to biologists to 

 irritate their colleagues by pointing out the diversity of 



* Nuffield Research Fellow. 

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