HUMAN LIFE 



fidently to make statements about the 

 heredity mechanism and behavior really 

 startling in their preciseness and practical 

 importance. We can make enough proph- 

 ecies about the outcome of many cases 

 of mating to give us sufficient basis to 

 warrant us in modifying our social in- 

 heritance in directions to increase ad- 

 vantages or decrease disadvantages de- 

 rived from biological inheritance. 



Before Mendel and the post-Mendel- 

 ians, about the only so-called law of 

 heredity that had been formulated was 

 Galton's generalization to the effect that 

 an individual receives one-half of his 

 inheritance from his two parents, one- 

 fourth from his four grandparents, one- 

 eighth from his eight great grandparents, 

 one-sixteenth from his sixteen great, 

 great grandparents and so on by de- 

 creasing fractions back to the beginning 

 of ancestors, the total of these fractions 

 equalling 1, or the total biological inheri- 

 tance of the individual. Very interesting, 

 but not very specific as to just what 

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