SEX AND SOCIAL RELATIONS 211 



danger to happiness because it runs counter to the 

 facts of life. 



It is shocking to the conventionally minded to 

 realize that a sexual element may enter into an other- 

 wise platonic friendship between one member of a 

 married couple and an outsider of opposite sex. 

 But let us not deceive ourselves on this vital point. 

 The history of human marriage plainly shows that 

 the relative considerateness now shown by men of 

 the highest civilization toward women, in respect 

 to their desire for sexual faithfulness, is a late devel- 

 opment and, therefore, one that is easily lost. The 

 motives that have led to monogamy belong in two 

 distinct groups, motives based on ordinary self- 

 interest and motives based on a refined form of 

 altruistic feeling. Monogamy appears to have been 

 one of the most primitive forms of marriage, but it 

 may be confidently assumed that this early monog- 

 amy was ;due almost wholly to practical reasons. 

 In rude communities, where life is maintained chiefly 

 by hunting, men have few inducements to take to 

 themselves many wives, especially as the labor of 

 women has little value under such conditions. In a 

 higher state of civilization, where people live in 

 comparatively fixed communities and till the soil, 

 polygamy becomes more attractive to the males. 

 This is because it offers them the services of many 

 persons as laborers, the opportunity of raising large 

 families (thus increasing the influence of the head of 

 the family in his tribe), and varied sexual gratifica- 



