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Of all the animals in the world, | 0:00:04 | 0:00:09 | |
there are some that really stand out. | 0:00:09 | 0:00:11 | |
Look at you. | 0:00:11 | 0:00:13 | |
'That we think are special.' | 0:00:13 | 0:00:16 | |
We find them undeniably, almost unbearably cute. | 0:00:16 | 0:00:22 | |
Millions of us watch these animals online. | 0:00:25 | 0:00:28 | |
But behind every feature we love so much - | 0:00:28 | 0:00:33 | |
that big round head... | 0:00:33 | 0:00:36 | |
PANDA CUB SNEEZES | 0:00:36 | 0:00:38 | |
FROG SQUEAKS | 0:00:38 | 0:00:40 | |
..surprising sounds... | 0:00:40 | 0:00:42 | |
You are super, super cool. | 0:00:42 | 0:00:45 | |
CHIMPANZEE LAUGHS | 0:00:45 | 0:00:46 | |
..or those wide eyes - | 0:00:46 | 0:00:49 | |
is a secret survival strategy. | 0:00:49 | 0:00:53 | |
CAT PURRS | 0:00:53 | 0:00:55 | |
I'm Gordon Buchanan. | 0:00:56 | 0:00:59 | |
I've filmed our favourite animals all over the world. | 0:00:59 | 0:01:03 | |
Now, I want to discover | 0:01:03 | 0:01:06 | |
the hidden biology of these animal superstars. | 0:01:06 | 0:01:09 | |
Whoa. | 0:01:09 | 0:01:11 | |
HE CHUCKLES | 0:01:11 | 0:01:13 | |
Why this sweet face hides a deadly secret... | 0:01:13 | 0:01:17 | |
HUMMINGBIRD SNORES | 0:01:17 | 0:01:19 | |
..why hummingbirds snore... | 0:01:19 | 0:01:22 | |
HUMMINGBIRD SNORES | 0:01:22 | 0:01:24 | |
..and penguins waddle. | 0:01:24 | 0:01:27 | |
PENGUIN SHRIEKS | 0:01:27 | 0:01:29 | |
Behind every appealing animal | 0:01:31 | 0:01:34 | |
is an incredible story. | 0:01:34 | 0:01:37 | |
And I'm going to reveal their secrets. | 0:01:38 | 0:01:41 | |
If you took a poll of the top 20 animals on the planet, | 0:01:52 | 0:01:55 | |
I reckon these guys would be right at the top. | 0:01:55 | 0:01:58 | |
They are fantastic, those enormous ears, their trunks, beautiful eyes. | 0:01:58 | 0:02:03 | |
I just love them. | 0:02:04 | 0:02:06 | |
But we've all got our own favourites, | 0:02:08 | 0:02:10 | |
animals we find irresistibly appealing. | 0:02:10 | 0:02:14 | |
Hello. How you doing? | 0:02:14 | 0:02:17 | |
Sometimes we fall for the sounds they make. | 0:02:17 | 0:02:20 | |
Is that an invitation for me to tickle you? | 0:02:20 | 0:02:23 | |
It is, it is. | 0:02:23 | 0:02:25 | |
Others move in ways that delight us. | 0:02:25 | 0:02:29 | |
But often it's simply the way an animal looks | 0:02:31 | 0:02:35 | |
that makes it so compelling. | 0:02:35 | 0:02:38 | |
And they don't come much better looking than the iconic giant panda. | 0:02:40 | 0:02:48 | |
Famous as a symbol for conservation... | 0:02:51 | 0:02:55 | |
and for its sneeze. | 0:02:55 | 0:02:58 | |
PANDA CUB SNEEZES | 0:03:00 | 0:03:01 | |
Maybe you were one of the 200 million people | 0:03:01 | 0:03:04 | |
that watched this online. | 0:03:04 | 0:03:07 | |
PANDA CUB SNEEZES | 0:03:07 | 0:03:08 | |
Our monochrome love affair began in the 1970s | 0:03:10 | 0:03:14 | |
when China gave the first pandas to the Smithsonian Zoo. | 0:03:14 | 0:03:19 | |
And just last year, | 0:03:20 | 0:03:22 | |
their newest baby had over two million visitors, | 0:03:22 | 0:03:27 | |
all desperate to get a glimpse. | 0:03:27 | 0:03:31 | |
I've come to meet the little crowd-pleaser. | 0:03:33 | 0:03:37 | |
Hello, Bao Bao. | 0:03:39 | 0:03:41 | |
You really are the most adorable panda in the world. | 0:03:42 | 0:03:49 | |
Pandas really have to be one of the most recognisable animals | 0:03:51 | 0:03:55 | |
on the planet and arguably one of the best-loved. | 0:03:55 | 0:03:59 | |
They are an extraordinarily good-looking animal. | 0:03:59 | 0:04:04 | |
Now, pandas aren't the biggest of bears. | 0:04:06 | 0:04:08 | |
If you want overall size, | 0:04:08 | 0:04:10 | |
you have to look at brown bears or polar bears, | 0:04:10 | 0:04:14 | |
but look at the size of that head. | 0:04:14 | 0:04:17 | |
It is much bigger, much rounder than that of any other bear | 0:04:17 | 0:04:23 | |
and it's that beautiful big face that really | 0:04:23 | 0:04:26 | |
stops them looking like a predator. | 0:04:26 | 0:04:30 | |
Makes them look less threatening | 0:04:30 | 0:04:33 | |
and when you look into the face of a panda, | 0:04:33 | 0:04:35 | |
you don't feel any threat at all. | 0:04:35 | 0:04:38 | |
It's her beautiful face that makes little Bao Bao so appealing. | 0:04:45 | 0:04:52 | |
But why is it proportionally so much bigger | 0:04:52 | 0:04:55 | |
and rounder than other bear cubs? | 0:04:55 | 0:04:58 | |
Pandas are classed as carnivores. | 0:05:01 | 0:05:05 | |
They have the teeth and claws of meat-eaters | 0:05:05 | 0:05:09 | |
but they don't act like carnivores. | 0:05:09 | 0:05:11 | |
Around five million years ago, | 0:05:14 | 0:05:17 | |
pandas actually lost the taste for meat. | 0:05:17 | 0:05:20 | |
They switched to the food source that was most abundant. | 0:05:22 | 0:05:27 | |
A sensible choice you'd think, | 0:05:30 | 0:05:32 | |
except a stick of bamboo has barely any calories. | 0:05:32 | 0:05:38 | |
Especially compared with a hunk of red meat. | 0:05:38 | 0:05:42 | |
So, the panda is a carnivore that has gone vegetarian | 0:05:48 | 0:05:53 | |
and it has chosen one of THE toughest food sources around, | 0:05:53 | 0:05:56 | |
this stuff, bamboo. | 0:05:56 | 0:05:58 | |
They don't just eat these nice leaves, | 0:05:58 | 0:06:02 | |
which... | 0:06:02 | 0:06:04 | |
urgh, to me, pretty unappetising. | 0:06:04 | 0:06:06 | |
They will grind and pulverise even the thickest stems. | 0:06:06 | 0:06:11 | |
Oh, my goodness. | 0:06:11 | 0:06:13 | |
You get into this stuff, look at all those splinters. | 0:06:13 | 0:06:18 | |
A bear like the highly carnivorous polar bear can survive for days | 0:06:18 | 0:06:22 | |
and days on a single kill, but for a panda, | 0:06:22 | 0:06:24 | |
to get enough calories to survive just eating this, | 0:06:24 | 0:06:28 | |
they have to eat for, wait for this, 16 hours a day. | 0:06:28 | 0:06:33 | |
Breakfast, lunch and dinner is bamboo. | 0:06:33 | 0:06:37 | |
So to cope with the challenges of a bamboo diet, | 0:06:39 | 0:06:41 | |
the panda's body has had to change, adapt and evolve to deal with it. | 0:06:41 | 0:06:46 | |
Their stomach lining has grown thicker | 0:06:46 | 0:06:48 | |
to deal with all those splinters. | 0:06:48 | 0:06:51 | |
But it's the skull that has changed most dramatically. | 0:06:53 | 0:06:57 | |
Just looking at this skull, you can see that it's unlike | 0:06:59 | 0:07:02 | |
the skull of any other bear. | 0:07:02 | 0:07:04 | |
The bone itself is much denser, thicker and wider | 0:07:04 | 0:07:08 | |
and that allows these huge jaw muscles to attach. | 0:07:08 | 0:07:12 | |
This gives the panda a stronger bite force than a polar bear. | 0:07:13 | 0:07:19 | |
And it's this bamboo diet that has created this massive head, | 0:07:21 | 0:07:25 | |
a massive head that has such an extraordinary appeal for us. | 0:07:25 | 0:07:31 | |
The irony is, when covered with fur, | 0:07:34 | 0:07:39 | |
this mass of muscle and bone | 0:07:39 | 0:07:42 | |
looks like a teddy bear. | 0:07:42 | 0:07:45 | |
And Bao Bao's markings only make her more appealing. | 0:07:49 | 0:07:53 | |
In the wild, the eye-catching black and white | 0:08:00 | 0:08:04 | |
actually breaks up the panda's silhouette in the snowy forest... | 0:08:04 | 0:08:08 | |
..and makes the eyes look bigger, | 0:08:09 | 0:08:12 | |
more threatening to rivals and predators. | 0:08:12 | 0:08:15 | |
But the illusion has the complete opposite effect on us. | 0:08:17 | 0:08:22 | |
So, why have we fallen for these oversized features? | 0:08:25 | 0:08:29 | |
Well, bizarrely, it's all down to our own biology. | 0:08:31 | 0:08:37 | |
Big eyes trigger exactly the same emotional response in us | 0:08:39 | 0:08:44 | |
as when we see the panda's oversized head and that's really | 0:08:44 | 0:08:48 | |
because of the way that we respond when we see our own babies. | 0:08:48 | 0:08:52 | |
We're all born with these big heads and big eyes | 0:08:52 | 0:08:55 | |
and when we see those features, | 0:08:55 | 0:08:58 | |
our nurturing, caring instincts spring into action. | 0:08:58 | 0:09:03 | |
At the sight of Bao Bao's big baby-like head, | 0:09:04 | 0:09:08 | |
blood rushes to our midbrain - | 0:09:08 | 0:09:13 | |
part of the brain's "pleasure centre". | 0:09:13 | 0:09:16 | |
A flood of dopamine is released, | 0:09:18 | 0:09:22 | |
one of the hormones produced when we fall in love. | 0:09:22 | 0:09:26 | |
This chemical reaction creates emotions, | 0:09:27 | 0:09:32 | |
it's what makes us go all gooey. | 0:09:32 | 0:09:35 | |
Psychologists call it the "cute response" | 0:09:37 | 0:09:40 | |
and the "cute response" is so powerful, primitive and deep-rooted | 0:09:40 | 0:09:45 | |
that it can be triggered when we see those features in other species, | 0:09:45 | 0:09:50 | |
in animals. | 0:09:50 | 0:09:51 | |
Our love of the panda is down to our evolutionary hardwiring. | 0:09:51 | 0:09:57 | |
We just can't help it. | 0:09:57 | 0:10:00 | |
The power of the cute response | 0:10:14 | 0:10:16 | |
was perfectly demonstrated a few years ago... | 0:10:16 | 0:10:20 | |
..when a funny little creature grabbed global attention. | 0:10:21 | 0:10:25 | |
But I warn you, | 0:10:27 | 0:10:28 | |
it's not as sweet a story as it seems. | 0:10:28 | 0:10:33 | |
A video of a ticklish slow loris took the internet by storm. | 0:10:35 | 0:10:41 | |
WOMAN LAUGHS | 0:10:41 | 0:10:44 | |
Six million hits. | 0:10:44 | 0:10:46 | |
We couldn't get enough of this wide-eyed little gremlin. | 0:10:48 | 0:10:54 | |
For loris expert Anna Nekaris, | 0:10:57 | 0:11:00 | |
the overnight celebrity came as a bit of a shock. | 0:11:00 | 0:11:04 | |
Slow lorises are very rare in the wild and so | 0:11:05 | 0:11:08 | |
until about ten years ago, hardly anyone had heard of a slow loris | 0:11:08 | 0:11:11 | |
and then they became one of the most popular animals on the internet. | 0:11:11 | 0:11:15 | |
For many people, a slow loris is a quintessentially cute animal. | 0:11:15 | 0:11:20 | |
Its head is like a little round ball on top of a round body | 0:11:22 | 0:11:25 | |
and it's just got a really, sweet, innocent, cute face. | 0:11:26 | 0:11:30 | |
But like the panda, | 0:11:32 | 0:11:34 | |
it's the loris' biggest feature that makes it so appealing. | 0:11:34 | 0:11:39 | |
Its huge eyes. | 0:11:41 | 0:11:44 | |
They send our cute response into overdrive. | 0:11:46 | 0:11:52 | |
But it's in the wild that the true purpose of those incredible eyes | 0:12:01 | 0:12:07 | |
and the dark side of the sweet little loris is revealed. | 0:12:07 | 0:12:12 | |
Lorises are nocturnal. | 0:12:15 | 0:12:18 | |
In the dark, their huge pupils dilate wide. | 0:12:20 | 0:12:25 | |
This allows all available light to pass straight into the eye. | 0:12:26 | 0:12:31 | |
It gives them excellent vision even in the faintest of starlight, | 0:12:33 | 0:12:39 | |
which they use to stalk... | 0:12:39 | 0:12:42 | |
..and catch prey. | 0:12:43 | 0:12:46 | |
They may look really cute but when they grab their prey, | 0:12:56 | 0:13:00 | |
they're very vicious and the first thing they do is shred its head off, | 0:13:00 | 0:13:04 | |
and very proudly they lick it like a little lollipop | 0:13:04 | 0:13:07 | |
and eat the entire thing, all the wings, all the bones. | 0:13:07 | 0:13:10 | |
And their appetite isn't limited to insects. | 0:13:10 | 0:13:14 | |
This loris has set its sights on a roosting bird. | 0:13:18 | 0:13:23 | |
If that isn't enough to put you off your dinner, | 0:13:28 | 0:13:31 | |
they have an even more unsavoury skill. | 0:13:31 | 0:13:35 | |
What strikes one most if you see a slow loris | 0:13:38 | 0:13:41 | |
is that they have a long back with a dark stripe | 0:13:41 | 0:13:44 | |
and when they climb they move like a snake, | 0:13:44 | 0:13:47 | |
their spine moves in an S-shape, and if you try to catch one, | 0:13:47 | 0:13:50 | |
they hiss at you just like a snake. | 0:13:50 | 0:13:53 | |
They raise their arms above their head | 0:13:53 | 0:13:55 | |
and they form a hood above their head, like a cobra. | 0:13:55 | 0:13:58 | |
Because the internet cutie | 0:14:00 | 0:14:03 | |
is the world's only venomous primate. | 0:14:03 | 0:14:07 | |
Lorises secrete an oil from their elbow which, | 0:14:12 | 0:14:16 | |
when mixed with their saliva, | 0:14:16 | 0:14:19 | |
creates a deadly cocktail. | 0:14:19 | 0:14:22 | |
We know people who've lost half a limb, who've lost fingers, | 0:14:22 | 0:14:25 | |
people who've nearly died and people who have died from their bite, | 0:14:25 | 0:14:29 | |
so it's an animal you don't want to mess with despite the fact | 0:14:29 | 0:14:32 | |
it looks so appealing. | 0:14:32 | 0:14:34 | |
So, probably best not to tickle one then. | 0:14:36 | 0:14:41 | |
In the case of the slow loris, | 0:14:43 | 0:14:45 | |
our instinctive cute response is actually misleading us. | 0:14:45 | 0:14:51 | |
We see those big eyes, we imagine the loris is completely harmless, | 0:14:51 | 0:14:55 | |
we want to care for it, we even want to own one as a pet. | 0:14:55 | 0:15:00 | |
And clearly as the world's only venomous primate, | 0:15:00 | 0:15:04 | |
it's not the best animal to have around the house. | 0:15:04 | 0:15:06 | |
It's illegal to buy lorises | 0:15:06 | 0:15:09 | |
but the demand is so high caused by these videos | 0:15:09 | 0:15:13 | |
that lorises have become extinct in many of their jungle habitats. | 0:15:13 | 0:15:17 | |
It's a cautionary tale that cute can be a curse. | 0:15:17 | 0:15:22 | |
Oversized heads and big round eyes | 0:15:28 | 0:15:33 | |
push our biological buttons. | 0:15:33 | 0:15:35 | |
But the power of the cute response doesn't stop there. | 0:15:37 | 0:15:41 | |
I'm on my way to meet another animal favourite that proves that | 0:15:47 | 0:15:53 | |
almost any feature can be a trigger as long as it's big enough. | 0:15:53 | 0:15:58 | |
This is a fennec, | 0:16:05 | 0:16:08 | |
smallest member of the fox family, | 0:16:08 | 0:16:12 | |
weighing less than a bag of sugar. | 0:16:12 | 0:16:15 | |
But it's not its size | 0:16:16 | 0:16:18 | |
that's made the fennec famous. | 0:16:18 | 0:16:21 | |
Those are. | 0:16:22 | 0:16:24 | |
This little guy has the largest ear-to-body ratio of any carnivore. | 0:16:25 | 0:16:32 | |
Have a look at those ears. | 0:16:35 | 0:16:37 | |
They are phenomenal, completely over-sized. | 0:16:37 | 0:16:42 | |
Don't get me wrong, I'm a big fan of all foxes, | 0:16:42 | 0:16:45 | |
but those ears really are extra special. | 0:16:45 | 0:16:50 | |
Hello. How you doing? | 0:16:50 | 0:16:53 | |
And you see, as he's standing there, the ears are constantly rotating. | 0:16:55 | 0:17:01 | |
Twitching, just drinking up every single sound. | 0:17:01 | 0:17:06 | |
He's showing off his specialist skill. | 0:17:08 | 0:17:11 | |
And fennec foxes are incredibly sweet-looking | 0:17:14 | 0:17:18 | |
but they're also a very efficient hunter | 0:17:18 | 0:17:22 | |
and those ears are the tools of their trade. | 0:17:22 | 0:17:27 | |
Fennec foxes live out in the shifting sands of the Sahara. | 0:17:41 | 0:17:46 | |
In miles of open desert, | 0:17:48 | 0:17:50 | |
finding anything to eat can be difficult. | 0:17:50 | 0:17:54 | |
A game of hide and seek. | 0:17:58 | 0:18:01 | |
But fennecs have two unfair advantages. | 0:18:04 | 0:18:10 | |
Those huge ears act like amplifiers - | 0:18:16 | 0:18:19 | |
they gather all the sound | 0:18:19 | 0:18:21 | |
and channel it towards their inner ear. | 0:18:21 | 0:18:24 | |
Their hearing is so pin-sharp, | 0:18:24 | 0:18:27 | |
he can hear things that I can't hear and it's said that they can | 0:18:27 | 0:18:31 | |
hear a mouse's heartbeat underneath the sand. | 0:18:31 | 0:18:35 | |
Quite incredible. | 0:18:36 | 0:18:38 | |
OK, perhaps you might expect excellent hearing | 0:18:41 | 0:18:45 | |
from a set of ears that big. | 0:18:45 | 0:18:47 | |
But they have another, even more specialised role. | 0:18:47 | 0:18:52 | |
It's not unusual for the temperature to reach 50 degrees in the Sahara. | 0:18:54 | 0:19:01 | |
Too hot for most small mammals. | 0:19:01 | 0:19:05 | |
But the fennec fox is different, aren't you? | 0:19:07 | 0:19:11 | |
You can actually see when I hold him against the light, | 0:19:11 | 0:19:14 | |
you can see the blood vessels through his ear. | 0:19:14 | 0:19:17 | |
The skin is so thin that the heat from the blood is lost | 0:19:17 | 0:19:21 | |
into the air, and this cooling of the blood allows him to keep | 0:19:21 | 0:19:26 | |
his core temperature at a safe level. | 0:19:26 | 0:19:29 | |
It's what keeps him alive. | 0:19:29 | 0:19:31 | |
So, in fact, each ear is a radiator, | 0:19:33 | 0:19:37 | |
which is a critical survival tool | 0:19:37 | 0:19:40 | |
for this fantastic desert-dwelling animal. | 0:19:40 | 0:19:44 | |
Facial features are clearly a key factor in | 0:19:50 | 0:19:54 | |
deciding which animals we find cuter than others. | 0:19:54 | 0:19:58 | |
But there's one last physical attribute | 0:20:01 | 0:20:05 | |
that tops them all. | 0:20:05 | 0:20:07 | |
An animal can have the biggest eyes, | 0:20:08 | 0:20:12 | |
roundest face, | 0:20:12 | 0:20:14 | |
but if it's not furry, | 0:20:14 | 0:20:17 | |
then forget it. | 0:20:17 | 0:20:19 | |
The word "fluffy" gets over 20,000 hits on search engines every week. | 0:20:20 | 0:20:27 | |
The furrier the animal, the better. | 0:20:29 | 0:20:33 | |
Which brings me to America's west coast. | 0:20:34 | 0:20:39 | |
We associate fur with comfort, softness and warmth | 0:20:42 | 0:20:45 | |
and it's no surprise really that the animals with most fur | 0:20:45 | 0:20:49 | |
live in cold places, so why then am I here in California? | 0:20:49 | 0:20:54 | |
Well, the answer to that is | 0:20:54 | 0:20:55 | |
that the furriest animal on the planet lives just out there. | 0:20:55 | 0:21:00 | |
Whoa! | 0:21:21 | 0:21:22 | |
HE CHUCKLES | 0:21:22 | 0:21:23 | |
OK, OK, there we go. | 0:21:24 | 0:21:27 | |
Just in front of me, I can see the faces of what I'm after - | 0:21:27 | 0:21:33 | |
sea otters. | 0:21:33 | 0:21:35 | |
They have to be the most charming animal on the water. | 0:21:38 | 0:21:42 | |
I mean just look at them, see that lovely round face, | 0:21:42 | 0:21:45 | |
long whiskers. | 0:21:45 | 0:21:48 | |
That one's looking a bit slick with all the water | 0:21:48 | 0:21:50 | |
and there's another one that's fluffing itself up a bit. | 0:21:50 | 0:21:56 | |
I've got round about five million hairs on my body, | 0:21:56 | 0:22:01 | |
a sea otter has up to 800 million hairs on its body. | 0:22:01 | 0:22:07 | |
That's round about one million hairs per every square inch. | 0:22:07 | 0:22:11 | |
That is an astonishing amount of hair | 0:22:11 | 0:22:14 | |
and that's what makes sea otters the furriest animal on the planet. | 0:22:14 | 0:22:20 | |
There are 12 other species of otter around the world, | 0:22:26 | 0:22:31 | |
all with impressive fur. | 0:22:31 | 0:22:34 | |
OTTERS SQUEAK | 0:22:34 | 0:22:36 | |
But it's not nearly as dense | 0:22:39 | 0:22:42 | |
as their Californian cousins. | 0:22:42 | 0:22:46 | |
So just why is a sea otter | 0:22:46 | 0:22:49 | |
so furry? | 0:22:49 | 0:22:51 | |
Sea otters spend 95% of their lives in the water. | 0:22:55 | 0:22:59 | |
The ambient temperature is really quite warm | 0:22:59 | 0:23:01 | |
but the water itself, quite chilly, maybe round about 10 degrees. | 0:23:01 | 0:23:06 | |
If I fell in there, I probably wouldn't last that long. | 0:23:06 | 0:23:10 | |
Other sea creatures like sea lions, walruses, they've got blubber, | 0:23:10 | 0:23:16 | |
it's this thermal layer that protects their bodies. | 0:23:16 | 0:23:19 | |
Sea otters don't have the luxury of blubber, | 0:23:19 | 0:23:22 | |
but what they do have is fur, lots and lots of fur. | 0:23:22 | 0:23:27 | |
What we see are the long, tough guard hairs. | 0:23:29 | 0:23:32 | |
They provide a barrier but aren't completely waterproof. | 0:23:33 | 0:23:38 | |
Below is the otter's secret weapon. | 0:23:40 | 0:23:44 | |
A dense, soft underfur. | 0:23:44 | 0:23:49 | |
By rolling, rubbing and fluffing, | 0:23:50 | 0:23:54 | |
they push and trap air in between their fur fibres... | 0:23:54 | 0:23:58 | |
..which stops cold water ever reaching their skin. | 0:24:02 | 0:24:07 | |
But a sea otter's coat is more than just a dry suit. | 0:24:07 | 0:24:11 | |
It plays another fundamental role in their survival out at sea. | 0:24:11 | 0:24:17 | |
Sea otters are the most recently evolved marine mammal | 0:24:19 | 0:24:22 | |
and so they're not as fast as seals and sea lions | 0:24:22 | 0:24:25 | |
in terms of their ability to catch, you know, swimming fish. | 0:24:25 | 0:24:28 | |
Here in California, | 0:24:28 | 0:24:29 | |
they eat somewhere between 60 and 65 different species of prey items. | 0:24:29 | 0:24:33 | |
Typically crab, sea urchin, clam, mussel. | 0:24:33 | 0:24:39 | |
One of the adaptations that sea otters have for eating these | 0:24:39 | 0:24:41 | |
hard-shelled prey items is that they're tool users. | 0:24:41 | 0:24:44 | |
In some cases, | 0:24:44 | 0:24:45 | |
it's as simple as picking a rock up off the bottom of the ocean | 0:24:45 | 0:24:48 | |
and cracking clams or mussels. | 0:24:48 | 0:24:50 | |
But in other situations, it can be much more complex, you know, | 0:24:50 | 0:24:54 | |
we've seen otters that use things like bottles | 0:24:54 | 0:24:57 | |
as either a hammer or an anvil. | 0:24:57 | 0:24:59 | |
They might bang hard-shelled items against docks or boats. | 0:24:59 | 0:25:03 | |
Clever stuff. | 0:25:07 | 0:25:09 | |
But what's truly ingenious is how the fur comes in to play. | 0:25:10 | 0:25:14 | |
Using a tool in the middle of the ocean would be almost impossible | 0:25:16 | 0:25:21 | |
but all that trapped air makes the otter buoyant... | 0:25:21 | 0:25:25 | |
..and its stomach - | 0:25:27 | 0:25:28 | |
a floating work surface... | 0:25:28 | 0:25:31 | |
..from which they can consume up to 25% of their body weight in one day. | 0:25:33 | 0:25:40 | |
So, keeping this fantastically useful fur in tiptop condition | 0:25:42 | 0:25:46 | |
is crucial. | 0:25:46 | 0:25:48 | |
This pup will rely on mum to keep it warm, | 0:25:50 | 0:25:53 | |
dry and afloat until it learns to groom for itself. | 0:25:53 | 0:25:59 | |
But sometimes babies are orphaned... | 0:26:02 | 0:26:07 | |
or abandoned... | 0:26:07 | 0:26:09 | |
..and Karl and his team are called in. | 0:26:10 | 0:26:15 | |
At the Monterey Aquarium Sea Otter Programme, | 0:26:19 | 0:26:23 | |
Karl takes in pups as young as a day old. | 0:26:23 | 0:26:27 | |
When we get a stranded pup, all we're trying to do is basically | 0:26:31 | 0:26:34 | |
rehydrate the pups, start them on a bottle-feeding formula. | 0:26:34 | 0:26:38 | |
I should probably explain Karl's get-up. | 0:26:42 | 0:26:45 | |
It isn't safety gear, | 0:26:46 | 0:26:47 | |
this pup is about as dangerous as he looks. | 0:26:47 | 0:26:51 | |
The mask stops the pup thinking Karl is his mother. | 0:26:53 | 0:26:58 | |
If he's going to make it in the wild, | 0:27:00 | 0:27:02 | |
then it's best he doesn't get too attached. | 0:27:02 | 0:27:05 | |
To mimic the care that a pup would get from mum, | 0:27:08 | 0:27:12 | |
Karl and his team run an otter salon. | 0:27:12 | 0:27:15 | |
We start out with big broad towels | 0:27:18 | 0:27:20 | |
to essentially absorb most of the water. | 0:27:20 | 0:27:23 | |
And once the fur's sufficiently dry, we'll start incorporating brushes. | 0:27:23 | 0:27:28 | |
The brushes then allow us to | 0:27:29 | 0:27:31 | |
separate the fur and get the air flow down into the underfur. | 0:27:31 | 0:27:36 | |
Might take 10 or 15 minutes at a time. | 0:27:38 | 0:27:41 | |
That would be one grooming session and we're doing this | 0:27:41 | 0:27:43 | |
continuously throughout a 24-hour period with the pups. | 0:27:43 | 0:27:47 | |
It's a tough job, Karl, but someone's got to do it. | 0:27:47 | 0:27:52 | |
Their fur is so dense that they essentially float | 0:27:52 | 0:27:55 | |
like little corks at the surface of the water | 0:27:55 | 0:27:58 | |
and the water itself is not actually contacting the skin. | 0:27:58 | 0:28:00 | |
OTTER SQUEALS | 0:28:00 | 0:28:04 | |
By the time he's released back into the wild, | 0:28:08 | 0:28:11 | |
the pup will have learned all the skills he needs. | 0:28:11 | 0:28:14 | |
And his incredible fur will help him survive life | 0:28:16 | 0:28:19 | |
as a wild otter out in the bay. | 0:28:19 | 0:28:23 | |
For the panda, | 0:28:24 | 0:28:26 | |
loris, | 0:28:26 | 0:28:28 | |
fennec, | 0:28:28 | 0:28:29 | |
and sea otter, | 0:28:29 | 0:28:31 | |
supersized features are vital. | 0:28:31 | 0:28:35 | |
They're what allow them to live in very | 0:28:37 | 0:28:39 | |
different and challenging environments... | 0:28:39 | 0:28:42 | |
..to find food | 0:28:44 | 0:28:47 | |
and keep their body temperatures in check. | 0:28:47 | 0:28:49 | |
But appeal isn't always just about looks. | 0:28:51 | 0:28:54 | |
Sometimes it's the way an animal behaves | 0:28:54 | 0:28:58 | |
that makes it a favourite. | 0:28:58 | 0:29:00 | |
Elephants don't have big, forward-facing eyes, | 0:29:02 | 0:29:05 | |
they're not furry, they're hairy but not fluffy | 0:29:05 | 0:29:09 | |
and I'd argue with anyone that says this isn't cute, | 0:29:09 | 0:29:13 | |
so something else is going on here, something else is triggering | 0:29:13 | 0:29:16 | |
the cute response and I think a lot of it is to do with that nose. | 0:29:16 | 0:29:23 | |
Like any newborn, the first few months of an elephant's life | 0:29:31 | 0:29:35 | |
are a steep learning curve. | 0:29:35 | 0:29:36 | |
Walking is tricky enough. | 0:29:38 | 0:29:41 | |
But the extra appendage is even harder to get the hang of. | 0:29:43 | 0:29:48 | |
Elephants are born with short, stubby trunks. | 0:29:51 | 0:29:55 | |
But they elongate rapidly | 0:29:55 | 0:29:57 | |
over the first few weeks. | 0:29:57 | 0:30:00 | |
Mastering the movement | 0:30:03 | 0:30:05 | |
can be a minefield. | 0:30:05 | 0:30:07 | |
Baby elephants aren't born trunk-trained. | 0:30:15 | 0:30:17 | |
For the first few months, | 0:30:17 | 0:30:19 | |
an elephant's trunk has a mind all of its own | 0:30:19 | 0:30:23 | |
and to watch a baby elephant learn to use its trunk | 0:30:23 | 0:30:26 | |
has to be one of the most endearing things in nature. | 0:30:26 | 0:30:29 | |
So why is a trunk so hard to get to grips with? | 0:30:36 | 0:30:40 | |
Although we find the clumsiness endearing, | 0:30:43 | 0:30:46 | |
for the elephant, this period of development is fundamental | 0:30:46 | 0:30:51 | |
to their survival. | 0:30:51 | 0:30:53 | |
Because the trunk isn't just any old nose. | 0:30:55 | 0:31:00 | |
Elephants don't just use it to smell. | 0:31:00 | 0:31:03 | |
It's a straw... | 0:31:03 | 0:31:05 | |
..a hose... | 0:31:07 | 0:31:08 | |
..a snorkel... | 0:31:10 | 0:31:12 | |
and utensil. | 0:31:12 | 0:31:15 | |
While almost every other limb in the animal kingdom uses muscle | 0:31:23 | 0:31:28 | |
and bone together to create fine movement... | 0:31:28 | 0:31:31 | |
..an elephant's trunk is different. | 0:31:32 | 0:31:36 | |
It has no bones. | 0:31:36 | 0:31:38 | |
Instead muscles alone have to stretch, contract, | 0:31:40 | 0:31:45 | |
work with and against each other. | 0:31:45 | 0:31:49 | |
It's called a muscular hydrostat. | 0:31:50 | 0:31:53 | |
Your tongue is another example. | 0:31:54 | 0:31:56 | |
Tongues use eight muscles. | 0:31:58 | 0:32:01 | |
But, for a trunk to perform all the tasks an elephant needs, | 0:32:01 | 0:32:06 | |
well, it takes just a few more. | 0:32:06 | 0:32:10 | |
I've got just short of 650 muscles in my entire body. | 0:32:15 | 0:32:20 | |
An elephant in its trunk alone | 0:32:20 | 0:32:23 | |
has up to 40,000 different muscles | 0:32:23 | 0:32:27 | |
and it has to use each of those muscles in different | 0:32:27 | 0:32:30 | |
combinations for different tasks. | 0:32:30 | 0:32:32 | |
Makes learning to ride a bike look really rather easy. | 0:32:32 | 0:32:37 | |
Getting the muscle combination right is all about trial and error. | 0:32:37 | 0:32:43 | |
It takes practice to master the movement of the most complex | 0:32:44 | 0:32:50 | |
and useful nose on the planet. | 0:32:50 | 0:32:53 | |
By the time an elephant is just one year old, | 0:32:56 | 0:32:59 | |
it can use that trunk for drinking, lifting, pulling, twisting, | 0:32:59 | 0:33:04 | |
even the most precise of movements | 0:33:04 | 0:33:07 | |
so they're really not such slow learners after all. | 0:33:07 | 0:33:11 | |
The way an animal moves can be just as appealing as how it looks. | 0:33:15 | 0:33:21 | |
Our emotional response is amplified when it's a young animal | 0:33:23 | 0:33:28 | |
learning how to get this movement just right. | 0:33:28 | 0:33:32 | |
Clumsiness in babies of all species is another major trigger | 0:33:39 | 0:33:44 | |
of the cute response. | 0:33:44 | 0:33:46 | |
Which probably explains why we love penguins. | 0:33:55 | 0:34:00 | |
That wonderful waddle from side to side | 0:34:04 | 0:34:08 | |
makes a penguin look just like a toddling baby. | 0:34:08 | 0:34:12 | |
But unlike our early teetering, | 0:34:14 | 0:34:17 | |
a waddle isn't part of a learning process. | 0:34:17 | 0:34:20 | |
It isn't refined or finessed. | 0:34:23 | 0:34:25 | |
A chick remains Chaplin-esque | 0:34:29 | 0:34:32 | |
through to adulthood. | 0:34:32 | 0:34:34 | |
Most animals have evolved to get themselves | 0:34:39 | 0:34:42 | |
from A to B efficiently. | 0:34:42 | 0:34:44 | |
So, why do penguins resort to waddling? | 0:34:45 | 0:34:49 | |
Well, although they breed and bring up their chicks on land, | 0:34:50 | 0:34:54 | |
most of their lives are spent in the ocean. | 0:34:54 | 0:34:58 | |
Underwater, they are transformed. | 0:35:05 | 0:35:09 | |
Penguins are highly adapted to live in the water, | 0:35:12 | 0:35:15 | |
they have that torpedo-like shape that means | 0:35:15 | 0:35:18 | |
they can swim very fast and they actually really fly underwater. | 0:35:18 | 0:35:21 | |
Their chest muscles are very large to drive their wings. | 0:35:21 | 0:35:26 | |
Their legs are very short, sort of tucked away at the back. | 0:35:26 | 0:35:30 | |
They act as rudders. | 0:35:30 | 0:35:32 | |
They can reach bursts of 25mph | 0:35:34 | 0:35:38 | |
which, compared to, say an Olympic swimmer, | 0:35:38 | 0:35:40 | |
is about six maximum speed, so they're very agile. | 0:35:40 | 0:35:45 | |
Emperor penguins, | 0:35:47 | 0:35:48 | |
the largest penguins, can hold their breath for over half an hour | 0:35:48 | 0:35:52 | |
and can reach depths of half a kilometre, | 0:35:52 | 0:35:56 | |
so they're very accomplished divers and very accomplished swimmers. | 0:35:56 | 0:36:00 | |
Underwater, a penguin is a torpedo in a tuxedo. | 0:36:02 | 0:36:06 | |
But on land, these fantastic adaptations prove, well, | 0:36:09 | 0:36:13 | |
to be a bit of a problem. | 0:36:13 | 0:36:17 | |
Short legs and big feet don't help cover distance. | 0:36:20 | 0:36:25 | |
PENGUINS SCREECH | 0:36:26 | 0:36:29 | |
The waddle was written off as an evolutionary handicap. | 0:36:29 | 0:36:35 | |
Scientists thought that waddling was very inefficient originally | 0:36:35 | 0:36:38 | |
because if you look at the energy consumption of penguins | 0:36:38 | 0:36:41 | |
and their walking, it's very high. | 0:36:41 | 0:36:44 | |
It was thought that the side-to-side motion was wasted energy. | 0:36:44 | 0:36:48 | |
But then a study of penguin locomotion | 0:36:48 | 0:36:52 | |
made a surprising discovery. | 0:36:52 | 0:36:54 | |
By swinging their body weight over one foot, | 0:36:59 | 0:37:03 | |
then using momentum to pivot onto the next, | 0:37:03 | 0:37:06 | |
penguins barely use their leg muscles at all. | 0:37:06 | 0:37:10 | |
So, it looks very inefficient but it can actually | 0:37:13 | 0:37:16 | |
recover 80% of the energy it's using for each stride for the next one. | 0:37:16 | 0:37:21 | |
So, it turns out that it's the best way to get about. | 0:37:21 | 0:37:25 | |
If you aren't built to walk, then waddling isn't a bad solution. | 0:37:28 | 0:37:34 | |
Imagine this is a penguin waddling. | 0:37:36 | 0:37:40 | |
METRONOME CLICKS | 0:37:40 | 0:37:41 | |
Rather than moving forward and using energy to pick up legs and feet, | 0:37:41 | 0:37:46 | |
the penguin swings from side to side. | 0:37:46 | 0:37:50 | |
Each swing stores up energy for the next swing. | 0:37:50 | 0:37:54 | |
That way, a penguin can use momentum and gain ground and waddling | 0:37:54 | 0:38:00 | |
might not be the most elegant way of moving around but a penguin's | 0:38:00 | 0:38:05 | |
ability to waddle allows it to survive under the water and on land. | 0:38:05 | 0:38:10 | |
And penguins aren't the only animal | 0:38:13 | 0:38:16 | |
whose iconic movement hides a surprising secret. | 0:38:16 | 0:38:20 | |
Although summer days in the outback can soar past 50 degrees... | 0:38:33 | 0:38:38 | |
..you'll never see a hot-and-bothered-looking koala. | 0:38:40 | 0:38:45 | |
Scientists have recently discovered that koalas' | 0:38:46 | 0:38:50 | |
iconic tree-cuddling holds the key to survival in the baking heat. | 0:38:50 | 0:38:56 | |
While the air temperature sizzles, | 0:38:58 | 0:39:00 | |
the bark of a tree can be up to nine degrees cooler. | 0:39:00 | 0:39:05 | |
By pressing the thinner fur of their bellies against the bark, | 0:39:07 | 0:39:11 | |
a koala can lose some excess heat | 0:39:11 | 0:39:14 | |
and keep its core temperature in check. | 0:39:14 | 0:39:18 | |
We find weird and wonderful movements | 0:39:29 | 0:39:32 | |
incredibly appealing. | 0:39:32 | 0:39:35 | |
But for the animals, | 0:39:35 | 0:39:37 | |
they're perfect adaptations | 0:39:37 | 0:39:40 | |
to get them around a problem. | 0:39:40 | 0:39:42 | |
A dexterous trunk... | 0:39:45 | 0:39:48 | |
..a comic waddle... | 0:39:50 | 0:39:53 | |
or a cuddle is key to success. | 0:39:53 | 0:39:59 | |
But it's not just visual clues that trigger our cute response. | 0:40:02 | 0:40:08 | |
Sounds can be just as powerful. | 0:40:08 | 0:40:12 | |
This is Eli, he's a five-year-old chimpanzee | 0:40:14 | 0:40:18 | |
and it is incredibly easy to see why our species | 0:40:18 | 0:40:22 | |
has such a strong affinity for his species. | 0:40:22 | 0:40:25 | |
I mean, look, we could be brothers. | 0:40:25 | 0:40:27 | |
HE IMPERSONATES CHIMPANZEE | 0:40:27 | 0:40:29 | |
Well, brothers from another mother. | 0:40:29 | 0:40:32 | |
The mannerisms and expressions of apes | 0:40:40 | 0:40:44 | |
make them a firm favourite. | 0:40:44 | 0:40:47 | |
We are so alike. | 0:40:52 | 0:40:54 | |
And there's one particular behaviour, | 0:40:56 | 0:40:59 | |
a sound that we share, | 0:40:59 | 0:41:01 | |
that's recently piqued expert interest. | 0:41:01 | 0:41:05 | |
A troop of chimpanzees is just like any human family. | 0:41:10 | 0:41:14 | |
They hang out, | 0:41:16 | 0:41:17 | |
play and they laugh. | 0:41:17 | 0:41:21 | |
HE IMPERSONATES CHIMPANZEE | 0:41:25 | 0:41:28 | |
Eli is still a child and like any child, | 0:41:28 | 0:41:33 | |
he shows his enjoyment and his personality through laughter. | 0:41:33 | 0:41:37 | |
Are you tickly? | 0:41:40 | 0:41:41 | |
Are you tickly? You are. | 0:41:41 | 0:41:43 | |
ELI LAUGHS | 0:41:43 | 0:41:45 | |
If you get the right spot, he really, really enjoys it. | 0:41:45 | 0:41:48 | |
Look at you, look at that face. | 0:41:48 | 0:41:50 | |
That's good. I've got you, see? | 0:41:50 | 0:41:55 | |
It's really infectious, you see Eli laughing | 0:41:56 | 0:41:59 | |
and it makes you want to laugh. | 0:41:59 | 0:42:01 | |
And recently, scientists started to take laughter seriously... | 0:42:01 | 0:42:08 | |
..wondering whether the similarity between the sounds we make | 0:42:12 | 0:42:16 | |
might tell us more about our own evolution. | 0:42:16 | 0:42:20 | |
We were interested | 0:42:20 | 0:42:22 | |
whether we share our emotional | 0:42:22 | 0:42:25 | |
behaviours with apes | 0:42:25 | 0:42:28 | |
and there were some very interesting cues that indicated that | 0:42:28 | 0:42:33 | |
laughter may have deep biological roots. | 0:42:33 | 0:42:36 | |
In the name of science, Marina started tickling. | 0:42:36 | 0:42:43 | |
She collected footage from chimps, | 0:42:43 | 0:42:45 | |
orang-utans... | 0:42:45 | 0:42:48 | |
and gorillas. | 0:42:48 | 0:42:50 | |
We recorded these sounds and used these sounds in order to | 0:42:53 | 0:42:58 | |
conduct a systematic acoustic analysis. | 0:42:58 | 0:43:01 | |
When Marina gathered all the giggles together, | 0:43:01 | 0:43:05 | |
a pattern began to emerge. | 0:43:05 | 0:43:09 | |
The apes furthest away from us on the evolutionary tree, | 0:43:11 | 0:43:14 | |
orang-utans and gorillas, | 0:43:14 | 0:43:15 | |
made a very simple sound when tickled. | 0:43:15 | 0:43:18 | |
But tickling our closer cousins, chimps, | 0:43:20 | 0:43:23 | |
produced a more complex laugh sound. | 0:43:23 | 0:43:27 | |
Due to this matching, we could conclude that these vocalisations | 0:43:28 | 0:43:32 | |
that we examined were laugh vocalisations and that apes produced | 0:43:32 | 0:43:36 | |
laughter and that laughter is at least 13 to 16 million years old. | 0:43:36 | 0:43:42 | |
Bonobos, who are the most similar to us genetically, | 0:43:45 | 0:43:49 | |
also had the most human-like laugh. | 0:43:49 | 0:43:53 | |
Marina's findings show that laughter has evolved with us. | 0:43:55 | 0:44:00 | |
HE IMPERSONATES CHIMPANZEE | 0:44:02 | 0:44:03 | |
You can see when Eli laughs, he laughs like this... | 0:44:03 | 0:44:06 | |
ho-ho-ha-ha... | 0:44:06 | 0:44:07 | |
so he's using his outward breath and his inward breath. | 0:44:07 | 0:44:10 | |
ELI LAUGHS | 0:44:12 | 0:44:15 | |
You see what's happening, | 0:44:15 | 0:44:16 | |
when I laugh it's on the outward breath - ha, ha, ha, ha. | 0:44:16 | 0:44:20 | |
And that's something that we do subconsciously, | 0:44:20 | 0:44:23 | |
but it's because we can control our breathing | 0:44:23 | 0:44:26 | |
and it's our human ability to control our breathing | 0:44:26 | 0:44:28 | |
that has led us to develop speech, | 0:44:28 | 0:44:31 | |
so isn't it fantastic to think | 0:44:31 | 0:44:33 | |
that we might have laughter to thank for that? | 0:44:33 | 0:44:35 | |
HE IMPERSONATES CHIMP | 0:44:35 | 0:44:36 | |
You agree, it is fantastic. | 0:44:36 | 0:44:39 | |
'We find a chimp's laughter so appealing because we recognise it. | 0:44:39 | 0:44:44 | |
'It's a sound we associate with pleasure.' | 0:44:44 | 0:44:48 | |
ELI LAUGHS | 0:44:48 | 0:44:50 | |
But sometimes more unexpected sounds grab our attention. | 0:44:52 | 0:44:57 | |
RAIN FROG SQUEAKS | 0:44:57 | 0:45:00 | |
Like this desert rain frog. | 0:45:00 | 0:45:03 | |
Squeaking viral sensation. | 0:45:03 | 0:45:05 | |
RAIN FROG SQUEAKS | 0:45:05 | 0:45:10 | |
11 million hits and counting. | 0:45:10 | 0:45:13 | |
It sounds like a dog toy, | 0:45:13 | 0:45:16 | |
but actually this... | 0:45:16 | 0:45:17 | |
RAIN FROG SQUEAKS | 0:45:17 | 0:45:18 | |
..is the sonorous war cry of a very angry frog. | 0:45:18 | 0:45:24 | |
RAIN FROG SQUEAKS | 0:45:24 | 0:45:27 | |
Ferocious. | 0:45:27 | 0:45:29 | |
And there's another animal who became an internet celebrity | 0:45:34 | 0:45:39 | |
by making an even more surprising sound. | 0:45:39 | 0:45:42 | |
HUMMINGBIRD SNORES | 0:45:43 | 0:45:45 | |
A scientist in Peru... | 0:45:45 | 0:45:47 | |
HUMMINGBIRD SNORES | 0:45:47 | 0:45:49 | |
..captured this | 0:45:49 | 0:45:50 | |
escaping from the tiny body of a sleeping hummingbird. | 0:45:50 | 0:45:55 | |
HUMMINGBIRD SNORES | 0:45:55 | 0:45:58 | |
A high-pitched... | 0:45:58 | 0:45:59 | |
HUMMINGBIRD SNORES | 0:45:59 | 0:46:01 | |
..but unmistakable snore. | 0:46:01 | 0:46:04 | |
Hummingbirds are loved for their beauty and speed | 0:46:06 | 0:46:10 | |
but this one was behaving a little bit like a human. | 0:46:10 | 0:46:15 | |
The perfect cute response trigger. | 0:46:15 | 0:46:20 | |
But was the online fame deserved? | 0:46:20 | 0:46:23 | |
Is this bird really snoring? | 0:46:23 | 0:46:26 | |
Even before the snore, hummingbirds fascinated scientists. | 0:46:34 | 0:46:39 | |
From the day I first laid eyes on them, | 0:46:42 | 0:46:46 | |
they appealed to me because they are just such unique creatures. | 0:46:46 | 0:46:50 | |
They are the only true species of bird | 0:46:52 | 0:46:55 | |
that actually can hover for sustained amounts of time. | 0:46:55 | 0:46:58 | |
The smaller species will flap their wings about 60 times a second. | 0:46:59 | 0:47:03 | |
Try to move your arm that fast, it's pretty difficult. | 0:47:03 | 0:47:06 | |
The smallest hummingbirds weigh as little as 2g, | 0:47:08 | 0:47:12 | |
which is less than a paper clip. | 0:47:12 | 0:47:13 | |
HUMMING | 0:47:13 | 0:47:17 | |
This rapid movement is a lot to ask for such a tiny body. | 0:47:17 | 0:47:22 | |
It uses up so much energy, | 0:47:22 | 0:47:25 | |
that a hummingbird needs to feed almost constantly. | 0:47:25 | 0:47:30 | |
A sugar-rich hit of nectar every 15 minutes. | 0:47:36 | 0:47:41 | |
During the day, regularly sipping nectar | 0:47:45 | 0:47:48 | |
gives a hummingbird enough energy to survive. | 0:47:48 | 0:47:52 | |
But they can't do this for a full 24 hours. | 0:47:56 | 0:48:00 | |
They need rest. | 0:48:00 | 0:48:02 | |
The sun's about to set and fairly soon, | 0:48:12 | 0:48:15 | |
I'm going to want to go to sleep. | 0:48:15 | 0:48:17 | |
That's not a problem because through today, I've taken on board | 0:48:17 | 0:48:20 | |
more than enough calories to see me through the night, | 0:48:20 | 0:48:23 | |
but a hummingbird has to feed every 30 minutes or so | 0:48:23 | 0:48:27 | |
even when it's not flying. | 0:48:27 | 0:48:29 | |
To sleep through the night without feeding | 0:48:29 | 0:48:32 | |
could be incredibly dangerous, | 0:48:32 | 0:48:34 | |
so, the hummingbird is left with one drastic option | 0:48:34 | 0:48:38 | |
and that is to shut down entirely. | 0:48:38 | 0:48:41 | |
Their heart rate drops from 1,000 beats a minute to just 50. | 0:48:44 | 0:48:50 | |
Their breathing becomes almost non-existent... | 0:48:51 | 0:48:56 | |
..using just enough energy to stay alive. | 0:48:58 | 0:49:01 | |
It's called torpor... | 0:49:02 | 0:49:05 | |
and scientists like Don are only now beginning to understand it. | 0:49:05 | 0:49:11 | |
Most of what we know about torpor's been learned in the laboratory. | 0:49:12 | 0:49:16 | |
We take a hummingbird | 0:49:16 | 0:49:18 | |
and we will put it in what we call a metabolism chamber. | 0:49:18 | 0:49:23 | |
We measure the oxygen content of the air. | 0:49:23 | 0:49:27 | |
If their oxygen consumption gets really, really low | 0:49:29 | 0:49:32 | |
so that it's even difficult to measure, | 0:49:32 | 0:49:35 | |
then we know that the bird is in torpor. | 0:49:35 | 0:49:38 | |
HUMMINGBIRD SNORES | 0:49:40 | 0:49:42 | |
The internet footage is actually from an experiment | 0:49:42 | 0:49:46 | |
very similar to Don's. | 0:49:46 | 0:49:48 | |
The hummingbird has spent the night in torpor to save energy. | 0:49:50 | 0:49:55 | |
But that doesn't explain the snoring. | 0:49:58 | 0:50:01 | |
Sleep and torpor are very different. | 0:50:03 | 0:50:05 | |
When we go to sleep, our lungs are still working, | 0:50:05 | 0:50:08 | |
our hearts are still beating away | 0:50:08 | 0:50:10 | |
and we can wake up really quite quickly, | 0:50:10 | 0:50:12 | |
but for a hummingbird to come round from torpor, | 0:50:12 | 0:50:14 | |
it has to kick-start its entire body, | 0:50:14 | 0:50:17 | |
it has to get its breathing and its heart rate back up to speed. | 0:50:17 | 0:50:20 | |
Which is exactly what this hummingbird's doing. | 0:50:21 | 0:50:25 | |
The sound is actually a by-product of them gasping for oxygen... | 0:50:26 | 0:50:30 | |
..much like air rushing across a vocal chord's would. | 0:50:32 | 0:50:35 | |
Coming to with a snore of sorts. | 0:50:36 | 0:50:40 | |
The very sweet side-effect of a fascinating survival strategy. | 0:50:41 | 0:50:47 | |
RAIN FROG SQUEAKS | 0:50:48 | 0:50:52 | |
We associate high-frequency sounds with surprise, comedy... | 0:50:52 | 0:50:58 | |
PENGUIN SCREECHES | 0:50:58 | 0:51:00 | |
..and coming from such unexpected animals, they're pretty funny. | 0:51:00 | 0:51:05 | |
PENGUIN SCREECHES | 0:51:05 | 0:51:07 | |
But lower frequencies are proven to be soothing, calming - | 0:51:13 | 0:51:20 | |
opposite but equally powerful effects. | 0:51:20 | 0:51:24 | |
CAT PURRS | 0:51:24 | 0:51:28 | |
And it's this soothing quality that has brought us closer | 0:51:28 | 0:51:33 | |
to one species than any other. | 0:51:33 | 0:51:36 | |
CAT PURRS | 0:51:36 | 0:51:37 | |
This is an animal that we have an especially close relationship with. | 0:51:39 | 0:51:45 | |
Cats have lived side by side with us, | 0:51:47 | 0:51:49 | |
sharing our homes for thousands of years. | 0:51:49 | 0:51:54 | |
There are an estimated 200 million pet cats worldwide | 0:51:54 | 0:52:01 | |
and over two million internet cat videos. | 0:52:01 | 0:52:05 | |
I think it's fair to say we're obsessed. | 0:52:05 | 0:52:09 | |
They tick all the boxes. | 0:52:10 | 0:52:13 | |
Big forward-facing eyes, | 0:52:13 | 0:52:16 | |
furry, | 0:52:16 | 0:52:18 | |
elegant movement... | 0:52:18 | 0:52:21 | |
but the greatest appeal lies in the noise they make. | 0:52:21 | 0:52:25 | |
CAT PURRS | 0:52:25 | 0:52:29 | |
I'm not much of a pet cat person. | 0:52:31 | 0:52:34 | |
Sahara here is much more my kind of feline. | 0:52:34 | 0:52:38 | |
She is an eight-year-old cheetah and she is absolutely beautiful, | 0:52:38 | 0:52:44 | |
but she's also a very powerful predator. | 0:52:44 | 0:52:49 | |
So, I wouldn't quite want her sitting up on my lap | 0:52:49 | 0:52:53 | |
but just like a domestic cat, she also purrs. | 0:52:53 | 0:52:59 | |
SAHARA PURRS | 0:52:59 | 0:53:01 | |
Purring is a way of communicating. | 0:53:01 | 0:53:04 | |
It's a way of a cheetah saying, "I'm OK, I'm relaxed." | 0:53:04 | 0:53:09 | |
And they do it when they're grooming | 0:53:12 | 0:53:14 | |
and they do it when they're with their cubs. | 0:53:14 | 0:53:17 | |
SAHARA PURRS | 0:53:20 | 0:53:22 | |
Many cat species purr, | 0:53:24 | 0:53:26 | |
cheetah to moggy. | 0:53:26 | 0:53:29 | |
It's made when the muscles in the throat contract and relax... | 0:53:31 | 0:53:36 | |
CATS PURR | 0:53:36 | 0:53:38 | |
..making air vibrate past the voice box. | 0:53:38 | 0:53:41 | |
A purring cat is a happy cat. | 0:53:44 | 0:53:48 | |
But they'll also purr when injured or unwell | 0:53:48 | 0:53:52 | |
and this is where it gets interesting, | 0:53:52 | 0:53:55 | |
because purring uses energy... | 0:53:55 | 0:53:59 | |
..and why would a poorly cat waste precious resources? | 0:54:00 | 0:54:05 | |
SAHARA PURRS | 0:54:05 | 0:54:07 | |
Her purr really is incredible. | 0:54:07 | 0:54:10 | |
You can't just hear it, you can actually feel it thrumming | 0:54:10 | 0:54:13 | |
and vibrating through her whole body | 0:54:13 | 0:54:17 | |
and new research has suggested that purring | 0:54:17 | 0:54:19 | |
might have some hidden health benefits. | 0:54:19 | 0:54:22 | |
The frequency of the purr is very similar to the sound waves | 0:54:24 | 0:54:29 | |
that doctors use to help repair muscle and bone, so, | 0:54:29 | 0:54:34 | |
while she's resting, she could very well be giving her body a once-over. | 0:54:34 | 0:54:39 | |
Restoration. | 0:54:40 | 0:54:42 | |
SAHARA PURRS | 0:54:42 | 0:54:45 | |
But, unfortunately for us, a purr is not all positive. | 0:54:49 | 0:54:56 | |
Cats were first domesticated over 9,000 years ago... | 0:54:56 | 0:55:01 | |
..which means they've had plenty of time to get to know us. | 0:55:02 | 0:55:07 | |
Perhaps too much time. | 0:55:07 | 0:55:11 | |
Recent research discovered a second type of purr that cats use, | 0:55:12 | 0:55:18 | |
not to heal, but to get their own way. | 0:55:18 | 0:55:23 | |
It's louder and more urgent | 0:55:27 | 0:55:31 | |
and the masterstroke is that extra-high pitch... | 0:55:31 | 0:55:36 | |
CAT PURRS WITH HIGH PITCH | 0:55:36 | 0:55:38 | |
..a peak of 600 Hz... | 0:55:38 | 0:55:42 | |
..which mimics the frequency of a human baby's wail. | 0:55:43 | 0:55:49 | |
CAT PURRS WITH HIGH PITCH | 0:55:49 | 0:55:52 | |
Cats have perfected a purr that we find impossible to ignore... | 0:55:53 | 0:56:00 | |
..using it when they want to be fed, or to get a stroke. | 0:56:02 | 0:56:07 | |
It's psychological manipulation. | 0:56:09 | 0:56:12 | |
We are powerless to the purr. | 0:56:14 | 0:56:18 | |
Cunning and incredibly clever. | 0:56:18 | 0:56:21 | |
SAHARA PURRS | 0:56:21 | 0:56:24 | |
Whether it's a soothing purr... | 0:56:26 | 0:56:30 | |
..a massive head... | 0:56:31 | 0:56:33 | |
HUMMINGBIRD SNORES | 0:56:33 | 0:56:35 | |
..or a sweet little snore... | 0:56:35 | 0:56:38 | |
..the reasons we love certain animals are as diverse and different | 0:56:40 | 0:56:47 | |
as the animals themselves. | 0:56:47 | 0:56:50 | |
Every comic movement, | 0:56:50 | 0:56:53 | |
oversized feature, | 0:56:53 | 0:56:55 | |
and wonderful sound | 0:56:55 | 0:56:59 | |
tells a story of evolution | 0:56:59 | 0:57:03 | |
and survival. | 0:57:03 | 0:57:08 | |
Extraordinary lives need extraordinary features. | 0:57:08 | 0:57:11 | |
It's what makes these animals successful. | 0:57:11 | 0:57:14 | |
But the way that we are drawn to them, | 0:57:14 | 0:57:17 | |
our cute response, really is just a bizarre accident of our biology. | 0:57:17 | 0:57:22 | |
The way they look, the way they sound, the way they behave, | 0:57:22 | 0:57:26 | |
their biology, that's what's really interesting. | 0:57:26 | 0:57:30 |