There are several isolated communities—in Java, Peru, Great Britain, France, Scandinavia, &c.—which intermarry solely among themselves without any evil effects being discernible. An often-quoted case is the community of Batz (3,300 persons), situated near Croisic on a peninsula. The inhabitants of this community have been in the habit of closely intermarrying among themselves from time immemorial. Nevertheless, they are almost all very well in health without any hereditary affection. But Dr. Voisin observes, “Les conditions climatériques de la commune de Batz, son voisinage de la mer, l’hygiène et les habitudes de ses habitants, semblent s’accorder pour empêcher la dégénérescence de l’espèce et paraissent expliquer l’innocuité des mariages entre consanguins qui s’y pratiquent depuis plusieurs siècles.”[2015] In other isolated communities the population is not so numerous, and the sanitary conditions are not perhaps so favourable: but in any case we may say that this local endogamy is generally something quite different from marriage with near relations. Dr. Mitchell found that, in almost all the isolated communities along the coasts of Scotland, which had been given as instances of close interbreeding, such marriages were comparatively rare. According to Dr. Mygge, the like is true of the population of Lyø and Strynø in Denmark.[2016] And Dr. Andrew Wood states, of the fisher-folk of Newhaven, that, though they keep themselves much segregated, they are very careful regarding intermarriage, and look upon the union of relatives as an infringement of the laws of morality.[2017]
Moreover, even if it could be proved that, in particular cases, close intermarrying, though continued for a long time, has been followed by no bad consequences, this would be no evidence that consanguineous marriages are as a rule innocuous. In some parishes of Denmark Dr. Mygge found no evil effects of such marriages, whilst in others they were very conspicuous.[2018] And from the investigations of Mr. Darwin it appears that, notwithstanding the injury which most plants suffer from self-fertilization, a few have almost certainly been propagated in a state of nature for thousands of generations without having been once intercrossed. It is impossible to understand, he says, why some individuals even of the same species are sterile, whilst others are quite fertile, with their own pollen.[2019]
There is evidence that the bad consequences of self-fertilization and close interbreeding may almost fail to appear under favourable conditions of life. In-and-in bred plants, when allowed enough space and good soil, frequently show little or no deterioration: whereas, when placed in competition with another plant, they often perish or are much stunted.[2020] Crampe’s experiments with brown rats proved that the breeding in-and-in was much less injurious, if the offspring of the related parents were well fed and taken care of, than if it was otherwise.[2021] And this is in striking accordance with Dr. Mitchell’s observations as to consanguineous marriages in Scotland. The results there appear to be least grave, and are frequently almost nil, if the parents and children live in tolerable comfort, without anxiety or much thought for the morrow, and easily earning enough to procure good food and clothing—in short, when they work, but do not struggle for existence. On the other hand, when they are “poor, pinched for food, scrimp of clothing, badly housed, and exposed to misery; when they have to toil and struggle for the bare necessaries of life—never having enough for to-day and being always fearful of to-morrow,”—the evil may become very marked.[2022]
If this is the case, we must expect to find that consanguineous marriages are much more injurious in savage regions, where the struggle for existence is often very severe, than they have proved to be in civilized society, especially as it is among the well-off classes that such marriages occur most frequently.[2023] In England, according to Mr. G. H. Darwin, cousin-marriages among the aristocracy are probably 4½ per cent.; among the middle and upper middle class, or among the landed gentry, 3½ per cent.; but in London, comprising all classes, they are probably only 1½ per cent.[2024] He thinks that the slightness of the evils which he found to result from first-cousin marriages perhaps depends upon the fact that a large majority of Englishmen live under what are on the whole very favourable circumstances.[2025] We must also, however, remember that there has been a great mixture of races in Europe, and that this necessarily makes marriage of kinsfolk less injurious, so far as the evil results of such unions depend upon too great a likeness between the sexual elements.
The conclusion that closely related marriages produce more destructive effects among savage than civilized peoples, derives perhaps, some additional probability from certain ethnological facts. These facts may, at least, serve to show that such marriages, and the experience of isolated communities, are not everywhere in favour of Mr. Huth’s conclusions. Several statements on the subject have, indeed, scarcely any value as direct evidence for the harmfulness of consanguineous marriages, but to two or three considerable weight must be attached.
According to v. Martius, who is a great authority on Brazilian ethnography, it is a well-established fact, observed everywhere, that the smaller and more isolated of the Indian communities, scarcely any members of which marry members of other communities, are much more liable to every kind of deterioration than the larger groups.[2026] “It is probable,” Mr. Bates, another most capable judge, remarks with reference to the savage tribes on the Upper Amazons, “that the strange inflexibility of the Indian organization, both bodily and mental, is owing to the isolation in which each small tribe has lived, and to the narrow round of life and thought, and close intermarriages for countless generations, which are the necessary results. Their fecundity is of a low degree, for it is very rare to find an Indian family having so many as four children, and we have seen how great is their liability to sickness and death on removal from place to place.”[2027] Touching the Isánna Indians, Mr. Wallace asserts that they are said not to be nearly so numerous, nor to increase so rapidly, as the Uaupés; which may perhaps be owing to their marrying with relations, while the latter prefer strangers.[2028] And v. Tschudi supposes that the low fecundity of the Botocudos is caused by their endogamous habits; for when their women marry out of their own horde, especially with whites or negroes, they are generally very fertile.[2029]
The Calidonian Indians of the Isthmus of Darien, according to Mr. Gisborne, are bound never to cross the breed with foreigners; hence intermarriage is very constant, and, as he remarks, the race degenerates.[2030] The Pueblos in New Mexico, too, are said to deteriorate because of their constant intermarriage in the same village.[2031] As regards the Hottentots, Barrow remarks, “The impolitic custom of hording together in families, and of not marrying out of their own kraals, has no doubt tended to enervate this race of men, and reduced them to their present degenerated condition, which is that of a languid, listless phlegmatic people, in whom the prolific powers of nature seem to be almost exhausted.” Few of the women have more than two or three children, and many of them are barren. But this is not the case when a Hottentot woman is connected with a white man. “The fruit of such an alliance,” says Barrow, “is not only in general numerous, but they are beings of a very different nature from the Hottentot.”[2032]
In too early marriages, the licentious habits of both sexes, and the intermarriage of near relatives, the Rev. J. Sibree finds the causes of the infertility of the women of Madagascar.[2033] Among the Garos, the chiefs have, in comparison with the lower classes, degenerated physically, and Colonel Dalton is inclined to think that this degeneration is a result of close interbreeding.[2034] The Lundu Sea Dyaks, according to Sir Spenser St. John, have decreased greatly in numbers—from a thousand families to ten. “They complain bitterly,” he says, “that they have no families, that their women are not fertile; indeed, there were but three or four children in the whole place. The men were fine-looking and the women well-favoured and healthy—remarkably clean and free from disease. We could only account for their decreasing numbers by their constant intermarriages.”[2035] Mr. Foreman thinks that the low intellect and mental debility perceptible in many families among the domesticated natives of the Philippines are due to consanguineous marriages.[2036] Mr. Bachelor connects the rapid decrease of the Ainos with their endogamous habits.[2037] And Mr. Meade remarks, with regard to the Maoris, that one of the principal causes of the diminishing population is said to be their intermarriages, which cause barrenness among the women.[2038]
Of no little interest to us are the Todas of the Neilgherry Hills. Mr. Marshall remarks that, among them, relationship is intimate far beyond that witnessed in any country approaching civilization—“intimate to such a degree, that the whole tribe, where not parents and children, brothers and sisters, are all first cousins, descended from lines of first cousins prolonged for centuries.”[2039] As regards the general appearance of the people, a large proportion of both sexes and of all ages are doubtless in excellent health, and their fecundity, according to Dr. Shortt, is by no means of a low degree.[2040] Nevertheless, the Todas are dying out. In infancy the mortality is so great that, as a rule, there is in each family only a small number of children.[2041] “It is rarely that there are more than two or three children,” says the missionary Metz, “and it is not at all an uncommon thing to find only a single child, while many families have none at all.” The numbers of the Todas have, consequently, for years past been gradually declining, and probably the time is not far distant when they will have passed away.[2042] Of course, we do not know whether this depends upon their close intermarriages, but there is, at any rate, some reason to suspect that this is the case. That the intermarrying has not produced more evil effects on the population, may possibly be owing to the wealth for which the Neilgherry Hills are remarkable, and to their climate, which, for mildly invigorating properties and equable seasonal changes throughout the year, is perhaps unrivalled anywhere within the tropics.[2043]
Another very much in-and-in bred people are the Persians. Among them, husband and wife are generally of the same family, and very often cousins. Yet Dr. Polak who has lived in Persia for nine years, partly as a teacher in the medical school of Teheran, partly as physician to the Shah, and during this residence has had excellent opportunities of acquainting himself with the conditions of the people, has not observed that the diseases which are supposed to result from consanguineous marriages prevail more frequently there than elsewhere. Nor has he found that the Persian women are generally less fertile than others. Yet the families are exceedingly small, as the mortality among children is enormous. Of six, perhaps two as a rule survive, but very often none at all, most of them dying in their second year. Dr. Polak believes, indeed, that, on an average, scarcely more than one living child comes to each woman. A princess in Teheran was looked upon quite as a wonder because she had eight children alive, and the European physician was asked if he ever before, in his own country, had seen a similar case.[2044]