We all know monkey see, monkey do. And Sam the squirrel monkey sees and does more than most. For one thing, he eats a wider range of food. He likes green vegetables—spinach and kale. True story: He ...

In the video, a preposterously cute, gray squirrel monkey named Dalton bonks his head against a computer screen in front of him. Wide-eyed and muttonchopped, Dalton has quite the setup—the screen, ...