Adaptation and Study of Ageing 61 



which may somehow remind us of what happens in later life 

 in degenerating cells, this is not true ageing : on the contrary, 

 these are processes of adaptation. 



When the newly born infant adapts itself to the completely 

 changed conditions of extra-uterine life, it acquires the 

 capacity of heat-regulation, of enteric nutrition, visual and 

 acoustic sensitivity and motor activities of increasing com- 

 plexity. Thus, it increases the range of its environment and 

 acquires more and more potentials to meet the constantly 

 changing conditions of life. Its evolution in the first years of 

 life is principally an increasing capacity for adaptation. 



The evolution of the individual's nervous system finally pro- 

 vides it with the capacity to live in the Arctic and in the 

 Tropics, at temperatures between —40° and 50° C, to live at 

 pressures between 150 mm. Hg and 5 atmospheres, to with- 

 stand dangerous radiations and to meet the psychical chal- 

 lenges of the business world or of the political world ; in other 

 words, it enables the growing individual to learn to adapt 

 himself to more and more difficult circumstances. 



These processes of adaptation produce a maximal capacity 

 and effectiveness in many or all the necessary organs. To 

 enable the individual to survive, his endocrine structure must 

 be normal, i.e. healthy, because endocrine hormones influence 

 the metabolic activities of muscles, of liver, of kidney and of 

 so many other cells. A lack of insulin will be as deleterious as 

 a lack of corticosteroids. A disharmony between the function 

 of all organs will be disastrous. If his kidneys cannot stand 

 periods of thirst, it will be as destructive for his life as if his 

 brain neglects to watch for his deadly enemy. Training of all 

 organs to almost — but not complete — maximal capacity goes 

 on throughout the years of extra-uterine life. This is adapta- 

 tion. 



In the young animal, adaptability overshoots its average 

 requirement to a point where large reserves of adaptation are 

 accumulated. Young animals "play" with the mother to 

 increase their forces for any possible emergencies. The 

 minute volume of the heart, the circulation blood volume, the 



