Inside Nature's Giants (2009) s01e01 Episode Script
The Elephant
Hidden inside every animal on earth is a remarkable story of survival.
Tonight, an extraordinary event's about to take place.
A team of leading experts are going to explore the inner workings of arguably one of the most iconic animals on earth - the elephant.
Contains scenes some viewers may find upsetting.
In this series you'll see natural history as you never seen it before - from the inside out.
Just as you lift the bonnet of a car to find out how it works, we'll delve under the skin of these magnificent beasts to look at their unique anatomy, and reveal the secrets of their evolutionary past.
Richard Dawkins will show how anatomy provides proof of natural selection.
Evolution produces almost perfect design, the illusion of design, it looks exactly as an engineer might have done it.
Biologist Simon Watts will see how his own body matches up to the animals' adaptations.
42 seconds, pretty feeble even by human standards.
And I'll be seeing these animals in action.
When they're moving, it almost seems like they're running in slow motion.
Join us as we go deep inside the elephant.
Welcome to the Royal Veterinary College just outside London.
Whenever a zoo animals dies, a post-mortem is carried out as a matter of course.
After a very brave fight against a chronic debilitating illness, this elephant was euthanized because her keepers and vets felt that they were no longer able to protect her quality of life.
Tonight, as well as trying to learn as much as possible from this elephant's tragic death, we also want to celebrate a life that's evolved over the last 55 million years.
The closer one looks at an elephant, the stranger and more alien it can seem.
Its legs are like tree-trunks, supporting the heaviest animal that walks the earth - it can weigh as much as a truck.
Its iconic flapping ears can grow to six feet, and its unique trunk is one of nature's masterpieces.
But strangely, the key to understanding the elephant is hidden inside its body - its guts.
And that's where our dissection begins.
We fully appreciate that you may be a tad apprehensive about what we're gonna show you tonight, but as scientists we are desperate to show you the kinds of things that you just don't normally see on traditional natural history programmes.
Before dissection can begin, we must release the gases that have built up inside.
HISSING Elephants' guts produce 2,000 litres of methane a day.
That's enough to fill a weather balloon.
Our audience are veterinary students.
They're behind glass not to protect them from the smell, but to prevent the spread of potentially dangerous pathogens.
It's also why we're all wearing protective suits.
Joy, from your point of view, obviously as a comparative anatomist, what's your area of interest in the elephant? My main area is to see how they've adapted to their environment.
It's hard to hear you on the basis of trying to it just shows you, though, how much gas builds up within 24 hours.
This is an herbivore and they generate a lot of gas because their gut is basically a big fermenting chamber, but now the additional gas of the post-mortem decomposition, so that's added to the volume that you're seeing in front of us here.
And on a comparative basis, obviously it is a mammal like us but, but we're expecting to see some pretty extreme biological engineering in here? Absolutely.
22 years ago, I trained here as a vet.
I was one of the students behind the glass, just like them.
But in my entire career working with animals, I've never witnessed anything quite like this.
The sharpest knife at the college belongs to Richard Prior.
He works on most major dissections.
To gain access to the elephant's guts, Richard must first remove its legs.
While he's doing that, let me tell you a little bit more about Joy Reidenberg.
She loves gross anatomy and specialises in large animals.
She's probably been inside more whales than anyone else on the planet, and what never ceases to enthral her is comparing anatomy across the animal kingdom.
What's happened now is they've lifted the hind leg off and they've also lifted the front leg off so that we can get access into the abdominal and thoracic cavities in the animal.
This is the area where the shoulder blade was, and all of that has been pulled backwards so we have access to underneath where all the ribs are, and we should see the heart and the lungs.
On the other side, the hind leg has been lifted off.
What they're doing is taking the skin off so we can have access to the abdominal area where the intestines are.
I'm absolutely gobsmacked how heavy this skin is, it is amazing.
It's amazing.
In fact, you can almost not hold on to it, I mean it's difficult to carry the weight.
People see an elephant as such a large animal they assume it's a fat animal, but it's really not a fat animal.
And it looks fat because its got a very big abdomen full of fantastic its digestive system gives it that appearance, doesn't it? Which we're gonna look at.
Which we're gonna look at.
Which is the next part of the procedure.
Richard, all yours.
OK, we can see the ribs nicely there, can't we? You can see now that the body wall is actually made up of a number of muscle layers and you can see three of them here, three separate muscle layers.
The muscles running in different directions, to give that extra support so the muscles won't tear in any one direction, you've got that cross support.
Ah, here we are.
So, you're now into peritoneum.
Yeah.
You get an immediate sense now, having opened the abdominal wall, just how vast the digestive system is.
Can you stand back, please.
Look at it as it's coming out now, it's that, all of that you need to be able to fuel this massive animal.
Wow! That is incredibly big.
I don't think I expected to be that I did not expect it to be that big.
Again you can see the tension here, with lots of gas being produced and some liquid content as well, so we just need to relieve all that pressure.
Oof! Sorry, Mark.
You did that deliberately! What we're looking at here is the omentum which is a fine tissue that holds all the blood vessels that are wrapping around the gut in this area.
It has another function, which is if there's any damage to the wall of the intestine and there's a lesion, or a hole penetrating through, this can clamp down over the hole and stop anything leaking out and spreading around the rest of the body cavity.
Absolutely, it's such a beautiful tissue isn't it? Nature's band aid! Absolutely, absolutely.
With the guts released, the team can now start untangling the intestines.
It's still warm.
Let's take this one up this way.
It is important we try and separate this out so we can look at the different parts of this digestive system, to see how the elephant manages, from its plant food, to get what it needs to be able to fuel this massive body.
Isn't it incredible, to be able to fit all this lot on the floor inside that body cavity? It is absolutely extraordinary.
Take your pick, Richard.
We've got to try and orientate now.
This should be the rectum.
Yeah, that's the that's the rectum, so While the team gallantly try to sort out the orientation of the digestive system, let's take a look at this giant eating machine in action.
Earlier this year, I went out to South Africa to find out what elephants eat that actually requires such massive guts.
Park ranger Percy Ramagama has taken me as close to the elephants as is safely possible.
Listen to that - that's a whole bush gone over.
It's amazing, being this close, you can hear the start of digestion, the getting the food and ingesting it into the digestive system and you can hear how destructive that is, the crashing and crunching of branches as they move to take the food that they want.
It turns out elephants will eat practically anything.
No tree or bush is safe.
Bark, wood, roots, even the soil they grow in.
All are on the menu.
But it's so poorly nutritious, they need to eat a lot.
In 20 days, they will eat their entire body weight in plants, hence the need for big guts to process it all.
Let's go back there, the wind is stable now.
OK.
We need to move on because the wind's dropped and it's now going round in circles, so that puts us in a fairly vulnerable position.
Finally, we've managed to get the digestive system laid out.
Let me take you on a little journey that this elephant's food would go on when it's eating and when it was alive.
This elephant would be fed a mixture of hay, also things like fruits and so on, and obviously that would go in this end and be macerated and chewed up by its incredible teeth, which we'll look at later.
It would then end up here, a sack which is the stomach, very similar to our stomach, that's connected directly to all this pipe work here that is the small intestine.
This is where the kind of easy stuff to digest is digested to get lots of energy out of its food, that's quick and easy to harness.
Then, though, the small intestine goes round here, down this pipe here and joins this massive bag here, which is called the cecum.
We have a cecum, we have a little appendix next to it which is relatively small because we don't digest this kind of food, but this is the really important part of the elephant's digestive system, where fermentation goes on to extract goodness out of this incredibly rough plant material.
That goes on in the cecum which is then connected to this massive piece of pipe work which is the large intestine, where some more fermentation goes on, and the absorption of the goodness that the elephant's managed to get out of here.
Then, finally, when it gets down to the rectum, out it produces a fecal pellet.
Now look at this - they're not massively different, in terms of you can tease this apart and it's very familiar as what started in the front end.
It's not a brilliantly efficient digesture but it stays alive and it's able to fuel this huge massive animal, thanks to this part of its digestive system.
Welcome back.
We've been taking a close look at the elephant's amazing digestive system and we know it has to consume a huge amount of food to stay alive and fuel this big body.
As we dissect this animal, we want to piece together its evolutionary history.
How, for example, did the elephant's teeth adapt to cope with the coarse diet needed to fuel such a massive body? While Joy starts work on the jaw to find out, biologist Simon Watt is going to look at the difficulties faced by the elephant's ancestors as their bodies grew in size.
Just look at this skeleton, accounting for nearly 17% of the elephant's total body weight.
It's the heaviest of any land animal.
And it grew so big in order to house its massive guts, but that size produced a problem for evolution to overcome.
How do you reach food on the ground? There were different solutions on neighbouring branches of the tree of life.
23 million years ago, Gompotherium came up with one answer, increasing the length of its lower jaw to bring the mouth to the ground.
And Amebelodon modified its lower jaw to dig with its shovel-shaped tusks.
But this cumbersome lower jaw began to shrink on one branch of the tree of life, leaving behind a long nose to grub for food.
The result was a group of animals we know today as elephants.
To cope with so much rough, fibrous food, the elephant's mouth evolved in an extraordinary way.
OK, what we're looking at right now is the lower jaw of the elephant and right here is one of the large muscles that helps to close the lower jaw.
This muscle attaches at the corner and pulls all the way up to this bony process.
These are massive muscles and they generate a lot of heat because this animal is chewing all the time.
If we move down into this area and we remove the cheek, we'll be able to see the teeth of this animal, so let's go down and cut that off.
So here's the lower jaw.
This is all bone.
And now, as we reveal this area, we can see the teeth.
This is a lower tooth.
Here's the second lower tooth.
This is an upper tooth right here.
And so these are grinding against each other.
We can see much better if we look at it on a dry skull and Gerald has a dried elephant skull that we can look at.
Just explain, compared to us, and we have incisors, canines, pre-molars, molars.
What is this the equivalent of? This is a typical molar type of tooth of an elephant.
As you can see, this tooth is very long, much longer than is the case in many other mammals.
And you can see on the grinding surface here a lot of ridges, which are called lamellae.
We have one lamella here, one of this section and it was glued together with cement.
So you couldn't store six of these teeth in your skull from when you're born.
So you start off with a very small version of the tooth, this lamella.
As that grows, it grows bigger, longer and then glues them together in the jaw.
It's like a conveyor belt.
The elephant tooth conveyor belt starts at the back of the mouth, where new sections of tooth, lamellae, are constantly growing and pushing forwards.
As the front of the teeth wear out, the lamellae break off to be replaced by the ones behind them.
In this way, the teeth are constantly renewed to keep the elephant munching away.
Male elephants also have enormous canine teeth, their tusks.
These are used for fighting, foraging and digging up roots.
But where's the tusk in our female elephant? In a male, a tusk would emerge over here.
There's a flap right here, one on either side of the trunk.
You would see the big tooth, a big tusk sticking out here.
But it's always been assumed that females don't have it and we don't see anything, so it looks like she has no tusk.
But let's cut underneath and see whether or not she has no tusk.
So as we cut through this skin and and peel it back .
.
what we see is there actually is a tooth buried in here.
It's a very small tusk, and this very small tusk is only about that big.
It's projecting just a tiny bit, not enough to come out of this pocket, but it's definitely here.
The female tusk, or tush, as it's known, serves no purpose to the elephant.
But for males, it's a very different story.
For them, size is absolutely everything.
They've evolved such large tusks through sexual selection as a sign of the power and dominance of the bull.
But more recently, new evolutionary pressures have come to bear, as Richard Dawkins explains.
During the time when humans have been hunting elephants for ivory, there's a significant trend to get smaller tusks.
It looks as though what's happened is that poachers and legitimate hunters are all the time shooting the biggest tuskers in order to get the ivory, with the result that there was a massive selection pressure in favour of smaller tusks.
And so the average tusk size in elephants has been going down and down and down.
It's one of the spectacular examples of evolution happening before our very eyes, within living memory.
It can happen very, very fast.
The thing that staggers me is if this is ten kilograms and this is a small tusk, in an adult African male, you could have a tusk that's 100 kilos, ten times the weight of that, sticking way out.
Just the skull, with no flesh on it at all, could weigh one and a half tons.
But you need to have that strength in the skull to be able to support these massive tusks and house your huge, great, grinding teeth.
But if you had it on a long neck, you would never get your head off the gro Yes, that's true.
So instead, elephants support their massive head on a short neck.
But that produces another problem to overcome - reaching food on the ground.
As we've seen, evolution's solution is one of nature's great wonders.
The only limb of its kind - the trunk.
The trunk is an astonishingly versatile organ.
It is used for social purposes, for caresses, for greetings.
It's used for drinking, it's used for feeding.
You think about the problems of controlling the trunk, they are formidable.
We control our arm, we've got bones with muscles on and we can sort of see how, when you pull on the bone, it'll move in predictable ways.
The trunk doesn't have any bones, yet it manages to achieve the same kind of sensitivity of control.
How it achieves that control is the next revelation from the dissection.
What we've got here is the trunk of an Asian elephant.
It has a little finger at the end, that's unique to the Asian elephant.
An African elephant would have two dextrous fingers that can move in this area.
This finger can pick up very tiny objects, like a little peanut, and can move it around, bring it to its mouth.
So what we're going to do now is look at these muscles and also at the nasal passageway.
So Richard's gotta cut right over here in one of the passages, this is the right nasal passage.
And notice how deep down it is, there's quite a bit of muscle between the outside and where we're actually getting to the actual pipe, the actual breathing passageway or nostril.
So what we're looking at now is the tip of the nostrils.
Two nostrils at the end of the trunk.
And if we open one nostril here, this is the right nostril that's been cut.
We can see that passageway as it runs the entire length of the trunk, all the way up to the skull, where it enters into the skull.
So this is quite a lot of volume that this trunk is holding in here, and so we're going to look at the muscles.
So here are the muscles that are surrounding this trunk.
Some run along the length of the trunk, and as they run along the length of the trunk, those on top are the ones that are gonna lift the trunk up.
Those on the bottom, they're gonna lift the trunk down.
Muscles on the side can bring it to the right and left, and we also have muscles shown here in cross section that run circumferentially around the perimeter of the trunk.
And they can regulate the volume of that space by contracting it down.
And some that are radial that can pull out and open up that space to make it wider.
So how did the elephant get its trunk? Rudyard Kipling's version of events in Just So Stories is still enjoyed today, even by evolutionary biologists.
I love Kipling's Just So Stories, Oh, Best Beloved, but they are shockingly un-Darwinian, that the elephant got its trunk by being pulled by a crocodile.
Of course that isn't how it happened.
Natural selection works in a totally different way, so it's nothing like being pulled or pushed from outside.
As for what the actual selection pressure, what was the advantage of having a long trunk? One possibility is that it's something to do with drinking.
There were other reasons why elephants became big and tall, reaching the tops of trees, for example, like giraffes.
And like giraffes, that raises problems for drinking.
In the case of the giraffe, the whole head has to go down, and that means the head has to be small.
Elephants did it in a different way.
They keep the head large, which has some advantages, and they then have a long pipe leading out of the head which is the trunk.
Even though we now understand how the trunk works, its fine-tuned dexterity never ceases to amaze.
Elephants can throw darts.
And even paint pictures.
The trunk is a classic story of evolution in action, a perfect solution to the problems of growing so big.
But as the relevant grew bigger, the demands on other parts of its body grew greater.
It required a lot of oxygen to keep going, so the lungs became turbocharged to cope.
To see how they work, the dissection team are removing the ribs.
It's been a tough job because the lungs themselves are stuck to the ribcage.
I'm with Jon Cracknell, who's an experienced elephant vet.
If I saw that in a postmortem of any other mammal, I would think I was looking at the cause of death.
But this is normal for an elephant? This is completely normal.
This is the lungs here.
In most other mammal species, what you'd expect is a space between the ribs and the lung surface, the pleural space.
In the elephant, that's completely different.
You can see how it's attached to the ribs by this fibrous tissue which has been trimmed away elsewhere, and the fibrous tissues here, and as I lift it up you can see the lung tissue adhered to the underside, which would be attached to the rib, if you imagine that as my hand.
This occurs on the diaphragm on the ribs on the other side as well, and this is a hugely important difference in elephants that you don't see in other animals at all.
While the lungs of most animals float in a fluid-filled cavity just below the ribs, the elephant's lungs are physically glued to their ribs by a unique elastic connective tissue.
This in turn is attached to muscles which, when flexed, inflate the lungs.
No other mammal breathes like this.
So it must have evolved for a reason.
Why has the elephant ended up with this system? The honest answer - we don't know.
But there's a lot of theories.
One of the original ones in the '70s was that it was an adaption for being able to suck water up into the trunk.
If you try sticking two hoses up your own nose and sucking water up, it's very difficult.
However, new current thinking, looking at evolution, it looks like the elephant's adapted from marine mammals.
This is actually an adaptation to being able to swim and snorkel.
If you imagine when you're snorkelling, you're on the surface of the water and you've got this small tube about say long, and there's a bit of resistance there.
Imagine you're an elephant and you have a two-metre long trunk, and then you submerge much further down with a lot of water pressing on you.
You need a lot of force to be able to open that up, and I think this is what it's for.
It's thought elephants may have evolved reinforced lungs to withstand the extra pressure of snorkelling so deeply underwater.
In fact, we now believe that the elephants' ancestors relied on water to support their bodies.
Even today, elephants are at home in the water, thanks to an evolutionary adaptation in their distant past.
Our dissection team has been piecing together the inner workings of the biggest eating machine that walks the earth.
So far, we've seen how its trunk provides a constant stream of food, How its grinding teeth break it all down and how its guts expanded to cope with this relentless diet.
But being so big has its downsides.
On the inside, the guts generate vast amounts of heat as the food ferments.
While on the outside, the elephant's skin absorbs heat from the African sun.
It's a wonder they don't suffer meltdown, especially as elephants are not able to sweat.
Scientists in Africa are trying to work out what's going on.
I was looking forward to meeting one brave researcher who has managed to persuade elephants to swallow thermometers to see how they get rid of that heat.
It's a tiny little device that's called an R button.
So in here is the ability to actually there's an electronic thermometer essentially? Yes, a little thermostat that records temperature.
It's coated in wax and that's attached then to a 20cm ribbon so that we can find it easily in the bolus, in the dung.
And that's coated in a little bit of chocolate, so it's a little bit of a treat and they get a little chocolate truffle.
You haven't got it in the digestive system.
Not yet, no! Not yet, no! That's the bit I'm interested in! Stand up! Stand up! This is a really tricky technique to get this right cos they use water to get the elephant to start swallowing before they lob it in, so it gulps it down without realising it's there.
Well, that's the theory, anyway.
It went in, so hopefully now we'll just wait a couple of hours to a couple of days and, hopefully, it will come out in the faeces.
Good boy.
Over the next 24 hours, Nadine's equipment will work its way through the elephant's guts.
It'll record the elephant's body temperature every five minutes, day and night.
'Then, it's just a matter of recovering the equipment.
' I bet you need a nice fresh, steaming pile, don't you? Some here.
There we go.
Just sort of move it around and mush it around.
You're a tool using mammal, so you use a tool - very sensible! Yes.
Oh, hang on There.
Yes, yes, yes! SoThere we go.
Oh, do you know, that is steaming.
Yep.
Oh, that is still warm.
The thermometer reveals that the temperature inside the elephant remains surprisingly constant, at around 37 degrees, about the same as us.
But the elephant's outside temperature is a different story.
Using a thermal-imaging camera, the scientists measure skin temperatures of over 55 degrees during the day.
And their external temperature remains high during the cold nights to keep the elephant warm.
But just before dawn, their skin temperature drops dramatically.
Somehow, elephants are managing to dump their extra heat.
We know they don't sweat, so how are they doing it? The answer lies in a surprising part of their anatomy - their ears.
Joy is carrying out some very fine dissection work that will explain why elephants need such big ears.
If we open up the back of the ear, what we see are a whole bunch of blood vessels that are running here.
The elephant takes its hot blood, runs it into this ear, wherethe vessels are close to the surface, and then is able to radiate off that heat.
They can actually throw all of their blood from their entire body through this radiator in only about 20 minutes.
If they flap the ear back and forth and create an air current across it, that helps with the cooling.
It's a remarkably simple system.
Warm blood is pumped from the body into fine blood vessels near the surface of the skin of the ear.
Here, it's cooled down by the air before being pumped back into the body.
And by flapping its ears, the elephant increases the airflow to cool its blood more quickly.
Evolution has found an ingenious way of preventing this large animal from overheating.
As they became bigger, every part of their body had to adapt.
Their skeleton had to strengthen to cope with the extra weight.
As they grew, the legs evolved to be stiff, rigid columns supporting the body and allowing cooling air to pass beneath the belly.
The ribs and the chest became more barrel shaped to contain the massive guts, while the backbone grew to be quite robust, allowing it to hang the entire weight, the entire body, from it as a sort of arch, a bit like a suspension bridge.
The neck became shorter and shorter, moving the head closer to the front limbs and better able to support it when the head grew to be massive to deal with the volume of food that they were consuming.
TRUMPETING Elephants have enormous strength.
You provoke them at your peril.
TRUMPETING SHOUTING If panicked, they can run you down.
TRUMPETING How they support and move their massive weight is the next part of the puzzle for the dissection team.
Imagine how your legs and feet would feel if you were forced to stand up for the whole of your life.
Well, that's exactly what elephants have to do but here's something to reckon with.
This elephant is 40 times my weight, yet it's standing on a surface area that actually is only a few times bigger than the sole of my feet.
It's clear there's something very special about elephants' feet.
John Hutchinson is an expert in animal locomotion here at the Royal Veterinary College with an interest in elephants.
That's right, yes.
How do these incredible animals manage to cope with the challenge of carrying around so much weight just on four legs? Real bone, including elephant bone, is made of two kinds of materials.
It's a composite and we can do an interesting preparation here, where we soak a normal mammalian bone in acid and remove the mineral component from the bone, and that's what we've done.
What you'll see, if I apply just a little bit of load to this bone, is that it's remarkably compliant, it's remarkably bendy.
In contrast, this is the same bone from a similar species.
Bake it at really high temperatures and that will remove the organic material, so we're just left with the mineral component of bone.
And that bone is really, really brittle and you can see right here I can break it right away.
So an elephant, just like any other mammal or other vertebrate, has a skeleton made of both flexible and rigid mineral and organic materials.
OK, I understand that, but how are the bones arranged in the leg? Elephants support their weight by having large muscles, but also by having nice strong bones and by holding all that together in a pillar-like system.
You can see here for example, this is a cross section we've taken of our elephant tibia, or shank bone, and you can see it's quite solid here.
You can knock on it.
There's no marrow cavity in the middle, there's no empty space, and this is a very strong way of building a bone for handling compression - lots of weight on the bone.
Elephants can weigh to 12 tonnes and their legs have evolved to support that weight.
They spend their entire lives on their feet.
If they lie down, they can suffocate.
Yet, when they want to, elephants can move surprisingly fast, reaching speeds in excess of 20 miles an hour.
This produces potentially bone-shattering forces.
So, how do they manage to run? We all know that when animals like horses want to move fast, they change gait.
It's just like a gear change in a car.
It's a matter of efficiency.
Avignon here is going to demonstrate some of the different gaits.
At the moment, she's walking.
She's always got two or three of her feet on the ground at a time.
As she moves faster, she starts to trot.
Her legs are moving in diagonal pairs.
She's airborne for a brief moment.
If we speed up even more, we get to the canter.
Her feet are off the ground for even longer.
If she goes any faster, she'll eventually go to a gallop.
The question is, when elephants run, how do they change their gait? When an elephant wants to go quickly, it'll switch to its running gait which can go easily 10-15mph, maybe faster.
But John's sure that something else is going on.
So, borrowing a technique from the motion-picture industry, he films them with a high-speed camera.
By feeding the images into a computer, he creates a virtual elephant.
The results reveal that there is more to the elephant's foot than meets the eye.
It's using the limbs like pogo sticks to compress and rebound with each step and vault the animal upwards.
John, I'm really intrigued to find out a bit more about this pogo stick idea.
And you've come up with a way of demonstrating it using a hydraulic press, yeah? Yeah, it's just basically a car jack we've co-opted for use in our experiments.
So we'll be applying eventually quite a large load to this and it will show us how the elephant's foot responds to being loaded.
When an elephant stands, you've three tonnes over four feet, but if it was running, the forces on each foot as it lands will be considerably more than that? They can get up to one bodyweight on each foot at a time OK, so that's three tonnes over just the surface area here? Already it's beginning to compress a bit.
Pretty dramatic in the heel how that's starting to swell out sideways.
Yeah, that seems about the tension that I'd expect in a standing elephant.
Right, so four times that force when they're running? Uh-huh.
Wow.
And as it rolls over on to its toes again, if you release the pressure, it just feeds back in again and, actually, automatically lifts the whole limb? Yeah, there's some spring-like action to that, helping to push it forward.
I mean the mechanics of this inside, from an anatomy point of view, are we able to have a look at that? Yes.
What we have done over here, is taken a foot and run it through a band saw.
Just take me through This is the first time I've seen inside an elephant's foot, so take me through all the anatomy in here.
We've cut through the mid line, the third toe, the middle toe of the foot.
This is the tip of the toe with the toenail just a centimetre, half an inch, away from the bone.
These are toe bones coming up, so the elephant's standing on its tiptoes.
How many digits are they standing on? They're standing on five toes.
So they are standing on five? Yes.
Yeah, exactly.
Just like all mammals, elephants have five toes.
In fact, the whole foot is remarkably similar to ours, right the way up to the ankle joint.
But it's beneath that joint, in the elephant's heel, where the magic lies.
What dominates the bottom of the foot is this massive structure which we call the fat pad, or the digital cushion.
And that's just like your heel pad.
If you touch your heel and push it, you'll feel a squishy tissue and that's what elephants have.
It's just like kind of walking on high-heeled shoes, except those high-heeled shoes are made of fat.
OK, so when it's walking then, it lands like that Yeah, it lands like that.
Well, about there Rolls over to a flat foot and keeps rolling.
Pushes off with the tips of its toes and the fat pad springs back.
As the heel spreads out, it absorbs the weight of the elephant and is primed to coil back like a spring, propelling the elephant forwards again.
It's a perfectly built shock absorber - trainers for elephants.
Evolution has certainly granted the elephant everything it needs to support its massive body but, of course, even the best designs can fail.
We know from this elephant's history that she was becoming increasingly lame.
In the final part, the team will investigate why.
The veterinary pathologists want to examine this elephant's joints to discover the cause of her discomfort.
These are the hamstring muscles I'm cutting through right now.
They suspect arthritis.
Get ready, Mark, this might be rather interesting.
Yeah? Can see something that looks suspicious.
Alun will be the best judge of it.
Alun Williams is one of the Royal Veterinary College's top pathologists.
His intuitive detective work helps him uncover mysterious illness and hidden trauma in animals from crocodiles to cats.
What do you make of this? What do you think of that joint fluid, before it disappears? What do you think of that joint fluid, before it disappears? Well, let's see how viscous it is.
When I'm lifting the syringe, I should have little strands of gloopy material sticking to the syringe and it's not quite.
So it's a little bit more fluid, it's not as viscous as it should be.
So part of the process of the degeneration and arthritis in the joint, you get more watery synovial fluid? Absolutely, the nature of the fluid changes.
Absolutely, the nature of the fluid changes.
Just take us through the bits that you're seeing here, cos it is dramatic.
We've got a nice smooth cartilage covering over the surface of the bone, you can just see the edge of it.
Now, cartilage doesn't really have any pain fibres in it, so when the joint moves, you don't feel any discomfort, it's there acting as a cushion on the end of the bone.
Now, in this elephant here, the cartilage has started to erode away quite dramatically.
And when the cartilage wears away, the bone underneath has pain fibres in it.
And so when the cartilage is lost, you're now rubbing bare bone on to another surface, and that hurts.
So in terms of, if you did the comparison with a human, if you had this kind of level of arthritis, it would be that painful, debilitating, it'd be artificial knee replacement? When it gets as bad as this, because we have erosions on both sides, so the outside and the inside parts of your knee, top and bottom, this is really quite severe and so this is just gonna get worse and worse and worse.
So we know this elephant has been in discomfort for a while.
This kind of evidence absolutely vindicates the decision by the vets and keepers to euthanize this poor elephant? The quality of life when you've got this degree of arthritis, is unbearable to think about.
I wouldn't like to think of the pain or discomfort this elephant had every time it tried to put a lot of weight through this leg.
We believe that towards the end of her life she was beginning to favour putting the weight on other legs rather than this one.
And at that point the vets and the keepers, really knew, you know, that the time had come.
The dissection has uncovered the pathology that led to this animal's death.
But it's also helped us appreciate the evolutionary history of this giant.
To get enough food, they need massive grinding teeth.
And to process it, an enormous gut.
A trunk to bring food to the mouth.
And radiator ears to keep cool.
And it's not just their anatomy that's been tuned by evolution.
They've had to change the way they live too.
To get enough food, elephants must roam vast distances.
They must remember their route and stay in touch with other family members.
To achieve this, they've developed brains larger than any other animal that walks the earth.
Exactly what they're thinking remains a mystery, but their behaviour suggests that they do have conscious thoughts.
Which may explain that most poignant behaviour, when they find the remains of other elephants.
They quietly caress the bones, sniffing them, turning them over as if trying to identify the dead.
Besides us, they are the only animals known to ritualise death.
Our post-mortem and dissection have confirmed beyond doubt that the very difficult decision that was taken to euthanize this elephant was absolutely the right call.
But they've also made a significant contribution to our scientific understanding of how these mighty animals are built.
There's no doubt that, as the largest land animals on earth, elephants push biological engineering to the absolute extreme.
I really hope that what we've shown you in this programme helps you appreciate even more just how amazing elephants are.
Next week, we'll be battling against the elements as the team dissect a whale.
It's an incredible hailstorm.
It hurts your face.
Joy will uncover its evolutionary past and we'll see why this animal's closest living relative is the hippo.
Red Bee Media Ltd
Tonight, an extraordinary event's about to take place.
A team of leading experts are going to explore the inner workings of arguably one of the most iconic animals on earth - the elephant.
Contains scenes some viewers may find upsetting.
In this series you'll see natural history as you never seen it before - from the inside out.
Just as you lift the bonnet of a car to find out how it works, we'll delve under the skin of these magnificent beasts to look at their unique anatomy, and reveal the secrets of their evolutionary past.
Richard Dawkins will show how anatomy provides proof of natural selection.
Evolution produces almost perfect design, the illusion of design, it looks exactly as an engineer might have done it.
Biologist Simon Watts will see how his own body matches up to the animals' adaptations.
42 seconds, pretty feeble even by human standards.
And I'll be seeing these animals in action.
When they're moving, it almost seems like they're running in slow motion.
Join us as we go deep inside the elephant.
Welcome to the Royal Veterinary College just outside London.
Whenever a zoo animals dies, a post-mortem is carried out as a matter of course.
After a very brave fight against a chronic debilitating illness, this elephant was euthanized because her keepers and vets felt that they were no longer able to protect her quality of life.
Tonight, as well as trying to learn as much as possible from this elephant's tragic death, we also want to celebrate a life that's evolved over the last 55 million years.
The closer one looks at an elephant, the stranger and more alien it can seem.
Its legs are like tree-trunks, supporting the heaviest animal that walks the earth - it can weigh as much as a truck.
Its iconic flapping ears can grow to six feet, and its unique trunk is one of nature's masterpieces.
But strangely, the key to understanding the elephant is hidden inside its body - its guts.
And that's where our dissection begins.
We fully appreciate that you may be a tad apprehensive about what we're gonna show you tonight, but as scientists we are desperate to show you the kinds of things that you just don't normally see on traditional natural history programmes.
Before dissection can begin, we must release the gases that have built up inside.
HISSING Elephants' guts produce 2,000 litres of methane a day.
That's enough to fill a weather balloon.
Our audience are veterinary students.
They're behind glass not to protect them from the smell, but to prevent the spread of potentially dangerous pathogens.
It's also why we're all wearing protective suits.
Joy, from your point of view, obviously as a comparative anatomist, what's your area of interest in the elephant? My main area is to see how they've adapted to their environment.
It's hard to hear you on the basis of trying to it just shows you, though, how much gas builds up within 24 hours.
This is an herbivore and they generate a lot of gas because their gut is basically a big fermenting chamber, but now the additional gas of the post-mortem decomposition, so that's added to the volume that you're seeing in front of us here.
And on a comparative basis, obviously it is a mammal like us but, but we're expecting to see some pretty extreme biological engineering in here? Absolutely.
22 years ago, I trained here as a vet.
I was one of the students behind the glass, just like them.
But in my entire career working with animals, I've never witnessed anything quite like this.
The sharpest knife at the college belongs to Richard Prior.
He works on most major dissections.
To gain access to the elephant's guts, Richard must first remove its legs.
While he's doing that, let me tell you a little bit more about Joy Reidenberg.
She loves gross anatomy and specialises in large animals.
She's probably been inside more whales than anyone else on the planet, and what never ceases to enthral her is comparing anatomy across the animal kingdom.
What's happened now is they've lifted the hind leg off and they've also lifted the front leg off so that we can get access into the abdominal and thoracic cavities in the animal.
This is the area where the shoulder blade was, and all of that has been pulled backwards so we have access to underneath where all the ribs are, and we should see the heart and the lungs.
On the other side, the hind leg has been lifted off.
What they're doing is taking the skin off so we can have access to the abdominal area where the intestines are.
I'm absolutely gobsmacked how heavy this skin is, it is amazing.
It's amazing.
In fact, you can almost not hold on to it, I mean it's difficult to carry the weight.
People see an elephant as such a large animal they assume it's a fat animal, but it's really not a fat animal.
And it looks fat because its got a very big abdomen full of fantastic its digestive system gives it that appearance, doesn't it? Which we're gonna look at.
Which we're gonna look at.
Which is the next part of the procedure.
Richard, all yours.
OK, we can see the ribs nicely there, can't we? You can see now that the body wall is actually made up of a number of muscle layers and you can see three of them here, three separate muscle layers.
The muscles running in different directions, to give that extra support so the muscles won't tear in any one direction, you've got that cross support.
Ah, here we are.
So, you're now into peritoneum.
Yeah.
You get an immediate sense now, having opened the abdominal wall, just how vast the digestive system is.
Can you stand back, please.
Look at it as it's coming out now, it's that, all of that you need to be able to fuel this massive animal.
Wow! That is incredibly big.
I don't think I expected to be that I did not expect it to be that big.
Again you can see the tension here, with lots of gas being produced and some liquid content as well, so we just need to relieve all that pressure.
Oof! Sorry, Mark.
You did that deliberately! What we're looking at here is the omentum which is a fine tissue that holds all the blood vessels that are wrapping around the gut in this area.
It has another function, which is if there's any damage to the wall of the intestine and there's a lesion, or a hole penetrating through, this can clamp down over the hole and stop anything leaking out and spreading around the rest of the body cavity.
Absolutely, it's such a beautiful tissue isn't it? Nature's band aid! Absolutely, absolutely.
With the guts released, the team can now start untangling the intestines.
It's still warm.
Let's take this one up this way.
It is important we try and separate this out so we can look at the different parts of this digestive system, to see how the elephant manages, from its plant food, to get what it needs to be able to fuel this massive body.
Isn't it incredible, to be able to fit all this lot on the floor inside that body cavity? It is absolutely extraordinary.
Take your pick, Richard.
We've got to try and orientate now.
This should be the rectum.
Yeah, that's the that's the rectum, so While the team gallantly try to sort out the orientation of the digestive system, let's take a look at this giant eating machine in action.
Earlier this year, I went out to South Africa to find out what elephants eat that actually requires such massive guts.
Park ranger Percy Ramagama has taken me as close to the elephants as is safely possible.
Listen to that - that's a whole bush gone over.
It's amazing, being this close, you can hear the start of digestion, the getting the food and ingesting it into the digestive system and you can hear how destructive that is, the crashing and crunching of branches as they move to take the food that they want.
It turns out elephants will eat practically anything.
No tree or bush is safe.
Bark, wood, roots, even the soil they grow in.
All are on the menu.
But it's so poorly nutritious, they need to eat a lot.
In 20 days, they will eat their entire body weight in plants, hence the need for big guts to process it all.
Let's go back there, the wind is stable now.
OK.
We need to move on because the wind's dropped and it's now going round in circles, so that puts us in a fairly vulnerable position.
Finally, we've managed to get the digestive system laid out.
Let me take you on a little journey that this elephant's food would go on when it's eating and when it was alive.
This elephant would be fed a mixture of hay, also things like fruits and so on, and obviously that would go in this end and be macerated and chewed up by its incredible teeth, which we'll look at later.
It would then end up here, a sack which is the stomach, very similar to our stomach, that's connected directly to all this pipe work here that is the small intestine.
This is where the kind of easy stuff to digest is digested to get lots of energy out of its food, that's quick and easy to harness.
Then, though, the small intestine goes round here, down this pipe here and joins this massive bag here, which is called the cecum.
We have a cecum, we have a little appendix next to it which is relatively small because we don't digest this kind of food, but this is the really important part of the elephant's digestive system, where fermentation goes on to extract goodness out of this incredibly rough plant material.
That goes on in the cecum which is then connected to this massive piece of pipe work which is the large intestine, where some more fermentation goes on, and the absorption of the goodness that the elephant's managed to get out of here.
Then, finally, when it gets down to the rectum, out it produces a fecal pellet.
Now look at this - they're not massively different, in terms of you can tease this apart and it's very familiar as what started in the front end.
It's not a brilliantly efficient digesture but it stays alive and it's able to fuel this huge massive animal, thanks to this part of its digestive system.
Welcome back.
We've been taking a close look at the elephant's amazing digestive system and we know it has to consume a huge amount of food to stay alive and fuel this big body.
As we dissect this animal, we want to piece together its evolutionary history.
How, for example, did the elephant's teeth adapt to cope with the coarse diet needed to fuel such a massive body? While Joy starts work on the jaw to find out, biologist Simon Watt is going to look at the difficulties faced by the elephant's ancestors as their bodies grew in size.
Just look at this skeleton, accounting for nearly 17% of the elephant's total body weight.
It's the heaviest of any land animal.
And it grew so big in order to house its massive guts, but that size produced a problem for evolution to overcome.
How do you reach food on the ground? There were different solutions on neighbouring branches of the tree of life.
23 million years ago, Gompotherium came up with one answer, increasing the length of its lower jaw to bring the mouth to the ground.
And Amebelodon modified its lower jaw to dig with its shovel-shaped tusks.
But this cumbersome lower jaw began to shrink on one branch of the tree of life, leaving behind a long nose to grub for food.
The result was a group of animals we know today as elephants.
To cope with so much rough, fibrous food, the elephant's mouth evolved in an extraordinary way.
OK, what we're looking at right now is the lower jaw of the elephant and right here is one of the large muscles that helps to close the lower jaw.
This muscle attaches at the corner and pulls all the way up to this bony process.
These are massive muscles and they generate a lot of heat because this animal is chewing all the time.
If we move down into this area and we remove the cheek, we'll be able to see the teeth of this animal, so let's go down and cut that off.
So here's the lower jaw.
This is all bone.
And now, as we reveal this area, we can see the teeth.
This is a lower tooth.
Here's the second lower tooth.
This is an upper tooth right here.
And so these are grinding against each other.
We can see much better if we look at it on a dry skull and Gerald has a dried elephant skull that we can look at.
Just explain, compared to us, and we have incisors, canines, pre-molars, molars.
What is this the equivalent of? This is a typical molar type of tooth of an elephant.
As you can see, this tooth is very long, much longer than is the case in many other mammals.
And you can see on the grinding surface here a lot of ridges, which are called lamellae.
We have one lamella here, one of this section and it was glued together with cement.
So you couldn't store six of these teeth in your skull from when you're born.
So you start off with a very small version of the tooth, this lamella.
As that grows, it grows bigger, longer and then glues them together in the jaw.
It's like a conveyor belt.
The elephant tooth conveyor belt starts at the back of the mouth, where new sections of tooth, lamellae, are constantly growing and pushing forwards.
As the front of the teeth wear out, the lamellae break off to be replaced by the ones behind them.
In this way, the teeth are constantly renewed to keep the elephant munching away.
Male elephants also have enormous canine teeth, their tusks.
These are used for fighting, foraging and digging up roots.
But where's the tusk in our female elephant? In a male, a tusk would emerge over here.
There's a flap right here, one on either side of the trunk.
You would see the big tooth, a big tusk sticking out here.
But it's always been assumed that females don't have it and we don't see anything, so it looks like she has no tusk.
But let's cut underneath and see whether or not she has no tusk.
So as we cut through this skin and and peel it back .
.
what we see is there actually is a tooth buried in here.
It's a very small tusk, and this very small tusk is only about that big.
It's projecting just a tiny bit, not enough to come out of this pocket, but it's definitely here.
The female tusk, or tush, as it's known, serves no purpose to the elephant.
But for males, it's a very different story.
For them, size is absolutely everything.
They've evolved such large tusks through sexual selection as a sign of the power and dominance of the bull.
But more recently, new evolutionary pressures have come to bear, as Richard Dawkins explains.
During the time when humans have been hunting elephants for ivory, there's a significant trend to get smaller tusks.
It looks as though what's happened is that poachers and legitimate hunters are all the time shooting the biggest tuskers in order to get the ivory, with the result that there was a massive selection pressure in favour of smaller tusks.
And so the average tusk size in elephants has been going down and down and down.
It's one of the spectacular examples of evolution happening before our very eyes, within living memory.
It can happen very, very fast.
The thing that staggers me is if this is ten kilograms and this is a small tusk, in an adult African male, you could have a tusk that's 100 kilos, ten times the weight of that, sticking way out.
Just the skull, with no flesh on it at all, could weigh one and a half tons.
But you need to have that strength in the skull to be able to support these massive tusks and house your huge, great, grinding teeth.
But if you had it on a long neck, you would never get your head off the gro Yes, that's true.
So instead, elephants support their massive head on a short neck.
But that produces another problem to overcome - reaching food on the ground.
As we've seen, evolution's solution is one of nature's great wonders.
The only limb of its kind - the trunk.
The trunk is an astonishingly versatile organ.
It is used for social purposes, for caresses, for greetings.
It's used for drinking, it's used for feeding.
You think about the problems of controlling the trunk, they are formidable.
We control our arm, we've got bones with muscles on and we can sort of see how, when you pull on the bone, it'll move in predictable ways.
The trunk doesn't have any bones, yet it manages to achieve the same kind of sensitivity of control.
How it achieves that control is the next revelation from the dissection.
What we've got here is the trunk of an Asian elephant.
It has a little finger at the end, that's unique to the Asian elephant.
An African elephant would have two dextrous fingers that can move in this area.
This finger can pick up very tiny objects, like a little peanut, and can move it around, bring it to its mouth.
So what we're going to do now is look at these muscles and also at the nasal passageway.
So Richard's gotta cut right over here in one of the passages, this is the right nasal passage.
And notice how deep down it is, there's quite a bit of muscle between the outside and where we're actually getting to the actual pipe, the actual breathing passageway or nostril.
So what we're looking at now is the tip of the nostrils.
Two nostrils at the end of the trunk.
And if we open one nostril here, this is the right nostril that's been cut.
We can see that passageway as it runs the entire length of the trunk, all the way up to the skull, where it enters into the skull.
So this is quite a lot of volume that this trunk is holding in here, and so we're going to look at the muscles.
So here are the muscles that are surrounding this trunk.
Some run along the length of the trunk, and as they run along the length of the trunk, those on top are the ones that are gonna lift the trunk up.
Those on the bottom, they're gonna lift the trunk down.
Muscles on the side can bring it to the right and left, and we also have muscles shown here in cross section that run circumferentially around the perimeter of the trunk.
And they can regulate the volume of that space by contracting it down.
And some that are radial that can pull out and open up that space to make it wider.
So how did the elephant get its trunk? Rudyard Kipling's version of events in Just So Stories is still enjoyed today, even by evolutionary biologists.
I love Kipling's Just So Stories, Oh, Best Beloved, but they are shockingly un-Darwinian, that the elephant got its trunk by being pulled by a crocodile.
Of course that isn't how it happened.
Natural selection works in a totally different way, so it's nothing like being pulled or pushed from outside.
As for what the actual selection pressure, what was the advantage of having a long trunk? One possibility is that it's something to do with drinking.
There were other reasons why elephants became big and tall, reaching the tops of trees, for example, like giraffes.
And like giraffes, that raises problems for drinking.
In the case of the giraffe, the whole head has to go down, and that means the head has to be small.
Elephants did it in a different way.
They keep the head large, which has some advantages, and they then have a long pipe leading out of the head which is the trunk.
Even though we now understand how the trunk works, its fine-tuned dexterity never ceases to amaze.
Elephants can throw darts.
And even paint pictures.
The trunk is a classic story of evolution in action, a perfect solution to the problems of growing so big.
But as the relevant grew bigger, the demands on other parts of its body grew greater.
It required a lot of oxygen to keep going, so the lungs became turbocharged to cope.
To see how they work, the dissection team are removing the ribs.
It's been a tough job because the lungs themselves are stuck to the ribcage.
I'm with Jon Cracknell, who's an experienced elephant vet.
If I saw that in a postmortem of any other mammal, I would think I was looking at the cause of death.
But this is normal for an elephant? This is completely normal.
This is the lungs here.
In most other mammal species, what you'd expect is a space between the ribs and the lung surface, the pleural space.
In the elephant, that's completely different.
You can see how it's attached to the ribs by this fibrous tissue which has been trimmed away elsewhere, and the fibrous tissues here, and as I lift it up you can see the lung tissue adhered to the underside, which would be attached to the rib, if you imagine that as my hand.
This occurs on the diaphragm on the ribs on the other side as well, and this is a hugely important difference in elephants that you don't see in other animals at all.
While the lungs of most animals float in a fluid-filled cavity just below the ribs, the elephant's lungs are physically glued to their ribs by a unique elastic connective tissue.
This in turn is attached to muscles which, when flexed, inflate the lungs.
No other mammal breathes like this.
So it must have evolved for a reason.
Why has the elephant ended up with this system? The honest answer - we don't know.
But there's a lot of theories.
One of the original ones in the '70s was that it was an adaption for being able to suck water up into the trunk.
If you try sticking two hoses up your own nose and sucking water up, it's very difficult.
However, new current thinking, looking at evolution, it looks like the elephant's adapted from marine mammals.
This is actually an adaptation to being able to swim and snorkel.
If you imagine when you're snorkelling, you're on the surface of the water and you've got this small tube about say long, and there's a bit of resistance there.
Imagine you're an elephant and you have a two-metre long trunk, and then you submerge much further down with a lot of water pressing on you.
You need a lot of force to be able to open that up, and I think this is what it's for.
It's thought elephants may have evolved reinforced lungs to withstand the extra pressure of snorkelling so deeply underwater.
In fact, we now believe that the elephants' ancestors relied on water to support their bodies.
Even today, elephants are at home in the water, thanks to an evolutionary adaptation in their distant past.
Our dissection team has been piecing together the inner workings of the biggest eating machine that walks the earth.
So far, we've seen how its trunk provides a constant stream of food, How its grinding teeth break it all down and how its guts expanded to cope with this relentless diet.
But being so big has its downsides.
On the inside, the guts generate vast amounts of heat as the food ferments.
While on the outside, the elephant's skin absorbs heat from the African sun.
It's a wonder they don't suffer meltdown, especially as elephants are not able to sweat.
Scientists in Africa are trying to work out what's going on.
I was looking forward to meeting one brave researcher who has managed to persuade elephants to swallow thermometers to see how they get rid of that heat.
It's a tiny little device that's called an R button.
So in here is the ability to actually there's an electronic thermometer essentially? Yes, a little thermostat that records temperature.
It's coated in wax and that's attached then to a 20cm ribbon so that we can find it easily in the bolus, in the dung.
And that's coated in a little bit of chocolate, so it's a little bit of a treat and they get a little chocolate truffle.
You haven't got it in the digestive system.
Not yet, no! Not yet, no! That's the bit I'm interested in! Stand up! Stand up! This is a really tricky technique to get this right cos they use water to get the elephant to start swallowing before they lob it in, so it gulps it down without realising it's there.
Well, that's the theory, anyway.
It went in, so hopefully now we'll just wait a couple of hours to a couple of days and, hopefully, it will come out in the faeces.
Good boy.
Over the next 24 hours, Nadine's equipment will work its way through the elephant's guts.
It'll record the elephant's body temperature every five minutes, day and night.
'Then, it's just a matter of recovering the equipment.
' I bet you need a nice fresh, steaming pile, don't you? Some here.
There we go.
Just sort of move it around and mush it around.
You're a tool using mammal, so you use a tool - very sensible! Yes.
Oh, hang on There.
Yes, yes, yes! SoThere we go.
Oh, do you know, that is steaming.
Yep.
Oh, that is still warm.
The thermometer reveals that the temperature inside the elephant remains surprisingly constant, at around 37 degrees, about the same as us.
But the elephant's outside temperature is a different story.
Using a thermal-imaging camera, the scientists measure skin temperatures of over 55 degrees during the day.
And their external temperature remains high during the cold nights to keep the elephant warm.
But just before dawn, their skin temperature drops dramatically.
Somehow, elephants are managing to dump their extra heat.
We know they don't sweat, so how are they doing it? The answer lies in a surprising part of their anatomy - their ears.
Joy is carrying out some very fine dissection work that will explain why elephants need such big ears.
If we open up the back of the ear, what we see are a whole bunch of blood vessels that are running here.
The elephant takes its hot blood, runs it into this ear, wherethe vessels are close to the surface, and then is able to radiate off that heat.
They can actually throw all of their blood from their entire body through this radiator in only about 20 minutes.
If they flap the ear back and forth and create an air current across it, that helps with the cooling.
It's a remarkably simple system.
Warm blood is pumped from the body into fine blood vessels near the surface of the skin of the ear.
Here, it's cooled down by the air before being pumped back into the body.
And by flapping its ears, the elephant increases the airflow to cool its blood more quickly.
Evolution has found an ingenious way of preventing this large animal from overheating.
As they became bigger, every part of their body had to adapt.
Their skeleton had to strengthen to cope with the extra weight.
As they grew, the legs evolved to be stiff, rigid columns supporting the body and allowing cooling air to pass beneath the belly.
The ribs and the chest became more barrel shaped to contain the massive guts, while the backbone grew to be quite robust, allowing it to hang the entire weight, the entire body, from it as a sort of arch, a bit like a suspension bridge.
The neck became shorter and shorter, moving the head closer to the front limbs and better able to support it when the head grew to be massive to deal with the volume of food that they were consuming.
TRUMPETING Elephants have enormous strength.
You provoke them at your peril.
TRUMPETING SHOUTING If panicked, they can run you down.
TRUMPETING How they support and move their massive weight is the next part of the puzzle for the dissection team.
Imagine how your legs and feet would feel if you were forced to stand up for the whole of your life.
Well, that's exactly what elephants have to do but here's something to reckon with.
This elephant is 40 times my weight, yet it's standing on a surface area that actually is only a few times bigger than the sole of my feet.
It's clear there's something very special about elephants' feet.
John Hutchinson is an expert in animal locomotion here at the Royal Veterinary College with an interest in elephants.
That's right, yes.
How do these incredible animals manage to cope with the challenge of carrying around so much weight just on four legs? Real bone, including elephant bone, is made of two kinds of materials.
It's a composite and we can do an interesting preparation here, where we soak a normal mammalian bone in acid and remove the mineral component from the bone, and that's what we've done.
What you'll see, if I apply just a little bit of load to this bone, is that it's remarkably compliant, it's remarkably bendy.
In contrast, this is the same bone from a similar species.
Bake it at really high temperatures and that will remove the organic material, so we're just left with the mineral component of bone.
And that bone is really, really brittle and you can see right here I can break it right away.
So an elephant, just like any other mammal or other vertebrate, has a skeleton made of both flexible and rigid mineral and organic materials.
OK, I understand that, but how are the bones arranged in the leg? Elephants support their weight by having large muscles, but also by having nice strong bones and by holding all that together in a pillar-like system.
You can see here for example, this is a cross section we've taken of our elephant tibia, or shank bone, and you can see it's quite solid here.
You can knock on it.
There's no marrow cavity in the middle, there's no empty space, and this is a very strong way of building a bone for handling compression - lots of weight on the bone.
Elephants can weigh to 12 tonnes and their legs have evolved to support that weight.
They spend their entire lives on their feet.
If they lie down, they can suffocate.
Yet, when they want to, elephants can move surprisingly fast, reaching speeds in excess of 20 miles an hour.
This produces potentially bone-shattering forces.
So, how do they manage to run? We all know that when animals like horses want to move fast, they change gait.
It's just like a gear change in a car.
It's a matter of efficiency.
Avignon here is going to demonstrate some of the different gaits.
At the moment, she's walking.
She's always got two or three of her feet on the ground at a time.
As she moves faster, she starts to trot.
Her legs are moving in diagonal pairs.
She's airborne for a brief moment.
If we speed up even more, we get to the canter.
Her feet are off the ground for even longer.
If she goes any faster, she'll eventually go to a gallop.
The question is, when elephants run, how do they change their gait? When an elephant wants to go quickly, it'll switch to its running gait which can go easily 10-15mph, maybe faster.
But John's sure that something else is going on.
So, borrowing a technique from the motion-picture industry, he films them with a high-speed camera.
By feeding the images into a computer, he creates a virtual elephant.
The results reveal that there is more to the elephant's foot than meets the eye.
It's using the limbs like pogo sticks to compress and rebound with each step and vault the animal upwards.
John, I'm really intrigued to find out a bit more about this pogo stick idea.
And you've come up with a way of demonstrating it using a hydraulic press, yeah? Yeah, it's just basically a car jack we've co-opted for use in our experiments.
So we'll be applying eventually quite a large load to this and it will show us how the elephant's foot responds to being loaded.
When an elephant stands, you've three tonnes over four feet, but if it was running, the forces on each foot as it lands will be considerably more than that? They can get up to one bodyweight on each foot at a time OK, so that's three tonnes over just the surface area here? Already it's beginning to compress a bit.
Pretty dramatic in the heel how that's starting to swell out sideways.
Yeah, that seems about the tension that I'd expect in a standing elephant.
Right, so four times that force when they're running? Uh-huh.
Wow.
And as it rolls over on to its toes again, if you release the pressure, it just feeds back in again and, actually, automatically lifts the whole limb? Yeah, there's some spring-like action to that, helping to push it forward.
I mean the mechanics of this inside, from an anatomy point of view, are we able to have a look at that? Yes.
What we have done over here, is taken a foot and run it through a band saw.
Just take me through This is the first time I've seen inside an elephant's foot, so take me through all the anatomy in here.
We've cut through the mid line, the third toe, the middle toe of the foot.
This is the tip of the toe with the toenail just a centimetre, half an inch, away from the bone.
These are toe bones coming up, so the elephant's standing on its tiptoes.
How many digits are they standing on? They're standing on five toes.
So they are standing on five? Yes.
Yeah, exactly.
Just like all mammals, elephants have five toes.
In fact, the whole foot is remarkably similar to ours, right the way up to the ankle joint.
But it's beneath that joint, in the elephant's heel, where the magic lies.
What dominates the bottom of the foot is this massive structure which we call the fat pad, or the digital cushion.
And that's just like your heel pad.
If you touch your heel and push it, you'll feel a squishy tissue and that's what elephants have.
It's just like kind of walking on high-heeled shoes, except those high-heeled shoes are made of fat.
OK, so when it's walking then, it lands like that Yeah, it lands like that.
Well, about there Rolls over to a flat foot and keeps rolling.
Pushes off with the tips of its toes and the fat pad springs back.
As the heel spreads out, it absorbs the weight of the elephant and is primed to coil back like a spring, propelling the elephant forwards again.
It's a perfectly built shock absorber - trainers for elephants.
Evolution has certainly granted the elephant everything it needs to support its massive body but, of course, even the best designs can fail.
We know from this elephant's history that she was becoming increasingly lame.
In the final part, the team will investigate why.
The veterinary pathologists want to examine this elephant's joints to discover the cause of her discomfort.
These are the hamstring muscles I'm cutting through right now.
They suspect arthritis.
Get ready, Mark, this might be rather interesting.
Yeah? Can see something that looks suspicious.
Alun will be the best judge of it.
Alun Williams is one of the Royal Veterinary College's top pathologists.
His intuitive detective work helps him uncover mysterious illness and hidden trauma in animals from crocodiles to cats.
What do you make of this? What do you think of that joint fluid, before it disappears? What do you think of that joint fluid, before it disappears? Well, let's see how viscous it is.
When I'm lifting the syringe, I should have little strands of gloopy material sticking to the syringe and it's not quite.
So it's a little bit more fluid, it's not as viscous as it should be.
So part of the process of the degeneration and arthritis in the joint, you get more watery synovial fluid? Absolutely, the nature of the fluid changes.
Absolutely, the nature of the fluid changes.
Just take us through the bits that you're seeing here, cos it is dramatic.
We've got a nice smooth cartilage covering over the surface of the bone, you can just see the edge of it.
Now, cartilage doesn't really have any pain fibres in it, so when the joint moves, you don't feel any discomfort, it's there acting as a cushion on the end of the bone.
Now, in this elephant here, the cartilage has started to erode away quite dramatically.
And when the cartilage wears away, the bone underneath has pain fibres in it.
And so when the cartilage is lost, you're now rubbing bare bone on to another surface, and that hurts.
So in terms of, if you did the comparison with a human, if you had this kind of level of arthritis, it would be that painful, debilitating, it'd be artificial knee replacement? When it gets as bad as this, because we have erosions on both sides, so the outside and the inside parts of your knee, top and bottom, this is really quite severe and so this is just gonna get worse and worse and worse.
So we know this elephant has been in discomfort for a while.
This kind of evidence absolutely vindicates the decision by the vets and keepers to euthanize this poor elephant? The quality of life when you've got this degree of arthritis, is unbearable to think about.
I wouldn't like to think of the pain or discomfort this elephant had every time it tried to put a lot of weight through this leg.
We believe that towards the end of her life she was beginning to favour putting the weight on other legs rather than this one.
And at that point the vets and the keepers, really knew, you know, that the time had come.
The dissection has uncovered the pathology that led to this animal's death.
But it's also helped us appreciate the evolutionary history of this giant.
To get enough food, they need massive grinding teeth.
And to process it, an enormous gut.
A trunk to bring food to the mouth.
And radiator ears to keep cool.
And it's not just their anatomy that's been tuned by evolution.
They've had to change the way they live too.
To get enough food, elephants must roam vast distances.
They must remember their route and stay in touch with other family members.
To achieve this, they've developed brains larger than any other animal that walks the earth.
Exactly what they're thinking remains a mystery, but their behaviour suggests that they do have conscious thoughts.
Which may explain that most poignant behaviour, when they find the remains of other elephants.
They quietly caress the bones, sniffing them, turning them over as if trying to identify the dead.
Besides us, they are the only animals known to ritualise death.
Our post-mortem and dissection have confirmed beyond doubt that the very difficult decision that was taken to euthanize this elephant was absolutely the right call.
But they've also made a significant contribution to our scientific understanding of how these mighty animals are built.
There's no doubt that, as the largest land animals on earth, elephants push biological engineering to the absolute extreme.
I really hope that what we've shown you in this programme helps you appreciate even more just how amazing elephants are.
Next week, we'll be battling against the elements as the team dissect a whale.
It's an incredible hailstorm.
It hurts your face.
Joy will uncover its evolutionary past and we'll see why this animal's closest living relative is the hippo.
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