> during which the hot-weather civilizations did stuff like invent algebra
When algebra was invented the Fertile Crescent was significantly wetter and cooler than it is now.
When algebra was invented the Fertile Crescent was significantly wetter and cooler than it is now.
The claim is that severe winter conditions select for intelligence, not that intelligence grades continuously with average temperature!
That 1500 BC Babylon was neither a cold-weather clime nor an arid clime is evidence against the cold winter hypothesis.
(To your point about intelligence vs. progress, it's suggestive evidence, not dispositive evidence, but the amount of suggestive evidence over the course of human history makes the cold winter hypothesis pretty funny.)