[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]