Adaptation and Study of Ageing 63 



In conditions of primitive life, he will now still be able to 

 recognize his neighbour in the cave, but he will not notice 

 until too late his enemies in the jungle. This is the same age 

 at which, in his female partner, ovulation ceases, and thus 

 both become superfluous for the upkeep of the race. From the 

 point of view of the race, they are aged. If we did not respect 

 in man the mental part of his life, we could rightly say that his 

 lifespan should end at the fiftieth year. It is only the mental 

 powers which have a continuing value with the prolongation 

 of his lifespan, and I think this provides an answer to the 

 question of ambition to prolong life. Individual mental 

 experience, and the capacity to transfer this experience, is the 

 only advantage of the prolongation of a man's lifetime, from 

 the point of view of the race. A specific human factor seems 

 to enter gerontology at this point. 



Thus, a decrease in the capacity for adaptation is the main 

 characteristic of ageing. If we try to understand ageing, we 

 should try to understand those changes which make adapta- 

 tion less possible. It would be naive to see the cause of 

 decreased adaptation only in apparent morphological changes. 

 It is true that these exist : for instance, the athletic capacity 

 of the young individual alters if his tendons and joints become 

 rigid. In this case, apparently macro- and microscopical tissue 

 changes seem to explain the decreased capacity, and the 

 problem is: "What causes the morphogenic changes?" But 

 adaptation is a dynamic process. The capacities to integrate 

 complex functions diminish, as shown by the following 

 examples : 



The capacity of heat regulation decreases with age (Hiigin 

 and Verzar, 1956a). This needs a central integration between 

 chemical and physical processes, i.e. heat production in 

 the muscle and heat release by conduction, radiation and 

 evaporation through a regulation of blood circulation and also 

 evaporation of water from the lung and skin. 



Both processes are decreased in the aged. Old rats 

 are unable to protect themselves against temperature de- 

 crease in a cold environment, and they are also less able to 



