136 RETROGRESSION 



unmistakable. Besides the data which each person is able to verify 

 for himself, and which therefore is especially valuable scientifically 

 to him, a vast volume of very precise and detailed statistical infor- 

 mation relating to almost every human race and disease has been 

 published by all the Departments of Public Health in both hemi- 

 spheres. Presumably, if selection followed by evolution occurs 

 amongst men, it occurs amongst plants and lower animals. At 

 any rate, if it occurs amongst men, the inference that it occurs and 

 has occurred amongst other species is at least as likely to be true 

 as if drawn from a demonstration of its occurrence amongst some 

 other type of animal or plant. 



227. Such, however, has been the passion for obscured facts 

 that this patent evidence has been ignored. Laborious laboratory 

 inquiries which extended over several years have been undertaken 

 to demonstrate the actual occurrence of Natural Selection. 

 Doubtless they satisfied the workers, but they were declared by 

 opponents to be invalid on the ground that natural conditions 

 were not accurately reproduced. Even by adherents of Natural 

 Selection they are declared to be "at present not absolutely 

 convincing." * Of all the statistical evidence, the best is thought 

 to be that collected by Bumpus in America. 2 After a severe snow- 

 storm one hundred and thirty-six stricken sparrows were gathered, 

 of which seventy-two revived, while sixty-four perished. Bumpus, 

 after making careful measurements, concluded that " Natural 

 Selection is most destructive to those birds which have departed 

 most from the ideal type, and its activity raises the general standard 

 of excellence by favouring those birds which approach the structural 

 ideal." What precisely is the structural ideal is of course a matter 

 of opinion. It is at least possible that the birds which survived 

 possessed a superior power of resisting cold and hardship, and that 

 this power is not correlated to any of the dimensions length of 

 head, beak, and so forth that Bumpus was able to measure. 

 Compare the volume, precision, and relevancy of this evidence with 

 that concerning disease gathered by simple observation, and more 

 especially with that stored by Departments of Public Health. 

 Compare also the relative difficulty of demonstrating the connec- 

 tion between cause and effect in the two instances. 



228. Biometricians have also sought to demonstrate that human 

 mental ' ability ' and powers of resisting disease are * inheritable.' 

 They admit that the human species has arisen by evolution from 



1 Vernon, Variations in Animals and Plants, p. 337. 

 * Biological Lectures, p. 211. 



