Richard Wrangham: Violence, Sex, and Fire in Human Evolution | Lex Fridman Podcast #229

The following is a conversation with Richard Wrangham, a biological anthropologist at Harvard specializing in the study of primates and the evolution of violence, sex, cooking, culture, and other aspects of ape and human behavior at the individual and societal level. He began his career over four decades ago working with Jane Goodall in studying the behavior of chimps, and since then, has done a lot of seminal work on human evolution and has proposed several theories for the roles of fire and violence in the evolution of us hairless apes, otherwise known as Homo sapiens. This is the Lex Fridman Podcast. To support it, please check out our sponsors in the description. And now, here's my conversation with Richard Wrangham. You've said that we are much less violent than our close living relatives, the chimps. Can you elaborate on this point of, uh, how violent we are and how violent our evolutionary relatives are?

Well, I haven't said exactly that we're less violent than chimps. What I've said is that there are two kinds of violence. One stems from proactive aggression, and the other stems from reactive aggression.

Mm-hmm.

Proactive aggression is planned aggression. Reactive aggression is impulsive, defensive. It's reactive because, uh, it takes place in seconds after the threat. And the thing that is really striking about humans compared to our close relatives is the great reduction in the degree of, of reactive aggression. So we are far less violent than chimps, uh, when prompted by some relatively minor threat within our own society. And the way I judge that is, um, with not super satisfactory data, but, uh, the, uh, the study which is particularly striking is one of, uh, people living as, um, hunter-gatherers in a really, um, upsetting kind of environment, namely, um, people in Australia, uh, living in, uh, a place where they've got a lot of alcohol abuse, uh, there's a lot of domestic violence. Uh, it's all, uh, a sort of a, a, a society that is, um, you know, as bad from the point of view of violence as, uh, an ordinary society can get. Uh, there's excellent data on the frequency with which people actually have physical violence and hit each other, and we can compare that to, uh, data from several different sites comparing, uh, we're looking at chimpanzee and bonobo violence.

Mm-hmm.

And the, uh, difference is, uh, between two and three orders of magnitude. The frequency with which chimps and bonobos hit each other, chase each other, charge each other, uh, physically engage is, uh, somewhere between 500 and 1,000 times, uh, higher than in humans.

Mm-hmm.

So there's something just amazing about us. And, you know, this has been recognized for, for centuries. Uh, Aristotle drew attention to the fact that we behave in many ways like domesticated animals because we're so un-violent. But, you know, people say, "Well, what about, you know, the hideous engagements of the 20th century, the first and second World War and, and, and much else besides?" And, uh, that is all proactive violence. You know, all of that is, is gangs of people, um, making deliberate decisions to go off and attack in circumstances which ideally, uh, the attackers are going to be able to make their kills and then get out of there. Uh, in other words, not, uh, face confrontation. That's the ordinary way that armies try and work. And, um, and there, it turns out that, uh, humans and chimpanzees are in a very similar kind of state. That is to say if you look at the, the rate of death from chimpanzees conducting proactive coalitionary violence, uh, it's, uh, very similar in many ways to what you see in humans. So we're not down-regulated with proactive violence. It's just this reactive violence that is strikingly reduced in humans.