We humans may share around 98% of our DNA with chimpanzees and other simians, but we're still pretty different. After all, we have smart phones, and monkeys have--well--they don't have smart phones.

But in often surprising ways, people and monkeys are quite similar. For example, say you're waiting in line at a buffet, mouth watering at the prospect of sampling some tasty‑looking bar‑b‑q chicken. But just before it's your turn, the guy in front of you grabs the last several pieces, piling his plate high with way more chicken than any one person could reasonably eat.

You're be angry, right? And probably stung by the unfairness and selfishness of the greedy chicken grabber. You might even confront the guy with a few reprimanding words.

Now, we might assume that things like fairness and the desire to punish or correct those who violate social norms are peculiar to our highly evolved human minds. But guess what: some monkeys, too, will punish those they perceive to have gotten more than their fair share. Some research has found that chimps in captivity will punish a fellow chimp who has stolen food by pulling a rope to collapse the table holding the food.

Meanwhile, researchers at Yale and Harvard have observed how Capuchin monkeys will knock down the table of another monkey they perceive as simply having too much food, even if they didn't steal it. Almost as though the monkeys are capable of acting spitefully.

So although we tend not to express disapproval by knocking people's food to the floor, our feelings of unfairness and spite appear to have pretty deep evolutionary roots.