It has lately become a fashion to deny the existence of this early stage of human sex life, in order to spare us this "shame." Apart from the absence of all direct proof, the example of the rest of animal life is invoked. From the latter, Letourneau (Evolution du mariage et de la famille, 1888) quoted numerous facts, alleged to prove that among animals also an absolutely unlimited sexual intercourse belongs to a lower stage. But I can only conclude from all these facts that they prove absolutely nothing for man and the primeval conditions of his life. The mating of vertebrates for a lengthy term is sufficiently explained by physiological causes, e. g., among birds by the helplessness of the female during brooding time. Examples of faithful monogamy among birds do not furnish any proofs for men, for we are not descended from birds. And if strict monogamy is the height of virtue, then the palm belongs to the tapeworm that carries a complete male and female sexual apparatus in each of its 50 to 200 sections and passes its whole lifetime in fertilizing itself in every one of its sections. But if we confine ourselves to mammals, we find all forms of sexual intercourse, license, suggestions of group marriage, polygamy and monogamy. Only polyandry is missing;[8] that could be accomplished by men only. Even our next relations, the quadrumana, exhibit all possible differences in the grouping of males and females. And if we draw the line still closer and consider only the four anthropoid apes, Letourneau can only tell us, that they are now monogamous, now polygamous; while Saussure contends according to Giraud-Teulon that they are monogamous. The recent contentions of Westermarck[9] in regard to monogamy among anthropoid apes are far from proving anything. In short, the information is such that honest Letourneau admits: "There exists no strict relation at all between the degree of intellectual development and the form of sexual intercourse among mammals." And Espinas says frankly:[10] "The herd is the highest social group found among animals. It seems to be composed of families, but from the outset the family and the herd are antagonistic; they develop in directly opposite ratio." It is evident from the above that we know next to nothing of the family and other social groups of anthropoid apes; the reports are directly contradictory. How full of contradiction, how much in need of critical scrutiny and research are the reports even on savage human tribes! But monkey tribes are far more difficult to observe than human tribes. For the present, therefore, we must decline all final conclusions from such absolutely unreliable reports.