382 THE STUDY OF ANIMAL LIFE CHAP, xix 



" Fathers of a given height have not sons all of a given height, 

 but an array of sons of a mean height different from that of the 

 father and nearer to the mean height of sons in general. Thus 

 take fathers of stature 72 in., the mean height of their sons is 

 70 '8 in., or we have a regression towards the mean of the general 

 population. On the other hand, fathers with a mean height of 

 06 in. give a group of sons of mean height 68 '3 in., or they have 

 progressed towards the mean of the general population of sons. 

 The father with a great excess of the character contributes sons 

 with an excess, but a less excess of it ; the father with a great 

 defect of the character contributes sons with a defect, but less 

 defect of it. The general result is a sensible stability of type and 

 variation from generation to generation." 



It must be understood, however, that these statistical 

 generalisations are average statements for fraternities, 

 not physiological conclusions relating to individuals. 

 They do not apply to lineages where there has been close 

 and consistent selection. They do not apply to the in- 

 heritance of Mendelian " unit characters." Nor do they 

 take sufficient account of the important fact that resem- 

 blances arc in part due to similar nurture, not wholly to 

 inheritance of similar inborn characters. 



It may be useful to keep the term " social heritage ' 

 for what is supremely important in mankind, the regis- 

 tration of experience and achievements which is effected 

 by tradition and custom, by institutions and laws, by 

 literature and art. For these bulk largely in the deter- 

 mination of human life. 



