From the very beginning there has been no such thing as unmitigated individual struggle among animals. Nowhere in nature does pure individualism exist in the sense that the individual animal struggles alone, except perhaps in a few solitary species which are apparently on the way to extinction. The assumption of such a primitive individual struggle has been at the bottom of many erroneous views of human society. The primary conflict is between species. A secondary conflict, however, is always found between the members of the same species. Usually this conflict within the species is a competition between groups. The human species exactly illustrates these statements. Primitively its great conflict was with other species of animals. The supremacy of man over the rest of the animal world was won only after an age-long conflict between man and his animal rivals. While this conflict went on there was apparently but little struggle within the species itself. The lowest groups of which we have knowledge, while continually struggling against nature, are rarely at war with one another. But after man had won his supremacy and the population of groups came to increase so as to encroach seriously upon food supply, and even on territorial limits of space, then a conflict between human groups, which we call war, broke out and became almost second nature to man. It needs to be emphasized, however, that the most primitive groups are not warlike, but only those that have achieved their supremacy over nature and attained considerable size. In other words, the struggle between groups which we call war was occasioned very largely by numbers and food supply. To this extent at least war primitively arose from economic conditions, and it is remarkable how economic conditions have been instrumental in bringing about all the great wars of recorded human history. The conflict among human groups, which we call war, has had an immense effect upon human social evolution. Five chief effects must be noted. (1) Intergroup struggle gave rise to higher forms of social organization, because only those groups could succeed in competition with other groups that were well organized, and especially only those that had competent leadership.