James Arthur Harris

“ The precise meaning of the term "assortative mating" may perhaps be made a little clearer in the process of explaining how the similarity or dissimilarity of husband and wife is measured.
Suppose a most highly refined socialistic community should set about to equalize as nearly as possible not only men's labor and their recompense, but the quality of their wives. It would never do to allow individuals to select their own partners—superior cunning might result in some having mates above the average desirability, which would be socially unfair! ”

“ Pearson has warned us that "in many factors there may actually be two opposed currents, one giving a tendency for like to mate with like and the other marked by the fascination of extremes." Goring's studies of criminals vindicate one's a priori conviction that assortative mating may be influenced by social conditions. Human society differs so profoundly from place to place and time to time that, however great the temptation to generalization may be, it would be folly to press the conclusions far beyond the data which they represent. ”

“ Probably assortative mating for deafness is more nearly perfect than that for any other known character. The reasons for this are patent. Hearing individuals rarely choose non-hearing mates. When both partners are deaf, on the other hand, they are united by the strong bond of fellowship and sympathy growing out of their similar condition, they communicate with each other with perfect ease and freedom, and the social interests and sympathies outside their own home are the same. ”

“ To determine whether men and women tend to parity or disparity in matrimonial choice, we must, therefore, take a large number of mated pairs at random from the general population, sort them into groups according to some characteristic—quantitatively measurable whenever possible—and determine by means of the statistician's coefficient of correlation whether generally similar or dissimilar groups of men and women tend to mate, and how strong this tendency to parity or disparity is. Throughout this paper the intensity of assortative mating will be expressed by the coefficient of correlation. ”

“ But if sexual selection be a real factor in the evolution of races—in the differentiation of groups as well as in their maintenance—its action must be sought within the race, an intra-racial sexual selection must be demonstrated.
Sexual selection in man may, as Pearson long ago pointed out, [3] be of two kinds, preferential mating and assortative mating. By preferential mating one understands that certain classes of women are discriminated against by the average man, or by men as a class, or vice versa. ”

“ The correlation really found was sensibly zero, demonstrating that local environmental conditions can not explain the results.
But within the same general environment, members of a family are exposed to a set of conditions peculiar to themselves. In a city block or country parish food, temperance, sanitation, risk of zymotic disease, and physical and mental habits differ greatly from family to family. In addition to the physical and social environment common to man and wife, there is also the fact that the death of one member of the pair has a profound effect on the other. ”

“ But duration of life is not a simple attribute. It is rather a conveniently 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. ”

“ Even in countries which pride themselves on the absence of social strata, wealth, family pride and feuds, religion and education, play their part in limiting the range of choice in marriage selection. But nowhere is mating within the class universal. ”

“ The much-multiplied American dollar plays havoc with continental pedigrees. The pure breeding of the English nobility is a pretence; "the lawyer, the farmer, the silk mercer lies perdu under the coronet, and winks to the antiquary to say nothing." Some day the weight of these social forces will be determined, but the proper kinds of facts are not yet available. ”

“ To-day, an unfortunately insistent demand that every datum must count for or against some current theory has largely replaced the Darwinian spirit of collecting facts in the hope that when sound and sufficiently numerous, reasonable theories may be fitted to them. To-day "a fact is not a fact until it fits a theory." ”

“ When we consider that in the general population of the United States there are roundly 1,500 hearing persons to one deaf, and consequently about 1,500 hearing persons to one deaf from whom a given deaf individual might seek to select a life partner, we see to what enormous extent sexual selection is at work for this character. ”

“ Duration of life is doubtless dependent upon environment as well as upon constitution. Slight differences in the healthfulness of the several parishes of a district might promote or oppose fullness of years in men and women alike. If this were true, the lumping together of the records from a number of churchyards would result in a correlation for duration of life, whether there be any real assortative mating or not. ”

“ Normal individuals discriminate against deaf mutes, for obvious reasons. There is a stringent segregation of the class, resulting from educational and social conditions, and as a result there is for the people, as a whole, a strong assortative mating, hearing people as a class marrying hearing, and deaf marrying deaf. ”

“ Some have even ventured the opinion that where the husband and wife are unlike, the offspring are more numerous, or stronger! Again there is the popular superstition that after a long life together husband and wife come to resemble each other physically. ”

“ 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. ”

“ These give results which vary widely among themselves and if one takes those which seem the most likely to be trustworthily determined, he opens himself to the criticism of the selection of evidence. Personally, I have grave doubts concerning the value of data on psychical characters collected by the widespread circulation of schedules. The estimates are too much subject to personal equation and family bias. When they are entrusted to especially trained observers who work comparatively, the ease is better. ”

“ From the notion that in marriage "opposite poles attract" the step to the conclusion that dissimilar are more fertile than similar unions is so easy that it has sometimes been taken, though without any valid evidence in justification. ”

“ Exalted as they were on comparative evidence alone, and by post-Darwinian enthusiasts who were not only fertile, but liberal to a fault, in assumption, their debasement was inevitable. We are now in the period of reaction when men disparage selection, or dismiss it entirely as an evolutionary factor. ”

“ However strenuously the biologist may deny validity to the element of artificial selection among the lower animals, it certainly plays a large part in influencing sexual choice among primitive men and more subtly among us in civilization. ”

“ Alcoholism is one of those interesting cases in which direct personal or social influence may supplement and reinforce the resemblance possibly due to assortative mating. Goring, [48] dividing his material for English criminals [49] into three classes for social status, finds these coefficients of resemblance:
For criminality, Goring's results will strike many as surprisingly low. ”

“ However much popular opinion may overestimate women 's reticence concerning their ages, statisticians know that even the correct age of marriage of both men and women is hard to obtain. Especial difficulty is to be expected near the extremes of the series. Those embarrassed by years may declare themselves of legal age, or even deduct a few years. Those who are not yet of legal age may falsify to obtain a license. ”

“ Considering the intensity of the inheritance of deafness, [32] we see what grave social results may be expected from this tendency.
Apparently unions where both members are deaf are more happy than those where only one is so afflicted. ”

“ The method adopted would be to write the names of an equal number of men and women officially condemned to matrimony on cards, and to place those for men in one lottery wheel and those for women in another. ”

“ Data for physical characters other than stature are few; [19] the only important ones are forearm and span in Pearson's investigation. [20] For the direct [21] comparisons the resemblance is quite material, amounting to about + .200. Cross correlations are in general somewhat lower. Possibly the assortative mating is primarily for stature, while the resemblance for forearm and span arise merely because these are closely associated with stature. ”

“ The other extreme would be the state of affairs in which men of a certain type (that is to say men differing from the general average by a definite amount) always chose wives of a definite type; the resemblance would then be perfect and the correlation, as we call it, would be expressed by a coefficient of 1. ”

“ The strongest arguments are those of quantitatively expressed facts. The best way of overcoming the prejudices and other obstacles against which the biometrician works is to allow these facts to speak for themselves, if possible in terms comprehensible to the layman. ”

“ Weak or little men have a decided inclination for strong or big women, and strong or big women for weak or little men. Blondes prefer dark persons or brunettes; snub-nosed, hook-nosed; persons with excessively thin long bodies and limbs those who are stumpy and short, and so on! ”

“ Nevertheless, one cannot but be impressed with the intensity of the assortative mating that occurs independent of this factor. With no such isolation 62 per cent, of deaf individuals marry those who are deaf. ”

“ Fay also finds that of the pupils who attended exclusively oral schools 78.2 per cent, married deaf partners, while of those who were educated at schools not exclusively oral, or partly at schools exclusively oral and partly at schools not exclusively oral, somewhat over 86 per cent, of marriages were homogamous for deafness. ”

“ Moreover, if the biometric results reviewed in the preceding pages must be fitted post haste into some evolutionary scheme, or find an immediate practical social application, each reader must be responsible for his own. The difficulties of interpretation are even greater than the dangers of generalization. ”

“ The statistical facts reviewed in this essay make it highly probable that a great variety of physical and mental characters influence human matings, and in such a way that, on the average, similar individuals tend to marry. ”