Physicist Chris Adami, Ph.D., would like you to imagine the zombie apocalypse. Zombies can only feed off the brains of the living, right? So, “if everyone was turned into a zombie, then zombies would have a very hard time surviving.” Naturally. Well, the same goes for mean and selfish people.Adami and Arend Hintze, from Michigan State University’s Beacon Center for the Study of Evolution in Action, aren’t actually preparing for the (inevitable) takeover of the living dead, but the analogy works to illustrate why being a selfish person isn’t a good bet in the long run. In their August 2013 paper in Nature Communications, Adami and Hintze use complex mathematical models of game theory to show that nice guys shall inherit the Earth.“In a sentence, the general idea is that being mean doesn’t pay, because you reap what you sow,” says Adami.At the most basic level, there are numerous strategies that a person can employ when faced with a problem—in this case, the classic Prisoner’s Dilemma, used in all manner of scientific, economic and political study: Isolated from one another, two suspects of a crime must decide whether to confess or plea the Fifth, thereby sealing their own—and each other’s—fates. One type of strategy used to guide that decision, called “zero-determinant” is, in effect, a selfish and coercive tactic. A ZD strategist tries to maximize her own payoff to the detriment of those employing more cooperative sucker strategies. She forces her opponent to accept a smaller reward while she gets the most she can wrangle out of the deal.This may work for a while, giving ZD the upper hand over and over again, but on an evolutionary timeline, it’s untenable. Why? Because ZD only works against non-ZD, so if everyone on Earth were a ZD (remember the zombies?), the only way to survive would be to adapt a kinder, plays-well-with-others approach.“In the short term, mean, coercive strategies can absolutely have an advantage,” Adami explains. “We have to keep in mind that we are talking here about a come-uppance that takes many generations to materialize.” So, that conniving you know what at work might get that promotion you were gunning for, but evolution’s got your back.