BIOLOGY IN HUMAN AFFAIRS 



the business of alleviating sorrow, sickness, and mental 

 maladjustment is as momentous from the genetic point of 

 view as from the environmentalist point of view. But even 

 if this were not so, we should still have to face the facts. 

 And the facts are roughly these. Individuals, because of 

 their diverse gene patterns, exhibit marked differences in 

 aptitudes, temperaments, and all other varieties of mental 

 capacity. They have this groundwork laid down at the 

 very beginning of development; and it is altogether likely 

 that, owing to the rigidity of the environment entailed by 

 mammalian physiology, there is great constancy in the 

 unfolding processes which are carried on during the more 

 plastic period of the life history. At puberty, or a little 

 after, growth is finished; and the mind, as well as the 

 body, has reached the state of complete organization known 

 as maturity. But this does not mean that either the mind 

 or the body becomes rigid and inflexible. It may very well 

 be, as Watson claims, that, in a certain sense, the very 

 young child has no mind. It has merely a rather empty 

 brain which can be filled and its behavior conditioned by 

 what fills it. But the brains of children, like clay pots, are 

 of various sizes and qualities. What they will hold, and how 

 much, is largely determined by the genie materials which 

 went into them. 



Though to those who are familiar with modern genetic 

 data it is as redundant as two tails to a dog, direct evidence 

 exists on this very point. It is found in various statistical 

 studies of eminent men and their relatives, in studies of 

 identical twins, and in studies of intelligence by means of 

 psychological tests. 



Among the extensive studies of eminent men and their 

 relatives are those of Galton, De CandoUe, Ellis, Cattell, 

 and Woods. Naturally, such studies are full of pitfalls. It is 

 difficult to select a series of names for study in a wholly 

 objective manner; it is impossible to make accurate allow- 



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