428 THE GRAMMAR OF SCIENCE 



Type. Variability. 



Husbands .... -435 ±-033 1.240 + .019 



Males in general . . . .565 + .014 1.3171.008 



Wives ..... .763 + .036 1.347 + .020 



Females in general . . . .825 +.01 5 1.329 + .008 



Difference in type between husbands and males = - . i 30 ± .036 



,, variability „ ,, = -.077 + .021 



,, type between wives and females = — .062 + .039 



„ variability ,, ,, =+.018 + . 022 



Here we see that in the case of husbands and males 

 the probable error of the difference is less than a third of 

 the difference in both type and variability-; that in the 

 case of wives the probable error of the difference is con- 

 siderably less than the difference in the type, but greater 

 than the difference in the variability. Accordingly we 

 conclude that in mankind there certainly exists a pre- 

 ferential mating in the matter of eye-colour, or of some 

 closely allied character in the male ; in the case of the 

 female there also appears to be some change of type due 

 to preferential mating, the variability, however, is not 

 sensibly changed. The general tendency is for the 

 lighter-eyed to mate, the darker -eyed being relatively 

 less frequently mated. What I have dealt with here is 

 really an illustration of method ; we require careful 

 measurements and investigations for other characters and 

 organs. But in the light of this illustration, I do not 

 think it can be doubted that sexual selection in the form 

 of preferential mating is not a mere hypothesis, but can 

 be demonstrated to actually exist in the case of man. 

 Whether it is due to actual preference on the part of the 

 women may, of course, be called in question. It may 

 possibly be accounted for by greater philogamic instincts 

 on the part of the blonde section of the population. But 

 such an explanation does not in the least destroy the 

 validity of the demonstration of the existence of pre- 

 ferential mating in man ; whether the^ preference arises 

 from greater sex -instinct or from aesthetic sense is 

 immaterial from the standpoint of evolution, however 

 interesting from the moral or the social standpoint. 



