Explained (2018–…): Season 2, Episode 3 - Animal Intelligence - full transcript

[man] Who's that in the mirror?

[Hilary Swank] This is known as
the mirror self-recognition test.

Some versions use a red mark,

and you pass if you recognize
that it's on your own face.

Children begin to pass
at around 18 months old,

which signals a major milestone
in their development.

Hey.

The mirror studies are so intriguing,

because at a very intuitive level,
we relate to the mirror.

Looking in a mirror, recognizing yourself
has something to do with self-awareness.

Humans aren't the only animals
that can recognize themselves.



Chimps were the first
to pass the mirror test.

Then others followed.

Dolphins, elephants...

even magpies.

And then recently,
the fish study came along.

I'm not a hundred percent on board
with the fish.

That fish passing was... controversial.

And the test has other surprising results.

Some monkeys don't pass,

even though they're widely seen
as intelligent animals.

If you're a dog owner,

you may have noticed
how your pet reacts to its reflection.

[barks]

Research on animal intelligence
over the last few decades



has sometimes been confounding,

but it's also given us
profound new insights

about where we fit into the world.

To anchor our understanding
of the human mind

more in where we come from, our ancestry,

uh, we need to know more about animals.

So how do other animals think?

And how does studying
the minds of animals

reveal what it is... to be human?

[man] Pretty clever bird, the parrot.
He can actually pronounce words.

Of course he has no idea
what the words mean.

- [Ed] I'm a horse, not a guinea pig.
- [laughter]

[man] Almost everybody
likes to watch animals,

whose instincts and intelligence
are sometimes remarkable.

[second man] The lifetime of all mankind
is but a brief moment

in the long history of this Earth of ours.

[third man] Not only can we control
many important variables,

but our subjects are available
when we need them.

♪ Hey, hey ♪

♪ Hey ♪

I think about
what's going on in her little head.

She's always looking around.
The wheels are always turning.

He's very smart.

He's already learned to say
probably about a dozen words or phrases.

He has a lot of opinions,
and he wants what he wants.

[man] Elliot's ego
is very easy to damage.

Whenever Elliot meets other rabbits,
we're always like,

"Oh, my God, he thinks
he's so much better than them."

He can be... I hate
that I'm gonna say this. He can be snappy.

You know, so many of us who have dogs
or cats or pets have wondered like,

"What are they thinking? Do they love me?
Like, do they understand this thing?"

It's such a human thing to do...

To wonder what's going on
inside another animal's head.

And we can't just ask them.

Animals clearly have ways
of communicating with each other.

Bees do it by dancing.

- Whales sing.
- [vocalizes]

- And chimpanzees gesture and scream.
- [screaming]

But humans have tens of thousands of words
at our disposal,

which, strung together, can communicate
an infinite number of ideas.

So seeing if animals

could communicate with us
in human language

was one of the first efforts
in animal-intelligence research.

And this was one of the first experiments

with a chimp named Viki in the late 1940s.

Now who am I?

Papa? Papa?

You can see it's not going so well.

It turned out chimp vocal cords
aren't built for speaking.

But then, in 1966,
a psychologist couple had another idea.

They brought home
a wild-born baby chimp name Washoe,

raised her like a human child,

and tried to teach her
American Sign Language.

Washoe ultimately learned about 150 signs,
like for these words...

[man] Toothbrush. Hug.

Open. Out.

The linguists had defined language
as symbolic communication.

Then Washoe came along,
and she was doing symbolic communication.

She was using hand signals
to refer to certain things.

Other high-profile
ape language studies followed

which seemed to show that the human mind
and our ability to communicate

wasn't so unique after all.

So the question was,
"Were these apes actually using language?"

This was a radical question.

Up until the late 19th century,
the assumption in most Western cultures

was that human minds
had nothing to do with animals.

That wasn't the case
in some Eastern religions like Buddhism.

That view of the universe
looked like this.

Humans and animals
shared the same essential nature

and were linked through rebirth.

But the Christian worldview
looked more like this.

Humans were superior
because they had souls,

and animals were ranked below them.

[Frans] You have mammals, then you go down
to the worms and the molluscs and so on.

Of course, humans were closest to God,

'cause the angels and God,
they were just-just above us.

[Swank] But Charles Darwin
changed all that

with this first sketch of a tree of life
in his notebook.

It might look small,

but this blew up that worldview
with the Theory of Evolution.

One of the things that Darwin did so well
in the Origin of Species

was to make vivid an alternative picture,

a picture in which
it's a tree, not a scale.

Where all animals
evolved from earlier life forms

and all life is related,
even if distantly,

Homo sapiens are right here. That's us.

Darwin also said that intelligence
must be on this tree, writing,

"The difference in mind
between man and the higher animals,

great as it is, certainly is one of degree
and not of kind."

But the mind is a hard thing
to study scientifically.

So for much of the 20th century,

mainstream psychology
measured behavior instead.

This school of thought
was called behaviorism.

Behaviorism became a sort of religion.

At first, I think their goals
were perfectly fine.

They said, "Let's move away from
internal states

like feelings and thoughts
and stuff like that

and just look at behavior."

But then behaviorism went further,

arguing that the mind
didn't really matter at all.

Any sign of intelligence

was just learned through
a system of rewards and punishments.

And that's one interpretation
of how apes learned language.

The psychologist B.F. Skinner
was the high priest of behaviorism.

[man] His work has been
both applauded and attacked,

because it details methods

to shape and control
the behavior of others.

[Swank] Skinner thought animals
were stimulus-response machines

and that you could teach them
almost anything

with the right rewards and punishments,
like teaching pigeons to read.

[man] He's learned
his different response to each sign

by being rewarded with food.

[Swank] Or to play ping-pong.

Or to fly a World War II missile,

which actually worked, but was never used.

Skinner thought humans
learned this way, too,

even if we were more advanced.

In a 1977 interview,

he argued that both human
and animal intelligence

was just conditioning.

Of course, human behavior
is extraordinarily different,

much more complex than animal behavior,

but the fundamental principles
are probably there.

[explosion]

But the linguist, Noam Chomsky,
disagreed with Skinner.

In an interview that same year,

Chomsky argued that humans
don't need to be conditioned

to acquire language.

We're built for it,
and it's clear from a young age.

Most parents

don't give any systematic instruction
of any kind to their children,

yet the children nevertheless learn.

In a certain sense, we might go on to say
language isn't even learned.

And he thought animals
were built for other things.

When asked whether apes like Washoe
could learn language, he responded,

"Humans can fly about 30 feet.
That's what they do in the Olympics.

Is that flying?
The question is totally meaningless."

After Washoe, researchers
taught sign language to another chimp,

Nim Chimpsky...

and reviewed the footage
of previous ape language studies,

and concluded that chimps
could imitate isolated words,

but couldn't speak in
spontaneous sentences or with grammar

the way humans do.

In the end, Nim Chimpsky's
longest sentence was these 16 words...

"Give orange me give eat orange

me eat orange

give me eat orange give me you."

Behaviorism fell out of favor.

Even though we now don't believe so much
anymore that they have language,

still, they opened up
that whole field of animal cognition

by showing that apes could do
much more than we thought.

Today, thanks to Darwin,

scientists agree that human intelligence
evolved from earlier primates

with the first big split
around seven million years ago

and another around 200,000 years ago.

That's when Homo sapiens appeared.

Then, in an evolutionary blink of an eye,
humans developed bigger brains,

complex languages, cultures,
technologies and civilizations

and spread out around the globe.

One theory about why
the human brain is exceptional

is that it just has more neurons.

The human brain
has roughly 100 billion of them.

That's over three times more
than a chimpanzee

and over a thousand times more
than a mouse.

But recently, a study found that elephants
have close to 260 billion neurons,

almost three times more than us.

Scientists have tried to figure out if
the kind of neurons we have are special.

They don't look special.

This is so true

that if you just look at a slide
of a human brain or a mouse brain,

and you showed a neuron from that slide
to a neuroscientist,

they'd be really hard-pressed to tell you

whether that came from a human brain
or from a mouse brain.

But not all neurons
have the same function.

Human brains
seem to have particular neurons

that activate
when we learn from others' behavior.

They're called mirror neurons.

But scientists have found similar neurons
in the brains of other primates.

And a study discovered them
in swamp sparrows, too.

[chirping]

They activated when the birds
mimicked the songs of other birds.

And so we haven't found
the special human neuron yet.

And there's a hundred billion neurons,
so there's still a lot to-to search.

Humans rank the highest

on the standard calculation
of brain-to-body ratio.

Other animals we perceive as intelligent
rank highly, too.

And bigger-brained animals
also tend to have longer lives.

Often when we're thinking about
intelligence in other animals,

we tend to focus on
the cognitive capacities

that we're super proud of in humans.

Like being socially smart,

because we develop the ability to live in
complicated social structures.

But chimps do too on a smaller scale

which requires the intelligence

to make careful judgments
about the feelings of others.

[Frans] Can I predict the behavior
of somebody else?

Can I challenge this individual?
Will I have backing if I do that?

How do I reconcile
and with whom do I reconcile after fights?

They have to make
complex decisions very often.

[Swank] Researchers think chimps
experience empathy

because they have yawn contagion.

A 2009 study

discovered that chimps will yawn
when shown a cartoon chimp yawning.

We used to believe we were unique
in how we use tools to solve problems.

We encounter problems
that we didn't know would be there, right?

Because the universe
is a little random, it's hard to predict,

and I think
one definition of intelligence

is can that animal solve that problem
that it encounters

to achieve whatever goal, uh, it wants.

But in the 1960s,

Jane Goodall discovered
widespread tool use among chimpanzees,

and then researchers discovered
something surprising.

Birds could do this, too.

[Frans] For example, New Caledonian crows
are very good tool users.

We know that now. They even make tools.
They modify them.

They can all do sequences of tools.

[Swank] While other animals

may solve problems
as they come across them,

humans thought we were at least special

in that we learn from our memories
and can plan for future problems.

We used to think of animals,
they're captive of the present.

We humans are different

because we tend to think
back in time to specific events.

We can think forward,
we can make plans for tomorrow

or even much further away,
and that makes us different.

But research on the Clark's Nutcracker,
another member of the crow family,

estimates they can hide
up to 30,000 seeds in the fall

in 6,000 different locations,

and then find them again
months later in the spring.

And I don't even know where
my car is being parked,

so I think it's pretty impressive
what they do.

But humans don't just
plan for their own future.

We plan for the future of our species.

We build schools, libraries, and museums.

We have culture.

[Bobby] Culture is this idea
of shared responsibility for our children.

And I think that model can be found

in rudimentary versions

of animals taking care of their children.

[Swank] In Côte d'Ivoire,

a study of three genetically related
groups of chimpanzees

found that each group
used different types of tools

to crack open the same African walnuts,

evidence that each group
taught their offspring differently.

And whales have culture, too.

[whale vocalizes]

This is a hit humpback whale song.

In 2009, only this group of whales
was singing it.

Then in 2010,

they encountered other whale groups
at a communal feeding spot,

and one of those other groups

abandoned their own song
and returned home singing this new tune.

They call this a cultural revolution.

Discoveries like this

disrupted our understanding
of how intelligence evolved.

Birds and whales

aren't as closely related to humans
as other primates.

Whales and humans, both mammals,

share an ancestor
around a hundred million years ago,

and our last common ancestor
with the crow family?

300 million years ago
before the dinosaurs.

We're kind of converging on
the same abilities,

not because we're closely related,

but because we've had
similar problems we've faced,

and we've come up with
the same cognitive structures.

This happened with physical traits
all over the animal world.

Unrelated species independently developed
similar traits to fit their needs,

like wings, dorsal fins, and venom.

And this happened to the mind, too.

Which is why animals
all over the evolutionary tree

may have a sense of self-awareness.

Except it's hard to tell with the fish.

One reason it might have tried
to scrape off the red mark

is because it could feel it

when researchers
pricked its scale with ink,

not because it recognized itself.

And the mirror test has other limitations.

Part of the problem, uh, is that
what the test that I gave you

is a very visual test,

and it might be that many animals
don't use vision

the way we use vision to recognize
a sentient other human beings.

Which highlights a fundamental flaw
in how we've studied the minds of animals.

In a way, many of our tests
have been like a mirror,

looking for human qualities,
using human measures

based on a human perception of the world.

This is what dogs' vision looks like
compared to humans'.

Dogs are red-green color-blind,

and their vision is between

four and eight times
less precise than humans'.

But they navigate their world
with their sense of smell,

which is 10,000 times stronger
than humans'.

So a researcher designed a test
with canisters of urine

to see if dogs
could recognize their own scent

from one mixed with other scents.

They lingered on the mixed scents
longer than their own,

indicating that dogs may be self-aware,

but mainly through smell instead of sight.

That may also explain why in 2011,

researchers found that elephants,
a smart animal by many standards,

failed a simple tool test

to use sticks to get food
just out of reach.

In order to understand the elephant,
we need to understand, for example,

the elephant has
a hundred times better smell than the dog.

But then the researchers
modified the test.

Instead of leaving out sticks,
they left out a box and tire

to see if the elephants
would stand on them to reach the food.

And the elephants passed.

And the reason is, we think,

because for an elephant
to pick up a stick...

it shuts off its smelling organ.

And so you need to understand
the elephant

and understand a trunk
is not the same as a hand.

It has very different functions.

Every animal has its own way
of looking at the world,

its own perceptual capacities.

Some animals hear things and see things
that we don't notice.

Take bats, for example,
a species that evolved the ability

to sense its surroundings
through echolocation.

This means they navigate
by making high-pitched sounds,

mostly imperceptible to human ears,
that bounce off nearby objects.

And salmon can use
the Earth's magnetic field like a compass

to navigate across
thousands of miles of open ocean

back to their spawning grounds.

The fact that we can't do these things

might make us seem pretty dumb
to a bat or a salmon.

We're just missing a lot of the stuff
that animals do

that's incredibly smart
and incredibly clever,

because we're using human intelligence
as the standard.

And the more we expand
our idea of intelligence

to include more animals,

the more we protect them.

The Spanish parliament passed a resolution
to grant rights to great apes

to protect them from captivity
or experimentation.

A similar case is being made in the U.S.

for the legal rights of the first elephant

that passed
the mirror self-recognition test.

And the Indian government
banned dolphin shows

because of the mounting evidence that
dolphins are a highly intelligent species.

We need to anchor our own existence,
so to speak, in nature.

We have a tendency to set ourselves apart.
We are separate.

We are not.
We are completely intertwined with it.

So we cannot handle nature any way we want
because we have to be careful.

Up until recently,

most research has focused on animals
that remind us of ourselves.

And we're just starting
to look beyond them.

[Bobby] Any of those ways
you think about the octopus,

it's probably as alien to the human

as any other animal on the planet.

[Swank] Octopuses or octopi...
Both are correct...

Are part of the cephalopod group
and show typical signs of intelligence.

Like humans and other primates and birds,

they use tools like this coconut shell
for protection,

and even carry tools with them
for future use,

meaning they are planners
like the Clark's Nutcracker.

They recognize individual people,

and they take an interest in new things,
like this camera.

If you bring an unfamiliar object
to most wild animals,

they're either scared of it
or they want nothing to do with it,

whereas an octopus
often regards a piece of plastic,

a brightly colored object of some sort,
as very interesting.

Octopuses and their cephalopod relatives,
cuttlefish,

can also totally transform
the color of their skin

in milliseconds,

something scientists

traditionally haven't considered
a sign of intelligence.

Perhaps because humans can't do it.

That's when you know
they're gonna take over the world.

They have eight arms and can do this.

It's obviously something terrible
between us and octopus

is gonna have to happen at some point.

[chuckles]

But octopuses

defy the classic correlations
with intelligence.

They live short lives, roughly two years,

and they tend to live alone,
not in social groups.

And it's hard to even plot
their brain-to-body ratios

because their brain and body
are hard to distinguish.

Of their roughly 500 million neurons,

2/3 are spread throughout their tentacles.

That could be because they are
further from humans than other primates,

other mammals,
and even birds on the evolutionary tree.

Our closest ancestor wasn't smart at all.

It was something like a worm
living 700 million years ago.

[Peter] For most of the time
animals have been evolving,

we've been on a separate path from them,
been on an independent track.

[Swank] But many scientists
believe octopuses

still found their way to an intelligence
we can recognize,

which means the possibility
of thinking-and-feeling animals

is everywhere
among the millions of species

sharing the world with us.

We'd like to understand
what kind of place the universe is.

One very important aspect
of that question

is which parts of the universe
have experiences

and have thoughts
and-and have minds?

I mean, is it just us? Is it everything?

Is it just some animals?

There's just a kind of importance
inherently to a question of that sort

if we want to understand
what kind of world we live in.

[closing music playing]