Your Inner Fish

Neil shubin: When I look at my fellow humans,

I see ghosts of animals past...

Glimpses of an epic story that's hidden inside us all.

My name's Neil shubin.

As a scientist, I look at human bodies

different from most people.

The way we grip with our hands,

we can thank our primate ancestors for that.

How we hear so many sounds...

That dates back to creatures the size of a shrew.

And the further back we go, the stranger it gets.

To reveal why we look the way we do,

we'll travel through the distant reaches

of our family tree...

And meet an unusual cast of characters...

The ancestors that shaped your body...

The family you never knew you had.

From the badlands of Ethiopia...

She's beautiful.

To the shores of Nova Scotia...

This is the spot.

We'll search for clues that lie buried in rock...

His eyes are like globes,

and he's like, "I found it, I found it!"

And search for answers written in our DNA.

Peter Holland: I think it gives us a glimpse

into the brain of our ancestors...

Neil: I mean, I find that mind-blowing.

The adventure begins with a search

for some of our most elusive relatives...

Fish that crawled onto land

hundreds of millions of years ago.

From our necks and lungs to our limbs and hands,

we owe a lot to these intrepid pioneers.

So if you really want to see why you're built the way you are...

It's time to meet your inner fish.

Announcer: Your inner fish is brought to you in part

by viewers like you.

Thank you.

Ted: Wow, look at that! Paradise!

Neil: Yeah!

Ted: That is perfect!

Neil: He's going right up the valley.

The Canadian arctic is one

of the most desolate regions of the planet...

But there's nowhere else I'd rather spend the summer.

What draws me here is treasure...

My kind of treasure:

Fossils hidden inside ancient rocks.

In particular, the fossils of long dead fish.

But not just any old fish.

I'm hunting for fish

that carry the story of our own bodies inside of them.

How I got here and what I found

could change the way you think about yourself and your body.

This is a story that ends on top of the world

with the most important discovery of my life.

But it begins in the city of Chicago...

With a room full of human cadavers.

It was more than a decade ago,

and I'd just moved to the university of Chicago

as chairman of the anatomy department.

And I remember, you know,

hanging around with the students around the tables here,

just getting to know them and letting them get to know me.

They're launching their careers as future physicians,

and there's some nerves and skittishness

those first few days,

and they almost invariably ask,

"Dr. Shubin, what kind of doctor are you?

You know, are you a surgeon?

Are you a cardiologist?"

And I'd say, "well, no, I'm a fish paleontologist!"

And I'd get this look like "what? I want my money back."

But it soon became clear that being a paleontologist,

and not just any paleontologist...

A fish paleontologist...

Is a very powerful way to teach human anatomy.

Because often some of the best road maps to our own bodies

are seen in other creatures.

Now, you might not think your body

has much in common with a fish,

but I see a family resemblance.

On the surface you're not very fish-like, I'll admit.

But you are related to them.

And the clues to that connection are etched in ancient stone.

Fossils unearthed around the world

reveal that fish are the first creatures with bony skeletons.

They have backbones and skulls, just like you and me.

This shared anatomy connects us to fish...

And to a long line of other animals.

To see what I mean, imagine the complete history of life

on a giant family tree,

from the first microscopic organisms billions of years ago

to a all animals alive today.

Our history lies on one branch of this tree of life...

And can trace our ancestry back.

Around 400 million years ago

you'll find fish swimming in oceans and streams.

40 million years later

the first amphibians appear on land.

Then we see reptiles...

Followed by the first mammals around 200 million years ago.

And much later, we arrive at our special branch, primates.

This history tells us something remarkable:

Every reptile, bird and mammal alive today

is descended from ancient fish.

And that includes us!

So how does this legacy play out in our anatomy?

Each one of us walking around in this lab today

carries the history of life within us.

And the evidence is seen in every part of our bodies.

And not just in our bones.

Even the complex tangle of nerves inside the human head

makes much more sense when you realize

it's the same basic wiring found in fish.

But there's one defining piece of human anatomy

that seems remote from the world of fish...

And I vividly remember when it first captured my imagination.

When I walked into the anatomy lab

for the first time,

I was sort of scared about what I was going to see,

what I was going to feel,

but the reality is after the first few weeks,

that fear turns into a sort of a cocky self-confidence.

And these things, you know, when you dissect them,

it doesn't look very human,

it kind of looks like a wax model in a lot of ways,

but then you hit the hand.

And for me, as I unwrapped the gauze

and revealed the palm, the fingers, the fingernails,

something else hit me entirely.

And that was a deep sense of connection,

a connection to another human body lying on that slab...

This was not a wax model that I was dissecting,

this formerly was a person

who lived a life just like I am living now.

When I see the anatomy within the human hand,

I'm in awe of the intricate connections

between bone, tendon and muscle.

Really it's through the action

of these muscles through the tendons

that the hand does its, you know,

does its magic, if you will.

So that when the muscles fire, it pulls on these tendons,

and watch... The fingers flex.

Now, the fine muscles of our hand...

These little tiny muscles that lie along the tendons.

These are the muscles

that control the fine motion of our fingers.

These are the ones

that are quintessentially primate and human.

So where did this marvel of evolution come from?

It clearly has deep roots in the past...

And you can see evidence of that

in the bones of modern creatures.

More than 150 years ago,

scientists were finding connections

between the hands and limbs of four-legged animals.

Sir Richard Owen was an anatomist

in the 19th century.

He was fortunate to be an anatomist

in an age of discovery.

And so people were coming back to London

with new and oddball creatures for him to analyze,

and in analyzing all the different creatures

he found common patterns.

Although the overall shape and structure of each limb

was very different,

he started to see that there was an underlying theme.

It was as if the same set of bones

was being squashed or extended to perform different functions.

Here's a dog.

Dogs, you know, run and jump.

What do you have?

One bone, two bones, little bones,

and then the digits,

the equivalents of the fingers or toes.

And, of course, here's a bird.

Its limb has been modified into a wing,

and it has one bone, two bones,

lots of bones, and the digits.

The amazing fact is, in each of these creatures,

the skeletal architecture is largely the same as ours,

and what was utterly surprising

is that the skeleton of every animal walking the earth today

has this fundamental pattern of one bone, two bones,

little bones, fingers.

Owen didn't know why creatures had that pattern.

It was a mystery to him.

It really took a new insight, an insight from Charles Darwin,

which basically said the reason

why animals have this common pattern

is because at some time in the distant past

they all shared a common ancestor

that had a version of this pattern, too.

According to Darwin, we should be able to trace

the evolution of our limbs and hands

by going back in time down our family tree.

Starting with our primate ancestors,