If the family is a persistent type the tribe may also be compared to the modern state; it is, in most parts of the world, no less territorial in its nature; membership of it does not depend among the Australians on any supposed descent from a common ancestor; and though residence plus possession of a common speech is mentioned by Howitt as the test of tribe, it is possible in Australia, under certain conditions[1], to pass from one tribe to another in such a way that we seem reduced to residence as the test of membership.  This change of tribe takes place almost exclusively where tribes are friendly, so far as is known; and we may doubt whether it would be possible for a stranger to settle, without any rite of adoption, in the midst of a hostile or even of an unknown tribe; but this is clearly a matter of minor importance, if adoption is not, as in North America, an invariable element of the change of tribe.  Although membership of a tribe is thus loosely determined, tribesmen feel themselves bound by ties of some kind to their fellow-tribesmen, as we shall see below, but in this they do not differ from the members of any modern state.

But in Australia the importance of the tribe, save from an economic point of view, as joint owner of the tribal land, is small compared with the part played in the lives of its members by the intratribal associations, whose influence is recognised without, as within the tribe.  These associations are of two kinds in the lowest strata of human society; in each case membership is determined by birth and they may therefore be distinguished as natal associations.  In the one case, the kinship groups such as totem kins, phratries, etc., an individual remains permanently in the association into which he is born, special cases apart, in which by adoption he passes out of it and joins another by means of a legal fiction[2].  The other kind of association, to which the name age-grades is applied, is composed of a series of grades, through which, concomitantly with the performance of the rites of initiation obligatory on every male member of the community, each man passes in succession, until he attains the highest.  In the rare cases where an individual fails to qualify for the grade into which his coevals pass, and remains in the grade of “youth” or even lower grades, he is by birth a member of one class and does not remain outside the age-grades altogether.

In the element of voluntary action lies the distinction between age-grades and secret societies, which are organised on identical or similar lines but depend for membership on ceremonies of initiation, alike in the lowest as in the highest grade.  Such societies may be termed voluntary.  The differentia between the natal and the voluntary association lies in the fact that in the former all are members of one or other grade, in the latter only such as have taken steps to gain admission, all others being simply non-members.