The survey of Australian customs and terms of relationship leads us to the conclusion that the former, so far from proving the present or even former existence of group marriage in that continent, do not even render it probable; on the latter no argument of any sort can be founded which assumes them to refer to consanguinity, kinship or affinity.  It is therefore not rash to say that the case for group marriage, so far as Australia is concerned, falls to the ground.  Even were it otherwise, even were group marriage proved for Australia or for any other part of the world, we should still be far from having established promiscuity and group marriage as a stage in the general history of mankind.  For that at least a scheme of development is needed.  Even were the arguments in favour of the group marriage hypothesis much stronger, its supporters might reasonably be asked to give us something more than assertion and reassertion without any attempt to show in detail the process of evolution.  To take an example from another sphere, it may safely be said that the general theory of evolution would find few supporters if it were not possible to trace some existing species and genera back to some generalised type in the past.  At present the position of a supporter of the theory of primitive promiscuity and group marriage is analogous to that of an evolutionist who can only point to a few more or less useless peculiarities in the anatomy of man without being able to show resemblances between them and the corresponding portions of fossil or actually existing anthropoids.  He calls them “vestiges[197]” and insists that homo is descended from a generalised anthropoid.  The mere assertion of the vestigial character of such bones or organs would hardly carry conviction unless they could be shown to exist in some anthropoid in a more fully developed state.  Similarly the arguments for promiscuity and group marriage suffer from incurable weakness, and would so suffer, even were the basis far more reliable than I have shown to be the case, unless and until it has been shown by what process and for what reasons man took each upward step.  So far only one writer has attempted, and that nearly thirty years ago, to trace the course of human development on the hypothesis of primitive promiscuity, and his scheme is a house of cards.

The student of sociology is at a disadvantage compared with the zoologist in not being able to unearth his fossils for comparison with living forms.  He must therefore trace the relationship between living forms, and, in seeking to discover the earlier stages of human progress, rely in part on the sociology of the higher mammals, in part on the possibility of showing a logical scheme of human development.  When he examines the living forms he is of course unable to say whether actually existing savage institutions are in the main line of human progress or merely bye-paths embryological or teratological.  It may be possible to show that group marriage exists somewhere on the earth at the present time.  Even if this is so, the theory of primitive promiscuity and group marriage as stages in the general history of mankind remain mere baseless guesses until we have a systematic account both of the causes which led to the various steps, and of the processes by which the various stages were reached.