The Compassionate Instinct

Second, when ancestral humans were harmed by others, the propensity for revenge may have helped them deter the aggressors from harming them again. In highly mobile modern societies such as ours, often we can simply end relationships in which we’ve been betrayed. But in the close societies in which our earliest hominid ancestors lived, moving away usually wasn’t a good option. In fact, ostracism from the group was often a severe punishment that carried the risk of death. Therefore, our ancestors often had to find more direct ways to cope with the despots and bullies in their midst. One way to cope with someone who has taken advantage of you is to make it less profitable for that person to do so again.

This punishment function of revenge is quite prevalent in many animal societies. For example, if a rhesus macaque monkey finds a source of a highly valued food but doesn’t issue one of the “food calls” used to alert others to the big discovery, the animal is likely to be attacked when others realize what he’s done. In a scenario like this, you can almost see the evolutionary logic at work: If you don’t want to share your food with us, then we’re going to make it less profitable for you to try and be sneaky about it. In this way, revenge may have evolved because of its ability to teach our aggressors that crime doesn’t pay.

Finally, revenge may have been useful for punishing (and reforming) “free riders,” people who enjoy the benefits of a group’s efforts without contributing to those efforts. To spur humans’ prodigious tendencies for cooperation, our ancestors had to ensure that when free riders failed to “pitch in” and make appropriate contributions to the common good, they suffered dire consequences.

With these adaptive functions in mind, it gets easier to accept the idea that revenge is a built-in feature of human nature, despite its dreadful effects in the world today. We might rightly view revenge as a modern-day problem, but from an evolutionary point of view, it’s also an age-old solution.

TRUTH #2: THE CAPACITY FOR FORGIVENESS IS A BUILT-IN FEATURE OF HUMAN NATURE

So revenge is an authentic, standard-issue, bred-in-the-bone feature of human nature. But that doesn’t imply that forgiveness is a thin veneer of civility, slapped on top of a brutish, vengeful core. Nothing could be further from the truth. In fact, when you use the conceptual tools of evolutionary science, you can’t help but conclude that our capacity for forgiveness is every bit as authentic as our capacity for revenge.

For example, there’s evidence that forgiveness is just as universal among humans as revenge is. Although Martin Daly and Margo Wilson found that blood revenge has emerged as an important social phenomenon in 95 percent of the societies they examined, my own analysis revealed that the concepts of forgiveness, reconciliation, or both have been documented in 93 percent of those same societies.

Is it possible that forgiveness and reconciliation really didn’t exist among that remaining 7 percent? The evolutionary biologist David Sloan Wilson has observed that “it is actually difficult to find descriptions of forgiveness in hunter-gatherer societies, not because forgiveness is absent but because it happens so naturally that it often goes unnoticed.” I think Wilson may be correct, and not just about hunter-gatherers but about all societies. Forgiveness and reconciliation may be so common and so taken for granted by anthropologists as to be regarded, quite literally, as nothing to write home about.

And just as with revenge, research has found that forgiveness is also widespread across the animal kingdom, offering further evidence of its evolutionary significance. More than two decades ago, primatologist Frans de Waal and a colleague published results showing that friendly behaviors such as kissing, submissive vocal sounds, touching, and embracing were actually quite common after chimpanzees’ aggressive conflicts. In fact, these were the chimpanzees’ typical responses to aggressive conflicts. The researchers observed 350 aggressive encounters and found that only 50, or 14 percent, of those encounters were preceded by some sort of friendly contact. However, 179, or 51 percent, of the aggressive encounters were followed by friendly contact. This was a staggering discovery: friendly contact was even more common after conflict than it was during conflict-free periods. Chimps kiss and make up in the same way people do.