Data for the Frohlcm of Evolution in Man. 27 



This table shows us the decrease of variability with age in botli 

 weight and height. But the female is now more variable than the 

 male. Were this change to be attributed to natural selection, with a 

 stronger incidence on the male than the female, then we have the 

 anomaly that the correlation has been reduced in the male, but increased 

 in the female, while theoretical considerations would lead us to the 

 conclusion that it ought to be reduced in both. We are compelled to 

 consider the changes in variation and correlation as due to growth or 

 nurture ; or, if there be selection, it is to a large extent screened 1 )y 

 these causes. 



V. — Correlation between Height, Weight, and Strength of Pull. 

 (Data for 1000 Males and 160 Females.) 



Females . , 

 Males .... 



Organs. 



Coefficient of correlation. 



\ Strength of pull f 

 J and height \ 



0-216 ± 0-052 

 0-303 ± 0-019 



Females ., 

 Males .... 



\ Strength of pull f 

 J and weight \ 



0-338 ± 0-049 

 0-545 ± 0-015 



I expect the greater correlation of the male in these tAvo cases is due- 

 to the fact that a better physical training has taught him how to 

 make use of his height and weight, especially the latter, in exerting his 

 strength. 



VI. — Correlation between Height, Weight, Strength of Pull, and Head 

 Index. (Data for 1000 Males only.) 



Organs. 



Coefficient of correlation. 





-0-082 ± 0-021 





0-011 ± 0-021 



Strength of pull and head index 



0*041 ± 0-021 



Thus it is only in the first case that the correlation with head index 

 can be considered as significant, and in this case it is negative. There 

 is no reason, then, for supposing brachycephalic persons stronger of 

 heavier than dolichocephalic, but they do appear to be slightly 

 shorter. We conclude, therefore, that dolichocephalic persons (? races) 



