(_c_) All savages live by custom; gregarious animals have their customs; and in the primitive hunting-pack customs must have been early established as “conditions of gregariousness.” M. Salomon Reinach, indeed, thinks that the anthropoid probably became human as the result of inventing taboos, especially in sexual relations; there was economy of nervous energy in the direction of the senses, and consequent enrichment of the intellect.[63] His hypothesis does not carry us far, perhaps, into the particulars of human form and faculty; but it contains this truth, that without the growth of customs there could have been no progress for human nature; and it certainly points to the probability that some custom was early established with regard to marriage. In Prof. Westermarck’s opinion our species was originally monogamous.[64] Supposing this to have been the custom, as it is amongst many Primates, could it have persisted after the formation of the hunting-pack? According to Mr. Thompson Seton, wolves pair “probably for life”;[65] but this is disputed; and so it is whether or no the male of a seasonal pair takes part in caring for the puppies.[66] Of the primitive human stock one may say that whilst, on the one hand, the association of many males and females in the same pack may have tended to break up the family, on the other hand, the long youth of the children and the parental care generally characteristic of Primates would have tended to preserve it; that the practice of pairing requires the largest number of males (setting aside polyandry), and lessens quarrelling, and is therefore favourable to the strength of the pack; and that any custom may have been established that was most favourable to the species in its new life. The least probable of all conditions is promiscuity; for the rearing of children with their ever-lengthening youth must have been difficult, taxing the care of both parents.