“One Could Describe Us as Chimpanzee Ethnographers”

The Text will be published in the catalogue of the exhibition:
Ape Culture, edited by Anselm Franke and Hila Peleg,
Spector Books / ISBN 978-3-95905-006-7 (eng.)

Cord Riechelmann: Professor Boesch, when you became well known beyond the field of primatology with the publication of your first studies on the nut-cracking chimpanzees of Taï National Park, in Côte d’Ivoire, you were venturing into a highly specialized field: the use of tools by nonhuman individuals. Although there had previously been accounts by Jane Goodall and others, your work added a totally new dimension: The chimpanzees used certain types of “anvils” and hammers and, furthermore, you found something resembling workshops to which the animals would return to crack the nuts. Can you describe the route you have taken to this field of primatology, namely the sophisticated use of tools?

Christophe Boesch: My personal experience with primatology started in 1973, with Dian Fossey and the mountain gorillas of Rwanda. I was participating in a longitudinal project that had been launched to count the gorillas in the Virunga Mountains. In common with many young people, I harbored a fascination for gorillas, and because I’m French Dian Fossey accepted me onto her team. This was useful in our dealings with the Rwandan authorities, whose official languages also include French. I was able to gain a lot of experience that subsequently proved valuable in my own project.

I had learned from my professor in Paris that chimpanzees in West Africa, in Côte d’Ivoire, were able to crack nuts. However, this had never been observed. There were only two reports that evidence of nut-cracking spots had been found, such as cracked nutshells and hammers—and the Africans who were present confirmed that chimpanzees had been responsible. As a young scientist I thought to myself firstly that as our closest relatives chimpanzees are fascinating, and secondly, their use of tools could also raise significant questions for us humans.

So I decided to take the risk and travel there. And in the seven months I spent in Côte d’Ivoire I was in fact able to observe one female chimpanzee cracking nuts. At first I just heard the noise, but as I approached I saw her. She held a hammer in her hand. This was the first ever confirmation that chimpanzees use a hammer to crack nuts. On the basis of this observation I was able to secure more funding and proceed with my own project. Together with my wife, Hedwige Boesch, I then traveled to Côte d’Ivoire in 1979—and today we are still there continuing our work.

Working with chimpanzees in Africa is difficult because wherever they live they are hunted by humans: Their meat is reputedly very tasty, and because they are our closest relatives there is a belief that chimpanzees possess supernatural powers. Eating their meat is said to have a beneficial impact on children and the sick. This is why chimpanzee bones feature strongly in traditional medicines. And because they are hunted chimpanzees are very shy and run away before you can even glimpse them. It took two years before we were able to make any tangible progress with them. And we needed five years before we were able to observe them properly—that is, observe them despite their being aware of our presence. This length of time was necessary in order to become sufficiently used to each other in the habituation process so that the animals could be observed without them altering their behavior.

CR: If I recall correctly, Jane Goodall also needed five years.

CB: Exactly. She attempted to expedite the process by feeding her chimpanzees with bananas, but it didn’t really help much.

Our biggest stroke of fortune was that the chimpanzees cracked the nuts there. The nut season lasts approximately four months a year. And cracking nuts makes a noise. So although the chimpanzees knew that humans were in close proximity—which they didn't want—they would always betray their presence by the noise they made when striking nuts. We developed a good ear for this specific sound and increasingly were able to locate the chimpanzees. The initial analyses sought to determine how many nuts the animals cracked a minute, how many hammer blows they needed, and who opened the nuts. We eventually concluded that the females were more efficient than the males—which contradicted the general tendency of our science to focus on the males.

CR: I noticed that at the time. Your initial studies were an effective and well-substantiated refutation of everything that devolved from the “man the hunter” hypothesis on active hunting males and passive females.

CB: Exactly. And the feminists, who were very active at the time, immediately cited my works to support their case—as proof that in our evolutionary history females played a much more important role than had hitherto been ascribed to them.

Our question, however, centered on the extent to which this behavior is common throughout Africa. To our astonishment we discovered that there is a boundary in Côte d’Ivoire that runs along the Sassandra River. All chimpanzees west of the river cracked nuts, while all chimpanzees to the east of it didn't. Despite the fact that east of the river there were just as many nut trees, just as many roots to use as anvils, and sufficient material for hammers. Thus there were no environmental factors. Consequently, we proposed interpreting nut-cracking as a cultural behavior since the explanation could only be of a purely social nature. The chimpanzees on the one side did it, but those on the other side did not. It was twenty-four years ago that we published this …

CR: You conducted your research with a fascinating attention to detail, even compiling an encyclopedia of the various sizes and shapes of the hammers. Didn’t your work also demand a comprehensive knowledge of the individuals you observed? Or am I going too far?

CB: Not at all. Our observations of chimpanzees—and this applies generally to primatology—require that we identify the individual animals. And often it took a frustratingly long time until we got a result. Chimpanzees do not attain adulthood until they are thirteen to fifteen years old. That means if you wish to study how a particular behavior is acquired, you should first be aware that you are starting out on a project likely to span at least five to ten years. And that makes things difficult.

CR: It makes things a) difficult and b) doesn’t it also buck the prevailing trend—initiated by scientists themselves—to produce results with ever greater alacrity? Does it perhaps mean that you are one of the last remaining exponents of longitudinal studies?

CB: I wouldn’t say that. Maybe I belong to a generation that structures their studies over a longer period. But I never imagined at the outset that I would end up spending the next thirty-five years working with chimpanzees. In principle, the advantage of longer studies over shorter ones is accepted by scientists. And this also applies to the financial backers, such as the Schweizerischer Nationalfonds, which has always supported me. At the same time, researchers are, of course, continually under pressure to come up with new ideas. That much is obvious. And therefore, after six years of researching nut-cracking, I decided to address another topic: the hunting behavior of chimpanzees.

CR: A term often still used in this context—and I heard it myself in lectures—is “predatory hate.”* And Jane Goodall observed that hunting and catching the colobus monkey was a purely male activity among chimpanzees. Yet in your work neither hate and aggression, nor this male aspect are afforded any special emphasis.

CR: Absolutely. I don't think that this concept of hatred can be applied to chimpanzees. For many predators, hunting is simply a means to acquire nourishment, and is not motivated by hate or other similar emotions. This would unnecessarily complicate matters for the hunters since a hunt requires a certain amount of planning. They are searching for their prey, or perhaps they first search for hunt participants and subsequently the prey—although success is not always guaranteed. This means they must be able to judge when it is worthwhile to hunt and when not. Furthermore, chimpanzees hunting in groups must also be able to organize the pursuit: Who assumes which role? How can I help the others to stop that colobus escaping? If hunting were purely driven by emotion, everyone would simply charge at the intended prey, probably without ever catching anything.

Chimpanzees hunt smaller apes that live high up in the trees and are thus able to choose escape routes the chimpanzees cannot follow. Hence, if the chimpanzees didn’t organize themselves, they wouldn’t be successful in such forests. This explains why Taï chimpanzees hunt in groups far more commonly than the chimpanzees of other forests, where it is easier to corner their prey.

CR: The chimpanzees’ hunting behavior in the difficult conditions of the Taï rainforest serves as a prime illustration of what you describe as ecocultural; I found that especially convincing, for example, in the demands placed by the specific ecological conditions on the learning process.

CB: You could also describe us as chimpanzee ethnographers. I have always attached great importance to showing that chimpanzees display highly variable and flexible behavior and that each population can develop quite different behavioral patterns. This is something that must be taken into consideration. And their behavior is partly shaped by environmental influences, which in the Taï forest implies dense, tropical rainforest. Contrast this to the open bush country in Gombe, Tanzania, where Jane Goodall worked; this was savanna mixed with forest, where the visibility and topography, in other words the trees and the structure of the forest, are very different. Consequently, chimpanzees—in common with many other species—can also be expected to adapt to the ecological conditions. And this brings us back to our definition of culture, because we presume that chimpanzees, too, will adapt to the conditions of their particular habitats in the evolutionary process.

That a species can display very different behavioral patterns in very different habitats has nothing to do with culture. It’s merely an adaptation to the environment. Given that we were endeavoring to provide a means of opening the concept of culture to animals, we felt an obligation to prove that cultural differences between individual populations were not dependent upon environmental conditions—even though we know that culture in human beings is also dependent upon the environment. The definition of culture we applied at the outset in order to demonstrate culture in animals was therefore narrower than the criteria applied to humans. This, of course, is not really fair …

CR: I regard that as a very important aspect of your work. Michel Foucault once remarked that when he worked with outsiders, for example mental patients, he had to be more precise than with normal, healthy people. I’m not, of course, comparing chimpanzees with the mentally ill. I do, however, regard it as the fairest solution for chimpanzees if we apply more rigorous criteria.

CB: It is simply more difficult because there are always two camps within scientific discourse. And among those working with chimpanzees, there are perhaps even more camps because we are running up against the famous major barrier or the “golden barrier” as Stephen Jay Gould dubbed it, which distinguished or is intended to distinguish man from all other living creatures. Of course, this is my motivation for working with chimpanzees. Like all chimpanzee researchers I am keen to ascertain how high this barrier really is. In many ways it was set by religion, subsequently by scientists and philosophers. Socrates, Rousseau, and the rest had no idea what these animals do or are capable of. All they had were travelogues or illustrations of individual animals, randomly observed—and frequently the animals were already dead. There was no conception of great apes in their natural environment, a scientific myopia that lasted until the early 1960s. This was the point at which Jane Goodall and other biologists and behavioral ecologists went out into the wild and observed the animals in their natural habitats.

The upshot is that today we have the incredible luxury of being able to conduct scientific research into the issue of the “golden barrier.” I am a little shocked every time I see that the pleasure in testing these barriers is not shared by many scientists. Which once more brings us back to the issue of culture …

Culture is a term conceived by humans for humans in order to represent the greatest achievement of humanity. However, when we speak of culture in animals it is clear that the skeptics standing on the other side of the barrier perceive everything very critically. And the problem of furnishing evidence of culture with nut-cracking is that on the one hand, there are populations that crack nuts, and on the other, populations that do NOT crack nuts. It is very difficult to prove why one population or animal does not do it.

One advantage of our project with Taï chimpanzees, however, is that we started quite early in getting neighboring groups habituated to human observers. Accordingly, over the years we were able to monitor three neighboring groups and examine the cultural differences between them. During the nut-cracking season, we observed that each of these groups have specific criteria for selecting a good hammer: The three groups that regularly engage in aggressive contact and probably exchange females each have clearly distinguishable preferences in the hammers they use.

Thus we have three neighboring groups in regular contact within the same forest. Despite this, however, clear cultural differences remain in regards to the criteria applied to choose their hammers. This is quite strange because females regularly migrate from one group to another**. This shows that the females adopt the habits of their new group: They migrate out when they are between ten and twelve years old, an age at which they are already highly proficient nutcrackers, so although they have mastered the technique of their birth group, they always apply the techniques of the new group they join.

CR: So given that the ecological conditions are identical, this is no longer ecocultural, but purely cultural, as it were?

CB: It’s genuine proof of cultural behavior.

CR: I would now like to address two issues that, whilst also pertaining to culture, are not related directly to chimpanzees. Firstly, have you always managed to come to an agreement with the governments as far as research permits are concerned?

CB: Yes always. Fortunately.

CR: And secondly, has the forest changed over the years?

CB: Over the past thirty-five years deforestation in Côte d’Ivoire has progressed so swiftly that virgin forest can only be found in the National Park. While this is very sad, it is also unsurprising given that humans have never shown any respect for the environment. We have destroyed everything and as a consequence, average rainfall in Africa over the past sixty years has fallen both drastically and continually. This has triggered increasing desertification in a southerly direction; so what are people supposed to do? Because they can no longer farm the land, they also migrate southwards. Coastal populations have trebled, and over half of the migrants are from the north. It is obvious that this development is detrimental to the forests. The destruction of the forests is only exacerbating the problem of drought in Africa. Rainfall in Côte d’Ivoire, for example, has declined and dry periods are even being recorded along the coast—something that is unprecedented. What we are experiencing in Africa and on other continents is a consequence of climate change. As a result the animals that once lived in these forests are no longer present. And along with the forests, the elephants, chimpanzees, and forest antelopes have also disappeared.

CR: In view of the essentially hopeless situation of your chimpanzees, can I ask how you manage to continue to work so enthusiastically, not only in Côte d’Ivoire, but also with your Pan African Programme: The Cultured Chimpanzee, which you launched to survey and research all the populations still in existence?

CB: You can only work for chimpanzee protection if you’re—let’s say—an incorrigible optimist. There are unfortunately abundant reasons for growing frustrated, but expressing this publicly is not advisable as it merely makes the job of selling environmental protection even more difficult. But it’s the truth. I think you just have to deal with it, and refrain from constantly peddling illusions.

CR: Although you’ve answered my question fully, I would still like to inquire again how you manage to maintain this—from my perspective—wonderful attitude in which you as a scientist see no alternative but to keep on researching?

CB: I can well understand it if those conducting research into wild populations become so depressed about their animals vanishing that they feel they can no longer continue. An alternative strategy is to become proactive in protecting the environment. This trend can clearly be observed among many primatologists.

CR: Your commitment has always made eminent sense to me by virtue of your uncompromising insistence on distinguishing between wild populations and others, for example, those in zoos. If I understand you correctly, you even claim that comparisons are simply not feasible.

CB: As I mentioned already, I attach great importance to behavioral flexibility among highly developed animals. And not just among chimpanzees. I myself have observed chimpanzees for months on end at various locations and experienced at first hand how strong the differences are between populations, and how great the environmental influence is. I am, of course, observing the animals in their natural habitat. In contrast, when I see animals in zoos or cages I know that these are totally artificial living conditions. The animals are flexible enough to adapt to them—not necessarily to their benefit, but adapt they do. I am convinced that animals raised and living in such artificial conditions are disadvantaged. Captivity means a completely passive environment, where nothing happens. Compared to animals living in the wild, therefore, they are in a much poorer position. This is an idea I have repeatedly pointed out over the years, but fortunately it has been gaining ever more acceptance recently. Studies have now been published that specifically observe the impact these artificial living conditions have on behavior and even more strongly on the development of the brain. From this one can only conclude that captivity is detrimental to the animals’ development. Nevertheless, I am not advocating that we stop working with animals in captivity altogether, as there are certainly a number of things that can be researched there. However, one cannot generalize the knowledge acquired in captivity and apply it to wild animals. The problem is one of interpretation and generalization.

* The term was coined by Irenäus Eibl-Eibesfeldt, a student of Konrad Lorenz.

** Chimpanzees live in groups in which the males always remain in their birth groups, whereas the females migrate out and join other groups when they reach the age of sexual maturity.

Christophe Boesch is the director of the Department of Primatology at the Max Planck Institute for Evolutionary Anthropology in Leipzig. Since 1976 he has studied groups of chimpanzees living in the wild, for example in Taï National Park in Côte d'Ivoire, to examine their behavior in their natural habitat – in particular social learning processes and differences between different populations, for example in the use of tools. In the face of increasing threats to chimpanzees caused by the destruction of the rainforests, in 2000 Boesch established the Wild Chimpanzee Foundation, which is dedicated to protecting their habitats. Together with Hjalmar Kühl he directs the Pan African Programme: The Cultured Chimpanzee, which records the behaviors and habitats of forty different chimpanzee populations in more than twelve African countries.