Primate Politics: Intergenerational and experimental evidence with Dr. Jenny Tung

each other sequentially. And so we can do this little manipulation, which we think of as in some ways equivalent to, you know, if we were able to take a community of humans and sort of randomize how much money they made or how much educational experience they'd had and watch what happened next, right? We can't do that in humans, but we can do that in these captive primates.

recognized stress experts from UCSF, UCLA and Yale. I'm so happy to share our second episode focusing on social status and health with you. Last month, we heard from Dr. Michael Marmot on human hierarchies and health, and today you'll hear from Dr. Jenny Tung. She's an evolutionary anthropologist and geneticist, who discusses her intergenerational and experimental research showing how the social environment

affects health and lifespan in non human primates. I especially loved hearing about her creative methods to experiment with social hierarchies in her lab, and the very special experience of collaborating with other women who have previously led the Amboseli Baboon Research Project in Kenya. I hope you enjoy the episode. So, I'm so excited to welcome Dr. Jenny Tung to the podcast

today. Dr Jenny Tung is the Director of the Department of Primate Behavior and Evolution at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a professor of evolutionary anthropology and biology at Duke University. She co directs the Amboseli Baboon Research Project, which started in 1971 and is one of the longest running primate field sites in the world and located in Kenya.

Dr. Tung investigates the genetic and genomic consequences of the social environment among baboons, rhesus macaques and other social mammals. She's advanced the science on social determinants of health by adding DNA analyzes to decades of behavioral observations in baboons to advance our lifespan

understanding of social influences on health. And as we'll talk about today, she's really combined these lifespan studies with creative experimental methods that actually allow us to zoom in on causality between the social environment and health. And it's fitting that she was named a MacArthur Fellow in 2019 for the depth and translational importance of her research. Welcome, Dr .Tung, we're so excited you could join us all the way from Germany for this episode of the stress puzzle.

That is, these are animals that may be living cheek by jowl for years or even decades, who have their favorites and who have their frenemies and who have other individuals with whom they pretty routinely compete for the things that are good in life for a baboon. These types of social interactions are really obvious to any observer, I think even a casual observer, if they spent some time watching the species that I study, baboons in Kenya.

I also study rhesus macaques in captivity, so two monkey species that are pretty closely related to humans, they would they would easily see, you know how a lot of what makes a difference to an animal's day to day experience is social, and in fact, it's those social interactions that we often find, I think many people, even people who go see animals at the zoo, find most

compelling. They're compelling to us because they remind us of the things that make a difference in our own lives, what we've been able to do now because we can watch them, not only just for, you know, a few minutes or a few hours, but for days and days on end, from birth till death, is to try and understand how those interactions compound to

influence like big outcomes, like how long animals live. I mentioned that these are animals that are good models for humans, because they live a long time and they're socially complex. But for example, the baboons that we study in Kenya live about, you know, twenty, twenty-five years at the

longest. And so that's a long time, but it means that in the course of the field studies that we've been doing, which started in 1971, we've been able to watch, actually, many generations of the animals, so we can ask about what happens in early life and whether that has echoes years or decades later, or even in what happens to their offspring. As you alluded to, what we found are some pretty striking parallels to humans.

For instance, we now know that the biggest predictor of lifespan, at least, that we've identified so far is the quality of baby baboons' early life, and basically infancy and the first few years before they reach sort of reproductive maturation, before they reach full independence as an adult. So, in ways that are very similar to humans, what we see are that things like social isolation, low social status, certainly loss of the mother. Don't necessarily, you know, kill

those animals immediately, right? They aren't lightning bolts from the sky, but rather, seem to have these sort of latent effects that can shorten their lifespans by as much of a decade, which is a huge, huge effect size, even in humans, and even more so in a species like the baboons.

many different disease outcomes. It would be wonderful if you could sort of point us to where you're really able to zoom in in your experiments and work.

differences in social status. We've done that work, both in the baboons that I talked about, which is a field population, a natural population of wild animals, but for causality, where we've gotten sort of the most bang for our buck, I think, is in our studies in captive socially housed macaques. So, another social primate, there, we've been able to manipulate long term social status for months or years at a time.

Simply by manipulating how these animals are housed together, we decide who gets to go in to a new housing unit in what order. And it turns out that in this particular species, in females, at least the individuals who get there first tend to be the ones who reach the top of the social ladder, and they sort of insert

below each other sequentially. And so we can do this little manipulation, which we think of as in some ways, equivalent to, you know, if we were able to take a community of humans and sort of randomize how much money they made or how much educational experience they'd had, and then said, and watch what happened next, right? We can't do that in humans, but we

can do that in these captive primates. So when we do that, what we see are pretty extensive, pretty profound differences in the degree and the places in which genes are activated or sort of suppressed in the immune system. And perhaps most interestingly, we see differences in how those

genes respond to signals of pathogen threat. So basically, we can take cells from our animals and we can expose them in a dish or in a tube to something that looks like a bacterial invasion or a viral invasion, and we see systematically that the cells from individuals that we have manipulated into being low ranking are different than the cells that we obtain from individuals that we have

manipulated into being high status. And then what we can do is actually manipulate those status hierarchies again, so we can make individuals who are low status high status, and individuals high status, low status, or keep them, you know sort of the same across successive years of our experiments. And in general, what we see is that animals body's, their cell's, their immune system, tends to reflect their social environment at the time we're actually sampling

them. So, this is both a pervasive effect and also, perhaps in a positive light, pretty plastic too if the social environment can improve.

conditions of income or other measures of SES. So, to be able to get at that through non human primate models, I can't underscore how important that is for our field. So, just thinking about that creativity and and sort of methodological development. Where do you think that there is the most potential now regarding methods, whether that's in non human primates, humans, any any population that you might be studying, what do you think we're sort of missing? If you could capture something?

circulating immune cells, right? These, these are white blood cells that are going around your body, and I'm telling you that they behave differently depending on the social environment of the animals that they're in. Other people study heart tissue, for example, or other part organs that are not the central nervous system. So, that raises this natural question of how those cells or those tissues even know that they're in you know an advantaged or disadvantaged

person? In other fields, particularly social neuroscience, there's a great deal of effort going in now into understanding the regions of the brain and the particular neurons that sense social experience, whether that is social relationships or the absence of them, loneliness or social hierarchy. And I think that work is really fascinating, but it often stops once those neurons are identified, which is hard

enough as it is. And the question of how that that sort of sensing and engaging experience in the central nervous system then connects to the periphery, I think, is one

of the biggest questions for for the field, right? We really want to be able to go soup to nuts from, you know, individuals are in this sort of complex social stew, and they're figuring out where they fall in that in that social milieu, and then somehow that is being translated to the rest of the body in a way that can either confer good health or that can confer poor health, and can making that entire connection from top to bottom is a place that that I think would really be beautiful to see in

upcoming years.

out. You know, in the baboons, for example, when we're talking about early life, we tend to be thinking about sources of adversity or advantage that are relatively uncorrelated with each other, so that, in principle, would allow you to identify that one big thing, if it exists, and so far, we haven't found it. It's multiple ways adversity and advantage can happen in multiple ways through which it can emerge. I think it's, it's quite important. You asked about going into the

future. What do we do about that? I mean, one sort of boring answer, but I think a valuable one is, well, we keep on figuring out what those are, right, and we keep on seeing how they add together to either compound one another or mitigate one another. I mean, then that feels very important work to do, even though it doesn't have the sort of sexiness of a single smoking gun. You know, I think about research is our job is to explain what is actually happening in the real world,

even if it's not what would be convenient for us. So, I think that's part of the question. I think there are more targeted subsets of that question, which you'll be very familiar with already, right? These are the same questions that people are asking in human research. How do the experiences in early life potentially interact with experiences that happen in adulthood? Right? That's really important for thinking about the possibility for resilience. The message we don't want to send,

we hope, right? Is that what happens in early life, is it? And then, then, you know, the life, life course is written. And so that's something we're very interested in. Now. We're also quite interested in how one dimension of the social environment, social status, which we've talked about already might interact with other dimensions of the social

environment, like positive social relationships. Both are major predictors of of lifespan outcomes in humans and in non human primates, but they actually aren't studied as often in conjunction as as I hope they will be in the future.

access to healthcare, or even land on individual blame in terms of health behaviors and things like that. And so to really be able to get away from that and focus in on the social environment in this way, and again, in those like tight experimental designs, I wonder what sort of given the complications in human research, if you have any thoughts on what stronger inference and better data would look like for us?

your poison, right? So, a couple of things that I think would be useful would be if there was more bridging between people who are interested in these questions, in working in human populations, with all the advantages and limitations of working with humans, and people working in animal models, because that could lead to the generation of methodological tool kits that, perhaps, in the best case scenario, can be deployed very much in parallel, across across humans and other

animals, right? It'd be great if, when we're, you know, out there, for example, measuring stress hormones, that we're doing it in sort of a comparable way with sort of comparable samples where possible, and that would really facilitate comparative studies. Sometimes that won't be possible, but then

at least we should be talking about interpretation. There are ways in which, for example, social hierarchies in the animals I study, I think, are really good models for some of the things we see in humans, and there are other ways in which social hierarchies in animals are nothing like what we generally observe in humans. And those conversations would, I think, help even the in the absence of directly analogous

methods. And then, the other thing I would say about what kind of data would be useful, I'm going to leave it to you and

your colleagues to figure out how to do this. But there are certain types of measures that we've invested in pretty heavily in the systems I study and others have invested in in other animal systems, like, for example, stress hormone measurements, glucocorticoid measurements, and everything our data tells us is that all of those data are extremely noisy and they are informative, but we need tons of repeated

measurements in order to pull those out. And so, for example, in the baboons, because we use non invasive sampling techniques that we can repeatedly sample these same animals across their lives, we often have hundreds or thousands of measures from the same individual, and that allows us to sort of help see a signal

through the noise. And again, I see you shaking your head. I know that would be really difficult to do, but I think some of the biomarkers that folks are really going after, or the systems that those biomarkers tend to represent, simply are just going to take lots of repeated longitudinal measures to get. I hear exciting things coming out of the human literature about wearables and non invasive measures for regular assessment, and hopefully those will help get over that major challenge?

in this way. And, so going back to what you might be able to tell us about the intergenerational effects that lot of care and have to do a lot of learning from adults and you've been seeing in these baboons related to the social their peers in order to be successful. And so that made it environment, as we start wrapping up focus a little bit on the intergenerational side. very likely to us that things that happen in one generation might sort of percolate to influence what happens

of their own. But what we find is that their kids are less likely to make it through the juvenile stage, so they experience higher rates of offspring mortality than in their peers who didn't lose their mothers early in life, and that's observable, even if we take into account everything

that happened to those potential offspring as well. So here, we're seeing intergenerational effects that are separated by again years or even decades, where whatever killed that that question, I would love to know if there is a particular finding potential grandmother is not affecting that grand offspring, but it seems to be sort of connected through the experience from your career that feels the most meaningful to you, either

of that grand offspring's mother. We think that this is probably related to sort of very granular processes of care or responsiveness or maternal condition, and that's something we're quite interested in getting a handle on in future research. because of the importance of the results or something about the process itself?

process perspective and a result perspective. One, the effect we found was huge and perhaps totally unsurprising to researchers who've been doing similar sorts of work in humans, but the way we did it was directly inspired by sort of these adverse childhood experiences, frameworks that were developed in humans, and really not by the type of biologists that I interact with and that I was trained by at

all. So, we kind of said, well, let's just sort of take this thing that these human people do that feel totally abiological and see if it works. And it worked remarkably well. It's probably the biggest effect size I'll ever find in my career. It's already happened. I'm done, and it sort of helped catalyze a huge amount of work for us subsequently going where is this

coming from? I also had the chance to do that in really close collaboration with the other women who have led in both the past and the present, this long term field study, the Amboseli Baboon Research Project that we've been talking periodically about, Beth Archie at the University of Notre Dame, who is the other co first author of that paper, and Susan Alberts, who's been working with the baboons, really, since the 80s, and Jeanne Altmann, who founded the project in 1971, and

sort of scouted out that landscape in the early 60s. I think that may be the only paper where the four of us are the authors. And so it was really special, both in the sense of thinking about generational life course processes in the baboons, and being this kind of representation of this long term collaboration, this long term matrilineal collaboration, that has meant a lot to me personally, too. So yeah, that was a big one for me. Thank you for asking.

totally agree with you. I, we need more of it, and those are the kind of dream studies to be able to connect and look in parallel at different in different populations. So, I hope we encourage anyone listening to go towards that and thank you again. Dr Tung, for joining today.