ASSORT ATIVE MATING IN MEN 487 



justice points out that his data for stature were taken largely from the 

 professional classes — chiefly residents of London and other larger towns. 

 Wliile these marry in their own " sets," these can hardly be regarded as 

 " local races." The records from cemeteries, to be discussed in the 

 following section, were taken purposely from narrowly limited districts ; 

 tables were formed for each locality separately. Certainly such correla- 

 tions can not be attributed to the heterogeneity arising from the mixing 

 of differentiated samples. In other cases, the possible influence of local 

 races has been well excluded. 



Even if the demonstrated resemblances were due merely to the 

 tendency to marry within the local race, and indicated no conscious or 

 unconscious sexual selection on the part of individuals of the same race, 

 they would nevertheless be of great interest as showing quantitatively 

 the force of one of the factors tending to maintain racial boundaries. 



III. ASSORTATIVE MATING FOR DURATION OF LiFE 



That human matings should so depend upon the visible physical and 

 intangible, but none the less real, psychical characteristics as to give 

 rise to a measurable bodily and mental similarity of spouses, while con- 

 trary to popular belief, seems not unreasonable. That this resemblance 

 should extend to duration of life — a character quite unknowable at the 

 time of marriage — appears at first thought highly improbable. 



But duration of life is not a simple attribute. It is rather a con- 

 veniently measurable epitome of many physical and physiological traits, 

 as well as of environmental conditions. Both its inheritance and the 

 evidences which it furnishes of the action of natural selection in man 

 probably depend upon its being the resultant of a complex of factors. 

 May not assortative mating for appreciable personal characters result 

 in an assortative mating for duration of life ? 



The answer given by the correlation between the age at death of 

 husband and wife (Table V.) is affirmative — clear and emphatic. 



TABLE V 



Number of Coefficient of 



Source of Material Pairs Correlation Measuring 



Wenslevdale and district cemeteries 876 -+- .2200 it .0244 



Oxfords'hire cemeteries 890 + .2500 =b .0211 



Society of Friends' records 1,000 +.1999±.0212 



Mean .2233 



Warren, Pearson, Lutz, Lee and others^^ drew their records from the 

 tombstones of rural English churchyards and from the archives of the 

 Society of Friends — two quite dissimilar sources. Yet the results are 

 in remarkable agreement; considering the errors common to statistical 

 constants based on numbers of a thousand or less, one can not assert 



^ ' ' Assortative Mating in Man : A Cooperative Study, ' ' BiometriTca, Vol. 2, 

 pp. 481-498, 1903. 



