82:5.1

Very early the savage observed that race mixture improved the quality of the offspring. It was not that inbreeding was always bad, but that outbreeding was always comparatively better; therefore the mores tended to crystallize in restriction of sex relations among near relatives. It was recognized that outbreeding greatly increased the selective opportunity for evolutionary variation and advancement. The outbred individuals were more versatile and had greater ability to survive in a hostile world; the inbreeders, together with their mores, gradually disappeared. This was all a slow development; the savage did not consciously reason about such problems. But the later and advancing peoples did, and they also made the observation that general weakness sometimes resulted from excessive inbreeding.