Sexual Dimorphism

Abstract

THE theory of sexual selection never pretended to explain unisexual inheritance. Its author started with a fact:—“Inasmuch as peculiarities often appear under domestication in one sex and become hereditarily attached to that sex, so no doubt it will be under nature” (“Origin of Species,” 6th ed. p. 69).¹ Neither does the theory of natural selection pretend to explain ordinary, i.e. bisexual, inheritance. But Mr. Cunningham pretends that his theory does explain unisexual inheritance, and having in spite of the statement contained in the concluding sentence of the above letter—given very full consideration to his views, I have come to the opposite conclusion. I repeat that his theory does not explain unisexual inheritance.