"Nature must deepen the result by extending it to the time before marriage.... Courtship, with its vivid perceptions and quickened emotions, is a great opportunity for evolution; and to institute and lengthen reasonably a period so rich in impression is one of its latest and brightest efforts." XI. SEXUAL TABOOS If a law were passed compelling every man living in Rochester, N.Y., who wanted a wife to get her outside of that city, in Buffalo, Syracuse, Utica, or some other place, it would be considered an outrageous restriction of free choice, calculated to diminish greatly the chances of love-matches based on intimate acquaintance. If such a law had existed for generations and centuries, sanctioned by religion and custom and so strictly enforced that violation of it entailed the danger of capital punishment, a sentiment would have grown up in course of time making the inhabitants of Rochester look upon marriage within the city with the same horror as they do upon incestuous unions. This is not an absurd or fanciful supposition. Such laws and customs actually did prevail in this very section of New York State. The Seneca tribe of the Iroquois Indians was divided into two phratries, each of which was again subdivided into four clans, named after their totems or animals; the Bear, Wolf, Beaver, and Turtle clans belonging to one phratry, while the other included the Deer, Snipe, Heron, and Hawk clans. Morgan's researches show that originally an Indian belonging to one phratry could marry a woman belonging to the other only. Subsequently the line was drawn less strictly, but still no Indian was allowed to marry a squaw of his own clan, though there might be no blood, relationship between them. If an Algonkin married a girl of his clan he committed a crime for which his nearest relatives might put him to death. This law has prevailed widely among the wild races in various parts of the globe. McLennan, who first called attention to its prevalence and importance, called it exogamy, or marrying-out. What led to this custom is not known definitely; nearly every anthropologist has his own theory on the subject.[134] Luckily we are not concerned here with the origin and causes of exogamy, but only with the fact of its existence. It occurs not only among barbarians of a comparatively high type, like the North American Indians, but among the lowest Australian savages, who put to death any man who marries or assaults a woman of the same clan as his. In some Polynesian islands, among the wild tribes of India as well as the Hindoos, in various parts of Africa, the law of exogamy prevails, and wherever it exists it forms a serious obstacle to free choice--_i.e._, free love, in the proper sense of the expression. As Herbert Spencer remarks,