We fight for our country.

We cheer for it.

We draw our values from it.

It's a big way many of us describe who we are,

but it didn't used to be.

Up until really recently, our identities came from stuff

immediately around us —

clans, religion, family.

If you think about it, nationality

is weird, the idea that you identify

with millions of strangers just based on borders.

That's because national identity is made up.

“U.S.A.!

U.S.A.!”

“And then [INAUDIBLE] scores!”

National identity is the myth that built the modern world,

but it also primes us for dictatorship, racism, genocide.

And today, we're fighting over whether to keep

that kind of national identity.

To understand why, you have to see how new this idea is.

So you think you know what France is.

It's a place united by the French language

and the French ethnicity, right?

But as of the French Revolution, half of the people

there could not speak French.

Only one in eight spoke it well.

These are the languages that people spoke,

just a patchwork that didn't line up with borders.

We know from modern genetics that ethnicity didn't line up

with borders, either.

National identity became the idea

that language, race, and borders should add up to a country.

Nations can't admit they're made up,

so they invent a national mythology

that says they've been like this forever.

The modern era brought four big changes

that led to national identity.

People moved in big numbers from the country to the city,

and they needed a common language.

New technology, like newspapers and trains,

made countries feel smaller and more interconnected.

War was changing into this vast all-consuming thing.

Countries needed people that cared

so much about their nation,

they'd fight for it in huge numbers.

Governments were challenging religion for power.

Here's Napoleon taking his crown from the pope

to crown himself emperor.

It was a big deal.

These four things sparked an era of revolutions in democracy,

but they also unleashed ideas of nationalism, militarism,

and leader worship.

People came to see their countries

as extensions of themselves.

This new identity meant that a nation got its authority,

not from the government, or the King, or God,

but from the people.

This changed the world, but it also changed how we think.

National identity changes our reality.

We experience whatever happens to our nation

as if it happened to us.

“Rocky IV” can tell us a lot about what national identity

does to our brains.

“The Russian towers above the American.”

A 1994 study tested the attitudes of Americans

watching the movie.

It includes an amazing footnote.

All 216 participants were women because, quote,

“There were no males who had not seen 'Rocky IV.'”

Anyway —

When Rocky beat his Russian opponent,

participants who strongly identified as American

felt a boost in self-esteem.

When they were shown re-edited footage

to make it look like Rocky lost, they felt a drop in self-esteem

and they became likelier to hold negative views about Russians.

But when they said something bad about Russians,

their self-esteem recovered.

When we feel threatened, it makes

us want to humiliate and dominate the outsider.

That dynamic doesn't just apply to individuals.

It can apply to whole societies.

This can drive war, itself.

One study found that any country whose team

plays in the World Cup becomes likelier

to launch attacks abroad.

That hostility also plays out against minorities and migrants

who don't fit the national myth.

It only took a century for these problems of modern nationalism

to culminate into World War II, something so terrible,

it convinced the world to try a new kind of national identity.

“Great American melting pot.”

This model of identity is based on an idea from the United

States.

Anyone can be American if you share values

like freedom and hard work.

“May I please remind you that it does not say

RSVP on the Statue of Liberty.”

It's a stirring idea, but it never completely worked.

“Your race is your nation.”

“If you don't speak English and don't contribute, get out!”

The belief that being American is really

about race, religion, and language

also runs throughout history.

So what makes a country?

Which identity should matter?

That fight defines so much of the world right now.

And it's intensified.

You see it in the backlash to the European Union.

“We've got our country back.”

You see it in how Donald Trump began his campaign.

“We either have a country or we don't,

and it's that simple.”

The national myth is powerful.

We fight for a common past and a common future.

It isn't real, but that doesn't matter.

We've been taught for so long that this is who we are.

Building a world based on shared values

really means creating a new myth.

But that only works if it feels as powerful as the last one.