Here is a different theory: The Lost Sex Study - Christianity Today magazine - ChristianityTodayLibrary.com
Seeking to test the Freudian notion that civilization is a byproduct of repressed sexuality, the scholar J. D. Unwin studied 86 different societies. His findings startled many scholars - above all, Unwin himself - because all 86 demonstrated a direct tie between monogamy and the "expansive energy" of civilization....
For Roman, Greek, Sumerian, Moorish, Babylonian, and Anglo-Saxon civilizations, Unwin had several hundred years of history to draw on. He found with no exceptions that these societies flourished during eras that valued sexual fidelity. Inevitably, sexual mores would loosen and the societies would subsequently decline, only to rise again when they returned to more rigid sexual standards.
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