This hypothesis, which has recently been discussed by Swanton,[38-v] was already advanced only to be proved inadequate by Morgan himself. Taking the Seneca for illustration, where descent is in the maternal line, Morgan shows that the children of two sisters would indeed be members of the same clan and hence clan brothers and sisters but that this explanation no longer holds for the children of two brothers. By the law of exogamy these would be required to marry into another clan and there is no reason why their wives should belong to the same clan. Hence the brothers’ children will not be clan brothers and sisters, yet, according to Seneca terminology, the offspring of brothers no less than of sisters are classed with own brothers and sisters. Accordingly, the clan system—though it has a definite place in Morgan’s scheme of evolution—is not regarded by him as the determining factor of the Seneca-Dakota principle.[39-v]
But the objection vanishes if we accept the theory that the Dakota principle arose as a reflection not of a multiple clan system but of an organization with exogamous moieties. This theory, which to my knowledge was first developed by Tylor[40-v] and has since been advocated by Rivers,[41-v] has obvious advantages. Even on the simple clan hypothesis it is clear why the father’s brothers should be classed with the father and separated from the maternal uncles, since the latter by exogamy must belong to a different clan. The term which we translate ‘father’ would really be seen to mean ‘male member of the father’s clan and generation’. With the moiety theory the same facts are explained, but also in addition the designations for other relatives. To take again the Seneca instance, the sons of two brothers must be members of the same social division because with a dual organization the brothers are restricted to the same division in the choice of a mate; hence it is quite natural that the sons of brothers should call one another brothers. Again, the difference between parallel cousins and cross-cousins is perfectly intelligible. The mother’s brother’s and the father’s sister’s son can never be of my moiety; if descent is matrilineal they belong to my father’s moiety, if patrilineal to my mother’s. Hence it is natural that they should not be classed with my brothers who in either case are my moiety-mates. This hypothesis also explains features not yet referred to, but often found in conjunction with those grouped under the heading of the Dakota principle, e. g., the frequent classification of the father’s sister’s husband with the maternal uncle. Given exogamous moieties, these relatives must belong to the same half of society, to my own moiety if descent is maternal, to my mother’s if it is patrilineal. The Tylor-Rivers theory thus explains very satisfactorily the rather numerous features that jointly constitute what I have called the Dakota principle; we can at once see that here is not an arbitrary rule of classification but a definite rationale.
However, it is worth noting that while the moiety theory explains a number of traits better and more simply than the hypothesis of multiple clans or gentes of which it is a special form, the latter is not in so bad a plight as Morgan would have us believe. That I should call my father’s brothers and male cousins of the paternal line ‘father’ and my mother’s sisters and female cousins of the female line ‘mother’, follows from the general hypothesis of exogamy no less than from the moiety theory. The difficulty urged is the grouping together of brothers’ sons who are not clansmen under a matrilineal organization with sisters’ sons who are. But all terms of relationship are correlative: the concept of elder brother is meaningless without the correlated concept of younger brother; so the very fact that I address my father’s brother as ‘father’ has as a necessary consequence that he should address me as ‘son’ regardless of whether his own son is in my clan. Similarly, the fact that my father’s brother’s son and I both address my own father as father makes us brothers irrespective of clan affiliation. Clan affiliation is still the primary determinant since it fixes the connotation of the word translated ‘father’, while the other usages mentioned are derivative applications. The objection that naturally obtrudes itself is why the term for father should be taken as the starting-point rather than that for son or brother. The answer lies in the fact that in a number of instances the term for father has an emphatically clan or gentile significance, being extended even to father’s clansmen of the speaker’s generation, as among the Crow and Arizona Tewa. Nevertheless, it cannot be denied that from the point of view of summarizing the data comprised under the caption of ‘Dakota principle’ or intimately linked with them the moiety theory is distinctly superior. Thus, the union of father’s sister’s husband and mother’s brother under a single head does not follow from a multiple clan or gentile organization but is intelligible on the basis of a dual division.
The weakness of the moiety theory lies in another direction. In order that the dual organization may fashion kinship nomenclature, it must of course exist. Now it does occur in Australia and Melanesia, though not universally, and in part of North America, but it is lacking in many regions of this continent and, so far as I know, in Africa. If we derive the Dakota principle exclusively from the dual organization we are therefore obliged to assume either that this institution once had a far wider range of distribution or that the nomenclature it produced traveled independently of the moieties to a considerable number of other peoples. This is a difficulty that must be frankly recognized.
In this regard the exogamy hypothesis in the broader sense enjoys an obvious superiority. Exogamous kin groups occur both in southern Africa and in many sections of America from which exogamous moieties have never been reported. Doubtless here, too, we must reckon to a considerable extent with the effect of diffusion, which repeatedly carried the Dakota principle to non-exogamous tribes. Yet when we apply the method of variation to the best-studied regions of the globe, our confidence in the essential correctness of the exogamy hypothesis is considerably strengthened. In Oceania it is the non-exogamous Polynesians who fail to distinguish the maternal and paternal sides, while the generally exogamous Melanesians recognize the principle of bifurcation. In North America, the non-exogamous tribes are either bifurcating but fail to merge the collateral and lineal lines or neither bifurcate nor merge.[42-v]
Certain instances are especially illuminating because they permit a refinement of the method of variation by the practical or total elimination of other factors to account for the phenomena. Thus on the northwest coast of America we find certain tribes like the Kwakiutl and Nootka who are not organized in strictly exogamous groups, and here neither merging nor bifurcation occurs. “The terms for ‘uncle’ and ‘aunt’ refer equally to the father’s and mother’s fraternity;” and specific terms distinguish father and mother from more remote kindred. When we compare such systems with those of the more northern and exogamous tribes, viz., the Tsimshian, Haida and Tlingit, we discover at once a striking difference. In all these terminologies men of the father’s are distinguished from those of the mother’s moiety or clan; and the collateral lines are wholly, or almost entirely, merged in the lineal lines.[43-v] Here we are not dealing simply with a contact phenomenon, for no good reason can be given why the Tlingit system should not have extended southward or the Kwakiutl system to the north. Nor are we simply confronted by a difference of tribal affiliation: while the Kwakiutl and Nootka belong to the same stock, and affinity has recently been claimed for the Tlingit and Haida languages, the Tsimshian stand apart. It is the difference in social organization that runs parallel with the difference in nomenclature.
A similar case is afforded by the Shoshonean stock. Within this family specific terms for father and mother as opposed to uncles and aunts are the rule and cross-cousins are generally not distinguished from parallel cousins and brothers. There is thus a combination of extreme Hawaiian inclusiveness in the speaker’s generation with the tendency to non-classificatory nomenclature in the first ascending generation. But among the Hopi, the only member of the group organized into exogamous clans, the Dakota principle holds sway. Since no Southwestern system is known that so clearly reveals the forked and merging principle, the possibility of borrowing seems barred and we have proof of the independent evolution of this feature in correlation with a clan system.
So far, then, as the distribution of the Dakota principle over discontinuous regions of the globe is concerned, the hypothesis of exogamy gives a reasonably satisfactory explanation of the facts, while within each continuous area we shall assume a greater or lesser degree of dissemination. Applying this, e. g., to the Northwestern Indians as a whole, we shall indeed regard the evolution of Dakota features as a response to the exogamous organization, but when we turn to the three exogamous tribes individually, we shall face the problem whether the terminology did not spread from one tribe to its two neighbors. It is quite true that theoretically there is the possibility that the clan system, not the terminology, was the diffused feature and that the organization in each case independently produced an appropriate nomenclature. However, we have undoubted instances in which features of nomenclature were not associated with any social institution, indeed, where the very words have been borrowed. Further the development of an appropriate terminology is not an absolutely automatic process, as is shown by the failure of some tribes with exogamy to develop one. Hence it seems probable that within a limited continuous area the Dakota principle developed only once and then spread to neighboring tribes. That the existence of an exogamous organization among the borrowers would be a favorable condition for the adoption of the nomenclature is obvious, also that the organization and the terminology may be borrowed jointly.
In order to strengthen the case for the exogamous theory it is necessary to show that the same results could not be accomplished, or not so well, by other conditions of equally wide distribution. As a matter of fact, an alternative interpretation has recently been advanced.[44-v] In the case of the non-exogamous Californian Yahi Dr. Sapir connects the merging of lineal and collateral lines with the marriage regulations obtaining there and suggests that these rules “may no doubt not infrequently be examined as an equally or more plausible determining influence”. The practices referred to comprise the levirate, i.e., a man’s marriage with his brother’s widow, and marriage with the deceased wife’s sister. (Why, deceased? we may well ask Dr. Sapir, since a man’s preëmptive right to his wife’s younger sisters is a widespread custom in North America.)
I do not doubt for a moment that the customs in question have affected kinship nomenclature, but I seriously question whether they constitute an adequate substitute for exogamy as an interpretation of the empirical distribution of the Dakota principle. The levirate, it is true, is an exceedingly widespread institution: Tylor found it among one hundred and twenty out of some three hundred peoples.[45-v] But the levirate alone will not do since it only explains the extension of the father term to the father’s brother and the correlative extension of the term ‘son’ to the brother’s son (man speaking). It remains to be seen, therefore, to what extent the levirate is united in different regions of the globe with the usage of marrying two or more sisters, which would further explain the classification of mother’s sister with mother and of the sister’s children with the children (woman speaking). So far as I know, the range of the two usages jointly has not been ascertained; pending its determination, the distribution of the Dakota principle is not accounted for, as it approximately is by exogamy.