 Konnichiwa. Good afternoon. Science is a human and conducted by people in many nations. This afternoon, we bring you a member of that community, Dr. Tetsuo Matsuzawa. Dr. Matsuzawa received his undergraduate degree and his PhD from Kyoto University and he has been a faculty member at the university for the past 20 years. He currently holds the position of full professor in the Department of Behavioral and Brain Sciences at the Primate Research Institute, where he continues a tradition of primatological research that dates back nearly 50 years. Dr. Matsuzawa's research interests include the mental and linguistic abilities of chimpanzees, tool use by wild chimpanzees, the development of behavior in primates, and cross species comparisons of cognitive behaviors that include humans. He has published numerous articles in a variety of scientific journals including the International Journal of Primatology, Primates, the Journal of Comparative Psychology, Behavioral and Brain Sciences, the Journal of Human Evolution, Nature, and a variety of others. He's also been a contributing author for several books including Understanding Chimpanzees, Chimpanzee Cultures, and Great Ape Societies, to name just a few. Some of Dr. Matsuzawa's studies on cognition have revealed that chimpanzees and humans categorize complex geometric figures and perceive colors in similar ways. That chimpanzees show a preferred word order when describing objects. And that chimpanzees can accurately identify the faces of fellow chimps and humans. But they recognize chimps faces faster than human faces. Perhaps to a chimp, we humans all look alike. Some of his studies on tool use have revealed that chimps can recognize the tool value of different objects, that they can learn complex tool-using behavior by watching other chimps, and that a tradition of tool use in one community can be transferred to a different community with the relocation of an individual. In a forward to a book titled Understanding Chimpanzees, chimp researcher Jane Goodall wrote that understanding the behavior and cognitive capabilities of chimpanzees would be, to a large extent, determined by the imagination and sensitivity of the people who are working with individual chimps. Dr. Matsuzawa's imaginative research exemplifies the search for knowledge and understanding through scientific inquiry. In today's lecture on chimpanzee intelligence in the laboratory and in the wild, he will integrate the findings of laboratory studies on the cognitive skills of captive chimpanzees with field observations made on chimpanzees in the wild to present a more unified view of chimpanzee intelligence. Dr. Matsuzawa. Thank you, David. It is my great pleasure to be here to talk about my studies on chimpanzee intelligence. I have been working with chimpanzees for 19 years. I wanted to make a bridge between the study of chimpanzees in the laboratory and the study in the wild. Japan is a special country in terms of the study of non-human primates. Why? Because there is an ingenious native species called Makaka Fusukata, you know, Japanese monkeys or snow monkeys in the country. And we have many primatologists. In east of fables, Grim's Fairy Tales or Mother Goosey's Naturally Rhymes, monkeys do not appear in those fairy tales simply because there is no monkeys and apes in Europe and in North America, even though there are many primatologists. Monkeys and apes, they live in Africa, Asia, and Central and South America. Let me tell you the simplified version of the hyalogeny of humans and monkeys. I think all of you agree that humans and monkeys at present, they are different to each other, but we share a common ancestor in the past. Well, the fossil record tells us that it should be about 30 million years ago, but forget about it. Here comes the chimpanzees. Now the story is somehow complicated. Many people still misunderstood the position of chimpanzee. The common ancestor descended to humans and monkeys, and the line of monkeys deviated to various kinds of species. Among them, the most intelligent species should be the chimpanzee. That is totally wrong, incorrect. The correct hyalogeny, correct branch is as follows. Chimpanzee, oh, let me tell you this way. The common ancestor descended to ape-like creatures called hominoid and monkeys. Then the hominoid divided into two, one is human, another is chimpanzee, about five to six million years ago. So this is a correct hyalogenetic relationship among humans, chimpanzees, and monkeys. Nakedness, it's not uniquely human. This is an infant chimpanzee a week just after the birth. Naked, the body weight is about less than two kilograms, and they are in the mother for about nine months in comparison to 10 months and three kilograms in the case of humans. If you have a chance to raise an infant chimpanzee in your house, I'll bet you you will be fascinated by the resemblance between the two species. One is my daughter, another is not mine. I got a job in 1976 in the Primary Research Institute of Kyoto University. In 1978, a long-term project about chimpanzee intelligence started in 1978. The main subject named I, spelled A-I, and pronounced I. I is the most popular name, the most popular girl name like Seara or Emi, I don't know, but anyway, so such a kind of name in Japanese, and means love. So she's now 19 years old and become 20 years old in October. I, with the other 10 chimpanzees, so I mean 11 chimpanzees in total, kept in a group, living an outdoor compound like this with stream, with trees, and when I do the experiment, each chimpanzee has its own name and they are invited to get into the experimental booth. And she is the first chimpanzee who learned to use Arabic numerals to label the number of objects and the number of dots. So let me show you what kind of skill she has. The first video, please. To counting dots, shown on the computer screen. Now at the age of 14, she is the first chimpanzee who can name the number from one through nine. Her accuracy is above 95%. Thank you. Using the same method, human subjects were tested. The response latencies were plotted against the number of dots. So if you compare the response latency, humans and chimpanzee, the latency is plotted against the number of dots. So the chimpanzee is much faster than the human subject. The chimpanzee can not only use Arabic numerals. Okay, stop, please. Not only the task like this, but also she learned a various kinds of task. She learned to discriminate 26 letters of the alphabet. And then the letter is used for naming individual humans and chimpanzees. Next. Well, the picture upside down is a bit difficult for us to recognize, but it's not the case of chimpanzees. They can easily detect who he is. She can label the color to a visual symbol. She can label the color to kanji characters which is used by Japanese people. Of course, the reverse, so she can decode the kanji character to the corresponding color. And she learned a lot of kanji characters like this. Each pattern has its own meaning. Putting things together, she can label, for example, when I presented five red toothbrushes, she can answer the number, the color, and the object name by using Arabic numerals and visual symbols. Not only combining the visual symbols, but also she can construct a visual symbol from the elements, from the scratch. Besides the learning task like this, I'm testing what I say, praying with a chimpanzee after the lesson. In this case, she's drawing one of the masterpiece and people think that chimpanzee cannot draw concrete image. Yeah, I think it's true, but I devised a test to show their ability. It's a simple test. Giving a child book to the chimpanzee rather than a white paper. What she did, no training, no previous experience, but what she did is she spontaneously checked all the people standing on the truck waiting for a train. So what it means, she really recognized what is drawn on the child book. The chimpanzees also pray with cray for 30 minutes without any kind of direct food reward or something like that. So they have intrinsic motivation to the arts like drawing or cray. They also help us to clean up their cages because of the shortage of human labors in Japan. It's a joke. So there is another story of chimpanzee intelligence as well as bonobo intelligence just described by Susabay Jirambu this morning. After 10 years, my study on chimpanzee intelligence in captivity, a question came out. I know they are very smart, very intelligent. So how their intelligence is utilized in their natural habitat? That was my simple question. So 10 years ago, 1986, since then every year I went to Africa to study the chimpanzee intelligence in the world. But I'm not the field worker like Richard Rangan, so it's very difficult to know their intelligence in the world. For example, can you see the chimpanzee in a tree? Left, top, tiny figure, can you see it? Yeah, it's very difficult to observe the chimpanzee. So I had no idea to test the chimpanzees in the wild. Then what I recognized, they are very intelligent very skillful in the tool use in the wild. In the case of Bosu, this is a research site of mine. The chimpanzee use a pearl of stone as a hammer and anvil to crack open oil nuts. But the oil nuts is very important plants for the villagers, planted close to the villages, so that when I try to see the details of the behavior, chimpanzees are very timid near the village, so just run away. Or under the palm trees, dense bushes, so you cannot see the details. So what I decided is to make outdoor laboratory to see the details of this unique tool use behavior. So in general, I recognize the similarity between the symbol use, which I have studied, and the tool use in the wild. Suppose that there is an actual apple. Apple can be labeled by a visual symbol. Apple beyond reach can be retrieved by a stick. So symbol use and tool use has a similar structure. So the outdoor laboratory was open on the top of the hill in which I brought stones and nuts and waited for the chimpanzees behind the screen from seven in the morning till six in the evening. So this is oil palm nuts and stones identified by me, prepared in the outdoor laboratory. So it's a kind of field experiment. Through the longitudinal study, I recognized the development of the tool use skill. The number of chimpanzees who succeeded to use a pair of stones as hammer and anbill, the number is, relative number is plotted against the age. So at the age of three and a half years old, they start to use the stone tool. Less than three and a half, they cannot use a pair of stone as a tool. This is a typical set of tool, anbill and the hammer. And I found very interesting examples four times. In this case, a set of three stones are used. The third stone beneath the anbill stone, the wedge, support the anbill stone, flat and stable. You can see the actual one in the center so that exactly the same method in the laboratory I brought back the three stones to the village to test human children. So it's a kind of three stone problems given to human children. Five years old girl, she tried to fix a nut on the anbill by pushing the hammer against it. But when she tried to hit, a nut is rolling down. So this is not the adequate way to solve this problem. Another boy, six years old, he tried to hold a nut by left hand. He must be careful. Then he reached the solution. Exactly the same to that done by chimpanzee. The third stone is used for the wedge. The wedge stone is not exactly a tool. It's a tool for supporting the other tool. So I named the third stone meta tool. Let's see the structure of the tool and the meta tool. Again, we can find the similarity between the symbol use and tool use. Let me see, near sight. Suppose that there are five pencils. As I have described, chimpanzee can coded five pencils to pencils and five. A set of visual symbols is used to represent the reference. In the same way, the target object, in this case nut, can be cracked open by a set of tools, hammer and anbill. Moreover, five red pencils can be coded by the three visual symbols, five red pencils. In the case of eyes naming, she spontaneously developed her own favorite word order, word order, like color, object, and then number, or object, color, and then number. Anyway, the number is located in the last position. In the case of tool use, nut can be cracked open by a set of three stones, ambileses supported by wedge. On it, there is a nut, is hit by a hammer. If you look at the developmental cause of the tool use or the acquisition process of the tool use, well, I think there are a lot of things to be told, but mother, they have very important law for the offspring to acquire that skills. So always the mother or the other members of the communities are nearby, served as the model. When I first saw the chimpanzees in the wild, what I was so impressive was the strong bond between mother and the offspring. And here I want to introduce you an episode which shows the strong bond between a mother and her daughter, two-and-a-half years old named Jokuro. Jokuro, two-and-a-half years old female, she has older sister named Jya, eight years old and the mother, Jire. So Jire, Jya, Jokuro, mother, older sister and the infant, always moving around together. It was 1992, January. The infant seemed to get, got the flu and weakened and died. And it was a dry season, so the dead body was mummified. Let me introduce you the video describing the episode. Could you turn, yes, sound up please. So look at the infant. The mother touched the forehead, just like checking the fever. One, two, three. Can you see it? So January 12th, mother and the infant came to the outdoor laboratory. This is the by-product of observing the two-use kill in the outdoor laboratory. Two-and-a-half, still suckling the nipple. The weaning is about two-and-a-half in the case of chimpanzee, much longer than modern humans. So at the weaning age, the infant should eat more, but she did not eat and just sit. Now the elder sister went to the infant to pray with, to cheer up, take the hand while waving the branch. And one day, it was also impressive for me, the infant approached the mother to groom. In many cases, mother groomed the infant. The reverse is rare, but the day the infant tried to continue to groom the mother. Look at the center. I happen to witness the infant fall down on the ground. Then the elder sister went to the infant to get up, still alive, and then mother went to the infant and bring up the arm, and the infant herself went on the back. So all is filmed in the outdoor laboratory, where I'm waiting from the very early morning till the evening. So it's a kind of sampling of the dying process and after the death. In January 20th, nothing the infant did, just crouching, sitting. January 23rd, the rear, now the infant no more grasped the mother, so upside down, then the mother put the infant on the back and the infant can grasp. I tried, actually I tried to give nutritious food for the chimpanzees. Then January 20th, I recognized that she died. Now the mother pulled up the arm and with the neck and shoulder hold the arm, so the figure is just like the infant is alive and cringing on the back. So two days after the birth, after the death, so the body is rotten, smelled badly, and the infant, the way of carriage is somehow funny, so backside, so supine, and the next day, supine and upside down, so totally wrong way of carrying the infant. So I suppose that the mother gave up the infant, I thought so, but the fourth day after the death, the infant turned to be mummified, but now the way of carrying the baby is returned to more normal way. I mean the mother take the arm and put it between the neck and shoulder and carrying the infant. And the other members just accept the mother and the infant. Day by day, the infant was dried up but the attitude of the mother to the infant was not changed. Now it's February 1992. The rainy season is approaching. The safari ants came out. Now 15 days after the death, the dead infant no more suckled the nipple, so the hormonal change occurred and the menstrual cycle recovered. So in a sense, the mother is ready to have another baby, but she never gave up the dead infant and chasing the fries, just like me, and grooming the faces. It reminds me of just one year ago before, so when she was alive, the mother gloomed the infant. Now the estero cycle recovered and the bottom swearing, pink swearing, appears so that the males of the community try to coach ship, coach ship display, try to invite young males. And one day, I witnessed a very unusual scene. Alpha male using the dead body as a tool for the display. He is actually the biological father. After he used the dead body as a tool for charging display, while all members scattered, I took the picture of the mummified infant, except lower jaw, everything was intact. Then the mother came to pick it up on the back as usual. So 16 days before the death and 27 days after the death, I continuously observed the dying process and the deaths and the responses to the deaths of the chimpanzees. Jokuro, the infant, is named from this huge tree Triplociton, scientific name, and the local name is Jokuro. Thank you for the video. Let me add another interesting part of this episode. This is just coincidence. Logdall episode, as just Richard Wrangham described. So Logdall episode in this case is 80 years old female, the sister of the dead infant. Before the death, the mother carried the sick infant and moving in the tree followed by the sister. She stopped at a point and broke a branch to make a log. 10 cm in diameter and the length is about 50 cm. I think you can see the chimp holding the log by the hand and the leg. So it seems to me, now the sister is carrying the log like this or like that, or when she stops on the branch, balance the log and tap softly. It seems to me it's a pretense of taking care of the sick infant. The reason is this is the real Logdall played by the native Manongar. So they use log as a door. There is only one difference. On the top of the log, there are hairs. We know chimpanzee use tools, various kinds of tools. Jane Goodall found termite fishing in 1960, 36 years ago. And people know that chimpanzee do the termite fishing, but it's not true. Chimpanzees in Gombe use a trick to fish termites in the termite mound, but the chimpanzees in Bossu, my research site, they eat termite by catching termites by fingers, but they do not do the termite fishing. On the contrary, chimpanzee in Bossu use a pair of stones to crack open oil permanates. But the chimpanzees in Gombe, they eat oil permanates, out of soft red tissue, but not use a stone tool, because stones are available. So each community has a different type of tool and tool use. Last year, I, with my graduate students, found a new kind of tool. It's called algae scooping. Chimpanzee use a stick to get the algae on the pond. Let me show you the video. The second one, please. And in this case, I happen to take the film of the process of making the tool. Look at the four years of female get into the bush to get a pond, break it, and then cut into the length of 50 cm and strip the leaves. Now there are tiny hooks. So another chimpanzee in the pond, he use a bit longer, thick, straight, without hook, stick to get the algae. Thank you. What we found is the chimpanzee utilize two kind of sticks. One is thick and relatively long, right side, and another stick made of foam, flexible, short, thin with hook. It's good for getting the patchy algae. So the long one is mainly made of a kind of ginger and the flexible one with hook is made from foam. Now I recognize each community of chimpanzees has a different traditional way of using tools so that I decided to go to the azation community. In this case, from Bosu, 10 km away, there is a mountain named Nimba. Actually it is located in the neighboring country, Ivory Coast, not in Guinea. Nimba is the mountain covered by the primary forest and there is no base for the field study so I decided to sleep in the mountain. I spent two weeks to follow the wild chimpanzee, non-habituated chimpanzees in Nimba. Then I found very interesting different cultural tradition in Nimba community. Here is one example of making a nest on the ground. Above the altitude of 800 meters, they made one third of the nest on the ground. Chimps used to make the beds in the tree and they also cracked open cola nuts, cola eduaries, cola nuts, instead of oil palm nuts. So I decided to do another field experiment on social transmission of cultural behavior. What I did is bring back the cola nut to Bosu chimpanzees and give them the cola nuts. So you can see the three round green cola nuts in front of a huge male. They neglected, they neglected this unfamiliar round green nuts. Some of them tried to eat, mean sniff, bite, and just throw away. And since then, they just neglected, except one adult female named Yoh. She had no hesitation to crack open cola nuts. And the young members of the community carefully observed the behavior. So the plausible explanation is as follows. Yoh, in the case of chimpanzee society, we believe that chimpanzee females emigrate from their own community to the adjacent community, male remains. So the plausible explanation is Yoh was born in Nimba, and in Nimba community she learned to crack open the cola nuts to eat. And she emigrated, she transferred to the Bosu community after the puberty before getting the first child. And she found no cola nut there, but the experimenter provided the cola nuts so she was happy to crack open the cola nuts. So the culture, in a sense, can be transmitted by emigrant females between the communities. And the culture can be transmitted from one generation to the next, not by the adults, but by the young members of the community. That is the general idea of social transmission between the communities and a closed generation. So through the study of chimpanzees in the laboratory and in the wild, and I intended to cross the main research method like laboratory studies usually use experimental analysis and field studies based on behavioral observation, but what I did is experimental analysis in the field and why not behavioral observation in the laboratory. So the research target is to use leaves for drinking water in the wild. And what I did is to simulate this behavior to know the details of the social transmission among chimpanzees in captivity. I will show you the video of this experiment, but before that, I want to give concluding remarks about a series of experiments and the evolution of intelligence. The intelligence used to be divided into technological aspects like symbol use and tool use, pitted against social intelligence, like just described by Franz Dubal yesterday. We know chimpanzees in Gambit highly social. Bonobos in Wamba highly social. Not only chimpanzees and bonobos, Japanese monkeys, the other non-human primates, all is social animal. So humans, chimpanzees, monkeys, we share the social intelligence. It means the social intelligence, the characteristic, which was in the common ancestor of humans, chimpanzees, and monkeys. But the technological intelligence like symbol use or tool use cannot be found in monkeys. It can be found only in humans and chimpanzees or the great apes. So it means the technological intelligence originated from the common ancestor of humans and chimpanzees. So what is uniquely human? My opinion is the self-embedding structure of cognitive capability. What it means? I'm communicating with you about the communication. My brain can think about the brain. We have the language, which describe about the language. We have the knowledge about the knowledge. Well, the chimpanzee, they can use a tool, meta tool, a tool for another tool. But humans can use a tool for another tool for the third tool, for the fourth tool. So the depth of self-embedding structure should be different between the two species. Well, in the last part of my presentation, I'd like to show you the video what's really going on in the laboratory. So this is Japan, Japanese castle. And this is the primary research institute of Kyoto University. It's not in Kyoto, 80 miles away from Kyoto. This is the main subject named Ai. She's now 19, 20 in October. So this is a kind of matching to sample task to select the identical picture. But the sample is upside down. And she's very good at to choose the correct one. She's on the way to memorize three digits number. And this is another chimpanzee named Han. The task is easy, match the color, but the reward is a coin, a dollar. And after she got four, five coins, she put it into the vending machine to get a piece of apple. It costs a dollar. Even in Japan, it's too expensive. In 1986, I went to Africa to know the intelligence how it is utilized in the wild. This is the outdoor laboratory for the field experiment of nut cracking behavior. There are a lot of new findings like hand preference. They have perfect hand preference. Left handers use left hand always for Hanla. This is outdoor compound with trees and a stream with gold fishes. And the chimpanzees do not damage the flowers. So we have already done the three-year project of planting trees in the compound, and we succeeded. They are allowed to eat. They actually eat some of the trees, but they do not eat like coniferous trees. In the single subject situation in the indoor experimental booth, everything is controlled by the computer. This is the matching to sample of color. So color is matched to orange goes to orange. Easy task. And she can code the color to visual symbol. The lexicrams we devised originally. So she says white. And each visual symbol corresponds to the color and also the Kanji character. We have Kanji character. So in recent years, we shifted to Kanji characters because it's much easier for Japanese to understand what's going on. So she can, in a sense, she is bilingual. So she can code the color to Kanji characters. And she can name the number of dots by Arabic numerals. Not only naming the number, but also she can choose the small number first to the large number. Four, five, six. After training the adjacent number, the skill transferred to non-adjacent number like two, four, five, one, six, nine. And I concentrated on the single subject situation. But in recent years, I'm doing face-to-face situation test. So this is the study about imitation. We know that it's very difficult for monkeys to imitate. And we know that chimpanzees can imitate. But the question is how they can imitate? What is difficult? What is easy for them? The subject is pen. Twelve years old. I can do test the subjects. Eight subjects are out of eleven chimpanzees in this situation. She got it. Social praise. Give a piece of apple. I didn't get any one dollar. Here comes the second chimpanzee. Very good. She came from Paris. So I'm using all the techniques like verbal instruction, pointing, molding and so on. And I want to know the answers to the question I raised. Here comes the third chimpanzee. It's eye. Good. She can't stop it. It's totally up to the chimpanzee. So she's free to do anything. And she started to pray with the water. And in Bosu Guinea, West Africa, I have been working with the wild chimpanzee to use. Here comes the chimpanzee eating the fruit. There are only about twenty chimpanzees in the community. They have to cross a road from one forest to the next. And this is the field experiment of nut cracking. I prepared the stones and the nuts. So the number of stones available is controlled by the experimenter. And this time I was lucky enough the chimpanzee already waited for me and they select a pair of stones. And I record who used which stone. In the case of young chimpanzees, she cannot decide which stone to be used. Let me tell you briefly about the development of the stone tool used. The first stage is getting the kernel, edible part of the nut from the mother. And then the infant started to manipulate the nut by him or herself. Or manipulate the stone and carefully watching. This case, not mother, but adult female. Carefully look at the skill. So then she pick up a nut, place on it and stamp. And then pick up the broken piece to eat. So she mimic whole image of the process. But no hammer stone. And at the age of three and a half years old, changing the hammer succeeded to crack open the nut to get the kernel. So now I'm ready to do the simulation experiment in the enriched compound in captivity. Here is the dome or outdoor booth. Through the underground tunnel, I can get into the inside of the booth. So the traditional idea is just inside of the booth, there is a tester and apparatus. And I pour the juice from the inside to the outside. And many materials are available, but the chimpanzee, one of the chimpanzee invented to use a kind of jennifer as a tool to get the juice from the artificial tree follow. So the captive chimpanzee just like as wild chimpanzee, they showed high selectivity of the material. So all the chimpanzee use jennifer, although there are many trees available. Besides the outdoor experiment, I keep going the experiment of single subject. This is tracing a step for writing. Two chimpanzees, I and Pendeza are serving as subjects. They have to trace exactly the white thin line. So at the end of a niche, I feel that chimpanzee intelligence is still underestimated. I think we should continue to make the efforts to understand the chimpanzee intelligence. Well, 36 years ago, Jane Goodall started the long-term study of wild chimpanzees. However, we know chimpanzee, they survived 40, 50 years. It means no one has ever seen the whole process of a chimpanzee from the birth till the death. No one has ever seen it. So, let us try to make the effort to understand the chimpanzees and the great apes and to protect their natural habitat in the coming century. Thank you. So, yeah, assemble 16. So we'll just go 15 minutes now. We'll be out at 5.15. Tell them that. I think so. We have time for some questions. We have about 15 minutes. Please submit your questions to our assistants and they'll bring them to the front. Before we begin the question and answer session, we'd like to bring to your attention a handicap card that was found in the parking lot. And if this belongs to you, you can claim it at the front table. Any reaction from our panelists to the previous presentation? Dr. Romba. Congratulations on your very elegant presentation. What I would like to ask is did you have any evidence of the mothers actively trying to teach the young to crack nuts? Well, in my case, I say no. And definitely no. I started a field experiment of nut cracking in 1987. Since then, each year, I spent a month or two months and cumulative record is 80 hours observation of nut cracking in the outdoor laboratory. And we have no instance of so-called active teaching. Like, here we are. We're molding the hand or given that. But there are a lot of evidence more interesting ones like an infant stole not the kernel but the nut to be cracked. Stole the nut and by himself tried to crack open. Or put a nut on the amber stone of the mother to see how it is cracked open. So the infant himself prays and not on the amber of the mother. And those behavior reminds me of sushi master in Japan. Japanese people like sushi. I hope you know what it means. Rice and raw fish. Sushi master make very beautiful sushi. And the students they are allowed to observe the behavior. For two years, for three years they are not allowed to even touch the rice or the fish. They wash dishes, wash towels and carefully observe the sushi master making sushi. Then two years, three years later one day sushi master says okay it's your turn you may use the utensils, rice, fish and the student can do it very beautifully. So traditional skills cannot be transmitted not always by active teaching or manual. It's not like McDonald's hamburger so sushi is something different, very skillful. For I believe active teaching is not the best way or not the most advanced way of teaching. I have a question about the age of development of the tool use. You were drawing a parallel between tool use and symbol use. And Sue I think and Dwayne said that the time of learning language and linguistic abilities is early before three and a half. And you don't have it until three and a half but you have weaning at two and a half. So maybe they already are interested in eating the nuts earlier. So why do you think it seems so late? Good question. I really appreciate Richard as I told in my presentation nut cracking is a tool use but a special kind of tool use in my opinion in terms of here logical level because the target object a nut is cracked open by a set of tool. Not a single tool. So the level is one step deeper. If you look at the other kinds of tool use in Bosu like they do ant dipping use a stick to catch an ant or use leave. It's not sponge but folded to get the water in the tree for all single object to the target and pestle pounding I do not give you the detail explanation and algae scooping newly found. Now we know the minimum age for these tools are two and a half. In the wild we observed two and a half years old already started to use in my nomination level one tool only one relationship between the target and the tool. So level one tool is start at the age of two and a half but in the case of nut cracking one step complicated. So that is my explanation why it starts at the age of three and a half. I was fascinated by the account of the death of the infant and I wondered if this long period of what we might call the mother's grieving for days is that a typical kind of event with every day or just does this just apply to infants or when older chimps die is there also a kind of long period like this? How representative is this? I think it's atypical. I mean I have never seen such a long episode of carrying the dead body. There is one in Mahare. Anyway, I don't say all the mothers behave like that. I think in this case there should be some factors like the infants died at the age of two and a half means the age of winning means relatively independent from the mother so the infant started away from the mother so the mother even after the death of the infant it's normal for the mother to away from the infant so actually after the death she sometimes spent sleeping with the males for a while then going back to the infant to take care of the dead infant so two and a half years old it might be one factor and of course in dry season the dead body was mummified if it was not mummified lose the arm, leg, skull still keeping I can't imagine such a thing so the whole image of the body was intact except lower jaws that might be an important factor and there should be the personality of the mother I don't know why in this particular female but anyway the complex factors like these produced an episode like this we have a question from the audience I would like to make a connection between Tetsuo's work that he has explained so nicely here and social behavior and I'm sure he's aware of the connection so it's not for his benefit but it's more for the audience's benefit all these issues of how deep a level of tool use is being used for example to use two tools to crack one nut or to use even three stones to wedge the anvil stone and so on all that sort of behavior can be parallel in social behavior as well in social situations you also see such things as mediation where one female brings two males together or where one male breaks up a fight between two females is also dealing with the situation of objects A and B outside of himself and making a sort of connection between the two and just to give one example where you can sort of see the connection where these higher levels come in you can have a situation where for example a male and a female are copulating and a lower ranking male comes in and that's his preferred female and he will go to the alpha male to get him to break up those two and so that's a very similar sort of situation where they make links between objects outside of themselves and connect them in some way and it's basically the same mental process I think that's going on that's also why I'm not completely sure that technical and social intelligence can as easily be distinguished as some people say because I think a lot of the connections that are being made are very similar sort of connections would you agree with that? I really appreciate Franz complimentary remarks that is my point in my conclusion what is uniquely human I told that self-embedding structure such a kind of intelligence on intelligence should not be domain specific it should be domain free so not only social intelligence but also technological intelligence what uniquely human is the self-embedding structure means if you talk about the social aspect I know that Richard know that Franz suspect that Sue frapped doing last night I don't know that is true or not but we can think about the other mind or even we can think about the other mind thinking about the mind of the third person thinking about the mind of the fourth person so this is exactly what I wanted to tell you so the self-embedding structure the nature should be domain free one question from the audience have the chimps ever been observed using the stones as weapons yes many times especially by males alpha male used to use slow the hammer when he during cracking nuts something fight happened he throw under throw the stone or young males they used to fight against about females in this case also well he usually bend the branches or throw the branches but they also throw the stone to the females and of course toward the human observer too does I have a concept of zero good question yes actually she knows the numeral zero she can discriminate zero from the other numerals and actually she is on the way to learn the number ten in this case ten is represented by one zero so she knows zero as a figure but I have never told the meaning of zero because it's a very interesting research theme so what I wanted to do is well it's always my way but I need very strong evidence I want to have very strong evidence that the chimpanzee can understand the concept of zero so what I have intended to do is after teaching ten, eleven, twelve she can put the two numerals together to represent a certain number and that particular numeral can be used in a different way to express the concept of zero so in the long term project yes I want to test the concept of zero but not yet on behalf of Gustavus Adolphus College and the organizing committee I'd like to thank our panelists for their participation in this Nobel conference and for presenting such a thought provoking series of lectures we wish you all you in the audience a safe journey home and hope that you'll come back to next year's Nobel conference on unveiling the solar system thank you all