I don't disagree with any of those points. My original post just stated that I couldn't imagine any fitness pressure that would be making humans smarter and, if

I don't disagree with any of those points. My original post just stated that I couldn't imagine any fitness pressure that would be making humans smarter and, if anything, we were probably going in the other direction. My secondary point was that change can happen on short timelines. I do want to mention that larger social organizations were quite widespread in the Americas, despite the existence of hunter-gatherer tribes. The new world certainly wasn't an uncivilized wasteland when Europeans arrived. Epigenetic factors can be triggered buy group size (domestication) as well. So those hunter-gatherer tribes might share the same genetic traits but express them differently based on their environment.