On the other hand, Emin Pasha tells us that, among the Mádi in Central Africa, “should a girl become pregnant, the youth who has been her companion is bound to marry her, and to pay to her father the customary price of a bride.”[115] Burton reports a similar custom as prevailing among peoples dwelling to the south of the equator.[116] Among many of the wild tribes of Borneo, there is almost unrestrained intercourse between the youth of both sexes; but, if pregnancy ensue, marriage is regarded as necessary.[117] The same, as I am informed by Dr. A. Bunker, is the case with some Karen tribes in Burma. In Tahiti, according to Cook, the father might kill his natural child, but if he suffered it to live, the parties were considered to be in the married state.[118] Among the Tipperahs of the Chittagong Hills,[119] as well as the peasants of the Ukraine,[120] a seducer is bound to marry the girl, should she become pregnant. Again, Mr.Powers informs us that, among the Californian Wintun, if a wife is abandoned when she has a young child, she is justified by her friends in destroying it on the ground that it has no supporter.[121] And among the Creeks, a young woman that becomes pregnant by a man whom she had expected to marry, and is disappointed, is allowed the same privilege.[122] It might, however, be supposed that, in man, the prolonged union of the sexes is due to another cause besides the offspring’s want of parental care, _i.e._, to the fact that the sexual instinct is not restricted to any particular season, but endures throughout the whole year. “That which distinguishes man from the beast,” Beaumarchais says, “is drinking without being thirsty, and making love at all seasons.” But in the next chapter, I shall endeavour to show that this is probably not quite correct, so far as our earliest human or semi-human ancestors are concerned. CHAPTER II A HUMAN PAIRING SEASON IN PRIMITIVE TIMES Professor Leuckart assumes that the periodicity in the sexual life of animals depends upon economical conditions, the reproductive matter being a surplus of the individual economy. Hence he says that the rut occurs at the time when the proportion between receipts and expenditure is most favourable.[123] Though this hypothesis is accepted by several eminent physiologists, facts do not support the assumption that the power of reproduction is correlated with abundance of food and bodily vigour. There are some writers who even believe that the reverse is the case.[124]