Ep 107: Cooperation versus conflict and the path to multicellularity (with Joan Strassmann and David Queller)
Joan Strassmann
David Queller
How can we reconcile the evolutionary problem of cooperation? What can social amoebae tell us about the origins of multicellularity?
In this episode, we talk to Joan Strassmann and David Queller, professors at Washington University in St. Louis, about the evolution of cooperation and conflict. From social insects to humans, we can find instances of individuals seemingly sacrificing fitness for the good of the group. But, truly altruistic behavior poses a problem for evolutionary biologists because it challenges the assumption that natural selection favors individuals over groups. We talk with Joan and David about their work with the social amoeba, Dictyostelium discoideum. This species is known for its remarkable developmental cycle: when there is no more to eat, the starving amoebae aggregate into a slug-like organism, which then forms a fruiting body that releases spores in hopes of dispersing to a better place. The problem, evolutionarily, is that only a fraction of the cells in the fruiting body get to live on through offspring. This facultative lifestyle and the ability to combine genetically different cells makes D. discoideum a prime study species for understanding how relatedness impacts cooperation and conflict and the possible origins of multicellular organisms.
Towards the end of the episode, we also talk about Joan’s new book Slow Birding: The Art and Science of Enjoying the Birds in Your Own Backyard.
Cover photo: Keating Shahmehri
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Cameron Ghalambor 0:07
Marty, do you ever read The Far Side cartoons by Gary Larson?
Marty Martin 0:10
Of course, I love The Far Side, Larson was a master at capturing interesting biological insights in a single visual.
Cameron Ghalambor 0:17
My favorite Larson cartoons, is this image of Lemmings, with glazed over eyes running down the hill and jumping in the water. The cartoon says take on the now disproven idea that lemmings altruistically commit mass suicide to help regulate their populations.
Marty Martin 0:31
Yep, I know that cartoon and there's one lemming with a life preserver around his waist and a sly look on his face. I love how Larson captures a really complex idea with a cartoon, it's that any individual in that population chooses to act selfishly and not sacrifice itself. That little living should have a huge advantage.
Cameron Ghalambor 0:48
The tension between whether individuals should act selfishly or altruistically within social groups has fascinated and challenged evolutionary biologists since Darwin wrote On the Origin of Species. In fact, Darwin recognized that individual worker bees were sterile, so their mothers have all the fitness benefits associated with reproducing.
Marty Martin 1:06
He suspected that this apparently altruistic behavior had something to do with the close relatedness of bees in the colony. But it wasn't until the 1960s When Bill Hamilton showed mathematically how altruistic behavior could increase within a population, even if it was costly. By helping the relatives, altruistic individuals still pass on their genes to the next generation.
Cameron Ghalambor 1:25
We refer to this process as kin selection because it's selection for the evolution of traits that benefit relatives. The idea is closely linked to the concept of inclusive fitness, where fitness is not how many offspring you produce, but how many offspring equivalents you produce.
Marty Martin 1:41
Remember, parents and sexual species only pass on half of their genes to their offspring, but they also pass on one quarter of their genes to their grandchildren. So two grandchildren are the offspring equivalent of one child, which is why JBS Haldane famously joked that he would willingly die for two brothers or eight cousins,
Cameron Ghalambor 1:58
Hamilton's ideas were extremely influential, not only for explaining cooperative behavior, but also how social groups as a whole evolve. And while we might think of social groups as being a colony of bees, a troop of monkeys or even a human society, a social group can really be thought of as any group where individuals with varying degrees of relatedness interact with each other.
Marty Martin 2:20
For example, we can think about the cells that make up a whole organism as a social group. Individual cells form tissues and organs, which all interact with each other and highly cooperative ways.
Cameron Ghalambor 2:29
But it's not always cooperative. Think of a mutant cancer cell that acts selfishly and evades the body's mechanisms to suppress uncontrolled cell division. On the individual cell level, cancer cells benefit by making more copies of themselves. But on the organismal or group level, this ultimately has a really negative effect.
Marty Martin 2:48
So understanding how individual cells in a body lemmings on the tundra or even humans and complex societies become cooperative and resolve conflict are very fundamental problems in biology.
Cameron Ghalambor 2:58
Our guest today, Joan Strassman, and David Queller from Washington University in St. Louis, have been at the forefront in shaping our thinking about cooperation and conflict and social groups. We talk with John and David about the history of kin selection and inclusive fitness, and how they relate to the strength of selection acting on individuals and groups.
Marty Martin 3:17
For the past several decades, Joan and David have used the social amoeba dictyostelium discoideum, as a way to understand the dynamics of what happens when cells with different degrees of relatedness come together and form a multicellular slug.
Cameron Ghalambor 3:29
As single cells. These amoeba are solitary foragers on soil bacteria. But when the food runs out, thousands of cells gathered together and cooperate to form a multicellular slug. The slug then moves toward the light and produces a fruiting body made up of a long rigid stock that supports other cells, which differentiate as spores. And those spores disperse for greener pastures,
Marty Martin 3:51
About 25% of the cells that form the stock die and the sacrifice themselves for the group. So given a preference, no cell wants to end up in that stock. If there was a way to cheat the other cells and instead end up producing spores just don't become a stock.
Cameron Ghalambor 4:06
In nature, these multicellular slugs are often made up of a single genetic clone. And as predicted by kin selection, cheating is rare because all cells are clones.
Marty Martin 4:15
In the lab, Joan and David had been able to manipulate the number of clones within a slug. To test experimentally how changing genetic relatedness alters the balance of cooperation and conflict. They've shown directly, that they can increase the frequency of cheating and even break down cooperation altogether, by reducing the genetic relatedness within that group.
Cameron Ghalambor 4:34
We talk with Joan and David about some of the fascinating things they've discovered and how they transition to working with dictyostelium as a model system,
Marty Martin 4:41
Their studies have not only been valuable for testing major aspects of evolutionary theory, their work also has potentially important implications for the very origins of multicellularity.
Cameron Ghalambor 4:51
In addition to social amoebae, we also talk with Joan about the inspiration for her new book called Slow Birding and the importance of appreciating bird behavior.
Marty Martin 4:59
Wow- from kin selection to slime molds to watching bird behavior. We covered a lot of ground in this episode. So let's jump in.
Cameron Ghalambor 5:06
I'm Cameron Ghalambor
Marty Martin 5:08
And I'm Marty Martin
Cameron Ghalambor 5:10
And you're listening to big biology.
Cameron Ghalambor 5:21
John Strassman and David Queller. Thanks so much for joining us today on big biology. We're really looking forward to talking to you about your research and your perspectives on the evolution of cooperation, the levels of selection and the implications for the evolution of organisms and social groups. But we also want to talk a little bit about a new book that Jones published with a funny title Slow Birding. So looking forward to talking with that to you about that as well. So to begin, let's orient around the evolutionary problem of cooperation. We see striking examples of cooperative behavior within us social insects cooperatively breeding birds, and of course, within human societies. Can you tell us a little bit about why cooperation and things like altruistic behaviors, really challenge evolutionary biology and the kinds of theory that this type of cooperation has inspired?
Joan Strassman 6:21
Darwin was really one of the first to notice that his theory of natural selection depended on traits being passed down that were advantageous to the bearer. So the problem is, if you help someone else at a cost to yourself, if there's no cost to yourself, there's no problem. But if there's a cost to yourself, why should you help someone else? Won't that mean, your genes will have Darwin didn't know about genes, but that you'll have fewer progeny> So it's really a cost of altruism, it's a cost of helping others at an expense to yourself. And this was thought to be a big problem for a long time. The simple answer, there's two simple answers. One simple answer is if you help relatives, you are passing on copies of your genes, by helping individuals that are not exactly your own progeny, your own children. So that's, that's kind of an easy answer.
But it has lots of really fascinating ramifications. In terms of what kind of help that is. So it's true for social insects, it's true for a lot of cooperative breeding birds, certainly true for humans. So it's almost easy to talk about helping relatives. Helping non-relatives means you have to get something out of it. So then that caused a big increase in understanding exactly what the benefits of mutualisms are. And then another big interesting side is, if you're past helping pass on genes, there can be conflicts within families, closer versus more distant relatives. Then another big area that came along just from these ideas is interest in how do you even figure out who you're related to? And you know, if you think about it, how do we figure it out? It's kind of like if mom's giving him food, he's probably a relative. So yeah, so that's, that's the broad picture.
Marty Martin 8:45
So I guess you didn't say his name. But one of the people that really helped us mathematize at least these ideas was William Hamilton, Bill Hamilton. Can you tell us something about the concept of inclusive fitness and how that resolved the evolutionary problem of altruism.
David Queller 9:05
Inclusive fitness, the idea of inclusive fitness goes along with the idea of kin selection, and he's the person who came up with both, although we didn't coined the term kin selection, and actually didn't like it at the beginning. But Bill Hamilton, let me mention first that Darwin, amazingly, kind of foreshadowed the solution, even though he didn't know about genes. He didn't know that much about heredity, but he did realize that family members were similar and thought that, for example, the evolution of sterile workers in the social insects had to do with helping family members.
So fast forward to the early 1960s. Many people were not thinking about the problem of altruism, in those days. So one of Bill Hamilton's contributions was to bring it to the fore, but also to provide the solution of kin selection and inclusive fitness. So as Joan said, the idea of kin selection, is that you by helping your relatives, you are transmitting copies of your own genes. So if there's a gene for altruism in you that would be lost if you suffered a cost to your fitness, that can be restored, indeed, over compensated if you help enough relatives to pass on the gene.
Marty Martin 10:15
Right. Okay. So I didn't what you just said there, David, I didn't know that Hamilton sort of revived this idea. I mean, it wasn't something that was all that exciting at the time, or all that popular? What was his inspiration to put all the effort into it?
David Queller 10:31
That I don't know if I can mention that, a year or two before Hamilton published biologist named Wynne Edwards published a group having to do with what we now call group selection. And so he was considering the problem of altruism as well and trying to solve in a different way that at least initially wasn't very productive. And I don't know if that's what set Hamilton off. I've never, I've never heard him say that. As far as I know, he kind of got interested in it through his own readings of, for example, Ronald Fisher, one of the great population geneticists.
Marty Martin 11:07
Okay. So since we brought up Wynne Edwards in and the group selection that the moniker group selection, what is that I mean, it has something to do with cooperation among non relatives, presumably.
David Queller 11:19
Presumably, but that's, that's an interesting slant on it. Some people view it that way. But in fact, so when it went, when Edwards proposed the idea, he was thinking about things like animals regulating their population sizes. So we envision flocks of starlings coming together and flying around in big flocks, and giving vocalizations so that each of them could assess the population size, and then decide if the population size is too big, I'm going to hold off on reproducing so we don't extinct ourselves. And that was kind of a novel argument. And he realized that if it was going to work, there had to be selection above the level of the individual, because individuals back off on their own reproduction would do worse.
Now, that actually doesn't work well, if it's with non-relatives, because non-relatives are a random selection of the population. And genetically, if you back off on your reproduction, costing your altruism gene, and only help a random segment of the population, they have the altruism gene at random. That doesn't change the frequency of the gene. So the problem, he raised the problem of altruism, he had a possible solution. But he didn't think much about the relatedness side, the fact that that groups would have to have heritability, in fact that the group advantages would have to be heritable. And that's what comes when you have groups of relatives.
To answer your question about group selection, when Edwards published his book, on group selection back in the 1960s, it was very incomplete. It didn't consider the heritability that comes with groups of relatives, and so forth. Over the years, a theory of group selection has developed kind of in parallel with kin selection. People viewed them as competitors, but they aren't really. They're kind of different ways of slicing the way selection works. And as long as group selection considers the heritability of group effects, which usually comes from relatedness within groups, it can work. And it is explanations, which are, I think, essentially identical to kin selection explanations, but they're framed in different terminology. And it's caused a huge amount of confusion.
Marty Martin 13:31
I've tried to get my head around what you're saying. So group selection, historical group selection arguments, I guess, after when Edwards, when they're framed in a particular way, sort of having a version of kin selection at bottom, they end up being the same kind of thing. So there's some other group selection theory, that is its own thing. But a lot of it is resonant with traditional kin selection thinking.
David Queller 13:54
I think the two theories are, if you frame them properly, are essentially identical. There's no other group selection. I mean, there are other things they call group selection, which are effectively individual selection, which we knew about all all the time, you do something which happens to be good for the group, but it's good for you too. And that's why it evolves.
Marty Martin 14:14
And this comes down to the heritability issue. I mean, that's that's what's core because groups don't have something inheritable, generally
David Queller 14:21
Right if the groups are randomly formed, then traits are not going to be heritable, except to the extent to which you express it yourself. And then then it's individual selection. But I've come to believe that, that sometimes, thinking about the world in a group selection way can be useful way to think of things. And that's, that's a change in my thinking over the years.
Cameron Ghalambor 14:42
So I've recently started reading, Samir Okasha’s book on multi level selection. And I don't know if this touches on what you were saying, but he sort of seems to be presenting the case that the sort of dichotomy between group selection and kin selection that really, they are two sides of the same coin and, very compatible with one another. And a lot of the previous debate seemed to go away. I'm assuming you're familiar with some of his work.
David Queller 15:15
Yeah. Yeah, that's that's pretty consonant with my own views, but not necessarily with other people. There are people on both the kin selection side and the group selection side who would not agree with that.
Cameron Ghalambor 15:24
Yeah, so Samir is going to join us in a few weeks as as a guest as well. So we're, this is a good segue into.
David Queller 15:29
Yeah, that should be interesting.
Marty Martin 15:31
Yeah my head starts spinning to think about any of this. And I haven't started in on some Samir’s book yet. But I think the concept of multi level selection to the extent I'm familiar with it is, is really trying to draw explicit attention to where selection is acting. I mean, we've invoked individual, we've invoked group, what's your feeling about the sort of relative effects of selection? At what level is it the strongest? Or is it the most consequential? Or is that just a silly question? Because multi level selection is really the way to think about things?
David Queller 16:09
My take on it's almost a definitional one, the thing that we regard as an individual is the level at which selection is most potent. So we're multicellular individuals, we call ourselves individuals. But we're groups of cells we originated from, from single cells, dividing and producing groups of cells. We don't think of ourselves as groups, however, we think of ourselves as individuals, because that's what selection has molded.
It's a little bit less clear within the social insects, for example, but there's been a long tradition of thinking of social insect colonies as essentially individuals, because they have been subjected to such a long history of I would say kin selection, but you could say group selection, that colonies are adapted in complex ways
Marty Martin 16:56
Right I'm gonna use to get you to explain that were potent that you use just a minute ago, what? What do you mean by potent?
David Queller 17:04
Well, for selection to be potent, selection should be strong, there should be big advantages or disadvantages, and it should be heritable. It's sort of got those two components. And if either of those components is not there, then selection is going to be impotent. If you don't have heritability, or if you don't have selection on the trait.
Marty Martin 17:23
Right. And I think that to just to circle back to Wynne Edwards, that was one of the arguments that I remember when Jesse Williams was first introduced to me that, you know, it's the rate of evolution, sort of the potency of selection on individuals, when the generation time is that much shorter than the age of a group. It's not just the heritability, but you have another issue that comes up there. So Joan, you just said nah, a minute ago with the multi level question, what's your, what's your perspective on?
Joan Strassman 17:49
You know, I just feel like there's two kinds of people in the world, there's people that like to have everything be more complicated. There's speakers that likes to give talks that nobody can understand. And then they feel like that makes them more powerful. And there's people that like to be as simple as possible and give the kind of talk that almost makes the listener feel like they've either discovered the same thing, or already knew it, and real clarity. And I think that the mult-level selection, people are the obfuscators and that kin selection is easier to understand, it's clearer, you know, I just feel like multi-level selection is is the embarrassed, counter to the fact of to the failure of, of what I call old-style group selection, then they say, multi level selection, and it's so complicated. You don't really understand it, and that's their salvation.
Cameron Ghalambor 18:55
But, Joan, I guess I would, I'm curious, though, I mean, there are, aren't there? I mean, there are limits, it seems like to kin selection. So just as you were talking about earlier there, you can have like groups of unrelated individuals that seemingly cooperate with one another. So in those cases, is it simply just mutualisms that lead to cooperation leading to higher fitness, and you leave out the relatedness component to it?
David Queller 19:27
That actually kind of goes back to the question we had earlier that I think I didn't answer completely about kin selection and inclusive fitness. So they're things that don't involve kin selection, because you're not affecting relatives, many things. But the concept of inclusive fitness was taking the initial concept of individual fitness and adding in the kin selection component. So inclusive fitness would cover those kinds of cases that you're talking about, both individual selection and possibly the added component of kin selection. So
Cameron Ghalambor 19:58
Ok so that keeps it simple. without having to complicate it.
David Queller 20:01
Yes, yeah.
Joan Strassman 20:02
But the but the other thing is to understand mutualism is, you know, if they're not related, if there are different species, things like that, you have to understand the benefits to the individuals. And yeah, I don't know about if that's really a particular focus of multi level selection, but I mean, I'm working for my new book, I'm working on a chapter on mixed species flocks. And, you know, they're fascinating in the tropics, they're really stable. And it'll be, you know, a pair of this species, a pair of that species. And as a group, they'll defend a territory. It's all individual selection. So in you know, some multi species flocks, you have a bird say, like an ant shrike, who gives alarm calls, and it's clear that they only give alarm calls if they have relatives in the group. But then there's all these other birds that forage near them, and take advantage of the of the alarm calls. So the ant shrikes don't have to have a benefit from the other birds, just because you're together doesn't mean that the natural selection is going on.
Marty Martin 21:29
One thing that seems to be coming back, the selection is strongest at the level of the individual, maybe it has its most potency there to use David's- why? Why is it the level of the individual, that it's the strongest? And I asked that because cam and I and our other co host Art Woods had been enamored for the longest time that organisms are special kinds of things. And we have a different version of “special” maybe then you guys do, but you've been thinking about that a long time. Why is individual the locus of selection?
David Queller 21:57
Well, again, I think it's I think it's because we define individuals as those things which are agents in the world that are highly adapted. They are the level where selection is potent. And if it's if it's a bacterium doing that we define the bacterium as the unit of selection, if it's a multicellular organism that's doing that we define that as an individual, and some of us even define social insect colonies, as individuals. What we view as an individual is a result of what has been crafted by natural selection over the years.
Joan Strassman 22:31
I mean, I think “what is an organism?” is a super important question. And it's one Dave and I have written on Dave's had some brilliant ideas on this topic. And yet you know, it's almost not a field of study. And there's all these people just, you know, losing sleep over what is the species and all this stuff on speciation. And they're, you know, they're pushing the envelope by millimeters. But that's what people study whereas organismality is, is wide open, and that, you know, that's the target of natural selection. There's, there's lots of really interesting cases of, you know, obligate mutualisms, lots of marine things, the dictyostelium, we work on things, at the borders of what is an organism? I mean, that's how science work, doesn't it? Everybody works on the same thing. And then there's these huge gaping holes that people don't go after.
David Queller 23:34
It is catching on.
Marty Martin 23:35
Yeah it mean, it does feel like the tide is kind of turning. But do you have a feeling for why I mean, it's so incredibly prominent it is it seems to be the defining thing, at least in terms of how a lot of us started this field. We get excited by chimps on TV, or, you know, sequoia trees or something like that. We get excited about organisms, and then we move off into other places. But what's been the reason for this sort of slow pursuit of a definition or some sort of consensus on what organisms are?
David Queller 24:02
Yeah, I'm not sure maybe because it's largely self evident? Or maybe because people didn't have the theoretical framework for it? I mean, for us that the theoretical framework involves this social selection and conflict and cooperation among units. Yeah, it's puzzling. I mean, people have talked about what makes an organism, more so what makes a living thing, in terms of metabolism and thermodynamics and things like that. But the focus on how selection has crafted those things has come much more recently.
Marty Martin 24:36
I don't want to get too far off page and Cam I know, you have a lot of questions too. But David, you use the word a second ago, I have to ask you to unpack. You said that organisms are agents in the world. We've talked a ton about agency. Did you use that deliberately or what do you mean by agent? Definitely not in a mystical sense, I know that.
David Queller 24:56
Things that have an agenda, but that's just pushing the word along a bit farther. Things that act with with purpose in the world, although it's not true purpose for most organisms, but they act as if they had purpose as a result of natural selection.
Marty Martin 25:13
And so your your writings about organismality have been focused on cooperation. Is there some reason that cooperation takes primacy, like over agency, or apparent agency? Why is it that cooperation has been the cornerstone of most of the research and understanding, you know, this level of biological organization?
David Queller 25:36
Well, we’re the biologists who study cooperation, so maybe that's, maybe that's
Marty Martin 25:41
So did you back into it that way?
Joan Strassman 25:43
No but I mean, agency to ask what an organism is, you have to kind of deconstruct it and look at, you know, if you want to study, what's an organism, you're not going to start with whales, are you? You're gonna start with something on the board? Or you're gonna start with slime molds? Or you're gonna start with with something where they're at the border of is it an organism or isn't it an organism? So what brings it together is cooperation. And that agency kind of goes without saying, because if you're cooperating, you're cooperating towards a goal. And that's the agency and-
David Queller 26:27
You can't have agency if different parts of you are trying to do different things.
Marty Martin 26:31
Yep okay.
Joan Strassman 26:32
So as far as cooperation, you know, we went to grad school in the, in the late 70s, for him, early 80s. And these were cooperation was one of the big questions of our time.
Cameron Ghalambor 26:49
Well, now that we're talking about organismality. I'm curious if you think that just thinking about cooperation and conflict and how it's resolved, is sufficient to explain complex organisms, like, can we get there just with that type of evolutionary theory? Or do we need more? Is there? Are there other sort of emergent properties that come out of- You know, once you have this complex system.
Joan Strassman 27:22 We're good and evolution does not need everything?
Cameron Ghalambor 27:28 Okay. I don't think it does, either. But I'm but I'm also wondering what other types of-
David Queller 27:32
There are, there are certainly additional questions. I mean, organisms are, even a bacterium is it's an incredibly complex system of feedbacks, and then feed forwards and so forth. And you know, how that works is an important part of how organisms work. So no, I don't think we have a lock on all questions about organisms and we’ll talk about cooperation. But of course, that's what they're doing when these networks are evolving, and so forth, are evolving to be cooperative.
Cameron Ghalambor 28:02
Yeah, you mentioned the feed forward loops. Something specifically that I was interested in is like a process like homeostasis, where the organism, or the system becomes sort of self-regulating that wa. Obviously, again, you know, systems that are not as good at maintaining homeostasis as others are going to be at a disadvantage. And so maybe that falls still within the general framework of, you know, standard evolutionary theory.
Joan Strassman 28:34
To me the big change that's come in the last few decades, is increased ability to understand mechanism. So it's not that the evolutionary theory needs change, it's that we can get in such better detail at the mechanisms we can get at the genomes, we can see what genes are active, we can see what they do. So a lot of the the new stuff, the new symposia, I see at meetings and things like that have to do with mechanism. And I count genomics in mechanisms. But the other really big new area, that you know, when I was first a grad student was not big at all is conservation. I mean, we are trying to put what we know about organisms to slow down this great extinction. And I think that that is it's a huge concern. And there again, both theory and mechanisms become important.
Cameron Ghalambor 29:41
I agree. It's it's an interesting sort of line to walk because on one hand, I see like, if you, for example, embrace quantitative genetics and take sort of a statistical view of evolutionary change. You don't really have too worry much about the mechanism, you know, kind of keeps things at a level where the mechanisms aren't necessarily that important. But then obviously, you know, if you, if you take a more molecular genetic perspective on patterns of evolution, then then the mechanisms become really, really, you know, central. And it seems like we're, we're still kind of, you know, depending on your flavor of evolutionary biology, you either kind of embrace one side or the other. And I know that the gulf between the two is sort of getting smaller and smaller with each day. And I guess I you mentioned, like how that maybe has influenced your own work. You've also become, I think, a lot more molecular, in your, in how you've approached your questions. Is that is that a sort of a fair assessment?
David Queller 30:51
Oh, to the extent we can, but we're not molecular biologists, so. We have moved in that direction. Certainly, I'm doing things that are more genetic and more molecular.
Joan Strassman 31:02
But the first big thing we did together was using molecular markers for looking at genetic relatedness. I really am a believer in understanding the organism. And in knowing the natural history and working in the wild, or on wild clones, whenever possible, or organisms. And I think a lot gets missed if people don't have sort of a really basic idea of the biology.
And I can tell you a story about that that kind of goes against us, and that is, there was a time when we were going to start working on stingless bees. And we had worked on wasps for for many years, we knew wasps really well. We were working on a grant proposal on stingless bees. And we had a new grad student who had worked on stingless bees before. And we had her read our proposal for us. But at one point, she, you know, she looked at us and she said, Joan, Dave, you're talking about seeing, but these are stingless bees, they are completely in the dark, they are underground. And so, you know, that's a pretty basic thing. So and it didn't, you know, didn't really impact what we wanted to do. But things were going to be about vibrations and smell, and not about seeing. And so that's just a tiny example of the importance of really knowing your organism. We did make a huge jump from wasps and bees to microbes, but we've kind of stuck with the one system for the last 25 years. And we do know our organisms.
Marty Martin 33:07
Just want to draw attention to a couple of things that you were saying there it's not I think only the organism that you're emphasizing is the organism and its context and its evolved context. So for these dictyostelium, I mean, presumably, you could have grown those up generations ago, and just kept them around in the lab. And maybe they adapted to the lab, that's going to be a very different organism, then you get in a field trip to your backyard for fresh, new, social ameobae. But before I go too much into the details, tell us about dictyostelium. I was a graduate student at Princeton, and John Bonner was just down the hall from me. So I didn't really know very much about his work until I left, unfortunately. He was just the friendliest guy in the world. So how did you start working on this organism? And why is it so fascinating? Tell us about it.
David Queller 33:57
Why did we start working on it? There were a variety of reasons. One was, you know, we still had questions to pursue and social insects, but they were, it felt a little bit as if we were doing variants of the same thing over and over again, didn't want to continue doing that the rest of our careers, there was the appeal of being able to get a bit more mechanistic, even though we don't have that kind of training to go really deep that way. Because dictyostelium, they were in the process of sequencing the genomes, back in the early 2000s. There were methods for transforming them and so forth. Another reason is that we had a graduate student who was casting around for a project, he was a graduate student from China, did not have much background in ecology and evolution. And that became more and more clear as things went on. And we thought, well, you know, what's a good lab project for this guy to do and sort of settled on dictyostelium.
Joan Strassman 34:54
Some other kind of social things are I mean, Bonner wrote a popular book on I think culture and animals. And so basically every every social insect person knew about dictyostelium. There was a point at which I just thought, boy, we've had all these ideas about looking at dictyostelium, and who's the atruist in the stock. We are going to feel really silly if someone else does it when we had thought so hard about it.
So I discovered there was a listserv that that there was dictyostelium community and there was a listserv. And so I started posting questions. I did not realize at the time that the entire community of hundreds of biologists all worked on one clone, and it's, you know, a few descendants. But at that point, one person had a collection of wild clones, which he offered to give us. And I declined, because, you know, we weren't really ready to do anything with them. But then he said, he was headed to Australia on a sabbatical, so it was now, you know, in a year or more. So we got these clones, and they, they came in little vials of silica gel with spores in there. Anyway, so we started playing with them. And the first most basic experiment, which we did was to simply see how the two clones, if we mix two clones together, how they were represented in the stock versus the spore, we were able to design microsatellite, loci primers simply because the genome was sequenced of the earlier ones, I had had that, you know, make libraries and probe them, do all that stuff, didn't have to do that. First paper came out really nicely and published it in Nature. So we thought, Oh, this is easy.
David Queller 37:00
We should maybe back up for your listeners and explain what was so interesting about dictyostelium, for us and for other social insect people.
Cameron Ghalambor 37:07
Yeah, I was gonna I was gonna ask, if, especially because Joan was mentioning the importance of natural history in the organism, if you could give a little bit of just a brief description of the of the natural history and why it is such a great model for studying cooperation and conflict.
David Queller 37:24
Yeah, so dictyostelium is an amoeba. And so for most of the time, they are single celled, and they have these little pseudopods and they crawl around looking for bacteria to to engulf. But the interesting thing with respect to sociality happens when they starve, they eat up all. If they eat up all the bacteria in a local neighborhood, then they start signaling to each other. And this is one of the things that John Bonner studied. They secrete Cyclic AMP, and they attract each other into these, I'm gonna say large mounds, but first, they're composed of microscopic microscopic organisms to produce a multicellular entity with perhaps 10,000 Or 100,000 cells. And then this can develop into a slug which migrates along up through the soil to get to the surface or along the soil surface to find a good area to produce a fruiting body, a multicellular fruiting body. And the fruiting body consists of a long stock, about 20% of the cells in the aggregation die to produce the stock. And the rest of the cells become spores at the top and get dispersed, hopefully by passing insects. So again, you've got you've got the problem of altruism there. Why do these 20% of cells die to produce the stock, when that seems to take them out of the out of the natural selection game.
Marty Martin 38:47
So that whole slug when it becomes the fruiting body 20% of stock 80% is spores?
David Queller 38:53
Roughly speaking, yeah. So John Bonner had been studying this system for chemotaxis. And also for development. It's a relatively simple developmental system. So one of the attractions that drew us to working on this organism, there's already a community of people working on it.
Joan Strassman 39:10
And they were so friendly. And this is just so important in science. I mean, the first meeting we went to, was a couple of years after we started was in 2000. It was in Scotland and there was one person in particular, Rich Kessin, who just was determined to help us in any way possible. He was Associate Dean of the med school at Columbia. He would take my phone calls at any time. When we went for our first field collection, he came along. He stopped everything, came along. So so it just, you know, you hear lots of things about science, and competitiveness and all of that and that just It just hasn't been our experience with the dictyostelium. And they have, they have annual meetings that are just one session, you know, at first we would go to the talks, and we just wouldn't understand anything. But we would just sit next to someone, and they would just explain what was old, what was new, what was controversial show what might be of interest to us. And it's just, you know, this is what makes science so much fun is just just these great people willing to take their time to help. So it has just been really fun.
David Queller 40:39
There's certainly the competition element out there as well in science. And that's one of the things that makes it so interesting. It's like the social behavior we study. It's a mixture of cooperation and conflict. And humans are so good at that, trying to negotiate that.
Marty Martin 40:53
So Joan, tell us about the Nature paper that you mentioned, now that we have the natural history down, when you mix those two clones, and we have this 20/80 problem, what were the results?
Joan Strassman 41:04
It's always good to kind of know what your options are. So we figured, when we took populations of cells from the two clones, and mix them together, and then got fruiting bodies, one possible outcome was that they wouldn't mix at all, and each fruiting body would be clone A or clone B. Another option is that they mix, and they're completely cooperative so that the percentage of clone A in the spores is the same as in the stock. And then, okay, that's kind of boring, then the third option is that they mix and one clone cheats the other getting into spore and not stock. So the slug, before they become a fruiting body, they become a slug that moves towards light, and they're visible, they're about the size of a grain of rice. And the front part becomes stock. So we took the front part and genotyped it and took the back part and genotyped it. And we found that for about half of them, one clone would cheat the other. And so one clone would be almost entirely in spores, and the other would be more in stock
Cameron Ghalambor 42:26
Was it always the same clone? Or would the identity of the clones change between the different replicates?
Joan Strassman 42:33
If I recall correctly, we did in that study, we did 20 independent pairs, did we?
David Queller 42:41
Something like that, yeah.
Joan Strassman 42:43
Yeah. So that study wouldn't answer that question. Another study we did with maybe seven clones, where we made a, you know, a hierarchy. And we found yes, there wasn't a dominance hierarchy, where some clones consistently beat the others. And that was replicated by another lab, and they got a similar, but not identical, hierarchy. As we've moved on in the field, that's not an angle that we have particularly pursued. I mean, if there was one that always won, it would take over. And it seems like there's a lot of other things going on, in the populations. And, you know, there's recognition genes, there's how they're distributed in nature. Usually, in one spot, there's just going to be one clone, so they don't mix all that often. But they mix often enough. You know, we found what we call war genes that are only turned on when they're in chimera. Yeah, there's just, it's kind of like a little wasp colony, where instead of taking a year to develop, it takes three days. So we've really been able to do an awful lot of different things. In fact, we've done so much that we've kind of moved on from looking at the within species stuff and spent about, I don't know, 10 or so years, looking at mutualisms with bacteria that we figured out and now we're looking at dicty as a predator prey system.
Marty Martin 44:27
So tell us more about where you find them in the field. You said that clones tend to occupy one region, but there's a conflict that does happen occasionally. Aren't these almost everywhere? I mean, they're incredibly common, generally, right?
Joan Strassman 44:41
So socially amoebae you will find anywhere if you pick up some soil. Dictyostelium discoideum has an odd distribution. It's found in the Eastern US. We found it in St. Louis and Houston, but it's generally considered to be east of the Mississippi. The place it's been studied the most is Mountain Lake Biological Station and the Smokies. And we've studied them a lot in those places. It's also found in Japan and the coast of China, and has been found in India, I think. But there's lots of other species that are that are found elsewhere. The thing that makes Dictyostelium discoideum, particularly amenable to study is that when they aggregate, and form a slug, all of those cells are totipotent, and they crawl along, looking really like a regular slug. Whereas a lot of species, when they formed that slug, they then make an anchor at the ground there, and they start making a stock right immediately from that point. So questions about commitment to becoming spore or spore stock are different.
David Queller 46:09
But in asking about the sort of population biology and ecology, of these things in the wild, that brings up an interesting point, which is that although we move to working on dictyostelium, because of its many advantages, especially in the lab, studying a microorganism in the field is really hard. You can't go out there and watch them the way he would do with, you know, hippopotamuses or something like that. And so the amount that we know about what happens in the field is, is pretty limited, and it's going to be hard to move forward in that way. I mean, one of the things we do know that Joan alluded to, is we could go out in the field and find one of the places where fruiting bodies are produced are on deer feces. And so we could actually find individual fruiting bodies, bring them back to the lab and genotype them. And we found that most of them were clonal consisting of a single clone, but some of them were chimeric. So we know there's some kind of population structure out there that enables them to interact with relatives most of the time. But, boy, there's a whole lot we don't know about what they're doing in the field.
Marty Martin 47:13
Yeah, when they're when they're chimeric, are they chimeric the same species, different populations? Or the chimeric species too?
David Queller 47:20
What we found in the field was chimeric the same species. But we have found in the lab that you can mix two different species.
Joan Strassman 47:28
No, you're forgetting Chandra's work in Houston where we founnd a mixture there we had D. discoideum. Was chimeric with D. purpureum, which is kind of like a human being chimeric with a fish.
David Queller 47:44
Separated for a lot of millions of years.
Marty Martin 47:47
Yeah. Wow. Wow.
Cameron Ghalambor 47:48
And so when the different species get together, are the dynamics of the of the sort of lifecycle all the same? Or do they do something fundamentally different?
Joan Strassman 47:58
So what we found was the width D. discoideum and D. purpureum, the fruiting bodies were never intermediate, phenotypically, they were either looked like purpureum
David Queller 48:10
Which is purple.
Joan Strassman 48:11
Yeah, or they look like discoideum. And when they, when they looked like purpureum, there were very few discoideum cells in there. When they looked like discoideum, they could handle you know, 20 or 30%. of purpureum themselves in there.
Marty Martin 48:32
So I'm really fascinated by discoideum. I work a lot on house sparrows. So organisms that are very broadly distributed have always been compelling to me. What do you mean, are there things with discoideum that you've studied that sort of make some sense of why it has, I mean, presumably a broad geographic distribution based on what you were saying a minute ago, but maybe I'm making a bad assumption. Is it that much more broadly distributed than the others? And are a lot of them narrowly distributed? Is there some interplay in all of these things? We're making this up?
Joan Strassman 49:01
So dictyostelium has been divided now into like five or six genera. And the giant genus with D. discoideum is sort of the big aggressive, easy to find species. And I would say if anything, D. discoideum, is less common.
David Queller 49:21
It's probably in the middle of the range of between very common ones and rare ones.
Joan Strassman 49:25
But if you are in northern forests, northern cool forests, like you know, Mountain Lake and stuff, it's it's pretty common. It's not hard to find. We've collected from, you know, Houston, St. Louis, all through, you know, Indiana, Illinois, and then up into the northeast, we've got a collection of 700 clones
Cameron Ghalambor 49:55
I'm super curious about the that that sort of like spatial scale over which you see this kind of genetic variation, like you said that usually when you go to a given site, it's just one, it's often it's just a single clone. But-
Joan Strassman 50:11 By site, I mean pinprick. I don’t mean site.
Cameron Ghalambor 50:15
So micro micro site.
Joan Strassman 50:19
I mean, if you take a straw, and you collect about a fifth of a gram, you are likely to get three or four different clones of D. discoideum.
David Queller 50:33
We did have one study in which we discovered a really weird phenomenon. In a cattle pasture in Texas, we collected D discoideum. And they were all identical across quite a large range. And we haven't seen that anywhere else. I don't think it has something to do with agricultural practices or something.
Joan Strassman 50:53
So I led that field trip, we had three new undergrads. And I like to take people in the field to start with. And, you know, we went under the fans, and they're Texans. And they're like, you just don't do that in Texas. But it was like, so wide open. We weren't that close to the fence, but we were in the very open area. And so we were doing a transect with our straws and everything and also collected from some cattle piles and stuff.
And so there were there was a herd of cattle at the far end of the field, as we were starting. And as we were taking our you know, 30 samples or so, at one point, they started coming thundering towards us. And the the undergrads were just all freaked out. But I looked and I saw there was like a feed barn nearby. And they I said, “Oh, they're gonna turn and go to the feed barn.” “No we've got to go back to the fence.” I'm like, “No, you don't have all your samples.”
So we got back to the lab. And we we cultured these things, and they were just teeming with D. discoideum. It was just we had never seen anything like the numbers. I mean, yeah, you just phenomenal. And then we went back a couple months later, and they were gone. And I'm guessing it was an interaction with the cattle and the Ivermectin, which will kill D. discoideum also. But then, one of our grad students at the time, Owen Gilbert took over that study collected from a number of other local cattle pastures and never found it again.
David Queller 52:45
In terms of them being successful, and I guess they are successful. That kind of ties into our latest research effort, although our main questions, not to answer why they're successful. It's relevant to it, though. We're starting to look at dicty as a predator. And one of the things that might be the thing that they do is go around and gobble up bacteria and fungi and things like that. And they are, I agree, they're super generalists. They can eat a huge number of different bacterial species. And if you sample bacterial species from the soil, which we've done, culture some out, they can eat most of them. And given there might be 30,000, bacteria species and a gram of soil or something like that, that’s a lot of species. So we're curious in the questions about how they do that. But presumably, other other social amoeba are doing that, too. I don't, I suspect they're not special in that regard.
Cameron Ghalambor 53:50
Kind of back to the natural history. So you have these these amoeba that are hanging out, they end up depressing the local food resources, gobbling everything up as predators. Presumably, some individuals are in better condition than others. And I think you've written about this. And so then, they formed the slug, and the slug starts to move, which must require some energy. You know, which, which the movement I assume other people have studied this, but I found that part by itself so interesting, because, you know, when you teach undergraduate zoology and you talk about like, the, you know, the mechanisms of locomotion and the coordination of muscle and, you know, various things, you know, here are these cells that just all of a sudden got together and now show coordinated movement. That by itself is fairly amazing. But they're also using a bunch of energy and so the variation among individuals in energy spent either during locomotion or the condition that they went into to form the slug, that does have some implications for who becomes the stock versus the fruiting body. Is that right?
Joan Strassman 55:10
Yeah, I mean, we've done studies where we've raised some individuals from a clone on a poor diet and others on a good diet, and the ones on a good diet are more likely to become spore.
David Queller 55:23
Which makes sense if there's a competitive element to it, as you would expect, if they're sometimes chimera.
Cameron Ghalambor 55:29
Totally yeah. Well, you know, kind of back to Joan's point about, like, things getting complicated versus simple. I mean, I think that really speaks to also some of the context dependency of, you know, like, you can make the mathematical model. But you know, when you go out into nature, and you study the natural history, you're like, well, you know, it depends on what condition the individual is in. And so that's something that needs to also be you know, that that kind of dependency needs to be part of the, the math I guess that underlies, or, you know, thinking about under what conditions, would we expect one clone to have an advantage or one to be able to cheat?
David Queller 56:11
I guess, yeah, right. They're all starving, of course, they've run out of food, but some are starving more than others. So that matters. And in fact, they're undergoing autophagy, as they're developing, at least the stock cells I don't remember about spores are probably getting rid of some of their stuff, too. So they're, they're in trouble. And they're, they're working to get out of there.
Marty Martin 56:30
I never thought about before, if they're starving, and they get into the slugs, how do they ever do this happily, anyway? I mean, they're so desperately hungry, why aren't they eating each other?
David Queller 56:38
We haven't thought about that much. One answer would be you're you're usually with your relatives. Another might be maybe they don't have that capability. There is a species of dictyostelium called Dictyostelium caveatum, which eats other amoebas. But it's only been found once and have never been found again. But it is it is a thing that is biologically possible, but maybe not for these species, I don't know.
Joan Strassman 57:05
But the other thing is, if you're starving, and you've evolved to want to get out of the spot where you're starving, so becoming a fruiting body and making hearty spores that are sticky and will stick to a passing invertebrate is evolutionarily a better strategy than just eating your neighbor, which only saves you about 10 minutes.
Marty Martin 57:31
Right, right, the next generation versus a full belly or short period of time. Yeah.
David Queller 57:37
One of the interesting questions that hasn't been answered, I said, you'd be eating your relatives, and that wouldn't be good. But in fact, when you're joining together with the relatives, and you know, at least this pre-stock cells are undergoing autophagy, it would be possibly useful for those cells to digest themselves in order to feed the spores. We don't know about that yet. I mean, maybe it would require tracer studies or something like that. That's a possibility that they're actually dying and allowing themselves to be cannibalized, essentially.
Marty Martin 58:07
Okay. So, as promised, I'm going to zoom out a little bit and ask you whether this lifestyle you said 100 species of dictyostelium, and the five genera now, is this lifestyle, very common, and we don't know about it. And I'm asking that, to try to understand how you see dictyostelium in the work that you've done to relate to the origins of multicellularity on Earth. I mean, how much we know about how many different paths by which that happened? I'm sure we don't know very much. But how do you view this taxon as a model organism that way? Is it that this approach is general? Or is this a one off kind of thing for dictyostelium,
David Queller 58:49
There are other organisms that are similar and in the sense that they aggregate together and produce a fruiting body. Sometimes, I think with altruistic sacrifice, probably not too many independent cases of that. Depends upon what you mean by the lifecycle, if you mean cells aggregating together to produce a multicellular body, I think there's a recent paper and I didn't know the author, so I don't remember it, sorry. Surveying instances of multicellularity, aggregate of multicellularity and came up with, if I remember about 40 of them. But they take different forms. They're not all exactly like dictyostelium. And they are perhaps overlooked because they occur in taxa that most people are not familiar with. And the organisms that we are familiar with, are not aggregative multicellular, they're what we call clonal multicellular start from a single cell that divides into many genetically identical copies.
Joan Strassman 59:57
So another thing what I think is important is that dictyostelium is a really old genus. And one way we can think of it is aggregation, which allows the opportunity for exploiters or cheaters to come in, does not result in such a opportunity for complexity. So in the, you know, billion years, animals have formed all these fancy different forms and the dictyostelium have only a few different cell types. You know, they're not necessarily less successful than us. But they certainly haven't evolved the biological complexity of of animals.
David Queller 1:00:49
So as a model system, they could be a model for other organisms. But even if they weren't, and even if they never mixed in nature, suppose they were always clonal in nature, I still think they're an interesting model system, because you can mix them in the lab and see what happens.
Marty Martin 1:01:06
Yeah. Dave, you said something that reminded me, I have to ask you, are you familiar with Mike Levin's biobots? No. Okay, so he's a professor at Tufts, we've had him on the show twice. He has taken embryonic cells from frogs, I can't remember it's an epithelial thing and some other stuff. And neural crest, yeah. He's basically plopped these things together, and created brand new forms of life, that are quite agential. They're able to run research gradients and solve puzzles and do all of these amazing things, even though they're just, you know, two almost randomly chosen forms of cell types that have been functionally put together.
David Queller 1:01:40
That sounds really interesting.
Marty martin 1:01:42
Yeah, so maybe that's for another time. But it's it's super intriguing. Using that same evolutionary history, those cells, in principle have always had relationship among each other. But in this particular kind of functional relationship, it's a brand new organism.
Cameron Ghalambor 1:02:11
So I started off as a ornithologist, so I'm still an ornithologist at heart. And a lot of my PhD research was spent in a in a blind. watching parental care of birds. And, you know, my roommate, as a grad student was a plant molecular geneticist, and, you know, he would poke me and make fun of me all the time for saying, like, you know, do they give PhDs for people that just like, study and watch birds? So, you know, even though I had a bit of a inferiority complex about it, it was invaluable, I think, for me developing as a scientist, and just to be able to block everything out, and just watch birds and their behavior. And it got me thinking a lot about, you know, bigger topics, like phenotypic plasticity, trade-offs between, you know, parents and offspring and parental care.
So I just at with that preface wanted to say that I'm a, I'm a very big fan of the idea of slowing down, and just watching birds and appreciating the details beyond just checking bird name off of your list. And so, I didn't know that, John, you were a bird watcher, and, you know, I knew you from your research papers. And so how did you get into birdwatching? And and what was the what are the origins of the kind of the concept of slow birding?
Joan Strassman 1:03:49
Well, so when scientists write books, they tend to be based on their research, and my book’s not like that, my book is based on my teaching. So I've taught animal behavior since 1980, as a faculty member. I did lots of different things over the years, but at one point I decided, what these students really need is something very freeform that really lets them figure out what a hypothesis is and where it comes from. And so I would take the class out and show them the birds and the first assignment was to spend an hour and a half watching each species, take notes, count, whatever you can count, and then tell me how the birds are using time and space, how it differs between the sexes, and what you want to know about for the next time. And they would just have to develop through the semester, coming up with things to look at.
So my idea is that the principles of Behavioral Ecology, which has always been what we are most interested in, are really best taught with birds. You know, wasps? I don't think so. Amoebas? Not really. If you just asked someone to really watch the birds, it's really quite amazing. Anyway, so that's where slow birding was born. And I, you know, ever since I heard of the slow food movement in Italy, and the idea of, you know, appreciating the local, I wanted to write this book. And, you know, took me about 20 years before I finally actually wrote it. You know, the idea is simply to encourage people to get out and watch the birds. And so that's why every chapter has exercises at the end of things that you might watch. One of my praises I'm most happy for the book was one of my colleagues said: “Hey, Joan’s written a Behavioral Ecology textbook here.” You know, I did try to cover all the various topics and things, and it's just sixteen birds and some place stories. And it was a lot of fun to write.
Marty Martin 1:06:21
Oh, that's wonderful. I haven't taught ornithology before. But my colleague is offering it right now have to check and see if he's considered that. It's always been a frustration of mine to offer these canned lab sorts of classes, because they're so removed from, you know, what the process of professional science is. So it's really great to hear that that kind of format is going to be big payoff.
Joan Strassman 1:06:42
And you know, it's actually a lot easier than all the other labs.
Marty Martin 1:06:49
Yeah. Breeding all those fruit flies, pouring all the agar plates and things.
Cameron Ghalambor 1:06:54
Yeah have you? Have you gotten any, like personal feedback from anybody who has read the book and had a transformative experience? Like, I'm imagining, like the person who was into bird watching, but you know, would see the bird and then check it off its list and then move on to the next thing. Who might after reading the book, spend a little bit more time watch, watch what the bird behavior is? And have you had any, like personal feedback like that?
Joan Strassman 1:07:26
I almost get more from people who were too intimidated to become birdwatchers, who then realize, Oh, if I can just watch a, you know, a cardinal and a house sparrow, maybe that's a good start. I don't think I've ever reformed any listers. And in some ways, it's not really my purpose. It's just, you know, I mean, I, I read these bird books like candy and there's so many of these guys that go on these, you know, year long trips, and I, you know, I read one of these books, and I won't say who it was by, and I read the whole book, and I don't think in that book, there was a single story about a bird. There was lots of stories about finding birds and about trucks falling off precipices and mud and mosquitoes and discomfort and finally seeing the bird. But there wasn't a single story of bird X does behavior Y, and I saw it.
Marty Martin 1:08:35
So you know, you're writing the book on the mixed species flocks? Have you considered maybe together writing a book on organisms? Is that in the in the plans?
David Queller 1:08:47
The topic has come up, I don't think it's on the front burner. Could happen one day.
Joan Strassman 1:08:52
The book, I'm writing is social lives of birds, and mixed species flocks is one chapter. I keep trying to entice him with different ideas of kinds of books to write.
Marty Martin 1:09:06
Well, good. So thank you so much for the conversation. We've taken a bunch of your time. I want to give you the chance, though, to add or say anything that we didn't prompt you with a question? Is there is there anything we didn't cover that you want to make sure we hit?
Joan Strassman 1:09:19
You know, if you're talking about cooperation and conflict, and sort of the evolution of kin selection and things, it's really everywhere, and it can inform us in all kinds of ways. So one example thatI like to talk about is something as personal and intimate as the human placenta is actually quite a battleground for resources. And it's really only a battleground because the mother's interests and the father's interests are not the same, because the mother and father are not necessarily going to be the parents of all of the babies, the mother bears. So there's just all kinds of really interesting conflict in the placenta with the with the fetal genes, causing the fetus to take more nutrients than the mother is selected to provide. And when these things go awry, that you know, it puts the baby in danger. And understanding kin selection and conflict from an evolutionary point of view, can help us understand and develop better treatments for mothers and babies.
Marty Martin 1:10:50
Yeah, we just talked about that in my evolutionary medicine class last week preeclampsia and paternal fetal conflict. Yeah. The student's eyes got wide. Wow, I never thought I never thought of that before. Well, hey, thank you so much. We really appreciate your time.
Cameron Ghalambor 1:11:04
Yeah, thanks so much. We really do I do.
Joan Strassman and David Queller 1:11:06
Okay, thank you.
Marty Martin 1:11:17
Thanks for listening! If you like what you hear, let us know via X, Facebook, Instagram, or leave a review wherever you get your podcasts. And if you don’t, we’d love to know that too. Write to us at info@bigbiology.org!
Cameron Ghalambor 1:11:28
Also thanks to Steve Lane, who manages the website, and Ruth Demree for producing the episode.
Marty Martin 1:11:34
Thanks to Dayna de la Cruz for her amazing social media work, and Keating Shahmehri produces our awesome cover art.
Cameron Ghalambor 1:11:39
Thanks also to the College of Public Health at the University of South Florida and the National Science Foundation for support.
Marty Martin 1:11:47
Music on the episode is from Podington Bear and Tieren Costello.