>>17939944 (OP)
19th Century Race Realists believed the Saharan Desert was a "Great Filter" where only the most clairvoyant and intelligent among early humans could pass through successfully, and this is why blacks, the ones that remained in Africa, are "less evolved" than everyone else that left Africa
There are several issues with this theory
1.) Humans didn't leave Africa in one giant wave but in multiple waves over the course of tens of thousands of years, and humans even travelled back into Africa on multiple occasions
2,) The Sahara was not a desert before 8,000 years ago, so this debunks the "great filter" model, and 8,000 years is not recent enough for significant evolutionary divergence to happen anyways, even 50,000 years may not be recent enough. For context, evidence suggests early humans emerged from species of archaic humans starting from around 250,000 years ago, well before modern humans began migrating out of Africa to begin with. So from the context of our more modern understanding of human migration and evolution, then there are plenty of arguments against 19th century Race Realism.
