Instant Genius - How bats became one of the planet’s most successful animals

Episode Date: September 18, 2025

It’s a little-known fact that bats are one of the most successful animals on Earth, with almost 1,500 different species currently identified. Their agility in flight and prowess as hunters, wide-ranging diversity in size and behaviour and ability to adapt to almost any environment have allowed them to conquer almost every corner of the globe. But despite their success, many species of bats are now under threat. In this episode, we’re joined by ecologist and neurobiologist Prof Yossi Yuval to talk about his latest book, The Genius Bat – Understanding our Most Mysterious Mammal. He gives us a breakdown of bats’ sophisticated ability to ‘see’ the world using sound, tells us how despite their reputation as terrifying blood-thirsty predators, vampire bats have highly developed social networks and will even share their meals with other members of their roosts, and also explains how the loss of bats could have a huge effect on the ecosystems in which they live. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Visit name audio.com to learn more. Hello and welcome to Instant Genius, a bite-size masterclass in podcast form. Every Monday and Friday you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. It's a little-known fact that bats are one of the most successful animals on Earth, with almost 1,500 different species currently identified. Their agility and flight and prowess as hunters, wide-ranging diversity and size and behaviour,

and ability to adapt to almost any environment, has allowed them to conquer almost every corner of the globe. But despite the success, many species of bat are now under threat. In this episode, we're joined by ecologist and neurobiologist Professor Yosi Yuval to talk about his latest book, The Genius Bat, Bat, Understanding Our Most Mysterious Mammal. He gives us a breakdown of bats' sophisticated ability to see the world using sound, tells us how, despite their reputation as terrifying bloodthirsty predators, vampire bats have highly developed social networks, and will even share their meals with other members of their roosts. He also explains how the loss of bats could have a huge effect on the ecosystem.

systems in which they live. So, welcome to the podcast. Thanks so much for joining us. Thanks for having me. So today we're talking about your latest book, The Genius Bat, Understanding Our Most Mysterious Mammal. So an intriguing title. So why the Genius Bat?

Why not just the Bat? It's actually a tougher question than you imagine probably because it's not my title. So I originally just named it the bat. Oh, right. Yeah. And then, you know, you know how it is with publishing, and so they looked for a different title. And I was okay with this.

I mean, I really think that there are many animals that can be considered geniuses. But I do think that in this book, we show, I show and others that I interview show how remarkable bats are. And thus, you know, I think the title genius, they do deserve the title geniuses. Yeah, so let's have a look at bats then. So they're such unique animals. So the planet's only flying mammal for a start. That's worthy of interest in and of itself. But there's a whole lot more going on with bats than just this. So let's have a look at bats. What is a bat? Because there are an incredible amount of different species. Okay, so bats are of course mammals. I mean, we all know this. They're not birds. They, as you said, they're the only mammals that have the capacity of true flight, not just the jumping or soaring, real flight. They have a few really remarkable characteristics. So, I mean, of course, they use sound. They use what we call sonar or echolocation to navigate. Dolphins do that too,

but still bats are the only ones that will do this above water or in air. They have a remarkable immune system. People talk a lot about their ability to cope with viruses these days, which might also have effects on human health. And of course, actually, I'm not sure how many people know, but they also have a remarkable longevity. So even though they're small animals, some of them very, very small, they can live very long. So some of them can live dozens of years. There's a small bat, a seven-gram bat. I mentioned it in a book that was found in nature, 41 years after it was caught for the first time. So it was caught, ringed, and then recaptured 41 years later, which is remarkable for it's such a tiny animal.

So they vary hugely in size and shape, you know. Can you talk us through that? Yeah. So first of all, I should say that the reason, you know, I also study bats. I don't just write about them. And that's the main reason I think that I fell in love with them and that I'm so fascinated by them. And that's their diversity or variability. So, I mean, really, they're almost, as you said, they're almost, 1,500 species of bats, which makes them the second largest group of mammals on Earth after rodents, but they're probably the most diverse. So in terms of, you know, what they eat, you have bats that eat insects, fruit, nectar, vertebrates, like frogs, fish, blood. There are even several species of blood-sucking or blood-defeeding bats. So extremely diverse sizes in terms of size.

Also, the smallest mammal on earth is considered to be a bat. Some people say it's a shrew, Let's not argue. It's a 1.5 gram mammal. So tiny, tiny, tiny creature, which can navigate, fly, use sonar, you know, socialize all of this. And on the other hand, we have a huge fruit bat in the Philippines whose wingspan can reach almost 1.8 meters. So it's really a giant, right, if you try to imagine it.

So, yeah, indeed, huge variability. A lot of different strategies, super interesting, in my opinion. Yeah, that 1.8, that's almost my, I'm 100%. 84 centimeters. So that's almost my height. That's amazing. Yeah. So let's talk about a few things that they do have in common. So one of the most fascinating things I find is their wings and their ability to fly. So anyone who has seen a bat fluttering around, it's a very, it's very different from birds. They have a completely different way of flying and they're so agile. And I understand the wings are sort of fingers. Exactly.

So the wings have evolved from fingers that have elongated. By the way, the first fossil bards that we find are more or less 55 million years old. One of the chapters in the book discusses the early fossils. We do think that they evolved several million years earlier, but there's no real whole fossil found so far. And indeed, if you look at the fossil of an early bat, it's very clear. You see the fingers elongated, just like in modern extent bats. And in between the fingers, we have a very special membrane,

which is basically an adaptation of skin. It's just like your skin or my skin. But it's super flexible. I can push it and almost put my finger through it. And today we know that this membrane also has muscles. It, of course, has sensory organs. It can sense the wind. So really a lot of adaptations that we're only just now starting to realize.

Yeah, as you said, well, there's a lot of diversity. here too. Some bats are adapted to fly very far and very straight. There are some bats that migrate over thousands of kilometers. Others are extremely agile and can turn really on spot when they're chasing insects at night, for example. In general, you know, flight has evolved probably together with this unique sensory ability, echolocation, the ability to use sound to sense the world. So if you imagine a bat that is tracking, that is following an insect that is flying very erratically, this moth moving to the right, moving to the left. The bat first needs to use sound in order to identify where this moth is, to localize it,

and then it has to use its wings in order to pursue it. This is an extremely difficult task that, you know, if we think of modern robots, human-made, machines, missiles, nothing can basically perform so accurately. So let's have a look at echolocation, so that's another famous ability of bats. So first off, what exactly is it? Yeah, so I mean, if I really try to explain no, echo location 101, the bats emit sound. So they're shouting, just like we're talking right now, but usually they use very, very loud sounds, very, very intense. And also usually in frequencies that you and I cannot hear, so what we call ultrasonic frequency.

So basically, frequencies that are higher than the human ability to hear, but it's sound, just like you and I are now producing. Sound waves travel through air, just like, you know, if you think of a flashlight, so this will be, or just like, you know, my sound is now traveling towards you. And echoes return from everything. Also, now when I'm talking, I receive echoes from the walls and from, you know, the computer screen and so on. But my brain is an expert in filtering echoes. So my brain doesn't want these echoes.

It removes them in order for them not to confuse me. So, you know, if I'm processing sound, I don't want to have all of these echoes because they might confuse me. But the bat's brain evolved to do exactly the opposite. So it evolved to extract, to detect these echoes. Sometimes they're very, very weak. If you think of an echo returning from an insect, it's a very, very weak echo. And the bat's brain has evolved to analyze these echoes.

They have very special neurons and brain regions that are expertise on this. And they can say, first of all, they can say what it is. Is it an insect? Is it a plant? Is it another bat? Is it a wall? Where it is, very accurately. That's also extremely important, maybe how fast it's moving, and so on.

So really, they do all of this using sound only. In a recent study, we've actually shown, we placed these GPS devices on bats, and we show that they can navigate over many kilometers when using sound only. Okay, so basically what we've done there is we eliminated their ability to use vision by temporarily covering their eyes with a piece of cloth that they can later on remove. So it's very temporary. We're not hurting the bats in any way. And we show that they can still find their way

over many, many kilometers while only using echolocation. So it's quite an amazing ability. So if you look at it about, they've got these, like, huge big ears. But how about their vocalizations? Is there anything special about that? Right.

So this is a question, you know, people often ask this, and they're often surprised by the answer. The answer is that basically their apparatus is a normal mammalian apparatus. So they use the vocal cords just like you and I are using to emit sound, and they use their ears, just like yours and mine, to receive sound. They do have slight adaptation.

So the vocal cords are a little bit finer and more tense, and this allows them to emit ultrasonic signals. But, you know, it's really, if you look at it and you're not an expert, you would really say this just looks like any other mammal. And also on the side of the ear, it looks very similar. They just have an adaptation of what we call the inner ear, which allows them to also receive ultrasound, right? You and I need special devices to do that.

They have this ability with their inner ear. But generally, you know, it's very similar to your ear and my ear. Their brain has, of course, evolved dramatically in order to allow processing of these sounds, which is something that is... That's where their special ability, I think, lies. So having said that, we've mentioned there are, you know, over a thousand species of bats.

do they all echo locate? Yeah, today we know of more than 1,400 species, and the numbers are increasing because we don't know much about bats. There are many species that are what we call cryptic, and until we check their DNA, first of all, some of them might have never been found, and some others we think it's a species that we know, but, you know, once we look at the DNA,

we realize it's a different species. Of these 1,400 species, we know of something like 150, 200 species or what we call fruit bats, or more accurately, old-world fruit bats. You don't have them in the UK. You do have them in Turkey. I mean, that's the northern part

where you can find some fruit bats, southern Turkey. As their name suggests, they eat fruit, and usually they're bigger. And when you eat fruit, that's at least the hypothesis. You don't need echolocation because the fruit is easier to find

with using vision, maybe also olfaction. And one of the hypotheses, although we don't know for sure, is that the common ancestor of fruit bats and insectivorous bats could use echolocation. And then fruit bats lost this ability and switched to use vision.

They have very good nocturnal vision. And actually, I think they're very interesting species. And one of the bats I work on most is a fruit bat. Yeah, so we have the saying, like, oh, you're as blind as a bat. So how good is bats vision? Yeah, that's another myth that we should eliminate during this talk. So, yeah, all bats can see. Some of them see very well, as I hint.

many fruit bats can see extremely well. Usually, you know, it's very hard to compare, but usually, of course, their nocturnal vision is very good. Their resolution, their spatial resolution, and color resolution is not as good as ours. You know, we are highly, highly visual creatures, but still, they can use vision. I think that many, many bats, maybe even all bats, use vision for long-range navigation. So if they have to rely on cues that are very, very far, they will usually rely on vision, because echolocation, I didn't say this, but it extremely limited in range. You can only use it for very, very short ranges of up to maybe a few meters. We have shown in a in the lab in an experiment that bats can actually translate

visual information into acoustic information or vice versa actually. So what we've done is we train bats. One of the things that we can do in the lab is to train bats just like you train a dog. We've trained them to identify, to distinguish between two objects and we've trained them to do this using sound only, so in complete darkness, so only based on the echoes without any visual information. And then we played very loud noise in the room, so they cannot use the echoes anymore, and we turn on the lights. So now they can only see the objects. They cannot hear them anymore, and we show that they could immediately identify them. So this suggests that at least to some extent the bad brain can translate what it hears, what it receives,

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And I think most people would be interested if they're like Gothic fantasy, we're interested in the vampire bat. So this is so strange. So you have, I can't think of many animals on earth that drink blood, you know, leeches, a few insects. Now we have a flying mammal. What do we know about that? Yeah, I agree that it's one of the most fascinating groups of bats.

There are three species of blood-eating bats, all in Central America. You know, I must say when we say blood-eating, it means that they can eat a few milliliter. So it's less than a routine blood test that you do in the clinic. So it's nothing that, you know, you shouldn't imagine something too gothic. But yeah, one of the most interesting thing about these bats is there's social life, about vampire bats. So one of the things, and this actually, I interview, in the book, I interview all of the researchers or the main researchers who've been studying this behavior. So this is one of the classical examples in nature for what we call altruism or reciprocal altruism.

And the idea here is that these bats will sometimes fly out and not find food. So they don't find today's bats, for example, will commonly eat blood from a cow, for example. Occasionally, they don't manage to find blood to eat, and then they will come home to the roost. And what a few of my colleagues have found over the years is that other bats will regurgitate blood and actually feed these bats. So they will help them. And this is extremely important because the physiology of these bats is very fast. And if they don't eat within 44 hours, they might even die. So they're really saving them. They're giving them a few more hours of survival, allowing them to go out again and find the food. And the even more remarkable thing about this finding is that

it's not necessarily relatives that are helping them. So, right, the classical evolutionary theory suggests that, okay, I will help my relatives because they have similar genes to mine. But in this case, what Jerry Carter and Jerry Wilkinson, who are both interviewed in the book, have found, is that actually what these bats do is they generate long-term ties with other baths who are not necessarily relatives, and that's why it's called reciprocal algorithm. So, you know, I can help you today, and maybe you will help me in, you know, two weeks, two months or maybe even a year from now. So these are very, very long-term ties, which in many ways reflect or are similar to human

relationships. So it's really one of the most fascinating social stories about bats. It's funny in German that bat is called the Flying Mouse, but we also call the big ones, flying fox, the fruit bats. And of course, fruit bats, the clues in the name. So, you know, how did that happen? It's such a difference. Blood versus fruit.

Yeah. So I already mentioned that the variability in feeding habits is enormous in bats. You could find bats eating anything, basically, including birds, by the way. There's some bats that will catch flying birds at night. But, yeah, I think fruit bats are among the most interesting ones in terms of their cognition. So we don't know exactly early fruit bats appeared somewhere in the fossil record. I think 35 million years ago, we don't know exactly how this happened, but I think that eating fruit requires a cognitive capacity that is very, very interesting. So when you eat fruit, its location is

known. So you have to remember many, many locations in the forest where there are fruit trees, right? But what is not known or what you have to track is time, because these trees only provide fruit during certain times of the year. And you might also need to track competition. because maybe there was a lot of fruit yesterday, but maybe it was all depleted. Maybe somebody ate it. So this now requires you to map in your brain, to map space where things are,

and also maybe time, right? When have you visited this tree? How long will it still provide fruit? And if you think of this, this is very similar to things that we humans can do, right? We know where things are in space. We also remember when we did things, we sometimes call this capacity episodic memory.

So that's one of the reasons why we in the lab study fruit bats because we hypothesize and others have also suggested that this reliance on this type of food requires to develop these cognitive capacities. And indeed, we have shown in several GPS studies that bats know exactly where food is and that they also track time. So they probably remember when was the last time they visited a fruit tree and they will adapt their behavior accordingly. So they will not return to a fruit tree where they know that it's the chances of finding

fruit are very low. This is very, very high cognitive capacities that are very similar to what we humans do. Do you think that feeds into why the fruit-eating bats are so big? Yeah. So, I mean, you do have small fruit-eating bats, but in general, you're right that on average they tend to be bigger. There are several reasons for that. And we, you know, with evolution, we never really know. But, I mean, one of the things is you don't have to be as agile as when eating very small mosquitoes. Right? Another thing is, you know, there's a lot of big fruit. And if you eat a big fruit, you basically need a big jaw and very strong muscles. I guess that's why you have a tendency of fruit bats to, you know, the general pattern is that they will be larger than the average insectivorous bats with which sometimes have to forage on these very, very tiny insects and have to be extremely agile.

But yeah, I guess that's more or less the reason. By the way, we don't see, so bats are always smaller than birds. We don't see bats that are as large as vultures or albatrosses. So this huge bad that I mentioned has a very large wingspan, but it doesn't weigh more than, I think, 1.5 kilograms. So it's not like an 8 kilogram pelican or something like that. They are smaller than birds. So we've talked about a lot of fun stuff now,

but the sad truth is a lot of bat species are in trouble now. So, you know, what is the situation there? Yeah, so there's several causes, of bat mortality worldwide. Of course, all of them are somehow related to humans. I will maybe mention just a few. There's a fungus. It's called the White Nose Syndrome,

mostly active in North America, which has resulted in the death of millions and millions of bats all over North America with some colonies completely disappearing. It's been devastating. In many ways, it reminds me of the COVID pandemic, But with bats, we don't have also thousands of scientists working on this, and thus we don't really have yet a solution. There are some positive findings suggesting that maybe some of the colonies are now becoming bigger again. And so that's one huge cause of mortality.

Another one is wind turbines. So green energy actually is also resulting in killing a lot of avian animals, including birds, but also a lot of bats. and this is also something that we're just now starting to understand and also to regulate. So a lot of my colleagues, and I interview a few of these people's in the book. A lot of my colleagues are very active in setting regulations. For example, one of the things that you can do is stop the activity of the turbines when the wind speed is low. That's when bats are active. Anyway, there's not a lot of energy being produced during these times, and that saves most of the bats.

And all you need to do is to convince the energy entrepreneurs to do this, which is not always, easy. But in general, I would say, you know, it's the human interaction or interference with nature that is causing bat mortality. As usual, you know, it's our invading natural, more and more natural habitats, whether it's for building roads or building cities or, you know, just exploiting natural resources. So in one study, for example, we show that sick bats will avoid any contact. So bats that are sick will actually, you know, humans are really concerned. about bad disease, but we show that a sick bat will actually stay in its roost and avoid as much as it can any contact with anyone. So the main way to get infected by such a bat as a human is to go

into the roots, right, and to interfere and to get closer to the bats and to force the bats out and to force them to interact with us, which is what we generally tend to do. So I mean, this is just part, you know, bats are no different from the general biodiversity crisis. And that is, of course, just a result of how we handle our natural resources, which, you know, it's something we just have to do better. Yeah, so off the back of that, a lot of people may say, well, bats, you know, what good do they do for us? But surely they play a vital role in the ecosystem. Right. So, I mean, first of all, actually, the word ecosystem already, you know, that's the answer, right?

It's an ecosystem. We don't understand it. We will never be able to understand it. If we affect one part of it, we clearly affect other parts in ways that we cannot predict and don't know. So I can give you an example for one very clear and obvious relationship. So many, many bats prey on insects and reduce the abundance of insects. And a very strong correlation has been shown in the U.S. between states in which there's a lot of bat mortality due to that fungus that I mentioned earlier and between the use of pesticides.

So basically when there are less bats fewer bats, then farmers are using more pesticides. And recently, just last year, a paper came out that showed a correlation between the use of pesticides and toddler mortality, baby mortality in the U.S. So of course we don't know for sure that there's a direct link, but the correlation is very, very strong. And you can imagine how, you know, fewer bats due to our activity causes or results in use of more chemicals, eventually consumed by us and affecting our health. So one sort of final question.

Are you optimistic about the future of bats? Wow. I think, I mean, this is a general question. I don't think bats' future is any different from a nature's future in general. You know, on the one hand, I think everything is extremely complicated. I think we can. So these are very, very complex systems. with a lot of connections and we're not good in predicting what's going to happen.

So, I mean, even when we're sure we say, you know, global warming is going to do this and that, it's very hard to predict exactly what will happen due to our effects on the globe. You know, in general, I am optimistic that at some point that is going, it has to be very close. And I think you do see some evidence that this is happening. We will realize that, you know, we are changing the planet drastically and negatively. and this will lead to better regulations that will, in general, eventually must assist everyone, including bats. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. That was Professor Yossi Yuval.

To discover more about the topics we've just discussed, check out his book, The Genius Bat, understanding our most mysterious mammal. If you liked what you just heard, then please do consider subscribing to Instant Genius on your preferred podcast platform. If you'd like to see our guests and hosts in person, then please do also check out our YouTube channel at Science Focus. The current issue of BBC Science Focus magazine is out now. Pick up a copy wherever you buy your favourite magazines or download us on your app store of choice. You can also find us on Apple News or online at sciencefocus.com. This podcast is sponsored by name, audio and focal.

The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analogue warmth. Alongside French acoustic specialist vocal, Name creates high-end audio systems combining innovation with craftsmanship, so you can listen to music, just as the artist intended. Discover more at nameaudio.com.