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CHANGES WITH AGING 

 Ancel Keys 



UNIVERSITY OF MINNESOTA 



This symposium on Growth began with consideration of the most ele- 

 mentary aspects— the synthesis of nucleic acids and proteins. It is fitting 

 to end, as we do tonight, by discussing aging, or, if you will, the later 

 stages of growth. 



Emotionally we distinguish growth and aging as opposites. In 

 value terms, growth is good, aging is not good— or, in positive language, 

 it is "evil." The relative amount of research activity on the two subjects 

 is possibly explained by this subconscious association. I am reminded 

 of the medieval philosophers who agreed that God and the Devil were 

 complementary and equally complex but who then devoted far more 

 scholarship to God than to the Devil. 



I do not propose to be the Devil's advocate, but perhaps my dis- 

 cussion can be viewed as a consideration of his evil works, as exhibited 

 in the biological changes associated with aging. Mind you, I am not 

 prepared to specify what should actually be called aging, much less to 

 say what causes it. 



An easy and not very illuminating definition of aging is that it is 

 the process in which characteristics of an organism change progres- 

 sively with time. Growth and aging are, in many respects, merely dif- 

 ferent terms to describe progressive biological changes along the time 

 axis. Degenerative changes, identifiable as some kind of aging, ac- 

 company growth from the very beginning. And, similarly, growth, in 

 the sense of the accretion of some substances in the body, is a part of 

 aging. 



Figure I illustrates the point by the example of the amount of 

 cholesterol and of calcium in the human aorta. From age 10 to age 70 



* I am grateful to Mr. Juakko K. KiJil})cr^ for his Itclp witli sonic of the 

 ■statistical work reported here. 



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