Q & A
Tetsuro Matsuzawa is a professor of Kyoto University, Japan, and, since 2006, director of the Primate Research Institute (KUPRI). He is known for his research on the chimpanzee mind both in the laboratory and in the wild. His laboratory work consists of the Ai-project, which focuses on language-like skills, number-concepts, and memory ability in chimpanzees. The project is named after Matsuzawa's main research partner: a female chimpanzee named Ai. Launched in 1978, the Ai-project is one of the longest running laboratory research projects. Matsuzawa has also studied tool use among the wild chimpanzees of Bossou, Guinea, West Africa since 1986. The Bossou chimpanzee community has been followed by KUPRI researchers for more than three decades. Bossou chimpanzees are well known for their use of a pair of mobile stones as hammer and anvil to crack open oil-palm nuts. Matsuzawa has been attempting to synthesize his field and laboratory work in order to understand the nature of chimpanzees, our evolutionary neighbors. He has received several prizes during his career to date, including the Prince Chichibu Memorial Science Award, the Jane Goodall Award, and Japan's prestigious Medal with Purple Ribbon. The following two books published by Springer are recommended: Primate Origins of Human Cognition and Behavior, and Cognitive Development in Chimpanzees.
Why did you become interested in chimpanzees?
My major at undergraduate level was philosophy. I wanted to know about various aspects of the world: biology, chemistry, history, language, and so on. I could not focus on a single discipline. I thought that philosophy would somehow contain all these subjects. However, students of philosophy were obliged to learn German, French, Latin, and Greek in the first two years of their studies because all the important books were written in those languages. I became bored with looking at black patterns printed on white pages. I preferred climbing mountains, where I could directly contact nature. For four years, I spent about 120 days a year climbing mountains and became a member of the Academic Alpine Club of Kyoto (AACK) team. In 1973, we first climbed the West peak of Kangchenjunga, the third highest mountain in the world. During my mountaineering days, I gradually came to recognize what the question that really interested me was.
Many disciplines try to understand various aspects of the world. However, the world is perceived through our sensory organs. My question concerned the constraints of the human way of thinking: how do we perceive the world? I decided to leave philosophy and became instead an experimental psychologist, analyzing human binocular perception. Then, I recognized that it was not in fact the eyes but the two hemispheres of brain that really saw this world, so I shifted to neuroscience, examining brain activity in rats in graduate school. This career helped me to get a position, in 1976, as assistant professor at KUPRI at the age of 26. I now wanted to know how nonhuman primates see the world — a unique window into the evolutionary basis of the human mind. A year later, KUPRI launched its own ape-language-like project. The first chimpanzee, Ai, arrived in November 1977. From then on, every single day was unique and memorable for me. I was amazed by each new finding and experience through my daily interactions with Ai. In that sense, it was she who guided me to various questions about the chimpanzee mind.
Why and how did you start the field work of wild chimpanzees?
My first scientific paper on the Ai-project appeared in Nature in 1985. It reported that Ai had learned to use Arabic numerals to represent numbers. She had also learned letters corresponding to 10 different color terms: color classification by the chimpanzee is very similar to that in humans. Having gone some way to understanding chimpanzee perception, I decided to take a sabbatical leave, which I spent at the University of Pennsylvania. David Premack was my mentor there. He is a well-known psychologist who coined the term ‘theory of mind’ — understanding the minds of others. While based on the East-coast of the USA, I took a trip to West Africa to visit Bossou where one of my KUPRI colleagues, Yukimaru Sugiyama, had begun his survey of wild chimpanzees. I was motivated by a simple question: how is chimpanzee intelligence employed in the natural habitat? Compared to climbing in the Himalayas, a trip to Africa was easy for me.
Why did you start combining field work and laboratory work?
After my initial experience of fieldwork in Africa, I was invited to the first conference that brought together chimpanzee researchers from all over the world, ‘Understanding chimpanzees’, held in Chicago in 1986. The meeting aimed to celebrate the publication of the landmark book The Chimpanzees of Gombe by Jane Goodall. She became another mentor of mine. With help from interactions with Premack and also Goodall, I looked for my own intellectual niche. The simple answer was an attempt to synthesize my two mentors' approaches, in order to understand the chimpanzee as a whole.
What came out of combining two different approaches?
In Africa, I was fascinated by observing various aspects of chimpanzee life, especially their sophisticated way of making and using tools. I focused on the stone tool because it is the most complex form of tool use ever observed among wild chimpanzees. It is also related to lithic technology, which played a fundamental part in hominid evolution. Thanks to my background as a laboratory researcher, I decided to develop a ‘field experiment’. I provided stones and nuts in a clearing in Bossou forest and waited for the arrival of chimpanzees to this ‘outdoor laboratory’. It worked. The field experiment dramatically increased our opportunities for observing and video-recording chimpanzees' use of stone tools for nut-cracking.
My colleagues and I have continued recording stone tool use and the use of leaves for drinking water at Bossou's outdoor laboratory ever since. Twenty-three years' worth of annual long-term research has provided interesting findings, such as: individuals' hand preference when using hammers; a critical period for learning to nut-crack at around 3 to 5 years of age; the role of ‘education by master-apprenticeship’ and observational learning; episodes of deception; cultural variation in neighboring communities; and clues to how immigrant females are responsible for cultural propagation between communities. I often observed hard pounding of tools resulting in an anvil stone being broken into two halves. Later, the broken half would be used as a hammer. This kind of utilization of unintentional stone knapping might have been the first step toward Oldwan-type hominid lithic technology.
My experience in the field, in return, had a strong influence upon my laboratory studies. I became sensitive to the environmental enrichment of captive chimpanzees. We built 15-metre high climbing frames in our outdoor compound at KUPRI, planted trees, and introduced a small stream. I also learned the importance of the mother–infant bond among wild chimpanzees. This led us to ‘participation observation’ studies in the laboratory, in which we tested the cognitive development of infant chimpanzees raised by their biological mothers. This research method represents a clear contrast to previous research in captivity, where infants were often isolated from their mothers and were instead being reared by humans.
What is your most important finding in recent years?
We published an article on chimpanzee memory in December 2007 in Current Biology, reporting that the working memory of young chimpanzees is better than that of human adults. The task was to memorize Arabic numerals and their positions, briefly presented on a computer monitor. Visit YouTube and search for ‘chimpanzee memory’ — you will find many of our video clips and see that the chimpanzees' performance is truly astonishing!
What is the significance of your finding?
This is the clearest evidence that chimpanzees can outperform humans in a cognitive task. Many people still hold a kind of naïve belief that humans are superior to nonhuman animals in all intellectual domains. This is not true. Each species has developed its own unique way of adapting to the environment. It is time to say farewell to the human–animal dichotomy. Humans are a species within the animal kingdom. The study of the chimpanzee mind might provide a good bridge connecting humans to the rest of the organisms with whom we share this planet.
What would you like to do in future?
I have learned a lot from chimpanzees. I feel that it is now my turn to work for them. Over the years, I have come to realise that the laboratory study of nonhuman animals should be accompanied by considerations of animal welfare, while field studies should go hand in hand with wildlife conservation. We are facing problems both in Japan and in Africa. There are 348 chimpanzees in Japan at present. Among them, 72 are ex-biomedical research subjects. At the end of 2006, a collaborative effort completely put a stop to the use of chimpanzees for invasive biomedical research in Japan. While this is good news, it also means that we must now find a way to continue caring for these chimpanzees. To solve the problem, we created the first chimpanzee sanctuary in Japan. We also founded the Wildlife Research Center of Kyoto University in 2008 to look after the endangered species, including the sanctuary chimpanzees, in collaboration with zoos and aquariums.
In Africa, the size of the Bossou chimpanzee community has dropped to 13 individuals following a flu-like epidemic in 2003. We have already started the ‘Green corridor’ project — a scheme of planting trees in the savanna that separates the Bossou community from the neighboring communities of Mont Nimba, a World Natural Heritage site. Mont Nimba itself is facing a serious threat from iron ore mining. Throughout Africa, chimpanzee lives are being threatened by deforestation, poaching and bush-meat trade, and contagious disease: all direct results of human activity. It is not easy to find the ultimate solution for a harmonious coexistence between humans and other organisms. I want to keep things simple — to make my own efforts based on my place in the world. Step by step, every single day can make a change