The modification of selection by war is far more manifold than the literature on the biological effects of war would lead the reader to suppose. All wars are partly eugenic and partly dysgenic; some are mainly the one, some are mainly the other. The racial effects of war occur in at least three periods:
- The period of preparation.
- The period of actual fighting.
- The period of readjustment after the war.
The first division involves the effect of a standing army, which withdraws men during a part of the reproductive period and keeps most of them in a celibate career. The officers marry late if at all and show a very low birth-rate. The prolonged celibacy has in many armies led to a higher incidence of venereal diseases which prolongs the celibacy and lowers the birthrate.38 Without extended discussion, the following considerations may be named as among those which should govern a