Pulling Power
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When I was a kid, my family moved to New York City from Columbia. We moved into my grandfather's apartment in Jackson Heights, Queens. And he owned a Colombian bakery. Every morning, he'd get up at like 4 or 5 while the whole city was still asleep, go downstairs into this room, and the walls were just lined with ovens. And he would start making bread.

There's a whole variety. There's buñuelo, which is crispy and fried, pan de bono, fluffy, chewy inside, and one of my favorites, pan alineado.

This is like a delicious loaf of bread. Crisp on the outside, and then there's just this river of cheese baked right through the middle of it. Completely irresistible combination. It's perfection. And my god, the smell of freshly baked Colombian bread, whew, it's instinctive. Like, I smell it, and I have to go get some. I'm like pulled backwards, zip, right into the store.

I cannot let that opportunity pass me by. And that sense of being pulled towards something, it's such a strong feeling. But you know, it doesn't just happen with our favorite food, right? In life, there's a lot of things that are actually pulling us, pulling animals in all sorts of directions. Whether or not we understand what's going on at first, we've all been subject to that mysterious pulling power. I'm Sebastian Echeverri. And I'm Rotundo Shackleton. And this is the BBC Earth Podcast.

Ryan Reynolds here from Mint Mobile. With the price of just about everything going up during inflation, we thought we'd bring our prices down.

So to help us, we brought in a reverse auctioneer, which is apparently a thing.

In this episode, we're talking about pulling power. We've got a coral reef with its own speaker system, some very confused ants, and one of the most famous soundscapes of the British countryside. Sebastian, I have got this image of you walking down the streets in Queens, New York, and

and then smelling one of these Colombian cheese rolls, pan alineado. And you've got this thin cartoon cloud going straight from the bakery to your nostrils, pulling you in like a tractor beam. Yeah, that's basically exactly what's going on. Like, yeah, we don't live in like cartoon universe. So you can't actually see the smell, but you can like,

almost see it, it's that strong. That like pulling power of delicious cheesy snacks is for real. Ugh, and the cheese and bread combo, you cannot go wrong with that. It's a classic. It's a classic for a reason. And food smells in the wind are obviously a strong pulling power in the natural world too. A carcass can draw scavengers from all

all over. Right. And it's not just on the wind. In the ocean, in the water, I feel like a lot of us have heard about how some species of sharks can detect even just a few drops of blood from a huge distance. Exactly. There's also this pull towards members of

your community. As you know, Sebastian, I study elephants and they need to stay together somehow when they're out in the jungle or on the savannah. Oh yeah, I can imagine those are really dangerous places to be out there on your own. Totally. And, you know, like with social animals like elephants, they roam around for hundreds of miles across areas that do have very real threats. So there's safety in numbers. And, you know,

Home is where the herd is. Home is where the herd is. Is that a Rutendo original? I love it. It will be an original once I make it a sticker and put it on the back of my car. Okay.

But the thing that makes them special is the way that they communicate with their herd members when they're so far away. So when elephants are apart from each other, you know, over the course of the day, they use very low frequency rumbling that goes through the ground and travels underground. And these infrasonic rumblings can travel for,

hundreds of miles. Wow. These signals are actually picked up through their feet, not their ears. And they're

And they know where their clan members or family members are in any given space just by sensing these infrasonic vibrations. Now, that works really great if you're like a huge elephant that can make these like deep rumbles, right? But there are plenty of other animals that are trying to find themselves out in dangerous environments. Like, what if you're tiny and the world is giant? Like,

Okay, say take a desert ant for example. You're finding your way back to the safety of your colony. You're gonna need some really clever tricks. Rotendo, you can take it from here. In Greece, below the earth, desert ants are going about their daily chores. For the first four weeks of their life, they stay busy, buried within the confines of their nest, keeping the place tidy, serving their queen, all in total darkness.

Eventually, life above ground becomes ever more enticing. German scientist and self-confessed ant-thusiast Dr. Pauline Fleischmann told me: They start to dig tunnels, and that might be the first time of their life when they are exposed to light.

then they will start to become foragers. I can imagine it's a pretty dramatic experience for the ants. You know, when you're going from a dark room and you step outside into the midday sun, you're like blinded for a second.

For sure. It's a shock to the system, right? Our ants are out of the darkness and into the day with all the prospects and dangers that it brings. And then they probably survive about a week. Oh, wow. So it's quite short. Poor ants. I know. But at least their new role is quite an adventure, albeit a tentative one. They're out there.

Although these ants are apprentices in their new way of life, so they do research trips. Pauline calls them training walks, making sure they can always find their way home. Yeah, so it's a well-structured behavior in which they do not search for food, but instead they acquire all information they need for navigation as foragers later on. The ants circle around the nest entrance.

Yeah, so this particular emphasis on a long gaze towards their nest at the end is almost like they're taking a snapshot to help them memorize the way home. Okay, no wait, I know what this is.

When I park in a garage, I've learned through experience. Note the landmarks, stare at my car, and make sure I do not lose it. It's a very important thing to learn. I'm glad me and the ants are on the same level here. That is so much better than me, Sebastian, because I have definitely had times when I've waited until closing time and all the cars have left the parking garage to find mine. But yeah, that's exactly what it is.

So Pauline and her team discovered that this training routine held some surprising revelations. It was actually our newbie foragers tuning into and seeking direction from the Earth's magnetic field. Wait, so they're not actually looking at stuff. They're tuning into like an internal like GPS system? Yeah, that's exactly it.

What actually made you suspect that the Earth's magnetic field had a role to play in their navigation? Actually, we did not expect that at all, but it was a huge surprise. We assumed that the new ants would also rely on the position of the Sun to navigate at the beginning. But yeah, it turned out that they instead rely on the magnetic field.

And to test this, we built a simple electromagnetic spiral and put it around the nest entrance to mix up the geomagnetic field. All right, I'm going to have to stop you right there. What is an electromagnetic spiral? This is a special type of electromagnet, which is a magnet created from an electric coil. And this type of electromagnet can be set up so that it completely surrounds the ant's nest.

So normally while the ants are on these research trips, they turn and face the nest to remind themselves where home is. But once Pauline's team switched on the electromagnet, suddenly the ants were facing the wrong way. Their sense of direction had been scrambled. When they turn around, they don't gaze back towards the nest entrance, but somewhere it's a clearly observable behavior. You can see it by eye.

So it was the first time and the first proof that at the beginning of their foraging career, the ants use indeed the magnetic field. So if the ants were navigating by what they could see, like a tree or the sun, they would still be able to find their way home, right? Because nothing in their environment had changed? Exactly. The only thing that has changed is the magnetic field. And the researchers tested this by changing the magnetic field in quite precise ways. We

We can really see that if we rotate the Earth's magnetic field by, let's say, 180 degrees, we also rotate the gaze directions of the ants by 180 degrees. The ants are really small. How are they able to be...

sensitive or detect the Earth's magnetic field anyways they're so tiny how are they able to do that? Unfortunately I don't have an answer to this question but we don't know an answer to this question for any species. I work with elephants that are big massive mammals but you work with ants who are so small but

but so complex. Have they always been your passion? The more I get to know about them, the more I want to work with them because every time you learn a new fact about their behavior and their appearance, you have more questions. So I think there are still many open questions left and I'm eager to answer them. They have many secrets behind

I'm right there with Dr. Fleischman. I want to know those ant secrets. Because it seems like animals' abilities to have these senses that kind of go on beyond past what we think we can do, there's always more to be found. There was a point when people had no idea how sea animals, like,

found out where they were in the ocean. But it turns out that after doing a lot of cool experiments, a lot of these animals are also using the magnetic field to figure out, you know, which way is north, which way is south, have a little compass. And birds do it too.

And actually, Sebastian, Dr. Fleischman's research reminds me of a film. Have you ever watched The Legends of the Guardians, The Owls of Gahool? No, I have not. It's an animated film about owl guardians. And the evil owls in the film, the bad guys, actually collect little flecks of magnets and

that then scramble the hero owls, the guardians, that scramble their ability to navigate. So when they're in their big battle, the bad guys have this big ball of magnets that then obviously scramble the environment. And this is what it reminded me of. I guess the big difference between us and these evil owls are that at the end of the experiment, Dr. Fleischman turned off

the coil, the spiral, and the ants were totally fine. They just went back to doing their old ant things. But the idea of it, the manipulation, the trickery that's pushing and pulling animals to do certain things, that happens all over the world all the time. For example, orchids are a good one. These beautiful flowers with ornate designs, and they all look different,

But one group of orchids has evolved to look like a female bee. And so the males, which are on their lifelong quest to find a mate, are tricked, completely fooled by this flower. And they will fly up to it and try to mate with it.

and in the process get covered in the pollen of the orchid and then when they eventually give up and fly off and end up finding another orchid they pass on the pollen and thus the orchid gets to mate through this bee.

that it's completely bamboozled. I totally feel bad for the male bees because I kind of like want to be like, hey, you're being catfished, but obviously it's for a good reason. This is part of the circle of life. Unfortunately, the male bee is tricked, but it's only momentarily, right? And science has learned a lot from this too. Manipulating attraction can pull animals off course, but it can also potentially save the world.

One of my favorite examples I've heard about recently is how some British scientists, including Steve Simpson from the University of Bristol, are using the same kind of technique to coax dying coral reefs back to health. Scuba diving on a coral reef is one of the most fantastic experiences you can have in nature.

It's like visiting the busiest marketplace where you've got huge amounts of colour, of movement, lots of different animals interacting with each other, sometimes huge schools of fish all the same colour swimming in unison, occasionally really exciting bigger predators like sharks or even dolphins swimming around on the reef. But it's only really recently that we've started to listen to the coral reefs as well.

And sometimes that means trying to do it without scuba diving equipment that can often be the dominant sound you hear when you're diving. So if you drop a hydrophone, an underwater microphone onto a reef, the whole thing comes to life in an entirely new dimension. You start to hear, first of all, this constant background crackling sound from snapping shrimp. And on top of that sound, which kind of sounds like bacon sizzling in a pan or rain beating down on a roof,

You've got all of the different fish species that can vocalise, and that's hundreds, possibly thousands of species that all have their own types of sounds. They can cause pops or pulses, bub-bub-bub-bub-bub sort of sounds, whooping sounds, whoop-whoop-whoop-whoop, and then grunting, deeper, rasping sounds. Parrotfish scraping away on the reef, and there are croaking sounds.

Some can sound quite tonal, almost like they're singing. So when you put all of that together, you've got a carnival of life. And it sounds like you've got a very busy, fairly uncoordinated orchestra, all desperate to make their sound heard. VIRGINIA

And so when we listen to reefs, we realise that every reef, based on the animals living there, has a unique signature. And these unique soundscapes really help us to understand the biodiversity of different types of coral reefs.

But now we're realizing that these sounds aren't just a good source of information for biologists like me. Increasingly, we're realizing the sound is critical for the animals that live on the reef as a source of information for orientation and for navigation. So almost all animals that we see living on coral reefs actually have two parts to their life cycle.

So whether it's crabs or lobsters or fish or even corals, they produce eggs in the breeding seasons and when fertilised those eggs then tend to be very buoyant, they float up to the surface and the currents take those eggs out to sea where they hatch and it's there that the larvae of the animals then develop.

So what's amazing is that every kind of animal we've looked at responds to sound and uses this as a way of choosing where to live. Lobsters and crabs and oysters and clams are all able to detect the sound, move towards the direction of the sound and use it as a way of settling down onto a reef. A few years ago we had all our acoustic equipment in Curacao, an island in the southern Caribbean.

where, by chance, another team were separately looking at coral spawning. They were out each night collecting larval corals, which are really just tiny pinhead-sized balls. They look almost like fuzzy tennis balls as they swim around. And they asked whether they could borrow our acoustic equipment to test whether their coral larvae also move towards the sound.

Naively I said there's no chance that this could be possible. These coral larvae don't have a brain, they don't have a central nervous system. But sure enough, as soon as we started playing sound through the speakers, these coral larvae started moving towards the direction of the sound. Somehow they could detect it and it changed their swimming behaviour.

When you look at a coral larva, it's hard to imagine how it can hear, how it can choose where to live based on the sound. So we brought some of these coral larvae into the lab at the University of Bristol, where we were able to fire miniature lasers onto the hair cells on the outside of the coral. And by playing different sounds to that coral larvae, we could see the hairs start moving in different ways using the lasers.

And so when the coral encounters a healthy soundscape, the hairs all start moving in this synchronised way which causes a spiralling downward swimming motion which brings that coral larva down onto the seabed.

We now realise that when we play the sounds of a degraded coral reef, which isn't such a great place for the coral to make their home, they just keep swimming in mid-water. They don't swim towards the sound. But as soon as we switch the track so that it sounds like a healthy coral reef, this behaviour completely changes. They move into a spiralling, downward, synchronised movement, almost like synchronised swimmers.

And that allows them to parachute down and settle into the habitat where they're going to have the best chance of surviving. As quickly as we're making these discoveries about the natural world, the really sad part of our work is realizing how quickly those natural cues can be lost. We've been working on the Great Barrier Reef for 20 years, and recently we've heard the reef die. A bleaching event in 2015 wiped out over half the corals.

When we visit the reefs after the bleaching event, it's just completely different. The colour has gone, the carnival of life has now gone away, the circus has moved on. It looks like a film set to a kind of desolate graveyard of dead coral, all overgrown with seaweeds, very odd occasional fish swimming around, looking out of place because of their bright colours. And it brings me to tears.

It's just empty. It's got this sense of death in the recording. There's almost no sound, an occasional rare snapping shrimp or a fish that may be vocalising, calling out, but no response. It's just this hollow, ghostly environment that you knew once was a carnival of life.

The deathly silence on a coral reef is not just tragic for us to listen to. It's tragic to realise that the reef is no longer calling in the next generation of animals that make it healthy. It's lost its pulling power. No more fish, no more crabs, no more clams. It's entered into a downward negative spiral to ever more degradation. But despite some of what we see, I still remain optimistic for the future.

Partly because I think that we have it in our gift to actually fix the environment, to fix the climate over the next century. But also because when we start to give nature a chance, we rebuild coral reefs or we give them greater protection. We hear this in our recordings. We hear the reefs recovering.

We hear the animals coming back. It's like the orchestra now has all its musicians coming back one by one, picking up their old instruments, starting to play again and the symphony of the reef, of a healthy biodiverse reef, then starts to come back over a period of two or three years.

So now we realise that we can hear reefs recovering when we give them a chance. We've found a way that we can actually hack into this and put recovery on steroids, taking it one step further by using recordings of healthy reefs and playing those back at restoration areas.

As soon as the animals start coming in, based on the sounds we're playing back, they make it their home. And they make that reef soundscape come back as a natural phenomenon of the reef, calling in the future generations. So it's only a short intervention that we need to do to then give that reef a chance of long-term survival.

Forever!

After 30 gigabytes, customers may experience slower speeds. Customers will pay $25 a month as long as they remain active on the Boost Unlimited plan. My dad works in B2B marketing. He came by my school for career day and said he was a big ROAS man. Then he told everyone how much he loved calculating his return on ad spend.

My friend's still laughing at me to this day. Not everyone gets B2B, but with LinkedIn, you'll be able to reach people who do. Get $100 credit on your next ad campaign. Go to LinkedIn.com slash results to claim your credit. That's LinkedIn.com slash results. Terms and conditions apply. LinkedIn, the place to be, to be. That was great. I loved that. It was really like a beautiful...

feeling, hearing that complexity of those sounds. Yep. How did you feel when you heard the dying reef? I mean, I don't think there's any other way. You feel lonely, right? It must be so alone to be like that one fish that's like trying to call on this dying reef.

And there's no one else to respond to it, right? Yeah. Really, like, just sitting and listening to that, like, it really carried a weight with it. But what was crazy is that it doesn't take that much to bring it back. To bring it back. It's this, like, really beautiful discovery because so often with these stories of people

habitat loss and conservation, you feel the negative feedback loop, right? But then when you feel it start to reverse, it's just so satisfying. Yeah, and this is a really good example of sustainable conservation. All we need to do is kickstart the process and then allow nature to basically change

take over. It's catfish, but catfish for good. Yeah, which is pretty different from what I'd say is the norm for trickery in the animal world because a lot of species have evolved to catfish each other, to like use lures to pull each other in. Parasites do this a lot, right? Where these are animals that have evolved to manipulate their host to do things that are good for the parasite but not great for the host. Especially parasites that like

have to live in different animals to complete their life cycle. They will make the first host that they live in change its behavior in a way that continues the cycle. So like there's this flatworm that infects snails

As they grow inside the snails, they do this really wild thing where they make the eye stalks of the snail, these like glowing, pulsing colors. Really hypnotic. You can't look away from it. And so if you're a bird and you're cruising around for a snail snack...

This one snail is going to stand out. It's got a little neon sign that says, eat me. And that's going to pull you in, of course. Go in, swoop in, get your snail snack. Surprise, you now have worms, which for the flatworm, great. For the catfished bird, you know, they might have some issues with that.

And it's that dangerous attraction that sometimes is really common in nature. When you feel that attraction, that pull to someone, maybe acting on it right away can be a tricky proposition. Dr. Dino Martins has a great example of this. He's an entomologist at the Mpala Research Center in Kenya.

Around the Institute at our campus, we have one of the most remarkable creatures, the camel spider. The camel spiders are these large, gangly arachnids. They're not actually spiders. They don't have eight legs. They actually have ten limbs. To me, they're one of the most remarkable and beautiful creatures that occur in the desert.

They can be slightly terrifying to look at. They run very, very fast and they jump about and they terrorize students and scientists by climbing over their beds and jumping off the ceilings onto their dinner plate sometimes. And they're about the size of a dinner plate. So it is quite a dramatic moment when you first see them.

The female camel spiders are the ones who go out and hunt almost anything they find. They will happily catch lizards as well as rodents and shrews. They sort of jump on their prey and macerate it with massive jaws of which they've got two sets to completely subdue their prey. Part of a camel spider's life is obviously it has to find a mate. So what happens is on a nice moonlit night,

Females will emerge from their burrows and she will emit both chemical as well as auditory cues. The chemical is a pheromone. We don't know a lot about it, but we do know that it is irresistible to the males. And so the females release these chemicals as they leave the burrow.

And in addition to that, the females are covered in these bristles that rub against the sand. This sound is irresistible to the males. He goes from walking in a straight line to starting this incredibly frenetic, passion-driven running around. And this pattern of moving in a spiral will eventually lead him closer to the females.

The male cannot just approach the female directly. She's extremely aggressive and she's likely to tear him to pieces or eat him for dinner or an after-dinner snack. So the male now digs a little bit and the female comes out and he jumps back and then takes a few tentative steps forward, touches the female and jumps back again.

because he has to really make sure for the next step that she's in the right mood. So what the male now does is when he sees the female is somewhat receptive to his overtures, is he will come up to her and he'll grab basically the end of her body, which scientists call the opisthosoma. It's the softest part of her body, so it's a very vulnerable part for the female.

The male actually has to chew open part of the female's opisthosoma. At this point, the female goes into a trance-like state, and then mating proceeds. She comes out of this trance-like state, and then she goes back into the burrow. At this point, the male takes off as fast as he can, because after this, she might actually be hungry and need a snack.

That is the courtship and mating of the camel spider, which is one of those rarely observed events, but something we've been able to see in the desert at the Turkana Basin Institute. And it is really, really remarkable. Wow. So...

have had many a campfire living in Zimbabwe and South Africa and Botswana and I used to count myself lucky that I never saw a camel spider laughing

approach our campfire. But now, listening to Dino, I'm kind of like, oh, actually, I do want to meet this spider. I mean, I don't know if anyone else in my camping group will want the same, but now I'm really intrigued. Yeah, they're really cool animals. I've actually wanted to meet one myself for a really long time. Just a few weeks ago,

I got that opportunity. I was in Arizona. I was walking back at the end of a long day to go back to the hotel where I was staying. And I saw something just on the wall there, zipping around. I take a closer look and oh my gosh, it was so cool to see one in real life. This was not as big, sadly, as the one that Dino mentioned. But they really are quite speedy.

And that speed and that weird way of moving, it's part of what makes them those really incredible predators that Dino was talking about. And it's really fascinating to see how an adaptation for a certain part of life can kind of become that challenge for another. Because the camel spiders are such good predators and they're so quick to respond to prey and pounce on them.

When they actually need to talk to each other and mate, the male has an even bigger challenge because the female is so good at catching food. He's got all these additional challenges of, okay, I've got to figure out what she's up to, what's her mood like, respond to her situation and really pay attention in order to have a shot. Whenever my dad disapproved of a boy that I liked in high school...

And I liked him for probably all the wrong reasons. But my dad forbidding me from being with that guy just made him even more attractive. So I feel for these these solid fugitive males because she is the one for them. But he will get hurt. Yeah.

She's still a formidable predator at the end of the day. And yeah, that's kind of what courtship is sometimes, right? There's that push and pull of attraction and danger. Sometimes it's intense. Sometimes it looks beautiful. And sometimes it's a little bit of both. For example, one of the most famous nature sounds in the world has evolved both those characteristics, the beauty and the intensity.

I'm talking about the dawn chorus. It's beautiful to our ears. It's like the sound of the start of the day, right? My alarm clock sound is actually a bird dawn chorus. But I've always been curious, what does that actually mean to the animals? Because for a lot of birds, that dawn chorus...

It's about screaming out to all your competitors how you survived the night and that you're the best and that you're the one with the best territory and that you're the one that all of the other birds should mate with. It's like this competition. They're all showing off. Exactly. So it's not the early bird catches the worm, but it's actually the early bird gets the girl. That beautiful bird song is actually an intense competition and rivalry match between the birds outside your window.

it's still true that to us it sounds beautiful and relaxing. So we're going to leave you to chill out and immerse yourself in a few minutes of the British Dawn Chorus. This was recorded by naturalist and sound recordist Gary Moore, who's actually a regular recordist for the BBC Natural History Unit here in Bristol.

I think to be in a deciduous forest the last two weeks of April, first two weeks of May is one of the world's great wildlife events. I mean, I've been fortunate to travel the world, but during that particular month, you can keep your Serengeti, you can keep your rainforest. For me, it's definitely the UK and the dawn chorus in the UK. I believe that somewhere deep in our psyche, the returning birds...

bring a sign of the good times are on the way. You've survived the winter, you've survived the hardship, the returning birds, the returning song. Somewhere unlocks some sort of ancient meaning that the good times are on the way.

The BBC Earth podcast was hosted by me, Rotunda Shackleton. And me, Sebastian Echeverry. Our interviewees were Pauline Fleischman, Steve Simpson, and Dino Martins. The Dawn Chorus soundscape was provided by Gary Moore. Special thanks for the feature on Coral Reefs goes to Tammy Silva, Emma Weschka, Tim Gordon, and Eric Parmentier. Our producers are Jeff Marsh and Rachel Byrne. The researchers are Dawood Qureshi and Seb Masters.

Podcast theme music was written by Axel Kakoutier, and mixing and additional sound design was done by Peregrine Andrews. The production manager is Catherine Stringer, the production coordinator is Gemma Wooten, and the project coordinator is Linda Barber. The associate producer is Kristen Kane, and the executive producer is Debra Dudgeon. The BBC Earth podcast is a BBC Studios production for BBC Earth.

My dad works in B2B marketing. He came by my school for career day and said he was a big ROAS man. Then he told everyone how much he loved calculating his return on ad spend. My friend's still laughing at me to this day. Not everyone gets B2B, but with LinkedIn, you'll be able to reach people who do. Get $100 credit on your next ad campaign. Go to linkedin.com slash results to claim your credit. That's linkedin.com slash results. Terms and conditions apply.

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