+434+. Proof is lacking also for Durkheim's theory. It is not probable that the totem was regarded as divine in the period in which exogamy arose--by the tribes whose ideas on this point are known the totem is looked on as a friend and an equal but not as a god. And, as is pointed out above, there is no such general religious respect for the clan blood as would forbid sexual intercourse between persons of the same clan. The demand for revenge for the murder of a clansman arises from the sense of clan solidarity and the necessity of self-defense--it is only in this regard that the blood of the clan is regarded as sacred. +435+. Horror of marriage or of sexual intercourse in general, within the prohibited degrees or areas, is universal in low communities; violation of the tribal law on this point is severely punished, sometimes with death. Whence this feeling sprang is not clear.[785] It cannot have arisen from respect for the purity of women or from a belief in the sanctity of the family--intercourse with girls before their marriage is freely allowed, and lending or exchange of wives is common. Magical dangers are supposed to follow on infringement of marriage rules, but, as such results come from violation of any tribal custom, this throws no light on the origin of the feeling of horror in question. Absence of sexual attraction between persons brought up together,[786] though the absence of such feeling is said to have been observed in some of the lower animals, is not assured for savages; its existence in civilized communities is due to the acceptance of the established usage, which makes certain unions impossible, so that they are not considered, and the germ of such a public opinion may perhaps be assumed for early tribes. Probably the horror of incest is a derivation from economic and other situations and laws that arose naturally in early society--it is a habit hardened into an instinct. +436+. Though exogamy differs from totemism in origin and function, the two are often found associated--their conjunction may be said to be the general rule. There are, however, exceptions.[787] Totemic clans are not exogamous in Central Australia, the Melanesian Banks Islands, among the Nandi of East Africa, and the Bakuana of South Africa. On the other hand, exogamy is found without totemism in the tribes just mentioned, among the Todas of Southern India, in Sumatra, among the African Masai and Ashanti, and in Southern Nigeria, and local exogamy among tribes (for example, the Kurnai of Southeast Australia, and the Californian Maidu and Shasta) in which totemic divisions are not perceptible.