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Frans De Wall & Ira Flatow

Bonobo THE FORGOTTEN APE Frans De Wall, Ira Flatow, Mallory Heyer

Copyright © 2011 by Mallory Heyer All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law. For permission requests, write to the publisher, addressed “Attention: Permissions Coordinator,” at the address below. Minneapolis College of Art and Design 2427 First Avenue South Minneapolis, MN 55404 Ordering Information: Quantity sales. Special discounts are available on quantity purchases by corporations, associations, and others. For details, contact the publisher at the address above. Orders by U.S. trade bookstores and wholesalers. Please contact Big Distribution: Tel: (800) 800-8000; Fax: (800) 800-8001 or visit Printed in the United States of America Publisher’s Cataloging-in-Publication data Shakespeare, William. A title of a book : a subtitle of the same book / Bill Shakespeare ; with Ben Johnson. p. cm. ISBN 978-0-9000000-0-0 1. The main category of the book —History —Other category. 2. Another subject category —From one perspective. 3. More categories —And their modifiers. I. Johnson, Ben. II. Title. HF0000.A0 A00 2010 299.000 00–dc22 2010999999 First Edition 14 13 12 11 10 / 10 9 8 7 6 5 4 3 2 1

Bonobo THE FORGOTTEN APE Frans De Wall, Ira Flatow, Mallory Heyer


For DREW HEYER for always loving animals & finding ways to relate to them.

THE BONOBO (Pan paniscus) previously called the pygmy chimpanzee and less often, the dwarf or gracile chimpanzee, is a great ape and one of the two species making up the genus Pan. The other species in genus Pan is Pan troglodytes, or the common chimpanzee. Although the name "chimpanzee" is sometimes used to refer to both species together, it is usually understood as referring to the common chimpanzee, while Pan paniscus is usually referred to as the bonobo. It is distinguished by relatively long legs, pink lips, dark face and tail-tuft through adulthood, and parted long hair on its head. The bonobo is found in a 500,000 km2 (190,000 sq mi) area of the Congo Basin in the Democratic Republic of the Congo, Central Africa. The species is omnivorous and inhabits primary and secondary forests including seasonally inundated swamp forests.


An Interview Between Ira Flatow & Dr. Frans De Waal

Finding Your Inner Ape We're going to be going to pay a visit to some relatives: our closest primate relatives, actually, the bonobos and the chimps. And my next guest has spent many hours logging the behavior of these animals, trying to figure out how they negotiate the complexities of life in their respective communities. From violence to cooperation, to sex and empathy, how do the chimps and bonobos differ from us and each other? erotic and peaceful bonobo offers a fresh way of thinking about human ancestry And what do we have—what do we all have—in common?

is much sexier and more peaceful, friendlier, more empathic; a bit more elegant, also, in appearance. And so we can learn a lot from the bonobo, and that tells us quite a different story than the usual story you get about our human nature as nasty and selfish and violent. The bonobo tells a very different story about what we're like.

that or intimidate each other, but they go into a competitive mode. So that’s right there an example of something that changes it.

F » You write that ‘Compared with the male-centered chimpanzee, the femalecentered, erotic and peaceful bonobo offers a fresh way of thinking about human ancestry.’ That’s what you’re talking about.

F » I’m interested in the bonobos that are in the book. And lots of times we talk about, you know, human beings and chimps, but bonobos are–have a much different side to them, do they not?

DW » Yeah. And if the last common ancestor was maybe more bonobolike—we don’t know what kind of animal that was, but if it was bonobolike, then the whole story of the human evolutionary scenario becomes quite different.

DW » So bonobos are equally close to us genetically. People sometimes think that chimp is the only close relative that we have, but the bonobo is equally close. The bonobo is much sexier and more peaceful, friendlier, more empathic; a bit more elegant, also, in appearance. And so we can learn a lot from the bonobo, and that tells us quite a different story than the usual story you get about our human nature as nasty and selfish and violent. The bonobo tells a very different story.

for the last thirty years we have only heard the bad things about human nature DW » So bonobos are equally close to us genetically. People sometimes think that chimp is the only close relative that we have, but the bonobo is equally close. The bonobo


F » Give me an example of the difference between how a bonobo might act and how a chimpanzee might act in a typical case.

DW » OK. You give a cardboard box to some bonobos at the zoo; the first thing they do is have sex, and then they share the box and play with it and do things with it. You give it to chimpanzees; they first need to figure out who’s getting the box and they will beat each other up or something like

F » And lots of times we talk about, you know, human beings and chimps, but bonobos are–have a much different side to them, do they not?

F » And you think enough attention has not been paid to our bonobo side of us vs. our chimp side. DW » That has been completely ignored. For the last 30 years we have only heard bad things about human nature, and the bonobo gives us a new look at that. F » And we say we’re acting like a monkey or something; you know, that’s been a derogatory phrase. But it would be complimentary to say we’re acting like bonobos. DW » That would be OK. Yeah. F » If we all, you know, acted more like bonobos, as you say, who knows where the world might have been. Are they


DW » Yeah. You must have heard about the genome issue that came out in Nature just a month ago. And the chimpanzee is 98.5 percent identical to us genetically, and the same is true for the bonobo. So they’re exactly equally close to us, so there’s absolutely no reason to take the chimp always as model, as people have been doing.

building all the time. And after a while, after two weeks of the caretakers trying to get him to move to particular places, another male would take his hand and lead him to these places. Well, that’s interesting, because it means he understood that this male was handicapped and had trouble. He understood the commands of the caretakers, and he was helping out. And that kind of actions, where you put yourself in the shoes of somebody else, are very typical of the bonobo.

F » And how—and was Jane Goodall responsible for that model that we have with the chimp, do you think?

F » You also give an interesting example with an injured bird that flew into the cave, flew into the glass...

DW » Not really. I think that was actually before her that the chimp became our prime model, because a chimp has been known so much longer than the bonobo. But it is true that when the discoveries of chimpanzee violence came along and chimpanzees killing each other in different territories, that all clicked together with the killer ape theories that were out there by Konrad Lorenz and other people—Robert Ardrey.

DW » Yeah. A bonobo had a bird in a cage. It was stunned. And instead of playing with it or eating it or whatever other primates might do, the female took the bonobo and climbed to the highest point of her enclosure and enfolded the little wings of the bird, like a little airplane, and sent it out in the sky, which means that she was taking a look at the world from the perspective of a bird, which is very unusual. Of course, with another ape, she would never have done something like this. That would have been inappropriate. But with the bird, it was the appropriate kind of helping response.

equal—are we equally distant genetically or on the tree there from each one of them equally?

And so the whole picture became like we are killer apes, that’s all we are, and as soon as people do something bad, like in Rwanda or Bosnia or whatever, we say they’re acting like animals. And so as soon as we do something negative, we’re compared with our animal side. As soon as we do something nice and

F » Does that mean that the bonobos have consciousness, do you think? DW » Well, I think all animals have conscious to some degree. I don’t know exactly what consciousness is. That’s my problem, obviously.

we claim it as humane, so we claim it as our own species positive, we claim that as humane so we claim it as our own species. But in animals, in many animals, but in bonobos in particular, you can find all those positive tendencies as well. F » I was shocked to see the many examples that you gave of a very human characteristic. And, you know, we always say what separates us from the other animals is our ability to have consciousness and have feeling, and the bonobos have empathy. And you give a couple of different, really interesting examples, how they really are empathetic. DW » Yeah. Let me give an example so—at one zoo they had a male bonobo who had a heart condition, and as a result he wasn’t too bright, and he would get lost it the [1] Continuous research is done to see if animals have a sense of empathy. Other animals that have been tested include dolphins, elephants, and rats. Empathy has been found in all of the listed animals.

F » Right. How would you define consciousness? DW » That’s the problem. [1] People say, ‘Are animals conscious?’ Then I ask them, ‘What is it?’ And then we’re stuck, usually.

F » Right. But is there, say—so you’re saying that we have the chimp side of us, but we have the bonobo side genetically that we do not give ourselves enough credit for—or we don’t give the bonobos enough credit having that kind of stuff. DW » Yeah. We have two sides to us. So when we’re at our—when we’re showing bad behavior, we are worse than any other

i call us bipolar apes. we have both the nasty side and the positive side 13


still are, but I always notice that people are actually delighted that we have cousins like that who are in many ways very humanlike.

because evolution tinkers. Evolution plays around with things and modifies them, but it never designs from scratch.’

F » So what can we—can we actually— you know, what can we learn, and what as a scientist can you learn about human behavior by watching the bonobos and the chimps?

And so evolution is a beautiful alternative theory to intelligent design, and since intelligent design is supposed to be testable, I think we would very soon find that any test we do, it doesn’t hold up. So we can use it as a sort of foil and explain how much more powerful evolutionary theory is in explaining what we see around us.

DW » Well, you can sort of triangulate now, because we have two close relatives who are quite different. And so if people say—some pessimists, they will say, ‘We will always be aggressive. We will always have war, because we come from a lineage of animals who kill each other.’ Then you can bring up the bonobo and say, ‘The bonobo’s equally close to us as the chimp, and they don’t kill each other.’ So in that sense, they already give us a different perspective on human nature. And I consider us basically apes. I know that Darwin said that we descended from the apes, but really, we are apes. We’re not that

if we give them a chance, they would keep evolving different. We walk bipedally and we have big brains, but that’s about the only difference that exists. F » Mm-hmm. While we’re talking about evolution, I can’t—you know, it’s hard to ignore what’s going on in the school systems and legal suits about teaching of, you know, creationism, intelligent design, whatever you like to talk to it. You must get asked this all the time when you talk about the apes, you know. How do you respond to people? I mean, you go on talk shows; you’re talking about the book. The calls must be coming in from the heartland all the time. DW » Constantly. We constantly get calls about ID, intelligent design. I’ve now reached a point that I almost say, ‘Well, let’s teach it,’ because it’s an excellent opportunity to show that it’s all nonsense. It’s all junk, basically, because if intelligent design is true it’s based on the premise that we are sort of perfectly designed and that nature is perfectly designed. But we can test those sort of ideas. And if you take, for example, the flaws in design that exist—many flaws exist—the human back is a prime example of a flaw. We are descendants from four-legged animals, but our back never really caught up with our bipedal gait. And our back problems that so many people have is a flaw in the design. And we can come up with many of these examples, and basically, the evolutionary biologist looks at that and says,‘Well, that’s 14

F » Are primates still evolving, do you think, or... DW » We probably stopped evolving, except for disease. When it comes to disease, we have to keep up, and we keep evolving, and the diseases keep evolving. And the flu virus is a good example. I think we have basically stopped because we are interfering too much with evolutionary pressures. But the other primates, I think, if we would give them a chance—which we’re not really doing... F » We’re eating them. DW » Yeah, we’re eating them and we’re destroying their habitat. But if we would give them a chance, they would keep evolving. F » I have a question about bonobos and their ability to learn language. I know there’s a bonobo named Kanzi at Emory, and Kanzi seems to be better than almost any other ape at learning language. And I wondered if that—I mean, my theory about that is that it has to do with the bonobo’s highly evolved social sort of way of being. Could you speak to that at all? DW » Yeah. I’m not sure that what bonobos have, including Kanzi, is actually language. Kanzi is extremely good at understanding spoken English, and that may relate, as you say, to his sensitivity to the moods of others, the intentions of others, being in tune with everybody else, and then adding to that his language knowledge, which is pretty impressive. But as far as producing language, I’m not so convinced that that’s what they’re doing. F » Didn’t you write in your book—was it Kanzi who actually helped you teach another bonobo to speak English or understand English? DW » Kanzi interfered when someone tried to—What was it again? They tried to speak English to a naive bonobo, and the bonobo didn’t understand anything, and Kanzi then instructed that bonobo what was meant. So, for example, someone would say, ‘Do you want to groom?’ and then Kanzi would make the grooming movements on that other bonobo, so—showing that he can even go.


F » I was just wondering whether bonobos could be taught sign language, maybe like some of the apes that have been taught. DW » Yeah. Bonobos have been taught things with symbols, symbol use. And so their language abilities—I don’t know how well-developed they are, but they have, certainly, some of that. And the language debate is sort of interesting, because, you know, in the old days linguists would define language as symbolic communication. And then when the apes came along, chimpanzees, bonobos, gorillas, who were capable of symbolic communication, the linguists immediately moved it to syntax. They said, `The essence of language is syntax.’ And so the linguists have been moving the definition of language around in order to keep the apes out, which is a very common strategy in all of science, basically. As soon as apes can do something, you’re going to get redefinitions in order to keep the human status up to where it was. F » They move the goalposts. DW » Yeah, that’s what they’re doing all the time. F » And so as these bonobos show—I was just seeing something the other day where—I remember which apes were making tools now. They saw—and they’d never seen them make tools before, the kind of... DW » That’s right. Gorillas. Wild gorillas using tools. F » Yeah. Yeah. DW » Well, that’s another funny thing, is in captivity all the apes are good tool users. So for example, the best tool users are orangutans in captivity. But in the field for 30 years all they had seen orangutans do is scratch their butt with a stick or something like that. And so people always said, ‘Well, in the wild they’re not doing it.’ But then, of course, orangutans were discovered to do it, and usually you can assume if animals can do something in captivity that is very impressive, they’re using it one way or another in the field. F » And so you just haven’t seen it happen... F » Talking about these bonobos and the apes. So you write in your book about some interesting observations you made about the “Larry King” show, talk show. Tell me why you went in that direction in talking about Larry King and the observations themselves. DW » Well, the observation I did not do myself, but I feel that the social sciences are totally ignoring the topic of power and domi-

nance in human relationships. If you open a textbook in social psychology, they barely mention power and dominance and they only mention it as abuse, abuse of power or something like that. But power and dominance are very prevalent and very common and very well-detected in human society, and soon as you walk into a room you see what the power of relationships are—we’re very sensitive to it. And then the “Larry King” show, of course, what they did is they taped his interviews and they noticed that in the low frequencies of the voice, which is called the low hum, there are adjustment being made. So for example, your low hum is different from my low hum, but if you talk with me—let’s say I’m a high-ranking guest—in Larry King’s case he had, for example, Bill Clinton on—that was a high-ranking guest— he would adjust his hum to Bill Clinton’s. Whereas if he had a low-ranking guest— according to that particular article the lowest-ranking guest was Dan Quayle—if he had a low-ranking guest the low-ranking guest would adjust his low hum to Larry King. And so they found in that study, and then they followed it up with many other experiments, that we are constantly communicating status to each other by this low hum. We do it unconsciously. We can barely detect it but the machines can detect it. So even if you talk with your boss over the telephone, you’re communicating status difference with him. And so that’s a very important part of our social being, but it is to a large degree neglected, I think. F » That’s different than body language then. DW » The body language, of course, also very important. The swagger that Bush has, for example, you know, putting his arms aside is very chimpanzeelike posture with the arms out and he doesn’t have the hair that he can stand up like the chimps do, but these kind of swaggers that leaders have. Bill Clinton also had a swagger. And those are very strong status indicators. F » In human society we have tremendous diversity in culture. Anybody that’s ever been to Sri Lanka or Cambodia would be struck by how much hugging there is or the different

social sciences are ignoring the topic of power and dominance in human relationships 15


humans don’t like to get less than somebody else. And so if you have a situation where two people come every time for a particular chimp, and give that chimp a lot of good food and no one else is getting that, that’s a bad situation. That would be like you having six kids and feeding one of them always goodies and the other ones never get anything. That would create resentment. And so we actually do experiments on that. I did an experiment with Sarah Brosnan on capuchin monkeys where we would give a monkey as a reward a piece of cucumber. And if you do that—put two monkeys side by side and you reward them for a certain activity with pieces of cucumber, they will do it 25 times in a row. But if you give one of them grapes and the other one keeps getting the cucumber, grapes are far more attractive to them than cucumber pieces. The one who gets the cucumber then becomes angry and becomes agitated. First of all, they start refusing to do the task, but they also throw the cucumber pieces out of their cage at you. And so they—we call it inequity aversion. They don’t like inequity, and all the primates

by 2050 most of those animals will be gone I think they have a very strong sensitivity to it. And of course, humans in our society—we have this sense of fairness which relates very strongly to that sort of avoidance of inequity. F » Right. And so you’re saying that you can use the apes as a laboratory to study these primal emotions that we all have. DW » Yeah, because there was a tendency— not anymore, I think—but in economics to look at humans as completely rational beings. We are completely rational optimizers of our benefits. But now economists are coming to the realization that humans are emotional beings and that we sometimes act irrationally. Because, for example, throwing good pieces of cucumber out of your cage is not a rational thing to do. And we are the same. If I hear tomorrow that my closest college who does the same work as I do has a salary that is twice my size, I get very pissed off and I may actually quit my job, which is an irrational act because until that time I was perfectly happy. F » Right. And you would say, I would imagine, that if you were studying “animals,” you would say they wouldn’t do that because that’s not a survival technique to throw your food away. DW » But we also think that there’s an 16

evolutionary reason for these particular emotions. For example, in the case of capuchin monkey or the chimpanzee, they’re very cooperative primates. Now if you’re highly cooperative, you need to watch what you get. You—I don’t want to cooperate with you if I don’t get a fair share afterwards. And so when you’re a coop-erator, you need to pay attention to ‘Do I get less or do I get more than somebody else?’ F » Do bonobos do a lot of wheeling and dealing, like we humans do? DW » Yeah, they’re all transactionalists, what you could call it, like ‘I will help you become the alpha male but then you give me access to the females, and if you don’t then I withdraw my support and you’re gone also.’ You know, so, yeah, that kind of political deals are very common. F » And do the females—do they take advantage of, you know, the sexual desires for them to get what they might, you know, get out of the males? DW » You use every weapon that you have and, yes, the females have that as a weapon, and for example, bonobo females— there’s sort of two sides to that. The older bonobo females are dominant over males collectively. F » Right. DW » And so they get what they want anyway. But the younger females—they are not yet dominant over males and they use sex to get favors. And so yeah, they will approach a male who has good food and have sex with him and then get a lot of that food, yeah. F » So the older ones are saying, ‘I have done that trick. I have learned how to be smarter.’ DW » The older ones have very effective alliances and that’s how they dominate the males, because an adult female bonobo is not bigger than a male. She’s smaller than a male and she doesn’t have the canine teeth of a male, so she has to work together with other females; otherwise they would never be dominant. F » And they cooperate. DW » They do. They do. They’re very good at that. Yeah. F » I’m curious about the comparison in brain sizes between chimpanzees and bonobos and I’m struck to this thought of thinking about the comparison in brain sizes between Neanderthals and Homo sapiens, Neanderthals having the larger brain size and yet being eradicated by the Homo sapiens, and I was wondering if you could comment on


any comparisons that have been done. DW » Yeah, I am not sure that brains explain everything, so for example, Neanderthals—yes, they have a slightly larger brain than the human brain, but maybe their immune system was not up to par, or maybe something else came up that—maybe they were feeding on other sources than we were, and so I’m not sure that brain size is necessarily the measure of everything. But it is true that humans have a brain size that are three times that of a chimpanzee, and so we are definitely quite a bit smarter than a chimpanzee. Between chimps and bonobos, we don’t know much of a difference between those two. F » I have noticed very recently that there’s a large amount of new information being published in the medical journals as a result of the sequencing of the chimp genome. And although a lot of that information is very exciting, nothing is usually mentioned about the importance of also studying the behavior of these animals in connection with the genetics and also the importance, these days, of the conservation because they are more endangered than they ever have been, and I think that scientists need to be bringing that to the public more. DW » Well, the situation in the field is definitely very dire; it’s very bad. I used to be fairly optimistic and think, well, there will be enough bonobos and chimps surviving, but nowadays I hear that the graphs are that by 2040 or 2050 most of those animals will be gone, and that’s because most of the habitat will be gone. And so the situation in the field is pretty terrible. As far as genetics and the genetic differences between bonobos and chimpanzees go, [2] there was a very recent study I think six months ago, which actually came out of the Yerkes Primate Center but by a different team of people, where they found a little piece of dna that is involved in affiliation and bonding. It’s a microsatellite, it’s called, and that little piece of dna that they found it in humans—it’s related to hormones that relate to bondingtthey said, well, let’s look at chimpanzees and bonobos. And guess what? What they found is that the bonobos have it and the chimps don’t. So that makes us think– that’s very exciting news because it makes us think that maybe the last common ancestor of humans, chimps and bonobos had that sort of bonding gene, or whatever it is, a social gene, that is absent in the chimpanzee. And so there is now some speculation in that regard. F » You write that political ideology and biology are awkward bedfellows, but you do make the case that we can learn something about what makes a success[2] Thus far little or no evidence in monkeys. Like us, of course, chimpanzees belong to the Hominoidea, a branch that split off long ago from the rest of the primate tree. They are thus genetically much closer to us than are baboons.

ful society from watching the apes. And can we draw any lessons here in the aftermath of Hurricane Katrina? DW » Well, that’s an interesting topic because when that happens, the people who were locked up in the dome in Louisiana, they said, `They’re treating us like animals; they’re leaving us behind like animals.’ And I was thinking, well, that’s not what most animals will do. There are animals who would leave you behind—sharks will leave you behind probably. But social animals such as dolphins and chimpanzees and bonobos and so on—they don’t leave the unfortunate behind. So there is this view in society, especially actually in American society because social Darwinism has been so important here— there is this view that the world is a jungle, everyone competes with everyone and we will all be better off that way. But actually that’s not how the Darwinian world works. The Darwinian world has produced very social animals, such as chimps, bonobos and us, which don’t leave the unfortunate behind. So for example, in the forest of Tai Forest in Ivory Coast, they have observed the chimpanzees when they are heavily injured, which sometimes happens by leopards—the others slow down, they lick the wounds of the ones who are injured, they share their food with them, and so there is actually a tendency to take care of those who are less fortunate. And so Hurricane Katrina exposed actually a lot of callousness in this particular society, and if people say that that’s the way the natural world works, I object to that because that’s not necessarily how it works. F » And you write in—you show in examples that cooperation breaks down if the benefits aren’t shared by all the participants. DW » Yeah, that relates to the equity issue. Is that if we are cooperators and we work together and we get good benefits out of that and you claim everything, I lose interest in the operation obviously, and primates are exactly the same. So they’re willing to cooperate, but they watch what they get out of it, and so a certain amount of equity and fairness in society needs to be there. Otherwise, the cooperation is going to break down. F » So how much have we—I mean, the message of your book I think is that we really are parts of these chimps and parts of these bonobos and if we just would spend some time looking at those parts we might learn a lot about ourselves. DW » Yeah. F » And how do we spend that time? How do we find it, where do we look? 17


Do we go watch them?—I mean, like you do or... DW » Yeah. Well, I’m paid for that. You know, so that’s different from other people. So I’m paid for it, and my students work on it and write dissertations on it. But the regular person—what you can do is indeed go to the zoo, but then you should watch more than two minutes because the average—we have clocked people at the zoo the average is two minutes, and then they say—they walk away and then they say, ‘I could watch them for hours.’ Well, I can tell you, do watch them for hours. And if you do spend time—if you go to a zoo and you decide, OK, for three hours I’m going to watch these primates, in those three hours you’re going to see very interesting things, much more interesting than what you get to see in two minutes. F » Where can you find bonobos in zoos? Are they—they’re not as common. DW » No, the San Diego Zoo, the Cincinnati Zoo, the Columbus Zoo, the Milwaukee Zoo, the Jacksonville Zoo—there are not many bonobos in the world, but we have them in this country. F » Where are bonobos found in the wild? Where do we... DW » They only live in what is now ironically called the Democratic Republic of the Congo, which is basically a big political mess, and it’s in area about the size of Great Britain—a forested area. It’s still one of the best-protected forested areas, but they’re already logging in there and there’s—yeah, and we think there’s maybe 10 to 20,000 bonobos left there. F » All right. And they’re dying out because of their—are they being eaten like the chimps are being eaten? DW » They are being hunted. Yes, it’s all very precarious, yeah. F » You know, you talked about you get paid to do this and it sounds like a great job, but you reveal in your book that it can get a bit tedious at times. DW » Yeah, because we’re not just sitting

one of the biggest compliments that chimps can pay to you is to treat you like furniture 18

there and watching them. F » Give us an idea of the life of a bonobo watcher. DW » You have a keyboard in front of you and you type in the data, and if a big fight breaks out among the chimpanzees or bonobos, I cannot handle it on a keyboard. I have to speak it in or videotape it, so I speak in a narrative or I videotape it, and then afterwards we code it. But basically you end up, I have it in the computer now I think, 200,000 lines of behavior that I can analyze. So then I need to write a program or have a programmer do that, and go through all the data. So the science part of it, which ends up with quantification and graphs and all of this, is very tedious. The fun is just to talk to the chimps and see them and say hello to them and stuff like it. F » And you mention that one of the biggest compliments that chimps can pay to you is to treat you like furniture. DW » Yeah, they do that. Most of the time when I walk by the enclosure or look at them, they do as if I don’t exist. What I always find very funny is if I bring a guest. They hate strangers, so me they’re completely used to, but they don’t like strangers. And so when I bring a guest, they’re mad at me for bringingthe guest, so they will spit at me and throw stuff at me, which they never do, but they do that because that guest is there. And they don’t do it at the guest ‘cause apparently they blame me rather than that person. F » Can you do what humans do and bring them some gifts to mollify them? DW » Oh, they will certainly go for that. Another funny story is that I have an office that overlooks the chimpanzees. And one day I came in and my whole window was spattered with mud, and I didn’t understand it because they never throw anything at that window. And then I heard that some people had been in there laying a new cable, and so there had been some strangers in my office without me present, and that’s about the worst thing that can happen according to the chimpanzees and so they have sprayed the whole window with mud. F » Wow. In the last minute that we have, where is the cutting edge of your research, what would you like to know? DW » We’re doing a lot of research on empathy. I think empathy is a very understudied topic. In humans it’s a bit better-studied; in children certainly it’s studied. But in animals it’s ignored, and that’s partly because there’s a taboo on emotions in animals, but that’s disappearing at the moment, and so I think it is time to start studying empathy


and emotional connectiveness in animals. F » Do you think the bonobos might be getting less attention because they are so sexual and you can’t show that on—can’t show, you know, copulation of bonobos on television? DW » In the US there was a big problem, and that’s why when Frans Lanting, the nature photographer, and I did a book on bonobos, the first thing we did is publish it in Germany. And the Germans put copulating bonobos on the front of their magazines and everything, and that’s how we started out. And then we moved the operation to the US and tried to publish, and we did publish in the US. But in the US, you know, it’s an extremely prudish place, and so bonobos were a problem. And to some degree, they still are, but I always notice that people are actually delighted that we have cousins like that who are in many ways very humanlike. F » Yeah, there was that story about the boy who fell into the habitat.

it is time to start studying empathy and emotional connectiveness in animals. DW » Yeah, that was at the Brookfield Zoo where a boy fell in with gorillas and a gorilla female saved him and brought him to safety, and that actually opened the eyes of many people, and Bill Clinton held up Binti Jua the gorilla as an example for humanity, and so yeah, that made a big impression, but actually what the gorilla did was not that special because a gorilla would do something like that for any other gorilla, so in this case it was just applied to us. F » It’s all in the family. Thank you very much, Dr. de Waal, for talking with us. DW » You’re welcome. «



An Essay By Dr. Frans De Waal

Bonobo: The Forgotten Ape THE LAST APE

When the lively, penetrating eyes lock with ours and challenge us to reveal who we are, we know right away that we are not looking at a “mere” animal, but at a creature of considerable intellect with a secure sense of its place in the world. We are meeting a member of the same tailless, flat-chasted, long-armed primate family to which we ourselves and only a handful of other species belong. We feel the age-old connection before we can stop to think, as people are wont to do, how different we are. Bonobos will not let us indulge in this thought for long: in everything they do, they resemble us. A complaining youngster will pout his lips like an unhappy child or stretch out an open hand to beg for food. In the midst of sexual intercourse, a female may squeal with apparent pleasure. And at play, bonobos utter coarse laughs when their partners tickle their bellies or armpits. There is no escape, we are looking at an animal so akin to ourselves that the dividing line is seriously blurred with this point of view. Whereas the bonobo amazes and delights many people, the implications of its behavior for theories of human evolution are sometimes inconvenient. These apes fail to fit traditional scenarios, yet they are as close to us as chimpanzees, the species on which much ancestral human behavior has been modeled. Had bonobos been known earlier, reconstructions of human evolution might have emphasized sexual relations, equality between males and females, and the origin of the family, instead of war, hunting, tool technology, and other masculine fortes. Bonobo society seems ruled by the “Make Love, Not War” slogan of the 1960s rather than the myth of a bloodthirsty killer ape that has dominated textbooks for at least three decades.


In 1925, Raymond Dart announced the discovery of a crucial missing link in the human fossil record. This bipedal hominid with apelike features brought the human lineage considerably closer to that of the apes than previously held possible. It also provided the first indication that Charles Darwin had been correct in suggesting Africa,


rather than Asia or Europe, as the cradle of humanity. On the basis of evidence encountered at the discovery site, Dart speculated that Australopithecus must have been a carnivore who ate his prey alive, dismembering them limb from limb, slaking his thirst with their warm blood. The killer-ape myth is the science writer Robert Ardrey’s dramatization of these and other ideas, including the proposition that war derives from hunting, and that cultural progress is impossible without aggressivity. The renowned ethologist Konrad Lorenz added that whereas “professional” predators, such as lions and wolves, evolved powerful inhibitions keeping them from turning their weaponry against their own kind, humans have unfortunately not had time to evolve in this direction. Descended from vegetarian ancestors, we became meat-eaters almost overnight. As a result, our species lacks the appropriate checks and balances on intraspecific killing. It has been suggested that the tremendous appeal of this scenario had more to do with the genocide of World War II than with fossil finds. Confidence in human nature was at a low after the war, and the popularizations of Ardrey and Lorenz merely reinforced the misanthropic mood. In A View to a Death in the Morning, Matt Cartmill summarizes the impact of the by now antiquated idea that the lust to kill has made us what we are: During the 1960s, the central propositions of the hunting hypothesis—that hunting and its selection pressures had made men and women out of apelike ancestors, instilled a taste for violence in them, estranged them from the animal kingdom, and excluded them from the order of nature—became familiar themes of the national culture, and the picture of Homo sapiens as a mentally unbalanced predator, threatening an otherwise harmonious natural realm became so pervasive that it ceased to provoke comment... Millions of moviegoers in 1968 absorbed Dart’s whole theory in one stunning image from Stanley Kubrick’s film 2001, in which an australopithecine who had just used a zebra femur to commit the world’s first murder hurls the bone gleefully in the air--and it turns into an orbiting spacecraft. Ironically, it is now believed that Australopithecus, rather than having been a predator himself, was a favorite food for large carnivores. The damage to fossil skulls, which Dart interpreted as evidence for


is thus far little or no evidence in monkeys. Like us, of course, chimpanzees belong to the Hominoidea, a branch that split off long ago from the rest of the primate tree. They are thus genetically much closer to us than are baboons. Whereas selection of the chimpanzee as the touchstone of human evolution represented a great improvement over the baboon, one aspect of the models did not need to be adjusted: male superiority remained the “natural” state of affairs. In both chimpanzees and baboons, males are conspicuously dominant over females. In baboons, males are not only twice the size of females, they are equipped with canine teeth as Bonobos are a very affectionate species. So much so that it is uncomfortable for more conservative people to see. This is why Bonobos aren't as common in zoos in America as they are in Europe. formidable as a panther’s, whereas females lack such weaponry. Sexual dimorphism may be less dramatic in the chimpanzee, but in this species, too, males reign supreme, and club-wielding man-apes, turns out to be perfectly consistent with often brutally. It is extremely unusual for a fully grown, healthy predation by leopards and hyenas. In all likelihood, therefore, the male chimpanzee to be dominated by a female. beginnings of our lineage were marked more by fear than ferocity.


Bonobos are not on their way to becoming human any more than we are on our way to becoming like them. Both of us are well-established, highly evolved species. We can learn something about ourselves from watching bonobos, though, because our two species share an ancestor, who is believed to have lived a “mere” six million years or so ago. Possibly, bonobos have retained traits of this ancestor that we find hard to recognize in ourselves, or that we are not used to contemplating in an evolutionary light. Not too long ago, a much more distant relative, the savanna baboon, was regarded as the best living model of ancestral human behavior. These ground-dwelling primates are adapted to the sort of ecological conditions that protohominids must have faced after they descended from the trees. The baboon model was largely abandoned, however, when it became clear that a number of fundamental human characteristics are absent or only minimally developed in them, yet present in chimpanzees. Cooperative hunting, food-sharing, tool use, power politics, and primitive warfare have been observed in chimpanzees, who are also capable of learning symbolic communication, such as sign language, in the laboratory. Moreover, these apes recognize themselves in mirrors—an index of self-awareness for which there

Enter the bonobo, which is best characterized as a female-centered, egalitarian primate species that substitutes sex for aggression. It is impossible to understand the social life of this ape without attention to its sex life: the two are inseparable. Whereas in most other species, sexual behavior is a fairly distinct category, in the bonobo it has become an integral part of social relationships, and not just between males and females. Bonobos engage in sex in virtually every partner combination: male-male, male-female, female-female, male-juvenile, female-juvenile, and so on. The frequency of sexual contact is also higher than among most other primates. The bonobo’s rate of reproduction is low, however. In the wild, it is approximately the same as that of the chimpanzee, with single births to a female at intervals of around five years. This combination of sexual appetite and slow reproduction sounds familiar, of course: nonreproductive sex is a prominent trait of our own species. If the sole purpose of sex is procreation, as some religious doctrines would have it, why has the average size of families in industrialized nations dropped to fewer than two children, despite the fact that countless human couples in those countries copulate regularly? Per-



haps they do so because it feels good, hence tends to become addictive. Yet this automatically raises the question: Why does it have this effect on people? After all, most other animals restrict their mating activity to a particular season or a couple of days in their ovulatory cycles; they do not seem to feel any sexual needs divorced from reproduction. The bonobo, with its varied, almost imaginative, eroticism, may help us see sexual relations in a broader context. Certain aspects of human sexuality, such as pleasure, love, and bonding, tend to be overlooked by reproduction-oriented ideologies. The possibility that these aspects have characterized our lineage from very early on has serious implications, given how often moralizing relies on claims about the naturalness or unnaturalness of behavior: what is natural is generally equated with what is good and acceptable. The truth is that if bonobo behavior provides any hints, very few human sexual practices can be dismissed as “unnatural.� Because the role of sex in society is such a loaded and controversial issue, scientists have tended to downplay this side of bonobo behavior, whereas the few journalists who have written about the species have naturally hyped it. In this book, I hope to strike a balance: I intend to give the topic the attention it deserves, without reducing bonobos to the lustful satyrs that our closest relations once were considered to be. Sexual encounters of the bonobo kind are strikingly casual, almost more affectionate than erotic. If the apes themselves are so relaxed about it, it seems inappropriate for us to give in to typically human obsessions. In addition, there is a lot more to bonobo natural history than sex. The entire social organization of the species is fascinating, as is its mode of communication, raising of offspring, remarkable intelligence, and status in the wild. The whole creature deserves attention, not just part of it. In the past few years, many different strands of knowledge have come together concerning this most enigmatic ape. The findings command attention, as the bonobo is just as a close to us as its sibling species, the chimpanzee. to one According to dna analyses, we share over 98 percent of our genetic material with each of these two apes. And not only are not they our nearest Three bonobo apes working together to groom one another. The bonobo has a relatives; we are theirs! That is, when genetic makeup strong sense of community, they constantly work together.



of a chimpanzee or bonobo matches ours more closely than that of any other animal, including other primates, such as gorillas, tradi No wonder Carl Linnaeus, who imposed the taxonomic division between humans and apes, regretted his decision later in life. The distinction is now regarded as wholly artificial. In terms of family resemblance, only two options exist: either we are one of them or they are one of us.


Years ago, when the conservator of mammals at the Amsterdam Zoological Museum happened to dust off the stuffed remains of an ape named “Mafuca,” he immediately recognized its bonobo features despite the label, which said it was a chimpanzee. During Mafuca’s short life, from 1911 through 1916, bonobos were not yet recognized as a separate species, even though a few keen observers already had an inkling of the difference. In 1916, a perceptive Dutch naturalist, Anton Portielje, speculated in a guide to the Amsterdam Zoo that the hugely popular Mafuca might represent a new primate species. A few years later, Robert Yerkes, the American pioneer of ape research, contrasted “Prince Chim,” an individual now known to have been a bonobo, with a chimpanzee, noting: “Complete descriptions of the physique of the two animals might suggest the query as to whether they were both chimpanzees.” For all intents and purposes, therefore, the species distinction between bonobo and chimpanzee ought to be credited to behavioral scientists such as Portielje and Yerkes. It was only when anatomists reached the same conclusion, however, that the world paid attention. [3] The distinction, first made in 1929, carried tremendous weight: the bonobo became one of the last large mammals to be known to science. Rather than in a lush African setting, the historic discovery took place in a colonial Belgian museum following the inspection of a skull that, because it was undersized, was thought to have belonged to a juvenile chimpanzee. In immature animals, however, the sutures between skull bones ought to be separated, whereas in this specimen they were fused. Concluding that it must have belonged to an adult with an unusually small head, Ernst Schwarz, a German anatomist, declared that he had stumbled

[3] Reynolds’s chief argument was that the original drawing shows a cutaneous connection between the second and third digits of the ape’s right foot. A new primate species. A few years later, Robert Yerkes, the American pioneer of ape research, contrasted “Prince Chim,” an individual now known to have been a bonobo.

as well as making it sound too much as if the bonobo is merely a smaller version of its congener. Others, in turn, say the name “bonobo” is meaningless and probably derives from a misspelling on a shipping crate of “Bolobo,” a town in Zaire. The label “bonobo” has stuck, though, not least because it respects its bearer as a fully distinct species, rather than as, so to speak, the poor man’s miniature chimp. In addition, “bonobo” has a happy ring to it that befits the animal’s nature. Primatologists acquainted with its behavior have even jokingly begun to employ the name as a verb, as in “We’re gonna bonobo tonight.” (The meaning of this expression will be left to the reader’s imagination!) To complete these notes on the discovery of the last ape, it has recently come to light that, ironically, the bonobo may have been known to science longer than any other great ape. The earliest accurate description of an ape was produced, in 1641, by Nicolaas Tulp, a Dutch anatomist of great repute, immortalized in Rembrandt’s The Anatomy Lesson. The ape cadaver that Tulp dissected resembled a human body so closely in its structural details, musculature, organs, and so on, that he commented that it would be hard to find one egg more like another. Although Tulp baptized his specimen an Indian satyr, adding that the local people called it an “orang-outang,” it had come straight from Africa. Only its name came from the East Indies. Tulp’s gravure, faithfully replicated over and over in books of the seventeenth and eighteenth centuries, appears to show a female chimpanzee. At least this was the consensus until a British primatologist, Vernon Reynolds, asserted that Tulp’s satyr could very well have been a bonobo. Reynolds’s chief argument was that the original drawing shows a cutaneous connection between the second and third digits of the ape’s right foot. Such “webbing” between toes is much more common in bonobos than in chimpanzees. Furthermore, Tulp’s specimen was known to have originated in Angola. Although no bonobos live there today, Angola is south of the Zaire River. This immense, at times more than one-kilometer-wide water barrier currently fully separates chimpanzees, to the north, east, and west,




Yerkes greatly admired his bonobo’s character and intelligence, writing: “I have never met an animal the equal of Prince Chim in approach to physical perfection, alertness, adaptability, and agreeableness of disposition.” Much has been made of this opinion of one of the greatest authorities on ape psychology. Before accepting Yerkes’s enthusiasm for Chim as a blanket statement about the species, however, we should realize that the scientist seriously underestimated his subject’s age. The slight build of the bonobo led him to believe that Chim was only three years old, whereas a postmortem inspection by Coolidge indicated an age closer to six. In the same way that a child twice the age of another is mentally far ahead, Chim may have come across as brilliant compared to the chimpanzee, Panzee, with whom he was raised. Moreover, Panzee suffered from tuberculosis, another serious disadvantage compared to the healthy Chim. Yerkes himself fully realized the limitations of his comparison, stating that intelligence, temperament, and character very much depend on physical constitution of the animal. Unfortunately, these reservations are rarely mentioned when Yerkes’s high regard for Chim is cited in support of claims that bonobos are extraordinarily intelligent. There is no doubt in my mind that they are, but whether their intelligence exceeds that of other apes remains an open question. Simian IQs are about as contentious an issue as human IQs. For one thing, there is great individual variability: comparing a few bonobos with a few chimpanzees is not going to tell us much. I know some exceptionally bright anthropoids, but certainly not all of them are bonobos. At this point it is not at all clear in which cognitive areas, if any, the bonobo systematically outshines other apes. The first study of substance comparing bonobos and chimpanzees was carried out in the 1930s at the Hellabrunn Zoo in Munich. It took Eduard Tratz and Heinz Heck until after World War II to publish their findings, based on an inspection of the preserved bodies of three apes Kanzi the talking ape. A portrait of Kanzi, the bonobo that would and film footage collected during their help teach other apes how to understand english.



Bonobo mothers have a simliar relationship with their children as human mothers do. They are very caring of their children and will spend much of their time with it.

lives: terrified by the city’s bombardment during the war, all three bonobos had died of heart failure. Tratz and Heck’s eight-point list of behavioral differences between the two Pan species still stands as the first outline of the areas of greatest contrast: sexual behavior, intensity of aggression, and vocal expression of the bonobo.

exchange in a group of bonobos than in a group of chimpanzees. Chimpanzees call when seriously alarmed, aroused by food, or in order to intimidate one another. Few animals can produce the din characteristic of chimpanzees, but much of it occurs on wellcircumscribed occasions.

Given what we know now, points 1 through 4 are undoubtedly correct. Even though the difference in aggressivity is one of degree only, it cannot be denied that the treatment to which chimpanzees occasionally subject one another, including biting and full-force hitting, is rare among bonobos. Chimpanzees also erect their hair at the slightest provocation, pick up a branch, and challenge and intimidate anyone perceived as weaker than themselves: they are very much into status. By bonobo standards, the chimpanzee is a wild and untamed beast, or as Tratz and Heck put it: “The bonobo is an extraordinarily sensitive, gentle creature, far removed from the demoniacal primitive force [Urkraft] of the adult chimpanzee.”

The final point concerns sexuality. Because Tratz and Heck wrote before the sexual revolution, they felt the need to wrap their shocking findings in Latin. In those days, face-to-face copulation was regarded as uniquely human; a cultural innovation reflecting the dignity and sensibility separating the human race from “lower” life forms. The two zoologists claimed, however, that whereas chimpanzees mate like dogs (more canum), bonobos follow the human pattern (more hominum). They added the important observation that the genitals of female bonobos seem adapted to this position: the vulva is situated between their legs rather than oriented to the back, as is the case in chimpanzees.

As regards point 5, Blanche Learned’s pioneer (albeit unwitting) comparison of vocal repertoires is worth noting. Before the species difference was established, she listened with a musical ear to Yerkes’s two apes, Chim and Panzee. According to my calculations from Learned’s phonetic transcriptions of hundreds of vocalizations, Chim mostly uttered a (48%), ae (38%), and oo (10%) sounds, whereas Panzee mostly uttered oo (68%), o (12%), and oa (7%) sounds. There is indeed no quicker way to distinguish the two ape species than by their voices. When Heck, who was the director of Hellabrunn Zoo, first heard bonobo calls coming out of a cloth-covered crate, he was convinced that he had received the wrong animals. Their calls are so high-pitched and penetrating that they do not even remind one of the typical drawn-out “huu ... huu” hooting of the chimpanzee. The difference in timbre between the voices of the two species may well be of the same magnitude as that between a small child and a grown man.

To this day, both academic and popular writers perpetuate ridiculous claims about human mating patterns, penis size, and general sexiness. The primary reason for overlooking the considerable early knowledge about bonobos must have been that most of it was unavailable in English. Who browses through journals such as Saugetierkundliche Mitteilungen? Apart from their role in the naming game (they were the first to propose “bonobo”), Tratz and Heck were ignored and forgotten by the scientific community. Another overlooked work is an admirably detailed investigation at three European zoos by Claudia Jordan, whose 1977 dissertation, “Das Verhalten zoolebender Zwergschimpansen” (The Behavior of Zoo-living Pygmy Chimpanzees), contains virtually all of the basic behavioral information presented as new discoveries in the literature of a second reason that little attention was paid to some of the early studies was the tendency to dismiss unusual behavior in zoo animals as artifacts of captivity. Could it be that bonobos act so grotesquely because they are bored to death, or under human influence? We know now that, except under extreme conditions, the effects of captivity on behavior are less dramatic than used to be assumed. Whatever the conditions under which other primates are kept, they never act like bonobos. In other words, it must be something in the species, rather than in the environment,

It is also true that bonobos tend to gesticulate when calling, and that vocal activity among them is high. Bonobos are excitable creatures who frequently “comment” on minor events around them through high-pitched peeps and barks. Even if most of these vocalizations are noticeable only at close range, one definitely hears more vocal



that produces the bonobo’s characteristic behavior. It was only when fieldwork got off the ground, however, that the behavior-as-artifact explanation could be put to rest. Research in the bonobo’s natural habitat validated rather than contradicted the pioneering observations of Yerkes, Tratz and Heck, Learned, Jordan, and others. In 1974, Alison and Noel Badrian, a young couple of Irish and South African extraction, bravely entered the remote jungles of northern Zaire on their own, without financial backing. They established a study site in Lomako Forest, which is still in use today, although observation has been discontinuous and conducted by a number of different scientists. The other main study site in Zaire, established in the same year, has known much greater continuity and has, as a result, become the dominant source of information about wild bonobos. This site, named Wamba, was founded by Takayoshi Kano of Kyoto University, in Japan, after a five-month survey of the distribution of Zaire’s bonobo population. Transportation by other means being virtually impossible in this region, Kano traveled enormous distances on foot and by bicycle. These and other dedicated fieldworkers have advanced our knowledge of bonobo behavior by giant strides, confirming the significance and richness of these apes’ sexual behavior and putting their social organization in the context of the ecological background to which it is adapted: the swampy rain forest covering the flat basin of the Zaire River. Because wild bonobos are extremely shy, it takes a long time to habituate them to human presence. At Wamba, this problem was solved by a technique widely employed with Japanese macaques in the investigators’ home country: food provisioning. By planting a few hectares of sugarcane near their range, Kano was able to entice bonobos out of the forest. At Lomako, such techniques have never been employed. The Lomako site has therefore something unique to offer: a look at the ranging and foraging patterns of bonobos undisturbed by human provisioning.Despite the establishment of Wamba, Lomako, and a handful of other field sites, bonobo research still lags far behind that on chimpanzees in both scope and intensity. Over recent years, however, interest has grown rapidly, not least A side by side comparrison of a chimpanzee and a bonobo ape. The bonobo (left) has smaller because bonobos seem to present a ears. The chimpanzee (right) has a brow that protrudes out more and more facial hair. mirror-image of the traditional pic-



ture of our primate relatives as to male-dominated and violent. As a feminist needs a journalist for a nature magazine once put it to me: “Bonobos are our only hope!â€? An ideological interest in the species may not sound desirable to most scientists, yet so long as it leads to scholarly, honest, and rigorous study, I do not see much wrong with it. As a result of continued research, current impressions and theories will either be confirmed or require revision, and we shall gain a deeper understanding of why bonobos evolved the sort of society that they live in. In the meantime, captive bonobos have become more attractive for behavioral studies: zoo colonies now include more individuals in more naturalistic enclosures than the single individuals or small groups of the past. In addition, the apes live longer than before. Bonobos are extremely susceptible to respiratory disease: they used to survive only a couple of years in captivity. With greater care and better nutrition, there now are bonobos aged twenty, thirty, or older in zoos and research institutions. The development towards improved survival and larger social groupings began at the San Diego Zoo, where I conducted my own research. This zoo started out very modestly, in the early 1960s, with a single pair of bonobos: Kakowet and Linda. These two were so prolific that they produced the greatest number of children and grandchildren known of any bonobo couple, captive or wild, in the world. Part of the reason was what know enough to drag the bonobo out of the obscure corner in which primate specialists have been debating its peculiarities among themselves. Its behavior is bound to overthrow a number of cherished assumptions about the course of human evolution. In addition, the species is fascinating in itself; it fully deserves a place in the public mind alongside our better-known ape relations. ÂŤ


FRANSISCUS (FRANS) DE WAAL phd (born 29 October 1948, ‘s-Hertogenbosch), is a Dutch primatologist and ethologist. He is the Charles Howard Candler professor of Primate Behavior in the Emory University psychology department in Atlanta, Georgia, and director of the Living Links Center at the Yerkes National Primate Research Center and author of numerous books including Chimpanzee Politics and Our Inner Ape. His research centers on primate social behavior, including conflict resolution, cooperation, inequity aversion, and food-sharing. He is a Member of the United States National Academy of Sciences and the Royal Netherlands Academy of Sciences. IRA FALTOW npr science correspondent and award-winning TV journalist Ira Flatow is the host of Talk Of The Nation: Science Friday. He anchors the show each Friday, bringing listeners a lively, informative discussion on science, technology, health, space and the environment. Flatow is also founder and president of TalkingScience, a 501 non-profit company dedicated to creating radio, TV and Internet projects that make science user friendly.

BIBLIOGRAPHY ADAMS, S., E. MUCHMORE, J. RICHARDSON. 1995. Bio safety. In: BENNETT, T., C. ABEE, R. HENRICKSON (EDS). Nonhuman Primates in Biomedical Research: Biology and Management. San Diego: Academic Press. p. 377-420. CRAMER, D. AND A. ZIHLMAN 1978. Sexual dimorphism in the pygmy chimpanzee Pan paniscus, In: Chivers, D. K. Joysey (eds) Recent Advances in Primatology. Volume 3: Evolution. Academic Press London. pp. 487-490. DUPAIN, J. AND L. VAN ELSACKER 2001. Status of the proposed Lomako Forest bonobo reserve: a case study of the bushmeat trade. In: All Apes Great and Small, Volume I: African Apes. Kluwer Academic/Plenum Publishers, NY, Boston, Dordrecht, Ondon, Moscow. pp. 259-273. ENOMOTO, T. 1990. Social play and sexual behavior of the Bonobo (Pan paniscus) with special reference to flexibility. Primates 31(4): 469-480. FURUICHI, T. AND C. HASHIMOTO 2004. Sex differences in copulation attempts in wild bonobos at Wamba. Primates 45(1): 59-62. FURUICHI, T. AND J. THOMPSON (Eds) 2008. The Bonobos: Behavior, Ecology, and Conservation. Springer Science + Business Media, LLC, New York IDANI, G. 1995. Function of peering behavior among bonobos (Pan paniscus) at Wamba, Zaire. Primates, 36(3): 377-383. JURKE, M., L. HAGEY, N. CZEKALA, N. HARVEY 2008. Metabolites of ovarian hormones and behavioral correlates in captive female bonobos (Pan paniscus). KANO, T. 1992. The Last Ape: Pygmy Chimpanzee Behavior and Ecology. Stanford University Press, Stanford, California. ZIHLMANN, A. L. 1984. Body build and tissue composition in Pan paniscus and Pan troglodytes, with comparison to other hominoids. In: Susman, R. (Ed.) The Pygmy Chimpanzee: Evolutionary Biology and Behavior, Plenum Press, New York and London. pp. 179-199.

Bonobo: The Forgotten Ape  

Essay and Interview on Bonobos

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