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.
One, two, three. 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. One, two, three.
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 chimpanzees memory be 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...
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 Chulcas, an acronym which stands for Chimpanzee Human Last Common Ancestor. Like us, Chulcas didn't have great natural offenses or defenses like blistering sprint speeds, protective shells, or claws, fangs, or venom.
So living in the safety of the trees was great. Those who stayed alive were able to survive. became the chimps we know today.
But for reasons we're still not quite sure of, some of the chulgas 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 symbols that can refer to things across time. Language. Many different types of creatures emerged with the chulgas.
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 savannah 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 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 trade-off hypothesis. Cognitive trade-off hypothesis is the culmination of decades of work by one of the world's leading primatologists, Professor Tetsuro Matsuzawa of 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 the monkeys. Look at spider monkey. Is there a baby on that one?
Yes, yes, yes, yes. Six months old baby. Six months, yes.
Showing the monkeys and apes in the tree. Yeah. High in the tree, that is the key. Because they live. That's where they live.
In their natural habitat. Can you do it? Ahhh!
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 habitat designed to mimic life in the wild. This habitat is home to Skylab, a working laboratory set high atop the chimpanzees'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's specially designed computer booths where a camera uses facial recognition software to recognize them and select a test based on that particular chimp's current familiarity with the task. Each trial takes about as long as 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... No, nothing. So what is for us a great way to collect data is for them an experience similar in many ways to what they would be doing in the wild.
There you go. 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? The beard is. Evidence tells us chimpanzee was so strong and continued to stay in the forest. We humans were not so strong. We were kicked out from the forest.
Aha. And coming down to the ground. to go into the dangerous open land where lions, cheetahs, and those carnivorous creatures.
We protect ourselves from the predator. Our habitat. provided a pressure to develop language. Yes. We have to collaborate each other as a group.
That's incredible. So in a way, we should be really grateful that our ancestors were so weak they got pushed out of the trees. We have succeeded to show extraordinary memory capability of chimpanzees. He is protecting... Bum, bum, bum, bum.
I'd invite you to be a part of this interview, but you don't have language. He doesn't need to have the language. So, Chinese mainly live in the world of here. Right now. And now, suppose that something happened in the bush.
You have to count up one, two, three, four, five. How many enemies there? To make a quick decision to go into the territory or leave to leave.
So that is the life of chimpanzees. Quick decisions. Quick decisions.
Our ancestors didn't have that same pressure? In the course of human evolution, we may have had this kind of capability, but we lost it to gain the new function, the language. Maybe memory and the language, the very rudimental form, was located in neighboring parts of the brain.
So to expand one area... area, another one must be shrunk. So putting all those things together to postulate my trade-off hypothesis of language and memory.
The cognitive trade-off hypothesis suggests that in the dangerous world beyond the trees, Only 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. I can think about the future of my child and their children. Yeah.
Chimpanzee do not have this kind of planning of the future. So the difference in one word is imagination. 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.
Yes. But how do we use the power of imagination? It's for sharing. Yeah. Helping each other, collaborating each other to raise the children.
Yeah. I understand chimpanzee mind. So that now I understand the unique feature of human mind and that is sharing.
What a great message, right? Sharing is what makes us, us. Yes. Sharing is the matter.
I would love to see your working memory tests on chimpanzees in action. Sure. 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? No, not really. So you are the rare person. I think they're excited about the idea too. 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. She sort of makes a mistake.
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. So why don't you try? To face off against Ai, I will be sitting in the booth next to her.
Now 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? 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. Okay, let's go.
If I make a mistake, I get an error noise like this. While a correct answer sounds like this. When the chimpanzee gets it right, they are rewarded with apples. The human, me, just gets the bragging rights. I'm not getting apples!
You really actually have to focus more than I expected. Almost messed that one up. Finished.
I 90%. How did Michael do? 95. 95. Pretty interesting. On my first run, I've managed to beat Ai.
So the next one is slightly more difficult. What is the next task? How many symbols?
No explanation because no explanation to I, no explanation to Michael. Get set, go. Whoa.
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.
The first one is secondary. So there. Finished.
Michael, congratulations. Ai? You having fun?
Whoa! She's nervous. She cannot do very well, so she got upset to you.
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.
So, would you like to try Ayumu's kind of memory test? I'm ready. Okay. Ayumu is currently Matsuzawa's best pupil, able to ace the memory tests at blazingly fast speeds. 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 Matazawa's research, we can't make him join us. The good news is that Ayumu is not interested in mental combat. 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 I. Ready, get set, go. Oh man. You may take a time as long as you want.
Okay. To remember nine numerals. Wow.
Jeez. Even when I take time I can't do it right. That's right. Even you believe that you remember, actually not. Take more time.
Okay, more time. I had that one. It takes a long time to memorize nine numerals positions.
And fail. It's embarrassing how long this takes me. I can do this one.
All right. Yes. Could you come here, please?
Yeah. You took a long, long time. Many seconds. Or you don't need to laugh about it.
16.9, 7.1, 7.0, 13.7, 0.0, 2.9. Mm, getting better. I got better, yeah, because you were pressuring me. But Ayumu, it's 0.5 second. So you always 2, 3, 4, 5, 6. Six times worse, six times slower.
So would you like to try Ayumu's speed? Yeah, I would love to. OK. Please go ahead.
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 time it takes to blink. 0.5 seconds.
So I get half a second to prepare. And it's impossible. I'm gonna prove you wrong. As a reminder, this is how Ayumu performs.
which is standard for a young chimp. Okay, let's go. You gotta be kidding me.
That's way too fast. I got the first three. Good boy.
It's like a joke. Ah, I don't know where the two is. It's too fast. I'm trying to think of this very holistically. After the first three, if I see them, I'm just having to guess.
So you recognize that you cannot do just like a human. It's impossible. 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. Yes. What do you think? It was fantastic. It was so interesting.
You chimpanzee and Michael. If you ever need me to study as a primate, I give myself to you. OK.
Not many people recognize the history of studying chimpanzees is very short. In the world, only 60 years. Wow. But chimpanzees survive 50, 60 years.
So this means we need the patience. Chimpanzees are classified endangered species. So to pass those treasures to the next generation, now we have to do the action.
We need more information from chimpanzees. To continue the research to know more about the chimpanzees. They are evolutionary neighbors, cousins.
So the comparison of different species let us know the evolutionary origins of many kinds of human traits. And we need to make sure to preserve them. Right. Conservation.
They're already endangered, and yet they are our closest link to understanding. What we came from and where we might go. It's like taking care of your family.
Right. Quite literally. Yes.
My hope is you prepare the message to the people, what you have witnessed, what you have experienced. That is human because the key word is sharing. 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. 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. I would love to do the Stanford prison experiment again.
Derek, let's blast him again. Number three. Have you ever had a human and a chimpanzee compete like that together? You having fun? Whoa!
No, not really. I'm going to make my hometown function like a brain! 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. We're gonna need to talk to to the police. This facility is where you both cryopreserve people and store them.
We have 159 patients in these tanks. We're offering an unknown extension of human lifespan. You spied on their dream. Yeah.
That's pretty spooky. We received a message from outer space. Please figure out what this message is saying.
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 of Mind Field. I'll see you there.