Endogamy proper is the rule which allows marriage only be tween members of a section of a tribe and forbids unions between members of two sections. Strict endogamy is rare. It occurs mainly in India where members of the same caste only are al lowed to marry (see Caste and Endogamy). In other parts of India we find a system called hypergamy (q.v.) in which a man is allowed to marry a woman of a lower section in his caste. He may also marry a woman of the same section if other conditions allow this. But a woman may not marry a man of a lower section on penalty of loss of status of her whole family. In some com munities there is competition to secure husbands of high sections.
In primitive communities endogamy is not very widespread. It occurs in tribes where there is a degraded class of artisans or else stratification by rank (Polynesia; Korea, Japan; Trobriand Is lands of Melanesia; Algonkin, Salish of N. America; Masai, Ban yankole, Karanga and other tribes of E. and S. Africa). In such cases we often find endogamy in what might be called an approxi mate form. Indeed such approximate endogamy, as a tendency to marry within the profession, class or rank, is, as an unwritten law, well-nigh universal in primitive and civilized communities.
Another type of endogamy which is very widespread is that associated with religion. In very few religions is marriage outside the group of the faithful permitted. Islam, Judaism, Christianity and Hinduism are cases in point. Primitive religion as a rule need not be intolerant as regards mixed marriages, because there the tribal barriers and lack of communication act with sufficient stringency.
23. The Prohibition of Incest.—The most widely spread and most rigidly enforced qualification to marriage is the set of rules which prohibit unions between the members of the same family. These are known as the rules of incest (q.v.), and play a great part in the constitution of the family (q.v.) and in the regu lation of primitive kinship (q.v.). Incest has become also of great importance in modern psychology through the speculations of Freud and the psychoanalytic school (see PSYCHOANALYSIS).
Although incestuous unions between near relatives are univer sally abhorred and prohibited, the rules differ greatly from one society to another as regards the prohibited degrees as well as the stringency and character of the sanctions. Marriages between mother and son and between father and daughter are universally prohibited by law, custom and moral sentiment. Statements can be quoted, it is true, of tribes among whom more or less irregular unions between parents and children do occur. Thus marriages between mother and son have been reported from the Caribs, Eskimo, Pioje, Tinne of America; Minahassa of Celebes and Kalang of Java; New Caledonians; and the Banjoro of Africa. Again unions between father and daughter are said to occur among the Minahassa of Celebes, Karens of Burma, and in the Solomon, Marshall and Pelew Islands of Oceania. Even better attested are the marriages between brother and sister (Marshall Islands and Hawaii; ancient Irish, Egyptian and Inca royal families).
When we go beyond the family group, the prohibitions of mar riage between uncles and nieces, aunts and nephews, first and second cousins, and so on, vary greatly. In some communities certain of these unions are explicitly encouraged and regarded as desirable; in others forbidden. About preferential marriages be tween relatives we have already spoken (see above, 7). Exten sive prohibitions of marriage between distant kindred exist, besides the Western Christian civilizations also among a number of other tribes and cultures (Salish, Eskimo, Pipites of Salvador, Aztecs, Araucanians, Abipones, Ona, Yahgan of America; Koryak, Yukaghir, Kalmuck of N.E. Asia; Torres Straits Islanders, Mekeo, Polynesians of Oceania; S.E. Bantu of Africa).
24. is the system under which far larger groups of people are regarded as related to each other and their members forbidden to intermarry. It is found mainly in associa tion with the classificatory nomenclature of kinship terms and the clan organisation (cf. also EXOGAMY, KINSHIP, RELATIONSHIP