ILLUSTRATION OF STATISTICAL RESULTS 333 



7. Illustration oj Results reached by Statistical Study 



While we can neither explain the methods nor summarise the 

 arguments, it may be permissible to cite some of the results 

 reached by the statistical study of inheritance, always bearing 

 in mind the caution that the validity of a statistical result, like 

 the validity of any other scientific result, depends on the value 

 of the data. The world of organisms is very large and hetero- 

 geneous, and results that hold good for certain forms of life may 

 not be true of others. 



It has been shown statistically that in the human race the 

 father is prepotent in the matter of stature, and this for offspring 

 of both sexes (Pearson). 



It has been shown statistically that a subtle quality like 

 fertility is a heritable quality, and more detailed statements 

 can be made e.g. that the woman inherits fertility equally 

 through the male and female lines. 



The immediate practical bearing of some of these researches 

 is evident. Thus Messrs. Rommel and Philipps (1906) have shown 

 in regard to Poland China hogs : (i) that there has been an 

 increase of "48 in the size of litter in the twenty years between 

 1882 and 1902, and (2) that the size of litter is a character trans- 

 mitted from mother to daughter. " It would appear proved 

 that, by judicious selection for breeding purposes of sows from 

 large litters, the average for the breed may be increased." 



Prof. Karl Pearson has been led by rigorous statistical methods 

 to statements like the following : 



" If selection were to act upon our 5' 9" Englishmen, and 

 the 6' among them were the type best fitted to survive, then 

 with fairly stringent selection it would not take more than six 

 generations to produce a type sensibly 6' high, and this type 

 would be permanently established even if selection ceased. ... 

 Our determination of the quantitative strength of heredity is 

 thus seen to give values quite intense enough to produce 



