Cannibalism (featuring Volker Rudolf)

00:00:06
Speaker 1: I was interested in animal behavior, and for my master's degree, I was studying juvenile smallmouth pass So I went out in the wild and after getting all of the permits I needed, I brought a bunch of them back into the lab and they were like these little guys. And as they were growing up, I noticed that the number of fish in the tanks was going down, and I was totally stuffed. The water quality was great. I wasn't finding any dead bodies in the tank. They weren't like getting sucked into the filters. I was crawling around on the ground trying to see if they were somehow getting out of the tanks despite there being a lid on all of the tanks. And then one morning I walked into the environmental chamber and I was shocked. One of the fish had a giant tail sticking out of its mouth. It had not occurred to me that they were eating each other like one. It hadn't occurred to me because the fish in the tank were pretty similarly sized, and this was not the first time in my life. I was going to be amazed at how big prey items are for these basts, like how much food they can fit into their gigantic mounds, so they were apparently able to eat each other even when they were like pretty close to the same size. But also I was totally naive to how common cannibalism apparently is in the animal Kingdom. I was like, you can't eat your brothers and sisters, but no, absolutely, they were totally fine with that. And that's what we're going to be talking about today is cannibalism in the animal Kingdom. We're gonna mostly be talking about non human animals and it's going to be quite a ride. We're interviewing Folka Rudolph and he'll tell us all about his research in this field. Welcome to Daniel and Kelly's Extraordinary Universe.

00:01:45
Speaker 2: Lone epetite.

00:02:00
Speaker 3: Do Daniel and Kelly's Extraordinary Universe. I'm Daniel, I'm a particle physicist and I've never eaten a human being.

00:02:07
Speaker 1: I'm Kelly Waider Smith. I also have never eaten a human being, no desire to do so, but as an ecologist, I have seen lots of animals eating other members of the same species.

00:02:17
Speaker 3: Well, let's dig into that a little bit more. Kelly, my question for you today is what is the most intelligent animal you have ever eaten.

00:02:24
Speaker 1: Oh, geez, probably pigs because they're super intelligent. I eat meat less these days because ever since I got on a farm and I've started interacting with like cows and pigs and goats and sheep, I'm like, oh my gosh, you all like you have personalities if some of you are very smart. But I gotta be honest, I feel way better about eating chicken because our chickens are so stupid, and I don't feel too bad about eating chicken.

00:02:51
Speaker 2: So anyway, what about you?

00:02:53
Speaker 3: Where are you saying the dumb deserved to be eaten? Is that what's happening here?

00:02:56
Speaker 1: That is not what's happening here. You don't need to extrapolate to the forbidden meal. But I do think chickens, you know, they're delicious and silly.

00:03:04
Speaker 2: What about you?

00:03:05
Speaker 3: I'm not going to answer your question yet, I'm gonna keep pushing you. Would you eat a champanzee or a buonovo if somebody puts a chimp of skull in front of you and flips it open and says, here's a brain delicacy. Is Kelly saying no, thank you? Or are you digging in?

00:03:18
Speaker 2: Hm? I am saying no thank you. Yeah, why am I saying no, thank you?

00:03:22
Speaker 4: Oh?

00:03:22
Speaker 1: So much introspection happening right now? Are there not loads of bonobos in the wild. I don't know their status, so, like one, I don't want to eat anything that's like endangered or threatens or anything like that. But also, I guess I do feel uncomfortable the closer they are to me. And partly that's because, like, there's a lot of zonotic diseases, so a lot of diseases that jump from wild animals to humans, and I guess I would worry that the more closely related you are to those organisms, the more likely something is to jump.

00:03:47
Speaker 2: But I wouldn't have that excuse if it was like.

00:03:48
Speaker 1: A labraze chimpanzee. I still don't think i'd want to eat it. Yeah, nope, I don't know that I have a good logical reason, but my tummy is saying no.

00:03:58
Speaker 3: Well, I'm an una bashed speciesist. I feel like being human is different from being a puppy or a chicken or a pig. And I used to feel like that wasn't fair that you couldn't just say, hey, members of the human species have certain rights that pigs and dogs and whatever, don't. But these days I've come to accept that that's just kind of how I feel, even if it is wrong. And so, for example, I'm happy to eat an intelligent pig, but I wouldn't eat a very stupid person. Okay, you're cool with that.

00:04:31
Speaker 1: Well, trying to figure out what is the logical framework behind? Is it just anything that's not humans as good?

00:04:36
Speaker 5: Like?

00:04:36
Speaker 1: So you still haven't answered. Would you eat the chimpanzee and the bonobo?

00:04:39
Speaker 3: I probably would eat the champanzee and the bonobo. Yeah, exactly, nice clean libraries. Chimpanzee, Yeah why not? I mean I eat pigs, and so let's go all in. They're probably delicious.

00:04:51
Speaker 2: At least you're consistent.

00:04:52
Speaker 1: I recognize I'm not very consistent, which is part of why I shy away from meat all together, because I feel like I haven't quite formulated the framework for what I feel comfortable with and what I don't feel comfortable with. Props to you for being consistent.

00:05:06
Speaker 3: Well, I think it's interesting that a lot of people probably haven't really thought through what they would eat and what they wouldn't eat and why. I remember reading an article about speciesism like twenty something years ago that actually inspired me to become a vegetarian. Made me realize that I was being unfair to really smart pigs because I was giving them fewer rights then I was giving to, you know, not smart humans that I would refuse to eat. It made me feel like, hmm, maybe I just shouldn't be eating any creatures at all. And you know that lasted for like ten years. I was a militant vegetarian for like ten years until I had a son and he was very obviously a carnivore, and we lived in France, where if you ask for vegetarian lunch they give you like chicken or fish. So it didn't last that long. And these days I just feel like, yes, there is something special about being human.

00:05:51
Speaker 1: For a while, I was some special kind of vegetarian where I like mostly wouldn't eat meat, but if I knew that the animal had been treated mainly its whole life and was euthanized humanely, so it was a cow that lived on this beautiful farm and had free range and had buddies.

00:06:07
Speaker 3: It could paint twice a week and do arts and crafts and.

00:06:09
Speaker 1: Stuff yoga class on Wednesdays. I would make exceptions for that. And since I was in grad school at the time. I couldn't afford to do that very often. So it was like I'd have, you know, one meat dish a month where I would go and pay for that. And Zach, my husband, likes to laugh because the thing that ended up breaking my like vegetarian streak was I just couldn't stop craving Arby's beef and cheddars.

00:06:33
Speaker 2: Can't witches, which is just the lowest quality food ever.

00:06:37
Speaker 1: But like my grand student heart just had to have one, and that was the thing. Like I had one, and then I was like, well, I've broken it, and then for a while I just ate what I could afford, which was Arby's because I was a grand student. Anyway, I've always had a complicated relationship with meat, I guess.

00:06:52
Speaker 3: And all of these behaviors are not rational, right, These are people's emotional feelings about what's right and what's wrong. What you grew up with, you know, I grew up not eating the shellfish at all, and so like I think shellfish are gross, and you cannot catch me eating shrimp. I'll eat a chimpanzee. But like shellfish, if it's icky, it's like insects of the ocean. I'm as likely to eat a cricket as I am to eat a shrimp.

00:07:12
Speaker 2: I am more likely to eat a cricket than a shrimp.

00:07:14
Speaker 1: I mean, so you kind of like deep poop the shrimp before you eat them, Like, I know that's just gross.

00:07:20
Speaker 3: Are gross? Exactly? And so on today's episode, I'm looking forward to exploring that line, like who eats who? And why do they do it? Why don't we eat our neighbors kids or should we?

00:07:32
Speaker 1: You know, I think law probably plays into why we don't eat our children's kids.

00:07:36
Speaker 3: Why is the law that way? And should it be that way?

00:07:39
Speaker 6: Right?

00:07:39
Speaker 3: Should we have a reform movement that says cannibalism is actually okay?

00:07:43
Speaker 2: You are asking all the big questions, Daniel.

00:07:46
Speaker 3: This is not my field, and so I feel totally comfortable just like asking the big dumb questions.

00:07:52
Speaker 2: Well that's great, I love that, all right.

00:07:54
Speaker 1: So, speaking of big dumb questions, I asked, how common is cannibal and non human animals? And have you ever seen it in nature? So I asked this to some of my friends. And the big dumb thing that I did was I accidentally mistyped my friend's number in because like it was somebody I hadn't messaged for a while, and I said some questions about cannibalism to like random person who's probably very confused.

00:08:17
Speaker 2: They never responded by like said the questions, and I was like.

00:08:19
Speaker 1: Oh gosh, I'm sorry, prom number, I'm a scientist. This is for like a science thing, and uh, like I got all awkward and I was like, I need to just stop texting this person. Let the more texts I send, the more crazy they think.

00:08:30
Speaker 2: I am.

00:08:31
Speaker 3: Well, at least you gave them a funny story that they can tell at their next dinner party, which I hope is not a cannibalistic one. And if you would like to give answers to random questions, maybe about cannibalism, maybe about particle physics for future episodes of the podcast, please write to us to questions at Daniel and Kelly dot org.

00:08:47
Speaker 2: And now let's hear from Kelly's friends.

00:08:50
Speaker 7: I have definitely heard of animals being cannibalistic. I remember being in the fifth grade and I had gotten like a tink of fish as a birthday peasant, and I had one fish that attacked all the other fish and ate them, and it.

00:09:09
Speaker 5: Was a little traumatic I am really not sure. I don't think that it's terribly common in the vertebrate world, but maybe more common in some invertebrates for some reason. I'm thinking among the insects possibly. I do think I have seen, especially some insects cannibalizing other insects that I believe would be the same species.

00:09:34
Speaker 4: I think it is pretty widely you know, out there, So I think like insects and even like some amphibians and things like that do it because it's one of those things where you want to eat no matter what and survive. I've also heard about bears, so bears will do it to other young cubs from from breeding mothers because that will then induce them into like a breeding cycle so that they can then become the father, et cetera and pass on their genes.

00:10:09
Speaker 8: I think this is probably pretty common in the animal kingdom, but I mostly associated with parenting. My understanding is that it in my brain anyway, is that it comes up most often in situations where like a cat or a rabbit or a dog like is really kind of distressed, maybe like whatever. The dog equivalent of postpartum depression is, I don't know, and they eat their offspring.

00:10:43
Speaker 9: I would guess that cannibalism is kind of common among fogs and snakes and insects, possibly fish. I do remember that I had signed these fighting fish that gave birth to babies, and you had to quickly separate the babies otherwise mom and dad would eat them.

00:11:05
Speaker 6: Yeah.

00:11:06
Speaker 9: I guess if the bud dies in a colony, they're not just gonna.

00:11:10
Speaker 4: Give it a burial.

00:11:11
Speaker 9: They'll probably just repurpose all it's nutrients or something. I'm just guessing.

00:11:16
Speaker 3: How do you feel about these answers, Kelly?

00:11:18
Speaker 1: I thought that my friends gave great answers about cannibalism. I also felt like they were really great sports.

00:11:24
Speaker 6: One of the.

00:11:24
Speaker 1: People, like, I texted in the question and they texted back, I didn't know what to expect, but this is so totally on brand for you.

00:11:32
Speaker 2: I was like, what does that mean?

00:11:34
Speaker 1: But then also, yes, you're right, totally on brand. So no, I thought they were great. It seems like there's this like hypothesis building based on the answers that invertebrates maybe do cannibalism more than vertebrates, because I thought that was like a pretty common theme. I don't actually know if like insects are more likely to eat each other than fish or frogs. I've seen lots of fish eating the same species. But yeah, I thought there were great answers. What did you think? And how are you going to try to connect it to humans?

00:11:59
Speaker 2: This time?

00:12:02
Speaker 3: I thought it was interesting how widespread the answers were. Some people thought it almost never happens, and some people think it's pretty common. I'm pretty curious to know how often does this happen out there in the animal kingdom? Is just humans that awkwardly joke about cannibalism on podcasts? Or is that also something that happens in the fish world.

00:12:21
Speaker 1: Let's learn more about the forbidden meal on today's show, We Have Folk Are Rudolph. He's a full professor of ecology and evolutionary biology at RICE. He's editor in chief at The American Naturalist, which in my field, that is a huge stinking deal. He is self diagnosed with scientific add He studies stuff like a penology, which is like the timing of when stuff happens in nature, like when are the flowers blooming, when are the tadpoles turning into frogs?

00:12:51
Speaker 2: And how does that change over time?

00:12:53
Speaker 1: He also studies like temporal dynamics, you know how that stuff is changing across the United States, for example, and climate change. But we're not talking about any of that today because a few years ago he was studying cannibalism and I've never forgotten how awesome that is. So we're going to talk to him today about cannibalism.

00:13:13
Speaker 2: So what got you into cannibalism.

00:13:18
Speaker 3: And what do your parents think about that?

00:13:20
Speaker 10: So I got interested in doing grad school. I was looking for a thesis topic, and I did some reading. I was generally interested like in the role of size and like mediating interactions, and at some point it came across some work in cannibalism and fish, and they were really curious about kind of like the role of cannibalism and regulating the populations. And then this had bigger consequences for the entire ecosystem because this was like a top predator and they got this interesting dynamics that were all driven by cannibalism, and so like look more into it and realize that there is not much known about cannibalism, especially ecological consequences of it, and most have been tweeted this kind of like weird thing that happens, but we don't want to talk about it kind of like, but it was really interesting to me, and so like I focused, I wanted to know more about the ecology of it, kind of.

00:14:10
Speaker 6: Like what's driving it.

00:14:11
Speaker 10: We've now been looking more into like the evolution of it as well, so it's been more like a slow organic process.

00:14:18
Speaker 1: So as a parasitologist, people always want to tell me about the time they thought they were infected by a parasite. Sometimes they want to show me photos of their feces. As someone who studies cannibalism, do people try to tell you stories about like, oh, my fish, ate my other fish? Have you acquired many weird stories?

00:14:33
Speaker 10: If I talk about my research, then you should people get stuck on the cannibalism stuff because the most interesting dinner conversation topic.

00:14:39
Speaker 3: People wanted to talk about cannibalism over dinner.

00:14:44
Speaker 10: Yeah, but it's like once we start publishing some more and then especially and then we're going to talk about later this stuff we did on the interaction between comes from disease. I started getting a lot of you know, like media stuff from like in radio shows and other podcasts thing, and nine of those all had to do with some weird human anecdote thing, which is like nothing I do at all or right, but it's like so I got a little frustrating. They're like, okays, like this is not really what I do, but sure, yeah.

00:15:17
Speaker 3: Well, how widespread is any knowledge of cannibalism, Like do people have mostly a misunderstanding of what cannibalism is and how it works? Or is the concept in the minds of the general public pretty much accurate.

00:15:27
Speaker 10: I would say there's a pretty big misconception overall. And most of that so really comes from like our take on like entreprenmdvising the whole thing when we think about cannibalism it so it goes back to the idea that this is something that only happens on the extreme weird circumstances.

00:15:45
Speaker 6: It's not normal.

00:15:47
Speaker 10: I think that's kind of like how most people think, like, oh, there's this week antidote about the shark doing some freaky thing, and like.

00:15:54
Speaker 6: That's not normal.

00:15:55
Speaker 10: And in reality, and when cannibalism is completely normal, it's super widespread. It's everywhere in animal kingdom, And there's why do we take the morals away from it? It makes sense because it's some normal ecological interactions just to predator prey interactions.

00:16:12
Speaker 6: This happens to be like the same species.

00:16:14
Speaker 2: And how widespread is it?

00:16:16
Speaker 1: So I tell a story at the beginning of the episode where my small mouth bass we're eating each other during my master's project, and I was like totally surprised by you know, where all the fish and my experiment were going.

00:16:26
Speaker 2: What other organisms do it?

00:16:28
Speaker 10: I mean, I would say, like, if it's predatory, there's really high chance it's cannibalistic. So most species and other predators are probably to some extent cannibalistic, and then there's some variation and nuanced. But I would say for me that it's like the default. There are exceptions to that that are not cannibalistic, and there various reasons for that. But I'd say the default is kind of like predatory. It's cannibalistic, and there are a bunch of other species that are not even predatory. There's still cannibalistic, right because it can help, but like nutrient deficiencies, the components or just removing competitors from the field, right, So it's all over the place. It's probably one of the most underreported interactions in the animal kingdom.

00:17:11
Speaker 3: I think a lot of people might wonder why cannibalism is so widespread. I think like a naive understanding of evolution, like the one that I have, for example, would suggest that it might be detrimental to the population as a whole. Right, But is it as simple as yeah, but it helps you and your genes or all you care about pretty much.

00:17:27
Speaker 10: Yeah, it's from a in real perspective, it's just another way of getting resources, and you're not doing it to the benefit of the population. You're just trying to increase your own personal fitness. And in many scenarios that's a good option. Right, So you can think of it, for instance, if you're cannibalistic, you can remove competitors from the environment.

00:17:47
Speaker 6: Right, that's like a direct goal.

00:17:48
Speaker 10: Not only do you remove them from the environment, you actually get energy from them on top of it. Right, So it's a double wind situation and the costs are something. Then that's like under which conditions is it not beneficial? And then you come back on like inclusive fitness and kind of like what does it do to your offspring and what's the risk of eating those.

00:18:06
Speaker 3: It's like Google acquiring other companies, right, competitors off the field.

00:18:11
Speaker 6: Yeah, pretty much.

00:18:12
Speaker 3: All right, Well, then I have a question for you about cannibalism that I'm pretty sure you've never gotten before.

00:18:17
Speaker 6: Okay, So I've.

00:18:19
Speaker 3: Heard the argument that on other planets, if life evolves, it's very likely that there will be predators there because beings will chomp on other beings because, as you say, it's a rich source of nutrients. So then my question to you is are you suggesting that aliens are very likely also cannibals.

00:18:37
Speaker 6: That's a pretty good chance.

00:18:38
Speaker 3: Yeah, all right, and I think we have our spinoff movie Alien Cannibals. We'll wait for the first drafter the script from you looking forward to that.

00:18:47
Speaker 6: It's the question I heard before.

00:18:49
Speaker 2: So Daniel.

00:18:54
Speaker 3: And I got the work in Aliens double bonus.

00:19:13
Speaker 1: Okay, So is there a difference between cannibalism if you're the one killing the conspecific you plan on eating, or if you like come across it and it's dead, both of those are cannibalism or does the definition of cannibalism imply that you had to like kill the organism before you eat it or is it all the same?

00:19:30
Speaker 10: So the definition were kind of stuck in bin was like killing in at least partial consumption of a conspecific, So if it's already dead, we would call it necrophagi. As I comment, so we talked about this, so like in the disease perspective, that's like a different dynamic. But I guess so I would usually we can talk about cannibalism and most of the literature in the walls the killing part. But of course, like most terms, there's various definitions of it floating around.

00:19:57
Speaker 1: Okay, all right, so I know that all of us on this call are parents, So what are some benefits of eating your children?

00:20:09
Speaker 10: Interesting choice? I mean, so when you see parents consuming their offspring, right, But for many ways, that's like the thing that usually selects against cannibalism. But there are reports of this and various instances where you have parents eating their offspring. And the example for instance, like in fish, there's an interesting study that came out a while ago where they showed that males that was regarding the eggs for the females, we're more likely to cannibalize the eggs if they thought that they weren't actually the deads, right, so the other dad would swoop in doing like the fertilization process, and if they thought someone else actually fertilized the eggs that would just eat it and do it over again. There's another one where you have scenarios where like parents will consume their offspring, for instance, in case of a disturbance for instance, or like the risk of predation. I think in those cases it's kind of like the idea behind it is the evaluating is, Okay, if some preter comes in, they're going to eat all my eggs, I get nothing. If I eat the eggs, I at least get part of the energy back that invested in it, all right, So it's kind of like a very risky kind of like to lose it all or do it keep some of it? So like scenario which it does happen in some scenarios that's cold, yeah.

00:21:30
Speaker 3: Rather cannibal dilemma, huh yeah.

00:21:33
Speaker 10: But there very few instances where eating your offspring is beneficial.

00:21:39
Speaker 6: I mean, I can not really think of a whole lot.

00:21:41
Speaker 10: Like I said, in most cases, that's what selects against it.

00:21:44
Speaker 6: Don't eat your kids.

00:21:47
Speaker 1: Follow up on that one, we do like a random survey of people before we do an interview to ask what their opinions are on the topic, and one of the people we interviewed said that they thought mostly cannibalism was about eating their young because they had heard so many store worries and I guess they had a lot of like hamsters, and the hamsters would get stressed out and they'd eat their young, so it was like a stress thing. But you're saying that, like, it definitely happens sometimes, but it's probably not the most common example of cannibalism.

00:22:12
Speaker 10: So, I mean, the most part is like the eating you're on is kind of like a byproduct of just eating your conspecifics, right, So it does happen.

00:22:18
Speaker 3: Sorry, what's a conspecific for those of us who are not biologists.

00:22:21
Speaker 10: Sorry, conspecific means like a member of your own species. I see, Okay, because sometimes cannibalism gets so confused with like predation, but it has to be the same species or.

00:22:31
Speaker 6: It's not cannibalism.

00:22:33
Speaker 10: So in most scenarios where you have cannibalism, you get the accidental or occasional eating of your own offspring, right, and so incentce Like, we did a study in flower beetles, so we kind of tried to figure out whether these guys recognize their eggs their own eggs and whether they would eat them less, because these are really cannibalistic. And so what we figured out is that, yes, they do seem to recognize it, but that just means they eat them some what less, not that don't eat it.

00:23:04
Speaker 6: Right.

00:23:05
Speaker 10: And so I feel like many examples, it's kind of like when the risk of encountering your own like babies is relatively there's no real selection for like recognizing or worrying about it, and you just eat whoever's like it fits in your mouth sort of perspective.

00:23:22
Speaker 6: And sometimes those may be your offspring and sometimes they're not.

00:23:25
Speaker 10: And I think in the case of the hamsters and the others, it's like they would probably eat other babies too. In there, it's not that they specifically want to eat their own babies. They're just like stressed at they're trying to remove competitors the territorial and there's just not enough of a bear to like select against not eating your own in that scenario.

00:23:44
Speaker 3: But yeah, I'm still trying to understand the fact that there's no selection pressure against eating your neighbor's kids. I mean, don't a lot of creatures survive because of communities, You know, A bunch of penguins held together to survive the wind, or a pride of lions help each other out or whatever. Don't we all get along better if we stop eating our kids and worry about our kids being eaten every time we leave the house. Isn't there some benefit to that?

00:24:08
Speaker 10: I just brought up the pride of line because lines are also pretty cannibalistic, so i'llout that helping now. In fact, you often have so like the meals go in and like when the takeover, probably to especially like kill all the offsprings of the female and eat them because they want to be like the dad's of the kids and not like raise somebody else's kid. At least that's how the theory goes. I mean, that's a very sort of group selecting perspective, which is an interesting discussion. I'm sure Kelly has some ideas about it too.

00:24:40
Speaker 3: Is that a controversial topic or something partial because we don't understand whether it happens or some people believe it does and some people who believe it doesn't. Or as a non biologist, I don't know what sort of the third rail to discuss in terms of.

00:24:54
Speaker 10: Evolution, because it's a hard scenario to really make work to like care and like help the unrelated individuals. It's a complicated strategy to get working because it's just so prone to cheating. And so usually when you see this or like helping behavior, that's kind of like more something where it's like your offspring or your siblings or something like that. In that case, is it comes back to like kind selection and inclusive fitness, which is also something that influences cannibalism. In fact, for the helping, I often like to think of this altruistic behavior, and cannibalism is like the flip side of a coin. Right, then both extreme there's the helping and being mutualistic and beneficial, and then there's the other extreme of like just being as selfish as you possibly can. And so cannibalism is like the selfish as possibly can because you're literally killing someone on for your own benefit, right, it's hard to be more selfish and understanding at what point you know, like selection favors one strategy over the other.

00:25:55
Speaker 6: That's kind of like I think one of the interesting questions.

00:25:58
Speaker 1: Yeah, I feel like my take on it is that for a while, you know this idea that animals were doing things for the benefit of the species was kind of a popular idea. It was a long time ago, and then pretty quickly when we started digging in, it just.

00:26:10
Speaker 2: Wasn't making sense.

00:26:11
Speaker 1: And doing things for the benefit of the species at the expense of yourself just sort of doesn't really work evolutionarily. And now the big question is when organisms are helping each other, why the heck are they doing that.

00:26:21
Speaker 2: So we've almost swung to the opposite direction.

00:26:23
Speaker 1: Now we're trying to explain why animals help each other out, and often it turns out that they're related in some way, or maybe they're like reciprocally sharing resources, and it's like, all right, you helped.

00:26:33
Speaker 2: Me out, so I'll help you out.

00:26:34
Speaker 1: But like if someone doesn't help out, then you know, maybe you eat them instead. That's sort of my take on how we've sort of swung from one direction to another.

00:26:42
Speaker 3: Is that how biologists all look at each other. They're like, look, we'll collaborate on this paper, but if you stop pulling your weight, I might just eat you.

00:26:48
Speaker 2: Academia is tough, exactly, but not that tough.

00:26:52
Speaker 3: I guess. Well, you know, something that's forefront in my mind during this conversation is the obvious counter example which is humans right, as humans, we do help each other out. Young men go off and die in wars to protect other people. It's also one of the examples of a species that maybe has less cannibalism than other species. Is it because we've succeeded to help each other out so much and work together as a society. Is that why we have a stigma against cannibalism? Or are you going to tell me that people eat each other just as much as other species.

00:27:22
Speaker 10: So I'm not an althropologist, but it's like when we so I looked into some of this, we kind of got into the anthropology literature, and I will say, like, for most of the human history there's been an element of cannibalism, and they're linked back to Neanderthal it's different cultures. The point at which all societies, as far as we know, stop cannibalism is actually pretty recent, like and some of Papua New Guinea you still have cannibalism, and they're like the nineteen fifties to nineteen seventies somewhere around that. So for modern humans, right, twenty first century humans, that's definitely true. But in the past cannibalism has been pretty much part off like many different cultures, like across all the different continents, and that ranged between you know, like some ancestral ritual. It's about now ensuring that you ants live on to like getting the powers of your enemies and these sort of different commonents. So humans have definitely engaged in cannibalist activities in path societies for sure.

00:28:23
Speaker 1: You mentioned that in the nineteen fifties cannibalism was still happening in Papua New Guinea and that group became fairly famous because of a disease that they got through that practice. And when we come back from the break, we're gonna go ahead and talk about that.

00:28:34
Speaker 3: So everybody finished cooking up your dinner and get ready to hear about it. Kelly, do you have a snack in front of you? Are you ready to talk about cannibalism?

00:28:56
Speaker 2: Somemore, Oh, you know, I always have snacks.

00:28:59
Speaker 1: I've got my cheese and crackers in salami, and I'm just not thinking too hard about it. And you know, as a person who studies parasites, I never think too hard about what are meeting or maybe I.

00:29:08
Speaker 2: Should, but anyway, it would be a good diet strategy.

00:29:11
Speaker 1: We talked about the folks in Papua New Guinea who were engaging in cannibalism up until the nineteen fifties. And another area of research that you focused on is disease and how it maybe makes cannibalism less beneficial. So can you tell us a little bit more about Kuru and then about disease transmission from cannibalism in the non human animals.

00:29:33
Speaker 10: So Van Koura got famous because it's like it's a prime disease that's in some way you can think of it like creterrali arc up disease, another prime disease that's like an alternative disease.

00:29:43
Speaker 6: And it's interesting about it that it.

00:29:45
Speaker 10: Often can take a long time for it to come up, like in a several years.

00:29:50
Speaker 1: Can you tell us real quick what are prion diseases? Because I think a lot of people don't know.

00:29:54
Speaker 6: About this, right, it's a prime disease.

00:29:56
Speaker 10: Is diseases that are called by infectious proteins, which actual proteins the normally in your body, but they're being inspired to change their shape and that shape then.

00:30:07
Speaker 6: Is not as functional, can cause various diseases.

00:30:11
Speaker 8: Right.

00:30:11
Speaker 10: There's like I mentioned critrial yaka disease, which is like a new generative disease. There are several equivalents that we know of, like an animal disease is like make out disease, a few other ones.

00:30:21
Speaker 3: So if prions are proteins, it means they're not alive, right, there's like little bits of stuff. They are little molecular machines. What makes it a disease and not like a poison? Is it because it replicates itself somehow.

00:30:32
Speaker 10: Or it replicates itself in the body Because it's basically so like a dynamic reaction where it's like you can think of one protein that's like changed in the shape, bumping into the normal shape one and like changing it to that shape like with chain reaction.

00:30:46
Speaker 3: That's crazy. Proteins are amazing.

00:30:48
Speaker 10: It was a long controversy to prove that they're actually the cause of a disease because they're like normal parts of your body and there's no like external infectious agent that was initially identified. So they it's a really interesting history about like how long it took them to figure out what prime diseases are and what causes them.

00:31:07
Speaker 1: Yeah, they're crazy, but so as you noted for the folks who were suffering from this neurodegenerative disease. It was really hard to figure out a cause because there was this long delay between the activity and then the onset of symptoms.

00:31:19
Speaker 2: Can you tell us some more about that before I derailed you.

00:31:21
Speaker 10: The idea was that they found these diseases in certain cultural groups and Papua New Guinea, and ultimately it was tracked to some of their like burying rituals, which involved actually so consuming part of the dead ancestor right so like it handsome diseased, and they figured that this was like the main source and how these things were actually being transmitted. And that's kind of like the history of how curu was linked to the cannibalistic practices in humans.

00:31:48
Speaker 3: Wait, so they would bury the ancestors and then eat them or eat them and then bury them or eat them and bury them. I lost track.

00:31:54
Speaker 6: That's a good question. I've hard to remember how.

00:31:56
Speaker 3: Or maybe it's like that Swedish dish where you bury them, you let them rode for six months and you dig them up and eat them.

00:32:01
Speaker 10: No, I think was before I remember the details. I would have to look that up again. Listening about prime diseases too, the extra very stable so sometimes even cooking can kill them, right, which is another sort of thing that mixed firing disease is weird.

00:32:15
Speaker 3: And so the connection to cannibalism is that if this exists in the person you're eating, you eat the thing, now you have the protein in you, and so now you have the disease.

00:32:24
Speaker 6: Yes, So that's how it was like traced back.

00:32:26
Speaker 10: It was tricky, but I mean they used to like in the records of like previous infections or like weird behaviors of people and other sort of stuff and trying to trace it back to like where they came from. But of course it's hard to trace a disease back. That sometimes takes twenty plus us to establish and figure out where's coming from.

00:32:43
Speaker 1: Yeah, so how common is this in non human animals? Not necessarily pryons jumping back and forth during cannibalism, but just like any disease, and what kind of diseases are most commonly transmitted.

00:32:54
Speaker 10: It's an interesting question because the things like in one way, you can just think of like cannibalism being so like a way of acting with members of your own species, which can always increase the risk of infection.

00:33:05
Speaker 6: Right, So if you.

00:33:06
Speaker 10: Consume an individual that's infected just by like getting in contact with infacted individual as a good chance that you pick it up.

00:33:14
Speaker 3: What are you saying you're more likely to get a disease if you eat somebody from your own species, then if you eat somebody not from your species. Is that because you're more likely to be susceptible to the same diseases, it's.

00:33:24
Speaker 6: More likely to go to susceptible to the same diseases.

00:33:26
Speaker 10: In fact, there spends like some theories and experiments like Dave Finnick who was like testing that and so that I was like, are you more likely to get infected by your own species?

00:33:35
Speaker 6: They did that actually in tadpoles.

00:33:37
Speaker 10: Believe it or not, they also cannibalistic, some of them spayed for tadpoles actually, and they found that like when they consumed the conspecific that was infacted, they get more likely to be in facted and if they ate another species, And so they used that as like an idea of selecting against cannibalism. And they did find that they were more likely to discriminate against their own species than any other unless likely to eat them. And so there was the idea that disease could select against cannibalism because there's a higher risk of infection.

00:34:08
Speaker 1: Does it depend on the kind of diseases? So, like, you know, if someone's not sneezing anymore because they're dead, they're probably not going to give me the cold or the flu. If I eat their brains, I might get a pry on disease. So is there certain kinds of diseases you're more likely to get or is it not that easy because it's ecology.

00:34:25
Speaker 10: I think ultimately there is not a lot of research on this specific topic. You might be surprising, but them, I was like there, for instance, I have like an insects and others, Like it's pretty common there. When the individuals become infected, then the jest can lead to another infection. But there's also this scenario where like if it's a disease that for instance, needs to be inhaled to get any respiratory tract or like go a certain route and you eat it and they're just go in your stomach and get digested, They're not going to actually become infected, right, So if you consume the individuals before it's an infectious state, especially then you know, like you could actually remove sick individuals from the population. So it really so depends on how much the infection relies on you actually come in contact with it, or whether it relies on you being.

00:35:15
Speaker 6: Ingested by the individual.

00:35:16
Speaker 10: I think there are no hard facts on it, but I think it comes down to the transmission mode of the disease.

00:35:21
Speaker 3: And in general, most of these diseases are killed by cooking, right, So if you cook the creature, you're most likely going to kill the disease, except for preons, which is why they're so terrifying. Right, Yeah, I guess in the natural world, temples don't usually like grill each other before eating.

00:35:34
Speaker 6: There's not a lot of cooking going on in the natural world.

00:35:39
Speaker 3: But is there zero, like I mean, is there really zero use of fire by any other creature other humans? Excuse my completely naive question.

00:35:47
Speaker 1: I don't think chimpanzees are Bonobo's cook over fire. They've got other ways of trying to remove parasites that folks have postulated, but they're not cooking their meat beforehand.

00:35:59
Speaker 3: And so are there other species where cannibalism seems to be sort of disinclined or suppressed the way it is in modern humans or is it really everywhere in the animal kingdom?

00:36:09
Speaker 6: I would say it's almost everywhere. It's like I always call it ubiquitous.

00:36:12
Speaker 10: I'm not saying everybody is cannibalistic, but a lot of them are.

00:36:16
Speaker 6: And there's of course a gradi end, right.

00:36:19
Speaker 10: It's like some species are highly cannibalistic and some species may not be cannibalistic.

00:36:25
Speaker 6: Yeah, it's a full spectrum, I would say.

00:36:27
Speaker 3: And is there any organization to that spectrum. Is it like the more you're fish, like the more cannibalistic you are, or you know, the larger your number of offspring or something. One of the.

00:36:37
Speaker 6: Patterns, well, Kelly is like list digress.

00:36:39
Speaker 10: So I always thought about it, and it's like I don't think there is a general Somatan land list that I can pull that out. I think part of that is because I don't think cannibalism is sufficiently reported in most organisms.

00:36:52
Speaker 6: Sometimes I remember reading like papers.

00:36:55
Speaker 10: About food webs where it's like, oh, like in this food web, there's like, you know that no cannibalistic link in it, And like I looked at it and like pulled out ten spieces that are known to be cannibalistic.

00:37:05
Speaker 6: There's a strong under reporting.

00:37:06
Speaker 10: That makes it difficult to go out there and say, okay, are the general patterns are like certain taxa or certain functional groups and more cannibalistic than others.

00:37:15
Speaker 6: I don't think we even have the data to test that right now.

00:37:18
Speaker 10: That's why I say, like, I do think like most prosit cannibalistic, But then after that it's very hard to make more generalization about which ones are more likely. I think there's certain like if your species with parental care or certain social structure, it's a lot less likely or even selected against it. So there should be some patterns, but I'm not aware of any analysis it'll look to that.

00:37:42
Speaker 3: And when you say underreported, that makes it sound like it's you know, stigmatized or something people who don't want to talk about it. Is it just that we don't have the data because there isn't enough funding, or because it's difficult to gather for some reason, or.

00:37:53
Speaker 10: I think it's because for like decades people stigmatized it.

00:37:57
Speaker 6: Right So if you think if.

00:37:58
Speaker 10: You go back to like Bibil apples Felt was a famous behavior psycologist, and he was the one that I was talked about like they're good for the species, whereas like, oh, we don't do that, and cannibalism was immediately linked into.

00:38:10
Speaker 6: This where it's kind of like, oh, that's just a freak of nature.

00:38:13
Speaker 10: It only happens, you know, like maroond On and Alan and have nothing else to eat over the airplane crashes in the Arctic or something. Right, I was definitely considered as non normal interactions, and I still think to this day it's like it's lester in other interactions.

00:38:27
Speaker 6: Also, it's a lot more than it was let's.

00:38:29
Speaker 10: Say, like in the nineties or the early two thousands, So I was like, so it's getting a little bit more attention. But because of the stigmatization, there was very little research for law, and I felt every time I publish it on my paper at first to argue and saying, actually, this is everywhere, we just don't talk about it, right, So I was like I had to justify why we've been doing this, and then it's not weird and and just you know, like an unnatural behavior, but it's like pretty common.

00:38:55
Speaker 3: So if I had to summarize your entire academic career in one sentence, would it be fair to say cannibalism is everywhere? And actually it's usually good.

00:39:03
Speaker 2: He does a lot of other stuff too.

00:39:04
Speaker 6: But yes, I think it's.

00:39:08
Speaker 10: Fair to say that it's really a part of the natural ecosystem, and in many ways it can be good.

00:39:12
Speaker 6: Right.

00:39:13
Speaker 10: For instance, cannibalism in predatory species can really stabilize predative predynamics and in fact help natural ecosystem do not cyclis much, right, or it can promote coexistence, so it actually plays an important role in natural ecosystems.

00:39:27
Speaker 6: Test we haven't appreciated.

00:39:29
Speaker 3: I didn't expect we were going to end up being pro cannibalism, but here we are.

00:39:35
Speaker 1: We jumped around, which is totally great. But we were talking about parents eating their kids. I feel like it's much worse for kids to eat their parents because like, how can you not appreciate all the effort your parents have put in there?

00:39:46
Speaker 2: But does that happen? Yes, what could you give us.

00:39:49
Speaker 6: Some exp.

00:39:53
Speaker 10: I mean in those cases, well, as if you think about it's like there's subspecies out there, they are pretty much just reproducing once in their lifetime, right. It's like we often think about like these repeated reprodactive events where during a lifetime you have multiple babies and so on. But for many species it's a one time thing. Right, It's like they put all their eggs in the basket that reproduced and in those instances actually is like there are some species. I'm trying to think of it. I think there's at least like a spider species. As essentially, the idea there is that the parents would die anyway, and it's kind of like parent nourishment position.

00:40:25
Speaker 6: Right, It's like they give their kids.

00:40:27
Speaker 10: More food and in this case it's just their last donation and it's them man.

00:40:32
Speaker 6: Right, it's like all in investment, the ultimate parenting.

00:40:35
Speaker 2: Kids, they're always taking taking.

00:40:39
Speaker 3: All right, Well, I feel like I have to connect the obvious dots here. You're telling us that cannibalism is actually pretty widespread. It even existed in human society for a long time. It's often beneficial, and it's probably a good idea to eat your parents. So would you advise cannibalism? Were you saying, like, hey, you're putting your parents to rest, your options or like cremation, burial or sate. Is that something we should have?

00:41:01
Speaker 2: And I'm really shocked you're going there, Daniel, But.

00:41:04
Speaker 10: Okay, yeah, yeah, I feel like I should be answered that question at all.

00:41:10
Speaker 3: Look, when the aliens come, they're going to ask us this question, and we need to have an answer. You know, you.

00:41:14
Speaker 2: Complete the fifth.

00:41:15
Speaker 10: I always go back to like what Kelly says, like with parasites and all items, like that's just an iffy thing.

00:41:23
Speaker 1: God, yeah, we're not going to think too hard about that. So I'm trained as an ecologist. I love hearing about, you know, ecological systems. And I was going through the like titles of papers that you've published, and I got really excited about the bulgie frogs and so tell us about why salamander cannibalism results in bulgie frogs.

00:41:45
Speaker 10: So the frogs is the tadpoles that are bulgey, right, So now that people think of like giant blobby frogs, so they're actually tadpoles and they like get bulger by getting these like out of jelly layers that really make him.

00:41:57
Speaker 6: Way bigger than they normally would be.

00:42:00
Speaker 10: And so that's a species in Japan and like one of our collaboratives that came across and it's a defense mechanism, but being bigger, they can't get eaten by salamanders potentially because they don't fit in their mouth right, So it's like blow yourself up like the popper fish, so you don't fit in somebody else's mouth.

00:42:17
Speaker 6: Which means you survive too big to fail, and so and.

00:42:21
Speaker 10: So these researchers found is like so cannibalism in these salamandos, which actually cannibalism in salamandes is really common. I've seen one species so far that it's not cannibalistic, but everybody else have worked with all the other species.

00:42:33
Speaker 6: We're all cannibalistic to some extent.

00:42:36
Speaker 2: But they're so cute.

00:42:37
Speaker 6: They are very cute. I agree.

00:42:40
Speaker 10: Salamanos will leave whatever fits in their mouth, right, It's kind of like if it moves, they'll try to shove it in.

00:42:45
Speaker 3: Their mouth like toddlers. I'm convinced if your parents would fit in your mouth.

00:42:53
Speaker 10: They probably would just shove it out there. It's like, if you don't think about it, right, it's just like food, exactly more food and so in salomon is. Sometimes you get so like different courts betweens, Like some parents lay their eggs earlier and then maybe like a few weeks later, another egg laying events, right, and these guys hatch and they're smaller than the earlier ones. And for those early ones they often get eaten by the older salamon the larvae, and because of that, they actually grow a lot faster and get bigger, like way bigger than they would without cannibalism. Right, So there's the clear beneficial roll of like you now eating it con specific to get bigger and stronger, and that's like accelerates growth for a few individuals, as like the cannibolts in the system, and they are the ones that then also pose the biggest risk for the tadpolts in the system because that's the other main food source. And so when you have those giant cannibals in the system, that select for balgy tadpoles. And so that's kind of how to get the feedback.

00:43:58
Speaker 1: So why aren't the tadpoles all is bulgi? Is it just like hard to move around if you're always bulgy, So you only do it if you have to be bulgie.

00:44:06
Speaker 10: I think there's a big investment cost in doing that, and they don't have to they don't do it. So it's kind of like an antipredator response, like once the predation is clearly happening, they're like, oh crap, like I better get boldry fast.

00:44:21
Speaker 3: So it's expensive, but it saves your life. Yes, but you don't do it unless you have to exactly excellent. So this is something at the cutting edge of understanding cannibalism. Can we zoom out and understand like what are the big questions remain? Like you're a researcher, your professor, you're doing research right now in a cannibalism What is like a big question you would love to know the answer to about cannibalism, or what are we going to know about cannibalism in twenty years that we don't know today?

00:44:45
Speaker 6: Thanks, I get for me.

00:44:47
Speaker 10: What's something we're working on and we currently actually have a grant they'd just like submitted to look at this more. It's trying to understand kind of like what limits cannibalism because, like what I've seen work with a bunch of different spieces, there a range of cannibalistic behavior, like I said, that goes from like the super cannibalistic, right, it's like they see another conspasy, they will eat them.

00:45:10
Speaker 6: I merely was one where like it's prutty uncommon.

00:45:13
Speaker 10: Even within the same species, you can find populations where some or more cannibalistic than others, and it has a genetic component to it, so it's not just like some environmental media one. It's like it's an inherited trade, where like some are more cannibalistic, some or less, and we don't really understand why. And I always like to think of this, whereas I said before, catalysm is a form or the ultimate selfish behavior. And kel I mentioned before that for like decades people were really interested in kind of like, Okay, when should selfish behavior move to altruistic behavior? And we spend on like decades on like figuring out when vidualism antalism should happen.

00:45:52
Speaker 6: But we don't really have a rule.

00:45:54
Speaker 10: It tasts like what should stop being extremely selfish?

00:45:58
Speaker 8: Right?

00:45:58
Speaker 10: Why isn't everybody as cannibalistic as they can possibly be?

00:46:02
Speaker 6: Right? There has to be something that's limited.

00:46:05
Speaker 10: And so what we're trying to understand is like, what are the environmental conditions that can do this? Is this something that really can go in different ways? And they are like multiple behaviors that can mitigate the cost of cannibalism. We talked about like one big of the cost of cannibalism is eating your own offspring, right, your own children, because that's a big loss of fitness. You can mitigate this by recognizing your own offspring, and you can still be as cannibalistic as you want, right, because then you's like set off the cost of fitness loss, but you can still remove your competitors.

00:46:38
Speaker 6: You can still get extra meals and all that stuff.

00:46:40
Speaker 3: And your kids competitors. Right, if you eat your neighbor's kids, then your kids are like top of the class.

00:46:44
Speaker 2: Right, So many lessons here.

00:46:49
Speaker 10: So there are many different ways of like mitigating the cost of cannibalism. And it's more like so like a behavioral multidimensional space where you can like just recognize them, or could be that your kids just get the genes to get the hell out of here, right, leave your parents as fast as possible and walk.

00:47:05
Speaker 6: Away from them.

00:47:06
Speaker 10: And then also like the parents can just continue to be cannibalistic. Right, So the different behaviors that can play a role with it, and understanding how they're all interact with the jail that to really drive the evolution of cannibalism, and then see how that can like explain a lot of the variation that we see within and across PCs.

00:47:24
Speaker 6: I think that's a big question for us.

00:47:26
Speaker 1: So you said, you've been like beating the drum that like cannibalism is common, this happens all the time. We need to understand it more. Has that message gotten out? Are ecologists over the stigma? Are more people studying this now?

00:47:35
Speaker 10: I think there are more people studying it now. It's like I'm not sure that this is because of me or whether that's just well, actually, I'm pretty sure it's not because of me.

00:47:43
Speaker 6: I'm sure there's nothing to do with it.

00:47:45
Speaker 10: I think that the stigma is like seeded in is just by having more and more studies over the time to like look at this. I know that there's been like a popular book on cannibalism that came out a few years ago that it was just on like talking about the misconception behind and how that's pretty common. I don't think it was actually a scientist necessarily who works on it that wrote it, but they just thought it was a cool topic or something that probably helped too to like get it more out and then like public's mind.

00:48:10
Speaker 6: But I think for researchers it's funny.

00:48:12
Speaker 10: Whenever I gave this talk and then talked about cannibalisms and other things, and people would.

00:48:16
Speaker 6: Always come up and say, yeah, I see this all the time and just never thought about it, or like what are the consequences?

00:48:21
Speaker 10: And so right post people that work in natural system, unless they're work on plans, probably have seen cannibalism at some point, Like you said, like or at home, I do you see you fish getting eatings and you're like, oh, how Colm, I'll never get you know, more guppies.

00:48:34
Speaker 6: And it's like they're eating ill got eaten up. Yeah.

00:48:39
Speaker 1: One books that cannibalism have the best titles I've got is Eating People Wrong, which I found on my husband's table the other day and I got fairly nervous. So the children and I you know, went on a vacation. But it turned out it was not about us, just for research, just for research.

00:48:56
Speaker 3: Well, what about portrayals in popular media? You know when I watch a show and they talk about particle physics and often cringing because they get all the details wrong. If you watch Silence of the Lambs or you know that TV show Hannibal was very popular, are you cringing because you're like, oh my god, that would never happen that way, or are you just glad to hear people talking about cannibalism since it's your position that more people should do it.

00:49:21
Speaker 10: They both of this is nolla, right because like all the human cannibalism is nothing that I do.

00:49:26
Speaker 6: It's all really like a psychological, mostly weird behavior that it's.

00:49:32
Speaker 10: Not in line with like the natural cannaalistic behavior that we see like in these ecosystems. So no, it's like, I don't think they get it wrong because to me, it has nothing to do with what I see out in nature.

00:49:44
Speaker 1: All right, So Folka is not saying that any of us should engage in cannibalism. No, And I think that's where we need to end this conversation.

00:49:54
Speaker 10: I feel like we pushed you to like brace it and adorse it, but like, no, we should study it more, not actually do it.

00:50:02
Speaker 3: That's right, right, all right, the lawyers have gotten to you both. You're so afraid to say the truth, all.

00:50:08
Speaker 2: Right, all right, Well, thank you so much for being on the show.

00:50:12
Speaker 1: You might have noticed I've avoided saying your name the whole time because now I'm convinced that I'm doing it wrong and I'm super.

00:50:18
Speaker 2: Embarrassed about it.

00:50:19
Speaker 1: But anyway, this has been a ton of fun. Thanks for being a good sport about all of the jokes that we made and the weird human references that we insisted on shoehorning in. And we look forward to having you back on the show in like a decade to tell us about what you've discovered.

00:50:32
Speaker 6: All right, it sounds good.

00:50:33
Speaker 3: Thanks for having me, Thanks for the delicious conversations.

00:50:44
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