These criticisms have not gone unchallenged. More recent and more detailed examination of the classificatory nomenclatures has thrown new light on their meaning; although their origin in promiscuity or "group-marriage" has not been conclusively established. Thus Cunow, who in general accepts the former existence of group-marriage among various peoples, and even finds traces of it in Australia,[218] denies that the Australian class-nomenclatures are derived from original group-relations;[219] nor are they, as Westermarck believes, ever employed as mere empty terms of polite or respectful address.[220] The class-systems arose in a very early recognition of three generations or stages of seniority, in order to hinder sexual relations between relatives in the ascending and descending line.[221] For this reason, and because of the existence among some backward tribes of significant terms of kinship, individual marriage must as a general rule have existed among the Australian natives from the "earliest times."[222] Thus, "in its original form," the author concludes, "the division into classes is a striking confirmation of Morgan's theory, that the first step in the development of systems of relationship consists in the prevention of sexual union between parents and children in the wide sense."[223] For the same reason it follows that intermarriage between the nearest collateral relatives may not have been excluded. [218] The so-called "Pirauru marriage" of the Dieri tribe (HOWITT, in _Trans. R. S. Victoria_, I, Part II, 1899, 96) and the "Dilpamali marriage" of the Kunandaburi tribe (CUNOW, _Australneger_, 163). Practically the same is the Piraungaru custom of the Urabunna tribe which SPENCER AND GILLEN, _Native Tribes of Central Australia_, 61 ff., regard as a "modified form of group-marriage." [219] CUNOW, _op. cit._, 161, 163-65. [220] _Idem_, _Australneger_, 176. [221] On the three _Altersclassen_ or _Altersschichtungen_, see _ibid._, 25 ff. The present class-system of the Kamilaroi, the author believes, is not older than the rise of the gentile organization. "Originally the division into classes by no means served, as Morgan and Fison assume, to exclude sexual intercourse between near collateral kindred, but to prevent cohabitation between relatives in the ascending and descending line, between parents and children, uncles and nieces, aunts and nephews, etc." _Cf._ as to the main point the somewhat similar views of HELLWALD, _Die mensch. Familie_, 158 ff.; LIPPERT, _Kulturgeschichte_, I, 81-83; and KAUTSKY, _Kosmos_, XII, 196-98. [222] CUNOW, _op. cit._, 161, 162: Among backward tribes parents are distinguished from parents' brothers and sisters; and own children from the children of own brothers and sisters. [223] _Ibid._, 25. See the somewhat similar conclusion of ATKINSON, _The Primal Law_, 280-94; and compare the criticism of CUNOW by LANG, _Social Origins_, 37, 112-18.