Exogamy

“ Such transitions to the succeeding form of exogamy are to be found, for example, among the Australian Dieri, some of whose totem groups intermarry, only with some one particular group of the other tribal division.
The second form of exogamy occurs when a member of Class A is not allowed to take in marriage any woman he may choose from Class B, but only one from some specific sub-group of B. For example, a man of group n is restricted to a woman of group r. ”

“ There are, however, exceptions.787 Totemic clans are not exogamous in Central Australia, the Melanesian Banks Islands, among the Nandi of East Africa, and the Bakuana of South Africa. On the other hand, exogamy is found without totemism in the tribes just mentioned, among the Todas of Southern India, in Sumatra, among the African Masai and Ashanti, and in Southern Nigeria, and local exogamy among tribes (for example, the Kurnai of Southeast Australia, and the Californian Maidu and Shasta) in which totemic divisions are not perceptible. ”

“ This repugnance to marriage among people residing in close communities has been taken by Dr. Westermarck to be one of the causes which have led to exogamy.85 In this connection, the system of gang exogamy, prevalent among the gypsy Kanjars and Sânsiyas, with whom it is a rule that the bride must be selected from an encampment different from that of the bridegroom, is most significant. It is possible that here we are very close to exogamy in its most primitive form.86
25. In the same category are the numerous taboos of intercourse between a man and his wife and her relations. ”

“ The prevalence of exogamy in the primitive world is a fact too well known to need any explanation. With the growth of history, however, exogamy has lost its efficacy and, excepting the nearest blood-kins, there is usually no social bar restricting the field of marriage. But regarding the peoples of India the law of exogamy is a positive injunction even to-day. ”

“ Now all these factors—and others too perhaps—may very Such factors cannot fully explain exogamy well have had their influence in bringing about the practice of exogamy: in particular, it would seem that the difficulty of supporting a large family living together under really primitive [206] conditions would be very likely to have had the effect of driving the younger members of the family away from the immediate circle of their parents. Nevertheless there appears to be a pretty general agreement that none of these theories affords a complete and sufficient account of the origin of exogamy. ”

“ From the broader viewpoint of social evolution the problems of inbreeding or crossing of stocks merge into the discussion of the endogamous and exogamous types of society. Whatever may have been the origin of exogamy, the survival of the exogamous type in progressive societies may easily be explained on the ground of superior adaptability, variability and plasticity, which enables such societies to survive a change of environment while the more rigid structure of the endogamous clan brings about its extermination. ”

“ Morgan’s suggestion as to the origin of exogamy. Mr. M’Lennan did not live to publish a subtle theory of the origin of exogamy, which he had elaborated. In ‘Studies in Ancient History,’ he hazarded a conjecture based on female infanticide:—
‘We believe the restrictions on marriage to be connected with the practice in early times of female infanticide, which, rendering women scarce, led at once to polyandry within the tribe, and the capturing of women from without. ”

“ On the whole, wide prohibitions of marriage are archaic: the widest are savage; the narrowest are modern and civilised. Thus the Hindoo prohibition is old, barbarous, and wide. ‘The barbarous Aryan,’ says Sir Henry Maine, ‘is generally exogamous. He has a most extensive table of prohibited degrees.’ Thus exogamy seems to be a survival of barbarism. The question for us is, Can we call exogamy a survival from a period when (owing to scarcity of women and polyandry) clear ideas of kinship were impossible? ”

“ For an exogamous group would have a greater choice of women than an endogamous one, ... and in the competition for women the best would fall to the strongest and most warlike men. In this way the strengthened exogamous groups would in time exterminate the endogamous neighbours, or at least take away their best marriageable maidens. Exogamy would spread partly through imitation, partly through the extermination of endogamous groups. The fact that we cannot explain how it came about that the people varied in the aforesaid direction is not fatal to this hypothesis. ”

“ Incipient varieties are thus thrown off from the parent stock by means of peculiarities of sexual instinct which prompt what anthropologists call endogamy, and check exogamy or marriage without the tribe or caste. ”

“ No enquiry into the social relations of the Hindus can leave out of account the thorny subject of the origin of exogamy. By exogamy is generally understood the prohibition which exists against a man marrying within the group to which he belongs: to follow Mr. ”

“ For the same reason we may understand why the species of the same genus, or genera of the same family, resemble each other more nearly in their embryonic than in their more fully developed state, or how it is that in the eyes of most naturalists the structure of the embryo is even more important in classification than that of the adult, 'for the embryo is the animal in its less modified state, and in so far it reveals the structure of its progenitor. ”

“ In the fusion of the chromosomes of the male and female sexual cells, to which the hereditary transmission of the ancestral qualities to the new offspring is due, there are differences in the qualities of each, for the individuality of the parents is expressed in the germ cells, and the varying way in which these may fuse gives to the new cell qualities of its own in addition to qualities which come from each ancestor, and from remote ancestors through these. The qualities with which the new organism starts are those which it has received from its ancestors plus its individuality. ”

“ For all questions of evolution the presence of vestigial organs in the embryo is the important consideration, for they give an indication of near ancestry; the early formation of the embryo concerns a much more remote ancestral period, all vestigial organs of which may well have been lost and obscured by cœnogenetic changes. Let us, then, consider the two things—the vestigial organs and the early formation of the embryo—separately, and see how far my opponents are justified in their statement that my theory contravenes the principles of embryology. ”

“ Everyone would wish to explain to himself even in an imperfect manner, how it is possible for a character possessed by some remote ancestor suddenly to reappear in the offspring; how the effects of increased or decreased use of a limb can be transmitted to the child; how the male sexual element can act, not solely on the ovules, but occasionally on the mother form; how a hybrid can be produced by the union of the cellular tissue of two plants independently of the organs of generation ”

“ After this admission, however, nothing remains of the law of “recapitulation” except simple embryological homology comparable, in every sense, to adult homology, and adding nothing essentially new to the latter argument for evolution. It is, therefore, ridiculous for evolutionists to speak of branchial (gill) arches and clefts in man. The visceral or pharyngeal arches and grooves appearing in the human embryo are [Pg 279] unquestionably homologous with the genuine branchial arches and clefts in a fish embryo. ”

“ For in all higher animals, at least, offspring may possess some of the characteristics originally present in either of two lines of ancestry, and this commingling of such possessions is possible only through sexual reproduction. As has already been seen, in the pairing of chromosomes previous to reduction, the corresponding members of a pair always come together so that in the final segregation each gamete is sure to have one of each kind although whether a given chromosome of the haploid set is of maternal or paternal origin seems to be merely a matter of chance. ”

“ This mode of propagation has the further trait, that each fertilized germ usually gives rise to but one individual—the product of development is organized round one axis and not round several axes, Homogenesis in contrast with heterogenesis as exhibited in species which display distinct sexuality, has also the characteristic that each new individual begins as an egg detached from the maternal tissues, instead of being a portion of protoplasm continuous with them, and that its development proceeds independently. ”

“ But in some genera the larvæ become developed into hermaphrodites having the ordinary structure, or into what I have called complemental males; and in the latter the development has assuredly been retrograde; for the male is a mere sack, which lives for a short time and is destitute of mouth, stomach, and every other organ of importance, excepting those for reproduction.
We are so much accustomed to see a difference in structure between the embryo and the adult, that we are tempted to look at this difference as in some necessary manner contingent on growth. ”

“ How, then, can we explain these several facts in embryology,— namely, the very general, though not universal, difference in structure between the embryo and the adult;— the various parts in the same individual embryo, which ultimately become very unlike, and serve for diverse purposes, being at an early period of growth alike;— the common, but not invariable, resemblance between the embryos or larvæ of the most distinct species in the same class; the embryo often retaining, while within the egg or womb, structures which are of no service to it, either at that or at a later period of life ”

“ Parthenogenesis from a reduced egg gives rise to an organism having only the haploid number of chromosomes, as is the case with the drone or male bee, but unreduced eggs give rise to organisms having the diploid number of chromosomes. Parthenogenesis, as we shall see presently, can, in some cases, be induced by artificial means. When reproduction takes place from a zygote or diploid germ cell formed by the union of two gametes, we have what is known as bisexual reproduction or syngamy. ”

“ A hybrid embryo which partakes of the constitution of its father and mother is exposed to unnatural conditions, as long as it is nourished within the womb, or egg, or seed of the mother-form; and as we know that unnatural conditions often induce sterility, the reproductive organs of the hybrid might at this early age be permanently affected. ”

“ The increased development in the ovulum would not consist so much in the unusual form and thickening of the coat, a part of secondary importance, and whose nature is disputed, as in the state of the nucleus of the seed, respecting which there is no difference of opinion; and where the plurality of embryos, or at least the existence and regular arrangement of the cells in which they are formed, is the uniform structure in the family. ”

“ Both larvae and adults retain ancestral features, and both have been modified by an adaptation to their respective conditions of life which has ever been becoming more perfect.
The conclusion, then, has been reached, that whereas larvae frequently retain traces of ancestral stages of adult structure, embryos will rarely do so; and we are confronted again with the question, How are we to account for the presence in the embryo of numerous functionless organs which cannot be explained otherwise than as having been inherited from a previous condition in which they were functional? ”

“ We know that the germ-plasm of each individual is not a simple substance, but possesses a very complex composition, for it consists of a number of ancestral germ-plasms represented in very different proportions. Now, although we cannot learn anything directly about the processes of growth of the germ-plasm, and its resulting ontogenetic stages, yet we do know, chiefly from observations upon man, that the characters of ancestors appear in the offspring in very different combinations and in very different degrees of strength. ”

“ Thus, as it seems to me, the leading facts in embryology, which are second to none in importance, are explained on the principle of variations in the many descendants from some one ancient progenitor, having appeared at a not very early period of life, and having been inherited at a corresponding period. Embryology rises greatly in interest, when we look at the embryo as a picture, more or less obscured, of the progenitor, either in its adult or larval state, of all the members of the same great class. ”

“ The single-chromosome generation, which I will call the HAPLOID, must have been the primitive generation in all organisms; it might also persist as the only generation. Every sexual differentiation in organisms, which occurred in the course of phylogenetic development, was followed by fertilisation and therefore by the creation of a diploid or double-chromosome product. ”

“ The sterility of first crosses between pure species, which have their reproductive systems perfect, seems to depend on several circumstances; in some cases largely on the early death of the embryo. The sterility of hybrids which have their reproductive systems imperfect, and which have had this system and their whole organization disturbed by being compounded of two distinct species, seems closely allied to that sterility which so frequently affects pure species when their natural conditions of life have been disturbed. ”