"Chimps have tons to say but can't say it"

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Nicholas Wade, "Deciphering the Chatter of Monkeys", NYT, 1/11/209, starts out with a Dr. Dolittle trope that may raise a red flag or two among those who are tired of facile anthropomorphizing in stories about animal communication:

Walking through the Tai forest of Ivory Coast, Klaus Zuberbühler could hear the calls of the Diana monkeys, but the babble held no meaning for him.

That was in 1990. Today, after nearly 20 years of studying animal communication, he can translate the forest’s sounds. This call means a Diana monkey has seen a leopard. That one means it has sighted another predator, the crowned eagle. “In our experience time and again, it’s a humbling experience to realize there is so much more information being passed in ways which hadn’t been noticed before,” said Dr. Zuberbühler, a psychologist at the University of St. Andrews in Scotland.

Do apes and monkeys have a secret language that has not yet been decrypted? And if so, will it resolve the mystery of how the human faculty for language evolved?

But there really are referentially specific alarm calls of that kind, of course, even if they don't amount to a Dolittle-style "secret language".  So having lured its readers in, the article settles down to a sensible sort of survey:

Biologists have approached the issue in two ways, by trying to teach human language to chimpanzees and other species, and by listening to animals in the wild. […]

But with a few exceptions, teaching animals human language has proved to be a dead end. They should speak, perhaps, but they do not. They can communicate very expressively — think how definitely dogs can make their desires known — but they do not link symbolic sounds together in sentences or have anything close to language.

Better insights have come from listening to the sounds made by animals in the wild. Vervet monkeys were found in 1980 to have specific alarm calls for their most serious predators. […]

Wade quickly surveys Cheney & Seyfarth's vervet work, their baboon work, and Zuberbühler's work with Campbell's monkeys and putty-nosed monkey. His conclusion, though, is that

Monkeys and apes possess many of the faculties that underlie language. They hear and interpret sequences of sounds much like people do. They have good control over their vocal tract and could produce much the same range of sounds as humans. But they cannot bring it all together.

It's possible to question this way of putting it. It's not so clear that monkeys and apes have "good [conscious] control over their vocal tract" or that they "could produce much the same range of sounds as humans" — for example, it's effectively impossible to teach chimps to sing, as far as I know.  There's nothing crucially human or linguistic about this, obviously. Many birds are excellent vocal mimics, and dogs can be taught to produce specific pitch contours on cue. Gibbons are excellent singers, but as far as I know, their song patterns are instinctual rather than learned. Still, if you or I were given a chimp's vocal tract and a chimp's degree of cortical control over it, I bet that we could probably learn to do something approximately like talking.

And Wade makes the point that I've always thought is the most important thing about the evolution of language:

This is particularly surprising because language is so useful to a social species. Once the infrastructure of language is in place, as is almost the case with monkeys and apes, the faculty might be expected to develop very quickly by evolutionary standards. Yet monkeys have been around for 30 million years without saying a single sentence. Chimps, too, have nothing resembling language, though they shared a common ancestor with humans just five million years ago. What is it that has kept all other primates locked in the prison of their own thoughts?

He cites Seyfarth and Cheney's idea that the crucial missing ingredient is

… a “theory of mind”; the recognition that others have thoughts. Since a baboon does not know or worry about what another baboon knows, it has no urge to share its knowledge.

Again, this way of putting it may not be quite right. Cheney and Seyfarth use Premack and Woodruff's 1978 definition of theory of mind, which goes beyond "know[ing] or worry[ing] about what another … knows".  In addition to attributing mental states such as beliefs, knowledge and emotions to self and others, and recognizing  that the mental states of others may differ from one's own, a "theory of mind" in this sense also crucially involves the ability to use these attributed states to explain and predict behavior, and to predict how such mental states would be affected by hypothetical actions.  Still, Wade's formula is short and clear and close enough for the purpose.

Wade ends with another theory, from Marc Hauser:

“For whatever reason, maybe accident, our brains are promiscuous in a way that animal brains are not, and once this emerges it’s explosive,” he said.

In animal brains, by contrast, each neural system seems to be locked in place and cannot interact freely with others. “Chimps have tons to say but can’t say it,” Dr. Hauser said. Chimpanzees can read each other’s goals and intentions, and do lots of political strategizing, for which language would be very useful. But the neural systems that compute these complex social interactions have not been married to language.

Alas, at the end of his sensible survey, Wade can't resist a final dose of Dolittlery:

“I’m becoming pessimistic,” [Hauser] said of the efforts to explore whether animals have a form of language. “I conclude that the methods we have are just impoverished and won’t get us to where we want to be as far as demonstrating anything like semantics or syntax.”

Yet, as is evident from Dr. Zuberbühler’s research, there are many seemingly meaningless sounds in the forest that convey information in ways perhaps akin to language.

It would be uncharitable to say that I sometimes feel the same way as I wander through the newspapers, so instead I'll say that this is a remarkably good article, in comparison to many that I've seen on similar topics.


  1. Barbara Partee said,

    January 12, 2010 @ 1:50 am

    Oh, Mark, that last sentence is such a beautifully honed knife.

  2. MJ said,

    January 12, 2010 @ 3:10 am

    I don't get the 'theory of mind' point. I mean, presumably, we evolved from some species that did not possess a theory of mind. So the fact that monkeys (or apes even) don't have such a thing hardly explains why they don't have language. If language is so great, evolutionarily speaking, then any sufficient condition for such is great, evolutionarily speaking, or so one would think. So saying 'they don't have language cuz they don't have a theory of mind' only pushes the explanatory question back to 'why don't they have a theory of mind?'

    [(myl) Exactly. But a "theory of mind" in the Premack/Woodruff sense is hard — look at the difficulty that AI researchers have in imitating this aspect of human communication, outside of toy worlds.

    The evolutionary puzzle here is even worse than Wade suggests. I gather that the communications systems of reef quid and cuttlefish involve something like two dozen qualitatively distinct symbols that can be combined in a roughly conjunctive way, with modulation of intensity. That system presumably evolved several hundred million years ago. As far as I can tell, none of the systems of non-human primate communications involve larger numbers of distinct symbols, or more complex modes of combination.

    If you believe that the complexity and flexibility of (a system like) human communication is an adaptive trait, then it's impossible to believe that evolution has been stymied for 400 million years or so by problems in the I/O system, especially since the basic capabilities for symbol production and perception (whether vocal or visual) have evolved independently many times to solve other problems.

    You might believe a "can't get there from here" story — elephants' trunks are great, once you've got them, but maybe just having a slightly longer nose that you can wiggle a bit better isn't usually valuable enough to pull evolution in that direction. That's (part of) Terence Deacon's theory, as I understand it. He argues that it's hard to develop a general symbolic communications system because the first stages are actually maladaptive in most cases.

    But the "theory of mind" theory has the advantage of shifting the evolutionary onus onto something that really does seem to be hard to develop.]

  3. Rubrick said,

    January 12, 2010 @ 3:29 am

    Because they don't have language, obviously. Duh.

  4. phspaelti said,

    January 12, 2010 @ 4:21 am

    I thought you should have also included the following quote:

    Dr. Zuberbühler said. “There is nothing to talk about for a chimp because he has no interest in talking about it.”

    Which makes a nice contrast to:

    “Chimps have tons to say but can’t say it,” Dr. Hauser said.

    So Chimps have lots to say, but they just can't say it. Or maybe they just don't talk because they have nothing to say. Yep. That just about covers it.

    [(myl) In fairness to Klaus and Marc, these statements are not quite as contradictory as they might appear to be in the context of this article. I take it that "no interest in talking about it" is a sort of motivational expression of the "inadequate theory of mind" idea — in any case, it's quite different from having nothing to say. For us humans, "I don't want to talk about it" usually means something like "I have a lot of ideas and feelings on this subject, but I don't think you'd understand, or that it would do me any good if you did". For the chimp, that might mean "I have a lot of ideas and feelings on this subject, but I don't realize that you don't share them, or that there are things that I could do to cause you to understand that I have them".

    Hauser's quote is related to the "neural promiscuity" theory, which doesn't contradict the idea that the design of communicative acts is hard, but just emphasizes a different idea, namely that some brain systems may not be well enough connected. Those are ideas about entirely different sorts of things — one is an idea about mental life, the other an idea about the functioning of the brain.]

  5. Nathan Myers said,

    January 12, 2010 @ 5:33 am

    Some among us have "tons to say" (or probably think they do) but won't say it. Mostly they are teenagers.

    Teenager as model of chimpanzee? Chimpanzee as model of teenager?

  6. Gazman said,

    January 12, 2010 @ 5:45 am

    But, as he says in the article, other animals (apart from humans) DO have language. it is fit to purpose. Birds call to alert for various threats or to indicate the presence of food. The need for security, shelter and food is all the language they need. Surely it's the same with 'higher' forms like the monkey. We have language to express complex concepts which we feel we need to express but we live in a complex society. Perhaps we just talk too much and should be a little more like Mr Ed and only speak when we need to! And maybe this is what primates are doing.

    [(myl) Troll alarm! Troll alarm!

    Seriously, this is a self-refuting comment. Its first sentence, though logically and empirically deficient, is qualitatively more complex than anything Klaus Zuberbühler has ever attributed to a monkey.

    And humans who live in simpler societies have (and use) languages that are every bit as complex as those who live in complex ones. (Maybe more complex, since the languages of larger societies tend to be morphologically simpler.) Adopting monkeys into human society doesn't cause them to say more complex things.

    The notion that non-human animals would use more elaborated or communicatively effective forms of language if only they "needed" to is empirically false. There are many experimental demonstrations of this.]

  7. MattF said,

    January 12, 2010 @ 8:55 am

    The notion that the early stages of 'linguification' must be actually maladaptive is really interesting. Is the theory that proto-humans spent all their time and attention gossiping and didn't notice that leopard sneaking up on them from behind?

  8. Mr Fnortner said,

    January 12, 2010 @ 10:31 am

    It seems that all our hammers are reaching for the nail of voice communication. Of course. We speak, so we search for why chimps do not. At some moment in the past, no primate spoke, and yet if Mr. Wade makes any valid point at all it is that "neural systems that compute…complex social interactions have not been married to language." This would have been true for the ancestors of all of us. At a decisive moment, a bridge formed to the vocal apparatus. Why vocal? Why must it have been vocal? It is because we now speak so therefore we believe there could be no other way? Perhaps the bridge could have been to performances of another body part or system. A different happy accident could have us all changing color like an octopus. We don't yet know what evolution will bring to chimps.

  9. dwmacg said,

    January 12, 2010 @ 10:54 am

    There's a very extensive discussion here on the key difference between humans and other great apes that explains why humans have languages and the other don't. For Tomasello et al. it's shared intentionality:

    "We propose that human beings, and only human
    beings, are biologically adapted for participating in collaborative
    activities involving shared goals and socially coordinated
    action plans (joint intentions). Interactions of
    this type require not only an understanding of the goals, intentions,
    and perceptions of other persons, but also, in addition,
    a motivation to share these things in interaction with
    others – and perhaps special forms of dialogic cognitive
    representation for doing so. The motivations and skills for
    participating in this kind of “we” intentionality are woven
    into the earliest stages of human ontogeny and underlie
    young children’s developing ability to participate in the collectivity
    that is human cognition."

    In addition to the main article, there's about 30 pages of response, so I think (from an outsider's perspective) that it gives a fairly good portrait of how the field is thinking about the issue.

  10. dwmacg said,

    January 12, 2010 @ 10:56 am

    @Mr. Fnortner,

    Good point about non-vocal forms of communication. Tomasello makes the point elsewhere that the proper great-ape analogue (or precursor) for language is their gestures, not their vocalizations.

    (In case you can't tell, I've been reading a lot of Tomasello recently.)

  11. Phil Jennings said,

    January 12, 2010 @ 10:56 am

    The comment about chimps being unable to sing inspires me to pose a somewhat off-thread hypothesis. Our cat flees to the basement whenever my wife goes to the piano to sing in her powerful soprano. I have sometimes suggested to soprano friends of mine that they should visit the cat house at the nearest zoo to find out what happens when they break into song, preferrably something operatic. My theory, so far untested, is that early songsters in the human lineage could form a group "choral" defense against individual stalking cats, a strategy which would naturally develop into evening sings around the campfire to keep the bad things away.

  12. Adrian Morgan said,

    January 12, 2010 @ 11:12 am

    I've long been bothered by the problem (as I perceive it) that the term "theory of mind" is used as a cover term for a range of psychological phenomena that are far more different than they are similar. It seems to me that in almost all discussions of the topic, the broadness of the term and the implications for its usefulness are not given enough consideration.

    In particular, theory of mind refers variously to: (a) The ability to recognise that the thoughts, opinions, perspectives, tastes, etc of others differ from one's own; (b) The ability to predict what someone with a different perspective would be thinking in a hypothetical situation; (c) The ability to predict what someone is thinking by observing their actions.

    Sometimes these different senses are in conflict with each other, for example the instinct that we know what other people are thinking by observing their actions is very often the main barrier to acknowledging that their perspectives differ from our own. Human interactions are full of examples of precisely this.

  13. Dan Lufkin said,

    January 12, 2010 @ 11:51 am

    These discussions never seem to spend much time on the obverse: how well animals are capable of understanding human language, which is certainly a component of innate language ability. In my experience, lots of dogs can understand a dozen or so words in varied contexts, so there must be a listening and interpreting mechanism at work in there. Some horses are good at it, too. Cats understand everything just fine, but don't care to participate.

    Anecdote alert: We once had a Border Collie who understood go over and go under and again and could say mama and oreo and moo like a cow and gobble like a turkey, all on command. She really seemed to get the idea of imitation vocalizing and loved to practice and show off. Perhaps diagnostically, she was epileptic and lived only four years.

    [(myl) See e.g. here.]

  14. Mark F said,

    January 12, 2010 @ 12:19 pm

    Mr. Fnortner —

    But non-voice communication in apes has famously been investigated for decades, and they're not really all that good at it. I'm sure in nature they have a repertoire of body language, but that's not language either.

  15. Mark P said,

    January 12, 2010 @ 12:24 pm

    Mr Fnortner makes a good point, I think. For us, language is obviously highly adaptive and a hallmark of true intelligence. But maybe that's only because we haven't destroyed ourselves yet. The fact that we (and apparently only we) have it does not necessarily make it adaptive, or good, or the fundamental requirement for intelligence – it just makes it human.

  16. Robert E. Harris said,

    January 12, 2010 @ 2:06 pm

    Re Myers comment: There are older folks who have nothing to say but say it at great length. Maybe they are releasing all that talk saved from their teen years. I saw this in 44 years of faculty meetings.

  17. Forrest said,

    January 12, 2010 @ 2:59 pm

    I thought the "theory of mind theory" was very insightful – and have emailed that to a few friends who would be interested in reading it.

    Mr Zuberbühler seems to be implying that having calls for predators is akin to language. To my mind, this isn't terribly different from a gazelle stotting, or, many species of birds giving different food and alarm calls. I've read that many aphasics have no trouble swearing when they stub their toe…

    Another comment quotes the suggestion that

    "We propose that human beings, and only human beings, are biologically adapted for participating in collaborative activities involving shared goals and socially coordinated action plans (joint intentions). Interactions of this type require not only an understanding of the goals, intentions, and perceptions of other persons, but also, in addition, a motivation to share these things in interaction with others – and perhaps special forms of dialogic cognitive representation for doing so. The motivations and skills for participating in this kind of “we” intentionality are woven into the earliest stages of human ontogeny and underlie young children’s developing ability to participate in the collectivity that is human cognition."

    This doesn't seem very satisfying, either. Sailfish eat bait fish, and often do this in groups. When they hunt solo, they change their color to confuse their pray, but when they hunt in groups, they display a wider range of colors. They'll change color to coordinate their attacks, so that others know when one of them is about to charge the bait fish … and can avoid being stabbed by its "sword." If this isn't a shared goal, it's a common one.

    Planet Earth has footage of a group of small mammals ( otters ) harassing an alligator ( or crocodile? ) and chasing it back into the water. This is teamwork to achieve a shared goal, yet these creatures don't have language.

  18. Mr Fnortner said,

    January 12, 2010 @ 3:35 pm

    If Wade is right that "each neural system seems to be locked in place and cannot interact freely with others," the implication is clear that our hominin forebears were equally "locked in." We have (accidentally) achieved a marvelous thing in speech to break out of the communicative isolation of our ancestors. I wonder if speech was the only, the best, or the expected evolutionary outcome for the proto-chimp/human? Would an alien researcher observe us and remark, "Oh, look. How quaint. They communicate by expelling vibrating air from inside their bodies. Did anybody bring a meter we can measure this with?"

  19. Sparky said,

    January 12, 2010 @ 3:56 pm

    " . . . for example, it's effectively impossible to teach chimps to sing, as far as I know."

    Has anybody tried? And have you tried to find out?

    [(myl) I've tried to find out, by asking people that I know that do research on chimps. I haven't found anyone who thought it would be possible, but I also haven't found anyone who gave it a very extensive trial.

    On the other hand, I'm sure that if the various apes raised in quasi-family situations had started singing in imitation of lullabies etc., it would have been widely publicized.

    Teaching dogs to "sing" is not all that hard, and is something that I've seen done more than once.]

  20. Neal Goldfarb said,

    January 12, 2010 @ 11:57 pm

    With all the discussion of language evolution, I just thought I'd throw in a link to Babel's Dawn, which is devoted to the issue.

  21. Illness and disability « Arnold Zwicky's Blog said,

    January 13, 2010 @ 12:52 pm

    […] and disability By arnoldzwicky Along with an article on the failure of other primates to develop a system of communication comparable to human language, […]

  22. Forrest said,

    January 14, 2010 @ 1:55 pm

    I've been thinking about this … and "baboons lack a theory of mind, so natural selection would disfavor language development" doesn't seem very convincing anymore. I'm not sure exactly where the cut-off is between individuals who posses a theory of mind and those who don't, but after some thought, I'm pretty sure Franz de Waal is right, and primates must have at least rudimentary theories of mind.

    My cat, Parsley likes to ambush things. When I walk into the living room from the hallway, she likes to hide behind the corner of the desk to pounce on me. I'm tall enough to see over it, but not around, and it's plain to see that she gets excited when she thinks I don't see her. That means I don't know about her, and it's going to be an effective ambush.

    There are two ways I can explain this:

    * She's modeling what knowledge exists in my head, based on the assumption that I know about what I see, and that I can't see her from that angle.

    * This is a simple instinct, like moth's flying toward light. In cats: Hide behind something at a 90 degree angle and appear happy, when something animate comes your way.

    I think "theory of mind" is more parsimonious. If a cat is concerned with what other creatures know, at least in this type of case, surely a baboon can be expected to have more complexity about what its mates know?

    Also, as you would expect of a predator, she appears to have a pretty good "agent-detection system." Parsley is aroused by sudden, unexpected noises, and by things that move in ways Newton's laws wouldn't predict. The latter helps her catch yummy mice, but avoid being taken in by boring toys like rolling balls.

  23. Matt McIrvin said,

    January 15, 2010 @ 11:06 am

    If I understand the developmental research correctly, human children start to develop language long before they have much ability to model the thoughts of other people–before they understand that others can, say, lack information about the world that they possess, or see a different view of an object than they see. This happens surprisingly late, around the age of three or four years. By that point, most kids have been speaking for years and can use complex sentences.

    So if theory of mind in this sense is required for language, I suppose it would have to be an evolutionary or collective requirement rather than an individual one.

  24. Jess Tauber said,

    January 23, 2010 @ 4:44 pm

    Animal behaviors tend to be extremely ritualized, akin to 'grammaticalization' in languages, and this includes their vocal communications. On the other hand, Eugene Morton's work on his 'Motivation Structure' code, shows that close-contact vocal signals draw from a small set of acoustic/articulatory primitives that are highly conserved phylogenetically.

    In human languages isn't there a tendency for selected grammaticalized morphemes to take on more and more pragmatic function? Though there are only a handful of signal types in an animal's communicative pallette, there is often good variability of individual types, and this might reflect utilization of Morton's or other pragmatically or paralinguistic-like codings.

    Add to the mix the fact that lexical root numbers fall as morphosyntactic synthesis increases (after Fortescue).

    Human beings are known to be neotenic developmentally, so rather than reflecting add-on of previously lacking abilities, our linguistic capacities might in fact be due to destruction of a more automaticized, extreme-pragmatically organized ancestral communicative system, one that had most coding dealing not with externals (lexicon) but with emotion, social ranking, etc.

    My work with ideophones and sound symbolism shows that there is a strong connection with ancestral oral masticatory/deglutitional behavior. Animals haven't generally coapted this into communication, but note that foods are externals. Chimp food calls only minimally differentiate the nature of foods into qualities, last I read.

    Readers might be interested in the following paper that claims language complexity associates with social group size and constituency:


    Also, finally, I've claimed in the past that there were strong parallels between genomic structure and linguistic. Recently I ran across work that shows that genome size is largest (containing much more 'junk', with regulatory functions, origins in repeated sequences and lots of old viruses, which are by nature 'regulatory') in organisms that show more neoteny, wait for environmental factors to mature (pragmatic/context orientation), while those that are in a hurry to mature all at once (including metamorphosis), have narrow ecological niches/specialization, have the smallest genomes (least 'junk').

    I'm guessing that this has relevance to linguistic morphosyntactic type as well, and language origins. Chimp communication would be mostly automaticized/pragmaticized elements (relying more on intonation contours) and only minimally on segment-style formats, to deal with their extremely reduced 'lexicons'.

    [(myl) Do you have any specific experience with chimpanzee "intonation contours", or are you just making a prediction based on a general theory? Would you make the same prediction about gorillas?]

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