Backofen and Morgan have thoroughly investigated these relations. Backofen carried on his investigations by a profound study of ancient writings, with the purpose of gaining an understanding of various phenomena presented in mythology and ancient history, that impress us strangely and yet show similarity with facts and occurrences of later days, even down to the present time. Morgan carried on his investigations by spending decades of his life among the Iroquois Indians in the State of New York, whereby he made new and unexpected observations of the modes of family life and system of relationship prevailing among them, and these observations served as a basis to place similar observations, made elsewhere, in the proper light. Backofen and Morgan discovered, independently from one another, that in primeval society the relations of the sexes differed vastly from those prevalent during historic times and among modern, civilized nations. Morgan discovered, furthermore, as a result of his long sojourn among the Iroquois of North America, and his comparative studies to which these observations led him, that all existing primitive peoples have family relations and systems of relationship that differ markedly from our own, but which must have prevailed generally among all peoples at a remote period of civilization. At the time when Morgan lived among the Iroquois, he found that among them existed a monogamous marriage, easily dissolved by either side, termed by him the “pairing family.” But he also found that the terms of relationship as father, mother, son, daughter, brother, sister, although there could be no doubt in our minds as to whom such terms should apply, were not used in their ordinary sense. The Iroquois addresses as sons and daughters not only his own children, but also those of all his brothers, and these--his brothers’ children--call him father. On the other hand, the Iroquois woman does not only call her own children sons and daughters, but also those of all her sisters, and again all her sisters’ children call her mother. But the children of her brothers she calls nephews and nieces, and these call her aunt. Children of brothers call one another brothers and sisters, and so do children of sisters. But the children of a woman and her brother call each other cousins. The curious fact then presents itself that the terms of relationship are not determined by the actual degrees of relationship, but the sex of the relative.