Sex differentiation and sexual selection exist almost universally throughout the animal and vegetable kingdoms, everywhere save in the lowest forms of being. They take strange and startling forms, and like everything else in nature manifest amazing ingenuity. People who wish to prove this or that about human sex relations will advance arguments from nature; but as a matter of fact we can learn nothing whatever from nature, except her determination to preserve the products of her activity and to keep them up to standard. Sometimes nature will give the precedence in power, speed and beauty to the male, and sometimes to the female. She is perfectly ruthless, and willing in the accomplishment of her purpose to destroy the individuals of either sex. She will content the most rabid feminist by causing the female spider to devour her mate when his purpose has been accomplished; or by causing the male bee to fall from his mating in the air, a disemboweled shell. As for man, he has won his supremacy over nature by his greater power to combine in groups; by his more intense gregarious, or herd instincts, which enabled him to fight and destroy creatures which would have exterminated him if he had fought them alone. So in primitive society everywhere, we find that the individual is subordinated to the group, and the "folkways" give but little heed to personal rights. Very thorough investigations have been made into the life of primitive man in many parts of the world, and the anthropologists are now arguing over the exact meaning of the data. We shall not here attempt to decide among them, but rest content with the statement that communism and tribal ownership is a widespread social form among primitive man, so much so as to suggest that it is an early stage in social evolution.