Yet we should remember that brain evolution was just one part of our ascent as a species. For all our neocortical power, human science and art wouldn’t be possible without one other key innovation: our thumbs.[65] Animals with comparable or even larger (in absolute terms) neocortices than humans—such as whales, dolphins, and elephants—don’t have anything like an opposable thumb that can precisely grasp natural materials and fashion them into technology.
