Evolution and the City: The Beasts

primates for our closest evolutionary relatives. Yeah, I would say physiologically, if you look at comparative anatomy, and of course genetically, we are the most similar to primates like chimpanzees and binobo's, and they actually are known to be our closest relatives

in the animal kingdom. But I think if you look at humankind in a different light, if you don't just look at the individual body plans and compare one individual to another individual, but if you compare the entire species ecological and trophic profile as a whole population, you can make a very different case. We're the most like ants, and we became more like ants starting around ten thousand

and maybe thirteen thousand years ago. Before this time, I would say, there's really no way to compare us to ants at all. We just weren't very antlike, except maybe that you could say we were a social species. But you know, maybe ten thousand to thirteen thousand years ago humans first started practicing plant and animal agriculture, and over the years more people began to transition from a nomadic hunting and gathering way of life to a settled agricultural

way of life. And of course the introduction of farming, we know the story. It changed everything. It allowed for surpluses of food resources, specialization of skills, education, writing, construction, invention, and so on. And because all of these processes were made possible by keeping people and resources close together with continuous interconnected access to one another, this meant the birth

of cities. And I would say ever since then, the construct of the city, the idea of the city as a technological thing and as a social organizing principle, has been one of the biggest influences that has changed the way human beings relate to the earth. Now, we're all pretty familiar with this story of of urbanization from a human point of view, but from a biological or ecological point of view, It is an extremely strange and interesting

thing for us to do. And it's also extremely similar to what ants do when they form colonies and build ant hills. It is yeah, when you when you start thinking about it, this this artificial habitat that they can they construct to live in and in, you know, in in in in some cases, grow their food in, cultivate their own crops. Yeah, almost all creatures on Earth adapt to their environment. The environment is one way, and the animal over time evolves to be a best fit to

the environment around them. But humans and ants and some other creatures you could argue, like bees and some other use social insects, termites to some extent, don't adapt to their ecosystem as much as they build an ecosystem for themselves. They engineer their own environments in their own ecosystems, and of course, in both cases ant hills and human cities, these ecosystems are not hermetically sealed off from the rest of the world. They're poorous and connected to the rest

of the world. And what this means for ants, of course, is that they have entire classes of organisms that have specifically evolved to thrive within the ecosystems created by the ants, the same way that a fox or wolf, spider or any other creature would thrive within its natural environment. There are organisms that that have evolved to thrive within the ant engineered environments, and these organisms are called myrmica files. Yeah. There. Then there are a number of different species that the

one could spend time with. Here, Uh, a couple that that came up from me though, Uh, there's one. Uh. This is an example of research before the p Favieri deetle. So it uses a complex dance of both chemical and auditory mimicry to convince the ant population that it's one of them, even as it crawls in into their abode and feeds on their larva and benefits from the colony's protection.

But as Carl Zimmer highlights in his New York Times piece on a study concerning these beetles, the deceptive beetle may even mimic the queen from time to time in order to receive royal treatment, but it otherwise knows to leave the queen unharmed. It doesn't seek to decimate its host colony, but rather to thrive within it through perfect mimicry.

Uh and uh. I explored this, by the way, originally because I was interested the Monster from John Carpenter's The Thing, because one of the ideas that is explored in the film, and I think also in like a comic book sequel, is that if this thing gets gets out, if it escapes from this frigid base, it's going to just decimate the world in no time. Right, it will mimic all life forms and just take over the entire planet. Right.

But would it necessarily do that? Right? I mean, I mean, you can certainly make a case that it's an alien contamination, So who knows what it would do to to to what is to it an alien ecosystem. But I think if we look to examples like this from our natural world, we can we can see that, well, maybe it wouldn't necessarily overrun the planet because it needs to live at harmony within the host ecosystem. Yeah, it needs an ecosystem to survive off off of. It can't become the whole

ecosystem itself. Yeah, So it's they're going to be essentially self imposed limits on what it will take over and destroy. Now, that's far from the only example of mermai else that have evolved specifically to survive and thrive within the environments created and maintained by ants. There are thousands more, right, One that I ran across that was interesting is the

oak blue butterfly. So these don't reside really within the colony so much, but the butterfly larvae may chemically mimic or camouflage themselves and be accepted by the what are sometimes called the plant ants on their host plant, the ant plant, or macaranga as it's called. So essentially what's happening here is the chromato gaster ants. They nest in the plants hollow stems and then attack anything that climbs or lights upon their domain, except for the oak blue larvae.

And this is presumably because it has an evolved a defense that tricks the ants into thinking it's okay for it to be there. Yeah, so there's protection within the ants domain, even if ultimately there's no more dangerous place to be than within an antstone. Right, there's protection if you have some kind of evolved defense to sneak through the city walls and say, okay, I'm part of this colony. Now nobody noticed that I'm not an Aunt. Yes, hello,

fellow ants. Now, Aunts have been engineering their own ecosystems for millions of years, right, so there has been a lot of time for these mermica files and these creatures that infest ant colonies and other AUNT controlled environments to very tightly hone their their evolved traits, right that, There's been a lot of time for them to do this. Humans, on the other hand, have only been engineering their own environments for much much less time, just thousands of years.

But nevertheless, our human ant hills seem to be in the early stages of developing Mermica files of our own, except they wouldn't be Mermica files, they would be creatures of the city. As we continue to engineer environments around the concept of the city, more and more forms of wildlife, we're beginning to show marked adaptations and eventually heritable evolved traits for specifically surviving in human urban landscapes. This is urban evolution, and this is gonna be our topic for today.

This is actually going to be the first part of a multipart episode that we will continue to explore just because there's so much interesting stuff to talk about, but it's going to be focused on wild organisms evolving to survive and even thrive within the ecosystems that humans have

engineered for themselves. And we should go ahead and mention that we've been wanting to do this episode for a while, but recently a book came out on this topic and this became one of our major sources for this episode. It's a book but the Dutch evolutionary biologist Minnow Skill Tausend, who is a researcher at the Naturalist Biodiversity Center, which is a museum in Leiden, Netherlands, and the book is called Darwin Comes to Town. It was just published by

Pikador just recently. Yeah, I'll include a link to this book on the landing page for this episode of Stuff to your Mind dot Com. I want to note that the cover illustration is fabulous because you have this this drawing of various animals scaling a zigaratte that it's formed of all these buildings and skyscrapers. Yeah, it's it really captures the spirit of the book. I appreciate a good cover illustration because so many books have bad cover art. Now, yeah,

it seems to be a dying art form. Here's my cry out there. If you're a publisher of science fiction or fantasy or something like that. Stop going with the stop going with the stock art. Get those original illustrated covers back. Those were great. Yes, And I do not want to see another minimalist like mock up of a movie poster or a book cover. I'm done with that. I want I want to a full visual experience. No.

Back to the subject. Okay, So Skill Tolls and actually himself makes this comparison between human cities and ant colonies, and the subsequent comparison between mermenicaphiles and the organisms that have come to thrive in our cities. And I think it's a really good comparison, except one difference is that our cities are actually and much more vast and varied

landscapes than the complex environments that ants create. Right, yeah, I mean you look at something like say New York City, right You have the sort of concrete jungle regions of the city. You have an artificial um wilderness in its center. You have essentially mountains made out of steel and glass that alter the flow of air, that alter the weather itself. You just have so many different elements going on to

warp the natural world into a new form. I tried to make a short list of just some of the ways that cities are fundamental departures from what the natural landscapes around them are like. And I know I didn't capture everything here, but here just the things that occurred to me in our research. One of them is habitation surfaces. Right, not many complex organisms can live on flat concrete without soil or vegetation. That that's not an environment that occur

is all that much on Earth. And when environments kind of like that do occur, there aren't a whole lot of organisms that inhabit them. So much of the plant and animal life in cities is isolated to or based in urban islands of vegetation. So they're gonna be things like parks or small undeveloped areas, or urban trees or yards or gardens or grassy street medians. We look at these spaces in our urban areas as kind of blank, right, Maybe not parks, but a lot of these other things,

like the grassy median between two sides of a highway. Yeah, we think we might think of that as a place that is empty, but really, like that's the only place in your field of vision where there is non human life taking place at any like real degree. We look at those places sort of like the margins of of a page, like that's where nothing's going on. But yeah,

that is in fact like a hot spot. It's a hotbed of life and activity that is surrounded by these dead rivers of asphalt, so many feral cats just whooping it up in there. But there is so much more than that. So okay, that's the obvious habitation surfaces. But then there is climate. Actually, the climate of a city is generally different than the climate of the surrounding area. We've talked before on the podcast about the idea of

the urban heat island effect and urban rain. Uh. The the material properties of cities in the way they absorb and reflect light and retain heat actually affects the temperature and the weather within the city, usually leading to these situations where in the middle of a city it's a lot hotter than the surrounding countryside is on the same day. An obviously huge factor that makes a city different than the surrounding environment is what types of food resources are available,

because it's going to be completely different nutritional profiles. Yeah, outside of the city, a bird has to you know, hunt around for its h its food, but inside the city it can just fly into at home depot and just aisle upon aisle of food awaits it. Now, I wonder if for birds, home depot eventually becomes a sub city within a city, where birds will evolve their own populations within the home depot over that's kind of frightening.

I imagine like large prehistoric carnivorous birds roaming the home depot picking off humans that are a little too little too picky in which soil they're going to purchase for their home garden. Here's another one. You've got very different kinds of threats in human created environments than you do have an unspoiled natural landscapes. You have environmental threats, human threats,

and machine threats. I mean, think about try to put yourself in the mind space of like a fox or a coyote or raccoon or something, and you're living in a place where there are these giant mechanical predators constantly plowing through the city back and forth at high speeds, and they will kill you. But also they don't really seem to chase you, and so it's it's you're not evolved at all to deal with this kind of situation. Yeah, the Frogger game, that is life for an animal in

the city. Yeah, cars as predators. It's a thing that's hard to direct wrap your mind around. If you're a fox, then of course there's a totally different chemical environment than there is in in unspoiled nature. So you've got pollutants. Of course, you've got the byproducts of industry and all that. But then you've got things that people wouldn't even often tend to think of, Like, how about if you're in a northern city, what chemically you might you do to

alter the surfaces of the city during the winter. I'm thinking about spilled hot chocolate for starters. I guess that's a good one. But how about salting the roads? Oh my goodness, I mean, yeah, millions of pounds of salt. You turn it into basically a big salt lick of death exactly. Yeah, so you're you're fundamentally altering the chemical profile of the surfaces that these animals dwell upon, and suddenly all this runoff water that would normally be fresh

water become salt water. And yeah, it's totally strange. Here's another one. The darkness regime, completely different in cities than it is in a place that hasn't been colonized by human beings. That that's a that's a great one. I mean that in roads are situation like light pollution, and in roads, of course are everywhere. The roads crisscross human habitats wherever they occur, and and you know, invite death

for anything that dares to cross it. And then of course we we've all heard accounts of how dangerous artificial lighting can be uh into various natural habitats, including beach habitats for turtles that are returning from the ocean to lay their eggs. Yeah, and of course a big one being for insects. The way light affects insects is crazy.

I mean, there's this thing that's the vacuum cleaner effect that Skill tous And talks about in his book, where you put say a service station out by a dark highway in the middle of nowhere, and it's got lights

on at night. And what this is going to do is act like a vacuum that just sucks in insectual life from the hire surrounding countryside for a period of time until it's killed so many millions of insects that Eventually the density around it just kind of drops off, and then it stops happening for a while, and then you have the city which just has that going on all the time. It's just a center of artificial light

all night. Now, that's by no means all of the ways that cities change the environment from the natural environment, but that that's a handful of them to get you thinking about the ways that these techno beasts that we inhabit that feel very natural and normal to us are are aliens sci fi environments for animals that are designed to live in a meadow or live in the forest

or something like that. And yet at the same time we know for me and Malcolm that life, uh finds a way that's right and find a way it does. And that is what we're going to be focusing on for the rest of the episode today is many of the fascinating ways that urban life affects wildlife and that wildlife apps to it or fails to adapt to it. All Right, we're gonna take a quick break and when we come back, we will dive right into the topic.

Thank alright, we're back. You know, Joe, we live in Atlanta, and certainly especially the portion of Atlanta we reside in is is far from a like stereotypical concrete jungle. We have a lot of green trees around, a lot of these little noman zones of of of of built up weeds and vegetation for things to live in. What are some of your your favorite wild animals that you've encountered. Yeah, Landa actually is sometimes known as the city of Trees,

and I like that about it. I mean, it can be a problem if a tree falls on your house or something, but otherwise it's very nice to have all this urban greenery that we do have. But yeah, as far as urban wildlife goes, I don't know. I mean, there's a lot just in my backyard. Like our our dog Charlie, he loves to chase the squirrels in the backyard. And there was one night not too long ago, when he's not a barker, he'dn't bar much, but we let him out in the backyard one night and suddenly he

started barking, and we're like, what's going on? And we went out to get him and we realized he was in a standoff with an opossum. It's perched up on the fence and not moving. It just was frozen and staring at him and making the face. And so we got him inside and the possum never moved. We looked back out the window like a while later, and it was still in the exact same place, hadn't moved from the spot. And I think about adaptations when I see

stuff like that. So, Okay, you've got an urban opossum and that maybe is getting some tasty trash morsels living in the city like this, but it's also got a deal with dogs and backyards and people and animal catchers and cars and all this stuff that threatens it. And for some reason, it's it's evolved response to this is freeze and make the scary face. Why does it do that and does that usually work or what? What was

that traite evolved as a solution to. You know, the backyard division of things is really interesting because it does create these these little sequestered zones where that are protected, but each one also may contain its own localized predator in the form of a dog or even you know, cats, which I guess are gonna be less restricted by the

fences little enclosures with monsters in them. Yeah, it was very recently It was just last week actually that I heard this rucus bird rucus in the backyard, and I went to check it out because I'm thinking about what's happening in cat that there's a maybe a feral cat back there messing with some birds. I look back there the birds were agitated because a wild turkey was in my backyard. Yeah, so good, I know. It's it's really kind of a holy experienced to see a creature that's

ultimately so large. If you've not seen one there, it's a far different animal than the like the Thanksgiving turkey, but it is it is still a big critter and seeing it hop up there on the fence and then uh disappeared into the next yard was pretty pretty awe inspiring for me. Yeah, my parents actually in Tennessee sometimes

get turkeys in their yard. Well, you know, I don't know about everyone else, but one animal that instantly came to mind from me when thinking of of creatures that thrive in an urban environment is the noble trash panda.

The raccoons. Raccoons, Yeah, they've you know, it makes sense because raccoons, they've thrived in North America for at least two point five million years or at least we know that it's Procyon genus was well established here by that point, with its ancestry reaching back a good through thirty seven million years. But their success is due largely to their flexibility. Oh yeah, there's sort of a jack of all. Yeah, yeah, they they have They have teeth for both the shearing

of meat and also expanded molars for crushing. They also have these incredibly sensitive hands which can be used to manipulate objects and feel without loss of sensitivity for food and chilly stream beds. You know, that makes me wonder Sometimes our listeners have asked this fun question before. It was like, if humans disappeared, what would be the next creature on Earth to like assume the sort of intelligent civilization mantlepiece. And of course you want to say, well,

probably great apes or something. Uh. Some people want to say dolphins or whatever. But you could say, well, I wonder about raccoons. They've got hands that are really kind of a hand alike. They can manipulate objects. That seems significant. Yeah, And I was when I dived a little deeper into this, I was really impressed by just how sensitive their hands are. So I want to read a tidbit here. This is

from Northern Woodlands magazine. Quote. There's a myth that raccoons wash their food, but what they're doing when they wet and rubn object is seeing it. It's thought that water contact increases a raccoon's tactile ability. When a raccoon wets and handles a crayfish, stone worm, or clam, he's gathering information. Nearly two thirds of the sensory data that he's processed comes from cells that interpret various types of touch sensation.

In other words, touches as important a sense as hearing, smell, and sight. I had no idea. That's fascinating, Yeah, I mean it's it's it's I think it's especially hard for you know, any of us with with healthy um sight to really think about that, to think about that sense of touch as being one of the most important ways

that you interact with your surroundings. Well, there's that, but there's also the peripheral sort of mentality that comes along with that, right, the the animal personality that is correlated with the feeling of touch as an exploratory mechanism, because it makes you think that this is a creature that's likely to sample objects in its environment at a high rate. Yeah, it's it's not enough just to peer at it from the shrubs. It's got to get up there. It's got

to handle it and see what's what. So you know what happens when an adaptive creature with marvelous little hands like this ventures into the city, Well, it thrives. And raccoons have been of interest to science for over a century.

Because of this, they flourish in human environments. In nineteen seven, psychologist Lawrence W. Cole and Clark University graduate student Herbert Burnham Davis both independently studied raccoon intelligence in light of this, and they concluded that they were smarter than cats and dogs and were more in the cognitive realm of monkeys.

Now not everyone agrees with that. I should note now, whatever the baseline level of raccoon intelligence, as far as object manipulation and all that goes, there is one thing that has become clear, which is that there's a pretty large variation in the difference between different populations of raccoons and their intelligence at say, uh spatial problem solving, right, the distinction being that of city raccoons and country raccoons,

rural and urban raccoons. Right, it seems like one of those populations has more incentive to get smart about how to mess with objects. That's right. So Susan mcdonne, old comparative psychologist at York University in Toronto. She compared the problem solving abilities of urban and rural raccoons and found that urban raccoons win in both intelligence and ability. Yeah.

I was reading about one of these studies, and apparently it required the raccoon to figure out how to get into a food baited trash can that had its lid held shut with a bungee cord. And apparently in the study I was reading about, none of the rural raccoons could get into the trash can, but about eighty percent of the city raccoons did. Yeah. And in a two thousand and sixteen Nautilus article titled the Intelligent Life of the City Raccoon, Jude Isabella points out the following uh

in this regarding the study quote. For the past few summers, she videotaped rural and urban raccoons toying with containers baited with cat food. While both rural and city raccoons readily approached familiar containers, they dealt differently with unfamiliar ones. Where rural raccoons took a long time to approach novel conta aner's city raccoons would attack them the moment she turned her back. I like that opportunism, and that's great. Yeah, so I got one of the ideas here is city raccoons.

They're they're fast to get in there, they're fearless and approaching a problem. But they also that there they stick with the problem that they're trying to figure out. They'll work at it for an hour or more, trying to figure out how do I get into this, how do I how do I defeat this problem? That just shows perseverance pays off. Yeah, and then this also brings us back just to the idea of a city, like what

does the artificial environment of a city do well? Isabella cites the work of Harvard economist Edward Glacier Uh, the author of Triumph of the City uh and Uh. Glacier argues that cities themselves are machines for learning uh and if raccoons are innately bold and curious uh, then they engage with these puzzles more readily. What's more increasingly complex, latches and and UH and other devices they may be encountering. Quote,

may actually be training raccoons to open them. So the city itself, as we change it, trains the raccoons and sort of changes them. Now, an important thing to consider is that this might be happening at multiple levels of honing the skills of raccoons. Right, you can imagine on in one sense, raccoons are just getting better at solving puzzles within their lives, right, they may to some extent be learning how to adapt to this. But in another extent,

they may be getting better at solving puzzles across generations. Right. The ones that solve more of these puzzles tend to get more food and thus have more offspring. And thus it's possible we're literally seeing an evolution of the city raccoon into a baseline smarter animal, or at least an animal that's better at manipulating these kinds of traps and

foreign objects. Yeah, in a way, it's like the city raccoons are in more of an arms race with their environment, whereas the rural raccoons there's their environment is a bit more static. Now at the same time, I mean, we've already touched on the growing city and uh and one of the ramifications of that is that it diminishes the the rural environments, and that is very evident when it

comes to foxes, especially the foxes of Britain. According to the two thousand seventeen article and The Guardian, Foxes Surge into England's towns and Cities by Charlie cuff Um, the overall number of UK foxes is in decline, but the number of urban foxes has quadrupled over the past twenty years. One study estimates that a hundred and fifty thousand foxes thrive in England one for every three hundred city dwellers.

That's up from thirty three thousand in the nineties. Essentially, what's happening here is that the foxes are losing their rural habitats and they're just finding a lot more food, including garden worms and all those rats and mice, as well as suitable habitats in the urban environment. Skill tous And talks about this in his book, mentioning that some of what drives animals into the city is not just what's available in the city or the fact that the

city now exists where their home used to be. But the depletion of the habitability of the surrounding landscape. This is happening all over the place. Even though cities are these extremely weird, alien places for animals to try to survive in, they tend to be more habitable environments than the waste lands created just outside of cities. I'm reminded

of the witches gingerbread house in the woods. You know, for a couple of kids who are lost in the woods, there's no more dangerous place than going into that gingerbread house. But at the same time, the woods are terrifying and full of inedible things and berries that will poison you if you try and eat them, whereas the witches houses made out of candy. How can you work out a deal with this witch? That's the challenge. But what if the candy is just all of the trash that the

wit threw away because she didn't want to eat herself. Well, so we are on the subject of trash life. Of course, much of what we're talking about with the raccoons is how they are affected by by urban trash and what's trash to us maybe delicious morsels for many scavenging animals, especially if they're not super picky, and they're smart at

manipulating containers and things like that. But I thought we should explore some of the more of the ways that the pervasive presence and endless forms of human garbage, and I mean the garbage produced by humans, not people who are garbage, how that shaped urban animal life. So I've got one, Robert, Do you remember the mcflury hedgehog? I do not remember the mcflury hedgehog. Have you ever had mcflury in in the past. I believe I did have the mcflury or two. Yes, I'm not trying to be

a snob. I can say I've never had one of these things, so I can't speak from experience, but maybe you can help guide me on the mcflury ology. Here. The only thing I remember is that they had a weird top. Yeah, that's that's the thing. So back in the mid nineties, McDonald's fast food restaurant introduced the mcflury, which is it's some kind of ice cream thing, right, God knows what it's like, hamburger flavored ice cream. So now you're now you're just trash talking to mcflury. It

was at least it was sweet. It was sweet flavor does have big MAC sauce in it, No, but it's it's all I remember, is just an overpowering sweetness. Well, so this sweet stuff that was in the mcflurry, it was served out of containers with these weird lids you're

talking about that essentially functioned as a hedgehog trap. So the way it seemed to work is that you'd be eating your mcflurry and then you'd throw the container down on the sidewalk or the parking lot, and then later a hedgehog would come along and want some of that delicious reeking sugar stuff inside the cup. But the aperture in the lid, which would I guess made for spoon access, so you could use a spoon. It was just big enough for hedgehogs and some skunks to stick their heads

inside and slurp up some mcmlty. But then, of course hedgehogs have bines, and the spines are generally oriented to fold backward from the head, so once the hedgehog's head is in the hole, it might not be able to get itself back out of the mcflurry cup. So, on the one hand, this is funny. I've included an image for you to look at. It is funny and very cute and lead too much laughter about little creatures running

around with their heads stuck in cups. But there's a dark side, right, which is that if nobody helped these creatures out, nobody saw them, they would probably die right possibly of starvation, or they might wander into traffic, or they might wander into a body of water and drown. Oh yeah, that is terrifying. It At first it's cute, and then when it it's explained to you, then then it is a very sad affair. But fortunately there was

a good end to it. After years of complaints from organizations like the British Hedgehog Preservation Society in two thousand six, McDonald's eventually changed the design of their lids to make them too small for hedgehogs to get their heads through in the first place. So fortunately that had a good resolution. But that's just one exam ample of the thousands of ways we can't even predict about how the shape or chemistry or nutritional profile or whatever of human refuse will

exploit some fatal flaw in another organism. And also you always have to wonder how if McDonald's had never intervened. This might have shaped the evolution of city dwelling hedgehogs, right, would this cause a selection pressure for hedgehogs that were better at getting their heads out of small holes, or for hedgehogs with big heads that would never get through the hole to begin with, or for hedgehogs that didn't like the smell of dairy products and wouldn't be interested

in ice cream. So let's dig through more trash, Robert, you're ready to dig through more to do it? What else is in there that's that's worth eaten? How about beatles and bottles? Have you ever read this story before, Robert, I've read Fox in Socks where there's a much discussion of of beatle battles inside of a bottle. No, no, no, this is beatle. This is not a battle. This is a beatle something else outside of a bottle. So I want to take you to Australia to meet the Julo

Dimorpha bake Welly, which is the Australian jewel beetle. It's a type of beetle from the boot breasted family found throughout a lot of parts of Australia, and so in nineteen eighty three, there were a couple of biologists named Darryl Quinn and David Rince, and they published some interesting findings about human trash and its local effects on wildlife in the Journal of austral Entomology. So here's the story.

Earlier that year, in nineteen eighty three, the authors were wandering out beside a highway near a town called Donra in Western Australia, and they noticed something weird. A male jewel beetle perched on top of a piece of litter, which was a discarded brown beer bottle. Okay, well, that in and in and of itself is not that strange. Uh. Then they got closer and they looked see what's going on here, and they realized the beetle was trying to

mate with the beer bottle. The authors looked around and they found two more beer bottles of the same type, both of which had male bake wellies trying to mate with them, and the males were either on the side of the bottle or quote mounted on top with quote averted genitalia. And I've got a picture here of what the beetles look like with averted genitalia. Okay, I'm seeing it now. I don't know if you have any comments

on that, um I do. It does convey the sense that this, uh, this insect is trying to mate with the bottle. That's quite averted, So what's going on here? Well, The authors noted that bake Welly is a species in which males can fly and the females are ground dwelling, and the color and texture of these beer bottles in many ways resembled a giant female of this beetle species.

The author's right quote the shiny brown color of the glass is similar to the shiny yellow brown electra of J. Bake Welly and quote rows of regularly spaced small tubercles around the base of the bottles reflect light in a similar way to the punctations on the electra of the beetle. So the brown beer bottles referred to as stubbies in

Australia at the time. We're proving very efficient at setting off mating behaviors in male beetles, and almost alarmingly so, because when the author's picked up the bottles, the beatles would not leave them unless physically removed. And then the authors also performed an informal experiment where they placed four stubbies these beer bottles on the ground and watched to see what happened, and within thirty minutes, two of the four bottles had male beetles trying to mate with them.

And it gets worse. I want to read a quote from their paper. Quote. In one of the observations, a male at the side of the bottle was being attacked by a number of ants which were biting at the soft portions of his averted genitalia. A dead male covered in ants was located a few centimeters away from this same bottle. So these things are literally dying to mate with glass bottles because just going off of their genetic programming like this is their purpose. I have come here

to mate with this. This is glorious and large of females, and I must do so even as answer tearing me apart exactly right, ants maybe chewing off my genitals, But it is worth it because this bottle sets off all of my internal signals for amazing attractiveness in a female of my species. So there is another fortunate ending from the human perspective. I reade a report on NPR that the bottle designers became aware of this and eventually they changed the bottle design to remove the small bumps on

the glass. After they did that, the male beetles stopped caring about them. Oh that's good. But once again, you can imagine what would have happened if nobody noticed this and the bottle makers never changed their methods. Will never know, but one possibility is these beetles could have become endangered or gone extinct, with all the healthy males refusing to mate with actual females because they preferred glass bottles. These bottles were better looking than the real members of the species.

But in other possibilities, the species would have evolved to favor different sexual preference genes and males. Right that males would be not attracted to whatever features set off the extreme bottle desire, but to something else, maybe sent or something like that. And I mean again, just the crazy thing about this is that it's not like they were setting around trying to come up with a bottle design that would throw off beetle mating in the immediate area.

This was just pure accident, but it could have had disastrous consequences for the species. All this stuff is pure accident. Now I want to explore an accident that went a different way where animals have been found to be adapting in a positive way to harmful trash being thrown into their environment. Uh. Do you ever have that friend Robert who thought it was cool to flick cigarette butts out

into the world when they're done smoking. You know, they're like the system man, they finished there and just flicked the butt. I have not, but I will still occasionally see somebody at like a stoplight that's doing that, and I judged them rather harshly. Yeah, it's not cool to do. Don't don't litter the world with your cigarette butts. But it actually that was not a pun, by the way. Uh,

there's an interest follow up to this. So. Montserrat Suarez Rodriguez is an ecologist at the National Autonomous University of Mexico in Mexico City, and she and her colleagues Isabel Lopez Rule and Constantino Marcius Garcia published some fascinating research in Biology Letters in and they started by pointing out something really interesting about the birds of Mexico City. The

birds were putting discarded cigarette butts in their nests. Okay, well that that in and on itself doesn't sound crazy, because if they're if there are a lot of these around. If cigarette butts are more forthcoming than twigs, then why not put them in your nest? Right? Yeah, they're fiber, right, So if the cities are full of littered cigarette butts, maybe the urban birds will just use whatever kind of fiber is around to be part of the nest that.

You know, there's some cellulose here, I'll put it in the structure of the nest. But these researchers performed experiments and they found something pretty amazing. They looked at the nests of house sparrows, which are passer domestica us and house finches, which are Carpodacus and mexicanus, and they found that the more cigarette butts a nest contained, the fewer

parasitic mites could be found in the nest. Now why would that be, Well, cigarette butts contain a cellulose filter through which the smoke passes when you smoke a cigarette, right, and this filter traps all kinds of compounds from the smoke, including nicotine, the stimulant drug in the tobacco products. So why do tobacco plants contain nicotine in the first place. It's because it is a poison designed to deter herbivorous animals from eating the plants, including insects, and it's even

been used by humans directly as an insecticide. Oh, so this is a for the birds and naturally occurring insecticide in their artificial city environment. Exactly, the birds have parasitic arthropods that attack them in their nests, but if they line their nests with insecticide traps found among the trap shin gutters of the city, they can repel these parasites. And the researchers confirmed this by setting up traps to

attract parasites lined with two types of cigarette butts. They had smoked butts and unsmoked butts, and the parasites were much more deterred from the nest that had the smoked butts in them. Now, why would that be. The smoked butts contained the nicotine because the smoke had come through them, while the unsmoked butts didn't contain any they were just the cellulose. So the researchers determined it was not just

the fiber, really was the nicotine. And now, at the same time, that's an ingenious adaptation to the available materials of a city. But we also shouldn't conclude that this is always going to be good for the birds, because exposure, of course, could have negative side effects that haven't been identified yet. We all know what some of the negative side effects of exposure to tobacco products can be. But still they've they've essentially made a protective chemical weapon out

of these discarded cigarette butts. Now here's another thing about the physical environment of cities that most of us probably wouldn't even stop to think about. But there is an extremely simple diff friends in the kinds of physical surfaces one encounters more often in the city versus the country. Right, what kind of animal is actually evolved to live on hard, flat, relatively smooth surfaces with no vegetation cover that you can't

dig down into? And that sounds like a nightmare? Right, Yeah? Like, what kind of creatures do would you typically find scurrying about on rocks and other flat surfaces? I mean not that many. I mean you some live on rocks, but at least then you'd have vegetation nearby, or you could retreat down into cracks between the rocks. The sort of flat, unbreakable surfaces of the city are, and especially the smooth ones are just not great for many animals, but nevertheless,

animals adapt, life finds a way. So another study I want to mention is that a team led by Kristen Winchell of the University of Massachusetts, Boston examined males of the animal lizard which is Enolis christ to tell Us from a couple of cities in Puerto Rico and compared them to males of the same species from adjacent four

wrists And was there any biological difference? You bet. They actually published their results in the journal Evolution in sixteen, and what they reported was that the city lizards had both longer legs and they had more lamela, which are these structures on the toes on the undersides of the feet that helped the toes stick to surfaces, especially smooth surfaces.

So these traits were probably helping the lizards, helping these animal lizards evolved to be able to climb smooth walls and stay attached to these smooth, slippery surfaces, even vertically aligned ones. Yeah, these these kind of like essentially like hyper surfaces. Is that you're not going to find something that is that is that flat, uh and in featureless

that that vertical in the natural environment. Yeah, and so to test whether this was an actual inherited trait, they also raised lizards from stock captured in the city and from stock captured in the forest, and they raised them both in the lab just to make sure it was a true genetic difference and not some weird way the lizards were able to change their bodies during life, and it turned out it was a true heritable difference. The city lizards hatched wall climbers with these more lamlay and

the longer legs, and the forest lizards did not. And you can imagine that so many city species are evolving along these lines with small changes in their body just to get a better grip on the surfaces of human made environments. Right, Yeah, it makes perfect sense. Like this is the this is the geography you're presented with. Now, while we're on the subject of crawling reptiles, I want

to know something about city dwelling animals. Is it true that there are colonies of alligators living in the New York sewers? Ah, Now, this is a fun, fun topic. Sometimes they are they're they're reported to be blind like albino alligators living Yeah, in like thick packs in the depths of say the New York sewer system. Is this ever addressed in one of the Blade movies. I don't think so. Maybe unless they made passing reference to it.

I'd know it shows up in Teenage Mutant Ninja Turtles, So it would have been a great set piece to have, like Blade Battle, like an albino crocodile vampire that lives in the sewers. Well, we have at least one film. There's a nineteen eighties alligator. Do you remember this one? I've never seen it. I should have. I don't know why I haven't seen it. Oh man, I saw it as a kid. It was It was a lot of fun.

It started Robert Forster, and it takes place in Chicago, though not in New York City, which is a shame considering what I'm about to lay on everybody, Well, tell me, is it real? Okay? It? Well, it's not real. I think if you were near a New York sewer right now, do not worry about the blind alligators climbing up after you.

I looked at a nineteen seventy nine paper, Alligators in the Sewers, A journalistic origin by Lauren Coleman, published in the Journal of American folklore, and um, she this is interesting.

She points to Thomas Pension, uh, the famed American author of Gravity's Rainbow, as someone who did not He did not originate the tale, but he helped to propagate it, and propel it through his debut nine novel V in which there's this, uh, this this brief discussion of you know, the classic trope baby alligators that are acquired at a carnivore fair or on a trip to Florida. You come back to New York, they start getting bigger. So what happens? They get flushed down the toilet or thrown out and

then they wind up in the sewer. That sounds like a cruel thing to do to a baby alligator, I agree, But it it's this, you know, this idea that, oh, well, they wind up here by accident, and then they wind up down there, and then they thrive quote down there. God knew how many there were. Some had turned cannibal because in their neighborhood the rats had all been eaten or had fled in terror, thanks Thomas Pension. But Coleman

digs deeper than than this. So various authors and even herpetologist she found, referred to the urban legend, but they cited it as such. They were not saying this is true. They were saying, hey, this is crazy story some people tell um claiming, you know, they grow fat on New York sewer rats, they and or they grow pale and

blind in the depths. But then she explored more than seventy reports of just alligator sightings in general in Northern American climates, such as an eight account of a frozen gator that's supposedly watched up on the banks of the Rock River in Wisconsin. But she found just one single account of a sewer gator that was at the time actually reported as fact. And she admits that this may

have never taken place. It could be, you know, a fraudulent story, but the matter of fact reporting style and the fact that this was a very established paper may have caused the story to simply explode. Wait what paper was it? The New York Times, February five. You can find this full um this full article online either uh in the New York Times are archives which I believe you need a membership to access. But then other people

have have have reproduced it elsewhere on the web. This is the title alligator found an uptown sewer youth shoveling snow and man hoole see the animal churning and the icy waters snare it and drag it out reptile, slain by rescuers when it gets vicious. Whence it came is mystery, So I'm gonna let everyone else go read this on their own. I'll include a link to it on the landing page for this episode of Stuff Toblow your Mind

dot Com. But essentially the idea is, uh, the they discover this sewer gator and they're frightened by it, and then they drag it up and onto the onto the snow, and then beat it to death with snow shovels. Yea, why, it's just what you do, I guess when you're frightened of a of a large creature. But then it But again, I want to stress this doesn't mean this actually happened. Yes, it made it into the New York Times, but when you start looking at the evidence that you still have

to doubt that this really occurred. Okay, Well, what about sewer gators in general? I mean, is there any evidence that there might be gators living in the sewers underneath some cities? Well, I looked into this a little bit. So for one question that immediately came to mind is, Okay, New York is u is a bit too far north for alligators to really have a chance. But are alligators

living in sewers in say Florida? And uh and yeah, you you do see reports of gators winding up in Florida storm drains or sewers and many of and this is because many of these waste outlets back out into the swamps. But New York sewers not really outside of just pure you know, urban legend. This one story and also an account from two thousand ten in which a baby gator was found in a Chinatown sewer, there's not

a lot to go on. And with that baby gator, it's I'm it seems like it was probably just a case of somebody through this this creature out into the sewer and then it was found. This is not the same as say, adult sewer born alligators popping up in Times Square. And then I should also mentioned that snopes dot com has an article on this, and they point to the writings of nature writer Diane Ackerman. She points out that the gators would only be able to survive

for a few months at the most. In New York sewers, I would guess this would probably be the summer months, right, right, because the big thing is the temperature. They're gonna need temperatures between eighty seven and ninety degrees fahrenheit. And we're talking about them living in the sewer. Uh, They're they're gonna be surrounded by Salmonella E coli, shigela, other sewer microbes that they're just not going to be able to live with those. They're going to die in there. A

sewer is just not a suitable habitat for an alligator. Yeah, And I think this does draw attention to the fact that while we do see many animals uh coming up with fascinating adaptations and even evolving to be better fits for city life, not all animals are good candidates for this, and certainly not all animals are good candidates for this

in all cities. Yeah, because with the alligator, for instance, in in Florida, Yes, during the colder months, a storm drain environment can be actually an excellent place for a gator to hold up. All right, on that note, we're going to take another quick break and then we'll be right back all right, We're back all right. Now we've been talking about the myth of the New York sewer gators, which does not turn out to be true, and this has highlighted some of the ways in which not all

animals are well suited to all city environments. Some are much more suited to it than others. One animal that has proven extremely well suited to city environments that is a larger predator, kind of like an alligator, but very different type, is the coyote. Yeah. And I've always found this interesting because when I've lived in very rural environments and when I've i've lived in urban environments, they're all essentially all I encounter are mostly tales of the coyote.

It's such a secretive and stealthy animal that it's more of a It's it's almost supernatural, this this beast that is there, but you're only aware of it through its childlike noises from the kud zoo under dark, just you know, reaching out after you. Yeah, I mean, it's it's haunting. That's this beautiful image. I don't usually think of coyotes

that way. I guess they're so common in cities. Now we've started they've started to lose some of their wildlife magic, and we start to think of them as like, oh, that's like a city rat or something, you know. But no, it's a It's a coyote. This is a large, candid predator. I mean, this is an interesting thing, the fact that

they're colonizing our cities so much so. I found an interesting Ohio State University news report on the work of the os U wildlife ecologist stand Girt, who has been studying urban coyotes, and some interesting facts and observations from Girt's research. One is that coyotes have colonized pretty much every big city in the United States. In somebody even snapped a picture of a coyote standing on the roof of a bar in Queens. Wow, how did it get there?

I don't know they I think they think maybe it got out from a window of a building nearby or something like that. In Queens, there's a coyote on the roof of a bar. And this actually just isn't all that weird as weird as it seems, because coyotes are everywhere in our cities. Gert has observed coyotes adapting to city traffic, literally pausing at the edge of the street, looking at the direction that traffic comes from, and checking

for oncoming traffic. Because in an urban environment we've already talked about the idea of cars as predators. The number one cause for death for a coyote in a city is getting hit by a car. But those risks are paired with big rewards because Girt's research has found that an average litter size for an urban coyote is nine pups, which is bigger than the average litter size in rural areas. And this means city coyotes are fattening up on abundant resources.

And this is possible because coyotes can make you of all kinds of resources their omnivores. They'll lead almost anything, and these are the kinds of organisms that tend to do well in cities. Now, on the other hand, people have started to see them very much as an urban nuisance. I even found a New York Times article about the trend of urban hunters culling city coyote populations. Have you

read about I have not heard about this. I've heard about, you know, rat hunters, obviously, but this is the first effort about the coyote hunters. Yeah, so because of this kind of action and the fact that we will never seem to get rid of all of them, I wonder if we may actually be driving a selection regime to evolve urban coyotes that are guess what, good at hiding

from humans. And there's a cool example of this that's actually already been reported in places like National Geographic so uh, to quote from that GEO article on it, quote in downtown Chicago, one GPS collared coyote pair raised a litter of five healthy pups inside a secret concrete den in the parking lot of Soldier Field Stadium, home of the Chicago bears a high traffic environment, but the signals to me the emergence of of invisibility traits in these creatures.

You know, they find those places where no one will look for them. Okay, one last animal to look at. There are millions of ways we could look at mice, but there is one way that I think is going to be particularly interesting. So one of the ways we don't often think about the effects of the techno ecosystem of the city is that it creates urban islands. And this could be counterintuitive to us, because to us, a city is actually one of the easiest places in the

world to get around. Right, there's no rocky terrain, there's no forest blocking the way of getting through things. A city is the place where you can go to somewhere, right, Yeah, I mean you hear about Oh, this is a very walkable city. You can just get out and walk wherever you want. You don't have to cross a river, scale a mountain. It's just all there. But for many animals,

a city is exactly the opposite. So his book Skill Tousand points out many ways that cities start to recreate the principles of island biogeography by allowing small patches of habitable environment that are separated from one another by all kinds of virtually impassable barriers, freeways or even small roads. For some animals, breaks and vegetation cover. There are all

kinds of barriers we wouldn't even think of. So Skill Tousand mentions a case of something kind of like island evolution from within New York City, specifically the work of a zoologist named Jason Munshi south of for Fordham University, who studies the way that different isolated populations of mice have evolved for specializations for different parks of New York

City now Munchie South. Research is focused on the white footed mouse or Paramiscus leucopus, and this mouse inhabited the meadows, swamps, and forests to the New York City area long before humans ever settled there, so it's not the kind of

mouse that follows human settlements everywhere. It's a local has clung onto survival in the city that rose up around it, and so originally this population of white footed mice would have been a single combined population with continuous interbreeding throughout. But the populations that have survived up until now in New York are isolated from one another on the islands of New York's parks. So there's a population in Central Park and one in Prospect Park, and more in smaller

parks around the city. And the mice can do pretty well in these parks because most of the park's actually aren't big enough to support natural predators like owls or foxes. But the different park populations don't tend to interbreed with one another very much, which means they're free to evolve independently in different directions, whether through local natural selection or just through genetic drift. Yeah, because how's a mouse going to get from say, Washington Square Park all the way

to Central Park. Are they're gonna They're gonna take the train. Now, I mean some some rodents will be better at traversing the city in that way than others. These mice are very shy. They want vegetation cover. They don't want to come out from under the plants they live beneath. So unless there was like a land bridge of parks between the two, right, yeah, they're probably not going to leave

their island. Now. It's not that mixing never happens, but it's very rare, and rare enough that these populations do have evolved to become genetically distinct. Munchie South and colleagues have. They've been tracking the evolution of these different park populations by trapping mice from each of the parks and performing cross reference to DNA tests. Now, gene pool fragmentation like this is generally considered bad for the health of a

species in a long run. This is one of the reasons you see these wildlife corridors, you know, that are so important. It's because they help creatures from one side of a freeway come to the other side so they can mate and increase the gene flow across the two populations. But nevertheless, the fragmented populations of white footed mice seem to be doing pretty well, and they've adapted more and

more to their local conditions in the parks where they live. Now, you might think, how could the adaptation pressures of one city park be all that different from the pressures of another park or another place. I mean, there's some interesting results. So here here are some adaptations they found that were

specific to Central Park mice. The Central Park mice had a variation in the a k R seven gene, which is involved in neutralizing a flat toxin, which is a toxic compound produced by some molds, as Skill tells and points out molds that grow on seeds and nuts. Interesting. So the obvious implication is that the Central Park mice are more exposed to this kind of toxin, probably in

the foods that they eat. Another one involved in diet a variation on the f A d S one gene, which is involved in the metabolism of high fat diets. This is probably a trash situation, yeah, kind of not not hard to see what's going on there. But then there are other mutations found in the city park mice having to do with diet, metabolism, exposure to pollutants, and importantly immune function because, as Munchie South says, quote, very

easy to spread disease when you're in a small population. Interesting. I love this they are since they're evolving to live on a diet of one dollar pizza slices. Right, Yes, as are many New Yorkers, And so, I mean fair is fair, But New Yorkers at least you know, they've got more ways to get around, right. These mice live on an island, even in the middle of a city. It is an island to them. They really can't leave,

so they deal with what imports arrive. That this is going to be going to think about the next time you're walking through a city park. Yeah, I mean, it's kind of crazy to imagine that the types of trash usually littered in one park versus the types of trash usually littered in another park. If they're different enough types of trash, this could literally be shaping the evolution of the creatures that live in those parks. Oh wow, so

is the human population like that? The details of a human population change around a certain park, it could have a drafting even disastrous effect on the mice that reside there. Yes, food trends come and go a nearby restaurants and stuff like that. It's crazy. Yeah, they depend on the avocado toast and then what happens when that goes away? Right? Oh yeah, we we we went all in on evolving to be avocado toast eaters and now you're into what

grapefruit rice? And I don't want that. Well, I think we should wrap up today's episode with just one final look at some general trends in urban evolution that have been observed across many studies and and of course be reminded that we're going to come back and explore more examples of urban evolution and adaptation in the next episode here. But to sum up today, uh, actually, Jason Munchie South, who were we were just talking about, is one of the authors of a paper we're about to look at.

The other author was Mark T. J. Johnson, and this was a paper called Evolution of Life in Urban Environments published in Science in and this is a huge review of research on urban evolution, observed general trends and what's been discovered in the literature so far. To discuss one example, uh, the general trend they've identified as quote, cities elevate the strength of random genetic drift meaning stochastic or random changes in alleal frequencies, and restrict gene flow meaning the movement

of alleles between populations due to dispersal and mating. And so this leads to a loss in genetic diversity within populations and increasing difference between populations, just like we were talking about with the mice, right. Smaller number of studies they found indicate that urban pollution can increase mutation rates in urban dwelling animals, which might actually speed up evolution, right,

if you've got more mutations going on. But then also when it comes to natural selection, cities tend to present different selection pressures the natural environments, and so they say, quote, adaptations typically evolve in response to pesticide use, pollution, local climate, or the physic coal structure of cities. And that's not even counting um canisers of mutagen that are thrown into the sewer affect the local turtle population. I mean, you

can't even factor that in. That's just anomally. But one more trade I think would be worth mentioning is something that Skill to House and mentions in his book as adaptive to many species in cities, and it's what would be known as neophilia, or an attraction to strange or familiar or unfamiliar objects. Like if you're an animal, neophilia

obviously cuts both ways. It's a gamble. If you approach a strange, unfamiliar object, it could turn out to yield big rewards for you might have some good tasty morsels in there, or it could turn out to injure or kill you. Nature probably pays many animals to be conservative and avoid strange stimuli, better not to risk it. Right, But in the city animals can get big rewards by approaching a KFC bucket or an ice cream carton or other objects that would not they would not have natural

instincts for or any previous experience with. So there could be cases in the cities where neophilia is positively selected for in a strong way, maybe breeding more bold, more curious animals. Well, I this brings me back to the raccoons. You know, the idea that the raccoon is bold in its uh, it's experimentation with some sort of a puzzle before it, you know, such as a KFC bucket. I mean a KFC buckets probably nothing to a raccoon. I'm sure they're well, they are well acquainted with the with

the bucket of KFC at this point. Excuse me, Mr Lamb, we know about those. Um yeah, well, I guess maybe that should be it for today, right, and then we can explore more when we come back. We haven't even gotten deep into one of the most fascinating areas of urban evolution, which is birds. Yes, and then there's the whole we we talked a little bit about light earlier, but light pollution is another area with some very surprising adaptations that are occurring. We will explore all of those

fascinating avenues the next time. And uh hey, while you're waiting for those, uh those new explorations, head on over to stuff to Blow your Mind dot com. That is the mothership. That's where you'll find this episode, all other episodes, including our episode on the London Underground mosquito, which is a fascinating look at a particular species that has adapted to an artificial human environment, that of the London Underground

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Tarry Harrison. If you would like to get in touch with us directly to let us know feedback on this episode or any other episode, to suggest a future topic, or just to say hi as always, you can email us at blow the Mind at how stuff works dot com For more on this and thousands of other topics. Is it how stuff works dot com