Whether from hubris or insecurity, humans like to view our species as the crown of creation, beings beyond compare in the animal kingdom, as if our advanced cognitive and behavioral skills appeared de novo with the emergence of the Homo lineage. Few have done more to demonstrate the folly of such an anthropocentric view than Frans de Waal.
For nearly 40 years, de Waal has studied the evolutionary origins of social intelligence in primates, from capuchin monkeys to chimpanzees, eviscerating the notion that only humans are capable of empathy, emotions, altruism, and morality, and of transmitting social mores and culture. Likewise, he argues, we can’t blame nature “red in tooth and claw” for our history of violence, warfare, and male dominance.
A lifelong student of animal behavior, de Waal is C.H. Candler Professor of Psychology and director of the Living Links Center for the Advanced Study of Ape and Human Evolution at the Yerkes National Primate Research Center at Emory University. He started studying chimpanzees in 1975, and was the first to show that chimpanzees engage in coalition “politics” and practice reconciliation and conflict resolution. De Waal has explored the evidence and implications of other species’ cognitive capacities in nine books, including The Age of Empathy, which incorporates his most recent work on the evolutionary origins of morality, empathy, and emotions.
In a new article published in PLoS Biology, “Research Chimpanzees May Get a Break,” de Waal considers a recent Institute of Medicine report, commissioned by the National Institutes of Health to evaluate the scientific need for using chimpanzees in biomedical research. Given what we know about the cognitive, social, emotional, and cultural attributes of chimpanzees, de Waal argues, the question is fundamentally an ethical one. And for de Waal, the answer is clear: the sort of experiments that can ethically be done on human volunteers are okay to do on chimpanzees.
I spoke with him in Vancouver at AAAS, the annual meeting of the American Association for the Advancement of Science, after his plenary talk, “Good Natured: From Primate Social Instincts to Morality.”
Gross: Your research has repeatedly drawn parallels between nonhuman primate and human cognition and behavior. In explaining your research focus, you’ve said, “For me, there is nothing more logical than to look at human society through the lens of animal behavior.” What can animal behavior tell us about human behavior?
De Waal: I’ve always looked at humans as animals and I’ve always looked at animals as having emotions and so on, and sharing cognition with humans. So for me it’s really not a contradiction. People often say, “Well, we are not animals.” That’s not something that a biologist understands actually. If we’re not animals what are we? We’re certainly not plants.
Gross: What would you say to those who argue that there are huge gaps in cognition between monkeys and apes and humans?
De Waal: Over the years the dividing line between humans, certainly between humans and the apes, has sort of become fuzzy under the influence of field work, such as the work by Jane Goodall, Toshisada Nishida, and others, and under the influence of experimental work on cognition, which has shown all sorts of capacities that we had not suspected in the apes.
Also, neuroscience has not really helped maintain the dividing line because the brain of a human doesn’t contain any parts that the brain of an ape doesn’t have. The human brain is much bigger than, let’s say, the chimpanzee brain. It’s three times bigger. But there’s nothing in there as far as we can tell that is not in a chimpanzee brain. At the microscopic level there are a few differences and they’re probably interesting, but you would think if humans are so dramatically different, as different as the philosophers have often assumed, that you would find something in the human brain that is absolutely unique and that you would say, “Well, there’s a part there that no one else has,” but we have never found it.
Gross: What are some of the seminal experiments that revealed similarities in cognitive or behavioral traits between apes and humans, suggesting we’re not in fact unique, as many like to think?
De Waal: There are many. For example, tool use used to be considered uniquely human. And then when it was found in captivity by Köhler, this is in the 1920s, people would say, “Well, but at least in the wild they never do it.” And then it was found in the wild, and then they would say, “Well, at least they don’t make tools.” And then it was found that they actually also make tools.
So tool use was one of those dividing lines. Mirror self-recognition is a key experiment that was first conducted on the apes. The language experiments, even though we now doubt what the apes do is actually what we would call “language,” they certainly put a dent in that whole claim that symbolic communication is uniquely human.
My own studies on, let’s call it “politics,” and reconciliation behavior and pro-social behavior have put a dent in things. And so I think over the years every postulate of difference between humans and apes has been at least questioned, if not knocked over. As a result, we are now in a situation that most of the differences are considered gradual rather than qualitative.
And the same is true, let’s say, between a chimp and a monkey. There are many differences between chimps and monkeys in cognitive capacities, but we consider them mostly gradual differences.
The more we look at it, even if you take the difference between, let’s say, a human and a snake or a fish, yes, between those species the differences are very radical and huge, but even these species rely on some of the learning processes and reactions that we also know of in humans.
Gross: In your PLoS Biology commentary, you note that the Institute of Medicine committee lacked expertise in key areas. What was the biggest oversight, in your opinion?
De Waal: The NIH made the curious request that ethics was going to be kept out of the discussion, which is strange since the whole reason we are discussing chimpanzees and not rats or mice is the ethical issue of why would we use the chimpanzee, which is a close [human] relative and shows so many emotions and cognitions that humans have as well. Is it justified to use chimpanzees?
To try to keep the ethics question out was, I think, a misjudgment on the part of NIH. But the IOM then put a bioethicist in charge so their response was more or less we cannot keep ethics out, let’s talk about it.
The report is very interesting because it was written by people who are not experts in chimpanzees but who listened to many experts, so they had hearings at which we spoke, for example. They were open about that and talked with us, and the resulting report is actually quite balanced.
The report basically argues that except maybe for one exception there is no urgent reason to keep using chimpanzees for biomedical studies. Their main conclusion is that the justification to keep using chimpanzees for this purpose is actually not that strong.
Gross: Yet they’ve left the door open to continue some research.
De Waal: Yes, they have left the door open for prophylactic hepatitis C vaccine testing. Normally that kind of testing would require large numbers because you want statistical power. Now, the NIH owns less than 1,000 chimps, which can certainly not all be used for that kind of testing, so we’re talking about a small sample of a couple of hundred that could potentially be used, which is not sufficient to do anything dramatic. So I don’t see it as a viable option. They have mentioned that that’s the one area in which chimps could still be extremely useful. But I’m not sure we can fill this particular need at this point.
Gross: What if there were sufficient numbers of chimps to provide the appropriate statistical power?
De Waal: Even if we had the numbers I would have questions like, Is this the best use for an animal that we consider ethically problematic to be used, because you’re going to be virally infecting them, which is something that I would want to avoid at this point. Rodent models are coming up very fast, and are likely to take the place of the apes. So even if we had the numbers, I’m questioning whether we should be doing it and whether we haven’t reached the point now in the discussion where we say let’s draw a line and say it’s over as far as chimps are concerned for biomedical research.
Gross: What in your view is the most compelling reason to stop invasive research on chimpanzees?
De Waal: The most compelling reason would be an ethical one. I myself have never done any invasive studies in chimps for exactly that reason. I don’t want to do that kind of thing on the chimpanzee because they are so mentally and psychologically close to us. Most people of my generation and younger who work with this species share this feeling. It’s almost like you’re working with humans, you know, they are very closely related to us.
It’s very easy to extend the moral qualms we would have with experiments on humans to chimpanzees. It’s much easier to extend them to chimpanzees than to, let’s say, rats or mice which are so much more distant from us.
Gross: What criteria should we use to decide what type of research on chimpanzees would be morally acceptable?
De Waal: I think we should keep doing non-invasive studies on chimpanzees, such as behavioral studies or comparative genomics, maybe non-invasive neuroscience. It’s hard to do the same imaging studies as we do on humans at the moment, but it’s going to happen, I think, one day.
For me, non-invasive would be defined as research that I would not mind doing on a human. And it does require a different mindset at NIH and maybe other funding agencies because sometimes if you submit proposals to them that include chimpanzees, they still will argue, “Well, you’re using animals, why don’t you go into the brain and manipulate it this way or that to enhance your study?”
The science community needs to change that mindset and treat chimpanzee studies basically the way they treat human studies. There’s a lot of things we cannot do on humans, and that we will not do on humans, and that will be the situation for chimpanzee research, I think, where we say, “Well, we can do all the same things that we do on humans, but that’s about it.”
Gross: In your commentary, you point out that the United States shares the distinction with Gabon of being the only nations in the world to hold chimpanzees in biomedical facilities. That’s surprising.
De Waal: The movement to remove chimpanzees out of research laboratories started to get teeth about ten years ago. The movement existed probably earlier but at least ten years ago certain countries like Japan and the Netherlands had chimpanzees in labs and said they stopped this kind of research for ethical reasons, it was very explicitly for ethical reasons.
And I think the U.S. is going to join the other countries, maybe not today, maybe not tomorrow, but it will happen because the whole trajectory – and that’s what’s pointed out in the IOM report – is in this direction. And my argument is why not get ahead of that trajectory, and why not do it now rather than wait a couple of years.
Gross: What should be done with chimpanzees that would be retired?
De Waal: There is a bit of a desire on the part of existing facilities to keep the chimpanzees there and turn the facilities into sanctuaries. But actually most existing research facilities are not particularly suited for that, because they were built for research, for shifting chimpanzees around, for having them in small groups so that you could easily work with them. They’re not optimal facilities for keeping them around. Whereas there are certain sanctuaries that have a lot of space, that have forests available for them, and I think that’s the way we should retire them. We should retire them in large social groups and hopefully still in environments in which some limited, non-invasive studies, like behavioral studies, can still be done.
I think the whole retirement issue needs to be rethought. Some money will need to be put into it. This cannot be done on the cheap, and if you look at the Netherlands and Japan, they invested quite large sums of money in the retirement of research chimpanzees.
Gross: You recently wrote a commentary called What Is an Animal Emotion?, a subject that was long considered off limits for study. Why has there been such resistance to studying emotions?
De Waal: The view of emotions in the field of animal behavior has been quite negative under the influence of the behaviorists. Skinner would say that if animals have emotions – he would put “emotions” always in quotation marks because he really didn’t believe in them – but if they have them, they’re largely irrelevant and have nothing to do with behavior.
So the view used to be very negative. And then, of course, with the cognitive revolution human emotions became a major issue. Human emotions were recognized, but the behaviorists kept a taboo on animal emotions.
That is completely changing. Not so much under the influence of behavioral scientists such as myself, even though we do our best, it has changed mostly under the influence of neuroscience. If neuroscientists test fear in humans, they see that it activates the amygdala in the brain, then they take rats and they stimulate the amygdala and they get fear responses, and they say, “Well, if the same part of the brain is involved in the same sort of responses, we should use the same terminology for the two responses so we’re going to call it fear in humans as well as in rats.”
And so the neuroscientists are much less reluctant to talk about fear, aggression, love even, affection – they use all these emotional terms because they see the correspondence between what happens in the monkey brain or the rat brain and the human brain.
As a result, the taboo on animal emotions is crumbling very rapidly and I think the behavioral scientists who are still reluctant, they need to catch up with what is happening. My feeling has always been that it’s very hard to find an emotion that humans have that a chimpanzee cannot have.
I sometimes think of guilt and shame as the only ones that are maybe left. But even for those I could make the argument that they are not as uniquely human as we often think.
But all the rest, definitely, like jealousy and affection and anger, all these kind of emotions, the physiological and behavioral signs are there and increasingly also the neurological signs, so I see no reason to keep that completely separate between human and animal.
Gross: Do you see any applications for our current understanding of this cognition continuum for animals? Are there any policy recommendations aside from the Institute of Medicine report on chimpanzees that you can see coming out of our deeper appreciation of animal capacities in cognition and behavior?
De Waal: I’m not sure that what happened with chimps is going to happen to all species because people don’t worry much about rodents. For example, when we have rodents in the home we try to get rid of them, and so I’m not sure that people are going to apply the same concern that they have for chimps or elephants to other animals.
But I do feel there is a general trend in society, in the public, and scientists need to pay attention to that, of taking animals more seriously than we used to.
And this may also have an effect in the agricultural industry, on how we treat agricultural animals, which is a much larger number than research animals, actually, and so it may have effects everywhere, effects on the ethics of how we treat animals, and this will probably also affect the biomedical community.
It doesn’t mean that we will stop doing what we’re doing but we may start doing it differently. That’s my understanding of the movement, that we will increasingly think twice before we do certain procedures on animals.
Gross: Is there anything else you’d like to say about the IOM report?
De Waal: I found the report to be quite solid. It was well-written and balanced and I was also glad to see that the NIH took it seriously. They immediately put a stop on all the research to reflect on their position. I don’t know what the outcome of their deliberations is going to be, but their reaction was a sign of the times, because society is taking the issue increasingly seriously.
Liza Gross is Senior Science Writer/Editor for PLoS Biology. You can find her on Twitter as @lizabio (views her own!).