Over on the monthly meetup, someone mentioned that he had found someone with a
RationalWiki entry pushing a theory that western Europeans were bred for individuality by Catholic marriage laws. Unfortunately, this comes from an actual paper by Joseph Henrich in
Science (sigh), if you see history archaeology or linguistics in Nature or Science be prepared for disappointment)
https://www.science.org/doi/10.1126/science.aau5141 summarized
hereI think most of the criticism was on corporate social media where its hard to find again or may be deleted or hidden (double sigh) but it included things like "nobody in western Europe in the early Middle Ages had the power to control marriage across a wide area" and "the British upper class had a lot of cousin marriages in the 18th and 19th century." And many people are highly motivated to reason why Catholic and Protestant Europeans were forordained to dominate the world. I don't know of anyone who has looked into the authors or their footnotes.
Even in the second half of the Middle Ages, the western Church struggled to enforce the rule against clerics marrying. When it stopped them from marrying in a church, it found a lot of clerks with friendly housemaids and neighbours-with-benefits.
So at first glance it seems like a thing which could have happened, but when you look at the history of similar theories and who gets excited by them, you realize you should be very careful. Eg. the pioneering sociologist Max Weber decided that north-west Europe was rich in 1910 because Protestantism, then France and southern Germany got rich too, then Japan and South Korea, and the idea that
the Protestant Ethic is the Spirit of Capitalism got hard to swallow.
Edit: its also worth saying that the authors and the people willing to speak kindly about this project come from disciplines such as business, economics, psychology, anthropology, human evolutionary biology (a whole department at Harvard!)
The ancient Greeks and Romans were very strong on monogamy: whoever people got naked with, they could have one and only one spouse at a time, and if powerful men such as kings tried to marry more than one person at a time that was a mark of the barbarian. AFAIK the Egyptians, Assyrians, and Babylonians were basically monogamous too.