Without going to the somewhat obscure analogies of biological science, it is evident from the simple facts of the world that, if at any stage of human development warfare ever did make for the survival of the fit, we have long since passed out of that stage. When we conquer a nation in these days, we do not exterminate it: we leave it where it was. When we "overcome" the servile races, far from eliminating them, we give them added chances of life by introducing order, etc., so that the lower human quality tends to be perpetuated by conquest by the higher. If ever it happens that the Asiatic races challenge the white in the industrial or military field, it will be in large part thanks to the work of race conservation, which has been the result of England's conquest in India, Egypt, and Asia generally, and her action in China when she imposed commerical contact on the Chinese by virtue of military power. War between people of roughly equal development makes also for the survival of the unfit, since we no longer exterminate and massacre a conquered race, but only their best elements (those carrying on the war), and because the conqueror uses up his best elements in the process, so that the less fit of both sides are left to perpetuate the species.
Nor do the facts of the modern world lend any support to the theory that preparation for war under modern conditions tends to preserve virility, since those conditions involve an artificial barrack life, a highly mechanical training favorable to the destruction of initiative, and a mechanical uniformity and centralization tending to crush individuality, and to hasten the drift towards a centralized bureaucracy, already too great.