Charles Darwin by Grant Allen — Read

In the same volumes with the 'Descent of Man' Darwin included his admirable treatise on sexual selection. This form of selection he had already dealt with briefly in the 'Origin of Species; ' but as in his opinion it was largely instrumental in producing the minor differences which separate one race of men from another, he found it necessary to enlarge and expand it in connection with his account of the rise and progress of the human species.

Among many animals, and especially in the higher classes of animals, the males and females do not mate together casually; there is a certain amount of selection or of courtship. In some cases, as with deer and antelopes, the males fight with one another for the possession of the females. In other cases, as with the peacock and the humming-birds, the males display their beauty and their skill before the eyes of the assembled females. In the first instance, the victor obtains the mates; in the second instance, the mates themselves select from the group the handsomest and most personally pleasing competitor. Sexual selection, of which these are special cases, depends on the advantage possessed by certain individuals over others of the same sex and species solely in respect to the question of mating.