Tag Archives: Washoe

Animal seminar at Tel Aviv University

On Monday 16th of June 2014 the seminar Animal behaviour, cognition & welfare will be held in Tel Aviv, Israel. The 1-day seminar is organised by AnimalConcepts in collaboration with the Institute for Animals in Philosophy and Science and is hosted by Tel Aviv University.

How much do we really know about animal minds? How can we use the tools of science to investigate what is happening in the minds of beings that, with just a handful of exceptions, are incapable of telling us? And perhaps most importantly, how can we use our knowledge of what animals are thinking and feeling in order to improve their lives? Join us for this one day seminar where we explore the modern science of animal behaviour and cognition, and discuss how it is being used to inform policy and practices to improve the welfare of the animals in our care, as well as in the wild.

Israel flyer 2014

Psychologist and philosopher dr. Esteban Rivas will give three lectures about the following subjects: animal cognition, animal language and communication, and animal ethics. Psychologist Sabrina Brando, owner of AnimalConcepts, will talk about captive wildlife research as an enrichment tool. Primatologist and animal behavior and welfare specialist dr. Ori Pomerantz will give a lecture entitled: “Employing cognitive-bias paradigms for the assessment of the animals’ welfare state. For the provisional program click here.

The seminar will be held in English and will take place at the Department of Zoology of Tel Aviv University, Israel. The registration fee is 45 euro and the student fee is 35 euro. For more information and how to register go to the website of AnimalConcepts.

Looking forward to meeting you in Tel Aviv!


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Filed under Animal Cognition, Animal Communication, Animal Ethics, Language research with animals, Lectures and courses

Animal Lectures in Amsterdam

After getting multiple requests for lectures in English, dr. Rivas has decided to organize four English lectures about animals. They will be given on a Saturday afternoon, from 12.30 to 16.30 hours and will be held at the Free University in Amsterdam.

Saturday 11 January:

Animal Lecture 1: Consciousness and emotions in animals.


Do animals dream?

Do animals dream?

During this lectureday dr. Rivas will address the question whether other animals have the ability to experience things like pain and pleasure. Are animals robots without subjective experiences or do animals experience sensations and other things in a phenomenally conscious way? The French philosopher René Descartes claimed that nonhuman animals could not be conscious. Behaviorism in psychology also led to a taboo on the subject of consciousness in general. Even today there are still scholars who do not ascribe consciousness to animals, often based on the absence of ‘higher’ cognitive abilities and language. In contrast are positions that argue for the presence of consciousness in animals by argueing from analogy, using systematic analyses of the nervous systems and behaviours of animals. Rivas will present the work of Jaak Panksepp on affective neuroscience, which shows that at least all mammals, and birds too, share a number of brain centers for the same emotional systems. I will also discuss the various emotions of animals. Which particular emotions do they have? Pleasure, pain, jealousy, guilt, gratitude? Which animals seem to mourn deceased conspecifics? And what similarities exist between humans and other animals with regard to altered states of consciousness, such as dreaming and being under the influence of psychoactive medication and drugs?

Saturday 29 March:

Animal Lecture 2: Communication and language research with animals.


The chimpanzee Tatu makes the sign for BLACK.

The chimpanzee Tatu makes the sign for BLACK.

Animal communication takes places in many different ways. At a certain moment in evolution animal communication developed into human language. The question that scientists and philosophers have had for a long time, is whether humans are the only animals with language. In this lecture dr. Rivas will present recent developments in the scientific study of animal communication and he will discuss the results of language research with nonhuman animals. The following subjects will be presented: The characteristics of human language and animal communication. The relationship between language and brain and language development in human children. What referential information about predators is transmitted in the alarm calls of vervet monkeys and prairie dogs? What are the similarities between birdsong and human language? The natural communication of great apes: facial expressions, vocalisations and gestures. Language research with great apes has been taking place for more than a century. First there were attempts to teach them words, after which several projects were successful in teaching signs to great apes. The famous chimpanzee Washoe and the gorilla Koko learned to use more than hundred signs to communicate with humans. The bonobo Kanzi and other apes learned to communicate by means of geometric symbols or lexigrams. But there is also an ape language controversy, because in what way does this use of symbols compare to human language? Dr. Rivas will also present his own study of the language apes. Finally, the results of language research with dolphins, sealions, parrots (the famous parrot Alex), and dogs will be presented.

Saturday 5 April:

Animal Lecture 3: Recent research on the intelligence of dogs.


How smart are dogs?

How smart are dogs?

In the past 19 years many new and exciting studies have been carried out on the intelligence or cognition of dogs. Special institutes for intelligence research with dogs have been set up at universities all over the world: the Family Dog Project at the University of Budapest (Adam Miklosi), the department of Comparative and Developmental Psychology at the Max Planck Institute for Evolutionary Anthroplogy at the University of Leipzig (Juliane Kaminski and Michael Tomasello), the Clever Dog Lab at the University of Vienna (Ludwig Huber), and the Duke Canine Cognition Center at Duke University in the USA (Brian Hare). During this lecture dr. Rivas will present and discuss the results of all these recent studies with dogs. Central themes are the social and physical intelligence of dogs. Subjects that will be presented are, amongst others: Do dogs understand what humans see, hear or know? What do dogs learn by social observation, is there evidence for imitation in dogs? Do dogs understand human communicative signals, such as pointing and gaze direction? How much evidence exists regarding empathy in dogs? What are the results of language research with dogs? Are dogs able to understand human words? What does dogs’ physical intelligence consists of, what do they know about their physical environment? Are dogs aware that objects keep existing (object permanence), can dogs count? How do they behave in exciting studies such as the magic cup? This lecture will give you a good review of the current state of affairs of our scientific knowledge about the intelligence of dogs. This will probably change your own view of what dogs are capable of in terms of intelligence.

Saturday  12 April:

Animal Lecture 4: Introduction to animal ethics.


How should we relate to other animals?

How should we relate to other animals?

On this lectureday I will give a review of the most important schools of thought in animal ethics. After a short introduction to philosophy and ethics and the history of moral thought about nonhuman animals, the most important current philosophers will be presented: Peter Singer and his utilitarian ethics of animal liberation. Tom Regan, who argues for animal rights from a deontological perspective. Philosophers who argue that the presence of sentience or consciousness is sufficient condition for moral consideration, such as Gary Francione. Philosophers who make a moral distinction between humans and other animals based on the capacity for language (Frey, Carruthers). Feminist animal ethics which looks at animals with the concepts of care and dialogue. And finally, deep ecology, in which humans and other animals are part of the biosphere. Questions that will be discussed are, a.o.: Is having self-consciousness of importance for the way in which an animal should be treated? Are some animals replaceable? When is a position speciesism, discrimination based on species? What are the arguments for equality among all animals? Do all living beings have an inherent value? What should one do if one were in a lifeboat with 3 other humans and 1 dog, and one individual should be thrown overboard in order for the lifeboat not to sink?

Practical information. The Animal Lectures are organized for people who work with animals professionally, for students, and for anyone interested in animals and eager to broaden their knowledge about them. A specific former education is not required. The lectures start at 12.30 and end at 16.30 hours. Registration for the Animal Lectures costs 35 euro for each lecture. Students with a student ID card pay 25 euro for each lecture.

Location: Main Building of the Free University, De Boelelaan 1105, Amsterdam. This location is well accessible both by car and public transport. Free parking is possible at the Gustav Mahlerlaan and the A.J. Ernstlaan.

Registration: You can register by simply sending an email message to estebanyes@gmail.com. You can register for all or several of the lectures. You will then receive an email message with all practical details, such as payment etc.

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Filed under Animal Cognition, Animal Communication, Animal Consciousness, Animal Emotions, Animal Ethics, Language research with animals, Lectures and courses

“Communication and language in animals” course for everyone

In the past few years I have given with great success the course “Communication and language in animals. Recent developments in scientific research” at various universities in The Netherlands for the Higher Education for Older People (HOVO), in which I discuss the current scientific state of affairs with regard to the natural communication of all kinds of animals and the results from language research with various animals. At the HOVOs this course was only available for people of 50 years and older. I repeatedly got requests to organize this course also for people younger than 50 and now it’s time to do so. The Institute for Animals in Philosophy and Science is organizing this November a 3-day course “Communication and language in animals” for people of all ages.


The horse Clever Hans, early 20th century Berlin. Hans purportedly could answer many human questions...

The horse Clever Hans, early 20th century Berlin. Hans purportedly could answer many human questions…

Birds sing, dogs bark, and humans talk: everywhere animals are communicating. In the animal kingdom communication takes place in all kinds of ways. At a certain moment in evolution animal communication developed into human language. The question that scientists and philosophers have been asking for generations, is whether humans have a lonely position as the only animals with language. From the beginning of the 20th century many studies have been carried out in which scientists tried to teach all kinds of nonhuman animals (parts of) the human language. Science has also made a lot of progress in the study of the natural communicaton of animals. In this course we will discuss the current state of affairs with regard to research on communication and language in animals. The course will give you a broad overview, in which the communication and language research with nonhuman animals is presented in a critical manner.

Day 1. Saturday 2 November: Communication and human language: Characteristics and definitions. Language development in human children. The alarm calls of vervet monkeys and prairie dogs. The communication and dances of honeybees. The communication of whales and dolphins.

What information about predators do these prairie dogs communicate to each other?

What information about predators do these prairie dogs communicate to each other?

On the first day we will discuss the various kinds of communication that exist. In order to make a proper distinction between animal communication and human language, the characteristics of human language are presented. We discuss the relationship between language and brain and we will look at language acquisition in human children. We will also look at the interpretation of animal communication: only an expression of passions and emotions, or can animals also refer to various things in the outside world? What meaning can be found in the alarm calls of vervet monkeys and prairie dogs? We will also discuss the dances of honeybees, with which bees can transmit information about food locations. Finally, the natural communication of whales and dolphins is presented, including whale song.

Day 2. Saturday 9 November: The natural communication of, and language research with, the great apes: chimpanzees, bonobos, gorillas and orangutans.

The chimpanzee Tatu makes the sign for BLACK.

The chimpanzee Tatu makes the sign for BLACK.

How do our closest relatives communicate? In the past few decades our knowledge has increased about the various forms of communication of the great apes. We will discuss the communicative nature of the facial expressions of great apes, their particular vocalizations, and the communicative gestures that great apes naturally use. Next, the language research with great apes is presented. For more than a century, scientists have attempted to teach a human language to great apes in all kinds of, often controversial, studies. Chimpanzees and other apes were used in experiments in order to make them pronounce human spoken words. Later, chimpanzees, gorillas and orangutans were taught signs with which to communicate with humans. Famous apes like the chimpanzee Washoe and the gorilla Koko learned over a hundred signs. Nevertheless, soon the ape language controversy started, because in what way can we talk about actual language in these apes? We will discuss the methodological pitfalls and mistakes in interpretations and conclusions. I will also present my own study of the apes in language research. Finally, we will also discuss the research with Kanzi and other bonobos who learned to communicate by using geometric symbols (lexigrams).

Day 3. Saturday 16 November: Bird song and bird calls. Language research with dolphins, sealions and parrots. Understanding of human communicative signals by dogs and other domesticated animals. Language research with dogs. Evolution of human language.

Songbirds sing songs, but also have all kinds of calls with which they communicate.

Songbirds sing songs, but also have all kinds of calls with which they communicate.

All bird species have various kinds of calls: to remain in contact with each other, to express emotions, to warn for predators. How do you recognize these calls when you hear them in your garden or outside? Besides using calls, songbirds, parrots and hummingbirds also sing songs with a specific structure and function, which they learn from their parents. What are the similarities between birdsong and human language? Next, we will discuss language research with other animals than apes: Can dolphins and sealions carry out commands that are given by humans in the form of signs? Can parrots communicate with humans by speaking human words? And what do dogs and other domesticated animals understand of our communication, like pointing and gaze direction? Recent studies have shown that some dogs can understand hundreds of human words for all kinds of objects. Finally, we will discuss several theories about the evolution of human language.

After this course you will have a fresh, new look on the ways in which animals communicate and you will have knowledge regarding the question in what way we can talk about language in other animals. Besides surprising information about the animals around us you will also get an impression of the controversies in this field of study.

For whom? The course is meant for people who work with animals professionally, for students, and for anyone interested in animals and eager to broaden their knowledge about them. A specific former education is not required. The course will be given in the Dutch language, but a passive knowledge of English is convenient, given that some of the films that I will show are not subtitled.

Practical information. The course will be given on three Saturdays in November: November 2, 9 and 16. Each day will start at 11 o’clock in the morning and will end at half past 5 in the afternoon. It is recommended that one takes the whole course of three days, but one can also register for 1 or 2 days of the course. The registration fee is 160 euros for the whole course (students with student ID card 100 euros), or 60 euros (40 euros for students) for each separate day. The price includes a (vegan) lunch and coffee and tea.

LocationMadame de Pompadour, Langsom 28 in Amsterdam. This location is very well accessible both by car (there is even free parking!) and by public transport.

You can register by sending a message to estebanyes@gmail.com or by filling out the form below: 

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The Minding Animals Conference

From 4 to 6 July the second Minding Animals Conference was organized at Utrecht University. Every three years this conference is held in another university city, set up by Minding Animals International. The purpose of these conferences is to build bridges and bring people together from science, philosophy and animal organizations. During the conference many lectures are given about all kinds of subjects that have to do with animals: the intelligence or cognition of animals, emotions and consciousness of animals, animal ethics, politics and policies regarding animals, animals in literature and art, and yet more subjects. Hundreds of people from all over the world had travelled to Utrecht for this 3-day conference. The programme was packed and started each day at 9 in the morning, to end only at 10:30 in the evening. It was a tiring but very interesting conference.

Christian democrat minister of agriculture Henk Bleker opened the conference with a long self-apology about his farming background, assuring all present that farmers also have a good relationship with their animals.

My two lectures were scheduled for the first day, Wednesday July 4. In the morning during the session “Animal capacities: concepts, beliefs and language” I gave my lecture Have nonhuman great apes acquired human language? In this lecture I gave a review of all language research with nonhuman great apes that has been carried out for over a century now. I discussed the results of these studies in which great apes were taught some form of human language, by spoken language experiments, sign language projects and communication by geometric symbols or lexigrams. Below you will find the text of both lectures. The conclusion of my lecture was that chimpanzees, bonobos, gorillas and orangutans are able to learn individual symbols for all kinds of objects and actions, but that nonhuman great apes do not combine these symbols in a meaningful, structured way and that they have a limited motivation for using these symbols: in order to obtain things and actions from humans. For this reason I ended the lecture with the position that nonhuman great apes have not acquired a human language and that the capacity for language is a qualitative difference between humans and other apes. In general the lecture was received well. However, some people were not pleased by my conclusion. The fact that I don’t ascribe language to other animals amounts to some people to confirming or creating anew a dichotomy between humans and other animals. Unfortunately, people then don’t listen good enough anymore to the scientific arguments that I presented.

In the afternoon I gave my second lecture during the session “Animal ethics: capacities and relations.” This lecture was called Is absence of language in nonhuman great apes morally relevant? and was the moral sequel to the scientific conclusions that I had presented in the morning. In the lecture I criticized the positions of philosophers such as R.G. Frey and Peter Carruthers, who take the capacity for language as an important moral distinction between humans and other animals. I gave my criticisms of their arguments and came to the conclusion that the capacity for sentience (the ability to experience pain and pleasure) or phenomenal consciousness (the experiential aspects of our mental states) is a sufficient condition for a moral equality among all animals. In my view the presence or absence of language does not lead to a morally different treatment of humans and other animals, and I argue for equality of all animals, with or without language. Again the lecture was visited well, among the audience the famous philosopher Peter Singer. The reactions were very positive, people thought it was a good discussion of the language issue. Some people came to me afterwards and said they thought it remarkable that I argue for cognitive or motivational differences between humans and other animals (no language), and yet that I argue at the same time for a completely egalitarian relationship between all animals. They thought I was a pleasant exception in that, which, sadly enough, is indeed the case.

Below you will find the text of both lectures. Let me know your opinion about them.

Have nonhuman great apes acquired a human language? 

Before I could start the chairman of the session and me had to solve some computer problems.

When psychology and linguistics started to develop as scientific disciplines in the 19th and 20th century, a scientific oddyssey was embarked upon to discover whether nonhuman great apes could acquire something of our human language. Though several scientific questions laid at the base of this oddyssey, such as the question how much of behaviour is innate or acquired by learning, a major motivation for these studies has also been plain scientific curiosity: how far can our closest furry cousins go in acquiring parts of the human language when we teach them this?

Chimpanzees, bonobos, gorillas and orangutans have been used in all kinds of language studies for almost a century now, starting in 1909 with the American psychologist Lightner Witmer and the chimpanzee Peter. Later this type of research with nonhuman great apes has been called Ape Language Research or ALR. In this lecture I will present the results of this century of ape language research and I will answer the question whether nonhuman great apes have acquired a human language.

Before I continue, let me give you the definition of language that I use. Language, in my opinion, consists of three main characteristics. First, the use of words or signs as symbols, referring to things in the outside world or to abstract concepts. Second, the ability to meaningfully combine these symbols by means of grammar and syntax. Third, a rich variety of functions. The functions of human language can be summarized as follows: the transmission of information, expressing one’s thoughts and emotions, the regulation of social relationships, clarification of ideas, humour and play with language, lying, referring to things displaced in space and time and the telling of stories, fantasies and all kinds of abstract concepts. Language gives us the ability to express all these functions in a very detailed and specific way. Indeed, this conference itself is a good example of the possibilities of human language.

When scientists first tried to teach language to nonhuman great apes, only spoken language was considered to be a real human language. The first ape language experiments were thus focused on teaching apes to speak words, starting in 1909 with Lightner Witmer from the University of Pennsylvania, who tried to teach the 5-year old chimpanzee Peter to speak the word mama and the letter p. Later other scientists followed with their own chimpanzees and also orangutans. Usually they tried to make the ape speak a word by manipulating the mouth and lips of the ape subjects. Often the apes were living in the human homes of the scientists, where they were sometimes cross-fostered, or raised by humans as if the ape was a human child. The spoken language experiments were quite unsuccesful, however, the biggest achievement coming from the chimpanzee Viki, who lived with Keith & Catherine Hayes from 1947 to 1953. After these 6 years of training, Viki was able to produce mama, papa, cup and up. However, Viki had a lot of trouble producing these words, which were often inaudible, and more importantly, used in the wrong contexts. The failure of the spoken language experiments was explained by the differences in vocal apparatus between human and nonhuman apes: the nonhuman apes were physically unable to produce actual human words.

In the 1960s new research on human sign language showed that signed languages are just as complex and rich as spoken languages, elevating sign language from its originally prejudiced position as not a real language. This change in perception of human language caused a new chapter in ape language research: now it was the question whether nonhuman great apes could learn and acquire signs. In 1966, the psychologists Allen and Beatrix Gardner from the University of Nevada at Reno started with Project Washoe, in which they taught signs to the wild-caught chimpanzee, Washoe, who was about 10 months old when the project started. Cross-fostered by the Gardners, she was immersed in a linguistic environment in which the humans communicated by using signs. Moulding the hands of the chimpanzee into the right configuration for a sign turned out to be the most succesful method by which to teach signs. After almost 4 years the Gardners had made a historic achievement: Washoe had acquired about 132 signs for various objects and actions. This success with Washoe inspired further projects with other apes. The Gardners and later Roger and Deborah Fouts taught signs to 4 more, newborn, chimpanzees and according to the Fouts the adopted son of Washoe, Loulis, learned signs from the other chimpanzees, sometimes even by active teaching from Washoe. In 1972, the psychologist Francine Patterson of Stanford Univeristy started Project Koko, in which she taught signs to the gorilla Koko, and later to her male companion the gorilla Michael. In 1978, lastly, the anthropologist Lyn Miles from the University of Tennessee at Chattanooga started Project Chantek, with the orangutan Chantek.

Besides projects in which apes were taught sign language, since the 1970s other projects were set up in which apes were taught symbols in the form of lexigrams, geometric, often arbitrary symbols, on a plastic board or computer screen. Duane Rumbaugh started in 1971 with Project Lana, in which he taught the chimpanzee Lana lexigrams for objects. Later, with his wife Sue Savage-Rumbaugh, the chimpanzees Sherman and Austin were taught lexigrams for all kinds of objects and actions. In the 1980s work by the Rumbaughs started with bonobos, their star subject being the bonobo Kanzi, who eventually learned to use hundreds of lexigrams.

The scientists of these sign language and lexigram studies with nonhuman great apes eventually claimed that their ape subjects had acquired (some form of) human language. Not only had the apes learned that a symbol can refer to something in the outside world, the capacity for reference, but the apes also made meaningful combinations of symbols, even expressing grammar in these combinations, mostly by use of a specific syntactical order of combining symbols. Furthermore, it was claimed that the apes used the symbols for a rich variety of functions, not only requesting objects or food from their human caretakers, but also commenting on the things they saw, and even expressing their emotions and thoughts through their use of symbols. For example, the Fouts claimed that Washoe could use the sign HURT to express that she had a stomach ache. Especially Patterson has claimed that the gorilla Koko expressed her feelings a lot, such as signing HAPPY GOOD YOU COME when visitors arrived, and signing CRY and SAD when her famous kitten All Ball died. The Fouts and Patterson also claimed that the apes used signs such as DIRTY and DEVIL to make insults, for example, when Washoe was denied something by Roger Fouts, she signed DIRTY ROGER.

Meanwhile, another project with a signing chimpanzee was carried out in the 1970s. This was the project by the psychologist Herbert Terrace, who at Columbia University taught signs to the chimpanzee Nim Chimpsky, named after the famous linguist Noam Chomsky. Terrace obtained quite different results than the other researchers and he concluded that the apes had nót learned a human language. The publication of his work caused a lot of upheaval, in what has become known as the ape language controversy.

This controversy drew attention to problems of methodology and interpretation in ape language research. Terrace was the first to carry out systematic video analyses of the sign interactions between the chimpanzee Nim and the humans. To his surprise he found that Nim imitated the signs the humans made to a large extent. Combinations of signs appeared not to show any semantic or syntactic structure, consisting largely of stringing signs together in order to get the human into action. Motivationally, Terrace concluded that signing apes only used their signs acquisitively: in order to acquire objects and actions or attention from the humans, thus using the symbols in a very limited way compared to what human children do when they first start acquiring language, who also ask questions, describe thoughts and express emotions.

What are we to think of this whole controversy, which persists up to this day, with more or less two camps still criticizing each other: those who believe that nonhuman apes have acquired a human language, and those who do not. Who is right?

When I studied psychology I became very intrigued by the field of ape language research. I was less interested in the question whether the apes had acquired an actual language. My interest was more in the possibility that this form of symbolic communication could be a new and third way to obtain new knowledge about the consciousness or inner nature of the apes: their thoughts and emotions. Scientists already analyzed the nervous systems and nonverbal behaviour of animals in their study of animal consciousness, but the ape language studies promised a verbal and direct expression of their inner conscious states. During my psychology studies I visited the Chimpanzee and Human Communication Institute of Central Washington University, where the Fouts continued to study the sign use of Washoe and four other chimpanzees. I also visited the other ape language researchers and returned to Holland, determined to set up a Ph.D. project about the possibly linguistic apes. Working from the philosophy of science section at the Philosophy Department of the University of Nijmegen, I paid multiple visits to the States in the 1990s to collect data about the apes in the language projects.

My first focus was on the use of what in child language research are called internal state terms: words or signs that refer to Positive affect, such as happy, love and funny, Negative effect, such as angry, cry, sad, Physiological states, such as hungry, thirsty and tired, Perception: see, hear, smell, pain, cold and Cognition: know, think, remember. Human children start acquiring internal state terms when they are 2 years old and start using these for other people when they are 2.5 years old. According to the Fouts, the signing chimpanzees had acquired signs that referred to the chimpanzees’ internal states, such as HAPPY, SAD and CRY. However, when I investigated the archives of the signing chimpanzees from 1970 to 1995, I found that almost all of these signs had not been used at all in these 25 years. The signs that they did use could all be explained as not referring to their inner states, but as useful signs to manipulate the humans. The use of CRY, for example, was mostly used by the chimpanzees after they had first made a request for food or an object, which was then denied by the humans, to which they then signed CRY. When I visited Koko and Penny Patterson at the Gorilla Foundation in California, I was given access to all the Koko diaries on microfilm from the beginning of the project to 1995. The discovery I made there, was that Patterson had been unacceptably selective in her presentation and publication of Koko’s sign use. The unedited Koko diaries showed that Koko was drilled in using signs such as SMILE and CRY by showing her pictures of smiling and crying humans many times a day. More importantly, this unedited material also showed the many, many times that Koko used these signs incorrectly. Thus she would sign CRY to a picture of a smiling man and SAD CRY DEVIL to a picture of a horse. Patterson then gave an unrepresentative presentation of Koko’s signing by only publishing her sign utterances that appeared to be linguistic or referring to internal states, while omitting all other clearly nonlinguistic use of signs by Koko. These discoveries made me abandon this focus on possibly internal state signs, because these were either not used by the apes or did not show an actual reference to inner states.

I then changed my study into a large, systematic analysis of all use of signs by Washoe and the other chimpanzees at the Chimpanzee and Human Communication Institute, when they were in interaction with longtime human companions. I hoped to find solid data that could show what the chimpanzees were actually doing with the signs and whether their sign use showed any linguistic properties. I analyzed in great detail 22 hours of videotaped interactions from 1992 to 1999. The subjects of my study were Washoe, who was then between 26 and 34 years old, Moja, who was 19 to 26 years, Tatu, between 16 and 23 years, Dar, 15 and 23 years, and lastly, Loulis, Washoe’s adopted son, who was then between 14 and 21 years old.  3,500 chimpanzee sign utterances were obtained for analysis. I determined the particular individual signs that the chimpanzees used, the kinds of combinations of signs that they made, and each sign utterance was coded for its communicative intention or the reason for which the chimpanzee used the utterance.

These were my results: The individual signs that Washoe and the other chimpanzees used mostly consisted of object or action signs, with the signs DRINK, FLOWER, EAT and GUM among the most used signs. Their combinations of signs showed no semantic or syntactic structure and the longer combinations were quite similar to Nim’s: stringing signs structurelessly together, in order to provoke the humans into giving them something. For example, Washoe made the following 13-sign utterance: DRINK HOT GIMME DRINK TOOTHBRUSH GUM HOT GIMME TOOTHBRUSH GIMME TOOTHBRUSH GUM BOOK. In terms of their communicative intentions, the chimpanzees predominantly used signs when they wanted to request objects or actions from the humans. Thus, Terrace’s characterization of ape sign use as acquisitive, used to acquire things from humans, was very appropriate for Washoe’s and the other chimpanzees’ use of signs. For this reason I gave my dissertation the title GIMME GIMME GIMME. The results that I obtained were remarkable findings. They demonstrated a nonlinguistic use of signs of the same apes of which it had been claimed for decades that they signed linguistically.

A further result that I’d like to mention specifically is the use of signs by Loulis, Washoe’s adopted son.  The Fouts had claimed that Loulis had learned over 50 signs from the other chimpanzees (because the humans did not sign in his presence for more than 5 years), which was  then interpreted as a cultural transmission of a human language by chimpanzees. In the videotaped interactions that I analyzed Loulis only used the four signs POINT, GIMME, CHASE AND HURRY. These last three signs are normal chimpanzee gestures that have been observed in many chimpanzees in captivity and in the wild. GIMME is the begging gesture with a stretched hand palm up, CHASE the wrist-hit gesture to initiate play and HURRY the impatience gesture of shaking the hands. Thus Loulis had only learned to point to things that he wanted. He never used a sign to refer to objects and did not show a linguistic use of signs.

The different results that I obtained with Washoe and the other chimpanzees, compared to the earlier studies, can be explained by differences in methodology and interpretation. In my study I only used videotaped interactions and I used large corpora or collections of unedited sign use by the chimpanzees. These methods had not been used enough in the previous studies. Many claims from the ape language researchers had been based on unfilmed and unrepresentative instances of signing by the apes, causing unwarranted linguistic conclusions.

Let me explain this in more detail. The problems of using unfilmed data are that these are insufficiently reliable. First, perception errors can occur, mistaking a scratch for a sign or mistaking one sign for another. For example, the signs HURT and BANANA are close to each other. HURT is made by contacting the tips of extended indexes of opposite hands. BANANA is made by the index grasping or rubbing the tip of the other hand’s extended index and pulling it toward oneself. (of ene sign voor andere). A human, focused on finding evidence of linguistic sign use, as all researchers were in these projects, could then mistake Tatu signing TATU BANANA for TATU HURT. Second, memory errors can take place in the time it takes after a signing interaction with an ape to then go back inside and write down the observation. A human might then forget all the exact individual signs that Washoe had made or the correct sequence of the signs. For example, Washoe could have signed BOOK HURRY APPLE ORANGE GIMME RED GIMME YOU WASHOE. An hour or so later the human could remember only something like HURRY YOU GIMME RED APPLE. Third, with unfilmed observations there is no way of assessing the role of imitation of the human by the apes, as there is no reliable information whatsoever on what the humans signed in these interactions.

The fact that large unedited corpora of sign use were used insufficiently means that the human researchers in these projects focused on incidental sign use that appeared to be linguistic, when only by a thorough and systematic analysis of all sign use can one make definitive conclusions. For example, Washoe’s description of a swimming swan as a WATER BIRD has often been presented as an example of a meaningful and creative combination of signs. However, without the analysis of large corpora there is no way of knowing whether Washoe may also have made many unmeaningful combinations of signs such as WATER BANANA and COOKIE BIRD. In which case the WATER BIRD combination would have been just another meaningless combining of signs. When I analyzed the unedited Koko diaries on possible internal state terms this was exactly what I found: Patterson had published only those sign instances of SAD and CRY in which she seemingly referred to her emotions and thoughts, but systematic analysis of all Koko’s sign use showed that she more often used such signs without any reference to her emotions.

         Problems of interpretation have also been part and parcel of the ape sign language projects. For example, much has been made by the Gardners and Fouts of the fact that the chimpanzees asked questions, asking for information, using the same accompanying nonverbal behaviours in which humans ask a question in sign language: holding the sign, looking at the other person while waiting for an answer. However, these accompanying behaviours are evidence of intentional communication rather than demonstrating a linguistic use of signs. More importantly, all of the instances in which the apes asked a question can better be interpreted as the apes asking or making a request for food, objects or actions and then waiting for the human to give the ape something. Another example is the interpretation of the sign DIRTY as an insult. DIRTY is made by loudly hitting the chin with a hand, thus making a loud noise by which to attract the attention of a human. DIRTY is then better interpreted as an attention-getter. Chimpanzees in captivity all over the world use many such attention-getting behaviours to draw the attention of their human caretakers.

Besides Terrace’s analyses and my own study, only one further study in ape language research exists that is methodologically and scientifically sound. This is the study published in 1993 by Sue Savage-Rumbaugh of Kanzi. Not of his use of lexigrams, but of his understanding of short English commands, such as “put the carrot in the water” or “put the keys in the refrigerator”. All interactions were filmed and the contents published entirely. The results showed that Kanzi was indeed able to understand hundreds of human words for objects and actions.

So, after almost a century of ape language research what conclusions can we draw today about the capacity for language in nonhuman great apes? Again, in the definition of human language that I use, language consists of 3 important aspects: 1. The use of symbols, 2. The capacity to meaningfully combine these symbols grammatically and syntactically, and 3. A rich variety of functions for which the symbols are used. Using this definition of language I reach the following conclusions: Nonhuman great apes are able to understand hundreds of symbols for all kinds of objects and actions. Something which has also recently been found to be true for border collie dogs, such as the German border collie Rico, who understands over 200 words for toy objects and the American border collie Chaser who was demonstrated to understand even over a thousand words for objects. So the apes can understand symbols. But when the apes combine symbols, however, these combinations don’t show any semantic or grammatical structure. Lastly, the apes almost only use their symbols to acquire things from humans, whereas humans themselves, including human children who start acquiring language, use language for a rich variety of different functions. Thus, I conclude that nonhuman great apes have not been able to acquire language and I claim that this is a qualitative difference in capacities between human and nonhuman great apes. In my next lecture I will discuss what this conclusion means for our ethics towards nonhuman great apes.


Is absence of language in nonhuman great apes morally relevant?

The capacity for language has long been a major dividing point between humans and all other animals. For the 17th century philosopher René Descartes human language was the only certain proof that a being possessed not just a body, but also a mind. Descartes defined language not only as an ability to use words, which he knew parrots could also learn and use. He saw language particularly as the meaningful combination of words or symbols, through which humans can express thoughts and all their inner life. In contrast, in Descartes’ view, birds using words and all other animal communication simply consisted of a mindless expression of the animals’ passions or motivation. Indeed, his assumption that parrots who had learned words only used these to express their passions, was for Descartes a good argument that all nonhuman animals don’t even háve thoughts, a mental life or a mind. Nonhuman animals thus were reduced to mindless automata or machines. The dichotomy between mindful humans and mindless animals thus constructed by Descartes, had a major impact on the way science and philosophy viewed nonhuman animals for centuries. The absence of language in nonhuman animals has since often been used as an excuse for quite speciesist moral philosophies and has led to the justification of practices such as animal experimentation.

Since animal ethics came up in the 1970s as a subdiscipline of ethics, language has continued as a morally relevant ability in several animal ethics theories. I will mention two cases. The philosopher R.G. Frey from Bowling Green State University in Ohio argued that language is a required capacity in order to have beliefs and desires and therefore interests. He expressed this view in his 1980 book Interests and Rights: The case against animals and in his 1983 book Rights, killing and suffering. According to Frey, because nonhuman animals are incapable of having desires and therefore interests, they don’t have rights like humans do and he argued for an inegalitarian view between humans and other animals, where nonhuman animals are of lesser moral value than linguistic humans. The British philosopher Peter Carruthers, now at the University of Maryland, claimed that language is a necessary ability to experience mental states, argueing that nonlinguistic animals do not have sentience or phenomenal consciousness. Sentience was defined by Peter Singer in Animal Liberation as “the capacity to suffer and/or experience enjoyment.” Phenomenal consciousness is a term coined by the British philosopher Ned Block with which he refers to the experiential properties of sensations, feelings and perceptions, thoughts, desires and emotions. Carruthers published his view on animals in his 1992 book The Animals Issue and he has since continued to write further publications about it. In Carruthers’ view nonhuman animals, lacking language and therefore having no sentience, are not part of the moral community. Humans only have indirect obligations to other animals, such as not being cruel to them, because cruelty towards animals shows the presence of a cruel character, which could then also lead to cruelty towards other humans.

In the Great Ape Project (GAP), set up by Peter Singer and Paola Cavalieri, the results from the studies with signing apes were used in the argument for equality among all great apes (human and nonhuman). The project was launched in 1993 with the presentation of the book The Great Ape Project. Equality Beyond Humanity. Several ape sign language researchers contributed to this book with chapters in which they demonstrated the linguistic abilities of signing apes. These were Roger and Deborah Fouts, who worked with Washoe and four other signing chimpanzees,  Francine Patterson, who studied the signing gorillas Koko and Michael, and Lyn Miles, who worked with the signing orangutan Chantek. Later, Sue Savage-Rumbaugh, the researcher who studied the use of lexigram symbols by the bonobo Kanzi, joined this call for equality. In claiming that these nonhuman apes had acquired a human language, these researchers argued for an egalitarian treatment of nonhuman apes, similar to how we treat other human apes.

The participation of the ape language researchers in this moral project for equality has had severe negative consequences for one of the signing apes, something which I have been a personal witness to. When the GAP book was published, the signing orangutan Chantek was living at the field station of the Yerkes Regional Primate Research Center of Emory University, near Atlanta. The people in charge at the field station were not amused by Lyn Miles’ contribution to the project and frustrated her attempts to visit Chantek. Fearful of the implications of Chantek as a linguistic ape, Chantek was isolated alone in a cage and neglected. Caretakers were not allowed to sign to him, even though he signed to them about his wants and needs. All of this led to serious boredom in Chantek and in response he ballooned into a very fat orangutan. Linguistic apes were thus seen as a threat by the biomedical establishment, which feared that further experimentation on nonhuman great apes would become prohibited, as it has indeed become in various countries around the world, including the Netherlands, though sadly not (yet) the United States.

During one of the many coffee breaks.

As I talked about in my first presentation this morning, I have analyzed the archives of all the signing ape projects and carried out a systematic study of the use of signs by the famous signing chimpanzees. The results of these investigations were that there was no evidence for a linguistic capacity in these apes. If one considers all the results from the various ape language studies (including those that examine the use of lexigrams by bonobos such as Kanzi), one can conclude that nonhuman great apes are able to understand hundreds of words or signs. But when it comes to combining symbols in a meaningful or grammatical way there is no solid evidence that the ape subjects are able to do so. Also, when it comes to the motivation for (symbolic) communication it seems that there is a qualitative difference between human and nonhuman great apes. The apes in the language studies use symbols more as a tool to request things from humans rather than use it for a rich variety of motivations as humans do. Thus we can see a difference in motivaton for using symbols between human and nonhuman apes. The psychologist Michael Tomasello has suggested that this originates in the fact that nonhuman great apes are more focused on competition in their communication, while human apes are more focused on cooperation. So, until new evidence comes forth, we have to conclude that only human apes have the capacity for language and that this amounts to a qualitative difference between humans and other apes.

Where does this conclusion lead to, when it comes to our morality towards nonhuman great apes? Are nonlinguistic apes due less, morally, than apes who have language?

Let me take a closer look at the positions held by Frey and Carruthers. According to Frey, for a being to have interests, it needs to have desires. But a being can only have desires, if it has beliefs. And for the particular capacity to have beliefs, Frey argued that language is necessary. What are we to make of Frey’s position? Is it true that language is necessary in order for a being to have desires? Let’s specify the subject and focus on a being’s desire not to be in pain. Take a rat in a laboratory who is inflicted pain in an experiment. If I understand Frey correctly, the rat may feel pain, but cannot have a desire to be freed of this pain. However, when we look at the rat’s nonverbal behaviour we can see that she shows signs of being in distress and that she tries to get away from the pain. In another more personal example, a few months ago, we brought our cat to the vet to examine his blood. First he got an injection to make him doze off. However, immediately upon this injection our cat jumped of the vet’s table, ran away and tried to hide in the corner, hizzing aggressively at anyone getting close to him. Attempts to pick him up again were quite fruitless. Does this behaviour not show a desire to avoid pain? Indeed, in animal welfare research a lot of studies have taken place in which scientists look at particular preferences of animals. Famous are Marian Stamp Dawkins’ preference tests of various types of housing for chickens, which showed that chickens prefer soft floors over wire floors, as well as preferring floors with wood-shavings and such in order to be able to dustbathe and perform other natural behaviours. How would Frey explain these preferences? As something else than desires? But does not my cat have a desire to be out of pain and the chickens a desire to live in more accomodating spaces under more natural conditions? Clearly it is possible for a being to have a desire without having the capacity for language. This implies, then, that it is possible for non-linguistic beliefs to exist. Frey disagrees with that assumption by claiming that language is necessary in order to have a belief. This is because in his view you cannot have beliefs, if you can’t distinguish between true and false beliefs, and to be able to do that, you need language. I do not see why, when we look at the past decades of animal cognition research where many nonlinguistic cognitive abilities have been demonstrated in all kinds of animals. This includes the capacity to form beliefs about the physical and social world that surround an animal. In the example of my cat, my cat must have had some form of belief that the vet was only out to hurt him rather than help him, judging us as nasty beings he had to get away from. Frey’s position seems close to the flawed hypothesis of several philosophers of language that language is necessary for thought. This view has long been considered to be incorrect, partly because of all the evidence for cognitive capacities in nonhuman animals, but also because we now ascribe desires and beliefs to nonlinguistic humans such as pre-linguistic infants. In conclusion, then, Frey’s arguments do not hold.

What about Peter Carruther’s view? Frey still ascribed a capacity for sentience to nonhuman animals, while Carruthers claims that all nonlinguistic animals are not even sentient. He argues that a being can only experience something if the being can think and reflect about the various states the being is in. And in order to think and reflect, language is necessary. Again, like Frey, Carruthers links thought or cognition to language. So, again, we can rebut his proposal by showing that nonlinguistic cognition is possible and existing in many nonhuman animals. Indeed, language research with great apes and border collie dogs has shown that though nonhuman apes and dogs do not have language, they are capable of understanding hundreds of symbols and therefore have concepts of all kinds of objects and actions in the world around them.

However, different from Frey, Carruthers claims that language is not only necessary for thought, but also for sentience. He argues that it is the linguistic terms for various conscious states that make them phenomenally aware. Only by having the linguistic labels of pain and pleasure can we experience these states and can we even be aware that these states are different from each other. In Carruthers’ view nonverbal pain behaviour in an animal does not demonstrate sentience. He believes that any behaviour can exist without a mind or a sentient being who experiences these behaviours. He makes reference to being able to drive a car automatically while being absent-minded, and to the medical phenomenon of blindsight, a brain disorder where humans do not experience seeing things, but where further tests show that they nevertheless did perceive things. He even comes up with the purely hypothetical and speculative case of Penelope, a woman who shows abundant pain behaviour, screaming loudly and trying to get away, but without ever feeling or experiencing any pain. I believe that Carruthers has lost himself here in a hypothetical, unreal world. It is true that certain behaviours may occur mindlessly, as in certain reflexes or when we automatically carry out certain actions that we long ago learned. However, Carruthers is taking this fact too far in claiming that even pain behaviour can exist without feeling or experiencing pain. His hypothetical Penelope has never been found by scientists. Instead, all current knowledge shows that human and nonhuman animals react with similar nonverbal behaviours to pain and indeed we share the same pain centers in the brain such as the amygdala. These similarities in brain and behaviour demonstrate that nonhuman animals are just as able to experience pain as humans. Explaining the nonhuman animal behaviour differently risks the peril of not even being able to ascribe pain and other feelings to humans. In conclusion, then, Carruthers is wrong in claiming that language is necessary for sentience. The various phenomenally conscious or sentient states such as pain and pleasure existed before language and only we humans with language then add a linguistic label to these states.

The absence of language in nonhuman animals thus does not imply that they do not think, nor that they do not feel. Consequently, absence of language in nonhuman animals does not call for an ethics in which humans are treated differently from all other animals.

Arguing for equality among all great apes based on the capacity for language, like the Great Ape Project and the ape language researchers have done, however, is also incorrect, now that these new studies have shown that there is no evidence for the linguistic claims of these researchers. A qualitative difference between humans and other apes thus exists, in that only human apes have language.

It is, however, a matter of argument whether cognitive abilities such as language or rich motivations for communication are morally relevant at all or not. When we look at egalitarian morality towards humans, qualitative differences in cognition or motivation are usually considered to be irrelevant for a morally equal status of all humans. In what is known as the argument from marginal cases, humans with mental or physical disabilities are considered worthy of moral consideration just as much as supposedly ‘normal’ humans. This is because in egalitarian views on human morality, the presence of sentience or phenomenal consciousness in all humans is considered to be a sufficient condition for a morally equal status.

In order to avoid the risk of being speciesist by limiting equality to humans only, equality should be extended beyond humans to include all beings capable of sentience or phenomenal consciousness. Thus, equality for all great apes, nonhuman and human, is still arguable, despite the absence of language in our nonhuman cousins. Indeed, current scientific knowledge and opinion shows more and more evidence and arguments for the presence of sentience or phenomenal consciousness in all vertebrate animals and possibly also invertebrates. With sentience or phenomenal consciousness as a sufficient condition, equality should thus be extended to all nonhuman animals.

Before I finish, I would like to say something that is well apt for this conference, where building bridges between science and animal organisations is an important goal. I have found that animal lovers and activists often get very angry and accusative, when scientists claim that there are qualitative differences in cognition or motivation between humans and other animals. Like a red flag to a bull, any qualitative difference between humans and other animals is jumped at with attacks, condemning the messenger scientists as creating a new or confirming an existing moral dichotomy between humans and other animals. I think that this is a very unscientific and above all, very unhelpful way of dealing with the results of animal studies. Humans and other animals have similarities ánd differences and it is senseless to deny this. Just like cheetas are better in running than humans, so can humans be more adept in using symbols than other apes. I hope that the animal liberation and animal rights movements can adopt a truly scientific attitude and reconcile itself with the existing similarities ánd differences among all animals on this planet.

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My lectures at the Minding Animals Conference

From Wednesday July 4 to Friday July 6 the second Minding Animals Conference will be held in Utrecht, The Netherlands, hosted by the Ethics Institute and Faculty of Veterinary Science at Utrecht University. Recently the two abstracts that I submitted for two lectures at the conference were accepted. They will be presented during two of the parallel sessions. Below are these two abstracts.

The first lecture is part of the theme Animal Capacities, session 2b: Higher order cognitive capacities in animals.

Have nonhuman great apes acquired a human language?

Since the beginning of the 20th century scientists have been interested to find out whether nonhuman great apes can be taught some form of human language. The first studies tried to teach spoken words to great apes, but failed to do so. From 1966 onwards, the Gardners started projects using sign language, with the chimpanzee Washoe as their first subject. These chimpanzees acquired signs and other projects soon followed: Patterson studying the signing gorilla Koko and Miles analyzing the use of signs by the orangutan Chantek. Other researchers such as the Rumbaughs used geometric symbols called lexigrams, teaching them to bonobos such as Kanzi. Most of the ape language researchers concluded that a form of human language had been acquired by their ape subjects. However, another project with a signing chimpanzee, the one by Terrace with chimpanzee Nim, obtained results that did not point to a linguistic explanation of the signing behaviour. This caused what has become known as the ape language controversy. What can we conclude about language in nonhuman great apes after these decades of research?

The field of ape language research has suffered from problems of method and interpretation. Many studies did not film the interactions between the apes and the humans, leaving room for errors of perception and memory and making it unable to examine the role of imitation in the apes’ utterances. Selective presentation of data has also been a major problem. The author analyzed the archives of all the projects with signing apes and found that particularly Patterson presented the data about Koko selectively, publishing data that seemed linguistic, but omitting the rest of the data that showed otherwise. The author also carried out a large, systematic study of the use of signs by Washoe and the other signing chimpanzees, analyzing hours of videotaped interactions between the chimpanzees and their longtime human companions. The results were that the chimpanzees mostly made 1-sign utterances, using object and action signs and request markers. Combinations of signs showed no semantic or syntactic structure, but consisted largely of stringing various signs in order to provoke their human companion into action. The communicative intentions of the chimpanzees’ sign utterances predominantly consisted of requests for objects and actions. Another systematic study that filmed all the behaviour, was carried out with Kanzi, demonstrating that he could understand hundreds of English spoken words. Unfortunately, no further reliable studies have been carried out. If we take the scientifically sound studies into account, we can draw the following conclusion about language in nonhuman great apes. The apes have demonstrated understanding of human words or symbols (an ability that has recently also been demonstrated in border collie dogs). When it comes to combining symbols into meaningful utterances like humans do, however, the apes do something different. They do not add a meaningful structure to combinations, but string symbols together in order to manipulate the humans into fulfilling their requests. With regard to the motivation for using symbolic communication, humans have a rich variety of different motivations for communication. The nonhuman apes, however, almost exclusively use symbols in order to request objects and actions from the human. Terrace called this an “acquisitive” motivation. These conclusions mean that it has not been possible to teach a human language to a nonhuman great ape and that a qualitative difference remains between human and nonhuman apes. A difference that may not have moral consequences, however.

The second lecture will be part of the theme Animal Ethics, session 4a: The moral relevance of socio-cognitive abilities.

Is absence of language in nonhuman great apes morally relevant?

The capacity for language has figured as a morally relevant ability in multiple animal ethics theories. Frey argued that language is a required capacity in order to have beliefs and desires and therefore interests. Carruthers claimed that language is a necessary ability to phenomenally experience mental states, argueing that nonlinguistic animals do not have sentience. In the Great Ape Project (GAP), set up by Singer and Cavalieri, the results from the studies with signing apes were used as an argument for equality among all great apes (human and nonhuman).

The author analyzed the archives of all the signing ape projects and carried out a systematic study of the use of signs by the famous signing chimpanzees. The results of his study were that there was no evidence for a linguistic capacity in these apes. If one considers all the results from the various ape language studies (including those that examine the use of lexigrams by bonobos such as Kanzi), one can conclude that nonhuman great apes are able to understand hundreds of words or signs, but when it comes to combining symbols in a meaningful way (grammar) there is no solid evidence that the ape subjects are able to do so. Also, when it comes to the motivation for (symbolic) communication it seems that there is a qualitative difference between human and nonhuman great apes. The subjects of ape language studies use symbols more as a tool to acquire things from humans rather than use it for a rich variety of motivations as humans do. Tomasello has suggested that humans are more focused on cooperation, with nonhuman great apes focusing more on competition in their communication. Until new evidence comes forth, we have to conclude, then, that only human apes have the capacity for language.

Where does this conclusion lead to, when it comes to our morality towards nonhuman great apes? The position held by Frey and Carruthers is considered incorrect. It is not our linguistic terms for different conscious states that make them phenomenally aware, but the emotional feel of various conscious states has primacy, to which we humans then add a linguistic label. Arguing for equality among all great apes based on the capacity for language, like the GAP has done, however, is also incorrect, now that these new studies have shown that there is no evidence for the linguistic claims of the ape language researchers. Nonhuman great apes thus appear to be qualitatively different from human apes. It is, however, a matter of argument whether higher cognitive abilities such as language or rich motivations for communication are morally relevant or not. The author argues that in our morality towards humans we consider qualitative differences in cognition or motivation to be irrelevant for moral equality (cf. the argument from marginal cases). Among humans, the presence of sentience or phenomenal consciousness is considered a sufficient condition for a morally equal status. In order to avoid the risk of being speciesist by limiting equality to humans only, equality should be extended beyond humans to include all beings capable of sentience or phenomenal consciousness. Thus, equality for all great apes, nonhuman and human, is still arguable, despite the absence of language in our nonhuman cousins. Indeed, with our current scientific knowledge, equality should be extended to all nonhuman animals.

I hope these abstracts have stirred up your interest. I would like to hear from you what you think of them. You can register for the conference by clicking here. A cheaper ‘early bird’ registration is still possible until April 27. Looking forward to meeting you at Minding Animals this July!

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Great apes and their attitude towards other animals

Last Sunday I gave a lecture in Den Bosch on a course day about cat behaviour, organized by the Kattengedragsadviesbureau (AdvisoryBureau on CatBehaviour) of Marcellina Stolting (in cooperation with behavioural biologist Els Peeters of the University of Antwerp, Belgium). My lecture had as its title Great apes and cats and presented what is known about the way in which chimpanzees, bonobos, gorillas and orangutans relate to cats and other animals. The emphasis of my lecture was on the great apes who were used in language research, the scientific research in which it was tried to teach these great apes some form of human language.

Language research with great apes

When Darwin published his evolution theory in the 19th century and, in doing so, argued for a biological kinship between humans and other apes, scientists became very interested to study the differences and similarities between humans and other great apes. One of these issues concerned the question whether nonhuman great apes could learn some form of human language. At the beginning of the 20th century, scientists first started experiments in which they tried to teach great apes a spoken language. This was not successful, however. The best result came from the chimpanzee Viki, who in the 1950s, after 6 years of intensive training, learned to pronounce, with great difficulty, the words “papa, mama, cup” and “up.” Often she spoke them hoarse and almost inaudible and Viki also often used the words for the wrong referents.

In the 1960s, after extensive research had demonstrated that human sign language is just as complex as, and equal to human spoken language, scientists tried to teach language to apes by using sign language. They succeeded in teaching signs to apes and the apes used them in their communication with humans.

The chimpanzee Washoe, the first great ape to learn signs

The first ape who was taught signs was in 1966 the chimpanzee Washoe, who eventually learned about 150 signs that referred to all kinds of objects and actions. The success with Washoe led to other projects with signing apes: in 1972 a project started with the gorilla Koko, in 1973 another project with a chimpansee, Nim Chimpsky, and in 1978 with the orangutan Chantek. Besides this, scientists also taught chimpanzees and bonobos to use lexigrams to communicate: geometric symbols that refer to certain objects and actions. The famous bonobo Kanzi has, from the beginning of the 1980s, learned to use several hundred lexigrams.

Characteristic of most of these language projects was that the researchers tried to make these often young apes grow up in an environment that mimicked as much as possible the environment in which a human child grows up, considering that in such an environment the apes would have the best chance of picking up human language. For this reason the apes often grew up in a human family, they were dressed in clothes, learned how to brush their teeth and use a toilet, and they learned discipline and helped in keeping the house clean, by being asked things like helping with the dishes. Of course there was also lots of play with the apes and they were given dolls and other toys to play with. In the 1970s the signing apes were also regularly taken out in a car to walk outside in nature or to visit McDonalds and other places for some snacks.

In the human environment in which these apes grew up, they also came into contact with cats, dogs and other animals. In many cases these were the pets of the people in which house the apes lived. In the literature about these language projects with great apes one can find interesting information about how these apes related to other animals.

Koko and All Ball

Famous is the story about the signing gorilla Koko and her kitten All Ball. This kitten was a Manx cat, which Koko had chosen herself from a litter of abandoned kittens. Because the kitten had no tail, Koko named her, according to the researcher Penny Patterson, ALL BALL. Koko was delighted with her kitten, she petted him, played with him and did so carefully. Koko described her kitten as SOFT GOOD CAT. After several months All Ball died after a car accident and when Penny told Koko that her kitten was dead, Koko would have signed CRY, SAD and FROWN, as an expression of her grief. Watch a short  film about Koko and All Ball below.

I have to mention here, though, that not all claims that have been done by Penny Patterson about Koko’s signing are correct. In 1995 I paid a working visit to the Gorilla Foundation in Woodside, California, where Koko lives since the end of the 1970s. There I was given access to the Koko diaries in which all sign use by Koko was written down from the beginning of Project Koko. I discovered that Patterson had sadly been very selective in what she published about Koko’s signing. Sign utterances that seemed meaningful or languagelike were published, but all other, less meaningful utterances were not. Thus, I found in the unedited, unpublished data that Koko was sometimes bothered daily to make signs such as CRY, SAD and SMILE, often by presenting her with pictures and images. Koko then signed CRY CRY to a picture of a smiling man, BIRD. SAD CRY SAD CRY to a picture of a snake, and SAD CRY DEVIL to a picture of a horse. One should therefore not take the published sign utterances by Koko too seriously, given that the published data on her sign use are not reliable.

After All Ball, Koko was given a few other cats, which she related to lovingly, and which she called LIPSTICK and SMOKE, according to Patterson. Koko was also very interested in a blue jay and in several tree frogs.

The chimpanzee Nim Chimpsky

The chimpanzee Nim was also very delighted by cats. He loved holding a cat and playing with it. Regularly, a cat was brought to the special classroom in which Nim was taught signs. He then became very excited and signed CAT, CAT HUG, CAT ME. If he was then allowed to hold the cat, Nim would get a broad grin of pleasure. The humans then had to take care that Nim wouldn’t pull too hard on the cat’s tail or leg, because Nim often didn’t know his own force. This is true for all the great apes in language research: only under supervision of humans were they allowed to have contact with cats and dogs.

In his book Nim Herbert Terrace describes a fun occasion when the human Susan wanted to feed the cat some yoghurt. Nim enjoyed pretending with humans that he was feeding his dolls. He seemed to understand that that couldn’t hurt, because the dolls wouldn’t eat the food he offered, in which he usually was interested himself. When Susan wanted to feed a spoon of yoghurt to a cat, Nim took the spoon out of her hand and fed the cat himself. However, to his amazement, the cat ate the yoghurt! When Nim was then asked to feed the cat again, he offered the cat an empty spoon and then quickly took himself some yoghurt. Below you can watch a short film about Nim and cats, a short clip from the documentary movie Project Nim, which is now playing in cinemas in the US and the UK.

Nim also liked to play with dogs, whom he would then chase. He also used the sign PLAY to iniate play with cats and dogs and would even use this sign with horses.

The chimpanzee Lucy

Another signing chimpanzee, Lucy, who grew up in the house of Jane and Maurice Temerlin, was given a kitten in order to “develop her maternal instinct.” Lucy turned out to be an overprotective ‘mother’ who would carry her kitten everywhere, even when the cat itself didn’t like this. Roger Fouts describes in his book Next of kin that the cat always tried to escape when Lucy came to her, sadly without success, as Lucy always knew how to catch him. Soon the cat would fall down into a limp heap whenever Lucy came into the room, knowing that Lucy wouldn’t take notice of the cat’s own wishes. Once the cat tried to get away from Lucy by holding onto a wire cage. Lucy, however, pulled him off from there and in doing so damaged the cat’s pads on its paws. The humans took the cat away from Lucy and made it clear to Lucy that she had hurt the cat. When she eventually was given the cat again, Lucy would have taken the cat in her arms, and signed HURT HURT while pointing to the cat’s paws.

Sue Savage-Rumbaugh and the bonobo Kanzi using the lexigram board

The bonobo Kanzi

Kanzi and the other bonobos who were taught to use lexigrams to communicate by Sue Savage-Rumbaugh, also were big pals with dogs. When Kanzi was still young he would also have used lexigrams like “play” to ask the dogs to play with him. When Kanzi was older he seemed to realize that the dogs didn’t react to his lexigram use, so he then stopped using lexigrams with the dogs.

Tearing dogs apart and killing them

According to the researchers from the language projects the signing apes would also sometimes make insulting remarks about other animals. Lucy would have called a local tomcat that she didn’t like DIRTY CAT and the signing orangutan Chantek called noisy birds BAD BIRDS. Koko too, would have signed DARN BIRD and ROTTEN BIRD to a bird who was giving alarm calls for minutes on end.

Observations have also been made of less friendly behaviour by the apes towards other animals. Viki used to enjoy scaring the neighbours’ cats. Several signing chimpanzees have sometimes attacked cats. A Doberman pinscher who was used as a guard dog, was ripped apart by chimpanzees.

The chimpanzee Bruno also was destined to learn signs. He had been sent before Nim to Terrace in New York at the end of the 1960s as a sort of practice ape for his language project. After about half a year Bruno was sent back to the primate institute in Oklahoma where many of the chimpanzees who would learn signs were born. The director of the institute, Bill Lemmon, however, decided that Bruno should quickly be sent off again, this time to a childless couple, to grow up in their house. Poor Bruno, who was then 14 months old, constantly clung to his new foster mother the first few days and apparently wasn’t happy with the whole situation. A few days later he tore apart two fully grown St. Bernard dogs and a few further days later the cow of a neighbour. The dogs survived, but the cow didn’t. After 3 weeks Bruno was sent back to Oklahoma. It is remarkable, by the way, how the great apes in the language projects have been used and moved about all the time, giving little regard to their own well-being.

Nim too showed a less friendly attitude towards a dog when he was older. Nim had had by then a whole history of hardship and suffering. After the experiment with Terrace ended, Nim had been sent back to Oklahoma, where he was sold in 1982 by Lemmon to the biomedical laboratory LEMSIP in New York state, where he was planned to be used in hepatitis research. The press came out with this story and Terrace begun a campaign together with others to liberate Nim and several other chimpanzees from the laboratory. With lots of pressure from public opinion, this campaign was successful and Nim eventually was brought to the Black Beauty ranch of the American animal protectionist Cleveland Amory. (Bruno also ended up in LEMSIP, where he was injected with hepatitis and eventually died there.) On the ranch Nim was bored and lonely. He then had the habit of breaking out of his cage and go to the ranch’s manager’s house, where he’d raid the refrigerator and would lie down in a bed. Once the miniature poodle of the manager was in the house, who came running to Nim while barking hysterically. Nim then grabbed the dog and banged it against the wall several times, covering the place with blood. Elizabeth Hess, in whose book this incident is described, says that Nim killed the dog because he was frightened.

Other great apes in captivity

Besides the great apes in language research, other apes in captivity have also sometimes become friends with a cat or a dog. Already in the 1930s the gorilla Toto was adopted by the French Augusta Hoyt (Toto had been taken from Africa, her mother had been killed in a hunt). Toto also grew up like a human child in the house of Hoyt, who moved to Cuba with the gorilla. When Toto was 4 or 5 years old, she befriended the kitten Principe, which she carried everywhere. Sadly, when Toto became older and less manageable, she was sold to the Ringling Brothers and Barnum and Bailey Circus.

The orangutan Tonda and the cat TK

Eric's impression of Tonda and TK

Of a more recent date is the friendship between the orangutan Tonda and the cat TK. The female Sumatran orangutan Tondalayo lived with another orangutan in the Zooworld zoo in Panama City, Florida. In 2005 her orang companion died, after which Tonda became depressed. She didn’t eat and wasn’t interested in anything anymore. Tonda was already an elderly orangutan and she was not in such good health. For some reason she was considered too old for a new orangutan companion and she was too frail to be sent off to another location. Her human caretakers didn’t know what to do and feared that she might die of misery. They were inspired, however, by Koko’s story and searched a cat that would be appropriate for Tonda: a playful yet docile one-year-old tabby cat T.K. (short for Tonda’s Kitten). The orang and the cat became friends. They ate together and slept together. They played and cuddled and Tonda always watched her cat carefully, the way a mother watches over her child. Tonda also fed the cat and when it was time for a nap, she would take the cat under her blanket. Tonda get very attached to TK and she became angry when her human caretakers took the cat away. Tonda’s health also improved. In 2009 Tonda died quietly, after which the cat TK was down that his companion was no longer there. Click here for a short film about Tonda and TK.

The chimpanzee Anjana and the cubs

Eric's impression of Anjana and a white tiger cub

The Institute of Greatly Endangered and Rare Species (TIGERS) in Myrtle Beach, South Carolina, is a sanctuary that takes care of all kinds of exotic animals and gives education about them. One of their animals is the female chimpanzee Anjana. She was inseparable of her human caretaker China York. Thus, Anjana was present when York took care of other animals, such as two white tiger cubs who were separated from their mother in 2008 after a hurricane. The then 2-year-old Anjana imitated the care of the tiger cubs and related to the cubs in a very friendly way. Anjana would feed them milk, lay with them and act like a surrogate mother. She cuddled them, played with them, enjoyed holding them and when she heard them cry because they were hungry, she stuck a finger in their mouth like a pacifier. Besides these tiger cubs, Anjana has helped raising leopards, lions and orangutans in the sanctuary. Watch a short film about Anjana and the cubs below.

Killing and eating other animals

Besides these friendships between great apes in captivity and other animals, it is also known that all great apes kill and eat animals that have entered their enclosure. They do so with animals such as squirrels, rats, mice, and birds. This was shown in a recent study by Ross, Holmes and Lonsdorf (2009) in which caretakers from all kinds of zoos and sanctuaries in the US and Canada were asked about their observations. Chimpanzees in particular also used the carcass of the animal in their displays towards their conspecifics. Chimpanzees and bonobos more often showed aggressive behaviour towards animals that had entered their enclosure than gorillas and orangutans. Below you can see a short film about chimpanzees in a zoo in St.Louis, hunting a cat in their enclosure.

It is remarkable that gorillas in captivity also kill and eat vertebrate animals, as this has up to now never been observed in wild gorillas. It has been known, however, that gorillas in captivity eat meat from vertebrate animals that they are offered. The signing gorilla Koko also was offered hamburgers and ate them.

The bonobo Kuni and the starling

In contrast with this is the story about the bonobo Kuni and the starling, which is mentioned in several books by Frans de Waal. Somewhere in the 1990s a starling flew against the windows of the bonobo enclosure in the Twycross Zoo in England. The 7-year-old female bonobo Kuni caught the starling, at which a human caretaker urged her to let the starling go. Kuni took the bird outside and put it on its paws, where it remained immobile. Kuni then threw the starling up a bit, but the bird just fluttered a little. Then Kuni took the starling into one hand and climbed to the top of the highest tree in the outdoor enclosure and when she reached the top Kuni held on to it with her feet and then used both hands to unfold the starlings wings carefully, after which she threw the bird as far away as she could in the direction beyond the moat surrounding the enclosure. Unfortunately, the starling still fell just inside the bonobo enclosure. Kuni then climbed down and protected the starling against a curious juvenile bonobo. At the end of the day the starling was nowhere to be seen: it is assumed that the starling had eventually been able to fly away.

Great apes in the wild and other animals

Chimpanzees and baboons

Jane Goodall calls the interactions between chimpanzees and baboons the most varied and complex of any two other species of animals in the animal kingdom. First of all, play often takes place between especially young chimpanzees and young baboons. The play predominantly exists of chasing each other and hitting each other playfully. Often, however, the play ends up in agression. The chimpanzees and baboons then chase each other while stamping and slapping and the chimpanzees throw rocks and sticks at the baboons. Sometimes actual attacks take place, in which the animals hit each other. Besides play, Goodall has also observed the old baboon Job regularly being groomed by chimpanzees. Also, sometimes the baboons startle a chimpanzee, who then utters a threat-bark, causing the baboon to cower submissively. The chimpanzee would then touch the baboon quietly in reassurance.

Gilka and Goblina

In Gombe Goodall was able to observe the special relationship between the chimpanzee Gilka and the baboon Goblina. When Gilka was 4.5 years old she had at that time no other young chimpanzees to play with and her mother Olly was often fishing for termites for hours on end. Gilka therefore became bored and somewhat lethargic. One day she hears a troop of baboons, goes over to them and Goblina comes over to her (Goblina’s mother had died, but she did have enough baboon playmates). Gilka and Goblina look at each other, put an arm around each other and they start playing. They wrestle and pat each other. They tickle each other with their fingers and give each other playful nibbles with their mouth, all accompanied by soft laughter.

Different from the normal play between chimpanzees and baboons, the play between Gilka and Goblina did not become aggressive, it mostly was gentle and careful. The friendship lasted for a full year. Gilka then travels with her mother Olly to another location and only returns after half a year. Goblina had by then reached adolescence (baboons mature quicker than chimpanzees) and had become less playful and the friendship was not revived. Later two adult chimpanzees would kill Goblina’s first child. Goblina watched the event while calling loudly.

Sexual behaviour between chimpanzees and baboons

Goodall also describes sexual behaviours between the chimpanzees and baboons in Gombe. Already when the chimpanzee Flint was 8 months old, did he show interest in the sexual swellings of the female baboons. Often they would then present themselves to him and allowed him to touch their pink bottoms. Female baboons would also present themselves to other interested young, but also adult male chimpanzees.

Young male baboons also get excited by the genital swellings of adolescent female chimpanzees. They grab their ankles and try to copulate. The baboon Ajax mounted the 9-year-old female chimpanzee Moeza, who wasn’t interested, but let him go, because she was sad that her mother had died. Ajax was unsuccessful in actual copulation, however. When Flint was 7 years old he copulated with the female baboon Apple. He showed her his erection, Apple presented herself and copulation took place.

Bonobos and other animals

It has been observed of wild bonobos that they sometimes groom monkeys. Play between bonobos and monkeys has also been observed. In the Wamba area in Congo observations have also been made of bonobos playing in a less friendly way with monkeys. The bonobos seemed to see the apes as toys. They would inspect them, groom them and mount them. They even threw them in the air and swung them with their tails, causing the monkeys to bang their heads. Two young monkeys didn’t survive this rough type of play.

Other animals as food

Many different animals are being eaten as food by great apes. Chimpanzees hunt red colobus monkeys, vervet monkeys, baboons, bushbabies (where the chimpanzees make spears out of branches to impale the bushbabies in hollow trees), bush antelopes, bushbucks, warthogs, bushpigs and even human children. Watch a film about chimpanzees hunting red colobus monkeys below.

Bonobos hunt for redtail monkeys, vervets, black mangabeys, reptiles, insects, earthworms and birds’ eggs. Gorillas in the wild have only been observed to eat invertebrate animals, such as ants, termites, worms, caterpillars and snails. Orangutans eat all kinds of insects, but also small birds and mammals. They hunt grey tree rats, slow loris and even gibbons.

It has to be mentioned, though, that all great apes predominatly eat fruits and plants and other animals make up only a few percentages of their diet. Bonobos and orangutans are more opportunistic hunters, whereas chimpanzees regularly go out together on hunts. Cannibalism has also been observed in all four great apes, where young apes in particular are eaten.

Big cats and great apes

Big cats are the natural enemies of great apes in the wild. Leopards hunt all four great ape species. Lions hunt for chimpanzees and tigers on Sumatra for orangutans. The chimpanzees and bonobos drive the big cats away by hurling sticks, branches and stones and using their intimidation displays. Famous are the experiments by the Dutch ethologist Adriaan Kortlandt, who put a stuffed leopard with a baby chimpanzee doll in its claws. The chimpanzees in reaction used sticks and branches as clubs and lots of aggressive behaviour towards the stuffed leopard. Watch a short film about this experiment below.

Besides big cats, snakes hunt bonobos and crocodiles orangutans. However, for all great apes humans are the most important predator.

Conclusion: They’re just like humans

When we look at the way in which nonhuman great apes relate to cats and other animals, we can conclude the following. Although only humans keep other animals as pets for their own pleasure, nonhuman great apes that live with humans in captivity can get strong ties of affection with cats, dogs and other animals. It is, however, often necessary that the apes are under the supervision of humans when they play with other animals, because the apes often don’t know their own (much greater) strength. Negative attitudes and aggressive behaviour towards other animals also exists in great apes in captivity, where they attack cats and dogs and sometimes even kill them. Usually, however, there is an explanation for this less friendly behaviour: the apes are frightened or feel threatened or have been treated badly by humans. It seems like great apes in captivity are similar to humans: if the apes learn with human guidance to treat cats and dogs well, they will do so. Only when other motives play a part (fear, threat, negligence), will great apes in captivity treat other animals badly, which may also be the case with humans. At the same time, however, all great apes in captivity will kill and eat birds and mammals that have entered their enclosure.

Finally, in the wild, great apes will sometimes play with other animals, but often this turns to aggression. All great apes, and especially chimpanzees and bonobos, will hunt and eat many different animals. We may possibly see a link there with how our own human ancestors related to animals in the past.

Invite me to give this lecture!

If you’d like me to give this lecture at your own organization you can contact me. My email address is: estebanyes@gmail.com


– Roger Fouts (with S.T. Mills). (1997). Next of kin. What chimpanzees have taught me about who we are. New York: William Morrow & Company.

– Jane Goodall. (1971). In the shadow of man. London: Wm. Collins.

– Jane Goodall. (1986). The chimpanzees of Gombe. Patterns of behavior. Cambridge, MA: The Belknap Press of Harvard University Press.

– Jane Goodall. (1990). Through a window. My thirty years with the chimpanzees of Gombe. Boston: Houghton Mifflin Company.

– Elizabeth Hess. (2008). Nim Chimpsky. The chimp who would be human. Nerw York: Bantam Books.

– Eugene Linden. (1981). Apes, men, and language. Harmondsworth: Penguin Books.

– Anna Michel. (1980). The story of Nim. The chimp who learned language. New York: Alfred A. Knopf.

– Francine Patterson. (1987). Koko’s story. New York: Scholastic, Inc.

– Francine Patterson & Eugene Linden. (1981). The education of Koko. New York: Holt, Rhinehart and Winston.

– Esteban Rivas. (2003). GIMME GIMME GIMME. The recent signing behaviour of chimpanzees (Pan troglodytes) in interactions with longtime human companions. Radboud Universiteit Nijmegen: proefschrift.

– S.R. Ross, A.N. Holmes & E.V. Lonsdorf. (2009). Interactions between zoo-housed great apes and local wildlife. American Journal of Primatology, 71, 458-465.

– Sue Savage-Rumbaugh, Stuart G. Shanker & Talbot J. Taylor. (1998). Apes, language, and the human mind. Oxford: Oxford University Press.

– Herbert Terrace. (1979). Nim. New York: Alfred A. Knopf.

– Frans de Waal. (2009). The age of empathy. Nature’s lessons for a kinder society. New York: Three Rivers Press.

– Frans de Waal en Frans Lanting (1997). Bonobo. The forgotten ape. Berkeley: University of California Press.


Filed under Animal Communication, Animal Ethics, Language research with animals, Lectures and courses

Registration for new Hovo courses now open!

In 2011 I will be presenting my course Communicatie en taal bij dieren at still further institutes of the Hoger Onderwijs Voor Ouderen – HOVO (Higher Education for older people). My course on the many wonders of animal communication and the intriguing history of scientific research on possibly teaching a human language to nonhuman animals, has received wide interest.

This new year I will be giving my course at the HOVO Brabant Seniorenacademie at their location at Tilburg University. It will consist of 10 lessons on Thursday morning, starting on 27 January and ending on 7 April 2011. For the HOVO Leiden I will be giving the course in 8 lessons on Tuesday afternoon, starting on 22 February, with the last lesson on 12 April 2011. Registration for both courses is now open. You can find more information and register by clicking here for HOVO Brabant and by clicking here for HOVO Leiden.

The programme of my course Communicatie en taal bij dieren will consist of the following lectures:

  1. Communication and human language: Characteristics and definitions. Language development in human children.
  2. Natural communication of animals. Goals and modalities. The honeybee dances. The alarm calls of vervet monkeys and prairie dogs.
  3. Natural communication of animals. The songs and calls of birds. The communication of wales and other animals.
  4. Natural communication of the great apes: chimpanzees, gorillas, orangutans and bonobos.
  5. Language research with great apes. History. Experiments with spoken language and sign language. The world famous signing apes: the chimpanzee Washoe, the gorilla Koko, and the orangutan Chantek.
  6. The ape language controversy. Research with the signing chimpanzee Nim. Methodological pitfalls and errors in interpretations and conclusions.
  7. The recent use of signs by chimpanzees in interactions with humans. Systematic study and conclusions with regard to the linguistic nature of signing by great apes.
  8. The language research with the world famous Kanzi and other bonobos who communicate with lexigrams. Interpretations and conclusions.
  9. Language research with other animals: dolphins, sealions, Alex the parrot.
  10. How did human language evolve?

The courses will be given in the Dutch language, but passive knowledge of English is required, given that some of the videos and films that I’ll be showing at the lectures are in English without subtitles. Accompanying study material will consist of a reader/syllabus with major articles or book excerpts on the subjects of animal communication and language research with nonhuman animals. The powerpoint presentation of each lecture will be made available to those attending the course.

If Tilburg or Leiden are too far from where you live, don’t worry. I am in touch with several other HOVO institutes about giving my course in the Summer or Autumn of 2011. I’m looking forward to meeting you at one of my courses!

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Filed under Animal Communication, Language research with animals, Lectures and courses