The Cognitive Tradeoff Hypothesis


[clangs] This is Inuyama, Japan, a historic city home to Japan’s oldest
original wooden castle. It is also home
to Kyoto University’s Primate Research Institute.Here, a group of chimpanzees
have been trained
to play a game that exposes
something shocking
about their memories.This is going
to blow your mind.
Here is how it works.Take a look at these numbers.1, 2, 3.Remember where they are,because they’re about
to disappear.
Can you point to where
each number used to be
in numerical order?Probably. It’s pretty easy.1, 2, 3.But what if we
make it harder?
Get ready to point to where
each number was in order…
now.If you feel like you didn’t
have enough time
to memorize the screen,
that’s fine.
It’s nothing
to be ashamed of.
Or is it?Here is a chimpanzee
taking exactly that long
to memorize the same
arrangement.
Nailed it.Each of these puzzles
is completely new
to the chimpanzee,but just a glance
is all it needs
to completely capture
all the numbers.
How can a chimpanzee’s memorybe so much better
than ours?
Well, one theory
is that we humans
are worse at this task
because we can talk.
What makes humans different
from other animals? Well, one thing is language. We have the cognitive ability to communicate not just about
what’s happening now, but also about what did happen,
and what could happen. We can tell stories,
and it’s awesome. But if language is so good, why didn’t any other animal
develop it like we did?A good approach
to this question
is one that looks
at how we are different
from those who were almost us.Around 7 million years ago,there were no chimpanzees
and there were no humans.
But there were CHLCAs,an acronym which stands for“Chimpanzee-Human
Last Common Ancestor.”
Like us,
CHLCAs didn’t have
great natural offenses
or defenses,
protective shells or claws,
fangs or venom.
So living in the safety
of the trees was great.
Those who stayed became
the chimps we know today.
But for reasons we’re still
not quite sure of,
some of the CHLCAs decided
to venture down to the savanna.
Without appropriate
physical abilities,
things like cooperation,
imagining new strategies,
and the assigning of roles
were necessary for survival,
all of which are easier
if you have
a rich collection of symbolsthat can refer to things
across time:
language.Many different types
of creatures emerged
with varying adaptations.But today, only one member
of the family remains.
Us.Language as we know it may have
been one of the strategies that kept us alive
in the savanna. But where did it move in? The brains of those
who developed language and those who didn’t
aren’t totally different. A brand-new brain structure
didn’t just pop into existence. Instead, anatomy used
for other tasks must have been sacrificed. And as it turns out,
for beautiful reasons, detailed short-term memory may have been
a fair thing to lose in return for language. This trade-off
between memory and language is the Cognitive Tradeoff
Hypothesis.The Cognitive Tradeoff
Hypothesis
is the culmination
of decades of work
by one of the world’s leading
primatologists,
Professor Tetsuro Matsuzawaof Kyoto University’s
Primate Research Institute.
Founded in 1967,the institute was created
for scientific research
in association with the nearby
Japan Monkey Center.
The collaborative centers house
over 60 species
and nearly 1,000 primates who
live and play in open spaces.
Look at monkeys. [monkeys chitter] Is there a baby
on that one? -[Michael] Six months?
-[Tetsuro] Yes. [gibbers] That’s where they live. [Michael]
Can you do it? [grunts]Dr. Matsuzawa has spent
over 40 years
researching
non-human primates.
He splits his time
between fieldwork
in the West African country
of Guinea,
and here in Japan,where he and his colleagues
have developed
a chimpanzee habitatdesigned to mimic life
in the wild.
This habitat is home to Skylab,
a working laboratory
set high atop the chimpanzee”
climbing structure.
In this open air lab,chimpanzees are free
to come and go as they please.
And this is how you move?If they decide to stay,they participate
in cognitively enriching tasks
designed to mimic
foraging behavior.
When the chimpanzees are
interested in participating,
they enter one of Skylab’sspecially designed
computer booths,
where a camera uses
facial recognition software
to recognize them
and select a test
based that particular chimp’s
current familiarity
with the task.Each trial takes about as longas it would for a chimp
to forage a single bite.
And each morsel
of food they get
is accounted for
in their diet.
Do the doors open
when they approach? No human even needs to be…?So, what is for us
a great way to collect data,
is for them an experiencesimilar in many waysto what they would be doing
in the wild.
Impressive.Dr. Matsuzawa has been running
memory tests like these
on chimpanzees since 1978.His research has shown
the phenomenal
and nearly photographic
short-term memory
of these primates.Two of the most famous chimps
at the PRI are Ai,
named after the Japanese word
for “love,”
and her son Ayumu,
whose name means “walk.”
What can we learn
about ourselves
by studying chimpanzees
like them?
Well, I want to find out.If we and chimpanzees
come from a common ancestor, what can explain the split
where the chimpanzees don’t seem to need
or to develop language like we did? Why would that happen?
Was it an accident? Ah-ha. Our habitat… provided a pressure
to develop language. Yes. -That’s incredible.
-Mm. So, in a way, we should be
really grateful that our ancestors
were so weak, they got pushed
out of the trees. [thumping] -Bang, bang.
-[laughs] [Michael] I’d invite you to be
a part of this interview, but you don’t have language. Right now. Mm-hmm. Quick decisions. Our ancestors didn’t have
that same pressure? Hmm. [Michael]The Cognitive
Tradeoff Hypothesis
suggests that in the dangerous
world beyond the trees,
early humans needed
to teach each other
and use abstract symbols
that could refer
not just to the immediate
here and now,
but to hypotheticals
and generalities.
Making room for that kind
of abstract thinking
meant sacrificing the immediate
and detailed memory
of their ancestors.Yeah. I’m able to imagine
past and future. I’m able to describe things
in an abstract way. And I don’t need the details, because I have the label. So it seems like a pretty good
trade-off. Yeah. Yeah. What a great message, right? Sharing is what makes us “us.” I would love to see your
working memory tests on chimpanzees in action. I would also really love
to participate myself and see how well I can do
compared to a chimpanzee. Yes. Have you ever had
a human and a chimpanzee compete like that
together? -[hooting]
-[Michael] They’re excited -about the idea too.
-[laughs] [gibbering] [Michael]
An opportunity to do the memory
task just like a chimpanzee
is really special.Who knows how it will go?Let’s see who shows up.-[clapping]
-[Michael] Yeah! You’re really good
at this, Ai.Looks like today,
it will be celebrity chimp, Ai.
Ai is older now,
and just like in humans,
her cognitive abilities
have decreased with time.
So I may actually
stand a chance.
To face off against Ai,I will be sitting in the booth
next to her.
Normally, her son Ayumu
plays against her.
But today, well,
she’s in for some Michael time.
I’m not your child, though,
am I?The tests are going
to get harder as we go along.
How will my memory compare
to that of a chimp
who never made
the same cognitive trade-off?
[exhales]In the first round,
the task is to remember
where each of the three numbers
are in numerical order.
But here’s the trick:as soon as I touch
one of them on the screen,
the other two will
be covered by solid squares,
so I can no longer see
where they are.
Now, well,
it’s up to my memory.
[Tetsuro]
Okay, let’s go. [Michael]
If I make a mistake,
I get an error noise
like this…
[buzzer]…while a correct answersounds like this.[computer chirps]When the chimpanzee
gets it right,
they are rewarded
with apples.
The human, me, well,
just gets the bragging rights.
I’m not getting apples. [laughs] [computer chirps] You really actually have
to focus more than I expected. Almost messed that one up. [buzzer] [computer chirps] [Tetsuro] How did Michael do? 95. [Michael]
On my first run,
I’ve managed to beat Ai.What is the next task? How many symbols? Whoa. [computer chirps] This is a lot harder.This game is similar
to the last,
but starts a little bit
differently.
This time, three numbers
appear on a blank screen,
but as soon as I touch
the first one,
the entire screen
is covered in boxes.
[computer chirps] Whew. [buzzer] [computer chirps] [buzzer] [Michael]
Ai… you having fun? -Whoa!
-[grunts]Ai is used to Ayumu, her son,
playing the game beside her,
so my presence
may be throwing her off.
I’m here for moral support, Ai.It was fun squaring off
against Ai,
but I want to see how I would
do against her son, Ayumu.
I’m ready. Okay… [Michael]Ayumu is currently
Matsuzawa’s best pupil,
able to ace the memory tests
at blazingly fast speeds.
[computer chirps]But today, Ayumu is not
interested in mental combat.
He’s busy flirting
with some young ladies
who live with him
here at the PRI.
And since free choice
is the guiding principle
of Matsuzawa’s research,
we can’t make him join us.
The good news is that
Ayumu doesn’t need to be here
for me to compete
against him.
The game can be presented
to me just as Ayumu does it:
with nine numerals.Let’s see if my luck
is the same against Ayumu
as it was against Ai.Oh, man. Okay. -[buzzer]
-Wow. [laughs] Even when I take time
I can’t do it right. Okay, more time. [buzzer] I thought I had that one. It takes a long time to memorize
nine numerals’ positions. [buzzer] It’s embarrassing
how long this takes me. I can do this one. [computer chirps] All right. Yeah. You don’t need
to laugh about it. Thirteen. I got better, yeah,
because you were pressuring me. Jesus. Six times worse,
six times slower. Yeah. I would love to. [Michael]This is the most
difficult test.
I have to remember all nine
numbers in numerical order
at Ayumu’s speed,which is to say,
I have to do
what I could
barely do before,
but now I have
to memorize them all
within the amount of timeit takes to blink.So I get half a second
to prepare? I’m going to prove you wrong.As a reminder,
this is how Ayumu performs,
which is standard
for a young chimp.
You got to be kidding me. -That’s way too fast.
-[buzzer] I got the first three. [buzzer] It’s like a joke. [buzzer] [laughs]
I don’t know where the 2 is. [buzzer] It’s too fast. Trying to think of this
very holistically. [buzzer] [clears throat] [buzzer] After the first three, if I see them,
I’m just having to guess. [laughs] [buzzer] Yeah. It’s impossible. Well, I hope this was
helpful for you. It was the first time you had
had a chimpanzee and a human together in the booth. What do you think–? [both laugh] If you ever need me
to study as a primate, -I give myself to you.
-Okay. Wow. And we need to make sure
to preserve them. -They’re already endangered.
-Yes. And yet they are our closest
link to understanding what we came from
and where we might go. [Tetsuro]
Mm. [Michael] It’s like taking care
of your family. -[Tetsuro] Mm, right.
-[Michael] Quite literally. [Tetsuro]
Yes. [snarling] [Michael]
The fact that humans alone
use complex
symbolic language
doesn’t make us any better
than any other species.
It just means that the path
we took required it.
In fact, in some ways
we aren’t better,
because we can talk.Today, we study those
who took different paths
as a way to learn
more about ourselves.
If we lose them,
we lose part of our story,
where we came from,who we are,and who we can be
in the future.
[gibbering] [shrieks]And, as always,thanks for watching.This season,
on
Mind Field. I will die. But should I? I want to perform
a reverse exorcism. There was like
a glowing figure, man. [man] I would love to do the Stanford
prison experiment again. There, let’s blast them again.
Number three. [electricity hums] Have you ever had a human and a chimpanzee compete
like that together? You having fun? -Whoa!
-No, not really. [shrieks] I am going to make
my hometown function like a brain. [cheering] Doing a good moral deed can
actually make you more likely to do something immoral. We’re going to see if we
can get people to allow a child to take the blame
for a crime they committed. -How old are you, son?
-Twelve. [guard] We’re going to need
to talk to the police. This facility is where you both
cryo-preserve people and store them. We have 159 patients
in these tanks. We’re offering an unknown
extension of human lifespan. -[Michael] You spied
on their dream.
-Yeah. That’s pretty spooky. [Michael] We received a message
from outer space. Please figure out
what this message is saying. -[man] You ready?
-I’m ready. Hey, I have to leave
and go over to the next episode, but you can come with me. Click below to check out
the next episode ofMind Field.I’ll see you there.

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