Science Friday - Airborne eDNA, Beetle Jumps, Wordle Psychology, City Pigeons. Jan 21, 2022, Part 2

Episode Date: January 21, 2022

Identifying Animals Through Airborne DNA In recent years, the technique of eDNA—environmental DNA, or samples taken from the environment, as opposed to from a specific animal—has changed ecology research. Scientists have learned how to obtain eDNA from water samples, soil, and even the intestinal tract of other animals. Writing recently in the journal Current Biology, two different groups report that air samples collected with filters in a zoo can provide enough DNA to paint a partial picture of the species living in and around the zoo. After taking over 72 samples from 20 sites around a zoo in the UK, Dr. Elizabeth Clare and colleagues brought their trove back to the lab, and were able to identify 25 different species living in and around the zoo. Some were expected zoo inhabitants, and others were surprises—including DNA from a species of endangered European hedgehog. At the same time, a separate group of researchers performed a similar analysis on a Danish zoo, and achieved similar results. Dr. Clare joins Ira Flatow to talk about the research, and what the technique of eDNA might be able to bring to the world of conservation ecology.   These Beetles Go Boing There are plenty of insect species that jump—leafhoppers, crickets, fleas, and more. Some use powerful legs to take to the air. Others, like the click beetle, rely on a latching mechanism built into their bodies to build up energy, then release it suddenly. But writing in the journal PLOS One this week, researchers report that they’ve spotted a species of lined flat bark beetle (Laemophloeus biguttatus) that uses a different method to jump—the beetle larvae dig into a surface with tiny claws, flex, and build up energy, before releasing it and flinging itself into the air in a tiny ring. “It was really exciting to know that we had seen something possibly for the first time and definitely reported for the first time,” said Matt Bertone, an entomologist at NC State University and one of the authors of the report. The jumps themselves aren’t very impressive—only a few body lengths—but the discovery of a new mechanism that doesn’t rely on a specialized body part is intriguing. The authors aren’t quite sure why the larvae, which live under tree bark, have evolved the jumping behavior, but hypothesize that it may be to rapidly move when their bark habitat is disturbed. Bertone joins Ira to talk about the unique form of locomotion, and where the researchers might look next for the behavior.   This is Your Brain on Wordle Five letters, six tries to guess a word. That’s the simple conceit behind Wordle, the new puzzle game that’s sweeping the internet. More than 2.5 million people play this word game, its creator told NPR. The word changes each day and is the same for everyone who plays. Each letter guessed right brings the player one step closer to solving the puzzle. It’s free and simple, and according to many players, completely addictive. But why is such a simple game so compelling? And how does it compare to viral games of the past, like Pokemon Go or Words with Friends? Ira is joined by Dr. Matthew Baldwin, assistant professor in social psychology at the University of Florida in Gainesville, Florida, to unlock the reasons why Wordle both satisfies the brain and brings us closer to our peers.   Pigeons Are More Than Pests Pigeons lead much-maligned lives in our cities. They eat what’s edible from our trash, and live much of their lives at street level. So it’s no surprise, perhaps, that the name ‘rats with wings’ has reached the level of a cultural meme. But author Rosemary Mosco wants you to think again. Instead of seeing vermin, you might consider the pigeon much like a stray dog or cat. In her recent book, A Pocket Guide to Pigeon-Watching, Mosco details the history of pigeon domestication—as much as it can be known—including millennia of humans raising pigeons to eat, as well as cherishing them for their nutrient-rich poop. More recently, people painstakingly bred fancy varieties like the frillback and the fantail. And yes, your local city pigeon is descended from those beloved birds. Producer Christie Taylor talks to Mosco about the underappreciated history of pigeons. Plus, fun facts about their feral, city-dwelling kin, from the self-congratulatory wing-claps to the secret lives of baby pigeons.   Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flito. This hour has sort of an animal theme. We're going to be singing the praises of pigeons. I know you're going to want to stay with us for that one. And we're going to scratch our head at an acrobatic beetle. But our first story, well, it's all happening at the zoo. Suppose you want to know what species live in your local zoo. Well, you could look at the zoo's website.

Maybe ask people coming out of the zoo what they saw, or listen for the noises you hear. or maybe you could sniff the DNA out of the air. Writing in the journal Current Biology, two research groups report that they've been able to do just that, detect what animals live in the zoo by sniffing the air with a fan and a filter and sampling the DNA they trap, eDNA, as it's called. Joining me is Dr. Elizabeth Clare. She's an assistant professor in the Department of Biology, York University in Toronto, Canada, member of one of their research groups. Welcome to Science Friday. Thanks for the invitation.

Is it really as simple of setting up a fan and a filter and getting an air sample and sequencing what you find there? Pretty much. We're vacuuming the DNA out of the sky now and no one was more surprised than me that it actually worked. Tell us about your setup, please. We have a long history of working with this environmental DNA. Is any of the DNA that's shed into the environment? You don't take it directly from an animal source. And we've been filtering this. out of water. We've collected it from things like soils, from the gut tract of another animal to figure out what they're eating. And so we took the apparatus we actually used to filter water, and we aimed it at the air. It's a really simple device. It's a tiny little capsule with a very,

very fine filter in it. And it's kind of like the way you make coffee. When you're making coffee, the water goes through and the grounds get trapped in the filter. It's the same idea, only this time we're pulling air through. And anything that's in the air is being trapped on this tiny, tiny little filter. And then I can take it back to my lab. I can crack that open, take this really tiny, fine filter out, and use it like a tissue source. And it turns out it's absolutely full of DNA, and it's just floating around us. That's amazing. I know you looked at a zoo in the UK with this technique. What could you identify in the air? Well, the great thing about a zoo as a place to test this kind of technology is that the animals are this collection of non-native species.

had we gone to a farm and detected, for instance, a cow, we'd really not know whether it's the cow in front of us or a manure on the fields or cows hundreds of miles away. The zoo, there's only one source for that animal DNA in that environment. So if I pick up tiger, it's the tiger in front of me. There's no other signal I could confuse it with in the British countryside. So that's one of the reasons to pick a zoo in the first place. We took samples, yet their enclosures where they sleep, outside, where they roam around freely, and almost all of our samples turned up DNA.

We picked up about 25 different species of mammal and bird. About half of them were zoo residents that we expected to get because we were right there looking at them. The other half were this mixture of other zoo species that we were nowhere near that the DNA had sort of drifted towards us. We also picked up the things they were being fed. So if you're near a carnivore cage, we were able to determine their favorite food from the DNA in the air,

the thing they ate the most of. And then we picked up some of the native British wildlife, like ducks and squirrels, and even the European hedgehog, which is endangered in the UK and of serious environmental concern, and just exactly the kind of target we should be able to pick up DNA from, something we want to be able to determine if it's present or absent and track it, and there was its DNA floating around the zoo. Did some animals not show up that you expected to show up? Yes, both research teams, our team and the team in Denmark, picked up animals they expected to,

but also missed some. So in our case, for instance, there were several species of lemur at the zoo. One of them we never detected. One of them was the most common thing we detected. And at this point, we have no idea why that difference should exist. The Danish team, I think they missed hippopotamuses that were there. Wow, that's something big to miss. Yeah, and we don't know.

And that's true of many forms of environmental DNA. When you detect something, you can be pretty sure it was there. When you miss it, it's not always clear why you miss it. And is the whole point of this to do a census of what is at the zoo? Well, it was a test bed for us. The whole point of this is to be able to go out into an environment, sample the air, and determine biodiversity without ever actually seeing the animals. Most of the techniques we have for doing an environmental survey require that the animal be present when you are.

If you're using a camera trap, it has to walk in front of your camera trap. It goes behind, you'll never know it was there. If you're doing a visual survey, it has to be there when you're there. But environmental DNA is more like a footprint. They leave it behind. And so you can detect things that were there yesterday or the day before that. It gives you a longer period to sample. And it's one of the powers of environmental DNA that hangs around.

And so the real thing we want to do with this is to go out into the wild, be able to take air samples, and add this to our toolbox of things to do an environmental survey. So, yep, biodiversity, we want to be able to count things in the environment and know they're present. but probably the greater application is with rare things. Environmental DNA has been uniquely good at finding stuff that's rare, that you miss on the traditional surveys. And so the sort of immediate applications I can think of are invasive species, things that are moving into an area that you haven't picked up on your traditional surveys yet.

You might get their DNA first. Or the rare species, the endangered species that are so sensitive that you can't interfere with them. This is a totally non-invasive way of taking a sample. And you might be able to determine that they're still present, even when they're so rare, you don't see them very often. So we really think the true application is going to be looking for rare things. That makes me want to ask how far away, if you take it out into the wild, how far away, how good is it at detecting stuff in the wild? That's a really good question. The distance that the DNA travels is something we're trying to determine. And that's the other reason why the zoo

was picked as our place to test this out as a viable method. We know, where all those animals are spatially in the zoo. So if we pick their DNA up somewhere different, we can at least measure the minimum at traveled. We found dingo DNA at the Gibbon enclosure. We found zebrafinch DNA at the primate house. And so it allows us to measure at least how far it could have gone. And in our case, we know it was going a few hundred meters at least. We don't know the upper limit on that. There is some anecdotal evidence that might be traveling a lot further than that. But from our experiment, the zoo, at least 250 to 300 meters is reasonable. Tell us about the DNA a bit more.

Is it coming from the skin or the breath or something else? All kinds of possibilities. Well, we really don't know the source. We know that environmental DNA is shed all the time. It's been found in almost every substance we've looked at. Strange things like honey traps environmental DNA, rain, snow, soil. People even spray the surfaces of leaves and collect the water that runs off to get DNA that's settled. Where it comes from is more complicated. It's probably every source you can think of.

bits of skin cells being shed, tiny fragments of hair, urine, feces, maybe even breathed being breathed out, carrying DNA with it. It might even be the fragments of DNA that are left behind when a cell dies and dumps its contents into the environment. So it could be absolutely anything. Any way that you drop a tiny little piece of yourself behind is going to leave this trace that we can now collect. Interesting. What about this other team? There's another paper

that goes right alongside with yours. Well, this is the wonderful thing about this story. We had finished our paper and we'd put it up on an online server to share with the scientific community. And then another paper appeared that was absolutely identical.

Same experiment, a different zoo, a different group of people. And it appeared within 48 hours of hours. And so we contacted the other team and discovered that we both done the same experiment, at the same time, perfectly replicating each other's data with no knowledge. It's the biggest scientific coincidence I think I've ever heard of. And so we contacted the other group. And rather

than getting to some sort of race to see who could publish their paper first, we started to coordinate. And over the course of a couple of weeks, we contacted editors of the scientific journals directly and said, we think you're stronger to have two. If you've got some crazy idea, it's nice to have someone else who's done the same thing and shown it works. And so, So we worked with the other team to get them published on the same day at the same time. And the other team found the same things we did and total coincidence. But it's really how science is supposed to work. We're supposed to replicate each other's data.

And this is an incredible case where two groups, our group in England and the group in Denmark, did the same experiment in the same way, at the same time, and found the same thing and have managed to publish them in the same journal on the same day. You know, we've got these rapid tests for various diseases like COVID. Do you think it'd be possible to design a rapid test for DNA in air, a sort of a paper that turns color if a certain species is nearby? That's possible. I'm not sure how widely applicable it would be.

If there's something in particular you're looking for, you can do that. And I know there's sort of assays exist. But in general, this sort of DNA is being used for finding everything. And we do have mobile labs that can do this. I have gone out into a middle of a jungle and sequence DNA with no internet and no lab and no source of even a cell phone signal. We've been able to do that. It's not very practical. It still takes a couple of days, but it's certainly possible.

This sort of technology is advancing so quickly that I think very soon my lab and others like them will be doing just that. Go to an environment and do all your collection and sequencing on site. Never go back to your lab at all. Well, would you be just as excited if you found and collected DNA that you have never seen before? Absolutely. I started off my career as a taxonomist describing new species and doing that using DNA as a primary source of information. And so if we find something that's never been seen before, that's not uncommon in the world of biodiversity science. Most animals don't have a name attached to them. Most of the biodiversity of the planet is unknown. So if we can collect DNA and start saying, well, we think we've got something new here,

it'll tell us where to focus our other sources of information gathering to learn about it. I'm part of a very big global consortium that is trying to document biodiversity with DNA called bioscan. And that's exactly one of our objectives, is to try and document the unknown things and environments. Am I thinking too big in thinking that the end goal of your research and other research is to have a census of the whole planet? No, that is the end goal. And it's surprising to most people that we don't have that. When I lecture my students about biodiversity,

I usually point out to them that biodiversity scientists struggle to even estimate the number of species on the planet to an order of magnitude, somewhere between 10 and 100 million species currently, but we don't know which end of the spectrum we're closer to. So we can't even estimate how many species are there, let alone count them and actually know what they are. And about 90% of that has never been seen by science.

And so that's a huge problem for us trying to document global biodiversity. We don't even have a good estimate of how many things are yet to be found, let alone have an inventory we can use to identify things. And so we need all these new technologies to help us advance that goal quickly at a time when species are going extinct very, very fast. To not even know they exist before they disappear is, to me, a real problem in science. Very, very interesting. We wish you great luck in your efforts to find out. Thank you. Dr. Elizabeth Claire, assistant professor in the Department of Biology at York University in Toronto, Canada. We're going to take a break, and when we come back, a newly discovered method of beetle locomotion, a new way to jump. You'll want to see this jumping larvae. Stay with us. This is Science Friday. I'm Ira Flato.

If you're a regular listener to our show, you know that we like to find unusual creatures, even charismatic ones. And lots of those are creepy crawly things or real jumpers. Think leaping leaf hopper or a springy cricket. Well, this week, we found another one for your consideration. A common beetle that you can find in a dead tree on your lawn whose larva are able to jump in a way that hadn't been described before. This work was published this week in the journal PLOS 1. Joining me now is Dr. Matt Bertone, an entomologist at NC State University, and one of the authors of the report. Welcome to Science Friday.

Thank you for having me. Okay, tell us about this beetle. What is it? Where does it live? Yeah, so it's a little fairly nondescript beetle, and what we described was the actual larval stage, behaviors of the larval stage. but this species is common throughout eastern North America, fairly small and kind of obscure typically, so people don't usually see it. The adults are small brown beetles with a very flattened

body and two spots on the body, and the larvae are just small, worm-like critters that crawl around under the bark of dead trees. And you found this one actually on the bark on campus, right? Yeah, that's correct. There was a standing dead oak tree that was developed, some fungus on it right outside of our building. And of course, because I pass it every day, I had to just collect some insects from it, especially for the specimens and my photography. This is what you do. Yeah, yeah, this is what I do. So regular day for me. Let's talk about what makes this beetle and the larvae so different from other jumping insects. So many adult insects jump. You think of crickets and grasshoppers. Even adult beetles, there are many

species that jump and they usually have large hind legs and they just kind of launch off the surface. What this larva does, though, is very interesting. In fact, it builds up energy in its body and latches onto the ground with its claws. And as its body builds up energy, it releases those claws and this causes the insect to somersault into the air a short distance. And there's nothing weird about the claws then? Nope, they're fairly typical larval claws, nothing special really about them. Well, if they live under the bark, why do they need to be able to jump? They're not going to be jumping any place under that bark, are they?

Yes, so that's a great question. And we've been trying to figure out exactly why. The logic would be that since it's under bark, it doesn't need to jump, of course. So part of what we thought was maybe this is some artifact of a behavior they do under the bark. There are other larvae that are known to wedge push, so they kind of bump up a little bit under the bark to give it more space to crawl under. But we didn't think that was really the case. Why develop that behavior if you're under bark most of the time?

Other beetles that have kind of jumping larvae often do that to escape predators or parasites. But we noticed that these larvae, you put them down the ground, they'd crawl a little bit, and then they'd hop on their own. You wouldn't have to kind of touch them or do anything to make them jump. So it came down to us thinking about their, you know, kind of their lifestyle. And, you know, my ideas and our thoughts were that this source, rotting wood and trees that are standing with bark that's kind of falling off could easily expose these larvae. And they're light-colored. They're on a dark surface.

They could easily be picked off by predators. So one of my hypotheses is that they do this to get away from their sites either when exposed or just because they want to. And it's more energy effective to do that than the crawl. Now, you mentioned before that they're not, how shall we say, great jumpers. And so the height of their jumping and their jumping ability, their talent for jumping is not what interests you, but it's the way that they jump that interests you, right? Yeah, so they're definitely not record setters. They're definitely not even super impressive. They are when you see them with the naked eye because it's fairly quick. But when we actually went to record the distance and the heights, they were not jumping very far.

really. But beetle larva jumping are really rare and beetles are a huge group of insects. Over 350,000 described species on earth. And so you would think you would find it more commonly, but it's actually fairly rare in beetles. And then the second

aspect was the way they jumped using this latching mechanism with the ground is very unique. And they do this pretty quickly because I was watching a video of your colleagues showing us how they jump. you had to use a really high-speed camera to see the details.

Yeah, so Dr. Adrian Smith at the North Carolina Museum of Natural Sciences, downtown and Raleigh, one of his specialties is filming high-speed videos of insects. And so this is a great collaboration. So when you see the jump with the naked eye, it's very quick. When we showed it at 3,500 frames per second, we could see the basics of it, but he actually went to a special lab to get filming of 60,000. frames per second in which we were able to see even more details. Wow. Now, does it matter what surface they are on if they have to use their claws to sort of set the spring in their body, right? Does it

matter that they're on a slippery surface? So that's actually one of the lines of evidence we used to show that this is actually a latching mechanism. Adrian did film some on plexiglass and glass surfaces and they were unable to jump. So that leads, to believe that they really do need something to latch on with their claws. Do you get the impression that this is a talent that, evolutionarily speaking, they had to develop a little bit later in their evolution because they just don't have the jumping body style that the other big jumpers have? Yeah, this seems to be, I'm not sure when they developed it,

but it does seem to be a fairly simplistic way to do it if you think about it because most insects have claws, and they're crawling on the surface, they can grab down. So it really didn't require any specialized anatomy that in many insects that do have those special organs to latch and jump, they didn't have to evolve those. I kind of find it interesting that after the jump is finished, they sort of curl up into a little ring and then bounce around as they land. It's like a tire.

It reminds me of a tire, right? Exactly. I love the little bounces when they hit the ground. I don't know how they feel when they're doing that. Luckily, they're pretty light animals and they can resist it. And yeah, it's pretty erratic. They're jumping. They don't really aim somewhere. They're not, you know, they're not trying to get somewhere special, but we think that it helps kind of introduce different areas for them to explore. Do you have any feeling about what actually makes them jump? Loud noises? Do you have to poke them? what's the stimulus there? Yeah, so they seem to just jump when they were kind of exposed out in the open crawling around.

That was what led us to believe that it wasn't so much them directly responding to some kind of predator or parasite. You could grab them with the soft forceps or touch them with a paintbrush and they'd crawl along and jump. But even if they were put out on the surface alone with no kind of stimulation like that,

they would crawl around for a bit and then jump. And so that's what we were able to observe with the specimens we had. But unfortunately, we don't have a lot of specimens, live specimens, to experiment with. So a lot of that stuff is still a mystery. And to bring that up, to take that one step further, I noticed that when you posted this behavior online, other folks had seen it to in their species. Yeah. So you found other comrades.

That was one of the greatest things about this. Actually, in fact, it was really interesting. So we talk about these jumping larvae. Under the same bark with these larvae, there were also fly maggots. And many maggots are known to jump. And what they do is they latch their mouth parts onto their rear end and then stretch their body and then release and releasing that energy. So they use a body to body latch. But at the end of a video that Adrian produced about those jumping maggots, he alluded to and showed a clip of this beetle larvae jumping, you know, just as a teaser.

and out of the blue, he got a message from a Japanese researcher, Takahiro Yoshida, and he is a world expert on this group of beetles, and because he collects them, he had noticed one of his larvae doing the same thing, and this was actually from a different genus across the world in Japan. So it's really interesting that it evolved at least twice in these beetles. So it's possible that this is more common than you know about. Yes. And that would be great to find out how common.

But again, these are very obscure little critters that, you know, not a lot of people pay attention to. Well, we have a big audience. So if people are listening and they want to do some of their own research, can they look for these under the bark of their own trees? They could. These beetles are associated with kind of micro fungi that are under dead and dying trees, the bark of them.

They can be found under the bark of logs on the ground, things like that. They're not uncommon, and there's other groups of beetle larvae and insect larvae that would be associated with those fungi. So you're going to find a lot of different things to observe if you do that. I would just make sure to be careful to leave some habitat left and to replace bark and things like that, to just make sure that the insects and other orthopods have a good home. Do they have a jumping signature that if I peeled up the bark and I looked and I saw there were a lot of other insects and larvae under there that I would say, hey, look, it's jumping in a certain way. That's the one. Yeah, so I'd be interesting to see, you know, opening up the bark and seeing a bunch of larvae. If you could just sit back and watch and

see if they jump. You know, we as scientists would always want to collect those specimens then and get them identified for sure, which was actually the first step of the process was finding out what type of larva it was because we actually did DNA work to link it to the adults and we got confirmation through identification keys. It was really exciting to know that we had seen something possibly the first time and definitely reported for the first time. You mean the reporting the jumping of it? Yeah, exactly.

So, you know, we don't know without publications whether people have seen it before. You know, somebody could have just been tearing up as a bark, saw a little larvae or grub jumping around and they're, oh, well, whatever. But recognizing the importance is really, really part of it. of it. Now, I noticed in the video I was watching that you guys went through great trouble to scan the larva, to look at poke it, see in every direction that you can. Is there still something you don't know about it that you would like to know? Yeah, I think we would definitely like to have or would have like to have more specimens to kind of do some more experiments like manipulating them

on different surfaces or doing different experiments to see what might cause them to, do this jumping behavior. Again, we just, you know, they're very ephemeral. It's hard to pinpoint where they're going to be and collect a number of the specimens to experiment on. It's not like a pest species that's so common or something that we keep in colonies. So that's where one of the difficulties comes about.

So you don't want our listeners sending you their samples that they're collecting. I mean, I'd love to see some. I mean, I'd love seeing the diversity of all different things under there. I also don't want everybody to kind of go out and collecting all these things without kind of proper methods and whatnot. But yeah, I would love to see if people have photos of these things or videos or have the specimens alive, reach out to me, and I'd love to help you identify them. But there are a lot of different ones under the bark, so you can make it confused. Okay, well, there you go.

There's the challenge to all of you. If you've got something, you can contact Matt at NC State University. Thank you, Dr. Baton, for taking it to have to be with us, too. Of course. Thank you very much to you too. Dr. Matt Bertone, entomologist at NC State University in Raleigh, North Carolina. And if you want to see the Jumping Lorva video I mentioned, and you should because it's totally worth it. You'll find it on our website at ScienceFriiday.com slash jumping. This is Science Friday from WNYC Studios.

If you've been on social media at all over the last few weeks, there's a good chance you've seen the new game that's sweeping the internet. Wordle. Yeah, more than two and a half million people play this word puzzle game. You have six chances to guess a five-letter word. The word is different every day and is the same for everyone who plays. Every letter you guess right brings you closer to solving the puzzle. It's free, it's simple, and some people say it's totally addictive. The question is, why is such a simple game so compelling to so many? Well, for the answer, we're turning to psychology and my next guest, Dr. Matt Baldwin, assistant professor in social psychology, University of Florida based in Gainesville.

Welcome to Science Friday. Hi there. Thanks for having me. You're welcome. Before we really get into it, Matt, I have to ask you, are you as addicted to Wordle as many people have become? I am unashamedly addicted to Wordle. How long did it take? Probably right away. I think I saw the green and yellow. yellow boxes showing off on my Twitter feed around Christmas time. I think from the first puzzle,

I was addicted. Yeah. Wow. Wow. So as a social psychologist, to explain this to us, what is it about this game that really appeals to us and obviously to you? Sure. I think there's a lot going on, but I think there's two kind of main components to the game that I think really connect with us. On the one hand, Wordle is a shared experience, right? So we see our friends play. it. We get to share our results on social media. And when we do this puzzle together, we're all working toward the same goal. We're all trying to solve the puzzle at the same time on the same day. And I think this creates a sort of common in-group goal. And it allows us to share this experience with others. And we know from psychology research that shared experiences are really

meaningful to us that shared experiences are amplified. When we feel an emotion or watch a movie together, we experience those things in an amplified way. So I think on the one hand, it's like a group event that connects us. On the other hand, it's a creative, insightful, and flow-like experience. There are many elements of the game that make it fun and engaging. There's optimal levels of challenge. We get this insightful aha moment toward the end when we guess the puzzle correct And I think this is a very rewarding experience. Now, of course, there are other games that we all work together. I'm thinking of Pokemon Go, words with friends, even crosswords or chess.

Is there something that sets wordal apart from those games in terms of how our brains react? I think it's because we're all working toward the exact same thing. So the word is the same for everyone. And the number of guesses are the same for everyone. And so it is a truly shared experience. There's not a lot of variety there. And, you know, psychology suggests that when we all work toward a common goal, we really coalesce around that goal and sort of group boundaries are broken down and we come together.

And, yeah, in Pokemon, there's a lot of variety, even in Sudoku or words with friends. It's not necessarily a common goal despite being a shared experience. So I think that's one thing that sets world apart. So are you saying that the sharing part, the fact that this is a social community that we have, that we have not had decades before, is integral to the success of this game? I would say that's one of the main components, yes. I think that especially now when most of our lives have turned to online spaces and we're maybe all really grasping for some kind of social cohesion, it makes sense to me that a very simple common goal like this and the ability to, sort of check your own experiences against others and get some verification that this simple little thing is really fun and everyone else thinks it's fun. I think it's a very welcomed experience for people right now, especially, several years into the pandemic. And it has created

a very cohesive, connected social group online in a way that maybe nothing has done so far. Thank you, Matt, for taking time to be with us today. Fascinating ideas about Wirtle. I appreciate it. Thank you. Dr. Matt Baldwin, assistant professor in social psychology at the University of Florida based in Gainesville, Florida. We have to take a break and when we come back, everything you never knew about city pigeons. This is Science Friday. I'm Ira Flato. I can't believe I'm asking this. I'm asking you to consider the city pigeon. Yes, it's the bird that roams the streets of urban areas like a straight dog or cat. It eats garbage. It poops on our windowsills and nests in our eaves. And you may have a certain derogatory nickname for pigeons. And I bet I know what that is.

But before you write these birds off are good, producer Christy Taylor is here with a plea to just spend some time watching them. Hey there, Christy. Hello, Ira. Now, I know you're a member of our small but mighty sci-fri pigeon fandom. Ooh, yep, that's right. Convince me, why are we watching pigeons? First of all, it is a long story. And second of all, there is quite a bit of poop involved. I hope you're still with me.

Poop and pigeons. Oh, why am I so surprised? You're going to need a little bit more arm twisting on this one. Okay, well, hear me out. Pigeons have actually a millennia-old relationship with us. They're not just wandering around our streets, but we domesticated them, much like dogs and cats. And we enjoyed them both as a food item and a fertilizer for thousands of years. That's where the poop comes in.

I see. They poop so we can eat. As a result, we now have feral pigeons, the escaped offspring of our tame livestock in every major city in the world. Rosemary Moscow is a science cartoonist and author, and her latest book is a pocket guide to pigeon watching. It's all about our long, long history with these birds. what you can observe about them when you see them out and about, like how to find baby pigeons. And the first thing we talked about was the big W, why pigeons deserve more love than they get. Personally, I got excited about pigeons really, really early on because I was a birdwatcher and I lived in a bunch of major cities. So when you're a birdwatcher, you know, and you're living in an urban

environment, you notice the pigeons. So I always thought they were kind of cool. But then I started to delve into their history, and I realized how incredibly misunderstood they are and how unfairly we've been treating them. And that just blew my mind, and I felt like I really needed to tell everyone that hidden history. So you're talking about pigeons in our streets, their descendants of domesticated pigeons. You really want us to think of them like stray cats or dogs, right? Yeah, exactly. There are so many similarities. With pigeons, there are thousands and thousands of years of domesticated history, just like when we domesticated the dog or the cat, you know, thousands and thousands of years ago for various purposes. But yeah, we don't know exactly when it

happened. And it probably happened in lots of different places in lots of different times, which is also how it happened with dogs and with cats. With pigeons, many people have completely forgotten that they were once our precious domestic friends. And I think that's really wild. You keep mentioning dogs and cats. We know that Those animals have helped us drive away vermin, protect our settlements, even help us hunt our own food over time. And there's also companionship, of course. What did we get out of keeping pigeons? Right.

When you look at a pigeon, you don't think, oh, gosh, look at that. You know, I can write on that. Or I could, you know, protect my crops or something. But they are so, so, so incredibly useful. So I like to think of them as the Swiss Army knife of birds. They were probably initially domesticated for their meat. People all over the world still eat pigeons, and North Americans ate them up until pretty recently. But there are so many other uses.

Their poop is a really important fertilizer. They carry messages on their legs, long, long, long distances. You can race them, and you can even breed them in all sorts of cool sort of shapes and colors and patterns. Again, a lot like dogs. I want to talk about pigeon poop because that was one of the things that started out maybe as a side benefit of keeping pigeons but turned into a whole other reason to keep them. Is that true? Yeah, that's absolutely true. Pigeon poop was really like brown gold. So pigeon poop is a really, really potent fertilizer and it's excellent, especially if you're living in an area with desert soils that maybe need a little bit more of a nutrient influx. It's great. stuff. So for a long time, people in the Middle East and in the Fertile Crescent were using pigeon poop to grow all kinds of, you know, beautiful fruits and vegetables. And then that usefulness

of pigeon poop sort of exploded, not to use a pun, when people discovered that there's this stuff in pigeon poop called saltpetre that can be used as an ingredient in gunpowder. And so in England, especially in, you know, the 17th century, these gentlemen called salt Peter men, were marching across the country at the behest of the king and knocking over dovecoats and digging up all of the pigeon poop. And this was ruffling a lot of feathers. You also write that pigeons can tell us part of the story about even European colonialism. Why is that? So back in the day, in North America, there was a species called the passenger pigeon.

And I'm sure, you know, many, many, many people have learned about the passenger pigeon and the tragedy of how this species was destroyed. For many, many, you know, generations, they were sustainably managed by indigenous people who lived here, and they were eaten. And so when colonists came over, they went, hey, these things look really delicious and destroyed a lot of those passenger pigeons, and they sadly went extinct. And the really wild thing is that those colonists considered pigeons to be so important that they brought over their own city pigeons.

So essentially, there was a replacement of this passenger pigeon. And nowadays, we've forgotten why we even brought over the pigeons because we've eaten factory farm chicken for a while. So it's this sort of this history of replacement and then forgetting that I think tells us a lot about colonialism. I want to talk then about the city pigeons that we see today. They often have this one very standard look, you know, blue with that black bar on the wing, beautiful iridescent neck. But there's a lot of variety that we actually see if we really look closely at the the pigeons in our cities, right? Different colors, different patterns. Where does all of that come from? Should we assume that they're crossed with something like a fancy breed of some kind?

Yeah, absolutely. This is one of the most remarkable things about pigeons. And I think it gives pigeon watching its real focal point is that, again, much like with groups of feral dogs, you'll see lots and lots of different shapes and sizes and colors in our city pigeons. And that's purely because we took a whole bunch of breeds, some of them escaped and they crossbred. And so you'll get all kinds of beautiful colors from browns to whites to different blues. And you'll see these different colors sort of in different levels of intensity and in different patterns. And that's totally because we took, say, some chihuahuas and some great danes and all these different pure breads. And they interbred on our streets. And in fact, there's something else going on, which is that at some point,

again, kind of lost to the mists of time, folks crossbred this species in Africa called the speckled pigeon with our city pigeons. And so you'll see a lot of city pigeons with these speckley wings. And that's because of this hybridization that happened at some point that people did. We don't know why. And those genes are in there. So our history is written all over our city pigeons. That's amazing. The speckled ones are some of my favorite ones to see, actually. Yeah, they're beautiful. But there really is. just this incredible variety of all of these colors. And not all of these varieties did super well when they would escape into the city. So you won't see some of those more fantastical varieties.

But you will find, for example, city birds that have feathers on their legs. And that is one of those things that comes from those purebred birds and probably gives them a bit of an extra toasty warmth in the winter. Let's talk about anatomy for a second. I couldn't help but notice that one thing that they do very differently from mammals is how they breathe. Pigeon lungs, as you write, don't expand. How the heck does that work? So bird lungs, you know, are paired just like our lungs, but they don't open and close. There are these air sacks all around the lungs that channel the air through the lungs. And these air sacs stretch into the wings. They're really, really amazing. There's tons and tons and tons of them. And so what this does is it makes birds really, really, really, really

efficient at pulling oxygen out of the air. And this helps fuel their flight. So I would say that their respiratory system is truly, truly incredible. Perhaps on the too familiar side of things, though, they also make milk, which first of all, that's weird. Second of all, maybe kind of gross. Third, I don't see any little pigeon utters as far as I can tell. So what's going on with that? Yeah, one of my favorite things to do is to tell people that pigeons make milk and then sort of pause. and I know exactly what's going on in their minds because they're imagining, you know, where are the utters, which is totally reasonable. They don't have udders.

They do make milk. It has a lot of similarities to human milk, but it's produced in this area of the esophagus called the crop. So it's sort of secreted into this area and puked into their baby's mouths. Okay, okay. But it's got proteins and fats, and it's stimulated by a hormone called prolactin. And it's really essential for, you know, their baby's development for the first few days. It is apparently chunkier than cow's milk.

And so I wouldn't recommend getting yourself a cup of it, but also it would be really hard to milk a pigeon. So you don't need to worry about doing that. Well, I stand by the gross assessment from earlier. Okay. That's fair. Why don't pigeons fly more? I feel like I've seen them walking upstairs, crossing the street in the crosswalk. people have observed them on the subway sometimes.

What's up with that? Pigeons really are walkers. They fly very, very, very well. They'll fly to and from their nests, or they'll fly in response to a predator. But flying is pretty exhausting. I mean, why aren't we all running around all the time at top speed? Fair question.

It's an essential tool, but pigeons really did evolve to be ground foragers, which I think is a lot of why people think they're sort of gross, is that they're just walking all around on the ground. And they are usually walking around on the ground looking for grain and that sort of thing. And they'll even sometimes sleep on the ground. And then when they nest, they'll nest on flat surfaces. So they are not birds of the forest.

And you'll never see a pigeon nesting in a tree or very, very rarely. Is there a behavior that you haven't yet managed to see that you know about that you think is really cool? So you'll often hear pigeons sort of clapping when they take. off. And what they're doing there is they're flinging their wings overhead and kind of slapping the backs of their wings together, you know, potentially to tell other pigeons, hey, there's something scary here. But there's another reason that they clap. The males do something called a post-copulatory display, which is something that a lot of animals do and maybe even some humans. And we don't really know why they do this. The pigeons will mate. And then the male pigeon will take off and he will fly back and

forth and clap for himself, basically. So he'll be flying along and do a series of like, woohoo, I'm so great sort of claps in the air. If we can't see the pigeons, but we can hear them, is there anything that they do that's beyond the usual just, cuckoo, I'm here? Yeah, their vocal world is surprisingly complicated. I mean, they don't sing fancy, fancy songs, but they make a lot of different sounds. So I mentioned the clapping. There's also a wing whistle where they'll take off and they'll make this sort of whistling sound that tells the other pigeons, you know, there's something dangerous and, you know, we all need to take off now. And then there are the cooings. So there's one called the display coup. And that's the coup that you will hear when a male

pigeon is kind of bobbing up and down and showing off to his pigeon wife and the female pigeons will sometimes do it too. And that's kind of the standard coup. So that's really hard for me to do. So sort of like, what to gru? Oh, wow. That wasn't really. Thank you. Thank you so much. I don't think I'm going to win any pigeon wives. Who knows? Maybe she'll come someday.

Someday, wistfully looking out at the window. But then they make another coup, and this one is truly wild. So I first heard this when I was staying at a friend's house in New York City. It's called the advertising coup, and a male pigeon will make this sound when he has found a really cool spot for a nest. So that sounds like this. It sounds like, ooh, woo. So it sounds like a guy going, woo, basically. And that is their way to say, hey, check it out.

I have a really cool nest spot. So you probably will hear that at some point. And it's not a person. It is a pigeon. Is that the like, check out this Zillow listing that I just found? Exactly. Like, oh, we may never actually rent this place or purchase this place. It's $5 million.

But look how good it is. We could raise so many pigeons here. Just a quick reminder, I'm Christy Taylor, and this is Science Friday from WNYC Studios. Talking to author and illustrator Rosemary Moscow about her new book urging you to go watch pigeons. So as you mentioned at the start of this conversation, pigeons kind of get a bad rap, and some of it has to be because they're on the ground, eating our trash. But there's also this fear that they're making us sick. Is that legitimate in any way?

Should we still maybe handle with care if we're lucky enough to even touch a pigeon? One thing that I found really comforting about reading a whole lot of different studies about pigeons causing illness is that it's really a relatively rare thing. Pigeons can carry some illnesses they could potentially pass to us. Definitely be very careful if you work with pigeons a lot or if you have any conditions that result in being immunocompromise. But pigeons in the park are really not going to cause you a lot of issues. There's a real misconception there and it was partly born in the 1960s. When pigeons at that point had sort of fallen out of favor, they were sort of obsolete technology. We weren't really eating them. We weren't using their poop as fertilizer. We were sort of over them.

They were kind of like fax machines are today. And at the same time, there were all these feral birds everywhere. So people sort of thought, you know, ew, gross. These creatures are in our space. In the 1960s in New York City, they were blamed for a meningitis outbreak. And it was this tragic thing. A couple of people passed away. It was not because of the pigeons, but City of Fish, said this kind of miasma of pigeon filth was spreading all throughout the northeast. And there was a lot of fearmongering. And that's partly why we think pigeons are really gross. But they're really not the major health risk that we all worry they are. Do you have any last pro-pigeon propaganda to throw our way? Yeah. One thing that I love to stress is that pigeons used to be considered a luxury item,

basically. So for hundreds and hundreds of years, you know, in places all over the world, they were considered something that only the rich had, kind of like a Ferrari of birds. And in some places, they were used to reinforce class distinctions because only the rich were allowed to keep pigeons and the poor were not. I'm not saying we need to go back to that kind of horrendous situation. But I think it's really important for us to think about how, you know, we used to think of animals and how we think of animals now and how there's always kind of changes throughout history. So pigeons are super cool and fun to watch. And also they can tell us a lot about. at ourselves. So I think their gifts just keep on giving, even if one of those gifts is crap.

Well, I'm going to leave it there. Thank you so much, Rosemary. Thank you so much. This is really fun. Rosemary Moscow, author of the new pocket guide to pigeon watching. And if you are as excited about pigeons as Rosemary and I, and maybe you have a big brain full of pigeon facts, you can catch Rosemary at next week's SciFri Virtual Trivia Night. The winner gets two free copies of her book, a pocket guide to pigeon watching. And even if you didn't win, I can guarantee you'll have fun with the nerd flock. That's Wednesday, January 26th at 8.30 p.m. Eastern. To learn more, visit our website Science Friday.com slash trivia. Huh. Sounds like I'm going to have to sneak into that. Try my luck. I got to admit, Christy, you really made a surprisingly good case for pigeons. Thanks, Ira. You can't see,

but I am positively preening right now. You missed a spot. Christy Taylor, sci-fi producer and stuntch member of Team Pigeon. Thank you for joining us. You're welcome. That's about all the time we have for today's show. Of course, if you missed any part of this program or you'd like to hear it again, subscribe to our podcasts or ask your smart speaker to play Science Friday.

Have a great weekend. We'll see you next week. I'm Ira Flato.