EUGENICS AND WAR 421 



sifts, i. e., eliminates discriminatively, includes mi (a more than in- 

 ternecine competition between fellows of the same kith and kin. As 

 Darwin said, the phrase is to be used " in a large and metaphorical sense, 

 including dependence of one being on another, and including (which 

 is more important) not only the life of the individual, but success in 

 leaving progeny." It may be that the struggle is most severe between 

 members of the same or nearly related species, though Darwin did not 

 give many examples of this, but, in any case, we must not generalize 

 the story of the black and brown rat into a theory of life. The struggle 

 for existence is often manifested in an endeavor after well-being. It 

 is the clash that occurs whenever organisms do in any way assert them- 

 selves against limitations and difficulties. The answers-back may be 

 competitive or non-competitive, self-regarding or other-regarding, with 

 teeth and claws, or with wits and kindness. In face of overwhelming 

 difficulties and thwarting limitations, one creature sharpens its weapons, 

 another thickens its armor, a third gives its offspring a better send-off 

 on the journey of life, and a fourth makes some experiment in state- 

 socialism. The modes of reaction are many, and one never to be for- 

 gotten is that evasive change of habit and habitat which we call 

 parasitism — the door to which is always open. The struggle for exis- 

 tence includes all the endeavors of mate for mate, of parent for off- 

 spring, of kin for kin, as well as every degree of self-assertiveness from 

 the young cuckoo ousting the rightful tenant of the nest to the canni- 

 balism in the cradle that occurs in the egg-capsules of the whelk. 



It is said, however, that in the long run what counts is that some 

 members of a varying species are fitter for the conditions of life than 

 their neighbors, and therefore survive. This is true, but the eliminat- 

 ing clash is not necessarily between the individuals, the pruning shears 

 are often in the hands of the environment. The survivor in a plague- 

 stricken family does not survive at the expense of his kin, nor compete 

 with his kin ; his phagocytes parry the microbe. In lining its nest with 

 two thousand feathers the long-tailed tit unmistakably strengthens its 

 own and its family's foothold in the struggle for existence, but its 

 reaction to environing difficulties does not hurt any other tit. 



Two other points should be noted. The mode of the struggle for 

 existence is not always competitive, and the result of the struggle for 

 existence is not always the discriminate elimination of the relatively less 

 fit to the conditions. Sometimes all that we can discern is a thinning 

 — not a sifting — and that does not in itself make for evolution. The 

 only result of the struggle for existence that necessarily makes for evo- 

 lution — progressive or retrogressive — is discriminate selection, where 

 the survivors survive in virtue of the possession of a particular character 

 — which may be better weapons, stronger armor, swifter feet, greater 



