Cunningham, Unisexual Inheritance. 35 



He next considers eye-colour from the same point of view, and 

 finds that there is a distinct difference of type between husbands and 

 men in general. There is also a difference in type but of less magni- 

 tude between wives and women in general. The general tendency is 

 for the lighter eyed to mate, the darker eyed being less frequently 

 married. Whether the fact is due to actual preference on the part of 

 the women is not certain, it may be due to greater philogamic in- 

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



In this case then more light-eyed men get married than dark 

 eyed men, and also more light eyed women than dark eyed women, 

 but the selection is greater among the men. But what Professor 

 Pearson does not discuss is the relation of these conclusions to the 

 sexual dimorphism. Are men lighter eyed than women in type? The 

 figures given show a considerable difference between the sexes in 

 this respect, and apparently it does consist in the men being lighter 

 in eye-colour. But what reason is there for supposing that the selection 

 for marriage of the lighter-eyed men would have any effect in making- 

 men on the average lighter-eyed than women? Again we find the 

 essential point ignored by Professor Pearson: sexual selection may 

 have been proved to be taking place, but what is the relation of this 

 selection to the sexual dimorphism? 



Professor Pearson next proceeds to discuss assortative mating 

 in mankind, and examines again the same two characters, namely, 

 stature and eye-colour. He finds that there is a quite sensible tendency 

 of like to mate with like, husband and wife are more alike for one 

 of these characters than uncle and niece, and for the other more alike 

 than first cousins. There is therefore according to this evidence, not 

 only no sexual selection in relation to stature, but actually a selection 

 in the opposite direction. Yet as I have already urged the difference 

 in stature is one of the most marked of the secondary sexual differences 

 in mankind. Professor Pearson's investigation with regard to this 

 point therefore goes to prove that the sexual dimorphism in this 

 character is not only not maintained by sexual selection or preferential 

 mating, but is maintained in direct opposition to assortative mating 

 which is the opposite of sexual selection in Darwin's sense. 



Professor Pearson also finds that a quite sensible measure of 

 homogamy or assortative mating exists with regard to eye-colour. This 

 seems to be in contradiction to his previous result that preferential 

 mating occurs in reference to this character. It is difficult to under- 

 stand how women can at the same time prefer men with the lightest 

 eyes, and those with eyes most like their own. The contradiction is 

 apparently explained by the fact that the lightest-eyed women are 

 also more frequently married. But it seems to me that if this is the 

 case sexual selection in Darwin's sense does not take place in 



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