You're welcome.

Huh, I guess I was paying less attention to the book review than I thought (I had it in the background while playing vidya)

Wiki for Sex & Culture (1935) by JD Unwin

Didn't realize the book was that old. Still very prophetic 90 years later.

Unwin seems to be a Brit, an Oxford Scholar & a WWI vet.

He died at 40 the year after the book was published from complications from a medical procedure.

By 'civilized' societies the book refers specifically to the following sixteen historical peoples:  Sumerians, Babylonians, Egyptians, Assyrians, Hellenes, Persians, Hindus, Chinese, Japanese, Sassanids, Arabs (Moors), Romans, Teutons, and Anglo-Saxons.

In Sex and Culture (1934), Unwin studied 80 primitive tribes and six known civilizations through 5,000 years of history. He claimed there was a positive correlation between the cultural achievement of a people and the sexual restraint they observe. Aldous Huxley described Sex and Culture as "a work of the highest importance" in his literature.

According to Unwin, after a nation becomes prosperous, it becomes increasingly liberal concerning sexual morality. It thus loses its cohesion, impetus, and purpose, which he claims is irrevocable.

Unwin also stated, "In the past, too, the greatest energy has been displayed only by those societies which have reduced their sexual opportunity to a minimum by the adoption of absolute monogamy [...]. In every case the women and children were reduced to the level of legal nonentities, sometimes also to the level of chattels, always to the level of mere appendages of the male estate. Eventually they were freed from their disadvantages, but at the same time the sexual opportunity of the society was extended. Sexual desires could then be satisfied in a direct or perverted manner [...]. So the energy of the society decreased, and then disappeared." He further notes, "No society has yet succeeded in regulating the relations between the sexes in such a way as to enable sexual opportunity to remain at a minimum for an extended period." And thus, all societies have collapsed. His hope for the future is that, "by placing the sexes on a level of complete legal equality, and then by altering its economic and social organization in such a way as to render it both possible and tolerable for sexual opportunity to remain at a minimum for an extended period," a society may flourish.