Mijn lezingen op de Minding Animals Conferentie

Van woensdag 4 juli tot en met vrijdag 6 juli wordt de tweede Minding Animals Conference gehouden in Utrecht, mede georganiseerd door het Instituut voor Ethiek en de Faculteit Diergeneeskunde van de Universiteit Utrecht. Voor meer informatie over de opzet en het doel van deze conferentie, lees mijn eerdere bericht uit januari over Minding Animals.

Recentelijk zijn de twee samenvattingen die ik had ingediend voor twee lezingen op de conferentie geaccepteerd. Ze zullen worden gepresenteerd tijdens twee van de parallele sessies. Hieronder vindt U deze samenvattingen. Ze zijn in het Engels, aangezien ook de lezingen in het Engels zullen worden gegeven.

De eerste lezing valt onder het thema Animal Capacities (Dierlijke Vermogens), sessie 2b: Higher order cognitive capacities in animals (Cognitieve vermogens van dieren).

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.

De tweede lezing zal deel zijn van het thema Animal Ethics (DierEthiek), sessie 4a: The moral relevance of socio-cognitive abilities (De morele relevantie van socio-cognitieve vermogens).

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.

Ik hoop dat deze samenvattingen Uw interesse hebben gewekt. Ik zou graag Uw mening over de inhoud ervan horen. Om zich in te schrijven voor de conferentie, klik hier. Een goedkopere ‘early bird’ inschrijving is nog mogelijk tot 27 april. Tot ziens op Minding Animals in juli!


Over estebanrivas

Esteban Rivas is a psychologist and philosopher who has worked with signing chimpanzees. He is currently giving lectures and courses on ape language research, animal communication and cognition, and animal ethics.
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