2. The amount of Andite stock in any people. Among such groups sex has become expressive of both the highest and the lowest in both the physical and emotional natures.

The Sangik races had normal animal passion, but they displayed little imagination or appreciation of the beauty and physical attractiveness of the opposite sex. What is called sex appeal is virtually absent even in present-day primitive races; these unmixed peoples have a definite mating instinct but insufficient sex attraction to create serious problems requiring social control.

The mating instinct is one of the dominant physical driving forces of human beings; it is the one emotion which, in the guise of individual gratification, effectively tricks selfish man into putting race welfare and perpetuation high above individual ease and personal freedom from responsibility.

As an institution, marriage, from its early beginnings down to modern times, pictures the social evolution of the biologic propensity for self-perpetuation. The perpetuation of the evolving human species is made certain by the presence of this racial mating impulse, an urge which is loosely called sex attraction. This great biologic urge becomes the impulse hub for all sorts of associated instincts, emotions, and usages—physical, intellectual, moral, and social.

With the savage, the food supply was the impelling motivation, but when civilization insures plentiful food, the sex urge many times becomes a dominant impulse and therefore ever stands in need of social regulation. In animals, instinctive periodicity checks the mating propensity, but since man is so largely a self-controlled being, sex desire is not altogether periodic; therefore does it become necessary for society to impose self-control upon the individual.

No human emotion or impulse, when unbridled and overindulged, can produce so much harm and sorrow as this powerful sex urge. Intelligent submission of this impulse to the regulations of society is the supreme test of the actuality of any civilization. Self-control, more and more self-control, is the ever-increasing demand of advancing mankind. Secrecy, insincerity, and hypocrisy may obscure sex problems, but they do not provide solutions, nor do they advance ethics.

The story of the evolution of marriage is simply the history of sex control through the pressure of social, religious, and civil restrictions. Nature hardly recognizes individuals; it takes no cognizance of so-called morals; it is only and exclusively interested in the reproduction of the species. Nature compellingly insists on reproduction but indifferently leaves the consequential problems to be solved by society, thus creating an ever-present and major problem for evolutionary mankind. This social conflict consists in the unending war between basic instincts and evolving ethics.

Among the early races there was little or no regulation of the relations of the sexes. Because of this sex license, no prostitution existed. Today, the Pygmies and other backward groups have no marriage institution; a study of these peoples reveals the simple mating customs followed by primitive races. But all ancient peoples should always be studied and judged in the light of the moral standards of the mores of their own times.