The surprising answer: a lot. Feminist historian Mary Beard, of course, says it's because of male chauvinism [How often do you think about the Roman Empire? Expert has thoughts on the new TikTok trend, SkyNews, September 27, 2023]. Well, here's one reason to think about it: I believe the rise and fall of Rome coincided with the rise and fall of Roman intelligence. Rome fell because its people were becoming less intelligent. And the same thing is happening today.

Many theories attempt to explain the Roman Empire's collapse. It was overstretched, meaning it could no longer efficiently transport the necessary raw materials. Or it came up against problems that its elite could not solve, leading to the populace losing faith in these elites. The problem with these explanations is that they invite obvious questions. Why did Rome gradually become less efficient? Why were its elites decreasingly able to solve the problems of running a large empire?

The essence of intelligence is "solving problems." Group-level intelligence is associated with all of the markers of civilization: wealth, numeracy, education, democracy, social trust, obedience to the law and just authority, and, importantly, good health and public hygiene achieved with plumbing and sanitation. (This is explored in the book Intelligence: A Unifying Construct for the Social Sciences, by the late Richard Lynn and Tatu Vanhanen.)

We would then expect civilization to weaken selection for intelligence because it reduces environmental harshness and leads to improved living conditions: again, good public health and hygiene because of widely available food, clean water, and medical care, etc., which decreases the relationship between wealth (socioeconomic status is a robust correlate of intelligence) and how many surviving children one has, with such a relationship existing in the earlier stages of civilization. (I discussed this in my book At Our Wits' End, with my co-author Michael Woodley of Menie.)