The point is that marriage, or what constitutes marriage, exists among birds and animals, and that it antedates history as a social institution among men. Another fact which we must concede, if we are just, is that marriage apparently knows no systematic and upward trend. There is, in fact, no determined evolution toward a definite and conclusive practice of monogamy, although the monogamic custom is recognized as the evolutionary type among the civilized races of today. Nevertheless, it would be folly to imply that a strict monogamy obtains in the letter of the word, or that social exigencies might not reinstate polygamy as a legalized custom. Passing over those forms of mating, which may be classed as sex-promiscuity, such, for example, as exist among the Esquimaux, and also among the Dyaks, of Borneo, where a "contract" is made for a night by the simple expediency of the man and the woman exchanging head-gear, we come to one of the earliest and most general forms of marriage among primitive peoples, where the parents arranged a marriage between their children for reasons of personal profit. In these instances, neither the youth nor the girl was consulted and generally did not meet until they met to consummate the marriage. In fact, they seemed not to have any preferences. These marriages were easily broken, unless children resulted therefrom, when there seems to have developed a sense of obligation to the offspring to continue the family. Marriage by capture grew out of the matriarchal system and came as the very natural revolt of the male from the female rule, in which he had no rights and no home with his spouse. Since the gens of the family was the first consideration and this was maintained by the female heads of a clan, there was nothing left for the male to do, if he would be a factor in the community, but to steal his wife from her family, and establish a family life of his own. Thus the female became the possession of the male, by his right of capture and defense. Inspired by the thirst for further invasions, the male gradually acquired not only one, but many wives, which constituted his "possessions," from the fact that he had earned them by right of conquest, conquest being not only the savage but also the civilized idea of "earning." Indeed, our modern marriages reveal a degree of savagery in this respect, which is not suspected by the casual observer. The almost general observance of what has come to be known in legal jurisprudence as "the unwritten law," which permits a man to go unpunished when he kills another man whom he believes to have been on terms of intimacy with his wife, is a tacit admission of a man's vested rights in his wife's person.