In response to:

Can Chimps Converse?: An Exchange from the November 24, 2011 issue


To the Editors:

In response to my previous letter [NYR, November 24, 2011], Peter Singer claims that “Herbert Terrace ignores the extensive research carried out subsequent to his 1979 paper that contradicts his conclusion that ape signing is mere imitation….”

Singer’s statement is untrue. I’m keenly aware of such research, although I view most of it as gossip
1 because it is based on anecdotal logic: i.e., If Dr. X reports that chimpanzee Y signed word1, word2, word3, etc., such signing is automatically equated with human language.

Sue Savage-Rumbaugh, the best known of Singer’s references, provides an exceptionally clear example of primate anthropomorphism that Singer believes meets “the highest standards of scientific rigor.” At the beginning of her book on language learning by bonobos she states:

When I observe a bonobo, it is as though I am standing at the precipice of the human soul, peering deep into some distant part of myself. This is a perception I cannot shake off or dissuade myself from, no matter how often I try to tell myself that I have no definitive scientific basis for these impressions.2

In effect, she and Singer believe that anthropomorphic opinion trumps scientific conclusions when, clearly, they don’t. As I’ve argued many times, the question about ape language boils down to our use of language in two senses: imperative and declarative.3

Singer and I agree that apes and human infants can learn to use arbitrary symbols as imperatives. They can cry and otherwise signal that they want food, drinks, hugs, etc. But beyond this, Singer and I part company.

He does not agree, as I do, and as all scientific research on the subject confirms, that only humans can use language in the declarative sense. Unlike chimpanzees, only humans can engage in bidirectional conversation in which information is exchanged for its own sake. I have yet to see a shred of scientific evidence of such conversational “turn-taking” among apes except (and this is key) as anthropomorphized anecdotes—anecdotes that may make some of us feel better about our place in the tree of life but won’t make us any smarter about the origins of language, how it is learned, and what it means to the human mind.

Herbert S. Terrace
Professor of Psychology and Psychiatry
Columbia University
New York City

Peter Singer replies:

It is grossly unfair to Sue Savage-Rumbaugh to cite, as evidence that her work is unscientific, a passage from one of her books in which she speculates about whether a bonobo has something resembling a human soul. Of course she has no scientific basis for such speculations, and as the passage shows, she knows that very well. The passage has nothing to do with the issue that divides Professor Terrace and myself, which is whether apes are capable of language.

Terrace claims to be “keenly aware” of current research involving language use in great apes. If so, he has presumably read the paper “Nonhuman Primates Do Declare! A Comparison of Declarative Symbol and Gesture Use in Two Children, Two Bonobos, and a Chimpanzee,” written by Savage-Rumbaugh, together with Heidi Lyn, Patricia Greenfield, Kristen Gillespie-Lynch, and William Hopkins, which was published in the leading peer-reviewed journal, Language and Communication, in January 2011.

As the title suggests, this paper directly contradicts the claim Terrace makes in his letter that “only humans can use language in the declarative sense.” Our exchange would have been more productive if Terrace had indicated how he can dismiss the findings of this rigorous quantitative study (or of the many other articles that Savage-Rumbaugh and other scientists have published in peer-reviewed journals over the past thirty years) as “gossip” or “anecdote.”