The Mysterious Case of Primate Peacefulness

How do bonobos stay so relaxed in a Darwinian world?

In these dark days of seemingly perpetual war, mass shootings and online aggression, it's ever more important to try to understand how and why peace can conquer violence.

A sudden shift in the course of the Congo river sometime between one and three million years ago split a population of primates that had only recently differentiated from our ancestors. Over the ensuing centuries, they evolved in two very different directions. Those on the north side of the river became chimpanzees, while those on the south side became bonobos. These two creatures look very similar, and share almost all their DNA, but their behavior and "culture" differ dramatically.

Each of these species has been studied for decades, both in the wild and in captivity. Over the years, chimpanzee violence has been well-documented by Jane Goodall and others: group violence against neighboring troops (“war”), rape, infanticide, murder. But in all these years of observation, not a single instance of a bonobo killing another bonobo has been observed. Not in the wild. Not in captivity.

Primatologist Frans de Waal summed up their fundamental differences succinctly: “Chimps use violence to get sex, while bonobos use sex to avoid violence.”

But how can this be? How can two species so similar even primatologists struggle to tell them apart be so different in terms of how they deal with their own aggressive impulses?