Natural History 515 



chief factor of evolution, both directly, by securing the 

 well-being of the species while diminishing the waste 

 of energy, and indirectly, by favouring the growth of in- 

 telligence. 



Mutual help is practised extensively among insects of 

 various kinds. The Burying Beetles, which usually lead a solitary 

 life, call to their aid a number of their fellows when there is a 

 corpse to be buried. Many caterpillars weave a silken web to 

 make a shelter for a whole brood, while the full-grown Procession 

 Caterpillars march together from their feeding-ground on the 

 trees to a soft place on the ground where they can bury them- 

 selves and become moths. Locusts display gregarious habits also 

 which are of mutual advantage; for instance, it is a common 

 practice for the wingless young to make a living bridge over a 

 moderately broad stream, plunging into the water and grappling 

 for sticks and straws, and scrambling for a breathing space on 

 their comrades' bodies, till the whole swarm passes across the 

 stream. Comparatively few are drowned, as the same individuals 

 are seldom in the water the whole time. Such associations for 

 mutual aid suggest the beginnings of societies, but they are not 

 nearly so highly evolved as those seen among the termites, ants, 

 bees, and wasps, where the social habits extend to the welfare 

 of the young, and co-operation reaches a high level. Kropotkin 

 says, "If we knew no other facts from animal life than what 

 we know about the ants and the termites, we already might safely 

 conclude that mutual aid (which leads to mutual confidence, the 

 first condition of courage) and individual initiative (the first 

 condition for intellectual progress) are two factors infinitely 

 more important than mutual struggle in the evolution of the 

 animal kingdom." The fact is that in the struggle for exist- 

 ence, which includes all the answers-back that living creatures 

 make to environing difficulties and limitations, sociality 

 pays just as well as intensified competition, or, it may be, pays 

 better. 



