PROBLEMS OF HUMAN EVOLUTION 



may have been jealous ; but stature is no proof of stamina. 

 At the same time it must be remembered that tallness is relative : 

 a tall Siamese would not be tall for a Scotchman. It is over- 

 elongation, beyond the height proper to the race, that is often 

 found to bring weakness with it. 



Thus in some cases great height may be a symptom of de- 

 generacy. It may result from the softening of the conditions of 

 life, that allows weakness in various forms to survive. Assuming 

 that the standard of height has risen within recent years in the 

 upper classes and there seems to be reason to believe that this 

 is so we must attribute it to the bettering of the environment. 

 Certainly there has been no increased stringency of Natural 

 Selection eliminating persons of smaller build. And these two 

 are the only possible explanations. There is no third alternative. 

 Repro- For Professor Karl Pearson's Reproductive Selection, though it 

 selection* pl avs a verv important part, cannot have the effect upon stature 

 supposed that he claims for it. 1 If it can be shown, he argues, that any 

 eCt s tat P ure character is correlated with fertility, that character will develop 

 progressively quite apart from Natural Selection. Statistics 

 founded upon observations on four thousand families chiefly of 

 Anglo-Saxon race and one thousand eight hundred and forty-two 

 of Danish race would lead to the conclusion that there is " a 

 sensible correlation between fertility and height in the mothers 

 of daughters." From this, he infers, that independently of 

 Natural Selection there must be a continuous increase in the 

 mean height of women. In forty generations (one thousand 

 years) it would be raised 3^ inches. " Reproductive selection 

 at anyrate in civilised man seems a factor of evolution equipotent 

 to Natural Selection, if indeed it be not prepotent." 



Here is an attempt to dethrone Natural Selection and put 

 it in a subordinate position. But Natural Selection, if it really 

 is the regulating principle of evolution, must dominate all other 

 tendencies. From its very nature it cannot tolerate a rival. In 

 the present instance it is easy to make this clear. There are, 

 broadly speaking, four possibilities only to be considered (l) 

 fertility correlated with fitness in the offspring to survive ; (2) 



1 Natural Science, May 1896. 



