Conclusion 



regulating operations in growth or development subsequent to 

 normal adulthood. The third possibility is that which is already, 

 and very justifiably, receiving the major part of the energy 

 devoted to clinical studies upon human ageing. The removal 

 of successive causes of death should in theory increase the specific 

 age. It is interesting to notice that there is so far very little 

 evidence of such an effect. It was once widely believed that 

 with the removal of 'pathological' causes of death the specific 

 age would rise very rapidly in man and approach the recorded 

 maximum. Although research on the diseases of later life has 

 not yet had time to reach a stature comparable with the life- 

 saving powers of surgery and epidemiology in early life, it 

 seems possible that even with increased control over neoplasms 

 and cardiovascular disease the age at death might only come 

 to be more and more normally distributed about the present 

 specific age. Most people who die in old age are found at post- 

 mortem to have several further pathological processes at work, 

 beside the one from which they died. If an arbitrary normal 

 distribution of deaths due to 'pure' senescence were assumed, 

 the shape of the curve could be inferred from the shape of that 

 one-half of the existing, positively-skew curve which lies between 

 the ages of 75 and 100. Such an assumption may well, however, 

 be false. The smoothness of the curve between those ages is 

 largely due to manipulation by actuaries, relying on a conven- 

 tional end to the human survival curve to help them over 

 statistically insignificant material (Freudenberg, 1949). We 

 have not reached the limits of the purely prosthetic and sup- 

 portive treatment of senility, and we are unlikely to do so for 

 a very long time. 



There remains the possibility of prolonging life by slowing 

 down the movement of the developmental programme. Such 

 slowing, to be of medical interest, must be compatible with 

 retention of normal vigour and activity. The mere duration of 

 individual existence could quite possibly be extended, as John 

 Hunter proposed, by some form of artificial hibernation, 

 punctuated by periods of activity: but this possibility is more 

 interesting to stockbreeders, astronauts and perhaps politicians 

 than to gerontologists. The prolongation of infancy is unlikely 

 to be of much interest, unless it is indispensable to some effect 

 o 195 



