Another cause of polygamy is man's natural desire for change. The negroes of Angola exchange wives. The instinct of procreation, love of glory and riches coöperate with the sterility of many women in propagating polygamy. Certain races only tolerate it when the woman is sterile, or has only daughters, which clearly proves that it is based on the fear of remaining without male descendants.
On the whole, savage women are less fecund than civilized, owing to their long continence during the two or four years nursing of each child. If we add to this the high infant mortality, we can understand how polygamy becomes among these people a means of reproduction in the struggle for existence, and even in African races a natural law. A native of Central Africa may have a hundred wives, who also act as servants and retainers. In this case polygamy is the expression of pomp and wealth. It is especially developed in agricultural peoples owing to the value of the woman's labor. On the other hand it is impossible among nomadic tribes. In Dahomey the king had thousands of wives, the nobility hundreds, the simple citizen a dozen and the soldier none at all.
Jealousy and rivalry among the wives is not always the rule in polygamous families. In equatorial Africa the wives themselves incline to polygamy and regard a rich man who restricts the number of his wives as miserly. Livingstone relates that the women of Makololo declared they would not live in monogamous England, for any respectable man should prove his wealth by the number of his wives. We must not forget that among most savages the moral conception of good and evil are confounded with that of riches and poverty. In reality, the supernumerary wives bought by a polygamist are simply slaves. His power and authority do not easily allow jealousy among them; nevertheless suicide sometimes occurs among the old wives who have been passed over in favor of younger ones. Sometimes they kill their children at the same time. Among the Indians of Terra del Fuego a hut containing three or four women often resembles a battlefield. We have already pointed out the way in which jealous Fiji women cut off the noses of their rivals. Among the Islamites and Hindus intrigue and jealousy are common with the women; the same in Abyssinia, among the Hovas of Madagascar and the Zulus. The Hova term for polygamy is _rafy_, which signifies adversary. To prevent the jealousy of his wives the polygamous man often places them in separate houses; this is common among the South American Indians.