*Both monkeys and chimps interact differently with a person who is unable to give them food, versus one who is able but unwilling; they don’t want to be around the latter: “What a mean hairless primate—they could have given me food but chose not to.” Particularly interesting work, by psychologist Laurie Santos of Yale, has shown that other primates have their own sense of agency. A human test subject rates their preferences for an array of household items. Find two that are rated equivalently, and force the person to choose one over the other; thereafter, they show a preference for that item: “Hmm, I’m a rational agent of free will, and if I chose this one over that one, it must have been for a good reason.” Do the same thing with capuchin monkeys—force them to choose one of two different colored M&M’s, have them believe that they made a choice (even under circumstances where, unknown to them, their choice is actually forced)—and they show a preference for that color thereafter. If a human chooses for them, no preference emerges.