From https://www.bbc.com/earth/story/20160912-a-soviet-scientist-created-the-only-tame-foxes-in-the-world
This suggests that human evolution selected for cooperation, tolerance and gentleness – and not, necessarily, for intelligence.
“We always assume that intelligence is responsible for our success,” says Hare. “That humans became smarter, which… allowed us to invent wheels and agriculture and iPhones. But what if that wasn’t what happened?”
Hare suspects that, “like the foxes, and like dogs, we became friendlier first, and then got smarter by accident. This would mean that our prosocial skills, the skills that allow for cooperation and friendliness, were what made us successful.”