Among birds, marriage is generally concluded for life; among mammals rarely for more than a year, with the exception of the anthropoid apes and man.

The duration of marriage varies enormously in man. Among the Andamanese, the Weddas, certain Papous, marriage can only cease with death. Among the North American Indians, on the contrary, it is only concluded for a limited period. Among the Wyandottes the custom exists of trial marriages for several days. In Greenland, divorce often takes place at the end of six months. Among the Creeks marriage does not last more than a year. In this way is constituted a kind of polygamy by succession or limited monogamy, which results in the father not knowing his children.

Among the Botocudos, marriage is performed without ceremonies and only lasts a short time; it can be broken off on the slightest pretext, for the pleasure of changing; divorce then becomes as frequent as marriage. This is also the case in Queensland, Tasmania and the Samoan islands. Among the Dyaks and Cingalese, quite young men and women have already had several wives or husbands; a man often marries and deserts the same woman several times, to take others during the intervals. Among the Mantras there are men who have been married forty or fifty times.

In Persia a woman may marry for periods varying from one hour to ninety-nine years. In Egypt similar customs are met with; a monthly change is allowed, so that a man may marry twenty or thirty times in two years. Among the Maues of Sahara the women consider it fashionable to marry as often as possible, and a long married life is considered by them as vulgar. The Abyssinians, negroes, etc., marry on trial or for limited periods. Among the Greeks, Romans and ancient Germans, divorce was very frequent.

In nearly all savage tribes, and in a number of civilized people the man possesses an unlimited right of rejection. The Hovas compare marriage to a loosely tied knot. Among the ancient Jews, Romans, Greeks and Germans, discontent of the husband was a sufficient reason for rejection. On the contrary, among a number of savage races (Westermark mentions about twenty-five) rejection and divorce are extremely rare and marriage lasts for life.

It is especially where there are children that divorce is rare. With most races, sterility of the wife and adultery constitute the principal causes of legal divorce.

Among civilized races marriage for life is much more common than with savages. This was the case with the Aztecs, etc. Among the Chinese there exist seven reasons for divorce: sterility, unchastity, negligence toward parents-in-law, talkativeness, desertion, ill-temper and chronic disease. In Japan the laws are similar, but in spite of this divorce is rare in China and Japan.

In Christian countries divorce was formerly permitted and was only prohibited by the Council of Trent. The modern Catholic says: "Man must not separate what God has united." Among many savages, on the contrary, divorce is left to the free will of the married couple. Elsewhere it is sometimes the man, sometimes both husband and wife who have the right to exact divorce for divers reasons, such as drunkenness, adultery, prodigality, etc. In Europe, as elsewhere, it is the desire for change which is the most common cause of divorce.

Children constitute the surest cement against conjugal separations. With most savages the rejected wife regains not only her dot, but also part of the common property, or even the whole of it. On the contrary, the purchase value of the wife is only as a rule returned to the husband when sterility, adultery or other grave reasons are the causes of divorce. It results from this that divorce is always very rare among peoples where the women are very dear.

The right of the children after divorce varies a good deal in different races; sometimes they are adjudged to the husband, sometimes to the wife. Divorced women often become prostitutes, for example, among the Chinese and Arabs. As a rule, marriages for love are more lasting than others, especially when the couple were acquainted before marriage.