The physics and biology of flying mythical beasts (feat. the yogscast)

Thanks to for sponsoring this video Fantasy is filled with incredible flying creatures from the dragons of Game of Thrones
to the hippogriffs of Harry Potter. They’re unlike anything we see in the natural world in both form and size. Thank God. But being both a serious geek and a scientist, I can’t help but wonder:
Could these creatures really exist? Does the physics add up that they could fly? To answer this question in this video I’m going to apply real physics and biology to fantasy creatures by looking at extant and extinct species of bats and birds and by talking to experts on how those creatures fly. But to begin with, we need to know a bit more about flying fantasy creatures, and while I know a few things about fantasy, I happen to know some people who are much more qualified to talk about it. My name is Mark Hulmes I call myself a professional dungeon master, which sounds very very – full of myself. I run a Dungeons & Dragons campaign called High Rollers. We have our own Twitch channel, but we’re also partnered with the Yogscast that we stream on every Sunday at 5 p.m. GMT and we’ve been doing it for two years now. My name is Mark Turpin or Turps from the Yogscast. I’m the CEO here. The way I met the guys and got my job and all of that is I’ve been playing World of Warcraft now for about 15 years. It’s where in essence the Yogscast was formed and it’s where I spend the vast majority of my time. And I’ve been playing and talking about World of Warcraft for – probably in time most of my life. So it’s fair to say then that these guys know their stuff. I asked them to go through what kind of flying creatures exist in fantasy and got a comprehensive list. Yeah, there’s a lot of them. Griffins, dragons, the Horde had wyverns, manticores, chimeras, bone drakes, pegasus, hippogriffs, beholders, horses can fly in Warcraft. Sometimes they give them wings and
they’re like Pegasus, sometimes they just have sparkly hooves. There’s a creature called a darkmantle,
which is like an umbrella that’s like evil and is like an octopus umbrella that like falls down from the ceiling. It’s very very weird. Some of the old D&D stuff is very very strange. There’s a piloted sky golem,
which is basically like an Iron Man suit. You just kind of put it on and – whoosh! – off you go. So you have creatures that fly via magic
like the beholder who’s a big bag of floating eyes, winged creatures or bat winged creatures. And I think like winged creatures you’re talking about things like griffins, pegasi and then the bat wings is for creatures like chimeras, manticores, dragons, devils, that kind of stuff. And I think they fall into those two categories. So necessarily disregarding those creatures which fly exclusively through magic, we’re left with mythical creatures which fly in a way comparable to real animals. To begin with, let’s focus on those creatures with bird wings. But, it turns out there’s something of a problem with applying physics to bird flight. We don’t really know how it works. So we’ve got a good idea of how birds and insects and planes fly, how they generate lift, but it’s a very complex interaction of forces. And yeah, we still don’t have it all quite nailed down. That’s Dr Alex Evans who just completed his PhD in bird flight. My PhD is on the biomechanics and energetics of bird flight. I work with birds, mostly small parrots. We have a wind tunnel at the university, so we’re able to fly them at a variety of speeds and whilst they’re flying we can measure various mechanical and metabolic aspects of their flight and we can also film the birds flying and generate kinematic analysis and 3D model reconstructions of what the wings are doing in flight. So birds don’t all just fly in one uniform way. There’s a variety of different styles of flights depending on how big the bird is. Bigger birds tend to have a slower wing beat and they generally make use of energy efficient methods of flying such as soaring and they’re able to fly- sustain flight for a very long time with little energy. Whereas other birds, much smaller birds,
tend to use flapping flight a lot more. But even they don’t just flap all the time. They might have a bounding flight where
they’re flapping for a certain amount of time and then they’re gliding for a certain amount of time. So it varies a lot depending on how fast the bird’s going, how big they are, generally what they’re using their flight for,
whether it’s hunting or escaping? So to apply physics to our flying mythical creatures, we have to be more specific
in how we expect them to fly. Looking at the creatures in World of Warcraft and D&D, most of the wings seem to be similar to those of medium to large raptors like eagles and hawks,
which fly using a soaring or intermittent flapping gate depending on what they’re doing. Given this information, we can now ask a bunch of questions. Perhaps the most basic of which is: Based on the species we know fly in this way, are the wings depicted on fantasy creatures actually large enough to carry them aloft? To try and answer that question I use this paper published in 1989 by Mendelssohn et al., which measured various characteristics of a large number of African raptors. Using data from this paper, if you plot the mass of these species against their respective wing spans, you get this graph. As the mass of the bird increases, so too does its wingspan, as we’d expect. If you could fit a line to this data, you could extrapolate and ask for a very heavy mythical creature like a griffin, how big would its wings need to be? However, this data isn’t linear.
You can’t fit a simple straight line to it. So my idea of a simple extrapolation to much heavier animals didn’t work. Fortunately, Dr Evans had a much better suggestion. Because an alternative way of measuring wings to wingspan is wing area. And wrapped up in the wing area is information about how a bird flies in just two numbers. Firstly, if you divide the wing area of a bird
by its body mass you get a quantity known as wing loading. This is effectively the amount of weight that each square centimeter of the wing has to support in flight. That’s the first number. The second number is the aspect ratio of the wing, that is how long the wing is versus how wide it is. So an albatross has very long wings with a relatively low area and so has a high aspect ratio, while a puffin on the other hand has adorable short wings, but they’re wide so has a low aspect ratio. If you scatter plot these two quantities, the wing loading and the aspect ratio for a variety of bird species, then you get a really interesting graph. Birds which soar and don’t really flap their wings like swifts and albatrosses are up here at the top. Compare that to birds which can only just about fly
like puffins, which are way over here on the right. Populating this graph with lots of species you’ll see that the African birds of prey in the paper are all clustered around one area. That means two things. Firstly, that their wings all share roughly the same wing loading. If you plot the wing area of these species against their mass, it’s a lovely straight line. That means that we can extrapolate it neatly to a giant mythical animal and get a rough prediction of how much wing area
it would need to fly like an eagle. Secondly, the birds all share approximately the same wing aspect ratio. And because of this we can convert the predicted wing area to a predicted wingspan. So our wing area graph allows us to predict a wing area for any mass of animal that we want and we can then convert that wing area to a wing span by assuming an aspect ratio informed by the data in the paper. What we find is that for an animal flying like a raptor and weighing a ton – the weight of a large horse and so what I approximated the way every creature like a griffin would be – its wingspan would need to be just under 20 meters. For context, that’s nearly double the wingspan of the classic Cessna 172 light aircraft. For a giant creature like a griffin to fly, it would need to have huge wings. Much bigger than it’s depicted to have in for example World of Warcraft. What’s cool about this calculation though is that you can calculate a wingspan for a flying creature flying like a raptor with any mass, including the mass of a human – I weigh about 90 kilograms.
– 90 kilos. So you would have a wingspan just shy of
6 meters if you were a bird. – So about three meters either way?
– Yeah. Which incidentally is the wingspan of one of the very largest birds in the fossil record, the condor-like Argentavis. Which must have been absolutely terrifying. However, there is a huge problem with this analysis. It’s not just because in adding wings to a body,
you’re increasing the mass of the body, and so increasing the size of the wings needed, and so increasing the mass of the body and so on. It’s to do with how the wings would be powered and connected. The problem with most mythical creatures,
such as dragons and other large flying beasts that also tend to have four limbs as well as wings, is the musculature just doesn’t quite make sense. So for birds to fly, they rely a lot on the pectoralis muscles. So in the birds I work with, small parrots, they make up 75% of their total muscle mass and about 15% of their total body mass. And so if you have say a hippogriff, it’s got four legs and it’s pecs muscles are being used, they’re already attached to some limbs. So where these muscles that power the giant wings on their back come from,
I don’t know. How they would attach is beyond me. So for a creature depicted to have both
wings and front legs, like hippogriffs or griffins, musculature just doesn’t make any sense. With front legs there are no muscles left
to power the wings. So the feather creatures we’ve seen have wings which are too small and have no muscles to power them. So unfortunately based on known biology
they couldn’t exist. Dragons and dragonlike creatures however are a very different story. Hulmes was pessimistic about whether
anything like them could really exist. That stuff like dragons, like I mean you look at this and like the bulk of it, I don’t think that unless… I don’t know maybe the strength, its
strength would be enough to make it fly? I don’t know. I struggle with that one, but I would say
generally no, I don’t think so. But just wait, let’s apply some science. The closest parallel to dragon wings in biology are those of megabats. You might think of bats as being small insectivorous animals, probably not much bigger than your hand, but they get really big. These are Livingstone’s fruit bats, some of the largest bats in the world, kept in captivity at Durrell, a conservation charity on the island of Jersey Livingstone’s are about 1.4 meter wingspan
with about 700 to 800 grams body mass, so that puts them up there pretty high. The largest is – God, my Latin pronunciation is terrible – but it’s the golden-crowned flying fox from the Philippines and it can get up to I think it’s about 1.8 meter wingspan and and then they say a 1.6 kilo bat. So that’s a pretty hefty bat. That’s Ed Bell, a keeper of mammals at Durrell,
who works with the bats. I asked him how bat flight was different to bird flight. It comes down to the anatomy of bats. Effectively they’re flying with their hands. Chiroptera does come from the – I think the really bad breakdown is Greek for hand wing. So you’ve got basically the bones of our hand but imagine what makes up our palm
were mushed up under the thumb, so that big hook they’ve got is a lovely big thumb. The second and third digit, so your index and your middle finger, they create what would be like the leading edge of a wing, so if you’re thinking of like the Batman symbol, that will be the bit that goes all the way out right to the edge. And the two points that kind of come down and create those lovely kind of big arcs, that will be their fourth and fifth digits. And each of those has got a nice big really clever piece of skin attached between it. Really cool that she’s covered in like micro hairs ’cause they’re mammals just like us. They have got loads of hairs all over their bodies. Some studies are trying to show they can detect ever so slightly changes in like barometric pressure, airspeed, wind speed as they’re flying and that creates really like micro alterations in the surface of the wing. So when you look at a bat’s wing, you’ve got a perfect complete surface area, there is no gaps in it Now that differs from birds in the sense
that feathers obviously, they’re growing out of the bones
at the ends of the bird’s wing. And they’re controllable in a sense, they can shift and change a little bit, but they’re not as dexterous as a bat’s wing. So whereas birds can actually get
quite a lot of nice lightweight lift, they can be – well certain species can be incredibly agile, bats have got a little bit of an edge in terms of agility, because their fingers can control every single part of the wing membrane. They can collapse, they can crunch
and they can allow that kind of instant turn and movement. What I wanted to do for the bats was the same calculation we did earlier for birds, extrapolating from current species
to some huge mythical animal. But Ed mentioned something really interesting about bat flight specifically that makes such extrapolation impossible. There’s a limit to how much muscle and kind of like weight to muscle ratio and also flapping motions that a bat can create when she lifts its way off the ground. Exponentially, they wouldn’t be able to kind of have more muscle and flap harder, so there is like a cap on how much a bat could weigh and they estimate about 1.6. At the minute will probably be the heaviest and as far as the fossil record goes as well that’s probably the biggest we’ve ever seen. I’ve got a paper I can send you to have a quick flick through. That was this paper from Norberg and Norberg, which is a fascinating if dense read. Basically the authors looked on
how as bats get larger and larger, the wingbeat frequency required
to take flight decreases. So bigger bats don’t have to flap their wings as quickly as small bats to take off. But at the same time, the fastest that a bat can beat its wings also decreases as the bat gets bigger. Their wings just get too big to flap quickly. And interestingly, the maximum wingbeat frequency possible decreases faster with size than the minimum wingbeat frequency
required for flight. So that means there’s a theoretical limit on how big a creature can be with bat wings and still be able to fly. A limit that we’ve probably already hit in the Philippine golden-crowned flying fox. Oh my god, I forgot how big it was. This kind of kills the discussion of dragons dead. Do you think it’s too soon to make that joke? But if we assume that mythical creatures have some different muscle composition or wings with slightly different properties, then maybe we could paper over this So I asked Ed which mythical creatures he thought could exist based on some modified bat biology. Wyverns could work. They’ve got like the same kind of body structure in a way, maybe a quite large tail. I think mass size – that when they start to get as big as dragons are depicted, I just don’t know how that could ever lift off. Smaller dragons maybe. If you had like baby dragons or all the dragons from Game of Thrones before they got too big, I could see them working. But when they get to like full size
and you can start riding them, I think physics might be on the other side and that’s where magic comes into it so completely fine Relying heavily on this excuse of magic then, Hulmes and I decided to do a bit of backyard maths on the ancient red dragon model he had. It doesn’t have bird wings, but we thought it might be fun to see
what gate it might have. Measuring its wings to the best of our abilities and trawling various D&D resources for its weight, we estimated the dragon’s wing loading and aspect ratio. And comparing them to the bird species from before, it places on the graph here. Very similar to condors. So not flying like a megabat at all. Instead it would soar and probably need help in taking off, like jumping off a cliff So apparently it would be about the same as a condor. There you go, look at that! If it like – if we ignore all the other physical problems. The way I’ve always done it is like for them to take off is like a lot of work, like they have to really kind of get going but then once they’re up
they can kind of just open their wings. Based on his knowledge, Ed actually agreed with this kind of
flight pattern for dragons and wyverns I guess if a dragon lived on top of a mountain and was prepared to throw itself off and get enough lift to be able to take off and fly, yeah, it could happen. That would be one to see. Unfortunately the way things are going, the Livingstone’s fruit bat might soon be just as mythical as the dragons and griffins we’ve been talking about in this video. It’s critically endangered. Ed works on stopping the species from going extinct. Yeah, it’s a priority project for us on the mammal department. At the minute their numbers are about 1260 across about 20 to 30 roosts on the two islands. So they’re incredibly low, and the biggest threat at this minute in time would be a one-off cyclone that could just pretty much decimate the entire population. So having them here in captivity is still a critical safety net for the population, but it also facilitates a massive amount of research. We’ve got really good partners out in the Comoros called Dahari. They’re an organization we helped establish back in 2013, but they’re a complete separate NGO. They are doing amazing community agroforestry and agricultural work. Durrell and their partners in the field do truly fantastic work saving species from extinction
and working with local populations. I’ll leave a link in the description so you can learn more about their work with loads of different animals and if you have any money going spare, every single penny donated makes a real difference to species like the Livingstone’s. So after all this analysis, which mythical beasts could really fly? The major problem with a lot of the species
shown in fantasy is the musculature. Pectoral muscles are needed to power wings. So any species shown to have both front legs and wings? Doesn’t really make any sense. From a typical flying pantheon that pretty much just leaves wyverns. Although two other possible species which Turps and Mark didn’t mention are cockatrices and harpies. While real-life biology indicates that harpies,
women with wings for arms, could exist, they would need a much bigger wingspan than is normally depicted. Dragon wing creatures like cockatrices and wyverns wouldn’t be able to flap their wings fast enough to take flight. But if we allow for a little bit of magic or even just alternative biology these creatures might fly in a similar way to condors, more about soaring than flapping and with an assisted takeoff. But if you play Horde, your mount might just be possible in the real world. At the end of the day though does it matter that the creatures in World of Warcraft and Dungeons & Dragons are unphysical? No, absolutely not. I’m not looking for the real world in D&D. Sometimes the brilliance of fantasy is that it’s not real and that it’s completely different and it’s imaginative and you can go somewhere. The beauty of Dungeons & Dragons, and I tend to favor campaigns that we call high magic settings, you can’t get that stuff in the real world. Like we have enough of the real world in the rest of our media, whereas in fantasy almost anything goes and I love that. Personally, I want my fantasy to remain crazy. You know, that’s the point of it. I’ve got other, you know normal stuff, it’s called the real world and I try to spend as little time in it as possible, thank you very much. As a scientist, I love to watch fantasy that’s grounded itself in reality and tries to make its magic feel real. But sometimes you don’t want that. Sometimes you want the fantastical and based on the number of stories throughout history and around the world, perhaps there’s something in all of us that just wants an impossible gigantic flying lizard that breathes fire to be real. Just not near me, please. In this video I used some basic statistical techniques and analyzed scientific literature to apply real science to fantasy. I have some expertise in these fields, what with the master’s degree and the PhD, but you don’t have to spend eight years at university to learn how to use these skills and do this kind of analysis. If you found this video interesting then you might want to take a look at Brilliant is an educational website appropriate for students from age 12 to age 200 who would like to learn by getting their hands dirty and solving problems. What I did in this video is an example of
how you learn on You learn a new idea or fact and apply your knowledge to some new situation. And just like in this video if you get that wrong, it’s absolutely fine. By making mistakes you allow yourself to improve. It highlights things that you might have misconceived or misremembered and allows you to improve your understanding. I can’t guarantee that your understanding will involve dragons however. The fastest way to learn a new skill is to simply try using it and learn from your mistakes in an intelligent way. You can use parts of brilliant for free, so there’s really no excuse to not check it out. And you can also get a premium account for either yourself or as a gift for a student you know. Which gives access to their fantastic guided courses. If you’re interested in getting a premium account then use the link in the description and the first 200 people to do so will get 20% off. Thank you so much for watching this video. It has been a real labor of love over the past couple of months. This channel has undergone something of a hiatus for a while and there is a vlog coming out very soon explaining why that is. No small part of it is this video which is probably the most ambitious video project I’ve ever done, so I do have to say a massive thank you to everyone who made it possible. Notably, Dr Evans, Alex. Thank you so much for being interviewed. If you are interested in biology definitely check out his twitter, there’ll be a link in the description, because he’s always tweeting about some really interesting stuff. And also, thank you to Ed Bell from Durrell for agreeing to talk to me. I already talked about Durrell’s work in the video. If you are interested in conservation and you think it’s worthwhile stopping species going extinct, then check out another link in the description to Durrell’s work and consider making a donation. They are one of the most important charities in the world. I also have to say huge thank you to Terps and Hulmes from the Yogscast. It was so much fun coming and filming in the studios with you guys and thank you for sharing your expertise. I learned an awful lot. I hope that it came across in the video, but these guys really do know their stuff. Yeah, it was great fun. I learned a lot on the trip. I hope that you guys have enjoyed watching the video. Links to their socials and to the Twitch for High Rollers, which I highly highly recommend, I’m a fan, are down there in the description. Okay, now this is turning into an Oscar acceptance speech. So basically thank you to everyone who made this video possible. Thank you you for watching and I will see you in the next one.


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