Pod Insights Daniel and Kelly's Extraordinary Universe The curious lives of social amoeba About this episode Daniel and Kelly talks about a species of social amoeba that will die to help others. Why the heck does it do that? And bonus: the amoeba are farmers!
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Transcript 12,521 words · 7 speakers
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2:14 Kelly Weinersmith? You've heard us say many times that we're kind of amazed that our complicated bodies ever work well. There are countless cells that are born in your body and will die in your body. And from an evolutionary perspective, all of those cells are working their tails off to help a particular group of cells kickstart the next generation. And even then, just a few, if any, sperm or eggs will get a chance to come together to make a baby. But you don't hear about eggs creating a roadblock in the fallopian tubes as they all race out in a mad rush to be the egg that gets picked that month. Many of our cells do coordinate nicely to give sperm and eggs a chance to strut their stuff. But all of those cells are carrying around the same genetic information, so they all benefit from the sperm and the
2:59 Kelly Weinersmith? egg knocking it out of the park when their time comes. But what happens when cells need to come together to complete a selfless task and those cells are not 100% related to each other? Today, we're going to talk about social amoeba, who will sometimes join together by the tens of thousands to help a subset of the amoeba get to a new and better environment. In the process, about 20% of the amoeba need to give their lives so the rest of the amoeba can get transported to somewhere, hopefully, much better. So how the heck do you convince someone who isn't related to you to give their life for you? And how do you prevent cheaters from avoiding their fair share of the cost? Welcome to Daniel and Kelly's Occasionally Cooperative Universe.
3:57 Daniel Whiteson? Hi, I'm Daniel. I'm a particle physicist who likes thinking about aliens, and I also like cooperating with humans.
4:04 Kelly Weinersmith? Hello, I'm Kelly Wiener-Smith. I study parasites and space, and I also like cooperating with humans.
4:10 Daniel Whiteson? And I cooperate with microbes all the time. Like I had dinner last night and right now we're working together on digesting that.
4:17 Kelly Weinersmith? Oh, you're collaborating on a poo?
4:21 Kelly Weinersmith? Is that what you're getting at?
4:24 Daniel Whiteson? I wasn't going to go there, but you brought us all the way from zero to poo in record time. Thank you very much. And welcome everybody to a biology episode. Because we're talking about poo.
4:34 Kelly Weinersmith? I think we might get to cannibalism too. So pull out your D K E U bingo cards. We'll see where we get today.
4:39 Daniel Whiteson? But yes, I'm happily a commensable organism. Commensurate.
4:44 Kelly Weinersmith? Commensal?
4:45 Daniel Whiteson? Commensal. Thank you very much. With the microbes in my gut. And we're both working on my dinner from last night. That's the way I like to think about it.
4:53 Kelly Weinersmith? Okay. Yeah, that's a nicer way to think about it. But Daniel, I have a story for you. So you might be amazed to learn that I was ever not good at interviewing people.
5:06 Kelly Weinersmith? So the social amoeba that we're talking about today, used to be called slime molds. And I don't know if you remember, but for a while there, Zach and I were working on trying to manufacture mazes for slime molds that could be given to like schools as kids to study slime molds. And so I was like, Oh, I'm going to interview a slime mold expert so that I can, you know, learn about this stuff. But she doesn't study that kind of slime mold. It's totally different. And so right when the interview starts, I'm like, well, tell me about, then I say the name of the slime mold that I thought we were going to tell them. And she goes, Oh, no, I don't study that. I study. And it was a totally different thing. And I was like, what? All of my preparation. Clearly, I didn't prepare enough, right? And so now when you're
5:49 Kelly Weinersmith? like, Kelly, why does it take you 15 to prepare an episode? It's because this is living rent free in my brain. And I never want to repeat that again.
5:58 Daniel Whiteson? I see. Everybody's got that potential moment of terror when they're going to be unmasked as totally ignorant on the thing they're supposed to know something about.
6:07 Kelly Weinersmith? And it happened. It happened to me.
6:09 Daniel Whiteson? At least it didn't happen live on the BBC like it did for Naomi Wolf.
6:13 Kelly Weinersmith? Oh, my gosh. When I think about that, I cringe. All right. Tell the listeners what happened for anyone who happens to not be aware of this.
6:19 Daniel Whiteson? Naomi Wolf wrote a book about, let me just make sure I get this right now. I want to have a Naomi Wolf moment about Naomi Wolf.
6:28 Kelly Weinersmith? That was a bad moment to take a sip of water.
6:31 Daniel Whiteson? So Naomi Wolf wrote a whole book about people who she thought were executed in the 19th century for being homosexuals. And she based this on legal records where these cases were indicated with the term "death recorded," which she interpreted to mean that these men were executed, but live on the BBC, being interviewed by a historian who revealed to her that the term "death recorded" actually means that the judges had abstained from handing out a death sentence. She discovered this like as she's being asked about her book in real time. And to me, that's like the most terrifying possible experience. And the book was pulled and it was pulped and like years of research on a foundational
7:14 Daniel Whiteson? mistake. So every time I'm doing research, I'm imagining a potential Naomi Wolf moment. And I'm like, let me just go read that paper one more time. Let me just double check that because nobody wants that to happen to them.
7:25 Kelly Weinersmith? My stomach hurts just thinking about that story. And yeah, to, to, and to find out about it live on the BBC. Okay.
7:32 Daniel Whiteson? Anyway, back to social amoeba, which we were talking about in today's episode. What brought us to this topic today, Kelly?
7:39 Kelly Weinersmith? Well, we have an amazing Discord community that you can join by going to our website, danielandkelly.org. And one of our amazing Discord members, C. Dave, asked about these organisms that when there's not enough food, join together and cooperate, but a subset of them die on the way. And I realized that what he was talking about was dictio stellum discoidum, or just dicties. We're going to call it dictie for the rest of the time. And I happen to know the lab that does that work. And I was like, you know, I would love to actually do the research I should have done 15 years ago, when, when I had Joan Strausman on the show. And so we're going to be talking about the Strausman and Queller
8:20 Kelly Weinersmith? Lab research. It's a husband, wife team that has been studying these amazing social amoeba that are an incredible model for social evolution.
8:28 Daniel Whiteson? All right. So this is not just a fun, deep dive into fascinating puzzles in science. It's also a redemption arc for Kelly to finally get to talk about this topic.
8:39 Kelly Weinersmith? Maybe. I don't know. We'll see if it's a redemption arc or a failure arc by the end of the show. But, but so this, this question was inspired by a prior episode we did where we talked about why animals cooperate, which is a bit of a surprising question because you imagine, you know, nature, red and tooth and claw. Everybody should be about trying to like, get the best outcomes for themselves. And that involves probably not a lot of cooperation. But yet, when we look out in nature, we see loads of animals cooperating with one another and doing nice things like in honeybees, if a worker bee stings to try to protect the rest of the hive, she's disemboweled and she like dies to protect the hive. Why would an animal do that? And in that case, the answer is probably because she's very closely
9:23 Kelly Weinersmith? related to everybody. And so evolution favors her being willing to risk her life if it saves essentially her genes that are living in the rest of the colony mates.
9:33 Daniel Whiteson? And so for those of us who are not biologists, I guess the mystery is based on a sort of simple reading of evolution that like every critter is out there for themselves, trying to pass along their genes. And so how could evolution ever produce a system where somebody intentionally kills themselves for the benefit of other organisms and those organisms genes? And I think you're saying that the answer is that that happens when your genes are very close to the genes of the organism you're sacrificing yourself for. So it's actually still benefiting your genes. Is that right?
10:06 Kelly Weinersmith? Yes, exactly. Right. So almost every single example we find of altruism in nature can end up being explained by a benefit to the individual who is doing what appears to be an altruistic act. And so in the example we just talked about, the benefit is that their genes are also found in their family members and their family members are going to do much better and carry those genes on because of how that individual helped out.
10:30 Daniel Whiteson? That doesn't give me like a nature is warm and fuzzy, though. It's not like, hey, we all care about each other. It's like, you don't even matter. All that matters is your genes. And if your genes exist in your brothers and sisters, you should just kill yourself to benefit them.
10:43 Kelly Weinersmith? Nature does not care about your feelings, Daniel. It doesn't care about anyone's feelings.
10:48 Daniel Whiteson? So it's still pretty red in tooth and claw.
10:50 Kelly Weinersmith? Yeah.
10:50 Daniel Whiteson? And like self sacrifices.
10:52 Kelly Weinersmith? Yes, absolutely. Nature is not nice, says the parasitologist. And I think my favorite quote that helps you sort of wrap your head around kin selection is by JBS Haldane, who, when asked if he would save a drowning brother if it put his own life at risk, said, no, but I would save two brothers or eight cousins.
11:12 Daniel Whiteson? Sounds like a charming fellow.
11:14 Kelly Weinersmith? Yes, yeah, well, the point that he was trying to make there is that he and his brother share about 50% of their genes. So in order to like, replace his loss, you'd have to have two brothers so that you're like, you know, saving enough genes to make it worth it. And, you know, the, the amount that you should be willing to risk as family members become more distantly related goes down over time.
11:35 Daniel Whiteson? Hmm, I see. Sounds like a really cozy Thanksgiving dinner at the Haldane house.
11:40 Kelly Weinersmith? Well, you know.
11:42 Daniel Whiteson? Don't pass the gravy down that end. Those are just cousins. Let's keep it over here on the brother end.
11:46 Kelly Weinersmith? That's right. That's right. I mean, there's got to be some families like that. There have been some rough Christmases out there, I'm sure. I'm sure, in fact, I'm sure some of their listeners are shaking their heads and being like, oh, yeah, I'm in one of those families. So when you're doing these sorts of calculations, it's important to keep in mind what the benefits are going to be and what the costs are going to be. Because if you're going to risk your own life, you want to make sure that there's a pretty big benefit for your family members, for example. Or maybe you're willing to do something nice if the cost to you is low. And then you're like, oh, why not? Yeah, I can help out. I can listen to you tell me about your boring dream. It makes you feel better.
12:24 Daniel Whiteson? And we're couching this in understandable terms from the point of view of the organism, like it's making a decision, should I kill myself? Should I jump in the pool to save my brother? But really, that's not what's happening, right? And this is sort of a meta process via evolution that's selecting organisms who have made choices that propagate their genes.
12:43 Kelly Weinersmith? Yes, that's a great question. And since we're talking about amoeba today, it's going to be very easy for For us to like wrap our heads around the fact that they are not making decisions about like, oh, that's Francine, who I have an emotional connection to, you know? It's just like, that's an amoeba that's like me.
12:59 Daniel Whiteson? Oh, interesting.
13:01 Kelly Weinersmith? Yeah. So should we talk about the puzzle?
13:03 Daniel Whiteson? Yes. Tell us about the puzzle.
13:05 Kelly Weinersmith? Okay. So here's the puzzle. There are these social amoeba called, we're going to call them dicty. And so these are like free living, they're like one cell. They divide asexually a lot of the time. So they just kind of like split and then there's two of them. What? And they eat bacteria.
13:22 Daniel Whiteson? But back up and remind us, what exactly is an amoeba? Because they're not viruses, they're not bacteria, but they're sort of on the same end of the size spectrum as those micro critters.
13:32 Kelly Weinersmith? Yeah, they're, they're small, but they're eukaryotes.
13:35 Daniel Whiteson? Okay.
13:36 Kelly Weinersmith? And so they've got like a nucleus and organelles that are, what is?
13:39 Daniel Whiteson? Organitos.
13:40 Kelly Weinersmith? Organites, that's right, organitos. And they're sort of like amorphously shaped, right? And so if they come across something that they want to eat, they can sort of like move their body around it to engulf it. And so do you think it's fair to assume that most people like have a mental image for an amoeba? Or is that just like a bias of this biologist's brain of mind?
13:59 Daniel Whiteson? I don't think I've thought about amoebas since ninth grade.
14:02 Kelly Weinersmith? Oh, okay.
14:03 Daniel Whiteson? So I'm imagining they're like a mini version of the blob.
14:07 Kelly Weinersmith? Yeah. So like, imagine if you dropped an egg on the ground and then you heated it and it's kind, it has a shape sort of like that, but it's also able to move.
14:16 Daniel Whiteson? Well, I hope nobody ever describes me that way. Not a, not a flattering description.
14:22 Kelly Weinersmith? Your shape is way more defined than that. And so I think you're safe.
14:25 Daniel Whiteson? Well, what would you have to drop on the ground? So it makes a Daniel shaped splat is really the question.
14:31 Kelly Weinersmith? A Daniel, you'd have to drop a Daniel. And then hopefully you're not putting a chalk line around it.
14:37 Daniel Whiteson? I'm not going to make, no, this flat, when you drop Daniel off of a building, it's not going to be Daniel shaped. It's going to be a Daniel splat shaped.
14:43 Kelly Weinersmith? Like Daniel mixed with an amoeba.
14:46 Daniel Whiteson? All right. We're way out of track here. Anyway, you're saying amoebas are sort of large and amorphous.
14:51 Kelly Weinersmith? Not large.
14:52 Daniel Whiteson? Oh, they're not large. They're tiny and amorphous.
14:55 Kelly Weinersmith? Tiny and amorphous. The egg thing was meant to make you just sort of like visualize the shape, but they're nowhere near as big as an egg. These are, they are very teeny tiny.
15:04 Daniel Whiteson? Well, that's a great name. Actually, the word amoeba actually gives me that mental image of like a tiny little blob.
15:09 Kelly Weinersmith? Hmm.
15:10 Daniel Whiteson? There's something blobby about it.
15:11 Kelly Weinersmith? Is that because like you know that it's a tiny little blob?
15:14 Daniel Whiteson? Yes, maybe I do. I don't know.
15:16 Kelly Weinersmith? All right.
15:16 Daniel Whiteson? All right. So amoebas are tiny little blobs and they slide around absorbing stuff into them. But they're not bacteria, but they're roughly the same size.
15:24 Kelly Weinersmith? They're bigger than bacteria. They are actually predators of bacteria. You could see them under a compound microscope. They are usually less than a millimeter long.
15:33 Daniel Whiteson? Okay, so we have these little critters. They're less than a millimeter long. And tell us about the puzzle.
15:38 Kelly Weinersmith? Okay, so here's the puzzle. So they're going around, they're eating bacteria, doing their amoeba thing. And then the environment changes. Maybe you've been living on a turd and all of the good bacteria have been consumed and now the environment is becoming less good. And you need to figure out some way to high tail off that turd to get to the next one. And so what they do is they start releasing chemicals to aggregate so that they can find each other. And they start pulling together in groups of 10,000 to 100,000 individuals.
16:09 Daniel Whiteson? What?
16:09 Kelly Weinersmith? Right.
16:10 Daniel Whiteson? How can there be so many of them?
16:11 Kelly Weinersmith? I mean, they're really tiny and there used to be a lot of food in that turd buffet, but now, now there's not. And so now they need to move to the next buffet.
16:20 Daniel Whiteson? Okay.
16:20 Kelly Weinersmith? And so they join together in what is called a slug.
16:24 Daniel Whiteson? Oh.
16:24 Kelly Weinersmith? And it looks like a slug, like, and so there are so many of them joined together that now you can see the trails when they move together.
16:30 Daniel Whiteson? Wow.
16:30 Kelly Weinersmith? And these groups can move something like two and a half centimeters on average together, which is a pretty big distance for like,
16:38 Daniel Whiteson? Yes.
16:38 Kelly Weinersmith? Yeah, a tiny little critter.
16:40 Daniel Whiteson? A millimeter. Wow.
16:41 Kelly Weinersmith? That's right. And so then when it gets to its final location, some of it lifts up into the air and forms a ball on the top. And so now it starts looking like a lollipop. And the bit of the lollipop that's in the stick, those are all amoeba that are in there. 20% of the lollipop is the stick and they die. They die so that they can form a hard stalk so that the stuff on the top can then transmit to other places.
17:08 Daniel Whiteson? Remind me how many amoeba are in this slug again, roughly?
17:11 Kelly Weinersmith? 10,000 to 100,000.
17:13 Daniel Whiteson? Wow. And so they all work together to make this like fake macroscopic organism that can move. Much further away than an individual one could.
17:23 Kelly Weinersmith? Yep.
17:23 Daniel Whiteson? But along the way, a bunch of them have to die. So this is like, if I got a bunch of students here, you see, are lined together, like 10,000 of them to form some huge blob of students and they managed to like lift some of them to safety in some disaster. But some of them died along the way.
17:39 Kelly Weinersmith? Yeah.
17:40 Daniel Whiteson? That's crazy.
17:41 Kelly Weinersmith? Exactly. It's nuts. And also, nobody should work with Daniel because he's, this is just scary.
17:47 Daniel Whiteson? I'm just trying to make it relatable here.
17:49 Kelly Weinersmith? Okay, all right.
17:50 Daniel Whiteson? All right.
17:50 Kelly Weinersmith? It's very real. It's visceral. It's visceral now. And so, yeah, 20% of them will die and harden to create like a lollipop stick. So that up at the top, the rest of the amoeba can transmit. And part of how they transmit is like a fruit fly or some other kind of fly might, you know, land on the turd, walk past it and then pick some of the, they're, they're called spores at this stage. But let's just call the, we'll pick some of the amoeba up and then bring them to somewhere else.
18:17 Daniel Whiteson? Okay.
18:18 Kelly Weinersmith? Or like the lollipop head will eventually like dry out and kind of like disperse in like the wind. And so the amoebas can, by getting up high, either hitcher ride on other insects or like get sort of blown somewhere else. And so in that way, they're hoping that they end up in a better environment.
18:34 Daniel Whiteson? And how do they decide who ends up in the head and who ends up in the stick? Is there like a big battle for that?
18:40 Kelly Weinersmith? That is like 20 years of research and that is what we're going to talk about today.
18:45 Daniel Whiteson? Okay.
18:45 Kelly Weinersmith? And so when we get back, we will start to discuss who ends up in the stalk and who gets to survive in the head.
18:52 Daniel Whiteson? Who wins the amoeba hunger games?
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22:37 Kelly Weinersmith? And we're back. And today we are discussing who lives and who dies in the amoeba hunger games.
22:45 Daniel Whiteson? I'm also wondering how to describe what it is that amoebas do. You said earlier amoebas doing the thing amoebas are doing. It feels like that needs a word like amoebing.
22:56 Daniel Whiteson? What is the word for that? What do amoebas do?
22:59 Kelly Weinersmith? Amoebing sounds good. Amoeboiding or something. And what would be the human equivalent? Like, would that be like when I wrap my face around a popsicle or something? I don't, I don't know.
23:11 Daniel Whiteson? Humaning, yeah, that's sure.
23:13 Kelly Weinersmith? Yeah.
23:13 Daniel Whiteson? All right, so amoebas be amoebing. And while they're amoebing, some of them sacrifice themselves so that the rest of them can amoebi longer into the future.
23:24 Kelly Weinersmith? That's right.
23:24 Daniel Whiteson? How do they decide who's in the stock? And who gets to be the special baby at the very top?
23:30 Kelly Weinersmith? OK, well, so the first part of the answer is that the weak do not survive. And so there was an experiment where they took clones. So all of the amoebas were very closely related. They were like, you know, completely related to each other because they just split many, many times to make more clones. And some of the clones were put on a plate without a lot of bacteria. And so they were weak and kind of starving. And some of the clones had a lot of food. And then when you put them all back together and you look to see which ones end up in the stalk and which ones end up in the head, the ones that were starving are the ones that end up in the stalk.
24:05 Daniel Whiteson? Oh, I see. And so the reason you use clones in this experiment is to make sure that there's no genetic differentiation. You're focusing just on the weak versus the strong guys?
24:15 Kelly Weinersmith? Exactly. Yes.
24:16 Daniel Whiteson? All right.
24:16 Kelly Weinersmith? Honing in on the clones is important and we're going to get to that. But another way that you end up in the head instead of in the stalk is by being one of the first individuals to say, hey, there's not a lot of food here. We need to do the slug thing, which is surprising because I'd feel like you should have expected the opposite, like whoever starts saying, oh, I'm hungry. We need to start the slug. You'd be like, okay, but you've got to be one of the ones who dies. Because otherwise, why would anybody join? Like, yeah, okay, I'll help you out. There's like, you know, a 20% chance I'm going to kick the bucket if I help you out, but I'm going to give you a hand. So that's kind of surprising to me.
24:53 Daniel Whiteson? But that also makes me wonder, how does this begin? Is it one amoeba decides like, hey, guys, it's stalk time? Or is it a collective decision? Or how does that happen?
25:02 Kelly Weinersmith? For the creation of the slug, we don't know exactly because watching this kind of stuff in nature is pretty hard. But I think that it is like some individuals who are maybe in the part of the plate where most of the bacteria have been eaten are the first to start getting hungry. They start releasing some chemicals into the environment. And so I guess the other amoebas could be like, oh, this is a clue that this environment is about to be going downhill. And so I'm going to go ahead and join you. Or maybe they also have a sense, but they're just lagging a little bit further behind. Maybe they also have a sense that the bacteria, food and the environment is starting to go down. So then they start releasing chemicals and everybody who has quote unquote, decided to join the slug starts releasing chemicals and that creates these really big aggregations.
25:41 Daniel Whiteson? Hmm, interesting. And so when there's like enough of this chemical in the environment, it changes all of their behavior.
25:47 Kelly Weinersmith? Yeah, yes.
25:48 Daniel Whiteson? You know what I wish we had that for? I wish we had that for Zoom meetings. Like if enough people on a Zoom meeting want it to be over, it should just like automatically end.
25:57 Kelly Weinersmith? Amen. Yes. The screen should just go dark and you should be like, yes. And that way, no one has to declare their preference. It just, you can start secreting things onto your screen.
26:08 Daniel Whiteson? Exactly. That would be lovely.
26:10 Kelly Weinersmith? That would.
26:11 Daniel Whiteson? Let's slug this meeting. Anyway, all right. But part of the mystery is that the folks in the bacteria poor, the food poor region, aren't the ones who end up sacrificing themselves. They're the ones who end up being safe. So they're like calling for assistance and the people who come to help them end up losing out.
26:27 Kelly Weinersmith? Often they end up losing out. Yeah, that's sort of the counterintuitive thing. And so at this moment, I think we want to start talking about the costs and benefits here. And so one of the benefits of being in a group is that the bigger the slug is, the farther it travels.
26:44 Daniel Whiteson? Makes sense.
26:44 Kelly Weinersmith? But also, if the slug is made up of all the same clone, like in the lab, if you just let the amoeba divide like crazy and then they all join and make their own slug.
26:55 Daniel Whiteson? Yeah.
26:55 Kelly Weinersmith? Slugs that are the same size, if you compare the clone slugs to what they call a chimera slug, a slug that's got a couple of different clones, the clone slug goes farther.
27:06 Daniel Whiteson? Interesting.
27:06 Kelly Weinersmith? So they work together more nicely when they've got like family around. But in the end, we think the benefit of working with other amoeba is that if you can get your slug like twice as big.
27:20 Daniel Whiteson? Yeah.
27:21 Kelly Weinersmith? Then you're going to go even farther than you would have gone with half as many of your clones.
27:26 Daniel Whiteson? Yeah. And in the bigger slugs, do the same proportions survive? Is it like still 20% end up in the stalk? Or does that change as they get bigger?
27:36 Kelly Weinersmith? Yeah, it's always about 20%.
27:38 Daniel Whiteson? Okay, so increasing the slug doesn't change your odds of surviving, but it does mean that the slug might get further.
27:45 Kelly Weinersmith? That's right. Okay, so now you've got these slugs that can either form with all clones or they can be chimeras, multiple different clones together.
27:55 Daniel Whiteson? Yeah.
27:55 Kelly Weinersmith? And so you would expect that if you've got a situation where multiple clones are in the same slug.
28:03 Daniel Whiteson? Yeah.
28:04 Kelly Weinersmith? There should be pressure to cheat, right?
28:05 Daniel Whiteson? Right.
28:06 Kelly Weinersmith? Pressure to like try to run into the head and get, you know, the loser clone to be in the stalk.
28:11 Daniel Whiteson? To get them down at the like the dark meat side of the Thanksgiving table.
28:14 Kelly Weinersmith? That's, oh my gosh, I also hate dark meat. Oh, Daniel. Dark meat, bad. White chocolate, bad. Dark chocolate, good. White meat, good. I'm so glad you and I agree. And also, the listeners should know that you and I are wearing very similar colored shirts today. We both have our black glasses on. It's a good twinsy day for DK here. All right, so moving on. So you would expect there to be cheating. And in fact, you actually find a linear dominance hierarchy. So this lab went out in the wild and they collected a bunch of different clones from a city called Little Butts Gap, which I love so much that I had to include it.
28:55 Daniel Whiteson? I mean, that's the kind of place you expect to find amoeba, right?
28:57 Kelly Weinersmith? That's right. That's right. Well, they live on poop and so you go to Little Butts Gap. And so, anyway, so at Little Butts Gap, if you get a bunch of different clones of amoeba, and then you put them together in a bunch of different pairwise situations, what you find is that there are some clones that are just better than other clones at getting into the top and avoiding paying the cost.
29:22 Daniel Whiteson? Okay.
29:22 Kelly Weinersmith? And when I say that it's linear, I mean, it's like you can rank them in order of how good they are at avoiding being in the stock. And so like you can rank them from one to 10, and clone number one is always going to be better than clone two, three, four, five, six, seven, eight, nine, and 10 at getting into the head. And clone two isn't as good as clone one, but it can beat clone three, four, five, six, seven, eight, nine, 10. Does that make sense?
29:45 Daniel Whiteson? Yeah. All right. So we've got a lot going on here. We said that slugs that only have one species, them one genetic imprint, do the best. When you mix the species together, you have this chimera slug, it can still do well, but not as well. And then within the chimera, there are some genetic variants that end up in the good part more often and in the stock part less often.
30:08 Kelly Weinersmith? That's right.
30:08 Daniel Whiteson? And you can rank those. So basically, like, some relatives are better at getting to the white meat end of the table, and those guys from Little Butts Gap who showed up late always end up with the dark meat side of the table.
30:19 Kelly Weinersmith? That's right. And they don't play nice. They don't like decide, oh, I'm going to share to make it even. But, but again, one thing that you need to remember is that that comparison you made between Slugs of all one clone or chimeras.
30:30 Daniel Whiteson? Yeah.
30:31 Kelly Weinersmith? The clone moves better when those slugs are the same size.
30:34 Daniel Whiteson? Oh, I see.
30:35 Kelly Weinersmith? But if you can signal, hey, I need help and the slug ends up being five times bigger because you got a bunch of different clones there.
30:42 Daniel Whiteson? Right.
30:42 Kelly Weinersmith? Then it's going to go even farther than you would have gone alone.
30:45 Daniel Whiteson? All right. So it's better to include other species because it's going to make your slug bigger and you're going to go further. If you don't have any more of your own friends around.
30:54 Kelly Weinersmith? Maybe, but now there are these trade offs to contend with because depending on who you're interacting with, they are going to differ in how much they're cheating.
31:02 Daniel Whiteson? Oh.
31:03 Kelly Weinersmith? Cheating is what we call it.
31:04 Daniel Whiteson? So for example, if you end up attracting a bunch of folks who are really good at getting to the tip, you're going to be worse off yourself. You're going to end up somewhere near the middle of the table.
31:13 Kelly Weinersmith? Exactly. Right. So what you want to do is you want to try to find other cooperators.
31:19 Daniel Whiteson? Yeah.
31:19 Kelly Weinersmith? And so you might remember that in the last episode where we talked about cooperation, you were like, well, can sort of quote unquote, lower organisms actually even recognize family members or can they in some way recognize another cooperator?
31:33 Daniel Whiteson? Oh, I asked that last time. I was about to ask that this time. Like, how do they even know?
31:36 Kelly Weinersmith? It's, yeah. So it's a great question. And so there's this idea that Richard Dawkins named the green beard effect.
31:44 Daniel Whiteson? Okay.
31:44 Kelly Weinersmith? And so the idea here is that if you want to selectively work with other cooperators.
31:50 Daniel Whiteson? Yeah.
31:50 Kelly Weinersmith? What you need is at least one gene that has three different criteria. The gene needs to create something that can be seen by other individuals, like a green beard.
32:02 Daniel Whiteson? Yeah.
32:03 Kelly Weinersmith? Other individuals need to be able to like actually recognize that trait.
32:06 Daniel Whiteson? Okay.
32:07 Kelly Weinersmith? And then you need to be able to preferentially work with the individuals that have that trait.
32:13 Daniel Whiteson? So it's like a uniform, right? You're on the battlefield. Everybody's got a uniform to indicate which side they're on. You can recognize the uniforms and also you know how to work together.
32:22 Kelly Weinersmith? Yes.
32:23 Daniel Whiteson? Okay. Makes sense.
32:24 Kelly Weinersmith? Yeah, exactly. Okay. And so the Strassmann Queller lab thought that they found a green beard gene. And so what this gene did was it essentially produces a molecule on the outside of the amoeba that helps it stick to other amoeba. So it would be like, it's like it's. Reaching out its hands to grab another amoeba.
32:41 Daniel Whiteson? Okay.
32:41 Kelly Weinersmith? And this is important because if you are not holding on to the individuals that are nearby, you have a tendency to slide towards the back of the slug. And the back of the slug is where the head ends up being made.
32:54 Daniel Whiteson? Oh.
32:54 Kelly Weinersmith? And so you want to find individuals who are going to reach out and hold your hand, because that's a way of saying, I am not going to try to sneak to the good part of the slug. I'm gonna stay with you and whatever my fate holds, I will be here to see it. You know, it's a way of indicating you're an altruist.
33:12 Daniel Whiteson? Yeah, you're a cooperator.
33:13 Kelly Weinersmith? That's right, you're a cooperator. And so if you knock this gene out, but you still find some way to like make the slugs form in the lab, you will find that these individuals tend to like slide towards the back.
33:24 Daniel Whiteson? Hmm, and the back is the good direction.
33:27 Kelly Weinersmith? The back is the good direction. That's where the head's gonna be.
33:30 Daniel Whiteson? That makes no sense at all. The back is where the head's gonna be.
33:33 Kelly Weinersmith? Yeah, well, you know, nature doesn't, nature doesn't care if it's intuitive or not. And so they're arguing that this gene is essentially a way to find other individuals who are willing to be altruistic. So if you can reach out and grab the hand of the amoeba next to you and hold on to it, you can say, all right, you are here with me, no matter what our fate ends up being. And so you can try to preferentially bind to these individuals that have this protein that can bind the amoeba together.
33:58 Daniel Whiteson? So I get that they can have this protein and they can bind them together and help them cooperate. And if you were an amoeba, you would want to find other ones that can cooperate. The bit I missed, and maybe you said this, is how does that get them closer to the back?
34:13 Kelly Weinersmith? So if you don't have this gene.
34:16 Daniel Whiteson? Yeah.
34:16 Kelly Weinersmith? Then you aren't sticking your hands out.
34:19 Daniel Whiteson? Right.
34:19 Kelly Weinersmith? And so if you can manage to get yourself into a slug, then you can slide towards the back because you're not holding anyone's hand. So you can just sort of like tiptoe to the back of the slug and manage to get yourself in the head position. And so by preferentially working with amoeba that are putting out their hand, then you can make sure that your slug is mostly other individuals who are willing to play nice.
34:42 Daniel Whiteson? I see, so it's not that by holding hands, you get to the back more often, but by choosing other People who will hold hands, you're choosing against folks that are going to cheat, sneak around you and get to the front of the line for the white meat.
34:55 Kelly Weinersmith? Yes, exactly.
34:56 Daniel Whiteson? Got it.
34:56 Kelly Weinersmith? Right. Okay. So that's one way that you can try to find clones that are willing to play nice because they're willing to essentially hold your little amoeba hand. I imagine somebody out there who actually studies amoeba is like cringing at that explanation. But, but then the other thing that you might want to do is preferentially try to find your kin. Right? So maybe it would be better if your slug had a million cells in it or something.
35:20 Daniel Whiteson? Right.
35:21 Kelly Weinersmith? But if as many of those cells as possible could be the exact same clone as you, then you're going to do much better than if you've got, you know, you and then the clone that you know cheats.
35:32 Daniel Whiteson? Right.
35:33 Kelly Weinersmith? Making up 50%.
35:34 Daniel Whiteson? And do we know why they do better when they're all the same clone? Do they just all swim the same way? Or how does that work?
35:40 Kelly Weinersmith? Yeah, we don't. That's a great question. We don't know exactly, but it could be things like, you know, they're all moving at the same speed or they're not like trying to jockey for the best position. They're just kind of moving forward.
35:54 Daniel Whiteson? Less chaos.
35:55 Kelly Weinersmith? Yeah, less chaos. And so the, but that's just like a hand wavy guess. We don't actually know.
35:59 Daniel Whiteson? Okay, interesting.
36:00 Kelly Weinersmith? Mm hmm. Okay, so they did some experiments to try to figure out if amoeba could essentially find their kin. And what they find is that if you put amoeba in trays together, the more distantly related the amoeba are, the less likely they are to come together and end up in the same slug.
36:21 Daniel Whiteson? Really?
36:22 Kelly Weinersmith? Yeah. So it does seem like to.
36:23 Daniel Whiteson? So they can do it?
36:24 Kelly Weinersmith? Yeah, to some extent, they can say like, I mean, so if the clones are sort of close, they probably can't tell the difference. But when they get pretty far apart, they can say, all right, you are not exactly like me. I'm going to try to preferentially associate with my clones and like avoid you a little bit.
36:41 Daniel Whiteson? When you say far apart, you mean genetically?
36:43 Kelly Weinersmith? Yes, I mean genetically.
36:45 Daniel Whiteson? And so do we know how they do this? I mean, they're not running little PCR tests, right? Taking little samples from each other. There must be something on the outside of the amoeba, which is very sensitive to the genetic record that they're using as a signal.
36:58 Kelly Weinersmith? Yeah, so we don't know exactly what it is, but it could be something like, you know, they have those hands that reach out, but some of the hands are shaped a little bit different. And it's easier to hold the hand of a clone or an amoeba that's closely related than an amoeba that's much more distantly related, where over time, maybe the hand now has eight fingers instead of five, and it just kind of doesn't hold together as well.
37:19 Daniel Whiteson? I like to imagine that the amoeba all have like their own specialized little greeting, you know, like a secret handshake. And if you have the wrong genetics, you like do it wrong. You're like, no, you're supposed to high five, and then you're supposed to do a low five, and then whatever.
37:31 Kelly Weinersmith? Exactly.
37:32 Daniel Whiteson? So maybe that's how they tell who's who and who's from what neighborhood.
37:35 Kelly Weinersmith? Yeah, they've got little voices and they're trying to do like little codes and hold hands and make like your handshakes. And it's, yeah, that's probably what's happening.
37:42 Daniel Whiteson? All right. But here we're speculating, right? Because we have not identified this. We haven't seen this in action.
37:46 Kelly Weinersmith? That's it. That's exactly right. Yeah.
37:48 Daniel Whiteson? So we know that they can do it. We just don't know how.
37:51 Kelly Weinersmith? That's right.
37:51 Daniel Whiteson? That's fascinating. Yeah.
37:52 Kelly Weinersmith? Yeah. And so this was becoming this like huge story because like everybody wants to study kin selection and try to figure out like, well, how do you know who kin is? And how does that impact cooperation and cheating? And by everybody, I'm seeing your face. Your face is saying, I don't care. But in the field of behavioral ecology.
38:13 Daniel Whiteson? No, my face is saying, okay, biologists are fascinated by this. Tell me why.
38:18 Kelly Weinersmith? Well, because we want to know about like the evolution of cooperation. Like, we see a lot of cooperation in nature. How does this evolve? And how does it show up? And how do you resist cheating to keep these systems going? Right? Because if you have too many cheaters, then like, it doesn't make sense to cooperate anymore.
38:33 Daniel Whiteson? Okay, because of all the puzzles we've laid out. Right?
38:36 Kelly Weinersmith? Yeah, exactly. Because of all the puzzles we've laid out. So the Strassman and Queller labs were like, well, what we really want to know is what do these lollipops, these fruiting bodies, look like in the wild? Like, if you collect one in the wild, is it all the same clone? Is it a bunch of different clones? Like, how do we make our lab results relevant to what's happening in the field? We need that baseline. And so they kept talking to amoeba experts who were like, you are never going to find them in the field. They're these teeny tiny little stalks, and none of us. Must have been able to find them.
39:09 Daniel Whiteson? Wait, but how do we know they exist? If how did people even know to make them in the lab if they'd never seen them in the wild?
39:15 Kelly Weinersmith? Well, probably I'm guessing because somebody forgot to put more bacteria on a plate one day. And they were like, oh, what's going on? There's a slug and now there's a fruiting body and you can reliably get them to do it in the lab over and over and over again.
39:26 Daniel Whiteson? Oh.
39:27 Kelly Weinersmith? Uh, and so they were like, this must be a thing they also do in nature.
39:30 Daniel Whiteson? So this was discovered first in the lab?
39:32 Kelly Weinersmith? Yeah.
39:33 Daniel Whiteson? Wow, that's incredible. I thought we knew about this. We'd seen it in the wild and people recreated it in the lab.
39:38 Kelly Weinersmith? Well, that's what I would have guessed too. And maybe some people had seen it, but like most of the community of people who study amoeba were telling Joan Strassmann and her husband, David Queller, you're probably not going to find it in the field. But they were like, you know what? We're field biologists. And when someone says you'll never find it, there's nothing that makes us want to go out in the field more than someone saying that. And so they went out and they thought to themselves, okay, they eat bacteria, but what you're looking for is a stage where there's not a lot of bacteria anymore. And so now they need to go somewhere else. We're looking for old poop.
40:11 Daniel Whiteson? Hold on. Wait, you got to back up because you said they. And sometimes you're referring to the amoeba and sometimes you're referring to the biologists.
40:18 Kelly Weinersmith? Oh, well, biologists and amoeba are interested in finding old poop. And so the amoeba, you know, when they have fresh poop, there's loads of bacteria there, just like you and your bacteria are collaborating on dinner. But you're going to leave them behind the next day. Deer and bacteria are collaborating on some leaves. And then the deer leave them behind and then the bacteria become food for amoeba.
40:42 Daniel Whiteson? Right.
40:42 Kelly Weinersmith? And then at some point, the amoeba have eaten all of the good bacteria. And now the deer poop is just not as delicious anymore. And they want to try to find a new, fresher deer poop. And so they went out looking for old deer turds.
40:58 Daniel Whiteson? How glamorous is biology, really?
41:00 Kelly Weinersmith? So glamorous.
41:02 Daniel Whiteson? Not even fresh deer turds, aged, aged deer turds.
41:06 Kelly Weinersmith? Like a fine wine.
41:08 Daniel Whiteson? Yeah.
41:08 Kelly Weinersmith? That's right. But, but they found them. They found a bunch of these like apparently impossible to find fruiting bodies by finding old turds.
41:19 Daniel Whiteson? Okay.
41:19 Kelly Weinersmith? But we're going to take a break. And when we get back, I'm going to tell you how related the amoeba were on the fruiting bodies on the turds.
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45:12 Daniel Whiteson? All right, we're back. And Kelly has already done the amazing, the near impossible, which is to get us all interested to know what is on Old Deer Turds.
45:22 Kelly Weinersmith? Oh man, you know, I gotta be honest. Usually I'm excited about what is in Old Deer Turds because that's where you find the parasite eggs. But now I'm also excited about what is on Old Deer Turds. And the answer is the amoeba who have gone through the slug stage and have now made that lollipop shaped fruiting body. When you look at how related they are to each other. It can go from zero, which is like completely unrelated. Like you run into somebody on another continent. You're like, we're really not very related.
45:50 Daniel Whiteson? Wait, how can they be zero? We had this whole episode where we talked about the common ancestors and percentage of DNA that's shared and like chimpanzees and humans are like 98% or whatever. So how can it be zero? What do you mean by zero?
46:03 Kelly Weinersmith? Well, so you might remember that Nathan Lentz explained that we share a lot of genes with chimpanzees. But what we're talking about in this situation is which exact genes do you share? So for example, if you have an identical twin, then all of your genes are the same. You got the same set of genes from your mom and the same set of genes from your dad. But your brother got 50% of their genes randomly from mom, 50% of their genes randomly from dad. And you also got 50% of the genes randomly from mom, 50% of the genes randomly from dad. And when that all plays out, you and your brother, for example, probably have 50% of pretty much the exact same gene copies because you got them from the same people, which is to say your parents.
46:47 Daniel Whiteson? I see. Right.
46:48 Kelly Weinersmith? Whereas if we were somehow lucky enough to clone Daniel, you and the Daniel clone would have a relatedness of one.
46:55 Daniel Whiteson? Right. I see.
46:57 Kelly Weinersmith? Okay.
46:57 Daniel Whiteson? And so you and I probably have a relatedness of what?
47:00 Kelly Weinersmith? Uh, probably pretty close to zero.
47:01 Daniel Whiteson? Okay.
47:02 Kelly Weinersmith? Yeah.
47:03 Daniel Whiteson? All right. So if Daniel amoeba meets Kelly amoeba in the wild, we're like, whoa, get away from me.
47:08 Kelly Weinersmith? Well, except I think I'd be like, I see within you a fellow altruist. And so maybe we would cooperate.
47:15 Daniel Whiteson? Let's start a podcast.
47:16 Kelly Weinersmith? That's right. That's right. That sounds like fun. Let's wear the same shirt on May 13th and dress like twinsees. Okay. So, so first of all, the answer is that some of the fruiting bodies that they picked up had a relatedness of one. So it was all the same clone.
47:34 Daniel Whiteson? Oh.
47:34 Kelly Weinersmith? Somehow they were associating with just similar clones. But on average, across all of the fruiting bodies, the relatedness was about 0.86, which means on average, they were associating with the same clone, but there were some other clones sprinkled in. But they- We're doing a pretty good job of making sure that like they were associating with very, very, very, very, very close relatives.
47:59 Daniel Whiteson? And that makes sense because we know that they can do this, that they can select their relatives, even if we don't know how they're doing that.
48:05 Kelly Weinersmith? Right. But it was, when we saw it in the lab, it was pretty weak. So it wasn't like they were a hundred percent excluding. They would still make slugs with other individuals, especially if they were kind of closely related. And so it was actually kind of hard to see these results and know the extent to which they seemed to be able to choose to hang out with the same clone in the lab. And that effect was pretty weak. And so it didn't explain, how do you get such a high relatedness in the fruiting body? And the answer, it appears, is one that, to be honest, is like, not super satisfying as, as from like a framework perspective, because you want it to be like, oh, our, their kin selection framework, we get all the support.
48:49 Kelly Weinersmith? But the answer seems to be, if you put amoeba in like a circle in a dish, and you let them grow out from there, just based on the way that they grow, the farther out from the circle, the more likely you are to be surrounded by the exact same clone, because it just starts like replicating and replicating and replicating and moving out from one location.
49:08 Daniel Whiteson? It's a geometric argument, basically.
49:10 Kelly Weinersmith? It's a geometric argument. Yeah. So like, if you imagine a pizza, and each slice is a clone, and they started like in the center. You know, like sometimes when you get a pizza, they've got that thing that looks like a little stool in the middle.
49:20 Daniel Whiteson? Yeah, a little stand. Yeah. Don't say stool when you're talking about pizza.
49:25 Kelly Weinersmith? Don't get squeamish on me now, Daniel. And so if you put them in the center where the stool is, wait, what did you tell me to call it?
49:33 Daniel Whiteson? That's a little stand. It's to hold up the box.
49:35 Kelly Weinersmith? Yeah, I know what it does. I know what it does. I eat a lot of pizza. So if you put, if you put the bacteria in the middle where the stand is, they grow out from there. And when they grow out from there, like if you're looking at the middle of a slice of pizza, the middle of that slice of pizza is probably going to have just about all the same clones, based just on the way they grew out from the center. And so when they start to run out of food and they send that signal, hey, guys, it's time to form a slug because we're running. Out of food, they're mostly talking to their relatives.
50:05 Daniel Whiteson? Yeah. So the, the area of each blob grows faster than its circumference. And so the ratio of area to circumference grows, which means that on average they're further away from a boundary.
50:17 Kelly Weinersmith? That sounds right.
50:18 Daniel Whiteson? Yeah. It's just a simple geometric argument. Cool.
50:21 Kelly Weinersmith? Simple geometric argument. Yes, exactly. So elementary, my dear Watson. And so.
50:25 Daniel Whiteson? Well, it's for the same reason that like elephants have a larger volume to surface area ratio than ants do, right? The insides grow faster than the surface does. And here the like boundary grows more slowly than the inside. And so on average, if you pick an amoeba, it's going to be further from the boundary as the circle grows.
50:42 Kelly Weinersmith? Yeah.
50:42 Daniel Whiteson? Yeah, that's cool.
50:43 Kelly Weinersmith? Yeah, right. And so maybe they do a little bit of discriminating, like if, if you find yourself closer to the edge of a slice and you're surrounded by clones that aren't closely related, maybe they are able to do a little bit to try to edge their slug to be a little bit more made up of their own type of clone.
50:59 Daniel Whiteson? But you don't have to do that much. If you get it kind of right in the beginning, then it supports itself.
51:04 Kelly Weinersmith? Yeah, exactly. Right. And so this is like pretty exciting that cooperation is arising to a large extent because of random spatial things that happen when you end up being like blown into a new environment and you spread from that central location. It just kind of turns out you have your family nearby. And so it's easy to associate and work with family, which benefits cooperation.
51:26 Daniel Whiteson? Yeah. Well, that's really cool that all you need is like a little bit of selective pressure to get the family members nearish each other. And then the geometry encourages it, right?
51:36 Kelly Weinersmith? Yeah.
51:36 Daniel Whiteson? Instead of mixing it all up.
51:37 Kelly Weinersmith? Totally. Yeah. And then this lab did this really amazing evolution experiment where essentially they took the amoeba and they forced them to make slugs with distantly related individuals. And then over many, many generations, they looked to see what happened. And what they found was that over many, many generations, if you find yourself in a slug with clones that are not closely related to you, then you will sometimes get individuals that are obligate cheaters, which is to say, if they get into your slug, they will never end up in the stalk. They cannot make stalk. But they can put themselves in the fruiting body. And you only get these obligate cheaters in the lab under these conditions.
52:19 Kelly Weinersmith? And so it looks like being able to work with closely related individuals is great for cooperation. But when you force them to work with individuals that are not closely related, cheating pops up more and more and more until you get some clones that can't even cooperate anymore. Cooperation like, you know, is lost in those clones.
52:39 Daniel Whiteson? Because the whole slug only happens because of cooperation. So if everybody is cheating, then it just doesn't even come together, right? Everybody's sitting at the white meat side of the table and there's no chairs.
52:50 Kelly Weinersmith? Yeah, I know. Isn't that sad? It's so sad. It's so sad. But, but, you know, these amoeba that have to cheat, if they're in an environment where there's not a lot of food, they're just in a ton of trouble because they can't make slugs on their own. They can't make fruiting bodies on their own. But as long as there's individuals that they can cheat off of, then they do okay. But anyway, so the evolution of cooperation depends on being able to associate with family members. And the more that association breaks down, the worse the cheating seems to get.
53:18 Daniel Whiteson? Wow, cool. And so what is the sort of cutting edge of research right now? Like, what are folks doing other than hunting for even older deer poop?
53:28 Kelly Weinersmith? Which is an exciting thing to be doing. But so, so one, you know, one of the things that they're doing is trying to figure out, why don't we see chimeras like this more often? So why don't we see more organisms cooperating because of these like spatial dynamics or whatever? Also, there's questions about are similar things happening in biofilms? So I asked Katrina, you know, when there's biofilms, are there individuals that are cheating to try to be in like the center of the biofilm where the antibiotics are less likely to be able to get to? And she was like, there's probably someone working on that. And I, I think that that's like, they're moving into biofilms to try to understand cooperation and cheating in biofilms where you also get a lot of different kinds of organisms coming together to share a common like cause that's supposed to help all of them.
54:11 Kelly Weinersmith? So trying to figure out what's happening there is a big question. And then they also discovered this really cool thing where like, okay, so they've got these plates. And after the fruiting body. Like after the amoeba go off and like start new colonies, they'll put them on plates and sometimes they put them on a plate that had no bacteria. So no food because they just kind of, you know, we're leaving them there for a little while. And then on some of the plates, bacteria started growing anyway. And they were like, that's weird. And then they noticed that bacteria kept growing on plates with particular clones, but it wasn't growing on plates with other clones.
54:48 Daniel Whiteson? Okay.
54:49 Kelly Weinersmith? And what they discovered was that some clones actually have the ability to bring some bacteria with them so that when they get into the new environment, they can seed the new environment with delicious bacteria that they're good at eating. It's kind of like when we take cows with us from like one place to another so that we can be sure that we've got some good food when we get there or carrots or cucumbers or, you know, whatever.
55:11 Daniel Whiteson? Seeds, yeah.
55:12 Kelly Weinersmith? Or seeds, yeah, or seeds. And so some clones are able to carry their own food with them. And so they called those clones farmer clones.
55:22 Kelly Weinersmith? And after digging a little deeper, it turned out that the farmer clones were only able to carry bacteria with them if they were also carrying a different kind of bacteria that they couldn't eat. So this bacteria was living inside of them.
55:36 Daniel Whiteson? Wow.
55:37 Kelly Weinersmith? As a symbiont.
55:38 Daniel Whiteson? They have like a little garden inside of them.
55:39 Kelly Weinersmith? Yeah, they've got, sure, yeah, garden. They've got like a little, I think what was really happening is that they have immune cells and those immune cells have encapsulated these bacteria, but the bacteria have found a way to neutralize the immune cells. And now they just live in there long term.
55:53 Daniel Whiteson? Wow.
55:53 Kelly Weinersmith? And these bacteria that live inside of the amoeba are able to give their amoeba host the ability to carry food with them from one environment to another environment. And they essentially benefit both of them by making sure that when they go into an environment, if it happens to not have a lot of food, that's all right, they brought some food with them.
56:12 Daniel Whiteson? Fascinating, so it benefits the bacteria to be brought along and then basically bred for food because they get to be alive. This is like, it's good for cattle to be a food crop because then there's lots of cattle?
56:24 Kelly Weinersmith? No, not quite. Okay, so my mistake, I'm talking about two different kinds of bacteria. So there is bacteria one, which is inedible and lives inside of the amoeba. And then there's bacteria two, which are the cows. And the cows are able to be carried only when the inedible bacteria are inside. And we don't know why they give the amoeba the ability to bring cows with them.
56:51 Daniel Whiteson? Okay.
56:52 Kelly Weinersmith? But somehow they do. And this ends up being really good for both the amoeba and the inedible bacteria. When they go to an environment where there's not a lot of food. But if they go to an environment where there is a lot of food, then it seems it's not good that they spent the energy to try to carry the bacteria with them. But anyway, right now, the lab is working on what is happening with these farmers? When is it beneficial to bring food with you? How the heck does this one inedible bacteria living inside of the amoeba allow it to bring cows to foreign locations? And so now, now they're digging into that question. So now they're looking at interactions between various players and how stable they are over time.
57:33 Kelly Weinersmith? All right, so the, the cutting edge to sort of bottom line and eventually finally answer your question is that they're trying to get a general handle on what the results in dicti mean for other groups of organisms that come together to collaborate.
57:48 Daniel Whiteson? Do these answers generalize or is it specific to these amoebes?
57:51 Kelly Weinersmith? Right, exactly. And now they're trying to understand symbioses in general more. So symbiosis is when you have multiple different organisms working together. And so why is this bacteria helping the amoeba? And just kind of looking at those interactions long term.
58:05 Daniel Whiteson? Wow, it seems like there's such a rich set of mysteries here, right? Of like how evolution works, not just at the organism level, but at the population level, how those things interact. Fascinating.
58:16 Kelly Weinersmith? Yeah, what I love is that when I got into this field, I wanted to study like cheetahs and lions and like the big charismatic megafauna. But at the end of the day, like, yes, you can do a lot of cool behavior work by like sitting in a beautiful savanna and watching them. But at the end of the day, like, the evolution experiments that this lab was able to do by having an organism that reproduces quickly, where you can really control like what the clones are doing and what their environments are like, and then you can check those results against what's happening in the field. Like, in the last few decades, I, you know, I read through most of the papers that the lab has written on this species in the last couple of days. The amount of ground they've been able to cover in those decades is incredible. And so I know it's, it's exciting to think about working on cheetahs.
58:59 Daniel Whiteson? Cheetah babies are pretty cute.
59:01 Kelly Weinersmith? They're really cute. And these amoeba, probably much less cute, especially if you're going to find deer poop. But like, they've really been able to answer some interesting questions and understand a lot about this system by having a system that just is kind of easier to work with in the lab.
59:14 Daniel Whiteson? Yeah, and there's just so much biology happening at so many scales. It's mostly invisible to you what's going on microscopically, but like, it's a war down there.
59:23 Kelly Weinersmith? Yeah, it is. And like, how cool to have been working in the system for decades and then be like, wait a minute, some of those clones always are associated with contamination on the agar plates afterwards. Maybe they're bringing bacteria with them. And so it's just also the benefit of like, working with an organism for many, many years and just staring at it and like, being open to what it might be showing you that you had missed before.
59:46 Daniel Whiteson? Yeah.
59:47 Kelly Weinersmith? Very exciting.
59:48 Daniel Whiteson? Very exciting discoveries, somehow compensation for not getting to see baby cheetahs.
59:51 Kelly Weinersmith? I, you know, I think that they really enjoy it, but Joan Strausman also writes books about birding. And so you can check out her books, Slow Birding and The Social Lives of Birds, which I recommend. She does amazing work on birds as well.
1:00:03 Daniel Whiteson? And you dug into this topic because it's fascinating, not just as personal penance for your flubbed interview from 15 years ago.
1:00:10 Kelly Weinersmith? No, to be honest, I, I kind of wanted to not cover this topic because I didn't want to have to listen to that interview, but I knew there was a lot of good information in there. And so I, anyway, I did anyway, but I, I actually did this one because see Dave in our Discord channel. Asked for it, and I give the listeners what they want. So let's go ahead and see if C. Dave feels like he's learned everything he wanted to know about the curious lives of social amoeba. Thanks, Daniel and Kelly. Sorry we're such a traumatic topic for you. Involving self-sacrifice for an unrelated neighbor seems like such a paradox, but this discussion sort of really makes it clear how that happens. Your point about shrinking evolutionary timescales down to human timescales is really brilliant. Anthropomorphing aside, it's a little depressing
1:00:52 Kelly Weinersmith? to know that altruism only evolves to help those similar, and that obligate cheaters can prosper too. The farmer's symbiotic cooperation with the parasitic bacteria bringing a third species along is actually really uplifting. My only question is, where's the cannibalism for my bingo card? Holy cow, Dave. I can't believe I forgot to get back to cannibalism in the episode. Okay, so the point there was if you take different clones of the amoeba, and you compete them against one another, there's usually a winner and a loser. And the winner is more likely to end up in the top of the lollipop. So they're more likely to be able to end up in the part that gets to survive and go on to start new populations. And the losers are more likely to end up in the stalk, the like, you know, stick of the lollipop. But when
1:01:36 Kelly Weinersmith? you count up the amoeba that are present at the end of the experiment, it looks like some of the losers not only were more likely to end up in the stalk, but they also are just present in lower numbers than you would expect them to be. It's like some of them died or got lost along the way. So one of the ideas is that as the slug moves along, just like a real slug, it leaves something like a slime trail. So maybe the losers are more likely to sort of fall off along the way and get left behind. Or the authors hypothesized that maybe there's some cannibalism going on with the winner amoeba clones eating some of the loser amoeba clones along the way. This was just a hypothesis. It didn't get tested. But as soon as I saw anything related to cannibalism, I was like, I have to mention
1:02:20 Kelly Weinersmith? that on the show. And then somehow, I forgot. So thank you for keeping us on track.
1:02:26 Daniel Whiteson? All right, Kelly, thank you for taking us on this deep dive into the lives of amoebes. Really fascinating stuff. Great to know that these little farmers work together to make life better for all of them.
1:02:37 Kelly Weinersmith? And if they do it, why can't you? Although actually, I guess the answer would be, you should specifically help your family and try to keep everyone else out. So forget what the amoeba are doing, but they cooperate, and that's me.
1:02:47 Daniel Whiteson? So everybody make sure to be nice and don't just grab the spot at the top of the Thanksgiving table. There's enough for everybody.
1:02:55 Kelly Weinersmith? But do avoid the dark meat. Until next time.
1:03:05 Daniel Whiteson? Thanks, everybody for listening. Please go and do us a favor and rate the show on whatever podcast app you're using. It really helps people find us.
1:03:13 Kelly Weinersmith? Daniel and Kelly's Extraordinary Universe is edited by the amazing Matt Kesselman.
1:03:18 Daniel Whiteson? He really is a wizard. You can also find us online on Blue Sky, Instagram and X, D and K Universe. Come engage with us.
1:03:28 Kelly Weinersmith? You can email us at questions at danielandkelly.org. We really do want to hear from you.
1:03:33 Daniel Whiteson? And you can find our website, www.danielandkelly.org, where you'll also find an invitation to join our Discord, where everybody comes and talks about the amazing universe.
1:03:44 Kelly Weinersmith? And we also have the most amazing moderators. This is an iHeart Podcast. Thanks for joining us.
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