This section is from the book "Human Sexuality", by J. Richardson Parke. Also available from Amazon: Human Sexuality.
At a very early period society made a discovery upon which was founded one of the most universal of our moral laws, and one which, I think I am safe in stating, has been the least frequently infringed. Tribes made war upon neighboring tribes not only for enlargement of territory, and to avenge injuries, but to secure wives. A bachelor was compelled to catch a wife, either by force or strategy, not only for his own benefit, but because the health of the community and that of posterity demanded it. He accordingly prowled around a village or hunting ground of the enemy until an eligible candidate for his love (!) came out to fill her pitcher, or gather fuel, when he sprang gallantly upon her, knocked her down with his club, and dragged her off in triumph.
The process of courtship was simple but radical; presenting, in some respects, advantages not possessed by the modern method, A man with a hare-lip, bow-legs, or an impediment in his speech, provided he had a true aim and a strong arm, had an equal chance with the best of them, and at the same time the question of domestic sovereignty was pretty well settled at the very outset.
The psychology of such a wooing is readily explained. It had been observed that alien wives produced more children and stronger children than the native articles, the discovery recently alluded to; and also that puny, weak and infrequent offspring were the product of blood relationship between husband and wife; therefore they decreed against marriages of consanguinity. These ordinances relating to marriage, enacted by the wise graybeards of the tribes, and frequently put forth as commandments of the gods, were at first obeyed by the young through fear, and afterwards through a mentally ingrained tribal tradition.
 
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sexuality, reporduction, genitals, love, female, humans, passion