This highly elaborate and artificial system was no doubt, as stated by Sir J.G.Frazer, devised for the purpose of preventing the intermarriage of parents and children belonging to different clans where there are four sub-classes, and of first cousins where there are eight sub-classes.

[166] The class system, however, would not appear to have been the earliest form of exogamy among the Australian tribes.

Its very complicated character, and the fact that the two principal classes sometimes do not even have names, seem to preclude the idea of its having been the first form of exogamy, which is a strong natural feeling, so much so that it may almost be described as an instinct, though of course not a primitive animal instinct.

And just as the totem clan, which establishes a sentiment of kinship between people who are not related by blood, was prior to the individual family, so exogamy, which forbids the marriage of people who are not related by blood, must apparently have been prior to the feeling simply against connections of persons related by blood or what we call incest.

If the two-class system was introduced in Australia to prohibit the marriage of brothers and sisters at a time when they could not recognise each other in adult life, then on the introduction of personal names which would enable brothers and sisters to recognise and remember each other, the two-class system should have been succeeded by a modern table of prohibited degrees, and not by clan exogamy at all.