快猫短视频

The following is a transcript from 快猫短视频鈥檚 CultureLab podcast. Subscribe and listen for free .

Christie Taylor: Science journalist Ed Yong is the author of . It鈥檚 just out in paperback, after being published last year. And it鈥檚 the story of over a hundred different species from around the world, and how they see, smell, hear and even detect electricity or heat in ways we can鈥檛 even begin to match.聽

You meet beetles that fly hundreds of miles to the heat of distant forest fires. The fish that communicate with each other in pulses of electricity. And our best friends 鈥� dogs, who smell the world around them the way we scroll social media.聽

All of these sensory modes give rise to what scientist Jakob von Uexk眉ll called the Umwelt 鈥� a world built by what the animal senses, that only they, with their unique perspective, can inhabit. But it鈥檚 also a thing we human beings, with our unique brains, can try to understand 鈥� which was exactly Yong鈥檚 goal in writing the book.聽

Ed Yong: I really hoped that it would spark feelings of curiosity and empathy, that it would help people to see the other animals in the world in a new way, but also the world around them in a new way. And just judging by the feedback I鈥檝e had, it very much is doing that. You know, we鈥檝e had really nice messages from readers saying that they鈥檙e walking their dogs more slowly or they鈥檙e pausing before they brush away a cobweb in the corner of their room to think about the spider that built it, or they鈥檙e watching the birds at their bird feeder in a new way.

One really lovely message I got was from a dad whose son was born with several sensory and learning disabilities who said that he was thinking about how to be there for his kid in a new way after reading the book, because instead of trying to think about what he would experience, given those constraints, he was now really focused on learning how his son experiences the world. So, you know, I want to be careful before drawing a comparison between non-human animals and people with disabilities, but I think the point still stands that empathy and curiosity are muscles that we can flex, and learning how to take the perspectives of lives that are very different from yours I think is a really important transferable skill that I hope the book helps to engender in people.

Christie Taylor: So, let鈥檚 go back to the beginning because this is a book about animal senses. But when we talk about senses, you go way beyond what I think of as the traditional five senses. If you wanted to rattle off a list, how many do you think there actually are to consider?

Ed Yong: Well, I think it鈥檚 really hard to put a number on it, because firstly in humans, there are more than five, right. So, there are the internal senses we often don鈥檛 think about. There are things like proprioception, which is how you know where your arms and legs are even when you close your eyes. And then when you go to other animals there are these exotic senses that humans don鈥檛 have.

So, songbirds can sense the magnetic field of earth, many electric fish and sharks and platypuses can sense the electric fields that living things give off. Rattlesnakes can sense the infrared radiation given off by warm-blooded prey. These are all things that humans don鈥檛 have. But other animals also meld the traditional senses in weird and counterintuitive ways. So, the antennae of ants and the suckers of octopuses, likely melds taste and touch into a single sense. You know, that kind of blending of information in the way that people with synaesthesia have. I think that鈥檚 very common in the animal world.

And then there are some exotic senses that could be thought of as offshoots of the standard five or not, depending how you think about it. So, you know, I said rattlesnakes can sense infrared radiation, they are detecting heat, which is not something which we can really do. But the organs that do that are feeding into the parts of the brain that process visual information, and some scientists think of rattlesnakes as essentially seeing heat, that infrared might just be another colour to them as red, green and blue are for us. So, whether you want to think of that as another sense or a weird offshoot of vision, I think is very much up for debate.

Christie Taylor: Yes, that鈥檚 really interesting, because the way the pathway that the brain is using for processing the information may be the same as one we have, but they have a different use for that pathway almost or addition to the pathway, I guess.

Ed Yong: Right. And so here鈥檚 another good example. So, bats famously use sonar to get around. So, they echolocate, they produce these high-frequency calls, and listen out for the rebounding echoes and use those to navigate around the world, to find how far they are away from insects or obstacles. That鈥檚, kind of, an advanced form of hearing, right, you鈥檙e just listening out for sounds. But the fact that the bat is always making the sound changes things. It means that echolocation is always an active sense, it鈥檚 always exploratory. Without the call, there is no echo for the bat to hear. And in that way, it鈥檚 a little bit like touch I think. It鈥檚 very similar to the way we use our hands to reach out and explore and grasp and manipulate and feel the world. Bats are sort of doing that with sound, and dolphins are doing the same thing with sound too.

Christie Taylor: Yes, that makes a lot of sense. And I want to get onto the central concept of your book which is that we鈥檙e not just talking the mechanics and the 鈥済ee whiz鈥� of how an animal does things that we can鈥檛. We鈥檙e also talking about the world that is created for them as a result, this concept called the umwelt. Maybe it鈥檚 not something we think about as often, but it鈥檚 actually very important. Why did you sort of land on this as the organising principle, you know, what the world is like for animals as opposed to just, gee whiz, a bat does this very well?

Ed Yong: Because I think it鈥檚 deeper and richer. So, often when we think about animal senses, a lot of the writing in this space is about animals doing things better than we do. It鈥檚 this shark is smelling X times better than we can smell or this fox has much better hearing than we have, and we鈥檙e sort of valuing animals only when they surpass our own abilities. But I think that鈥檚 a slightly cheap way of thinking about their lives. And the umwelt concept provides an alternative.

So, this was popularised in the early 20th century. And the word itself, umwelt, means environment in German, but it was used in this special way to refer to an animal鈥檚 sensory environment. So, not the physical things around it that it can touch and interact with, but the information that it has access to. So, the sights and sounds and smells and textures that it can perceive but that another individual or another animal might not be able to. And that I think is a beautiful concept because it tells us that despite the fact that we have this very powerful illusion of perceiving all there is to perceive, that really is an illusion.

Our perception of the world is woefully incomplete. And that鈥檚 a limitation that we share with all other creatures. We are great in some ways, but weak in others. You could argue the same is true for any species around us.

Christie Taylor: There鈥檚 a point where you鈥檙e talking about vision where you鈥檙e talking about, for example, a vulture can see downward with incredible clarity while it鈥檚 moving very quickly, but it cannot see ahead of itself, for example, and this is why they so often entangle with wind turbines. And that鈥檚 not like a 鈥渋t鈥檚 dumb鈥� sort of thing, it鈥檚 just it鈥檚 got this blind spot that it鈥檚 never needed access to before there were wind turbines.

Ed Yong: Absolutely. At no point before people created these giant machines would a vulture ever have needed to look at something directly in front of its head while it was soaring up in the sky. And evolution tailors the sensors according to the owner鈥檚 needs. But vision is a great example here because humans have very good vision. I mean, I don鈥檛, I wear ridiculous contact lenses, but theoretically as a species, we have very sharp eyes, sharper than anything except vultures and other birds of prey.

But sharp vision comes at a cost. You can either have an eye that is very, very sharp that has high resolution, or you can have an eye that does really well in the dark and is very sensitive. And for just simple physical reasons, you cannot have both of those things at once. So, this is a great example I think of how there are always trade-offs in vision. Some animals can see colours in pitch blackness, other animals can spot a rabbit from a mile overhead, but you can鈥檛 have both of those things at the same time. And I think that鈥檚 a great example of what we were talking about, that the sensors always constrain us, even as they expand our possibilities.

Christie Taylor: Well, and staying on vision for a moment and colour actually, if we鈥檙e talking about umwelt that we cannot perceive. One of the ones that really, I don鈥檛 know, struck my imagination in a really wonderful way is something that I think we talk about in very simple terms a lot, bees can see ultraviolet, we cannot, but it鈥檚 not as we write something as simple as, oh, there鈥檚 a glowing outline of ultraviolet around this flower, it is a whole range of visual frequencies, much like any other shade of colour. How can we even approximate understanding what that鈥檚 like?

Ed Yong: Yeah, I think with great difficulty. If you can see ultraviolet then there are patterns in the natural world that become obvious that we normally don鈥檛 see. So, a lot of flowers that we think of as being single colour actually have very vivid patterns on them, they have bullseyes and landing strips and other things that draw the attention of pollinating insects which almost always can see ultraviolet. But you鈥檙e right that ultraviolet is a range of different colours and there are many different shades, just as we recognise different shades of blue or green. And they will combine with the colours we see to create even more combinations of colours that we can鈥檛 perceive or imagine or even name, you know, the ultraviolet version of purple which is a mix of red and blue.

This gets even more complicated when you think about birds because humans and bees both have three kinds of colour-sensing cells in our eyes. They are sensitive to different kinds of colours, so, bees can see ultraviolet, but there are still three at core. So, you can re-colour what the human world looks like to imagine what a bee might see. But you can鈥檛 do that for a bird because birds have four kinds of colour-sensing cells, which means that they sense an entire dimension of colours that we don鈥檛 have access to. You know, 100 times more hues than we could discriminate or give name to.

And that is actually almost impossible to imagine, I think. You can鈥檛 recolour the world to what it might look like to a hummingbird or a crow because four in three just doesn鈥檛 go. And, so, I think that means that there is always going to be something about a birds鈥� eye view of the world that is fundamentally unimaginable to us, and I find that kind of cool.

Christie Taylor: So, when people say, let鈥檚 get a bird鈥檚 eye view of this, that鈥檚 actually impossible.

Ed Yong: Right. And I think this is an example of how our language is a bit limited too. When we say a bird鈥檚 eye view, really all we鈥檙e talking about is a view from a high perch. Right. So, it鈥檚 the same thing that we see but from above. But birds often have eyes on the sides of their heads. So, they will see a panoramic wraparound view of the world that again is very difficult for us with our forward-facing eyes to imagine. They will see this extra dimension of colours, so the world will be bursting with colour information that we can鈥檛 perceive. Just in terms of vision and just in terms of birds, like, some of the animals that we鈥檙e most familiar with, the world around us looks utterly, utterly different.

Christie Taylor: What about a different sensory landscape, and I鈥檓 thinking now about sound, sticking with birds. I think about birds with very good hearing and I think about owls. But what is that landscape then of hearing very well like for a bird like an owl?

Ed Yong: So, owls have incredible hearing as you鈥檝e said, and they also have precise hearing. So, I can more or less tell whether a sound is coming from my left or my right because my brain can compare the timing at which sounds arrive at each of my ears. Owls can also do that in the vertical plane because their ears are offset. So, if you imagine a clock face, an owl鈥檚 are are like at 2 and 8 o鈥檆lock.

Christie Taylor: Like askew.

Ed Yong: Right, they鈥檙e skewed, yes, they鈥檙e asymmetric. And that means they can very, very finely pinpoint exactly where a sound is coming from. And you can see this in their behaviour, so a great grey owl can pounce on a lemming that鈥檚 running inside a snow-covered tunnel because it can hear exactly where the footsteps are coming from, even though it absolutely cannot see the animal in question. That I think is incredible because those are noises that we probably cannot hear, they鈥檙e too faint. But the thing I find most amazing about bird hearing is that even in the sounds that we can hear, we鈥檙e still missing a lot of what they鈥檙e getting. And bird song is a great example of this. I鈥檝e started birding recently and-,

Christie Taylor: Join the club.

Ed Yong: Right. It is delightful to learn the songs of the local birds. But every now and then you鈥檒l hear a species that it really sounds like there鈥檚 so much more going on there than what my ears can detect. And in many cases that鈥檚 because there is.

Birds have hearing that operates at a much faster timescale. So, they can hear these tiny, tiny very rapid changes in both pitch and volume that our ears simply aren鈥檛 fast enough to detect. And those changes are really, really meaningful to birds, sometimes more so than the syllables or the notes that we think of when we try to duplicate birdsong.

So, I think birds are hearing stuff in their own songs that we鈥檙e not hearing, they are encoding and detecting meaning in parts of their songs that they can鈥檛 pick up and they鈥檙e sometimes ignoring the parts of the songs that we think are meaningful to our ears.

Christie Taylor: Is that like the old jazz clich茅 where it鈥檚 about the space between the notes sometimes more than the notes themselves, like, is that at all comparable?

Ed Yong: I guess a little bit. But I, sort of, see it as the shape of a note. We might think of a note as a single entity. But it鈥檚 like if you look at the spectrogram of a note, the way its frequency changes over time, and you really zoom in, what to us might look like what you would expect a child to draw a mountain like, just a triangle, actually is more like a city skyline, you know, it鈥檚 going to be jagged and bumpy, and those tiny variations are things that a lot of songbirds are picking up on.

Christie Taylor: I want to go back to something that I erroneously dismissed as umwelt 101, but dogs and their noses. These are animals that we live alongside, and many of us may feel like we understand them. But you write in great detail about the sensory or the scent landscape that dogs live in that we may not actually as dog owners or dog appreciators fully understand as much as we want to. What is going on in the nose of a dog?

Ed Yong: Yes. So, the anatomy of the nose is really specialised and it鈥檚 really specialised to give dogs an almost continuous olfactory sense of their world. So, when I inhale, there鈥檚 a single stream of air that goes down into my lungs and passes smell receptors in my nose along the way, and then when I exhale, all of that good scented air is washed out and then the cycle begins again. With dogs it鈥檚 a little different.

They have structures in the noise that split their air stream in two and one small slice goes into the part of the nose that is dedicated for smell and doesn鈥檛 get washed out on the exhale. So, it鈥檚 always got this reservoir of smelly stuff inside its head for it to process. And then its nostrils also add to that effect. So, you look at a dog, you鈥檒l see the nostrils curve round to the side so there are these side slits, that means that when the dog is sniffing along the ground and exhaling, rather than pushing scents on the ground away, it鈥檚 actually creating these rotating vortices that sweep these molecules up into its nose. So, a dog is effectively inhaling even on the exhale. And that means that its sense of smell is continuous.

Mine is very flickering. If I tried to do what a dog does and follow a trail along the ground, and I鈥檝e tried this in an experiment, firstly I start hyperventilating, but also I lose it, that perception is very flickering, it鈥檚 like looking at a crowd through a strobe. But for a dog, I think it鈥檚 smooth and continuous.

And not only do dogs have this incredibly sensitive sense of smell which we鈥檙e used to, right, we know dogs can smell drugs and explosives and they can do all these cool party tricks that they鈥檝e been trained to do. I think smell also gives dogs a very different perception of the landscape around them in a way that vision doesn鈥檛 really because smells can linger, smells can give clues about the past. Vision is a very instantaneous sense, smell is not. Smell is also historical.

So, if a dog is sniffing a patch of pee on a sidewalk that another dog has left behind, it is basically smelling into the past, it鈥檚 learning who walked past this point before, it learns stuff about their identity, maybe their age, maybe their health, their diet. It鈥檚 getting tonnes of information here. And I walk my dog now and he sniffs, like, patches of pee that other dogs have left behind, I think of it like me looking at my Instagram feed or my Twitter feed, it鈥檚 social media, my dog is enjoying the process of working out what the other dogs in the neighbourhood are doing, where they鈥檝e been, what they鈥檝e been up to. Smells also travel far ahead of their owners, so when we come home, our dog is always at the door greeting us, and I think that鈥檚 partly because the smells that we release are preceding our arrival.

Christie Taylor: I want to talk about at least one sensor or umwelt that involves systems that we do not have as people. And I feel like I had the most holy crap moments when you were writing about electrical sensing, which you said that one in six vertebrate animals can do and it鈥檚 very likely we have an ancestor, you know, back in the fish family that can do this too, like we鈥檙e descended from electrosensing animals. How does that work?

Ed Yong: It works certainly very well in the water because all living things in the water produce very weak electric fields. And a lot of animals have the ability to sense those fields. So sharks can famously do it, catfish can do it, platypuses can do it, and a lot of electric fish can do it too. So, you know, the basic version of the skill is, can you detect the electric fields that other living things are naturally giving off. And this is a very good way of finding your prey because it is very hard to stop yourself from producing those fields, maybe impossible.

So, if you can detect them, it鈥檚 a very surefire way of finding things that might be hidden from other senses. But then some animals have taken this to another extreme where they, much like bats producing sounds that they listen for, there are electric fish that produce their own electric fields and that navigate by sensing how those fields are distorted by objects around them, whether it鈥檚 conducting objects like plants or insulating objects like rocks. The electric eel is the most famous example of this, but there are a lot of electric fish that don鈥檛 produce dangerous or a fatal amount of electricity, they are much weaker, but they still do this incredible thing where they鈥檙e using the electricity to sense the world around them.

Some of them can also communicate using electricity. So, they鈥檒l make these electric pulses that they use to sense their environment but that they also use to exchange messages with other electric fish. And there are parts of the world 鈥� in the Amazon, in many rivers in Africa 鈥� where you can drop an electrode into the water and suddenly discover that there is this incredible electric chorus of tons of electric fish chatting to each other in a way that no human could possibly hear unless you had the right tech.

The thing that really blows my mind about the electric fish is this, you know, I said that they use electric pulses to navigate and to communicate, and it鈥檚 the same pulses that are used for both of these purposes, which means that for all these fish, communication and perception are really starting to blur with each other. There will be cases where a fish that loses a fight with a rival acts submissively by turning off its electric field, you know, it鈥檚 like waving a white flag by going silent.

But of course doing that also robs it of its main perceptual ability, you know, it means that the fish can no longer sense a lot of things in its surroundings that it could previously sense. And I think that blurring of perception and communication is unusual for these animals, and also quite hard to imagine.

Christie Taylor: You also, I think this could have been less startling to me, but you don鈥檛 need water to detect electric signals either, and going back to things that bees know that we don鈥檛, they also seem to detect the electrical fields of flowers, which flowers have electrical fields at all is a new fact for me.

Ed Yong: Right. I think it鈥檚 very shocking to me too. But around the world, there are tens of thousands of lightning storms going on at any time. And all of this creates a planetary electric field, a change in voltage between the ground and the sky. And because plants are electrically grounded and because they grow into that field, they themselves distort it, they have an electric field around themselves whose shape depends on the shape of the flower, its intensity, it depends on different characteristics of the plant. And bees can detect this.

Bees have small hairs on their bodies that bend and deflect when they encounter electric fields. It鈥檚 like if you rubbed a balloon and then you put it over your arm, the little hairs will move. The same thing is happening with bees when they encounter flowers. And I think that鈥檚 incredible because this was only discovered a few years ago, just shortly before the pandemic happened. And I think it鈥檚 likely to be very common among insects. A lot of insects have these small sensory hairs, and it鈥檚 likely that they are also tuning in to the electric world of the plants around them in ways that we鈥檝e only really begun to imagine. You know, when a bee visits a flower, it鈥檚 going to change the electric field on that flower.

Christie Taylor: Oh, yeah.

Ed Yong: Right. So, by sensing the electric field of a flower, a bee might be able to tell if one particular bloom has recently been visited by another bee and might be lower on nectar, so that鈥檚 one possibility. Then you could ask, like, wait, could flowers lie to bees using electric fields? Like, can they switch off or have ways of regenerating that field very quickly to send messages about how much nectar they have? I think that these are the kinds of questions that this discovery raises.

And it hints that this entire sensory landscape that exists in the most familiar settings, you know, I鈥檓 looking at my back yard right now and there are tons of flowers and I can see bees polishing them right now, what are they sensing? Ultraviolet is part of that, but electric fields are part of that, and what else are we missing? What the bees do I think is that they re-past something really familiar to us in a new way, and that鈥檚 really what I wanted the book to do.

I look at the gardens and the parks that I love spending time in in a very different way now that I know the kinds of information that flowers and plants might carry. And it鈥檚 one of my favourite examples because I think it highlights another really important theme in the book, which is that the senses are not merely passive receptacles for information in the world, but they actively shape and construct that world.

So, think about the colours of flowers. Clearly those colours are meant to attract pollinating animals, mostly insects. And you can actually take all the colours of all the flowers in the world and ask what kinds of eyes would be best at telling apart these colours. And some researchers have done this. And what they鈥檝e come up with is that the ideal eye for seeing flowers is basically the eye of a bee. Three kinds of colour-sensing cells, most sensitive to blue, green, ultraviolet, that gives you the maximal ability to tell the difference between all the hues on the blooms around us.

And so you might think, oh, so bees have evolved eyes that are really good at sensing flower colours. And actually that鈥檚 completely the wrong way round because bees and their ancestors, their eyes came first, and then flowers evolved later. So, flowers have evolved colours that ideally tickle the eyes of bees. And that鈥檚 just beautiful to me. That means that simply by existing and observing the world, the bees have painted the flowers that they then visit. And it means that beauty is not just in the eye of the beholder, but it exists because of that eye. So, the senses very much influence the form that beauty takes in the natural world.

Christie Taylor: I don鈥檛 want to let us go without also talking about peril, because wherever there is wonder, there is often peril as well. And, you know, you鈥檙e right about the way that we are flooding so many animals鈥� umwelt in with light and sound and I am sure also electricity and vibration and all of the other things that they are trying to make sense of, you know, how bad is it, and how do you want us to think about the power we have over the sensory worlds of other creatures?

Ed Yong: Yes. It鈥檚 pretty bad. So, humans pump light into dark spaces and sound into quiet spaces. And we don鈥檛 think of light and sound as pollutants, they don鈥檛 have the same visceral disgusting reflex that plastic in the ocean or that chemicals billowing from the smoke stack might have. But they really are pollutants and they can harm the creatures around us. So, light at night can take hatchling sea turtles away from the ocean up a beach where they get hit by cars or where they die from starvation.

Light at night can distract pollinating insects away from the flowers they鈥檙e meant to visit. Sound in quiet spaces can put off animals that might otherwise thrive there, can drown out the alarm calls and mating songs that animals need to hear. By making the world a brighter, louder place, we have made it a less conducive world for many of the creatures around us. And I think this is another example of how our tendency to focus on our own umwelt and forget that other creatures live in a very different sensory world can harm them.

So, we talked about how this is true for dog owners who yank their dog away from smelly opportunities, light and sound pollution are a much more extreme and I would argue important version of that failure, the failure to think about what other animals are experiencing and to tailor our world accordingly. We can do better at this and I think that it does behove us to be better custodians of the world, not just in the obvious ways but in the subtler ways that are nonetheless very important and impactful.

And I think there are selfish reasons to do so too. I鈥檝e called sensory pollution the pollution of disconnection because it severs other animals from the information that they need to survive, but it also severs us from the natural world. It means that at night most people in Europe and North America don鈥檛 see the stars, can鈥檛 see the Milky Way. It means that none of us have really experienced genuine true quiet and just the profound beauty of that. It means that many of us can鈥檛 hear the animals that are right on our doorsteps.

There was a reason why in the early pandemic a lot of people suddenly started hearing birds for the first time. It鈥檚 not because birds were flocking to these areas that humans weren鈥檛 in anymore, it鈥檚 that the birds were always there, you just couldn鈥檛 hear them. And I think there鈥檚 a deeper loss there by severing ourselves from the nature that is all around us all the time. It makes nature feel more distant, more remote, less connected to our daily lives and therefore less worth knowing about and protecting. And I think that鈥檚 a huge cost at a time when nature absolutely requires our best and most concerted efforts to cherish and to protect.