1 00:00:02,120 --> 00:00:06,120 Speaker 1: If you're a virus, you have this constant problem. There. 2 00:00:06,160 --> 00:00:09,879 Speaker 1: You are successfully reproducing in some rabbit or some chicken, 3 00:00:10,280 --> 00:00:12,960 Speaker 1: or let's say some person, and then one day the 4 00:00:13,000 --> 00:00:17,480 Speaker 1: person's immune system gets wise starts attacking you, destroying you. 5 00:00:17,480 --> 00:00:19,480 Speaker 1: You need to find a new host, and you need 6 00:00:19,520 --> 00:00:23,240 Speaker 1: to do it fast. Viruses have evolved lots of strategies 7 00:00:23,280 --> 00:00:25,840 Speaker 1: for solving this problem. Some of them fly out of 8 00:00:25,840 --> 00:00:29,920 Speaker 1: people's mouths and noses and sneezes and coughs. Others ooze 9 00:00:29,920 --> 00:00:34,520 Speaker 1: out in bodily fluids like blood and saliva, and some viruses, 10 00:00:34,960 --> 00:00:39,559 Speaker 1: in a truly amazing twist of evolution, have enlisted mosquitoes. 11 00:00:40,560 --> 00:00:43,960 Speaker 1: They're like these missiles that fly through the air, sucking 12 00:00:44,040 --> 00:00:46,720 Speaker 1: virus out of one host and injecting it into another. 13 00:00:47,400 --> 00:00:52,160 Speaker 1: Diseases like Zeka, West Nile, Japanese encephalitis, and yellow fever 14 00:00:52,560 --> 00:00:55,680 Speaker 1: have killed millions of people over the course of human history, 15 00:00:56,080 --> 00:01:00,520 Speaker 1: and they couldn't have done it without mosquitos. I'm Jacob Goldstein, 16 00:01:00,560 --> 00:01:04,080 Speaker 1: and this is Incubation, a show about viruses. Today on 17 00:01:04,120 --> 00:01:07,720 Speaker 1: the show, how mosquitoes learned to love people and how 18 00:01:07,760 --> 00:01:14,199 Speaker 1: those mosquitoes and the viruses they carried changed human history. 19 00:01:24,080 --> 00:01:26,000 Speaker 1: In the second half of today's show, we'll hear the 20 00:01:26,040 --> 00:01:29,679 Speaker 1: story of how mosquitoes carrying yellow fever were enlisted as 21 00:01:29,680 --> 00:01:32,680 Speaker 1: a kind of biological weapon and how they played a 22 00:01:32,760 --> 00:01:36,800 Speaker 1: key role in shaping the history of the Western hemisphere. First, though, 23 00:01:36,920 --> 00:01:40,120 Speaker 1: we're going to talk about how those particular mosquitoes, a 24 00:01:40,160 --> 00:01:43,840 Speaker 1: species called eighties a gypty, came to love humans in 25 00:01:43,880 --> 00:01:46,319 Speaker 1: the first place, and we'll also get a sense of 26 00:01:46,360 --> 00:01:51,200 Speaker 1: what climate change and urbanization mean for the future of humans, mosquitoes, 27 00:01:51,320 --> 00:01:54,520 Speaker 1: and mosquito born viruses. My guest for this part of 28 00:01:54,560 --> 00:01:58,320 Speaker 1: the show is Noah Rose. He's an assistant professor in 29 00:01:58,360 --> 00:02:02,360 Speaker 1: the Department of Ecology, Behavior and Evolution at the University 30 00:02:02,400 --> 00:02:06,920 Speaker 1: of California, San Diego, and he is really really into mosquitoes. 31 00:02:09,280 --> 00:02:12,560 Speaker 1: What's the most mosquito bites you ever had at one time? 32 00:02:13,720 --> 00:02:16,720 Speaker 2: You Know what's kind of funny is in my old job, 33 00:02:16,919 --> 00:02:18,960 Speaker 2: I would feed my own mosquitoes. 34 00:02:20,160 --> 00:02:22,880 Speaker 1: When you say I would feed my own mosquitoes, what 35 00:02:22,960 --> 00:02:23,679 Speaker 1: does that mean? 36 00:02:24,040 --> 00:02:26,120 Speaker 2: Like I would stick my arm in a cage and 37 00:02:26,120 --> 00:02:28,880 Speaker 2: they would bite me, and I always dress. 38 00:02:29,040 --> 00:02:31,760 Speaker 1: You would fed them just like giving food to a dog, 39 00:02:31,880 --> 00:02:33,720 Speaker 1: but instead of putting kimble on a plate. You'd put 40 00:02:33,760 --> 00:02:36,680 Speaker 1: your arm in a box and your arm was not protected, 41 00:02:36,680 --> 00:02:38,280 Speaker 1: they would just come and bite you so that they 42 00:02:38,280 --> 00:02:38,840 Speaker 1: could live. 43 00:02:39,040 --> 00:02:41,040 Speaker 2: That's exactly right. I was like, I'm gonna feed all 44 00:02:41,040 --> 00:02:43,400 Speaker 2: my mosquitoes, and I'm just gonna like, I'm gonna like 45 00:02:43,400 --> 00:02:45,320 Speaker 2: bite the bullet, and I'm gonna like know that I 46 00:02:45,360 --> 00:02:47,360 Speaker 2: can just do this. The buck stops here. I can 47 00:02:47,440 --> 00:02:50,120 Speaker 2: keep my mosquitos alive. And so I like went all in. 48 00:02:50,200 --> 00:02:52,360 Speaker 2: I got I don't know, like tens of thousands of 49 00:02:52,360 --> 00:02:55,120 Speaker 2: bites over a short period of time. And then I 50 00:02:55,160 --> 00:02:58,040 Speaker 2: got to I got to my new job, and they're like, yeah, 51 00:02:58,080 --> 00:03:00,680 Speaker 2: we don't really like let people do that here. We 52 00:03:00,720 --> 00:03:02,280 Speaker 2: think it's gross and maybe bad. 53 00:03:04,160 --> 00:03:07,600 Speaker 1: Fair enough, I guess fair enough. So, okay, if we 54 00:03:07,639 --> 00:03:11,040 Speaker 1: go to the time when you're starting out studying mosquitoes 55 00:03:11,120 --> 00:03:14,200 Speaker 1: as a postdoc, like, what are the big questions you're 56 00:03:14,200 --> 00:03:15,040 Speaker 1: trying to figure out? 57 00:03:15,320 --> 00:03:17,800 Speaker 2: Yeah, so, really, what we were trying to understand is 58 00:03:17,840 --> 00:03:21,799 Speaker 2: what makes mosquitoes particularly good at spreading disease? Because there's 59 00:03:21,800 --> 00:03:24,200 Speaker 2: lots of mosquitoes in the world, and not all of 60 00:03:24,280 --> 00:03:26,680 Speaker 2: them are equally good at spreading disease. Actually, you know, 61 00:03:26,800 --> 00:03:28,880 Speaker 2: of the over three thousand species that are out there, 62 00:03:29,200 --> 00:03:32,200 Speaker 2: the vast majority are not really causing so many problems 63 00:03:32,200 --> 00:03:34,560 Speaker 2: for people, but a few of them are really really 64 00:03:34,600 --> 00:03:37,360 Speaker 2: good at spreading disease. Maybe the best example of that 65 00:03:37,640 --> 00:03:41,080 Speaker 2: is eighties a gypty. Eighties agypty is like an amazing 66 00:03:41,280 --> 00:03:44,680 Speaker 2: vector of viral diseases, in particular diseases like yellow fever, 67 00:03:45,240 --> 00:03:48,240 Speaker 2: dangay zeka, chicken gunya. It's really good at spreading those 68 00:03:48,280 --> 00:03:51,880 Speaker 2: diseases for a lot of reasons. But kind of high 69 00:03:51,920 --> 00:03:54,120 Speaker 2: up on that list of reasons is it loves to 70 00:03:54,160 --> 00:03:56,440 Speaker 2: live around and bite people. And if you want to 71 00:03:56,480 --> 00:03:59,760 Speaker 2: spread disease, you know, from person to person, living around 72 00:03:59,760 --> 00:04:01,880 Speaker 2: people biting people super super helpful. 73 00:04:02,000 --> 00:04:04,280 Speaker 1: So just a sort of threshold question if you're looking 74 00:04:04,280 --> 00:04:07,560 Speaker 1: at any of the thousands of species of mosquitoes, so 75 00:04:07,680 --> 00:04:10,520 Speaker 1: obvious I wouldn't even think of it. Does it bite 76 00:04:10,560 --> 00:04:13,080 Speaker 1: people a lot? Because if it doesn't, then for the 77 00:04:13,080 --> 00:04:15,280 Speaker 1: most part, we're not going to be so worried about it. 78 00:04:15,480 --> 00:04:18,599 Speaker 2: That is exactly right. Most of the species of mosquitoes, 79 00:04:18,640 --> 00:04:21,000 Speaker 2: their life cycle, it just doesn't really involve people. It's 80 00:04:21,040 --> 00:04:23,000 Speaker 2: not about us. It's you know, they're living in the forest, 81 00:04:23,000 --> 00:04:25,120 Speaker 2: they're biting animals. They're breeding in some sort of natural 82 00:04:25,120 --> 00:04:27,400 Speaker 2: standing water. They're just not spreading a ton of disease 83 00:04:27,440 --> 00:04:29,279 Speaker 2: from person to person because they don't survive that well 84 00:04:29,320 --> 00:04:32,360 Speaker 2: in human habitats. But a few mosquitoes are really, really 85 00:04:32,360 --> 00:04:34,360 Speaker 2: good at that, and eighties Egypty is one of the best. 86 00:04:34,880 --> 00:04:37,080 Speaker 2: And so the next question is how did it come 87 00:04:37,080 --> 00:04:39,680 Speaker 2: to be that way? Because this mosquito wasn't always that way. 88 00:04:40,240 --> 00:04:45,080 Speaker 2: It evolved from something, right, It evolved from an ancestral population, 89 00:04:45,760 --> 00:04:48,159 Speaker 2: probably with a life cycle that did not involve living 90 00:04:48,200 --> 00:04:50,360 Speaker 2: in a plastic bucket in near backyard and biting a human. 91 00:04:50,920 --> 00:04:54,520 Speaker 1: And so to answer this question, you traveled to sub 92 00:04:54,560 --> 00:04:58,799 Speaker 1: Saharan Africa right to study eighties agypty. What did you find? 93 00:04:59,080 --> 00:05:03,120 Speaker 2: Yeah, so, basically, most populations of eighties of Gypty in 94 00:05:03,160 --> 00:05:06,560 Speaker 2: its native range of sub Saharan Africa, they don't particularly 95 00:05:06,600 --> 00:05:10,440 Speaker 2: love human hosts. They're willing to bite humans, but they 96 00:05:10,520 --> 00:05:13,840 Speaker 2: actually they would like to bite a wide variety of 97 00:05:13,960 --> 00:05:16,360 Speaker 2: vertebrate hosts, and humans are not their favorite of those. 98 00:05:16,440 --> 00:05:18,599 Speaker 2: Humans are like, yeah, I'll take it if I have to, 99 00:05:18,720 --> 00:05:19,840 Speaker 2: But they don't love how we smell. 100 00:05:19,960 --> 00:05:21,560 Speaker 1: We're an acquired taste. 101 00:05:21,800 --> 00:05:25,200 Speaker 2: We are a very acquired taste exactly. But a few 102 00:05:25,240 --> 00:05:28,480 Speaker 2: populations are really really strongly specialized on human hosts and 103 00:05:28,560 --> 00:05:31,560 Speaker 2: human habitats. They love how we smell. And those are 104 00:05:31,560 --> 00:05:35,320 Speaker 2: populations living in this region called the Sahel. It's just 105 00:05:35,400 --> 00:05:38,479 Speaker 2: south of the Sahara Desert, where for most of the 106 00:05:38,560 --> 00:05:41,800 Speaker 2: year it's really hot, really dry, a terrible place to 107 00:05:41,839 --> 00:05:44,239 Speaker 2: be a mosquito. You know, mosquitoes thrive on standing water, 108 00:05:44,600 --> 00:05:47,400 Speaker 2: but for a couple months it's mosquito paradise. They have heavy, 109 00:05:47,440 --> 00:05:51,200 Speaker 2: heavy rains, pools of water kind of everywhere, but that 110 00:05:51,360 --> 00:05:53,440 Speaker 2: dry season is so hot and so long that it 111 00:05:53,480 --> 00:05:57,240 Speaker 2: seems like the ancestral generalist form of the mosquito it 112 00:05:57,320 --> 00:05:59,560 Speaker 2: just doesn't survive that well. There. Instead, we find these 113 00:05:59,560 --> 00:06:03,360 Speaker 2: populations of eighties of gipty that are really tightly interconnected 114 00:06:03,360 --> 00:06:06,400 Speaker 2: with settled human populations, right, So they're not breeding in 115 00:06:06,440 --> 00:06:09,880 Speaker 2: their normal treeholes or rock pools. They're breeding in things 116 00:06:09,920 --> 00:06:13,039 Speaker 2: like heavy clay vessels used to store water. It's an 117 00:06:13,080 --> 00:06:16,520 Speaker 2: amazing habitat for a human specialist mosquito. And so we 118 00:06:16,600 --> 00:06:19,080 Speaker 2: think that this is actually the original context that sort 119 00:06:19,120 --> 00:06:21,800 Speaker 2: of drove eighties Egypty to specialize on humans. 120 00:06:22,400 --> 00:06:28,080 Speaker 1: You observe this, and you're also doing essentially genomic analysis, right, 121 00:06:28,120 --> 00:06:29,880 Speaker 1: You're trying to figure out kind of the history of 122 00:06:29,920 --> 00:06:33,000 Speaker 1: how this came to be by studying the genetics of 123 00:06:33,080 --> 00:06:36,839 Speaker 1: these different populations, and in particular the subpopulation that is 124 00:06:36,920 --> 00:06:39,760 Speaker 1: like kind of a weird o mosquito, right, this weird 125 00:06:39,760 --> 00:06:44,480 Speaker 1: oh mosquito that happens to love human dwellings, that happens 126 00:06:44,560 --> 00:06:47,719 Speaker 1: to love these clay vessels where people store their water. 127 00:06:47,920 --> 00:06:51,040 Speaker 2: That's exactly right. And so with the genetics, basically the 128 00:06:51,120 --> 00:06:54,320 Speaker 2: question we're asking is like what is the genetic signature 129 00:06:54,360 --> 00:06:56,919 Speaker 2: of this human specialist mosquito? And in particular, what we 130 00:06:57,000 --> 00:07:00,040 Speaker 2: find is that there's a shared genetic basis in the 131 00:07:00,080 --> 00:07:04,360 Speaker 2: Sahelian populations and the invasive populations that came to spread 132 00:07:04,400 --> 00:07:07,000 Speaker 2: all over the whole world. Right, So we think that 133 00:07:07,320 --> 00:07:10,840 Speaker 2: these populations in the Sahel are likely the origin of 134 00:07:11,080 --> 00:07:13,640 Speaker 2: this human specialist form. But they didn't stay there. They 135 00:07:13,760 --> 00:07:17,240 Speaker 2: spread everywhere across the global tropics, at least in urban areas, 136 00:07:18,040 --> 00:07:20,280 Speaker 2: and they became this like total menace. 137 00:07:20,800 --> 00:07:23,880 Speaker 1: Okay, so you are going off to sub Saharan Africa, 138 00:07:24,400 --> 00:07:26,480 Speaker 1: so I get that you want to understand how eighties 139 00:07:26,520 --> 00:07:29,680 Speaker 1: of gypsy evolved to love people and therefore spread disease. 140 00:07:30,000 --> 00:07:32,480 Speaker 1: But what's the sort of smaller set of things you 141 00:07:32,560 --> 00:07:34,400 Speaker 1: have to do to actually figure that out. 142 00:07:34,640 --> 00:07:36,240 Speaker 2: Yeah, so there's a bunch of things, but the two 143 00:07:36,280 --> 00:07:40,520 Speaker 2: main things are studying and quantifying their behavioral preference for humans. 144 00:07:40,560 --> 00:07:43,200 Speaker 2: How much do the mosquitoes want to bite humans? And 145 00:07:43,240 --> 00:07:46,800 Speaker 2: sequencing their genomes. That's the big thing. And the way 146 00:07:46,840 --> 00:07:50,240 Speaker 2: we do that is using a device called a live 147 00:07:50,280 --> 00:07:52,960 Speaker 2: host two port old factometer, which is a lot of 148 00:07:53,120 --> 00:07:56,000 Speaker 2: very fancy words to say, a big plastic box with 149 00:07:56,400 --> 00:07:57,880 Speaker 2: a lot of mosquitos on the inside and has two 150 00:07:57,920 --> 00:07:58,760 Speaker 2: holes in the side. 151 00:07:58,880 --> 00:08:02,560 Speaker 1: Old factometer, like measuring their smell or something. Is that 152 00:08:02,600 --> 00:08:03,080 Speaker 1: what that is? 153 00:08:03,320 --> 00:08:08,480 Speaker 2: Yeah, exactly, it's like measuring their smell. And basically they 154 00:08:08,520 --> 00:08:10,520 Speaker 2: can choose to go in one of two traps. One 155 00:08:10,600 --> 00:08:14,040 Speaker 2: leads to a human arm. One leads to non human animal, 156 00:08:14,280 --> 00:08:16,880 Speaker 2: in many cases a literal guinea pig, because they have 157 00:08:16,960 --> 00:08:19,040 Speaker 2: a nice temperament and they smell good to mosquitos. 158 00:08:19,280 --> 00:08:22,440 Speaker 1: And what's the human arm? You got some undergrad sitting 159 00:08:22,480 --> 00:08:24,560 Speaker 1: there all day for minimum wage or what. 160 00:08:25,520 --> 00:08:26,280 Speaker 2: Usually it's me. 161 00:08:27,760 --> 00:08:31,200 Speaker 1: It's your own arm sitting there to see what the mosquitoes. 162 00:08:30,800 --> 00:08:33,000 Speaker 2: Like, yeah, it doesn't have to be me. And in fact, 163 00:08:33,080 --> 00:08:35,360 Speaker 2: you know, we made sure that we got similar results 164 00:08:35,360 --> 00:08:38,080 Speaker 2: with different people, because it would be awfully embarrassing to 165 00:08:38,240 --> 00:08:40,160 Speaker 2: do a whole study of like what a mosquito's like 166 00:08:40,200 --> 00:08:41,960 Speaker 2: and then have it be like, oh, no, it's just 167 00:08:42,040 --> 00:08:43,600 Speaker 2: like it's just that they like just you. 168 00:08:43,920 --> 00:08:47,400 Speaker 1: Yeah, So, how much time did you spend with your 169 00:08:47,640 --> 00:08:50,200 Speaker 1: arm in the mosquito box? 170 00:08:50,960 --> 00:08:53,280 Speaker 2: I mean, cumulative months of my life? It was it 171 00:08:53,320 --> 00:08:55,840 Speaker 2: was a lot of sitting with my arm in the box. Yeah, 172 00:08:55,880 --> 00:08:57,320 Speaker 2: it was you learn to type with. 173 00:08:57,280 --> 00:09:00,000 Speaker 1: One hand or something. So would you listen to podcast? 174 00:09:00,040 --> 00:09:00,800 Speaker 1: That's what you do? 175 00:09:01,080 --> 00:09:04,640 Speaker 2: I mostly did audiobooks and just kind of zoning out. 176 00:09:04,720 --> 00:09:07,839 Speaker 2: You know, it's it's I'm not gonna say it's meditative, 177 00:09:07,880 --> 00:09:10,400 Speaker 2: but you know, it's it's there's something not so terrible 178 00:09:10,400 --> 00:09:13,160 Speaker 2: about being like, I'm working while you're clearly just sitting 179 00:09:13,200 --> 00:09:14,760 Speaker 2: in a chair. There's worse things in life. 180 00:09:15,160 --> 00:09:17,440 Speaker 1: And are you getting bitten by the mosquitoes? 181 00:09:17,720 --> 00:09:19,400 Speaker 2: Now there's like a piece of screen in the way, 182 00:09:19,480 --> 00:09:23,000 Speaker 2: so they fly towards the arm or the guinea pig 183 00:09:23,200 --> 00:09:25,160 Speaker 2: and they sort of accumulate up against the screen where 184 00:09:25,160 --> 00:09:27,200 Speaker 2: they're like furiously you can see them. It's kind of 185 00:09:27,240 --> 00:09:29,880 Speaker 2: it's kind of horrifying to see. They're like straining against 186 00:09:29,880 --> 00:09:32,120 Speaker 2: the screen, pushing their body up against it and pushing 187 00:09:32,120 --> 00:09:33,439 Speaker 2: their little prebosses through it. 188 00:09:33,480 --> 00:09:35,840 Speaker 1: They want so badly to suck your blood. 189 00:09:36,120 --> 00:09:39,679 Speaker 2: They really really, they're quite motivated, but they can't get 190 00:09:39,720 --> 00:09:40,000 Speaker 2: to it. 191 00:09:41,040 --> 00:09:44,360 Speaker 1: So so you've done this work this, you know, collecting 192 00:09:44,400 --> 00:09:47,760 Speaker 1: the data, studying the sense of smell with your arm 193 00:09:47,760 --> 00:09:50,320 Speaker 1: in the box, doing the genetic analysis, and in the 194 00:09:50,440 --> 00:09:52,960 Speaker 1: end you publish a couple of papers that really kind 195 00:09:52,960 --> 00:09:57,800 Speaker 1: of tell this thousands of years long story of how 196 00:09:57,880 --> 00:10:02,160 Speaker 1: mosquitoes came to you know, bite people and more importantly, 197 00:10:02,200 --> 00:10:06,000 Speaker 1: came to be this really important disease vector. So like, 198 00:10:06,440 --> 00:10:09,160 Speaker 1: tell me that story. Start a long time ago. 199 00:10:10,000 --> 00:10:14,520 Speaker 2: Go back thousands of years ago. There's eighties agypty mosquitos 200 00:10:14,559 --> 00:10:17,000 Speaker 2: living in the forest, breeding in tree holes and rock 201 00:10:17,000 --> 00:10:20,440 Speaker 2: pools and sort of opportunistically biting the first vertebrate hosts 202 00:10:20,480 --> 00:10:22,760 Speaker 2: that they come across. So like, yep, over there, I 203 00:10:22,800 --> 00:10:24,760 Speaker 2: see that little animal, I'm going to bite it great, 204 00:10:24,800 --> 00:10:26,720 Speaker 2: and then they lay their eggs and you know, life 205 00:10:26,720 --> 00:10:29,120 Speaker 2: cycle complete. It's like any one of those other three 206 00:10:29,160 --> 00:10:32,760 Speaker 2: thousand mosquitos that were not that worried about. The Sahara 207 00:10:32,800 --> 00:10:35,840 Speaker 2: Desert between about fifteen thousand to five thousand years ago, 208 00:10:36,080 --> 00:10:38,480 Speaker 2: more or less, was not the desert we know it 209 00:10:38,520 --> 00:10:41,120 Speaker 2: as today. It was sort of a grassland, the green 210 00:10:41,200 --> 00:10:44,400 Speaker 2: Sahara people call it. And during that time, there were 211 00:10:44,440 --> 00:10:47,400 Speaker 2: lots of sort of distributed human societies, like living as 212 00:10:47,480 --> 00:10:50,240 Speaker 2: hunter gatherers. You can find rock carvings in the middle 213 00:10:50,280 --> 00:10:52,920 Speaker 2: of the Sahara Desert in places where you know it's 214 00:10:53,000 --> 00:10:56,480 Speaker 2: totally inhospitable, and they like depict these sort of idyllic 215 00:10:56,520 --> 00:10:59,040 Speaker 2: scenes of like hunting big game on a rolling grassland. 216 00:10:59,080 --> 00:11:02,640 Speaker 2: It's totally and a little bit strange. But what happened 217 00:11:02,679 --> 00:11:05,640 Speaker 2: is that about five thousand years ago the Sahara Desert 218 00:11:05,840 --> 00:11:09,320 Speaker 2: just dried up. That whole area dried up, and that 219 00:11:09,440 --> 00:11:11,280 Speaker 2: changed a lot of things. But one of the most 220 00:11:11,280 --> 00:11:15,280 Speaker 2: important things it did for humans was it drove people 221 00:11:15,320 --> 00:11:19,240 Speaker 2: to kind of settle down and shift to these different 222 00:11:19,240 --> 00:11:21,199 Speaker 2: ways of living. And in this hell you have the 223 00:11:21,240 --> 00:11:24,000 Speaker 2: emergence of settled human societies on the edge of the 224 00:11:24,040 --> 00:11:28,800 Speaker 2: Sahara Desert, storing water, farming things like millet. And when 225 00:11:28,840 --> 00:11:33,280 Speaker 2: all that happens, that modern niche for human specialist mosquitos 226 00:11:33,360 --> 00:11:35,840 Speaker 2: kind of emerged where you have this place that's otherwise 227 00:11:35,960 --> 00:11:39,720 Speaker 2: inhospitable to mosquitoes, but there's an amazing ecological niche living 228 00:11:39,720 --> 00:11:42,480 Speaker 2: with humans. And so it's the drying of the Sahara 229 00:11:42,520 --> 00:11:45,640 Speaker 2: desert and the emergence of that human specialist niche that 230 00:11:45,679 --> 00:11:47,720 Speaker 2: seems to have driven the evolution of the mosquito. 231 00:11:48,120 --> 00:11:52,120 Speaker 1: So you have the humans presumably who were living their 232 00:11:52,160 --> 00:11:55,000 Speaker 1: best life when it was a grassland hunting big game, 233 00:11:55,320 --> 00:11:57,800 Speaker 1: and then it dries up, and the humans are adapting 234 00:11:58,520 --> 00:12:02,959 Speaker 1: to this new environment conditions, you know, storing water, maybe 235 00:12:03,000 --> 00:12:04,720 Speaker 1: farming in a way they didn't before, and kind of 236 00:12:04,800 --> 00:12:09,679 Speaker 1: alongside them, you have the mosquito also adapting to survive. 237 00:12:09,880 --> 00:12:13,079 Speaker 2: Yeah, yeah, exactly. It's a really interesting thing right where 238 00:12:13,120 --> 00:12:15,600 Speaker 2: it's like the way that time works for humans and 239 00:12:15,640 --> 00:12:18,160 Speaker 2: for mosquitoes is very different, right, Like mosquitos get like 240 00:12:18,200 --> 00:12:20,559 Speaker 2: ten to fifteen generations a year a. 241 00:12:20,600 --> 00:12:23,360 Speaker 1: Year, so like a month a mosquito, mosquito lives for 242 00:12:23,400 --> 00:12:23,880 Speaker 1: like a month. 243 00:12:24,160 --> 00:12:26,160 Speaker 2: They live for like a month exactly. And you know, 244 00:12:26,240 --> 00:12:28,440 Speaker 2: the average generation time of a human is like twenty 245 00:12:28,520 --> 00:12:32,280 Speaker 2: nine thirty years roughly, and so you know, for every 246 00:12:32,360 --> 00:12:35,239 Speaker 2: human generation, you get about four hundred mosquito generations. 247 00:12:35,440 --> 00:12:37,880 Speaker 1: H huh. So that's just that much more evolution, that 248 00:12:37,960 --> 00:12:40,400 Speaker 1: much more genetic iteration exactly. 249 00:12:40,440 --> 00:12:42,680 Speaker 2: So it's like the last ten thousand years of human 250 00:12:43,200 --> 00:12:47,000 Speaker 2: history and cultural change is like, you know, equivalent for 251 00:12:47,080 --> 00:12:50,200 Speaker 2: the mosquitoes to like the last four million years of 252 00:12:50,280 --> 00:12:52,760 Speaker 2: human evolution. And when you think about like four million 253 00:12:52,840 --> 00:12:55,240 Speaker 2: years of human evolution, it's like all the fun stuff, right, 254 00:12:55,280 --> 00:12:58,480 Speaker 2: it's like everything that we care about. And so for 255 00:12:58,559 --> 00:13:02,280 Speaker 2: these mosquitoes, all of their most interesting, like really interesting 256 00:13:02,280 --> 00:13:05,959 Speaker 2: evolutionary changes they're taking place like over the time scale 257 00:13:06,000 --> 00:13:08,520 Speaker 2: of human history, right, And so it's this really cool 258 00:13:08,559 --> 00:13:12,600 Speaker 2: thing where we can simultaneously study how humans are sort 259 00:13:12,600 --> 00:13:14,920 Speaker 2: of shaping the planet, how humans are changing the planet, 260 00:13:15,160 --> 00:13:16,840 Speaker 2: and how that's changing mosquitoes. 261 00:13:17,600 --> 00:13:21,240 Speaker 1: So we've been talking about the past, right, and your 262 00:13:21,280 --> 00:13:24,800 Speaker 1: insights into how eighties egypty came to be this very 263 00:13:24,880 --> 00:13:28,920 Speaker 1: important disease vector in the world. What does your work 264 00:13:28,960 --> 00:13:30,280 Speaker 1: tell us about the future. 265 00:13:30,600 --> 00:13:32,439 Speaker 2: Yeah, well, I mean this is a topic I'm really 266 00:13:32,480 --> 00:13:36,160 Speaker 2: interested in, in particular because the story of eighties egypty 267 00:13:36,200 --> 00:13:39,000 Speaker 2: it's not over. It's still playing out, right, we still 268 00:13:39,000 --> 00:13:42,000 Speaker 2: have populations of eighties agypty that are not the amazing vector. 269 00:13:42,080 --> 00:13:44,840 Speaker 2: In most of the native range, eighties e gypty is 270 00:13:44,880 --> 00:13:48,320 Speaker 2: the generalist form, but that seems to be changing a 271 00:13:48,320 --> 00:13:50,800 Speaker 2: lot of the fastest growing cities in the world. They're 272 00:13:51,120 --> 00:13:55,240 Speaker 2: in sub Saharan Africa. There's places like Waga Doogu and Brikina, Faso, 273 00:13:55,400 --> 00:13:59,440 Speaker 2: Kumasi and Ghana. And in those cities the mosquitos seem 274 00:13:59,520 --> 00:14:03,400 Speaker 2: to be evolving a greater specialization on human hosts and habitats. 275 00:14:03,840 --> 00:14:07,720 Speaker 1: Is this a future where disease transmission mosquito by mosquitos 276 00:14:07,800 --> 00:14:11,240 Speaker 1: is going to get worse just because there's more density, 277 00:14:11,280 --> 00:14:13,200 Speaker 1: more urbanization. Is that the story you're telling. 278 00:14:13,840 --> 00:14:16,160 Speaker 2: I think there's good reasonably that that might be playing out, 279 00:14:16,480 --> 00:14:18,199 Speaker 2: not just in the future, but even in the present day. 280 00:14:18,240 --> 00:14:22,440 Speaker 2: For example, Wagga Doogo, Historically speaking, it was not thought 281 00:14:22,520 --> 00:14:26,080 Speaker 2: to be a majorly problematic area for things like dangay fever, 282 00:14:26,520 --> 00:14:28,960 Speaker 2: and in the last couple of years there have been 283 00:14:29,000 --> 00:14:31,960 Speaker 2: these massive outbreaks of dang gay fever and waggadogo. And 284 00:14:32,720 --> 00:14:35,440 Speaker 2: at the same time we can see in the genomes 285 00:14:35,480 --> 00:14:38,960 Speaker 2: of the mosquitoes there that they're becoming more specialized on humans, 286 00:14:38,960 --> 00:14:41,800 Speaker 2: they have more ancestry from that human specialist kind of 287 00:14:41,880 --> 00:14:45,960 Speaker 2: gene pool. Right, the mosquitoes are changing like on contemporary 288 00:14:46,000 --> 00:14:49,720 Speaker 2: time scales, Like the mosquitoes twenty years ago are different 289 00:14:49,720 --> 00:14:52,080 Speaker 2: from the mosquitoes of today are different from the mosquitoes 290 00:14:52,120 --> 00:14:55,080 Speaker 2: of twenty years from now. So it's not just like 291 00:14:55,160 --> 00:14:57,680 Speaker 2: a hypothetical future thing. I think it's like a present 292 00:14:57,800 --> 00:14:58,560 Speaker 2: day dynamic. 293 00:14:59,200 --> 00:15:03,680 Speaker 1: So the initial wave of specialization thousands of years ago 294 00:15:03,760 --> 00:15:07,120 Speaker 1: was triggered by environmental change, right by the drying out 295 00:15:07,160 --> 00:15:11,400 Speaker 1: of the Sahara. In the modern context, is climate change 296 00:15:11,440 --> 00:15:13,360 Speaker 1: relevant to this discussion. 297 00:15:13,080 --> 00:15:14,840 Speaker 2: Yeah, that's a great question. It's one that I get 298 00:15:14,880 --> 00:15:16,600 Speaker 2: all the time, and it's one that I'm very interested 299 00:15:16,600 --> 00:15:20,960 Speaker 2: in understanding. It's hard to say for sure, because climate 300 00:15:21,000 --> 00:15:25,880 Speaker 2: has really complex effects on mosquito born disease transmission. When 301 00:15:25,920 --> 00:15:28,360 Speaker 2: it comes to some of the topics I've studied, Like 302 00:15:28,480 --> 00:15:30,240 Speaker 2: so much of what we know about what seems to 303 00:15:30,280 --> 00:15:32,800 Speaker 2: drive mosquitoes to specialize on humans, it's things like either 304 00:15:33,320 --> 00:15:38,160 Speaker 2: urbanization or precipitation variation, but maybe not mean temperature per se. 305 00:15:38,600 --> 00:15:42,440 Speaker 2: But there's indirect ways that I still think climate change 306 00:15:42,520 --> 00:15:45,360 Speaker 2: might contribute to this. For example, climate change can very 307 00:15:45,360 --> 00:15:49,880 Speaker 2: directly contribute to things like people moving very quickly into 308 00:15:49,920 --> 00:15:53,800 Speaker 2: sort of informal settlements in rapidly growing urban areas, because 309 00:15:54,560 --> 00:15:57,280 Speaker 2: it's just like the old way that people were living 310 00:15:57,320 --> 00:15:58,200 Speaker 2: isn't working anymore. 311 00:15:58,280 --> 00:16:00,920 Speaker 1: Right, So it seems like from what you're saying, urbanization 312 00:16:01,120 --> 00:16:05,640 Speaker 1: is a much clearer driver than climate change of basically 313 00:16:06,360 --> 00:16:09,800 Speaker 1: more mosquitoes and more mosquito spread disease. 314 00:16:10,120 --> 00:16:13,680 Speaker 2: That's exactly right. Urbanization is so fast and so extreme 315 00:16:13,840 --> 00:16:17,280 Speaker 2: and represents such a major change to the sort of 316 00:16:17,440 --> 00:16:19,480 Speaker 2: ecosystem that these mosquitoes are living in. 317 00:16:19,680 --> 00:16:24,160 Speaker 1: From like the mosquito pov urbanization domini, Yeah, exact. 318 00:16:24,560 --> 00:16:26,480 Speaker 2: Yeah, if you're a mosquito sitting in a forest and 319 00:16:26,520 --> 00:16:29,640 Speaker 2: the forest gets chopped down and replaced with a giant metropolis, 320 00:16:29,840 --> 00:16:33,560 Speaker 2: that's a bigger change than an environmental change playing out 321 00:16:33,600 --> 00:16:35,160 Speaker 2: more subtly over longer time scales. 322 00:16:35,480 --> 00:16:36,200 Speaker 3: Yeah. 323 00:16:36,520 --> 00:16:41,560 Speaker 4: So if you zoom out and think about what you knew, 324 00:16:42,120 --> 00:16:45,000 Speaker 4: what your worldview was when you started studying mosquitoes, and 325 00:16:45,040 --> 00:16:47,160 Speaker 4: what you know, and kind of the way you think 326 00:16:47,160 --> 00:16:48,119 Speaker 4: about the world. 327 00:16:47,880 --> 00:16:50,840 Speaker 1: Now, how do you think about the world differently. 328 00:16:51,840 --> 00:16:55,440 Speaker 2: I mean, it's an interesting question because you know, the 329 00:16:55,520 --> 00:16:57,640 Speaker 2: thing that got me interested in mosquitos was trying to 330 00:16:57,720 --> 00:17:02,840 Speaker 2: understand how human are affecting our planet, right, like trying 331 00:17:02,840 --> 00:17:07,200 Speaker 2: to understand how we're affecting the environment, how we're reshaping ecosystems. 332 00:17:07,800 --> 00:17:11,679 Speaker 2: And you know, in those days, my main motivation was 333 00:17:11,760 --> 00:17:15,760 Speaker 2: wanting to protect the biodiversity, wanting to protect ecosystems, which 334 00:17:15,800 --> 00:17:18,320 Speaker 2: I still care a lot about. One thing that changes 335 00:17:18,520 --> 00:17:21,680 Speaker 2: just you know, like I sort of realized not everything 336 00:17:21,920 --> 00:17:24,720 Speaker 2: is like about us either like helping or heard things like, 337 00:17:25,200 --> 00:17:28,719 Speaker 2: you know, mosquitos are evolving really quickly to exploit us, 338 00:17:28,720 --> 00:17:32,440 Speaker 2: to make us sick. It's kind of amazing to me 339 00:17:32,600 --> 00:17:36,920 Speaker 2: that mosquitos could do something like evolved to be better 340 00:17:36,960 --> 00:17:39,040 Speaker 2: at taking advantage of us on the same kind of 341 00:17:39,080 --> 00:17:42,720 Speaker 2: timescale that we're talking about, like oh, we're degrading ecosystems, 342 00:17:42,800 --> 00:17:46,920 Speaker 2: or we're removing habitat for charismatic megafauna that we care 343 00:17:46,960 --> 00:17:51,359 Speaker 2: about or things like that, like nature. Also nature is responding. 344 00:17:51,240 --> 00:17:53,320 Speaker 1: So it's like it's like before it was like, oh, 345 00:17:53,480 --> 00:17:56,639 Speaker 1: nature is a victim, and now it's like, yo, mosquitoes 346 00:17:56,680 --> 00:17:58,320 Speaker 1: are kind of kicking ass. 347 00:17:58,800 --> 00:18:01,399 Speaker 2: Yeah, they're really really good at what they do, and like, 348 00:18:01,600 --> 00:18:05,200 Speaker 2: you know, we change the whole way that the place 349 00:18:05,240 --> 00:18:07,160 Speaker 2: they live looks, and they're like, I can do this too. 350 00:18:07,320 --> 00:18:09,359 Speaker 2: I can totally live here, and I can totally bite 351 00:18:09,359 --> 00:18:12,000 Speaker 2: the organisms that live here. They make it work. 352 00:18:14,760 --> 00:18:17,360 Speaker 1: Thanks to my guest Noah Rose, now as an assistant 353 00:18:17,400 --> 00:18:21,040 Speaker 1: professor in the Department of Ecology, Behavior and Evolution at 354 00:18:21,040 --> 00:18:24,919 Speaker 1: the University of California at San Diego. After the break, 355 00:18:25,320 --> 00:18:41,280 Speaker 1: mosquitoes become a biological weapon. Eighties of gypty first came 356 00:18:41,320 --> 00:18:44,840 Speaker 1: to the New World on European slave ships, and along 357 00:18:44,880 --> 00:18:47,679 Speaker 1: with the mosquito came a new disease, a disease that 358 00:18:47,800 --> 00:18:52,280 Speaker 1: until that point had not existed in the Americas, yellow fever. 359 00:18:53,320 --> 00:18:56,600 Speaker 1: John McNeil is a professor of history at Georgetown and 360 00:18:56,640 --> 00:19:00,400 Speaker 1: the author of a book called Mosquito Empires. In the book, 361 00:19:00,480 --> 00:19:03,800 Speaker 1: John makes the case that yellow fever and the mosquitoes 362 00:19:03,840 --> 00:19:07,000 Speaker 1: that transmitted it had a profound effect on the fight 363 00:19:07,080 --> 00:19:11,719 Speaker 1: among European powers to control the Western Hemisphere. Tell me 364 00:19:11,760 --> 00:19:15,320 Speaker 1: about yellow fever historically, going back a couple hundred years, 365 00:19:15,359 --> 00:19:18,240 Speaker 1: so in the seventeen hundreds. What happens in the absence 366 00:19:18,280 --> 00:19:20,800 Speaker 1: of modern medicine if you get yellow fever. 367 00:19:21,280 --> 00:19:25,120 Speaker 5: That all depends on where you were born and raised, 368 00:19:25,400 --> 00:19:30,080 Speaker 5: and what age you are. Children often show no symptoms, 369 00:19:30,320 --> 00:19:33,399 Speaker 5: don't know that they're sick, survive it, and in the 370 00:19:33,400 --> 00:19:39,239 Speaker 5: process acquire lifelong immunity. The worst thing to be is 371 00:19:39,359 --> 00:19:43,200 Speaker 5: in the prime of your life and encountering yellow fever 372 00:19:43,320 --> 00:19:44,119 Speaker 5: for the first time. 373 00:19:44,880 --> 00:19:47,639 Speaker 1: This is going to be very important for our story today. 374 00:19:48,400 --> 00:19:51,320 Speaker 1: What happens if you were in the prime of your 375 00:19:51,359 --> 00:19:53,480 Speaker 1: life and you get yellow fever and you have never 376 00:19:53,520 --> 00:19:54,199 Speaker 1: had it before. 377 00:19:54,680 --> 00:20:00,439 Speaker 5: Odds are you get a high fever and jaundice, that 378 00:20:00,600 --> 00:20:03,399 Speaker 5: is a sure white person in your skin begins to 379 00:20:03,440 --> 00:20:09,359 Speaker 5: turn yellow, and after several days, either you get better 380 00:20:09,560 --> 00:20:13,600 Speaker 5: you're among the lucky ones and immune for life, or 381 00:20:14,080 --> 00:20:18,399 Speaker 5: after a brief respite, you get sicker and you begin 382 00:20:18,560 --> 00:20:25,399 Speaker 5: to vomit up partially coagulated blood with the consistency and 383 00:20:25,520 --> 00:20:31,160 Speaker 5: coloring of coffee grounds. And when that happens, not only 384 00:20:31,200 --> 00:20:34,000 Speaker 5: are your day's numbered, your hours are numbered. 385 00:20:34,680 --> 00:20:38,040 Speaker 1: So there's this one particular moment that you talk about 386 00:20:38,040 --> 00:20:41,200 Speaker 1: in the book where yellow fever plays a central role 387 00:20:41,400 --> 00:20:46,840 Speaker 1: in world history, and that moment is the Battle of Cartagena, 388 00:20:47,480 --> 00:20:50,439 Speaker 1: which took place in modern day Columbia. It happened in 389 00:20:50,520 --> 00:20:53,800 Speaker 1: seventeen forty one. And at this point, right, the Spanish 390 00:20:53,880 --> 00:20:57,320 Speaker 1: control a lot of South America, the British control a 391 00:20:57,359 --> 00:21:01,680 Speaker 1: lot of North America. And then this battle happens when 392 00:21:01,680 --> 00:21:06,800 Speaker 1: the British launched this huge attack against the Spanish in Cartagena. 393 00:21:07,119 --> 00:21:09,520 Speaker 1: So tell me about the battle. Why was this battle 394 00:21:09,560 --> 00:21:10,200 Speaker 1: so important? 395 00:21:10,760 --> 00:21:15,439 Speaker 5: Cartagena was one of the two or three lynchpins of 396 00:21:15,600 --> 00:21:21,760 Speaker 5: Spanish colonial defense. It was also central to the trading 397 00:21:21,840 --> 00:21:28,520 Speaker 5: system of Spanish America, and that included the annual exports 398 00:21:28,560 --> 00:21:33,639 Speaker 5: of silver from mines in the Andes. Everybody who wanted 399 00:21:33,680 --> 00:21:37,040 Speaker 5: to take Spanish America away from the Spanish, what they 400 00:21:37,080 --> 00:21:38,840 Speaker 5: most wanted was silver. 401 00:21:39,720 --> 00:21:43,760 Speaker 1: So was the notion that if a Britain conquered Cartagena, 402 00:21:43,840 --> 00:21:47,800 Speaker 1: they could, like you know, to some degree, conquer the 403 00:21:47,840 --> 00:21:52,160 Speaker 1: Spanish in South America, make Spanish colonies British colonies. 404 00:21:52,440 --> 00:21:55,679 Speaker 5: Yes, that would be the first step. So back in 405 00:21:55,760 --> 00:22:00,720 Speaker 5: London they sent huge reinforcements. They had a twenty nine 406 00:22:00,800 --> 00:22:05,719 Speaker 5: thousand men between soldiers and sailors, and that was probably 407 00:22:06,440 --> 00:22:11,679 Speaker 5: the largest amphibious military expedition in world history up to 408 00:22:12,240 --> 00:22:12,919 Speaker 5: that time. 409 00:22:13,400 --> 00:22:17,000 Speaker 1: So the British are bringing twenty nine thousand men How 410 00:22:17,040 --> 00:22:19,359 Speaker 1: many men do the Spanish have to defend Cartagena? 411 00:22:19,760 --> 00:22:24,280 Speaker 5: Approximately four thousand, seven hundred, so they're out manned what 412 00:22:25,400 --> 00:22:27,440 Speaker 5: six six to one approximately? 413 00:22:27,560 --> 00:22:31,280 Speaker 1: Yes? What are Spain's defenses like in Cartagena? 414 00:22:31,680 --> 00:22:37,400 Speaker 5: The most important thing they had was massive stone fortifications, okay, 415 00:22:37,680 --> 00:22:41,280 Speaker 5: and the significance of that, which the Spaniards well understood 416 00:22:41,600 --> 00:22:46,879 Speaker 5: by seventeen forty, was that the massive fortifications would require 417 00:22:47,080 --> 00:22:50,719 Speaker 5: any attacking force to lay siege to the city, to 418 00:22:50,840 --> 00:22:56,000 Speaker 5: try to bring artillery within range, bash down the walls, 419 00:22:56,600 --> 00:22:59,920 Speaker 5: permit an assault, and that would take weeks. 420 00:23:01,359 --> 00:23:04,959 Speaker 1: So the fortifications wouldn't necessarily prevent an attack, but they 421 00:23:04,960 --> 00:23:09,040 Speaker 1: would slow it down. Why is that important? Why is 422 00:23:09,080 --> 00:23:11,760 Speaker 1: it important that it would take weeks for the British 423 00:23:11,800 --> 00:23:13,280 Speaker 1: to get through the fortifications. 424 00:23:13,680 --> 00:23:17,240 Speaker 5: It's of central importance. The reason is because in the 425 00:23:17,280 --> 00:23:21,560 Speaker 5: course of those weeks, the attacking force would be bitten 426 00:23:21,600 --> 00:23:25,480 Speaker 5: by the local mosquitoes, would acquire the yellow fever virus, 427 00:23:26,000 --> 00:23:29,359 Speaker 5: and the men in question young men in the prime 428 00:23:29,400 --> 00:23:33,080 Speaker 5: of their lives. Born and raised in places such as 429 00:23:33,160 --> 00:23:36,040 Speaker 5: the British Isles. These were people who had no prior 430 00:23:36,119 --> 00:23:42,080 Speaker 5: experience of yellow fever, so they are maximally susceptible and 431 00:23:42,520 --> 00:23:47,000 Speaker 5: within six weeks. The Spanish tended to think the climate, 432 00:23:47,440 --> 00:23:51,880 Speaker 5: which really means yellow fever, would wreak havoc upon the 433 00:23:51,960 --> 00:23:57,120 Speaker 5: attackers and force them to call off their siege. 434 00:23:57,359 --> 00:24:01,520 Speaker 1: So the Spanish are using this, this virus yellow fever 435 00:24:02,080 --> 00:24:06,480 Speaker 1: as like a core part of their military strategy, because 436 00:24:06,480 --> 00:24:09,760 Speaker 1: they know that their own forces are made up of 437 00:24:09,800 --> 00:24:12,600 Speaker 1: people who have immunity. Right, they've grown up locally, they've 438 00:24:12,600 --> 00:24:16,159 Speaker 1: had the disease, whereas that is not true for the attackers. 439 00:24:16,200 --> 00:24:17,320 Speaker 1: For the British. 440 00:24:17,440 --> 00:24:23,159 Speaker 5: Correct they didn't understand yellow fever's mode of transmission, but 441 00:24:23,680 --> 00:24:29,440 Speaker 5: they knew it was extremely deadly to people are fresh 442 00:24:29,880 --> 00:24:31,480 Speaker 5: off the boat from Europe. 443 00:24:32,280 --> 00:24:37,520 Speaker 1: It's almost like a kind of early form of biological warfare. 444 00:24:37,920 --> 00:24:41,119 Speaker 5: Yes, in effect, it was biological warfare. 445 00:24:41,680 --> 00:24:48,240 Speaker 1: Okay, so this is the Spaniard's idea. The British arrive 446 00:24:48,520 --> 00:24:52,119 Speaker 1: with their dozens of ships and their tens of thousands 447 00:24:52,119 --> 00:24:54,040 Speaker 1: of men. What happens? 448 00:24:54,720 --> 00:24:59,920 Speaker 5: So the British prosecuted a siege, tried to move man 449 00:25:00,880 --> 00:25:06,200 Speaker 5: and artillery across the difficult and damp terrain close by 450 00:25:06,400 --> 00:25:10,760 Speaker 5: to Cartagena. Progress was slow. People started to get sick 451 00:25:10,920 --> 00:25:14,440 Speaker 5: within days of disembarking from their ships. 452 00:25:14,920 --> 00:25:18,880 Speaker 1: You mentioned that the British soldiers who had landed at 453 00:25:18,920 --> 00:25:23,120 Speaker 1: Cartagena and were laying siege to the city didn't have tents, 454 00:25:23,880 --> 00:25:26,520 Speaker 1: so they were just lying on the ground, getting bit 455 00:25:26,600 --> 00:25:30,560 Speaker 1: by mosquitoes and getting yellow fever. Yes, why what happened? 456 00:25:30,720 --> 00:25:33,080 Speaker 1: Why didn't they have tents? Like tents had been invented? 457 00:25:33,520 --> 00:25:36,440 Speaker 5: Tents had been invented. There are two things to bear 458 00:25:36,480 --> 00:25:43,320 Speaker 5: in mind here. One is the difficulty of outfitting a gigantic, 459 00:25:43,520 --> 00:25:48,679 Speaker 5: amphibious military expedition on schedule in the eighteenth century is 460 00:25:48,760 --> 00:25:52,080 Speaker 5: not all that easy in the twenty first century. Second 461 00:25:52,119 --> 00:25:56,480 Speaker 5: one is that nobody knew how yellow fever was transmitted. 462 00:25:56,880 --> 00:26:02,479 Speaker 5: Being bitten by mosquitoes did not automatically seem to anyone 463 00:26:02,520 --> 00:26:05,480 Speaker 5: at the time to carry any particular risk. 464 00:26:06,000 --> 00:26:08,199 Speaker 1: A right, like they just thought it was like my 465 00:26:08,320 --> 00:26:11,840 Speaker 1: asthma or something. So what ends up happening in the battle? 466 00:26:11,920 --> 00:26:12,560 Speaker 1: How does it end? 467 00:26:13,359 --> 00:26:19,040 Speaker 5: The admiral got frustrated with the army commander with slow progress, 468 00:26:19,440 --> 00:26:23,000 Speaker 5: and before long they were losing hundreds of men daily 469 00:26:23,720 --> 00:26:30,040 Speaker 5: to yellow fever, and after thirty three days and a 470 00:26:30,240 --> 00:26:36,760 Speaker 5: premature attempt to storm the fortifications, the British withdrew and 471 00:26:36,840 --> 00:26:42,119 Speaker 5: the Spanish defenders were triumphant. They became great heroes in 472 00:26:42,320 --> 00:26:48,879 Speaker 5: Spanish military history. But what they did was not lose 473 00:26:49,400 --> 00:26:53,040 Speaker 5: before yellow fever forced their enemies to withdraw. 474 00:26:53,600 --> 00:26:58,440 Speaker 1: Yeah, it's like the virus with the real conqueror. For Spain, the. 475 00:26:58,440 --> 00:27:04,119 Speaker 5: Virus killed probably twenty men for every one killed in 476 00:27:04,200 --> 00:27:06,960 Speaker 5: combat in this particular encounter. 477 00:27:07,440 --> 00:27:12,680 Speaker 1: Wow. And then you say that the same dynamic plays 478 00:27:12,720 --> 00:27:16,640 Speaker 1: out once the fighting in the Caribbean and South America 479 00:27:16,880 --> 00:27:21,560 Speaker 1: shifts from being one colonial power against another two being 480 00:27:22,320 --> 00:27:23,480 Speaker 1: wars of independence. 481 00:27:24,040 --> 00:27:29,160 Speaker 5: Yes, and the large scale wars for independence in the 482 00:27:29,280 --> 00:27:36,000 Speaker 5: Caribbean really begin with the Haitian Revolution in seventeen ninety one, 483 00:27:36,080 --> 00:27:40,320 Speaker 5: and there British forces and then French forces tried to 484 00:27:40,440 --> 00:27:46,879 Speaker 5: prevent a slave uprising, and those British and French forces 485 00:27:47,359 --> 00:27:53,040 Speaker 5: suffered extreme disease mortality, and they both went after the 486 00:27:53,080 --> 00:27:58,600 Speaker 5: other gave up and Haiti won its independence. I think 487 00:27:58,640 --> 00:28:02,760 Speaker 5: it is in some ways analogous to the way that 488 00:28:03,640 --> 00:28:09,240 Speaker 5: Spanish colonial authorities used their understanding of the disease climate 489 00:28:09,640 --> 00:28:13,639 Speaker 5: to military advantage in places like Cartagena. And the reason 490 00:28:13,680 --> 00:28:17,080 Speaker 5: for that is their own armies were composed of men 491 00:28:17,119 --> 00:28:23,040 Speaker 5: who had either grown up in the Caribbean amid yellow fear, malaria, denge, 492 00:28:23,040 --> 00:28:27,000 Speaker 5: and other infections, or had grown up in Africa and 493 00:28:27,200 --> 00:28:32,399 Speaker 5: similarly had encountered these diseases and were either immune or resistant, 494 00:28:32,920 --> 00:28:37,320 Speaker 5: Whereas the forces sent out to quell the Haitian Revolution 495 00:28:37,960 --> 00:28:43,960 Speaker 5: were recruited from the British Isles, North America, France, in short, 496 00:28:44,200 --> 00:28:48,760 Speaker 5: people who had virtually no immunity or resistance against yellow 497 00:28:48,840 --> 00:28:50,120 Speaker 5: fever and malaria. 498 00:28:50,960 --> 00:28:58,360 Speaker 1: How should this story about yellow fever and colonial warfare 499 00:28:58,440 --> 00:29:02,040 Speaker 1: in the Caribbean, How should that change the way I 500 00:29:02,080 --> 00:29:03,240 Speaker 1: think about history? 501 00:29:04,240 --> 00:29:10,160 Speaker 5: We should understand that until the twentieth century, the great 502 00:29:10,200 --> 00:29:15,480 Speaker 5: majority of death and dying in military campaigns was not 503 00:29:15,520 --> 00:29:20,320 Speaker 5: a result of combat. It was a result of various diseases. 504 00:29:21,000 --> 00:29:24,560 Speaker 5: And there were certain times in places, including the Caribbean 505 00:29:24,600 --> 00:29:28,320 Speaker 5: and the seventeenth, eighteenth, and nineteenth century, in which those 506 00:29:28,360 --> 00:29:33,440 Speaker 5: diseases were you could say partisan, that is, they systematically 507 00:29:33,480 --> 00:29:38,360 Speaker 5: favored one side over another and powerfully influenced the results. 508 00:29:38,640 --> 00:29:41,520 Speaker 1: So it wasn't until the twentieth century, after thousands of 509 00:29:41,600 --> 00:29:45,440 Speaker 1: years of war, that most people who died in war 510 00:29:45,680 --> 00:29:50,560 Speaker 1: died from injuries inflicted by the enemy rather than died 511 00:29:50,600 --> 00:29:52,520 Speaker 1: from infectious disease. 512 00:29:52,880 --> 00:29:58,200 Speaker 5: Yes, and that entails a gigantic and brutal irony. The 513 00:29:58,480 --> 00:30:03,560 Speaker 5: mass slaughter for which the First World War is justifiably 514 00:30:03,760 --> 00:30:10,400 Speaker 5: famous was possible only because military medicine had become sufficiently 515 00:30:10,440 --> 00:30:14,280 Speaker 5: effective that large armies of millions of men could be 516 00:30:14,400 --> 00:30:19,800 Speaker 5: kept alive long enough to butcher one another. Prior to that, 517 00:30:19,920 --> 00:30:25,880 Speaker 5: it was impossible to maintain gigantic armies for any length 518 00:30:25,920 --> 00:30:27,680 Speaker 5: of time because they would get too sick. 519 00:30:28,320 --> 00:30:28,840 Speaker 2: But by the. 520 00:30:28,800 --> 00:30:34,560 Speaker 5: Twentieth century that constraint was relaxed, and mass armies could 521 00:30:34,680 --> 00:30:38,880 Speaker 5: last long enough to kill one another. That's a horrible irony. 522 00:30:40,120 --> 00:30:45,440 Speaker 3: So if we think about this history we've been talking about, 523 00:30:46,240 --> 00:30:49,840 Speaker 3: and then we think about the modern world, where obviously 524 00:30:49,880 --> 00:30:53,480 Speaker 3: we have lots more treatments, medicine is just better now 525 00:30:53,520 --> 00:30:57,200 Speaker 3: than it was then, what lessons does this story hold 526 00:30:57,320 --> 00:31:00,000 Speaker 3: for the dynamics of the modern nace? 527 00:31:00,520 --> 00:31:02,200 Speaker 1: What does it teach us about the way the world 528 00:31:02,200 --> 00:31:03,680 Speaker 1: works today? 529 00:31:03,760 --> 00:31:09,160 Speaker 5: It should help us recognize the fragility of what we 530 00:31:09,280 --> 00:31:14,000 Speaker 5: might consider the Golden Age of health, an era ushered 531 00:31:14,080 --> 00:31:20,840 Speaker 5: in by public health systems, by urban sanitation, by vaccination 532 00:31:21,000 --> 00:31:26,640 Speaker 5: regimes which protect a significant proportion of the entire human 533 00:31:26,720 --> 00:31:31,960 Speaker 5: population from the ravages of infectious disease, and that is 534 00:31:32,000 --> 00:31:36,000 Speaker 5: a comparatively new phenomenon and it is not to be 535 00:31:36,080 --> 00:31:37,000 Speaker 5: taken for granted. 536 00:31:38,040 --> 00:31:39,920 Speaker 1: Thank you so much for your time. It was great 537 00:31:39,920 --> 00:31:40,960 Speaker 1: to talk with you, Jacob. 538 00:31:41,000 --> 00:31:44,240 Speaker 5: Thank you very much. Thanks for inviting me on the show. 539 00:31:49,120 --> 00:31:52,320 Speaker 1: John McNeil's a professor of history at Georgetown and author 540 00:31:52,360 --> 00:31:55,960 Speaker 1: of the book Mosquito Empires. Thanks to both my guests today, 541 00:31:56,200 --> 00:31:59,520 Speaker 1: Noah Rose and John McNeil. Next week on the show, 542 00:32:00,200 --> 00:32:04,640 Speaker 1: Ken Measle's Cure Cancer, A very weird good thing was 543 00:32:04,680 --> 00:32:10,280 Speaker 1: going on. Incubation is a co production of Pushkin Industries 544 00:32:10,320 --> 00:32:14,200 Speaker 1: and Ruby Studio at iHeartMedia. It's produced by Kate Ferby 545 00:32:14,280 --> 00:32:17,600 Speaker 1: and Brittany Cronin. The show is edited by Lacey Roberts. 546 00:32:17,760 --> 00:32:22,120 Speaker 1: It's mastered by Sarah Bruguire, fact checking by Joseph friedman Or. 547 00:32:22,160 --> 00:32:26,200 Speaker 1: Executive producers are Lacy Roberts and Matt Romono. I'm Jacob Goldstein. 548 00:32:26,400 --> 00:32:27,200 Speaker 1: Thanks for listening.