The quotation from Espinas, however, offers a better clue. Among higher animals, the herd and family are not supplements of one another, but antitheses. Espinas demonstrates very nicely, how the jealousy of the males loosens or temporarily dissolves every herd during mating time. "Where the family is closely organized, herds are formed only in exceptional cases. But wherever free sexual intercourse or polygamy are existing, the herd appears almost spontaneously.... In order that a herd may form, family ties must be loosened and the individual be free. For this reason we so rarely find organized herds among birds.... Among mammals, however, we find groups organized after a fashion, just because here the individual is not merged in the family.... The rising sense of cohesion in a herd cannot, therefore, have a greater enemy than the consciousness of family ties. Let us not shrink from pronouncing it: the development of a higher form of society than the family can be due only to the fact that it admitted families which had undergone a thorough change. This does not exclude the possibility that these same families were thus enabled to reorganize later on under infinitely more favorable circumstances."[11] It becomes apparent from this, that animal societies may indeed have a certain value in drawing conclusions in regard to human life--but only negatively. The higher vertebrate knows, so far as we may ascertain, only two forms of the family: polygamy or pairs. In both of them there is only one grown male, only one husband. The jealousy of the male, at the same time tie and limit of the family, creates an opposition between the animal family and the herd. The latter, a higher social form, is here rendered impossible, there loosened or dissolved during mating time, and at best hindered in its development by the jealousy of the male. This in itself is sufficient proof that the animal family and primeval human society are irreconcilable; that ancient man, struggling upward from the animal stage, either had no family at all or at the most one that does not exist among animals. A being so defenceless as evolving man might well survive in small numbers though living in an isolated state, the highest social form of which is that of pairs such as Westermarck, relying on hunter's reports, attributes to the gorilla and the chimpanzee. Another element is necessary for the elevation out of the animal stage, for the realization of the highest progress found in nature: the replacing of the defencelessness of the single individual by the united strength and co-operation of the whole herd. The transition from beast to man out of conditions of the sort under which the anthropoid apes are living to-day would be absolutely unexplainable. These apes rather give the impression of stray sidelines gradually approaching extinction, and at all events in process of decline. This alone is sufficient to reject all parallels between their family forms