(Concluded)
It has been asserted that, if there be really an innate horror of incest, it ought to show itself intuitively when persons are ignorant of any relationship. But ancient writers state that, in Rome, incestuous unions often resulted from the exposure of infants who were reared by slave-dealers. Not long ago Selim Pasha unwittingly married his sister, who, like himself, had been a Circassian slave. The story told in the ‘Heptameron’ of a double incest was probably true, and became widely spread; and so on. Man has thus no horror of marriage with even the nearest kindred if he is unaware of their consanguinity; consequently, Mr. Huth concludes, there is no innate feeling against incest.1903
Of course I agree with Mr. Huth in thinking that there is no innate aversion to marriage with near relations. What I maintain is, that there is an innate aversion to sexual intercourse between persons living very closely together from early youth, and that, as such persons are in most cases related, this feeling displays itself chiefly as a horror of intercourse between near kin.
The existence of an innate aversion of this kind has been taken by various writers as a psychological fact proved by common experience;1904 and it seems impossible otherwise to explain the feeling which makes the relationships between parents and children, and brothers and sisters, so free from all sexual excitement. But the chief evidence is afforded by an abundance of ethnographical facts which prove that it is not, in the first place, by the degrees of consanguinity, but by the close living together that prohibitory laws against intermarriage are determined.
Egede asserts that, among the Greenlanders, it would be reckoned uncouth and blamable, if a lad and a girl who had served and been educated in one family, desired to be married to one another;1905 and, according to Dr. Nansen, it is preferred that the contracting parties should belong to different settlements.1906 Colonel Macpherson states that, among the Kandhs, marriage cannot take place even with strangers who have been long adopted into, or domesticated with, a tribe.1907 And Mr. Cousins writes to me that the Cis-Natalian Kafirs dislike marriage between persons who live very closely together, whether related or not. In the Northern New Hebrides, a girl betrothed in childhood is sometimes taken to her future father-in-law’s house and brought up there. Dr. Codrington says that “the boy often thinks she is his sister, and is much ashamed when he comes to know the relation in which he stands.”1908
Many peoples have a rule of exogamy that does not depend on kinship at all. Piedrahita relates of the Panches of Bogota that the men and women of one town did not intermarry, as they held themselves to be brothers and sisters, and the impediment of kinship was sacred to them; but such was their ignorance that, if a sister were born in a different town from her brother, he was not prevented from marrying her.1909 The Yaméos, on the river Amazons, will not suffer an intermarriage between members of the same community, “as being friends in blood, though no real affinity between them can be proved.”1910 The Uaupés, according to Mr. Wallace, “do not often marry with relations, or even neighbours, preferring those from a distance, or even from other tribes.”1911 The Australian tribe, as Mr. Howitt points out, is organized in two ways. On the one hand, it is divided socially into phratries and clans; and, on the other hand, it is divided geographically into hordes. The two organizations are co-existent, but the divisions of the one do not correspond with those of the other. For while all the people who belong to any given local group are found in one locality alone, those who belong to any given social group are to be found distributed among many, if not among all, of the local groups. Now, in many tribes, local proximity by birth is quite an insuperable obstacle to marriage, a man being absolutely forbidden to marry, or have sexual intercourse with, a woman of the same horde or sub-horde. “However eligible she may be in other respects,” says Mr. Howitt, “the fact that both parties belong to the same locality is held by certain tribes, the Kurnai, for example, to make them ‘too near each other.’” It is chiefly in tribes where the clan-system has been weakened, or has become almost extinct, that the local organization has assumed such overwhelming preponderance, but even in some of the tribes which have a vigorous clan-system, local restraints upon marriage are strictly enforced.1912 In Sumatra, according to Mr. Forbes, the country was originally divided into native districts called “margas,” each marga, as a rule, having its several villages. Each of these village communities is a collection of families, either related or not to each other by the ties of blood;1913 and we know that, at least among certain tribes, marriage between members of the same village or village cluster, and in some districts even between those of the same marga, is prohibited.1914 The Kotars of the Neilgherries,1915 Galela,1916 Fijians,1917 Zulus,1918 Wakamba,1919 and Kamchadales1920 avoid, as a rule, marriage with members of the same village. So also do the Nogai, who consider it most honest for a man to marry a woman whom he has never seen before.1921 In various of the smaller islands belonging to the Indian Archipelago, according to Riedel, women prefer marriage with strangers.1922 The Assamese have a national festival named the “Baisakh Bihu,” which is as gay as a carnival, the women, and especially the maidens, enjoying unusual liberty as long as it lasts. “For many days before the actual festival,” says Colonel Dalton, “the young people in the villages may be seen moving about in groups gaily dressed or forming circles, in the midst of which the prettiest girls dance with their long hair loose on their shoulders.” But on these occasions the girls “do not like to dance before the men of their own village.”1923 Professor Kovalevsky observes that, in some parts of Russia, the bride is always taken from another village than the bridegroom’s; and, even in provinces in which no similar custom is known to exist, “the bridegroom is constantly spoken of as a foreigner (‘choujoy,’ ‘choujaninin’), and his friends and attendants are represented as coming with him from a distant country, in order to take away the future spouse.”1924 Sir Richard Burton says, “As a general rule Somali women prefer amourettes with strangers, following the well-known Arab proverb, ‘The new comer filleth the eye.’”1925
We have seen how variously defined the prohibited degrees are in the laws of nations. Facts show that the extent to which relatives are not allowed to intermarry is nearly connected with their close living together. Generally speaking, the prohibited degrees are extended much farther among savage and barbarous peoples than in civilized societies. As a rule, the former, if they have not remained in the most primitive social condition of man, live, not in separate families, but in large households or communities, all the members of which dwell in very close contact with each other.
The communism in the family life of the exogamous Indians of North America has been exhaustively illustrated by Mr. Morgan in his work on ‘Houses and House-Life of the American Aborigines.’ “The household of the Mandans,” he says, “consisting of from twenty to forty persons, the households of the Columbian tribes of about the same number, the Soshonee household of seven families, the households of the Sauks, of the Iroquois, and of the Creeks, each composed of several families, are fair types of the households of the Northern Indians at the epoch of their discovery. The fact is also established that these tribes constructed, as a rule, large joint tenement houses, each of which was occupied by a large household composed of several families, among whom provisions were in common, and who practised communism in living in the household.”1926 Among the Iroquois, each household was made up on the principle of kinship through females, so that the married women, usually sisters, own or collateral, being of the same gens or clan, together with their children made a family circle, within which, as we have seen, intermarriage was entirely prohibited.1927 The Senel in California live sometimes from twenty to thirty together in the same immense dome-shaped or oblong lodge of willow-poles, including all who are blood relations.1928 According to Egede, the Greenlanders, who prohibit marriage between cousins, continue after marriage to live in their parents’ house together with other kindred; and what they get they all enjoy in common.1929 The Chippewas, who consider cousins german in the same light as brothers and sisters, but do not recognize relationship beyond this degree, are divided into small bands consisting of but few families each.1930 Among the exogamous Uaupés, the houses are the abode of numerous families, and sometimes of a whole horde.1931 Among the Yahgans, who regard marriage between first and second cousins as incestuous, “occasionally as many as five families are to be found living in a wigwam, but generally two families.”1932
The Australian aborigines live mostly in small hordes, often consisting of from thirty to fifty men, women, and children. Such a horde, according to Mr. Brough Smyth, “is in fact but an enlargement of a family circle, and none within it can intermarry.”1933 Among the Efatese, in whose clan-system the prohibition of incest is a fundamental law, each clan is regarded as one family. “A child of a,” says Mr. Macdonald, “calls her own mother mother, and all her mother’s tribe (clan) sisters mother; and calls by the name of father not only her own father but all his tribe (clan) brothers; and they all call the child their child.”1934 The Malays, according to Professor Wilken, live, as a rule, in large houses containing a great number of differently related persons.1935 “In Nanusa,” Dr. Hickson remarks, “I understood that marriage was not permitted between members of the same household. The enormous households of the Nanusa archipelago are probably the remnants of a much more complete system of intra-tribal clanships, which has become almost obliterated in the more highly developed races of Sangir and Siauw.”1936 Among the Nairs, a household, the members of which are strictly prohibited from sexual relation with each other, includes, as a rule, many allied men, women, and children, who not only live together in large common houses, but possess everything in common.1937 Among the Kafirs, the dimensions of a kraal are determined by the number of a man’s family and dependants, the family consisting of the father together with his children, including married sons.1938
The South Slavonians live in house-communities, each consisting of a body of from fifteen to sixty members or even more, who are blood-relations to the second or third degree, of course only on the male side.1939 These related families associate in a common dwelling or group of dwellings, governed by a common chief. “At the present moment,” Sir Henry Maine remarks, “the common residence of so many persons of both sexes in the same household may be said to be only possible through their belief that any union of kinsmen and kinswomen would be incestuous. The South Slavonian table of prohibited degrees is extremely wide.”1940 Again, Professor Kohler points out the connection between the extensive prohibitions of the Hindus and their large households.1941 In Wales there existed, as a national institution, a joint-family called “trev,” consisting of four generations. Marriage, says Mr. Lewis, was to be “outside the trev, or kindred who lived together within one enclosure.”1942
Montesquieu, indeed, observed long ago that marriage between cousins was prohibited by peoples among whom brothers and their children used to live in the same house. “Chez ces peuples,” he says, “le mariage entre cousins germains doit être regardé comme contraire à la nature; chez les autres, non.” According to him, this prohibition has the same origin as the aversion to sexual relations between brothers and sisters, i.e., “les pères et les mères ayent voulu conserver les mœurs de leurs enfans et leurs maisons pures.”1943 Holding a similar opinion, Dr. Bertillon maintains that, properly speaking, it was not consanguinity, but the purity of home, that the ancient legislators were thinking of when they forbade close intermarriage.1944 It is scarcely necessary to say how far I am from thinking that these prohibitions are, in the first place, due to the providence of parents or legislators.
On the other hand, where the families live more separately such extensive prohibitions to close intermarrying do not generally exist. Among the Isánna Indians of Brazil, who prefer marriage with relations, cousins with cousins, uncles with nieces, and nephews with aunts, each family has a separate house.1945 The endogamous Maoris, who frequently marry near relations, have their villages generally scattered over a large plot of ground, the personal rights of possession being held most sacred.1946 “There is no national bond of union amongst them,” says Mr. Yate; “each one is jealous of the authority and power of his neighbour; the hand of each individual is against every man, and every man’s hand against him.”1947 Among the Todas, who live in strict endogamy, families reside in permanent villages having each a certain tract of grazing ground around it, and containing from two to three huts. Most of these huts consist of only one room or cabin, and each room holds one entire subdivision of a family.1948 The Bushmans, among whom no degree of consanguinity prevents a matrimonial connection, except between brothers and sisters, parents and children,1949 live a solitary life in small family huts, not high enough to admit even of a Bushman standing upright within it.1950 As regards the Wanyoro, whose table of prohibited degrees is unusually small, Emin Pasha states, “Brother, sister, brother-in-law, and son-in-law, are the recognized grades of relationship. I have never noticed any intimate connection between more distant relations.”1951
The Sinhalese, who frequently marry their cousins on the paternal side, have from time immemorial lived either in very small villages, consisting of a few houses, or in detached habitations, separated from each other. Each dwelling is a little establishment in itself, and each little village, so far as its wants are concerned, may be considered independent. “They seldom visit each other, except it be to beg or borrow something. Even near relations manifest no affection to each other in their visits, but sit with the gravity of strangers.”1952
It is easy to explain, says Ewald, why, among the Hebrews, marriage between brothers and sisters in the widest sense was forbidden, while that between cousins was permitted:—“The latter did not form one united household, and the more each house stood strictly by itself in the ancient fashion, the wider seemed the separation between cousins.”1953 Tacitus states that the ancient Germans, whose prohibitions against incest seem to have included only the nearest relations, lived in scattered families at some distance from each other.1954 And a comparison between the forbidden degrees of the Greeks and Romans clearly shows where we have to seek the real cause of the prohibitions. Among the former, even very close relationship was no hindrance to intermarriage, whereas, among the latter, it was not allowed between rather distantly related persons. This difference, as Rossbach justly points out, was due to the fact that the family feeling of the Greeks was much weaker than that of the Romans, among whom, in early times, a son used to remain in his father’s house even after marriage, so that cousins on the father’s side were brought up as brothers and sisters. Later on, the several families separated from the common household, and the prohibited degrees were considerably retrenched.1955
The reader may perhaps be disposed to reproach me for selecting only such instances as are in favour of my theory; but statistical data will show that such an imputation would be groundless. In speaking of the “classificatory system of relationship,” I pointed out that this system springs, to a great extent, from the close living together of considerable numbers of kinsfolk. Now it is most interesting to note that Dr. Tylor, by his method of adhesions, has found the two institutions, exogamy and classificatory relationship, to be in fact two sides of one institution. “In reckoning,” he says, “from the present schedules the number of peoples who use relationship names more or less corresponding to the classificatory systems here considered, they are found to be fifty-three, and the estimated number of these which might coincide accidentally with exogamy, were there no close connection between them, would be about twelve. But in fact the number of peoples who have both exogamy and classification is thirty-three, this strong coincidence being the measure of the close casual connection subsisting between the two institutions. The adherence is even stronger as to cross-cousin marriage (i.e., that the children of two brothers may not marry, nor the children of two sisters, though the child of the brother may marry the child of the sister), of which twenty-one cases appear in the schedules, no less than fifteen of the peoples practising it being also known as exogamous.”1956 Among the Reddies, a father’s elder brother and a mother’s elder sister are called, respectively, “great-father” and “great mother,” and a father’s younger brother and a mother’s younger sister, respectively, “lesser-father” and “lesser mother”; whereas the father’s sisters and the mother’s brothers are denoted by quite different terms. Mr. Kearns remarks that they consider the difference as well as the distance of relationship between these two groups of relations to be so great that they think it unlawful and incestuous to marry the daughter of a father’s brother or of a mother’s sister, she being equal to a sister, whilst it is perfectly legal to marry the daughter of a father’s sister or of a mother’s brother.1957
We have seen that the prohibitions against incest are very often more or less one-sided, applying more extensively either to the relations on the father’s side or to those on the mother’s, according as descent is reckoned through men or women. We have also seen that the line of descent is intimately connected with local relationships; and we may now fairly infer that the same local relationships exercise a considerable influence on the table of prohibited degrees. Among the Rejangs of Sumatra, says Marsden, a marriage must not take place between relations within the third degree; “but there are exceptions for the descendants of females who, passing into other families, become as strangers.”1958 A Chinese woman, on marriage, alienates herself from her own family to be incorporated into that of her husband; hence, as Mr. Medhurst observes, children of brothers and sisters may marry at pleasure, while those of brothers cannot be united on pain of death.1959
In a large number of cases, prohibitions of intermarriage are only indirectly influenced by the close living together. Aversion to the intermarriage of persons who live in intimate connection with each other has provoked prohibitions of the intermarriage of relations; and, as kinship is traced by means of a system of names, the name comes to be considered identical with relationship. This system, as Dr. Tylor remarks,1960 is necessarily one-sided. Though it will keep up the record of descent either on the male or female side, it cannot do both at once. The other line, not having been kept up by such means of record, even where it is recognized as a line of relationship, is more or less neglected, and is soon forgotten; hence the prohibited degrees often extend very far on the one side, but not on the other. We have seen many instances of a common surname being a bar to intermarriage. This is especially the case with peoples among whom the clannish feeling is highly developed. Thus even the commonest Chinese are often able to trace their descent through lines of ancestry more remote than any that England’s most ancient families can claim.1961 And, among the Ossetes, a man is bound to take blood-revenge for a cousin a hundred times removed who bears his name, whereas relationship on the mother’s side is not recognized.1962
Generally speaking, the feeling that two persons are intimately connected in some way or other may, through an association of ideas, give rise to the notion that marriage or intercourse between them is incestuous. Hence the prohibitions of marriage between relations by alliance and by adoption. Hence, too, the prohibitions on the ground of what is called “spiritual relationship.” The Emperor Justinian passed a law forbidding any man to marry a woman for whom he had stood as godfather in baptism, the tie of the godfather and godchild being so analogous to that of the father and child as to make such a marriage appear improper.1963 In the Roman Church sponsorship creates a bar to the marriage even of co-sponsors, and the restriction can be removed only by a dispensation.1964 In Eastern Europe, the groomsman at a wedding comes under a set of rules which forbids intermarriage with the family of the bride to exactly the same extent as if he were naturally the brother of the bridegroom.1965 A similar cognatio spiritualis, according to the old law-books of India, occurs between a pupil and his “guru,” that is, the teacher who instructs him in the Veda. The pupil lived in his guru’s house for several years, and regarded him almost as a father.1966 Hence adultery with a guru’s wife was considered a mortal sin.1967
But how, then, are we to explain the exceptions, apparent or real, to the rule that close living together inspires an aversion to intermarriage? How are we to explain the fact that, besides tribes that are exogamous, there are others that are endogamous, and that, besides peoples with very extensive laws against intermarriage, there are others among whom unions take place between very near relations, such as brothers and sisters, and even parents and children.
In the next chapter we shall examine the psychological principle which underlies the endogamous marriage. For the present it is sufficient to say that endogamy never, except in cases of extreme isolation, seems to occur among peoples living in very small communities with close connections between their members. Concerning the Australians, Mr. Curr expressly states that those tribes which are endogamous are, as a rule, stronger in numbers than those in which exogamous marriage obtains.1968
The marriage of brother and sister means, as we have seen, in most cases, marriage between a half-brother and a half-sister, having the same father but different mothers. Such marriages are not necessarily contrary to the principle here laid down. Polygyny breaks up the one family into as many sub-families as there are wives who have children, and it is not possible for the father of these sub-families to be a member of each of them in the same sense as the father is a member of the monogamous family. Nor are the children of the different mothers brought into such close contact as the children of one mother, every wife with her own family forming a little separate group, and generally living in a separate hut.1969 On the contrary, hatred and rivalry are of no rare occurrence among the members of the various sub-families. In the Pelew Islands, according to Herr Kubary, it very seldom happens that the several wives of the same man even see each other.1970 After speaking of the marriage of half-brother and half-sister allowed among the ancient Arabs, Professor Robertson Smith remarks, “Whatever is the origin of bars to marriage, they certainly are early associated with the feeling that it is indecent for housemates to intermarry.”1971
Most of the recorded instances of intermarriage of brother and sister refer to royal families, to the exclusion of others; and there is no difficulty in accounting for incestuous unions of this sort. Among lower races, as well as in Europe, it is considered improper for royal persons to contract marriage with persons of less exalted birth. But whilst European princes may go to some friendly Court for their consorts, a similar course is not open to African or Asiatic potentates.
Incestuous unions may also take place on account of necessity, as among the Wa-taïta, or on account of extreme isolation, as among the Karens of the Tenasserim Provinces,1972 several of the small tribes of Brazil, and especially the Veddahs of Ceylon. Among the wild Veddahs, the different families are separated from each other by great distances, and it is only accidentally or occasionally that any others besides the members of one family are brought together.1973 The reason for the practice of marrying a sister, says Professor Virchow, “was probably the same everywhere, in the royal families as with the naked Veddahs, the lack of suitable women or of women altogether.”1974
Certain instances of incestuous connection are evidently the results of vitiated instincts, the origin of which we are not able to trace. It is a remarkable fact that several of the peoples among whom incestuous intercourse is said to be practised are, at the same time, expressly stated to indulge in bestiality or other unnatural vices.1975 This shows that their sexual feelings are altogether in a perverted state.
Much stress has been laid by anthropologists on the few instances of peoples who habitually or occasionally contract unions which we should consider criminal. They have been taken for surviving types of the primitive condition of man, proving that “sentiments such as those which among ourselves restrain the sexual instincts are not innate.”1976 But it is obvious that they prove nothing of the kind. Students of early history have often paid too much regard to exceptions, and too little to rules, overlooking the fact that there is no rule which has no exceptions.
It may be objected that no feeling of incest exists among the lower animals.1977 According to Mr. Huth, incest “is constantly practised by animals, and habitually by those which are polygamous.”1978 But, as we have previously seen, among species that live in families, the young, without exception, leave the family as soon as they are able to shift for themselves; and Mr. Huth has adduced not the slightest evidence for his statement that “polygamy among animals means the closest incest.”1979
The hypothesis here advocated can, I think, account for all the facts given in the last chapter. It explains how the horror of incest may be independent of experience as well as of education; why the horror of incest refers not only to relations by blood, but very frequently to persons not at all so related; why the prohibitions of consanguineous marriages vary so considerably with regard to the prohibited degrees, applying, however, almost universally to persons who live in the closest contact with each other; and why these prohibitions are so commonly extended much farther on the one side, the paternal or the maternal, than on the other. The question now arises:—How has this instinctive aversion to marriage between persons living closely together originated?
We have seen that a certain degree of similarity as regards the reproductive system of two individuals is required to make their union fertile and the progeny resulting from this union fully capable of propagation. It might, then, be supposed that the highest degree of similarity must be the most beneficial; but in all probability this is not the case. It seems to be necessary not only that the sexual elements which unite shall be somewhat like, but that they shall be in some way different. The similarity must not be too great.
Mr. Darwin, by his careful studies on the effects of cross- and self-fertilization in the vegetable kingdom, contributed more largely than any one else to the discovery of this law. He watched, from germination to maturity, more than a thousand individual plants, produced by crossing and self-fertilization, belonging to fifty-seven species, fifty-two genera, and thirty large families, and including natives of the most various countries.1980 The result established by this research was, that cross-fertilization is generally beneficial, and self-fertilization injurious; which is shown by the difference in height, weight, constitutional vigour, and fertility of the offspring from crossed and self-fertilized flowers, and in the number of seeds produced by the parent-plants.1981 Hence, whenever plants which are the offspring of self-fertilization are opposed in the struggle for existence to the offspring of cross-fertilization, the latter have the advantage. And this follows, according to Mr. Darwin, from individuals of two distinct kinds having been subjected during previous generations to different conditions, or to their having varied from some unknown cause in a manner commonly called spontaneous, because of that innate tendency to vary and to advance in organization which exists in all beings; so that in either case their sexual elements have been in some degree differentiated.1982
As for the animal kingdom, Mr. Darwin remarks that almost all who have bred many kinds of animals, and have written on the subject, have expressed the strongest conviction on the evil effects of close interbreeding.1983 “Indeed,” says Sir J. Sebright, “I have no doubt but that, by this practice being continued, animals would, in course of time, degenerate to such a degree as to become incapable of breeding at all.... I have tried many experiments by breeding in-and-in upon dogs, fowls, and pigeons; the dogs became, from strong spaniels, weak and diminutive lap-dogs, the fowls became long in the legs, small in the body, and bad breeders.”1984 Mr. Huth, on the other hand, denies that breeding in-and-in, however close, has proved to be in itself hurtful, and quotes the evidence of numerous breeders whose choicest stocks have always been so bred. But in these cases, as Mr. Wallace remarks, “there has been rigid selection by which the weak or the infertile have been eliminated, and with such selection there is no doubt that the ill effects of close interbreeding can be prevented for a long time; but this by no means proves that no ill effects are produced.”1985 The consensus of opinion on this point among eminent breeders is indeed overwhelming, and cannot be reasoned away. According to Crampe’s experiment with the brown rat (Mus decumanus), thirty-nine animals out of 153 born by related parents, i.e., 25·5 per cent., died soon after birth, whereas of 299 animals of parents not related this was the case with twenty-eight only, i.e., 8·4 per cent. The animals of incestuous broods were much smaller and lighter than others, and their fecundity was diminished.1986 Mr. Huth himself observed, when breeding rabbits in-and-in, that “after the fourth generation there was a diminution of fecundity analogous to the disgust that the stomach would feel at the same diet long continued,” though he found no evil effect in any other way. On the contrary, the in-and-in bred offspring were somewhat heavier than the non-related parent animals.1987 Professor Preyer has made a similar observation with regard to guinea-pigs: breeding in-and-in produced a considerable loss of fertility, but was accompanied with an increase of weight.1988 This seems to indicate that the effects of close interbreeding are not always the same.
There are certainly breeders who prefer connecting together the animals nearest allied in blood to one another. But, as Dr. Mitchell observes, “when breeding in-and-in has been practised with so-called good results, the issue is nothing but the development of a saleable defect, which, from the animal’s point of view, must be regarded as wholly unnatural and artificial, and not calculated to promote its well-being or natural usefulness.”1989
Many writers suppose that all the evils from close interbreeding depend upon the combination and consequent increase of morbid tendencies common to both parents, the state of whose health decides whether union would be favourable or not to the offspring. “If the parents are perfectly healthy,” says M. Pouchet, “and exempt from all commencing degeneracy, they can only give birth to children at least as healthy as themselves.... But if the same degeneracy has already tainted both the parents, the offspring will show it in a greater degree, and will tend towards entire disappearance.”1990 The same opinion is held by Sir John Sebright. But being, as an experienced breeder, well aware of the injurious results which almost always follow from interbreeding animals too closely, he adds that, according to his belief, there never did exist an animal without some defect, in constitution, in form, or in some other essential quality, or that at least a tendency to the same imperfection generally prevails in the same family.1991
Mr. Darwin, however, has shown it to be highly probable that, though the injury has often partly resulted from the combination of morbid tendencies, the general cause is different. Considering the number of self-fertilized plants that were tried, he thinks it is nothing less than absurd to suppose that in all these cases the mother-plants, though not appearing in any way diseased, were weak or unhealthy in so peculiar a manner that their self-fertilized seedlings, many hundreds in number, were rendered inferior in height, weight, constitutional vigour, and fertility to their crossed offspring.1992 Moreover, self-fertilization and close interbreeding induce sterility, and this indicates something quite different from the augmentation of morbid tendencies common to both parents.1993 Hence it seems to be almost beyond doubt that, just as the sterility of distinct species when first crossed, and of their hybrid offspring, depends on their sexual elements having been differentiated in too great a degree, the evils of close interbreeding, or self-fertilization in plants, result chiefly from their sexual elements not having been sufficiently differentiated. But we do not know why a certain amount of differentiation is necessary or favourable for the fertilization or union of two organisms, any more than for the chemical affinity or union of two substances.1994 It must, however, be observed that no case of complete sterility is met with in self-fertilized seedlings, as is so common with hybrids,1995 and that interbreeding even of the nearest relations may sometimes, under very favourable circumstances, be continued through several generations without any evil results making their appearance.
It is impossible to believe that a law which holds good for the rest of the animal kingdom, as well as for plants, does not apply to man also. But it is difficult to adduce direct evidence for the evil effects of consanguineous marriages. We cannot expect very conspicuous results from other alliances than those between the nearest relations—between brothers and sisters, parents and children. And the injurious results even of such unions would not necessarily appear at once. Sir J. Sebright remarks that there may be families of domestic animals which go through several generations without sustaining much injury from having been bred in-and-in,1996 and the offspring of self-fertilized plants do not always show any loss of vigour in the first generations. Man cannot, in this respect, be subjected to experiments like those tried in the case of other animals, and habitual intermarriage of the very nearest relations is, as we have seen, exceedingly rare. Mr. Adam argues that there is no proof of the physical deterioration of those divisions of mankind amongst whom incestuous unions are known more or less to have prevailed—as the Egyptians and Persians.1997 But among these nations marriage certainly did not always take place between closely related persons; and breeders of domestic animals inform us that the mixing-in even of a drop of unrelated blood is sufficient almost to neutralize the injurious effects of long continued close interbreeding. Again, Mr. Huth asserts that, though the Ptolemies habitually married their sisters, nieces, and cousins, they were neither sterile nor particularly short-lived.1998 Mr. Galton, on the contrary, sees in Ptolemaic experience a proof that close intermarriage is followed by sterility.1999 In ten marriages between brothers and sisters, uncles and nieces, or between first-cousins, the average number of children was not quite two, and three of the unions were entirely sterile.2000
The Veddahs of Ceylon are probably the most in-and-in bred people that ever existed. Among them, the practice of a man marrying his younger sister did not occur only occasionally; according to Mr. Bailey, it was the proper marriage. Among the Bintenne Veddahs, it may be said to have been, for perhaps two generations or so, extinct, whilst among those of Nilgala, it is at most only disappearing. Mr. Bailey believes that this practice is quite sufficient to account for the short stature as well as the weak and vacant expression of this people. He did not find many traces of insanity, idiocy, and epilepsy—maladies which such marriages, according to a common belief, might be supposed to produce. “But in other respects,” he says, “the injurious effects of this custom would seem to be plainly discernible. The race is rapidly becoming extinct; large families are all but unknown, and longevity is very rare. I have been at some pains to obtain reliable data to elucidate these points. Out of seventy-two Veddahs in Nilgala, fifty were adults, and twenty-two children. In one small sept, or family, there were nine adults and one child; in another, one child and eight adults; and so on. In Bintenne, out of three hundred and eight Veddahs, a hundred and seventy-five were adults and a hundred and thirty-three children. Here the disproportion is not so marked; but in one of the smaller tribes, more isolated than the rest, there were twenty adults, and but four children. The paucity of children, I think, must be ascribed to the degeneracy produced by such close intermarriages, for I have never heard a suspicion of infanticide existing among them. Out of fifty adults in Nilgala, only one appeared to have numbered seventy years, and but eight to have exceeded fifty. In Bintenne, of a hundred and seventy-five adults, two only seemed to have reached their seventieth, and but fourteen to have exceeded their fiftieth year. Such statistics seem to show the practical results of such connections. The Nilgala Veddahs, who still maintain an almost total isolation from other people, are rapidly disappearing. The Veddahs of Bintenne, who have abandoned the pernicious custom which I have described, and still intermarry among themselves, are becoming extinct, though more gradually.”2001
With the exception of this case, the closest kind of intermarriage which we have opportunities of studying is that between first cousins. Unfortunately, the observations hitherto made on the subject are far from decisive. Several writers, as M. Périer, Dr. Voisin, and Mr. Huth, believe that there are no injurious results at all from those marriages, unless the parents are afflicted with the same hereditary morbid tendencies,2002 whilst others, as M. Devay and M. Boudin, express the most alarming opinions as to the bad effects of consanguineous marriages. Such alliances are supposed to bring evils of many different kinds upon a population, as sterility, idiocy, epilepsy, insanity, deaf-muteism, congenital malformations in the offspring, cretinism, albinoism,2003 &c. But how little the statements of the various writers agree with each other appears, for instance, from the fact that M. Boudin found the proportion of deaf-mutes born in consanguineous marriages, in the Imperial Institution of Deaf-Mutes at Paris, to be 28·35 per cent., whereas, according to Dr. Mitchell, it amounts to 5·17 per cent. in Scotch and English institutions.2004
As it is impossible to dwell here upon the investigations of the several writers, of which Mr. Huth has given so complete an account, I shall confine myself to a statement of the general results attained by those investigators who have founded their inquiries on a more trustworthy statistical basis.
Adopting a method different from that of his predecessors, Professor G. H. Darwin has endeavoured first to discover the proportion of consanguineous marriages in the whole population, and then to find out whether the offspring of those marriages exhibit a greater percentage of individuals, defective in one way or another, than the offspring of non-consanguineous marriages. His investigations tend decidedly to invalidate the exaggerated conclusions of many previous writers, but he thinks that “there are nevertheless grounds for asserting that various maladies take an easy hold of the offspring of consanguineous marriages.”2005 He did not find evidence that the marriage of first cousins had any effect in the production of infertility, deaf-muteism, insanity, or idiocy, but he observed a slightly lowered vitality amongst the offspring of first cousins, and a somewhat higher death-rate than amongst the families of non-consanguineous marriages.2006 Moreover, the numbers of boating men belonging to the twenty boats at Oxford and thirty at Cambridge, in the first and second division, and those of selected athletes from some schools in England, justified, to some extent, the belief “that offspring of first cousins are deficient physically, whilst at the same time they negative the views of alarmist writers on the subject.”2007 It is curious that, in spite of such unambiguous statements, Mr. Darwin’s paper has generally been quoted as an evidence of the perfect harmlessness of first cousin marriages.
M. Stieda has found that, in the departments of France, the number of bodily or mentally infirm people increases almost constantly in proportion to the number of consanguineous marriages, as will be seen from the following table:—