WEBVTT - Zombie ants 0:00:07.840 --> 0:00:11.360 The fungus known as Ohio cortceps may be the most 0:00:11.480 --> 0:00:14.400 famous fungus in pop culture right now. I know it's 0:00:14.440 --> 0:00:17.000 a lobar, but still it's pretty cool. The Girl with 0:00:17.040 --> 0:00:19.919 All the Gifts, The Last of Us and a host 0:00:20.720 --> 0:00:24.640 of other books, movies, and video games feature this behavior 0:00:24.760 --> 0:00:29.120 manipulating fungal pathogen. But what does it really do? How 0:00:29.120 --> 0:00:32.720 do the zombie ants behave? And what do we know 0:00:32.800 --> 0:00:36.239 about how the fungus hijacks ant behavior? And Yes, at 0:00:36.280 --> 0:00:38.960 the end of the episode, I'll speculate on whether Ofio 0:00:39.000 --> 0:00:42.120 coort aceps could jump from ants to humans hijacking or 0:00:42.159 --> 0:00:46.839 behavior along the way. Welcome to Daniel and Kelly's Manipulated Universe. 0:01:00.160 --> 0:01:02.960 Hi. I'm Daniel. I'm a particle physicist, and I like 0:01:03.000 --> 0:01:04.640 to think of myself as a fun guy. 0:01:05.480 --> 0:01:07.479 You know, Daniel, you have made that joke before. 0:01:08.080 --> 0:01:08.959 It's too good? 0:01:09.640 --> 0:01:12.880 It is, It is good, It's good. I'm Kelly Wider Smith, 0:01:12.959 --> 0:01:14.039 and I'm a fun gal. 0:01:18.319 --> 0:01:21.400 And today we're talking about how funguses make us friends, 0:01:21.680 --> 0:01:26.280 or make us more fun no, or make us whact 0:01:26.319 --> 0:01:27.840 weird and climbed to the tops of. 0:01:27.800 --> 0:01:32.640 Things or something else entirely Yes, how ants get manipulated 0:01:32.680 --> 0:01:36.000 by a fungal pathogen, but probably well, wait till the end, 0:01:36.040 --> 0:01:37.319 we'll see what we think about people. 0:01:37.440 --> 0:01:39.959 I do like the idea that some of our weird 0:01:40.000 --> 0:01:42.600 behavior can be attributed to some part of us that's 0:01:42.680 --> 0:01:45.360 not really part of us. You know, that you can say, oh, 0:01:45.400 --> 0:01:47.040 that's just the fungus in my brain. 0:01:47.360 --> 0:01:49.760 Yeah. Absolutely. So. When I started my PhD, I was 0:01:49.800 --> 0:01:53.000 studying why organisms behave the way they do, so I 0:01:53.040 --> 0:01:56.360 was into animal behavior and I came across the Toxoplasma 0:01:56.400 --> 0:01:59.600 Gandhi literature, where that parasite that lives in our brains 0:01:59.640 --> 0:02:02.920 is a sociated with weird behaviors. And I got absolutely 0:02:02.960 --> 0:02:06.040 hooked on this idea that not all of our behaviors 0:02:06.080 --> 0:02:09.320 are attributable to our decisions, that maybe it's like a 0:02:09.320 --> 0:02:12.560 group effort the person who we end up being, and 0:02:12.560 --> 0:02:15.120 that you know, the microbes in our gut influence our 0:02:15.160 --> 0:02:18.240 behavior and the parasites in our brain influence our behavior. 0:02:18.280 --> 0:02:20.360 And I find this topic totally fascinating. 0:02:20.440 --> 0:02:23.079 But in some sense that's frame because it tells you, oh, 0:02:23.080 --> 0:02:25.519 it don't make all my decisions. In another sense that's 0:02:25.600 --> 0:02:27.400 terrifying because it's like, oh my gosh, I don't make 0:02:27.400 --> 0:02:30.359 all my decisions, and Katrina would probably be like, no, 0:02:30.480 --> 0:02:33.080 that is who you are. Your microbes are part of you. 0:02:33.800 --> 0:02:35.720 Yeah, No, I tind of agree with that take. But 0:02:35.760 --> 0:02:37.360 one thing that I think is fun is that one 0:02:37.400 --> 0:02:40.160 of the big names in the field that studies how 0:02:40.200 --> 0:02:44.320 Toxoplasma gandhia impacts human behavior, his name is Yaroslav Flagger. 0:02:44.560 --> 0:02:48.000 Apologies for my you know, forever bad pronunciations. He got 0:02:48.040 --> 0:02:51.120 into this because he was like, you know, I act 0:02:51.240 --> 0:02:54.600 kind of weird, sort of like not like other people. 0:02:54.680 --> 0:02:57.680 I wonder if I have a brain infecting parasite. And 0:02:57.720 --> 0:02:59.880 he gave himself a test and he did, and this 0:03:00.080 --> 0:03:02.920 set him off on the path of like wondering about 0:03:03.040 --> 0:03:07.240 how toxoplasmosis is associated with human behavior. It's an interesting question. 0:03:07.480 --> 0:03:09.280 Is it possible to have a fungus in your brain 0:03:09.360 --> 0:03:13.680 that makes you eat cookies too late at night? Can 0:03:13.720 --> 0:03:14.800 I blame that on somebody? 0:03:15.480 --> 0:03:18.400 Daniel? That is you? No, that's you, Daniel, that's you. 0:03:18.800 --> 0:03:22.000 And just for clarification, Toxoplasma gandhia is not a fungus, 0:03:22.040 --> 0:03:24.760 but there are a variety of different parasites that can 0:03:24.760 --> 0:03:25.560 live in human brains. 0:03:25.600 --> 0:03:28.360 Unfortunately, so if I do have a parasite, it's probably, 0:03:28.360 --> 0:03:30.520 like Daniel, stop eating cookies. Those are bad for you 0:03:30.560 --> 0:03:31.360 and bad for us. 0:03:31.560 --> 0:03:31.960 Yeah. 0:03:32.000 --> 0:03:34.400 Maybe, Wow, I'm overruling them. 0:03:34.440 --> 0:03:38.240 I don't know that cookie consumption as an implication of 0:03:38.440 --> 0:03:41.200 brain parasites has been studied thoroughly, So I don't want 0:03:41.200 --> 0:03:41.960 to go on the record. 0:03:42.800 --> 0:03:45.000 It's so easy to get to the edge of knowledge 0:03:45.000 --> 0:03:45.920 in biology. Wow. 0:03:46.680 --> 0:03:48.760 Yeah, we're not asking the right questions. 0:03:50.320 --> 0:03:52.880 Why does mainstream biology want to shut this question down? 0:03:53.000 --> 0:03:53.720 Kelly hmm. 0:03:55.400 --> 0:03:58.800 Yeah, I don't know, Daniel, not a great question, But 0:03:58.880 --> 0:04:00.000 you know, what is a great question? 0:04:00.320 --> 0:04:01.200 Give us a transition? 0:04:01.680 --> 0:04:04.280 Yeah, what is a great question is the question we 0:04:04.320 --> 0:04:05.240 asked our listeners. 0:04:05.680 --> 0:04:06.440 What was that? 0:04:06.440 --> 0:04:11.520 That was? What is summit disease? And if you would 0:04:11.600 --> 0:04:13.600 like to answer questions for us, send us at an 0:04:13.640 --> 0:04:16.840 email at questions at Danielinkelly dot org and we'll add 0:04:16.880 --> 0:04:19.479 you to our list. So let's hear what our listeners 0:04:19.520 --> 0:04:22.720 had to say in response to what is summit disease? 0:04:23.320 --> 0:04:27.560 Summit disease is an affliction that occurs when you can't 0:04:27.600 --> 0:04:31.040 stop hiking to the top of mountains, and it causes 0:04:31.080 --> 0:04:33.320 you to neglect the rest of your life. I think 0:04:33.360 --> 0:04:35.360 it's a brain disorder that makes you way at dead 0:04:35.360 --> 0:04:39.960 bodies on the way up Nepalese mountains. The sickness individuals 0:04:40.160 --> 0:04:45.520 get when they are at a high altitude and climbing mountains, 0:04:45.560 --> 0:04:46.880 for example. 0:04:46.839 --> 0:04:50.240 I think you're referring to high altitude sickness. Mountain climbers, 0:04:50.400 --> 0:04:52.800 when they go up above a certain elevation, can get 0:04:53.320 --> 0:04:57.960 lack of oxygen, pulmonary edema, cerebral edema, et cetera. No bueno, 0:04:58.360 --> 0:05:02.080 this is a disease a similar to OCD. You have 0:05:02.160 --> 0:05:04.440 to walk around adding things together. 0:05:04.800 --> 0:05:07.880 I could be mistaken, but I believe it is when 0:05:08.040 --> 0:05:12.039 an avid climber gets the impulsive need to tell the 0:05:12.080 --> 0:05:15.080 people around them all of the mountains that they have summitted. 0:05:15.400 --> 0:05:18.080 It seems like summer disease could be when I go 0:05:18.320 --> 0:05:20.360 on top of a mountain and my fingers swell up 0:05:20.800 --> 0:05:21.520 and I get tired. 0:05:21.560 --> 0:05:23.359 Easier except for way way worse. 0:05:23.720 --> 0:05:27.360 Summit disease is when you, after a really long climb, 0:05:27.360 --> 0:05:30.280 get to the summit, and then the mountain gods invade 0:05:30.320 --> 0:05:31.760 your brain make you do bad stuff. 0:05:31.920 --> 0:05:32.279 I don't know. 0:05:32.680 --> 0:05:36.080 When you reach the summit of a mountain and you 0:05:36.160 --> 0:05:40.200 can't stop throwing up because you're so sick of looking 0:05:40.279 --> 0:05:40.880 at mountains. 0:05:41.160 --> 0:05:42.960 I think that's when you're hiking and you've each an 0:05:42.960 --> 0:05:45.640 altitude or an elevation where the air gets dinner and 0:05:45.720 --> 0:05:48.560 you start to get headaches and funauseous and stuff like that. 0:05:49.000 --> 0:05:51.400 So I also would have guessed something that happens to 0:05:51.440 --> 0:05:53.000 you at the top of Mount Everest. 0:05:53.240 --> 0:05:56.279 Yeah, that is a totally reasonable answer. We have a 0:05:56.400 --> 0:05:59.760 very smart audience, but actually this is something that happens 0:05:59.760 --> 0:06:02.880 to insects and not to humans. And I'll also note 0:06:02.880 --> 0:06:05.039 that I laughed out loud at the uh you have 0:06:05.080 --> 0:06:07.120 to walk around adding things together. It took me a 0:06:07.120 --> 0:06:09.520 second to put that together and be like, oh, some 0:06:10.120 --> 0:06:14.080 it some it adding, and I laughed out loud. So anyway, 0:06:14.160 --> 0:06:17.000 thank you for that moment of revelation there. 0:06:17.279 --> 0:06:19.559 Well, I love this opportunity to dig into the real 0:06:19.680 --> 0:06:23.880 science that's sort of underlying some Hollywood myths. You know, 0:06:23.920 --> 0:06:26.680 there are these fun stories you hear sometimes in science fiction, 0:06:27.160 --> 0:06:30.800 but often these are inspired by actual and really fascinating 0:06:30.920 --> 0:06:34.000 on their own stories of what's going on out there 0:06:34.040 --> 0:06:37.760 in nature. So tell us, Kelly, what is the story 0:06:37.839 --> 0:06:40.400 that inspires all these Hollywood tropes? 0:06:40.640 --> 0:06:43.320 Well, So let's start with what is summit disease. And 0:06:43.440 --> 0:06:45.880 Summit disease is a thing that happens to a lot 0:06:45.920 --> 0:06:49.000 of different insects that are infected by fungus or by viruses. 0:06:49.080 --> 0:06:51.560 And the deal is that either the fungus or the 0:06:51.640 --> 0:06:54.320 virus gets an insect to climb high, and then it 0:06:54.360 --> 0:06:56.599 gets the insect to stay there instead of like coming 0:06:56.600 --> 0:06:59.279 down for the night. And then they like cling in 0:06:59.320 --> 0:07:02.479 some way and they stay up high and from that 0:07:02.600 --> 0:07:07.080 location they then die and they rain infectious particles down 0:07:07.279 --> 0:07:09.320 on their other insects below. 0:07:09.400 --> 0:07:10.480 They like explode. 0:07:10.840 --> 0:07:14.160 Uh you know, explode might be over selling it a little, 0:07:14.360 --> 0:07:17.720 but like, so, for example, there's a virus that infects caterpillars, 0:07:17.720 --> 0:07:20.280 and caterpillars go up during the day to like eat leaves, 0:07:20.520 --> 0:07:22.520 and then at night they usually come down and they 0:07:22.600 --> 0:07:25.160 like hide. But this when they're infected by this virus, 0:07:25.160 --> 0:07:27.320 they climb up and they stay there and then they 0:07:27.360 --> 0:07:30.320 die and they sort of liquefy and they rain virus 0:07:30.360 --> 0:07:32.680 particles down on the caterpillars that are below. 0:07:34.640 --> 0:07:37.840 They drip guey infected caterpillar down they do. 0:07:38.000 --> 0:07:40.920 Yeah, what a weather forecast that's oh yeah, cloudy with 0:07:40.960 --> 0:07:46.200 the chance of virus soup caterpillar bits. That's right, gross, 0:07:47.200 --> 0:07:50.000 But this also happens. There are like quote unquote zombie 0:07:50.000 --> 0:07:52.680 flies that are infected by a fungus and they'll climb 0:07:52.800 --> 0:07:55.000 up and they'll even like they'll climb up and then 0:07:55.000 --> 0:07:57.360 they'll spread their wings out to the side so that 0:07:57.400 --> 0:08:00.480 when they die, the fungus can come out of their 0:08:00.480 --> 0:08:02.200 back and their wings don't get in the way. And 0:08:02.240 --> 0:08:05.000 that one does it sort of like shoots like cannonballs 0:08:05.000 --> 0:08:07.760 out of their back down at the like flies below. 0:08:07.880 --> 0:08:10.240 And so, oh my gosh, this is a pretty common 0:08:10.280 --> 0:08:14.560 strategy you see in viruses and fungus that infect insects 0:08:14.560 --> 0:08:16.720 that want to go on to infect more insects. 0:08:16.920 --> 0:08:20.280 It's fascinating because you say it does this so that 0:08:20.400 --> 0:08:22.880 this other thing happens, which implies that there's some sort 0:08:22.880 --> 0:08:25.080 of high level decision making. But I know it's all 0:08:25.160 --> 0:08:30.600 like low level mechanistic blind evolution. So I'm curious to 0:08:30.640 --> 0:08:33.000 hear how all that comes together and how the whole 0:08:33.040 --> 0:08:35.920 process comes together. You know, it's one of these examples 0:08:35.920 --> 0:08:38.360 of like a complicated thing where you need lots of 0:08:38.400 --> 0:08:41.760 pieces all together to accrue the benefit, which always makes 0:08:41.760 --> 0:08:44.680 me wonder how it came together in the intermediate stages. 0:08:44.880 --> 0:08:47.040 Yeah, and this is why the zombie ant system is 0:08:47.080 --> 0:08:50.200 one of my favorite systems to study. So this phenomenon 0:08:50.240 --> 0:08:54.640 where some parasite or pathogen hijacks the behavior of its 0:08:54.679 --> 0:08:57.480 host so that the host is doing something that benefits 0:08:57.480 --> 0:09:02.520 the parasite, we call this manipulation, and it's really tempting, 0:09:02.520 --> 0:09:04.520 and we've talked about this in other episodes. It's really 0:09:04.600 --> 0:09:07.160 tempting when you see a host behaving weirdly to be like, oh, 0:09:07.200 --> 0:09:10.040 that's a manipulation that must benefit the parasite in some way. 0:09:10.520 --> 0:09:12.920 But while it's easy to come up with a story, 0:09:12.960 --> 0:09:14.839 it's harder to test that. And every once in a 0:09:14.920 --> 0:09:16.840 while we'll have a story where it sounds like the 0:09:16.880 --> 0:09:19.480 pathogen was benefiting, but when you look into it, it's 0:09:19.520 --> 0:09:23.199 not so. Mosquitos when they're infected by malaria, right after 0:09:23.200 --> 0:09:26.600 they get infected by malaria, they bite less, and there's 0:09:26.720 --> 0:09:29.760 a period where after the mosquito takes a blood meal 0:09:29.800 --> 0:09:33.520 that has malaria, that malaria is sort of maturing and 0:09:33.600 --> 0:09:36.520 can't transmit yet. So if the mosquito took a blood 0:09:36.559 --> 0:09:40.920 meal and got slept by a hand, then the malaria 0:09:40.960 --> 0:09:42.960 would die, and so that wouldn't be good. You know, 0:09:43.000 --> 0:09:45.640 in a very anthropomorphic way, the malaria quote unquote doesn't 0:09:45.679 --> 0:09:48.520 want the mosquito to get killed or to take blood 0:09:48.520 --> 0:09:49.640 meals at that point. 0:09:49.480 --> 0:09:51.840 While it's still developing and preparing. 0:09:51.520 --> 0:09:53.720 That's right. But once it's ready, once it's in the 0:09:53.760 --> 0:09:57.240 mosquito salivary glands and could transmit to a human, those 0:09:57.280 --> 0:10:01.040 mosquitos start biting even more. So this was thought of 0:10:01.200 --> 0:10:05.840 as manipulation. The parasite is protecting the mosquito and itself 0:10:06.120 --> 0:10:08.640 until it can transmit, and then once it transmits, it 0:10:08.679 --> 0:10:11.079 gets the mosquito to bite a lot more. And that 0:10:11.280 --> 0:10:13.080 really sounds like it would be good for the mosquito. 0:10:13.320 --> 0:10:15.440 It's a good story, it's a great story. But it 0:10:15.520 --> 0:10:19.400 turns out that if you activate the mosquito's immune response 0:10:19.480 --> 0:10:23.360 by for example, killing bacteria and then putting those dead 0:10:23.440 --> 0:10:27.200 bacteria into the mosquito, it will do the same thing. 0:10:27.320 --> 0:10:29.360 Even though it doesn't benefit that bacteria. 0:10:29.400 --> 0:10:31.760 That's right. Where Yeah, the bacteria are dead, they're just 0:10:31.920 --> 0:10:35.720 making the mosquito's immune system activate, and this is what 0:10:35.760 --> 0:10:38.080 the mosquito does. So it could be like when the 0:10:38.080 --> 0:10:40.680 mosquito's immune system is activated, it just kind of wants 0:10:40.679 --> 0:10:42.959 to hunker down. It's not as fast, it's feeling kind 0:10:43.000 --> 0:10:45.760 of crummy. It's just taking a nap before it's ready 0:10:45.760 --> 0:10:49.240 to go again. And so that's probably not manipulation. It 0:10:49.280 --> 0:10:51.320 doesn't look like the malaria is doing that. That's something 0:10:51.320 --> 0:10:52.520 that's driven by the mosquito. 0:10:52.720 --> 0:10:54.880 Could still be in response to the malaria. Right when 0:10:54.880 --> 0:10:57.400 it gets infected, it does this, and the malaria can 0:10:57.480 --> 0:11:00.200 benefit from it. You're just saying it's not something that 0:11:00.240 --> 0:11:03.679 the malaria has specifically engineered to benefit itself. It's something 0:11:03.720 --> 0:11:06.520 the mosquito is already doing or would otherwise have done. 0:11:06.920 --> 0:11:08.040 Fascinating exactly. 0:11:08.080 --> 0:11:10.160 Yeah, So trying to figure out who's driving the change 0:11:10.160 --> 0:11:13.280 in the behavior and how it actually benefits is much 0:11:13.320 --> 0:11:15.640 harder than coming up with the initial story. Yeah, and 0:11:15.679 --> 0:11:17.760 so what I love about the zombie ants is that 0:11:17.840 --> 0:11:20.160 this system has been studied in quite a bit of detail, 0:11:20.200 --> 0:11:22.720 and so we're actually starting to nail down the various 0:11:22.760 --> 0:11:23.920 pieces of what's happening here. 0:11:24.040 --> 0:11:26.280 Well, that reminds me of our conversation with Capo hen 0:11:26.320 --> 0:11:28.720 and when we were talking about science and storytelling and 0:11:28.760 --> 0:11:32.320 how much of science is storytelling is saying this happens 0:11:32.400 --> 0:11:35.240 because of that, because of this other thing, and sometimes 0:11:35.280 --> 0:11:38.920 the statistics or the mechanics of it don't always support that. 0:11:38.960 --> 0:11:42.280 It's just we are trying to extract stories because stories 0:11:42.320 --> 0:11:43.160 make sense to us. 0:11:43.440 --> 0:11:45.200 Yeah, and I think sometimes we get a little carried 0:11:45.240 --> 0:11:47.680 away with our stories and we don't necessarily have facts 0:11:47.679 --> 0:11:52.000 to support every piece of the story. And so this 0:11:52.080 --> 0:11:54.760 system is nice because almost every piece of the story 0:11:55.000 --> 0:11:57.120 has been dug into to some degree. 0:11:57.240 --> 0:11:59.480 All right, then carry us away to a story, Kelly 0:11:59.520 --> 0:12:01.960 tell us about manipulation of ants. 0:12:02.320 --> 0:12:06.560 Okay, you are a little ant walking around on the 0:12:06.600 --> 0:12:09.880 forest floor. Unbeknownst to you, you have stepped on a 0:12:09.880 --> 0:12:14.440 fungal spore. The fungus gets in between the cuticles and 0:12:14.720 --> 0:12:15.600 invades the body. 0:12:15.679 --> 0:12:18.880 Wait, I'm a little ant and I have cuticles still exoskeleton. 0:12:19.040 --> 0:12:21.160 I think they call that cuticle. I don't study ants. 0:12:21.200 --> 0:12:24.280 Man. What's the name of my aunt? Am I Dantiel? 0:12:27.360 --> 0:12:29.679 Yes, yes, you're Danchel. 0:12:29.440 --> 0:12:31.559 Walking around the forest with my little cuticles. 0:12:31.559 --> 0:12:36.640 Okay, so poor Danchel has picked up a fungus. Danchel 0:12:36.720 --> 0:12:40.720 doesn't realize that he's infected. Actually, if you're a forger, 0:12:40.760 --> 0:12:42.880 you're probably a female. So this anyway, this is not 0:12:42.920 --> 0:12:45.240 working great. But anyway, so the little ants, the little 0:12:45.280 --> 0:12:48.440 ant has gotten infected, doesn't realize it. It goes back 0:12:48.480 --> 0:12:51.040 to its nest. The nest mates don't seem to realize 0:12:51.040 --> 0:12:54.600 that it's infected either. But a couple weeks after it 0:12:54.640 --> 0:12:57.640 initially gets infected, it starts walking out of the nest. 0:12:57.720 --> 0:12:59.400 And this nest is up in a tree, and it 0:12:59.440 --> 0:13:02.200 starts rumbling down. We call it a drunk walk. So 0:13:02.280 --> 0:13:04.360 it sort of starts stumbling down the tree and then 0:13:04.360 --> 0:13:07.320 it walks along the forest floor and it climbs up 0:13:07.400 --> 0:13:09.720 a stalk and this is in the tropics. It climbs 0:13:09.840 --> 0:13:12.840 up a stalk or a stem of something to about 0:13:12.920 --> 0:13:16.679 twenty plus or minus two centimeters. This is happening at 0:13:16.679 --> 0:13:19.720 solar noon and on the north northwest side of the plant. 0:13:19.960 --> 0:13:23.520 It goes underneath a leaf, bites down with its mandibles. 0:13:23.559 --> 0:13:25.840 These are like the pinsy mouth parts it has, and 0:13:25.880 --> 0:13:28.240 then it will never move again and it dies. 0:13:28.520 --> 0:13:30.040 Wow. So it has to go all the way down 0:13:30.080 --> 0:13:32.600 the tree just to find the stalk to climb up. 0:13:32.679 --> 0:13:34.640 Yes, yep, just to find the stock to climb up. 0:13:34.720 --> 0:13:35.200 Fascinating. 0:13:35.280 --> 0:13:38.760 And then the ant dies and a stalk comes out 0:13:38.760 --> 0:13:41.280 of the side of its neck and it forms a 0:13:41.520 --> 0:13:44.160 ball at the sort of like top ish part of 0:13:44.200 --> 0:13:46.760 the stalk, and then fungal spores rained down on the 0:13:46.760 --> 0:13:48.760 forest floor and the cycle starts again. 0:13:48.880 --> 0:13:50.680 The stalk is not from the plant, it's some like 0:13:50.760 --> 0:13:51.719 weird fungal thing. 0:13:52.120 --> 0:13:54.160 Yeah, it's the fungus makes it so the fungus, now 0:13:54.160 --> 0:13:56.080 that the ant is dead, it starts using all of 0:13:56.080 --> 0:13:59.520 the ant's internal body parts and converting it into fungus 0:13:59.760 --> 0:14:02.720 and makes this stalk that rains fungal spores down, and 0:14:02.760 --> 0:14:03.800 the cycle starts again. 0:14:03.960 --> 0:14:06.440 This sounds like a science fiction horror movie. You're telling 0:14:06.480 --> 0:14:08.439 me this is happening on our planet all the time. 0:14:08.600 --> 0:14:10.920 Oh my it is. And okay, so what blows my 0:14:11.000 --> 0:14:13.600 mind is that that is so specific. Like one of 0:14:14.080 --> 0:14:16.880 one of Zach's gripes about me as a human being 0:14:17.200 --> 0:14:21.160 is that I am really bad at estimating distances, and 0:14:21.400 --> 0:14:22.840 like He'll be like, well, what's you know? Do it 0:14:22.840 --> 0:14:24.360 about two feet from here, and I'll be like, I 0:14:24.400 --> 0:14:26.320 have no idea what you mean, Like, I just I 0:14:26.360 --> 0:14:30.600 can't do that. Whereas this fungus by remote control is 0:14:30.640 --> 0:14:34.080 getting the ant to about twenty five centimeters plus or 0:14:34.080 --> 0:14:37.080 minus like two and a half centimeters. I think earlier 0:14:37.120 --> 0:14:39.160 I said it was twenty but it's more like twenty five, 0:14:39.240 --> 0:14:41.280 which is very specific. And so how does that happen. 0:14:41.360 --> 0:14:43.280 We're gonna get to our best guess right now at 0:14:43.320 --> 0:14:45.640 how that happens a little bit later in the show. 0:14:45.880 --> 0:14:47.640 But it's amazingly specific. 0:14:47.800 --> 0:14:48.080 Wow. 0:14:48.280 --> 0:14:50.640 But now it's worth mentioning that. Okay, that is a 0:14:50.680 --> 0:14:54.560 story from O fio cordus steps unilateralis And just to 0:14:54.680 --> 0:14:55.160 complete the. 0:14:55.200 --> 0:14:57.280 Loop, it rains it down on the forest floor and 0:14:57.360 --> 0:14:59.360 then the next ant can come along and pick it 0:14:59.480 --> 0:15:02.000 up in there goals and that's how it completes the cycle. 0:15:02.440 --> 0:15:06.840 Danchel, the she ants does pick up dante l Yeah, Dantel, 0:15:06.920 --> 0:15:09.400 that's right, picks up the fungus and the cycle starts again. 0:15:09.600 --> 0:15:11.400 Wow, all right, okay, And so the name of this 0:15:11.520 --> 0:15:13.680 fungus is some crazy Latin phrase. Yeah. 0:15:13.720 --> 0:15:17.440 So Ofio cordyceps unilateralis. The unilaterallysis refers to the fact 0:15:17.520 --> 0:15:20.480 that the stalk comes out of one side of the 0:15:20.520 --> 0:15:24.280 ant's head. And so opio coortceps is a genus. So 0:15:24.320 --> 0:15:27.000 there's a lot of different fungus species that are very 0:15:27.040 --> 0:15:31.040 closely related, and they infect different ant species, so they 0:15:31.080 --> 0:15:34.040 seem to specialize on different species. So there's actually a 0:15:34.240 --> 0:15:37.200 bunch of ants all over the world that are infected 0:15:37.240 --> 0:15:40.680 by this fungus in slightly different ways. So the story 0:15:40.720 --> 0:15:42.400 isn't the same for all of them. The story I 0:15:42.480 --> 0:15:45.120 gave you is a story that I'd initially read for 0:15:45.640 --> 0:15:49.680 Ophagio Cordyceps unilateralis infecting an ant species in the tropics. 0:15:50.160 --> 0:15:52.760 But yeah, there's a lot of this happening in our world, and. 0:15:52.880 --> 0:15:55.560 Within this species of ant and this species of fungus. 0:15:56.000 --> 0:15:58.080 You're saying, there's not a lot of variation in the 0:15:58.160 --> 0:16:00.720 behavior of ants. They like basically all do the same 0:16:01.040 --> 0:16:02.680 march to death and then brain. 0:16:02.480 --> 0:16:04.880 Explosion, brain explosion or you. 0:16:04.880 --> 0:16:06.720 Know, fungal stock extrusion or what. 0:16:06.960 --> 0:16:08.880 Yeah. Yeah, So we are going to talk about how 0:16:08.920 --> 0:16:11.480 they differ a little bit. The details can differ depending 0:16:11.520 --> 0:16:14.320 on where you are, but the story is generally the same. 0:16:14.400 --> 0:16:17.920 That they find a way to be up above the 0:16:18.200 --> 0:16:20.400 areas where the foragers usually go so that they can 0:16:20.520 --> 0:16:21.560 rain the spores back down. 0:16:21.600 --> 0:16:24.200 Again. Wow, amazing, So tell us how it works. 0:16:24.360 --> 0:16:27.520 So first, I want to note we call these zombie ants, 0:16:27.800 --> 0:16:31.000 and I often get people in the field grumpy with 0:16:31.160 --> 0:16:33.240 me for calling them zombies because they're like people are 0:16:33.280 --> 0:16:35.960 gonna think they come back from the dead. Dear listener, 0:16:36.040 --> 0:16:38.280 I don't think that you think that ants come back 0:16:38.320 --> 0:16:41.200 from the dead. But just to be clear, the zombie 0:16:41.240 --> 0:16:44.120 ants do not come back from the dead. They are 0:16:44.200 --> 0:16:46.560 their behavior is getting hijacked while they're alive, and then 0:16:46.600 --> 0:16:49.560 they die in a very particular position that benefits the fungus. 0:16:49.880 --> 0:16:53.480 So you're saying they're not zombies because the ants haven't died. 0:16:53.640 --> 0:16:57.400 They're just in some sort of like controlled state where 0:16:57.400 --> 0:16:59.240 they're not really acting the way they would if they 0:16:59.280 --> 0:17:02.880 were normal ants. They're like drunk or they're hallucinating or something. 0:17:03.000 --> 0:17:05.320 Something like that, and yet it looks like their circadian 0:17:05.400 --> 0:17:07.840 rhythms are getting messed with. So Terarissa de Becker's lab 0:17:08.000 --> 0:17:10.520 has looked at how a big part of the manipulation 0:17:10.680 --> 0:17:13.920 seems to be them doing kind of normal behaviors but 0:17:14.040 --> 0:17:15.360 at abnormal times. 0:17:15.720 --> 0:17:18.159 So that seems to me a very technical definition of zombie. 0:17:18.200 --> 0:17:21.359 I mean, if humans, for example, were infected by something 0:17:21.400 --> 0:17:24.359 which made them stagger around and want to eat brains, 0:17:24.440 --> 0:17:26.680 but weren't technically dead, would you be there being like, 0:17:26.760 --> 0:17:28.560 excuse me, you're not a zombie. 0:17:28.280 --> 0:17:32.919 Sir, No, Because I love fiction in all of its forms, 0:17:32.960 --> 0:17:35.840 and as long as the rules are consistent in the 0:17:35.880 --> 0:17:38.520 world that's created, I don't care. So when I use 0:17:38.520 --> 0:17:41.320 the word zombie, I basically just mean an organism where 0:17:41.960 --> 0:17:44.880 a significant amount of its behaviors seem to be under 0:17:44.880 --> 0:17:48.400 the control of another critter, and those behaviors are good 0:17:48.520 --> 0:17:51.400 for the parasite but usually bad for the host. 0:17:51.720 --> 0:17:54.399 All right, well, let's take a break because I definitely 0:17:54.480 --> 0:17:57.159 need one, and come back and hear all about the 0:17:57.240 --> 0:18:20.840 details of how this fungus controls this an. Okay, we're back, 0:18:20.880 --> 0:18:22.760 and we're talking about the name of a fungus that 0:18:22.840 --> 0:18:27.000 I cannot pronounce but is amazingly adept at manipulating ants. 0:18:27.400 --> 0:18:29.680 This is a really nice like turn of the tables. 0:18:29.760 --> 0:18:32.359 Usually I'm the one who can't pronounce things. We've got 0:18:32.480 --> 0:18:36.920 to do more episodes with like complex latinate names. But okay, 0:18:37.480 --> 0:18:39.200 So one of the first things I think is so 0:18:39.359 --> 0:18:44.479 amazing about this system is that it evades the social 0:18:44.600 --> 0:18:49.240 immune system that ants have. So ants are very genetically 0:18:49.520 --> 0:18:51.560 related to one another, and they work together for this 0:18:51.720 --> 0:18:55.040 common goal of like helping the queen create more offspring 0:18:55.119 --> 0:18:55.639 and stuff like that. 0:18:55.920 --> 0:18:58.560 And they have complex fractional relationships, right, It's not just 0:18:58.680 --> 0:19:01.040 like you have kids that are half you. You're like 0:19:01.480 --> 0:19:03.440 related by a quarter or a sixth or a third 0:19:03.560 --> 0:19:04.760 or something complicated. Right. 0:19:04.880 --> 0:19:07.200 I think it's like three quarters. Like you're way more 0:19:07.240 --> 0:19:09.520 closely related than like, you know, my brother and I 0:19:09.600 --> 0:19:12.879 would be, for example, typical siblings, and so they're like, 0:19:13.000 --> 0:19:16.359 you know, pretty close to you genetically. And so this 0:19:16.560 --> 0:19:19.840 tends to result in what look like ultruistic behaviors. And 0:19:20.080 --> 0:19:22.280 so if one of the ants comes into the colony 0:19:23.040 --> 0:19:26.879 and is clearly infected with something, the nest has a 0:19:27.040 --> 0:19:30.240 like social immune response where other nestmates will be like, oh, 0:19:30.680 --> 0:19:33.400 you can't bring that in here, man, and they will 0:19:33.560 --> 0:19:36.200 in some cases kill that ant and then go put 0:19:36.240 --> 0:19:39.440 it in like a graveyard somewhere far away from the 0:19:39.520 --> 0:19:41.439