But even if Mr. McLennan were right in his assumption that savages everywhere used to kill female infants, this would not explain the origin of exogamy. “In time,” he says, “it came to be considered improper, because it was unusual, for a man to marry a woman of his own group.”[1882] But why should such a marriage ever have become unusual? Why should the men have refrained from marrying those women of their own tribe who were not killed? Why should they have made these beings whom they considered so useless, even more useless than they naturally were, by preventing them from becoming mothers of sons who would have increased the strength of the tribe? That the men may have endeavoured to make up the deficiency of women by capturing wives from foreign tribes is conceivable enough; but it is hard to see why intercourse with women of their own tribe should on this account have been prohibited, sometimes even on pain of death. That the horror of incest is innate in the human race seems as improbable to Mr. Herbert Spencer as to Mr. McLennan. According to Mr. Spencer, this feeling is a result of evolution gradually acquired. Primitive groups of men, he says, are habitually hostile. In all times and places victory is followed by pillage; whatever portable things of worth the conquerors find they take. And of course they take women as they take other booty, because women are prized as wives, as concubines, or as drudges. A captured woman, besides her intrinsic value, has an extrinsic value: “like a native wife she serves as a slave, but unlike a native wife, she serves also as a trophy.” Hence members of the tribe thus married to foreign women are held to be more honourably married than those married to native women. If the tribe, becoming successful in war, robs adjacent tribes of their women more frequently, there will then grow up the idea that the now considerable class having foreign wives form the honourable class, and non-possession of a foreign wife will come to be regarded as a proof of cowardice. “An increasing ambition to get foreign wives will therefore arise; and as the number of those who are without them decreases, the brand of disgrace attaching to them will grow more decided; until in the most warlike tribes, it becomes an imperative requirement that a wife shall be obtained from another tribe—if not in open war, then by private abduction.”[1883]