Now, bear with me here. Neandertals were stupid, right? So why would one of their brain genes be advantageous in modern humans?
There are so many possibilities here. 1. Late Neandertals certainly weren’t stupid. Consider the Châtelperronian. And the European Mousterian includes basically all the elements that are thought to represent cognitive sophistication in MSA Africans. 2. Neandertal brains were big, and their heat generation requirements means that energetic constraints were very different from other archaic populations. The brain doesn’t function in isolation — its development, growth, and ongoing maintenance depend on metabolic constraints. So Neandertals might easily have had brain development alleles that had different responses to their high-energy lifestyles. Considering that early Upper Paleolithic people had much more effective foraging strategies than Neandertals, high-energy brain development may have had an even greater advantage than it had previously enjoyed. 3. Modern humans are variable in brain morphology and cognition.
