Frans de Waal calls his book Mama’s Last Hug in reference to an emotional encounter between Mama, a 58-year-old chimpanzee, and Jan van Hooff, an 80-year-old biology professor. Mama is frail and near death when Van Hooff, who had overseen her care for decades, enters her cage at Burgers Zoo in the Netherlands. Mama smiles and Van Hooff bends toward her. She strokes his white hair and drapes one of her arms around his neck, patting the back of his head with her long fingers. “This was typical Mama,” writes De Waal, who had long observed the chimpanzee. De Waal gave her the name Mama because of her matriarchal position. “She had the air of a grandmother who had seen it all and didn’t take nonsense from anybody,” De Waal writes. “I had never sensed such wisdom and poise in any other species but my own.” When Van Hooff entered Mama’s cage, “she must have sensed Jan’s trepidation about invading her domain, and she was letting him know not to worry. She was happy to see him.”
The touching scene between Mama and Van Hooff has been viewed over 10 million times on YouTube. Clearly it has struck a deep emotional chord in people, no doubt because of the joy and tenderness that the chimpanzee displays at the end of her long life. De Waal, who runs Living Links Center at the Yerkes National Primate Research Center in Atlanta, uses the scene to open his investigation into the emotions of animals, from primates to dogs to rats. “Let me start off with a radical proposal: emotions are like organs,” he writes. “They are all needed, and we share them with all with other mammals.” Those who are familiar with De Waal’s research know the proposal is not so radical, as the primatologist has for decades been showing humans that we are not as special as many of our species seem to think we are. The title of his previous book offers a keen summary of his outlook:
Are We Smart Enough to Know How Smart Animals Are?
De Waal’s body of work adds up to a sustained argument against human exceptionalism. His 2013 book, The Bonobo and the Atheist , takes aim at critics and dissenters—anthropologists, behaviorists, Christian fundamentalists—and at the “strident atheism” of Richard Dawkins and Christopher Hitchens. De Waal, a non-believer himself, sees religion as an offshoot of our biological drive to do good. The interview below was conducted on the heels of the release of The Bonobo and the Atheist . De Waal was an amiable conversationalist with a sly sense of humor. He was a fast talker, bursting with ideas, displaying the self-assurance of a prominent scientist who’s fought his share of intellectual battles.
Most people assume that humans are fundamentally different from the rest of the animal world. What do you think?
Many people believe that. But to biologists we are animals. It’s hard to believe we are fundamentally different because there is no part of the human brain that is not present in a monkey’s brain. Our brains are bigger and we certainly have a more powerful computer than any other animal, but the computer is not fundamentally different.
So there’s no fundamental divide between humans and chimpanzees?
No. If you were to ask what the big difference is, I would say it’s probably language. But like all capacities, once you break them down into pieces, you are going to find some of these parts in other species.
There is no part of the human brain that is not present in a monkey’s brain.
Why are so many people wedded to the idea that humans are special?
We’re raised with those ideas. It’s an old Christian idea that humans have souls and animals don’t. I sometimes think it’s because our religions arose in a desert environment in which there were no primates, so you have people who lived with camels, goats, snakes, and scorpions. Of course, you then conclude that we are totally different from the rest of the animal kingdom because we don’t have primates with whom to compare ourselves. When the first great apes arrived in Western Europe—to the zoos in London and Paris—people were absolutely flabbergasted. Queen Victoria even expressed her disgust at seeing these animals. Why would an ape be disgusting unless you feel a threat from it? You would never call a giraffe disgusting, but she was disgusted by chimpanzees and orangutans because people had no concept that there could be animals so similar to us in every possible way. We come from a religion that’s not used to that kind of comparison.
Yet a lot of the scientists who make the case for human exceptionalism are not religious. They still believe that humans are fundamentally different.
Of course, they are not biologists. The social sciences and the humanities are still very influenced by religion. They have this whole mindset that humans are absolutely special. But the average biologist believes that everything is continuous. We know that plants have DNA and humans have DNA, so we see that all of us are totally connected.
Do animals have culture?
There is quite a bit of evidence for cultural transformation in primates and many other animals, where they learn things from each other. For example, different groups of wild chimpanzees will have very different behaviors, different stone technology, tool technology, social customs, communication signals. We speak of cultural variation in the apes.
What’s one of the biggest misconceptions we have about animals?
We tend to think animals live in the present, that they don’t have a future and don’t have a past. But we know that’s not true. They can use tools to fix something for the future. In a Swiss zoo, orangutans had a skylight in their cage and dismantled the whole thing. That way they could spend summer nights on the roof of their building. Then in the morning before the caretakers came back, they would go back in the cage and put the skylight precisely back together. So no one ever noticed. On a nice summer night, it was better to be on the roof than inside the cage.
You say chimps display a sense of morality. How so?
They have a sense of fairness and are cooperative animals like we are. Let’s say I go hunting with you regularly and you always take the best pieces of meat and I only get little scraps. That’s not a good partnership for me. We find that chimpanzees and bonobos are sensitive to fairness. They can be empathic. They respond to the distress of others by reassuring them and by sharing food with them. We do experiments on this. Do they prefer outcomes that benefit only themselves, or do they prefer outcomes that benefit both chimpanzees?
How do you test that?
In a typical experiment, you put two chimpanzees who know each other side by side into two rooms, with mesh between them so they can see, hear, and smile at each other. Then you let one of them choose between two tokens. They get a bucket of tokens with different colors, let’s say blue and red tokens. If they pick a blue token and give it to us, they get rewarded. If they pick a red token, they get a reward but the partner also gets a reward at the same time. So it doesn’t make any difference for them because they get rewarded every time they give us a token. The only difference is, “Does my partner also get something?” What we find is that, over time, they start to prefer what we call the pro-social token, the token that rewards the two of them.
Tell us about Peony, an old female chimp in your colony at Yerkes.
Peony had arthritis and was very old, so she could barely move. She would try to climb into a climbing frame where a bunch of chimps were sitting and grooming each other. She wanted to join them, but she could barely get in there. The younger females would walk up to her, put their hands on her behind, and start pushing until she was up there with the rest. We’ve also seen cases where she started walking towards a water faucet, but, since it’s a very large enclosure and she walked with so much difficulty, a younger female would run ahead of her, take water in her own mouth, walk back to Peony, and then spit the water into her mouth so she wouldn’t need to walk all the way to the faucet. The acts of kindness made us interested in testing for altruistic behavior more systematically because the literature has claimed only humans care about others, that if primates are altruistic, it’s only to get favors in return.
And what did the tests reveal?
Chimpanzees have a lot of altruistic behavior towards unrelated individuals. This was tested in the field because people claimed that chimps were only altruistic toward relatives. You can measure the DNA of an individual, so you know who’s related to whom. Scientists found that most of the helping partnerships within groups of chimpanzees in the field are actually non-relatives, individuals who are not related to each other.
So humans aren’t the only ones who can recognize the pain or difficulty of another?
Humans overestimate the complexity of empathy. If you tell the average psychologist there’s empathy in animals, they will say that’s not possible. They think empathy means you consciously put yourself in the shoes of somebody else. We now know from human research that there’s a lot of empathy in automatic responses. If I’m frowning and looking sad, you’re going to frown and look sad because you will be affected by my facial emotions. If I’m laughing and smiling, you are going to laugh and smile.
Humans overestimate the complexity of empathy.
That bodily connection, usually called emotional contagion, is easily demonstrable in lots of animals. We do research on yawning contagion in chimpanzees. If I’m yawning, you are going to yawn at some point. We know from human studies that it’s correlated to empathy. People who are very empathetic are also very sensitive to the yawns of others, and they’re more likely to yawn in response to the yawns of someone they’re close to. So we tested chimpanzees. We showed them videotapes of yawning chimpanzees and they started yawning. They actually do it more if they see it in an individual they know, just like humans. These bodily connections are basically how empathy starts.
Is this the same as “mirror neurons,” or brain cells said to stimulate emotions we observe in others?
The mirror neuron is now often mentioned as a source of empathy, though there is quite a bit of controversy about the hyping of mirror neurons. But yes, mirror neurons are probably involved in this kind of emotional contagion. The body of the other is going to be represented in your brain. And we should never forget that mirror neurons were discovered not in humans, but in macaques. The evidence is that the neural substrate of empathy is very much present in all the primates. A chimpanzee who watches another chimpanzee screaming after losing a fight is going to be distressed himself. That may explain why chimpanzees console, and why we console others who are distressed.
Chimpanzees have complicated social lives. There’s a lot of jockeying for social status among both males and females. Do alpha males always rule the roost?
People always think the strongest male is dominant, and when he’s not so strong anymore, another male will take over. But I’ve known groups where the smallest male is the alpha male. He needs buddies who support him, so he needs to groom his supporters and share his food with them and sometimes share females with them. He cannot be completely exclusive in his mating rights.
He needs to build political alliances.
Yeah, he needs to bribe them. In captivity, females very often have quite a say. Since all the families live together, there’s an enormous power bloc which no male can get around. So if the alpha female doesn’t like a certain male, he’s in deep trouble because she’s going to support one of his rivals to take over the alpha position. It really becomes a political game.
You say that when an alpha male assaults a submissive female, other females will band together to protect the female under attack.
In captivity, forced copulation by males is basically impossible because the females as a bloc are opposed to that. Female chimpanzees don’t always support each other in other circumstances, but when a male tries to force himself onto a female, then all of a sudden they act in solidarity and he will regret what he tried to do. Now in the wild it’s more difficult because male chimpanzees don’t have all these females around, so the power difference between males and females is actually bigger than in captivity.
More than any other animal I know, chimps seem to have some understanding of their community as a whole.
You also write that after two males have been fighting, a female will sometimes force them to make up, and even take weapons out of their hands.
They confiscate weapons. Only females can do that. A male could not be a mediator because as soon as he walks into a scene like that, he’s going to be perceived as the buddy of one of the two. More than any other animal I know, chimps seem to have some understanding of their community as a whole. They seem to worry about the level of harmony in the group. Of course, they have a self-interest in doing that. Everyone benefits if the group is harmonious, so females will monitor the fights between males. If two males don’t reconcile after a fight, a high-ranking female will go over and start grooming one. After a few minutes, she will march to the other unruly male, bringing the first along with her. If he doesn’t want to follow, she will take his arm and make him follow. Then she will bring the two males together, at which point these males are supposed to groom each other. And they often do.
There are also certain high-ranking males who take what we call “the control role.” As soon as there’s a little fight—even the littlest fight between two juveniles—they will go over and break up the fight. And they are very impartial. They do not necessarily support their friends or their mother. It’s very important that they do this because small fights often escalate to big fights. I hear that’s also not unusual in human daycare centers. So it’s very important that they nip these things in the bud.
How do you explain that? We’ve been told for decades that selfishness drives natural selection. Only the strong survive.
That’s a simplification. The struggle for life is very often won not by struggling and fighting, but by having a better immune system, or better ears or eyes. Survival is not necessarily based on defeating somebody else. Yes, competition is part of the picture, but there are very strong counter-mechanisms that keep the society together. We live in groups because they are beneficial for us, so we need to keep our group together. That is also true for many animals.
Chimpanzees can be violent and dominance-oriented, and they can also be cooperative and friendly. So what species does that remind you of? People sometimes say you can’t call chimpanzees empathic if they kill each other. Well, the same argument applies to humans. Humans also have that whole spectrum. I feel that humans are more altruistic than any other species, but we are probably also the nastiest when it comes to our enemies.
Won’t chimps go to war against a rival group in another territory?
Yes, but chimpanzees don’t have genocide as far as we know. So we humans can be very proud that genocide is one of our distinguishing features. I also compare us with bonobos. Bonobos are equally close to us as chimpanzees and, in my opinion, are equally relevant. They’ve shown more empathy than what we’ve seen in chimpanzees.
You call them the “politically correct” primate.
They are the hippies of the primate world because they have sex instead of war. When two groups of bonobos meet in the forest there will be some hostility, but very soon they may overcome that. They will have sex with their neighbors and then they start grooming each other and the kids will play with kids in the other group. In all the years that we’ve studied bonobos in captivity and in the field, not a single case of lethal aggression has been documented.
You say sex is routine among bonobos.
It is very casual. It’s a little greeting of ten seconds and then it’s over. They rub their genitals together and they may touch each other’s genitals. Sometimes it gets a bit more involved. But most of the time it’s like, I slap you on the back.
Bonobos are also matriarchal. In what way are the females dominant?
The females are not individually dominant over males. They are smaller and less muscular, and they don’t have the big teeth that males have. But as a collective, female bonobos can travel together and be together. Collectively, they dominate the males.
Our evolutionary ancestors broke off from the common ancestor of chimpanzees and bonobos at about the same time. Is our common ancestor more bonobo-like or chimpanzee-like?
That’s the big question that we may never answer. The chimpanzee fits the thinking that humans are killer apes and only with time did we become peaceful. Another school of thinking doesn’t believe that we’ve always waged war because the evidence for warfare goes back only about 12,000 years, which coincides with the agricultural revolution. This group thinks bonobos are highly relevant.
So are humans inherently good or evil?
I’m of the school that we are inherently good and under certain circumstances do horrible things. The resistance to evolution that comes from fundamentalist Christians is partly a resistance to the idea that you could be moral without God.
Francis Collins, the prominent geneticist and director of the NIH, has said you can’t explain morality through evolution.
He must have read the wrong books. There has been a spate of books, starting with The Selfish Gene , that told us evolution cannot explain morality, that we’re born selfish and we don’t know where our morality comes from. These books are not Darwinian. If Collins read Darwin’s The Descent of Man , he would have seen that Darwin believed morality was part of the evolutionary story. We now know that moral judgments are intuitive. They are not necessarily a product of the reasoning that Kant talked about. We also know that very young children, sometimes before one year of age, are already picking the good guy over the bad guy in puppet shows. So the whole story has changed and neuroscientists now know that a lot of moral decision-making is rooted in evolutionary processes that we share with other primates.
Where does religion come in?
Religion is very interesting to me. My book is called The Bonobo and the Atheist partly because I’m objecting to the New Atheist who trashes religion as irrelevant and bad and morally wrong.
Yet you identify yourself as an atheist.
Yeah, but I really don’t care if God exists or not. If people can lead good lives by believing in God, that’s perfectly fine with me as long as they are not overly dogmatic. But some atheists have also become dogmatic.
Why are you bothered by atheists who don’t like religion and want to smash it?
Because religion is so inherently human that I don’t know what happens if you kick it out of society. Sigmund Freud wrote a whole book against religion and in the end he says that he is still not sure what would happen if we would remove it from society. It might not be good. We’ve seen the Communist experiment where they tried to get rid of religion. Stalin killed a lot of religious leaders and that experiment did not go well. Religion is so much part of human society. All human societies we know of have some sort of belief in the supernatural, so the question for me as a biologist is not so much whether religion is good or bad, but where does it come from? Why do we have this tendency? Is it some very special survival skill that humans developed? I believe morality came before religion, so religion cannot claim to be the source of human morality. But religion may contribute to maintaining morality in society.
Especially in large societies?
That’s the thinking of some people who study religion. Human groups used to be 100 or maybe 200 people, a bit like primate groups. In these small groups you can keep an eye on everybody if they’re not cooperative or if they cheat or lie. But that doesn’t work so well if you go to a big society of a thousand people or several million. At that point we needed another system to monitor morality. And what better way than imagining some being who’s omniscient, who can see you from every corner and even at night? So that may be why religions evolved and helped sustain these large societies.
But religion also has dark side.
Humans do terrible things to each other, sometimes in the name of God, sometimes without any religious reference. There is no proof that without religion we would be treating our enemies any better. We’re just not a particularly nice species when it comes to the out-group. But I have no patience with cruel religious practices, such as witch burning and genital mutilation. In this regard, I agree with the atheists that banning all of those superstitious behaviors would be a great relief.
Your take on religion is fascinating because you’re not religious yourself. You don’t believe in God but you seem to have what I would call a kind of “spiritual atheism.”
That’s an interesting term.
Well, you write about the experience of transcendence.
I believe the reason you find so many scientists who are agnostics and atheists is because we replace religion with something else. We do not see science as a religion, but we have a connection to the larger universe through our science. So that’s part of the transcendence that we feel.
But transcendence is more than just an understanding of the larger world. There’s a deeper, powerful emotional feeling that comes with it.
Yeah, it’s an emotional feeling of connection. Of course, every scientist, myself included, is very unhappy if you say this is mysterious and must be caused by some supernatural force. Still, we feel connected to a larger whole. I was recently at a meeting where an astronomer started crying. He choked up when he showed pictures of stars billions of light years away. He couldn’t speak, and then he composed himself and explained that ever since childhood, he’s been deeply affected by seeing these images. For the primatologist, most of us were completely fascinated the first time we looked into the eyes of an ape. We felt an immediate connection between apes and humans. We feel this connection at a very visceral level.
Do other primates have some form of religion?
I don’t think primates have religions, but they may have certain superstitions. For example, if a thunderstorm comes through with an enormous amount of noise and rain, male chimpanzees will put their hands up and start walking around bipedally, in a dancing sort of fashion. It’s called a rain dance and it has been observed with chimpanzees approaching a waterfall. We really don’t know why they do it. Are they impressed by what happens? Do they think they can stop it? Of course, that would be superstition. Are they somehow in awe of nature? They also react to death. We see that primates are very strongly affected by the death of others. They will not eat for days after one of their group members has died.
You could call it grieving. Let’s say a mother loses her child. It’s not only that she doesn’t eat; she screams or sits huddled in the corner. I think they know death is permanent, but we don’t know if they have that knowledge about themselves, like humans know they will die one day. That’s interesting because the afterlife plays very heavily in religion.
Primates are very strongly affected by the death of others. They will not eat for days after one of their group members has died.
Can you tell the story about the chimp named Lody at the Milwaukee County Zoo? It seems to be a remarkable story about memory and regret.
One day, Lody attacked the veterinarian who fed him. He bit off one of her fingers. Apes have such strong jaws, so they can do this in a fraction of a second. She came back from the hospital and the next day held up her bandaged hand to this male through the zoo window. As soon as he saw her, he ran to the corner and huddled in a sort of fetal position.
This veterinarian left the zoo, but then 15 years later, she came back to visit and Lody was still there. He immediately came up to her. She was standing at a railing, with her left hand out of sight. He kept trying to look at that hand but he couldn’t see it. Then she held it up and her hand was missing a finger. He looked at her hands and face, and she had this clear impression that after 15 years Lody still knew what he had done.
Steve Paulson is the executive producer of Wisconsin Public Radio’s nationally syndicated show To the Best of Our Knowledge. He’s the author of Atoms and Eden: Conversations on Religion and Science.