Although this theory furnishes a plausible explanation of certain Biblical facts, such as the marriage of Cain (_Gen. 4:17_), Cain’s fear that men would slay him (_Gen. 4:14_), and the distinction between “_the sons of God_” and “_the daughters of men_” (_Gen. 6:1, 2_), it treats the Mosaic narrative as legendary rather than historical. Shem, Ham, and Japheth, it is intimated, may have lived hundreds of years apart from one another (409). Upon this view, Eve could not be “_the mother of all living_” (_Gen. 3:20_), nor could the transgression of Adam be the cause and beginning of condemnation to the whole race (_Rom. 5:12, 19_). As to Cain’s fear of other families who might take vengeance upon him, we must remember that we do not know how many children were born to Adam between Cain and Abel, nor what the age of Cain and Abel was, nor whether Cain feared only those that were then living. As to Cain’s marriage, we must remember that even if Cain married into another family, his wife, upon any hypothesis of the unity of the race, must have been descended from some other original Cain that married his sister.
See Keil and Delitzsch, Com. on Pentateuch, 1:116—“The marriage of brothers and sisters was inevitable in the case of children of the first man, in case the human race was actually to descend from a single pair, and may therefore be justified, in the face of the Mosaic prohibition of such marriages, on the ground that the sons and daughters of Adam represented not merely the family but the genus, and that it was not till after the rise of several families that the bonds of fraternal and conjugal love became distinct from one another and assumed fixed and mutually exclusive forms, the violation of which is sin.” Prof. W. H. Green: “_Gen. 20:12_ shows that Sarah was Abraham’s half-sister;...the regulations subsequently ordained in the Mosaic law were not then in force.” G. H. Darwin, son of Charles Darwin, has shown that marriage between cousins is harmless where there is difference of temperament between the parties. Modern palæontology makes it probable that at the beginning of the race there was greater differentiation of brothers and sisters in the same family than obtains in later times. See Ebrard, Dogmatik, 1:275. For criticism of the doctrine that there were men before Adam, see Methodist Quar. Rev., April, 1881:205-231; Presb. Rev., 1881:440-444.