SOCIAL EVOLUTION AS A BIOLOGICAL PROCESS 271 



inchoate tribe must not treat his confreres as he might 

 a man of another group ; robbery and murder within 

 the limits of the small association are detrimental to 

 communal interests, though they may remain unchecked 

 if the victims are strangers. Cooperation for mutual 

 offense and defense makes the group stronger than its 

 constituent family units taken singly, and every man 

 of such a tribe gains something by looking out for others 

 as well as for himself. By natural selection alone the 

 bonds of union would be strengthened in direct pro- 

 portion to the subordination of individual interest 

 to group welfare, and to the amount of altruistic 

 action that in a true sense grows out of purely selfish 

 conduct. 



But when such a primitive biological association forms 

 and grows, an opportunity arises for increasing the 

 effectiveness of the whole group by differentiation. 

 Some of the men are stronger in battle and they soon 

 become the chief warriors ; others prove to be more 

 skilful in the hunt or in the construction of canoes and 

 weapons. Just as among the insects, the hunter seeks 

 food not only for himself but for the warriors, who in 

 their turn defend themselves, but do not cease fighting 

 when they have disposed of their own enemies if foes 

 of their comrades still survive. The barbarous state of 

 society thus arises, and the division of labor brought 

 about during its origin makes it possible and indeed 

 essential for many family units to remain together for 

 mutual good. The union is stable and efficient, how- 

 ever, only if the individual suppresses his own selfish 

 inclinations, suspending private quarrels when public 

 wars are toward, and acting at all times in concert with 



