2018-19 CASBS fellow Elizabeth Lonsdorf, a primatologist at Franklin and Marshall College, discusses the state of wild chimpanzee research and the question of whether chimps have a concept of death.
Elizabeth Lonsdorf at National Geographic
Jane Goodall Institute's Gombe Stream Research Center
International Primatological Society
"Chimps Know Dead When They See It" Discover Magazine
"Chimps Filmed Grieving for Dead Friend" BBC
"Chimps Mourn Nine-Year-Old's Death?" National Geographic Video
Center for Advanced Study in the Behavioral Sciences
@casbsstanford on twitter
Elizabeth Lonsdorf: I'm Elizabeth Lonsdorf. I'm a professor in psychology and biological foundations of behavior at Franklin Marshall College, and broadly I study chimpanzee childhood.
John Markoff: Welcome to Human Centered, a series of short conversations with researchers at the Center for Advanced Study in the Behavioral Sciences at Stanford University. The Center was founded in 1954 to encourage interdisciplinary research focused on the most pressing societal issues of our time. Each year, a range of scholars, scientists, and government officials come to spend a year studying contemporary societal problems. My name is John Markoff. I'm a science and technology writer and former reporter for The New York Times. In these conversations, we've set out to find interesting projects at the Center that shed new light on the way we think about society. Today I spoke with Elizabeth Wonsdorf. She spends several months each year studying wild chimpanzees at Tanzania's Gombe Stream National Park. We talked about the state of primate research and the current question of whether chimpanzees have their own concept of death. Recently you gave this really interesting seminar presentation and you presented evidence that you'd collected, I guess, by observing chimpanzees over reasonably long period, and then you asked social scientists to interpret it. At least that's what I took away with what was happening.
Elizabeth Lonsdorf: Yes, I was asking them to give me feedback on how I had interpreted it. Okay, okay.
John Markoff: So maybe sketch out what you brought to the CASBS seminar.
Elizabeth Lonsdorf: Mm-hmm. Well, one of the kind of hot topics in animal behavior and animal cognition right now is this question of what other non-human animals understand about death. And of course you can't ask an animal that question because they're non-verbal as far as, I mean, maybe they're talking to each other, but they're non-verbal when it comes to us. So there have been a collection of observations over the past several decades of individuals behaving non-normally towards the corpses of other members of their social group that have died. This has been seen in elephants. It's been seen in many non-human primate species, which are of course the animal most closely related to us, to humans. But it's also been seen in some animals like crows. So it's a diversity of responses shown across the animal kingdom, and people are starting to get very curious and interested about what these responses mean about what non-human animals understand about death. So is it simply, "Oh, this thing has stopped moving, it is no longer relevant," and walk away? Or do they have some sort of understanding of death that is what we would think of as a precursor to our more fully fledged, developed understanding of death as humans?
John Markoff: What is the state of the art in terms of looking at your animal communities and whether they have any culture or language? What is the consensus?
Elizabeth Lonsdorf: So it— Depends on who you ask to define culture. So if you ask a biologist to define culture, they talk about group-specific behavioral norms that are not based on genetics or ecology. Now, why ecology is invoked there, I'm not sure, because ecology is involved in human cultures. But biologists will say that orangutans, bonobos, gorillas, chimpanzees, many of marine mammals have these group-specific behavioral norms that are learned socially rather than being genetically or ecologically based. If you ask more people studying more human-centric cultures, they define culture as inclusive of language, religion, those types of things, which we can't study or prove in animals. So there's, there's It depends on if you're asking a biologist or a cultural anthropologist.
John Markoff: After that hour seminar, it forced me to think. I was trying to think, well, as a human, what's different about dying for me than in what I saw in the things you showed us and described to us? And the one thing I think I didn't see was ritual. The ritual of a human funeral is the one— so if I was an alien and looking from space, did you show us anything ritualistic?
Elizabeth Lonsdorf: No. In chimpanzees, which is the animal I was covering, the data set was on, We don't have anything like a ritualized burial or a standard set of behavior in response to the dead. We don't have that.
John Markoff: Now I did find one— I went and read afterwards— I want to ask you about. And there was this one account, I don't know if you know about this, Geza Teleki.
Elizabeth Lonsdorf: Geza Teleki, yep.
John Markoff: Published the first account in '73 apparently, uh, chimps reacting to an accidental death. He recounted the aftermath. I don't know if you showed us anything like this, but I found it. The 16 group member erupted into raucous calling, slapping and stamping the around tearing and dragging vegetation and throwing large stones. Has that been seen again?
Elizabeth Lonsdorf: Yeah, so what Geza was recounting was the responses of the group members to, I believe it was falling from a tree in that instance. And that was an adult member of the community. And the data that I was presenting and covering was specifically the response to mother chimpanzees who have been seen carrying the corpses of their infants for a very long time after death. And because that's the largest dataset we have, that's the thing that's been seen most frequently, that's where I structured my data analysis because there were just enough cases to analyze. We don't see a lot of cases of responses to adult death because in— there are two things. In the jungle, you don't often find corpses. They decompose or get taken away by other animals very quickly. Chimpanzees have a very fluid social structure, so we're not with every member of the group at every moment, so we don't see an adult death very much. And then also, when an adult chimpanzee becomes ill or injured, they actually seem to avoid their social group so that they don't get, you know, picked on, you know, get— chimps are very dominance motivated, so a sign of weakness is not a good thing to show the group. So individuals that are ill or injured often seem to leave the group, and therefore we don't see their responses to that individual dying. So we have a handful of observations like that of the response of an adult death immediately after it happened, and the responses are really variable.
John Markoff: Are you exploring other abstract concepts like death? What are some other abstractions that we we deal with. Love, I guess, would be a—
Elizabeth Lonsdorf: Yeah, and that we can— I mean, this is one of the only— this is kind of one of several projects that I'm working on right now, and the only one really focused on this as an abstract concept. And it came from my overarching interest, which is on infant development and mother-infant relationships. And so I have a very long-term project looking at kind of all aspects of the mother-infant relationship. What does it mean if your mother's more dominant? What does it mean for you as a growing chimpanzee if you have older siblings. Doesn't matter if those older siblings are male versus female. So what pulled me into this was the accumulated number of observations we have of this infant corpse carrying, and I'm thinking like, "Oh, I might actually be able to make something out of this now. We finally have enough observations." So it's more part of a set of questions to do with this larger project than part of a set of questions dealing with abstraction as a topic of focus. Yeah.
John Markoff: What's your dominant project here at the Center this year? Is it the mother-infant relationship? Is that your—
Elizabeth Lonsdorf: Well, so the mother-infant relationship, that's a big, bold, underline topic area. And I have several kind of sub-projects, analyses going on while I'm here at the Center. Kind of getting towards a fuller understanding of that. So a project that I finished up right before I came here was how older siblings and infants interact and whether there's the expected sex differences that we see based on the human literature that older sisters are more interested in babies than older brothers. So that was something that I was working on right as I came here and has since been published. Right now we're looking on analysis of weaning age variation. So chimpanzees suckle their offspring for anywhere from 3 to 8 years, and there's a huge amount of variation in there. And so we're interested in what predicts that variation. Is it maternal dominance rank? Is it the sex of the offspring? Does it have something to do with whether this is your firstborn or later born? Looking at kind of how chimpanzee mothers balance all the both psychological and physiological demands on their time. Because chimpanzee mothers are the ultimate single mother. There's, there's no help from dads in the case of carrying or feeding offspring. She does it all herself.
John Markoff: What do the dads do?
Elizabeth Lonsdorf: Yeah, it's a good question. Um, so this comes from the fact that chimpanzee mating system is promiscuous. So a female, when she's in estrus, mates with essentially everybody. The alpha male gets first access, but then if he's a more egalitarian guy, like we were talking before, everybody can take a turn. And in a sense, that promiscuity then confuses paternity.
John Markoff: Yeah.
Elizabeth Lonsdorf: So it means that you don't get any help, but in theory it means that any given male in your community is unlikely to commit infanticide against your infant because it could be his. Yeah. Theoretically. So the chimpanzee moms is kind of the ultimate single mom model, because not only do they do everything themselves for this infant, but in chimpanzees, the juvenile, the weaned offspring, actually stick around, you know, 6, 8 years after they've been weaned. So mom usually has multiple kids that she's caring for. So say weaning's around age 4 and a half, she could have a newborn, a 5-year-old, and a 9-year-old all traveling with her the 9-year-old wanting to kind of fledge and start joining the big boys, the juvenile still real uncertain because I've just weaned and I don't know how to do everything I need to do, and then the infant just completely dependent. So really trying to figure out how chimpanzee moms do it.
John Markoff: And I was just thinking about there's another abstract concept of paternity that, I mean, what do the alpha males know about the fact that any, you know, there's a connection between copulation and actually Do they know that?
Elizabeth Lonsdorf: Well, we do. We have done some recent analysis on this mother-infant data set that I've been discussing that suggests that adult male chimpanzees tend to both socialize with the mothers of their particular infant and interact with that infant more than— it's still very small rates, and it's not it couldn't be considered like real nutritional caretaking or anything like that, but they seem to interact more frequently than could be expected with their own offspring.
John Markoff: Which suggests they have gaps?
Elizabeth Lonsdorf: Well—
John Markoff: Perhaps?
Elizabeth Lonsdorf: We don't know the mechanism. I mean, the awareness, the conceptual abstraction of "dad" is different from some sort of physiological process that makes you have an affinity for that. So for example, in rats, Rats recognize their kin by smell, and they are more affiliative to their kin than to their non-kin, just by physiological scent alone. So that's a different question than, is there a concept of parentage that means I actively prioritize this kid over another kid? And that's another project that I've been working on while I've been been at CASBS. So it's kind of like I'm on this kick of looking at all the bad things that could happen to babies. One, they could die, and then how does their mom deal with that? And the other is the flip side, which is the mom dying, and how do orphans cope with that? So we know that essentially pre-weaning orphans typically don't make it because they're still suckling, they're getting the majority of their nutrition from their mom, and no other individual can really replace that. But some do make it, and those individuals tend to be adopted or cared for by someone else. Now there's evolutionary theory and publications from other chimp sites that suggest that if there is a maternal relative in the group, 100% of the time that is who's going to adopt this kid. So an older sister, or an aunt, or somebody in the maternal family grouping takes on looking after this kid. But at our study site, we have cases where that maternal relative is present and somebody else takes care of this kid. So it doesn't just seem to be directly along kin lines. And what I've been trying to suss out is, is there any other predictive things? I mean, we have males that have looked after orphans. But if you look into the paternity, it's not the dad 100% of the time. It is some, but it's not the dad 100% of the time. So I've been on a real detective mission to ask kind of these, these questions that take an accumulation of decades and decades and decades of data because we only have one case every few years. But luckily with our partnership with the Jane Goodall Institute, that accumulated data is available.
John Markoff: How often do you go to the field?
Elizabeth Lonsdorf: At least once a year.
John Markoff: And do you have students, or is there continuous observation?
Elizabeth Lonsdorf: There is. The Jane Goodall Institute has a full-time field staff on the ground in Gombe every day, following chimps every day. Luckily, Jane set us up for some of these questions, and when I talked to her— she was in the field in February when I was there— when I talked to her about, hey, I'm finally pulling together all these cases of carrying their babies, or I'm finally looking at all the orphan— She said, "Oh, wonderful. I've been wondering about that since 1964." Since I, you know, so Jane could almost say herself, "I went out with 6 months of funding and thought that would be it. I never imagined it would be 60 years." But because it has been and because so many other chimp sites have followed that path of doing very long-term observations, we are able to answer these questions that either take a long time because of the accumulation of cases or take a long time because the particular scientific question of interest spans generations. So for example, if you're interested in if a particular dominance rank strategy is better, well, better means fathering more offspring, but so you gotta wait for babies to be born to ask that question and do the genotyping. So luckily, yes, Jane set us up for, for questions that could be asked only after decades of accumulated observations.
John Markoff: I was just wondering, is it all observational? Have you thought about— is there anything you could do experimentally that—
Elizabeth Lonsdorf: Yeah, and that's something that people interested in this area are starting to discuss, is an experimental approach to this. I mean, in the wild, essentially no. You can't address questions like this in the wild. It wouldn't be ethical. You have to wait for the unfortunate incidence of some chimp dying and then hope that you're there to observe. But we do have some interesting tools that could be brought to bear. Most primates can be trained to use, for example, a computer touchscreen and answer questions that way. Or you can— now there's non-invasive technology to track visual attention. So for example, you could present various scenes to a captive primate via video or something else and actually track how intently they're focusing on something. And we are able to measure how novel something is by how long animals look at it, for example.
John Markoff: I noticed that you've studied more than one community of primates. In the world, is there seen as a hierarchy of intelligence and who's closest to us?
Elizabeth Lonsdorf: In general, the great apes, the, um, the chimpanzees, bonobos, gorillas, orangutans. Those are the animals most closely related to us and therefore assumed to have the most kind of overlap in cognitive and psychological underpinnings, so to speak. Of those four great apes, the animals that we are the most closest to are chimpanzees and bonobos equally. So people are very interested in specifically chimpanzees and bonobos in terms of comparative psychology, comparative kind of evolutionary biological basis of behavior in those two species, because they're, they are the taxon present on this planet right now that is the most closely related to us. And indeed, they show some of the most complex cognition that we've seen. They see some of the more complex behavioral responses to situations that seem to have the most kind of overlap with human capabilities. What's interesting about bonobos and chimpanzees is that they're actually extraordinarily different in their social behavior with each other. So chimpanzee society is, is based in large part on dominance and aggression and kind of the alpha male keeping a very strict, firm hand on his community, and all males being dominant to all females in chimpanzees. and in bonobos, females and males have equal dominance, and disputes are settled with sex and copulatory behavior in bonobos rather than aggression. So people are kind of fascinated, like, these are the two animals most like us, but they're very different, so which one? You know, which one is kind of the proto-human? And so that's a large area of study right now.
John Markoff: And within the chimpanzee world, are there more Draconian and less Draconian communities? Do you see variation in structure?
Elizabeth Lonsdorf: There's not as much as you see variation with individual alpha males. And people think that that's based on kind of their generalized personality. You've got alpha males that are, that are really despotic and alpha males that are more chill and egalitarian. You know, and there has been some work to actually rigorously quantify that in terms of aggressive rates. And things like that. But alpha males seem to have different dominance styles. Yeah. Yeah.
John Markoff: And on this spectrum that you—
Elizabeth Lonsdorf: much like human alpha males, I should say.
John Markoff: And the whole point of the Center for Advanced Study in Behavioral Sciences is to get this interaction. So your particular problem seems like it would be very interesting. And what was it like in interacting with this group for you? From your primatologist community in dealing with a social science community that— and I just wondered.
Elizabeth Lonsdorf: Right, so what was interesting is that the range of responses I got from my colleagues here at CASBS ranged all the way from, "Of course they grieve and understand death. Why are you even asking this question?" to, "I don't think you've convinced me of anything. I think that this thing just stops moving and they walk away." So, and that was to be— expected, I think. And I had a lot of conversations afterwards of like, you know, why is this such an interesting question in primatology right now? Why are people so unwilling to think about animal grief and animal mourning and things like that? And I had to kind of go back and explain to them that those underlying kind of history of primatology is to attempt to be very rigorous in terms of testing hypotheses about, you know, the adaptive function of behaviors, and being careful not to imbue animals with human-like cognition, emotions, and feelings unless you can essentially prove it. It's interesting because in primatology, kind of right from the get-go, the field was very apprehensive about ascribing human-like emotions, capabilities, personalities to non-human primates for fear of being regarded as too anthropomorphic or being regarded as kind of some fluffy weirdo that, you know, some bunny hugger scientist. It was considered not appropriate and proper science, and in fact Jane Goodall herself was chastised by the academic establishment for naming the chimpanzees that she studied rather than giving them, you know, numbers. Which was seen as much more rigorous and removing kind of the individualization of the chimps. And Jane, you know, as she has done many things, blew that off and said, "Well, of course they're individuals with individual personalities and emotions and feelings." And she was really chastised for that back in the 1960s when she started talking about that. So as primatologists, we are kind of trained and admonished not to anthropomorphize.
John Markoff: Has it been useful, or has it changed your paradigm in any way to be here?
Elizabeth Lonsdorf: Well, it's been really useful in the sense of, like I said, those— that diversity of responses I got from like, "Yeah, of course," to, "Yeah, no, I don't believe it at all." I mean, that really helped me think about how I can talk more broadly to the public about these issues of animal emotions, what we know about them, what can we know about them. And that's been, you know, quite interesting and quite fun for me. And also it's been interesting and fun for me to see the diversity of questions that my fellow fellows are working on, that they come to me and say, "Hey, what do we know about this in non-human primates?" And it usually something. I mean, usually there's an evolutionarily interesting set of data that I can bring to bear on the question that they're working on. And I've had a lot of those conversations.
John Markoff: I've noticed there's not only a scientific literature, but there's a big popular literature that seemed to report recently on a bunch of stuff. I felt like it was very anthropocentric. There was a desire in the popular press to interpret the scientific literature as suggesting that chimps grieve or maybe know about death. Have you looked at the popular literature and do you think it tends to read into the scientific research?
Elizabeth Lonsdorf: Well, yes and no, because, you know, when you talk about making sure you're scientifically rigorous and not anthropomorphizing, and that's kind of what's driving our careful analyses and careful, you know, interpretation of these cases, that's the rigor of the scientists addressing it. But then you actually talk to people who are like, "Oh my God, my dog was super sad for like 2 months after our older dog died." You know, you talk to people that live with animals and they say, "Of course they have emotions. Of course they feel sadness. Of course they recognize that an individual that's important to them is gone." You know, and they're talking about something, you know, so to speak, lower down on the evolutionary scale, like a dog or a cat. So in some ways, the responses I got from my fellow fellows of, "Of course," and, "Yeah, I don't believe you at all," that gives you kind of an idea of the responses you can expect to see in the popular literature of people just on the one hand saying, "Of course animals do this. I see it in my dog every day. Why wouldn't a chimpanzee, the animal most like us, have these complexities of emotions and cognition?" And then you've got others that are just like, "Yeah, animals are animals.
John Markoff: They're nothing like us." So in the spectrum you described in the social science community, this wide range about conception of death, where do you put yourself?
Elizabeth Lonsdorf: Well, that's what I'm working on figuring out. I mean, my feedback from my colleagues was really useful in terms of I got feedback that specifically one of my questions I was posing to the group is, if you're not convinced, what would convince you? What kind of evidence? And I got some helpful leads from my colleagues here on like, this is the data that you could show me that would be more convincing to me. This would convince me of XYZ. So since my talk, which was just, what, a couple weeks ago, I've been working on seeing whether we have the data to to address some of those particular questions. For the people that are like, "Yeah, of course," you know, I just kind of check that box. But it has been really helpful in terms of thinking about how to address such a kind of tricky question in a nonverbal animal and other proxies that would be more convincing.
John Markoff: Given that, let's make this a last question. Let's say you convince yourself and the scientific community that there is an abstract concept of death within the chimpanzee species? How significant would that be in the field?
Elizabeth Lonsdorf: Well, you'd have to ask reviewer 2, as always. They have the say. I mean, I think that, you know, recently in kind of behavioral and non-human primate science in particular, people have been very interested in this and trying to pull together quantitative support for not only if, but how. Like, if we think they understand what death is, how is it similar or different to a human conceptualization of death? I think it'd be really interesting either way. Like, either saying, "Yes, we have convincing evidence that, for example, they understand that death means non-functionality." It means this this individual has ceased to be an agent and is now something more like an object. But for example, we're not going to have evidence that they know that death is universal and will happen to all things, including oneself. That's a really hard thing to figure out with using nonverbal methodologies. So I mean, I think it'll be a large contribution in the sense that there hasn't been enough cases in chimpanzees kind of analyzed quantitatively in the same way to start to address some of those proposed hypotheses for what they do and don't understand.
John Markoff: Yeah, that's great. Thanks so much for this. Thank you. Elizabeth, thanks for spending time with us today. As always, for our listeners who want to know more about this topic, take a look at our show notes for links to interesting resources.