superior advantages of outbreeding. The largeness of the result would be manifestly out of proportion to the cause, and it would seem that although we may allow some considerable influence to this factor, we have to admit that it must be supplemented by some other cause or causes of appreciable magnitude[253]. [Sidenote: Influence of non-sexual factors] (4) According to one type of explanation (_e. g._ that held by Wundt[254]) the horror of incest is not the cause of exogamy, but the consequence of it--the origin of exogamy itself being due to some other influences only indirectly connected with the sex life. Of such theories of the origin of exogamy a number have been put forward by eminent authorities. Thus McLennan[255], the discoverer of both Totemism and Exogamy, held the view that exogamy was a consequence of the wide prevalence of marriage by capture; this latter being itself a result of the preponderance of the male sex over the female in primitive communities and of the general condition of hostility existing between neighbouring tribes. Herbert Spencer[256] similarly thought that exogamy arose from marriage by capture, men belonging to successful tribes nearly always acquiring their brides in this way, so that it eventually became a disgrace to marry within the tribe. Lord Avebury[257], believing that group marriage or promiscuity was the rule in primitive society, suggests that women taken in war belonged to their individual captor, marriage in a narrow sense being thus exogamous from the start. Kohler[258] believes on the contrary, that exogamy arose as a means of bringing about inter-tribal friendships or alliances. Andrew Lang[259] has suggested that exogamy is due to the fact that the younger brothers of a family were frequently driven out by the stronger and older ones in order to ward off any want that might arise from the living together of a large number of brothers and sisters--the younger brothers being then obliged to marry outside the family group. [Sidenote: Such factors cannot fully explain exogamy]