Monogamy more prevalent at the lowest stages of civilization than at somewhat higher stages, pp. 505-508.—Polygyny favoured by social differentiation, pp. 505, _et seq._—The very lowest races either strictly monogamous, or but little addicted to polygyny, pp. 506, _et seq._—Polygyny adopted under the influence of a higher civilization, pp. 507, _et seq._—Monogamy prevails among the man-like apes, p. 508.—Civilization in its higher forms leads to monogamy, pp. 508, _et seq._—Will monogamy be the only recognized form of marriage in the future? pp. 509, _et seq._—Criticism of Mr. McLennan’s theory as to the general prevalence of polyandry in early times, pp. 510-515—The Levirate affords no evidence for this theory, pp. 510-514.—Polyandry always an exception in the human race, pp. 514, _et seq._—It presupposes an abnormally feeble disposition to jealousy, p. 515.—It seems to presuppose a certain amount of civilization, pp. 515, _et seq._—Polyandry an expression of fraternal benevolence, p. 516.—The origin of the group-marriage of the Toda type, _ibid._ CHAPTER XXIII THE DURATION OF HUMAN MARRIAGE The time during which marriage lasts varies, p. 517.—Peoples among whom separation is said to be unknown, _ibid._—Human marriage, as a general rule, not necessarily contracted for life, pp. 518-520.—Divorce dependent upon the husband’s decision, pp. 520, _et seq._—Divorce among a great many peoples exceptional, pp. 521-523.—A man permitted to divorce his wife only under certain conditions, pp. 523-526.—Marriage dissolved by the wife, pp. 526-529.—The causes by which the duration of human marriage is influenced, pp. 529-535.—The duration of marriage among primitive men, p. 535.—The development of the duration of human marriage, pp. 535, _et seq._ CHAPTER XXIV SUMMARY PP. 537-550. AUTHORITIES QUOTED pp. 551-580 INDEX pp. 581-644 THE HISTORY OF HUMAN MARRIAGE INTRODUCTION ON THE METHOD OF INVESTIGATION It is in the firm conviction that the history of human civilization should be made an object of as scientific a treatment as the history of organic nature that I write this book. Like the phenomena of physical and psychical life those of social life should be classified into certain groups, and each group investigated with regard to its origin and development. Only when treated in this way can history lay claim to the rank and honour of a science in the highest sense of the term, as forming an important part of Sociology the youngest of the principal branches of learning.