Learn about how patient O became patient zero, what it takes for a species to evolve twice, and how pesky fruit flies keep getting into your garbage.
Learn about how patient O became patient zero, what it takes for a species to evolve twice, and how pesky fruit flies keep getting into your garbage.
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It's "Patient O," Not "Patient Zero" by Ashley Hamer
With Iterative Evolution, a Species Can Evolve TWICE by Cameron Duke
How do fruitflies keep getting into my house? by Ashley Hamer (Listener question from Julien)
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/its-patient-o-not-patient-zero
ASHLEY HAMER: Hi you're about to get smarter in just a few minutes with Curiosity Daily from curiosity.com. I'm Ashley Hamer.
NATALIA REAGAN: And I'm Natalia Reagan. Today, you'll learn about how patient O became patient zero and what it takes for a species to evolve twice. We'll also answer a listener question about how those pesky fruit flies keep getting into your garbage.
ASHLEY HAMER: Let's satisfy some curiosity. When a disease spreads, it's up to epidemiologists to find patient zero, the first person to have the disease. That's not always easy. And in fact, the first person ever to be named patient zero for any disease, he wasn't even patient zero. He was patient O. Here's how a tiny misinterpretation gave us a whole new medical term.
In the early 1980s, gay men were dying from a horrific new disease, a disease that eventually came to be known as HIV/AIDS. The CDC asked scientist William Darrow to investigate its cause. He began to suspect that AIDS might be sexually transmitted, so he interviewed AIDS patients about their sex lives. In the process, he talked to three AIDS patients who all named the same lover, a flight attendant from Canada. That man, Gaetan Dugas, has since been immortalized as patient zero, the man who brought aids to North America.
The only problem is that Dugas wasn't patient zero, as in the first patient. He was patient O, as in a patient from outside of California. See, to maintain the privacy of the men in his study, Darrow identified them with a code that included their patient number and the city they lived in. Dugas lived outside the study area, so his city code was O.
Dugas wasn't branded with the name patient zero until three years after his death in 1987. Someone at the CDC mistakenly referred to Darrow's letter as the number zero, and it stuck. But only at the CDC. The name only got popular when reporter Randy Shilts adopted that terminology in his book and the band played on. Patient zero was a catchy name, and he didn't realize it was wrong.
But genetic studies later revealed the Dugas was not the first AIDS patient. The disease first made the jump to the United States from Cuba in the 1970s. He was, however, critical in uncovering the AIDS epidemic. Experts say he shared more names of his contacts than any other person in the study. But because of this simple mistake, countless books and movies since have unfairly blamed him for the AIDS epidemic. The best thing we can do now is set the record straight. And hey, at least this misinterpretation gave us a handy new term.
NATALIA REAGAN: Well, it's really fascinating. I mean, I never realized that it was O. It's something that seems like it's been around for hundreds or more years. And it's just-- it's younger than a lot of us are, so, wow.
When a species environment changes, that species often changes with it or it doesn't survive. Over generations, those changes can lead to the evolution of a whole new species. But what if that new species dies out? Can it evolve again? Now, this may sound ridiculous, but the answer is yes. It's called iterative evolution. And it's happened before.
First, some basics. When species develop traits that help them survive in their environment, it's called adaptation. Even though evolution is undirected, adaptation isn't random. Sure, the mutations that cause adaptations are, but evolution has a filter that prevents unhelpful mutations from lasting. That filter is known as natural selection. Basically, the individuals with unhelpful mutations won't last as long as the others.
Similar environments will mold different species into similar forms. This is why there are so many similarities between Australian and North American mammals despite the fact that they're distantly related. Think groundhogs and wombats. Sure one is a rodent and the other is a marsupial, but they look pretty similar and they fill similar niches. This is called convergent evolution.
Iterative evolution is similar but much more specific. This happens when a population moves to a location, like an island, and evolves to fill a specific niche, but eventually becomes extinct. If members from that same parent species find themselves on this same island with the same environmental conditions later on, this new population will follow the same evolutionary trajectory. They'll basically evolve the same species as before. It's so cool.
This actually happened on a group of islands in the Western Indian Ocean called Aldabra Atoll. The Aldabra rail is a little flightless bird with a slender neck and a red head. Their bills are long and pointed, giving the bird a narrow angular appearance. They evolved when white-throated rails from the mainland became stranded on the island. Because there were no predators and nowhere else to fly, these original rails of we became flightless ground foragers.
They thrived until 136,000 years ago when disaster struck, the island flooded, erasing the aldabra rail from existence. But 20,000 years later, guess what? Some more white-throated rails got stuck on the island again, found themselves in the same situation as the earlier settlers, and evolved into functionally identical species from the same ancestral lineage.
Paleontologists learn this from studying the Aldabra atolls very comprehensive fossil record. Fossil evidence reveals a play by play of the extinction of the first Aldabra rail and the speciation of its replacement. Now, before you ask, no, dinosaurs are super unlikely to evolve again. But hey, with climate change, who knows?
ASHLEY HAMER: Dun-dun-dun.
NATALIA REAGAN: Dun-dun-dun I don't know, Caroline, Jeanette, my little house dinosaur chickens, sometimes, I hear them vocalizing, and I think, a Velociraptor? Is there a Velociraptor in my home?
ASHLEY HAMER: Oh, man, I want to see you reenact that kitchen scene in Jurassic Park, just like Carol coming around the corner.
NATALIA REAGAN: I should film that. There would be Jeanette. She's-- I call her the ruthless assassin because I swear to God, like I'll just be sitting on the couch, and all of a sudden, I'll look over, and there's a chicken sitting next to me. Like, right there, and you're just like, where did you come from?
ASHLEY HAMER: We got a listener question from Julian, who asks, how do fruit flies keep getting into my house and compost? Am I eating fruit fly eggs all the time? Great question, Julian. Every region of the world has its own pests to deal with, but fruit flies? They're the great equalizer. Fruit flies can be found on every continent except Antarctica. And they love fermenting organic matter. That could be overripe fruit, rotting vegetables, booze, or even non-food ickiness, think drains, dirty trash cans, even sour mops and rags.
Once they find those spoiled spoils, they set up shop. They'll eat, mate, and lay eggs on the surface of the fermenting object. A female can lay 500 eggs at a time. And those eggs can mature into adulthood in just over a week. Yeah, they're survivors.
But the good news is that they only lay eggs on the surface of rotten fermenting stuff. So as long as you steer clear of fruits and veggies past their prime, you won't be eating fruit fly eggs. You can even cut off the spoiled part and eat the rest.
Even though fruit flies have a third of the neurons of your average housefly, they are phenomenal at finding fermented fruit. For a 2014 study, scientists from the University of Washington put fruit flies in a three-foot long wind tunnel and watched how they located the source of a delicious scent. Even when a light breeze dispersed the smell, the flies could find it. They'd make a beeline, or fly-line for it, when they smelled it. And they'd fly in a zigzag search pattern when they lost it.
They also used their eyes. When the scientists placed round objects in the wind tunnel, the flies landed on them to see if they were the source of the scent. To invade your kitchen, they combine that effective search strategy with another superpower. They're really, really small. They can get through cracks in the door or even through window screens if they're not tight enough.
If you do end up with an infestation, here's what to do. First, clean out your kitchen. Get rid of old produce, clean out your trash and recycling bins, and clean or toss old mops and rags. Then make a vinegar trap. Pour a little bit of vinegar in a glass or a jar, then curl a piece of notebook paper into a funnel shape and place it in the jar, pointy side down. The flies will go into the funnel, and they won't come out. Good luck, and thanks for your question.
If you have a question, send it in to podcast@curiosity.com or leave us a voicemail at 312-596-5208. I have tried the vinegar trap solution.
NATALIA REAGAN: And?
ASHLEY HAMER: And it works really well. You can even-- if you don't have vinegar, you can also use just like beer or whiskey, like that works, too.
NATALIA REAGAN: Oh, I'll use-- if I have wine that I didn't finish, I'll just leave it out.
ASHLEY HAMER: Yeah, and then you'll find flies in it. It's great.
NATALIA REAGAN: I used to joke that I had the alcohol tolerance of a fruit fly until I realized, oh, that means you have a very, very, very high tolerance because that's pretty much all they eat is fermenting things, so--
ASHLEY HAMER: Before we let you know what's coming up next week, I want to ask you one last time to do us a quick favor. Nominations are open for the 2020 Discover Pods Awards, and we won last year for Best Technology and Science Podcast. And we want to do it again, so we need your help.
Just visit awards.discoverpods.com, and click on Nominate Now. Then nominate your favorite show. We'll also put a link in today's show notes. It's free to vote, and it'll only take a minute. Everyone at Curiosity Daily really appreciates it. And with that, let's finish out the show.
NATALIA REAGAN: Well, before we recap what we learned today, here's a sneak peek at what you'll hear next week on Curiosity Daily.
ASHLEY HAMER: Next week, you'll learn about why the concept of zero is newer than you'd expect, how to worry more productively, how likely it is that we live in a computer simulation, parachuting beavers, and more.
NATALIA REAGAN: You had me at parachuting beavers, Ashley. Can't wait. OK, now, let's recap what we learned today. Well, we learned that patient zeor was originally patient O and was first used during the beginning of the AIDS epidemic, referring to a man outside of California, hence the O. The term patient zero was adopted three years after the man's death, but it was later determined that he was not patient zero after all. Though, this man was critical in helping doctors understand the spread of HIV, so he should be celebrated.
ASHLEY HAMER: It seems like the record is changing these days. I think more and more people are learning that Gaetan Dugas is not this villain in the history of AIDS. He's actually a pretty big contributor to us finding, maybe not a cure, but a way to help people live with the disease.
NATALIA REAGAN: Yeah. I mean, the first thing is understanding the transmission, and that's a huge part of combating any sort of disease. It'll be interesting even looking at COVID patients once we have a moment to step back and looking at the bigger picture because at first, it's really easy to just sort assign blame to certain areas or animals and things of that sort. But nothing happens in a vacuum, especially diseases.
ASHLEY HAMER: Yeah. And we also learned that some species can actually evolve twice, given similar environments. It's called iterative evolution. And it's been seen in flightless island birds, like the Aldabra rail. If only the flightless dodo would evolve twice, I would definitely like to see one of those at a zoo.
NATALIA REAGAN: Oh, I would love that. I would love to see them actually just living there, that would be so nice. That's a tourist draw right there, they've got the dodo. We've been talking about the dodo for years. And finally, finally, making its debut on Mauritius.
And lastly, we learned all things fruit fly. And we learned that we're not necessarily eating all these fruit fly eggs every time we eat a piece of fruit, even if we have an infestation of fruit flies. Usually, they're laying their eggs on the really foul pieces that are rotting and stuff. So well, I guess, don't eat rotten fruit, and you'll be fine, right?
ASHLEY HAMER: Pretty easy.
NATALIA REAGAN: And I guess, I mean, I've talked about this once before on the show just the idea of fruit giving off a smell of ethanol and how I've studied spider monkeys and they love eating fruit. And so fruit flies and spider monkeys both can kind of smell out [SNIFFS] that fermenting fruit and go for it. So that fruit fly has more in common with the spider monkey than we previously thought.
ASHLEY HAMER: Nice.
NATALIA REAGAN: Yeah. Today's stories were written by Ashley Hamer and Cameron Duke and edited by Ashley Hamer, who's the managing editor for Curiosity Daily.
ASHLEY HAMER: Scriptwriting was by Natalia Reagan and Sonia Hodgson. Today's episode was edited by Natalia Reagan and our producer is Cody Gough.
NATALIA REAGAN: Have a great weekend, avoid that rotten fruit, and join us again on Monday to learn something new in just a few minutes.
ASHLEY HAMER: And until then, stay curious.