72 evolution: the ages and tomorrow 



which mutual aid exists among animals. He wrote of cases 

 where sentinels are posted to warn feeding herds of possible 

 danger; of herds of mammals in which the strongest indi- 

 viduals, the males, place themselves on the outside of the 

 massed herds when wolves attacked; of wolves which hunt 

 in packs; of ravens and pelicans feeding their blind fellows; 

 and of monkeys of both sexes adopting and solicitously car- 

 ing for orphaned young. Darwin had a strong feeling that 

 man could, if he but used his powers of reason, extend his 

 social instincts and sympathies to his fellows of all nations 

 and races. 



Prince Kropotkin's uncritical observations on mutual aid 

 have been borne out, in principle, by the researches of the 

 intervening years. Kropotkin saw a world of mutual aid. 

 Wherever natural conditions were unfavorable, climate too 

 rigorous, food too scarce, cooperation became an important 

 factor in survival. He was correct in assuming that social 

 life occurs on all levels and that association began with the 

 dawn of animal life. Mutual aid, he thought, was as strong a 

 factor in evolution as the struggle between the classes, and 

 certainly greater than struggle and competition within a 

 species. The "fittest" survived, but the fittest were those 

 who had acquired habits of mutual aid. He and others saw 

 that many adaptations in the animal kingdom are aimed at 

 removing, as far as possible, the struggle within species- 

 adaptations such as the storing of food by ants, the migra- 

 tions of birds, the winter sleep which begins when food be- 

 comes scarce. 



Competition in the noncooperative sense is always the 

 easy surface observation. In most cases the observer must 

 look carefully for the fuller behavior pattern, before the im- 

 pression generally held now emerges that mutual aid, at least 

 to some degree, is universal in the animal kingdom. Even in 

 the lowest forms we sometimes see spectacular instances. So- 

 cial amoebae of the group of slime molds ( Acrasiaceae) are 

 individual, microscopic, single cells, living freely and inde- 



