“The concerned scientist leaned in close, shot a glance toward Honnold, and said, ‘That kid’s amygdala isn’t firing.'” How can some people regularly take risks that are almost too scary for the rest of us to experience, even on video from the safety of our living rooms? To try to answer that question, researchers studied free climber Alex Honnold. “On the hardest parts of some climbing routes, his fingers will have no more contact with the rock than most people have with the touchscreens of their phones, while his toes press down on edges as thin as sticks of gum.” From J.B. Mackinnon in Nautilus: The Strange Brain of the World’s Greatest Solo Climber.