Woman's reproductive organs are far older than man's and far more highly evolved. Even in the lowest mammals, as well as in woman, the ovaries, uterus, vagina, etc., are similar, indicating that the female reproductive system was one of the first things perfected by nature. On the other hand, the male reproductive organs, the testicles and the penis, vary as much among species and through the course of evolution as does the shape of the foot — from hoof to paw. Apparently, then, the male penis evolved to suit the vagina, not the vagina to suit the penis.

The First Sex, ch. 1 - Woman and the Second Sex (1971).