Commentary on "The Mystery of Language Evolution"

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This is a guest post by Herbert Terrace and Michael Studdert-Kennedy, in the form of a response to Marc Hauser, Charles Yang, Robert Berwick, Ian Tattersall, Michael Ryan, Jeffrey Watumull, Noam Chomsky, and Richard C. Lewontin, "The Mystery of Language Evolution", Frontiers of Psychology 2014.

Herb Terrace explains:

At Charles Yang's suggestion, Michael Studdert-Kennedy and I would like to offer a commentary to Language Log in response to an article that appeared in 2014 in Frontiers of Psychology […]. That commentary was peremptorily rejected by Frontiers without explanation.

"Each of us learns his language from other people, through the observable mouthing of words under conspicuously intersubjective circumstances." (Quine, 1960)

In a recent article on the evolution of language, Hauser et al. (2014) concluded that, despite "an explosion of research on this problem," there has been a "poverty" of viable ideas and that, until further evidence is available, our “ . . . understanding of language evolution will remain one of the great mysteries of our species" (p. 1).

The evidence that Hauser et al. (2014) considered is limited, however, reflecting a syntactocentric view of generative linguistics and a failure to consider recent discoveries about the social and cognitive development of a human infant during her first year of life. The latter limitation is a direct consequence of the former.

We do not question the value of the syntactocentric model for descriptive linguistics. But for evolution, it provides no path along which words, the conceptual-intentional primitives of language, which are preconditions for syntax and no less uniquely human, might have developed. Nor does the circular form of their model (Hauser et al., 2002, Figure 2) acknowledge the generally accepted hierarchical structure of language (e.g., Jakobson, 1970) in which syntax must have evolved from semantic and logical relations among words.

Here we call attention to the imperative and declarative functions of words and to the fact that “words” trained in experiments on animal language are strictly imperative. An imperative utterance is uni-directional, its purpose to motivate another being to act, e.g., to provide food, to hug, move out of my territory, etc. In principle, vending machines can be designed to satisfy imperatives. By contrast, declarative communication, implying conversation between a speaker and a listener, was a fundamental step in the evolution of language.

Hauser et al. (2014) seem to be aware that no animal has been trained to communicate declaratively. Discussing Nim Chimpsky, “the chimpanzee that produced the only corpus of data in all animal language studies", they remark that he "produced signs considerably below the expected degree of combinatorial diversity seen in two-year old children…with no understanding of syntactic structure or semantic interpretation". But that observation points to a contradiction in the syntactocentric model of language, a model supposedly uncontaminated by social factors. Any discussion of semantics implies social engagement between a speaker and a listener, in particular, conversation. Indeed, without conversation a child would never learn any words at all, let alone a language.

We are hardly the first to observe that words must have the evolved before syntax (e.g., Bickerton, 1981, 2014; Deacon, 1997; Donald, 1991; Jackendoff, 2002). Nor are we the first to observe the importance of shared reference in the emergence of a child’s first words (Bloom, 2000). We simply call attention to recent research on pre-verbal social mechanisms that contribute to a child’s understanding of a speaker’s referential intent. Hauser et al. (2014) endorse ontogeny as an "important source of evidence for the biological basis of language" (p. 3), but confine their examples to grammar.

Before the recent spurt of research on the social development of infants, little attention was paid to the psychological implications of major anatomical differences between humans and chimpanzees or to the resulting differences in the social evolution of various members of Homo that intervened. A common theme of this research is the fragility of the human infant at birth, forcing extensive postnatal dependency. About 6 mya, long before the size of the Homo brain began to grow, bipedalism was the most important feature distinguishing our ancestors from chimpanzees. One consequence of bipedalism was a decrease in the size of the pelvis, setting a limit on the size of the head that could pass through the birth canal. A human infant’s brain at birth is only ~25% of its adult size; a chimpanzee’s, ~40% (Rosenberg & Trevathan, 1996). Another anatomical change was loss of fur (Wheeler, 1985). Without fur to cling to, a human infant had to be cradled in her mother’s arms where her eyes could readily meet her mother’s.

An infant experiences two significant modes of interaction during her first year. During a dyadic (intersubjective) stage (2-6 months), she is cradled and engages in bouts of face-to-face contact with her mother. These provide opportunities for the infant to detect discrepancies between her and her mother’s emotional states, e.g., when she is happy (or sad) and her mother is not. Beebe (2014), Beebe et al. (2010), Lyons-Ruth (1999), Stern (1985) and Trevarthen and Aitken (2001) hypothesize that infants develop a sense of another’s emotional state from these discrepancies.

During a triadic stage (joint attention), the infant engages in mutual eye gaze with her mother toward particular objects or events and shares attention to them (Scaife & Bruner, 1975; Tomasello, 1995). Behavioral markers of joint attention include the infant’s efforts to direct her mother’s attention by repeatedly shifting her gaze between her mother and an object, and by smiling and cooing when she achieves her goal (Carpenter & Kristen, 2012). Because joint attention combines the mother’s and the infant’s attention to particular objects or events, it allows the infant to infer referential intent from another’s utterances and thereby serves as a foundation for declarative vocabulary (Brooks & Meltzoff, 2008). Evolutionarily, this capacity must have emerged before words.

Although there are sporadic examples of mutual eye gaze in nonhuman primates (Ferrari et al., 2009), it is not sustained with the intensity of mother–infant gaze (Suomi, 2005). Psychologists believe that nonhuman primates use facial and bodily expression to interpret another’s behavior, while infants use them to apprehend another’s mental state (e.g., Tomasello, 2010). Evidence for the perception of other minds in non-human primates does not support the idea that they can coordinate their perceptions of each other’s mind. That is a key difference in the social psychology of human and non-human primates (Terrace, 2013).

Hauser et al. (2014) disregard intersubjectivity and joint attention because the syntactocentric model eschews social factors. But that model doesn’t determine what is and is not relevant for theories of language evolution. There is wide consensus that social factors, in particular those between infant and mother during the infant’s first year precipitate the infant’s first words. As noted by (Hobson, 2002),

Those psychologists who believe that humankind became unique by acquiring language are not altogether wrong. But they are not altogether right, either. Before language, there was something else more basic, in a way more primitive, and with unequalled power in its formative potential that propelled us into language. Something that could evolve in tiny steps, but suddenly gave rise to the thinking processes that revolutionized mental life…That something else was social engagement with each other. The links that can join one person's mind with the mind of someone else— especially, to begin with, emotional links— are the very links that draw us into thought.

Without those links we would have no words, without words, no syntax.


Beebe, B. (2014). My journey in infant research and psychoanalysis: Microanalysis, a social microscope. Psychoanalytic Psychology, 31(1), 4. doi: 10.1037/a0035575

Beebe, B., Jaffe, J., Markese, S., Buck, K. A., Chen, H., Cohen, P., Bahrick, L., Andrew, H., & Feldstein, S. (2010). The origins of 12-month attachment: A microanalysis pf 4-month mother-infant interaction. London, UK: Routledge.

Bickerton, D. (1981). The Roots of Language. Ann Arbor, MIchigan: Karoma Publishers.

Bickerton, D. (2014). More Than Nature Needs: Language, Mind, and Evolution. Cambridge, MA: Harvard University Press.

Bloom, P. (2000). How Children Learn The Meanings of Words. Cambridge: The MIT Press.

Brooks, R., & Meltzoff, A. (2008). Infant gaze following and pointing predict accelerated vocabulary growth through two years of age: a longitudinal, growth curve modeling study. Journal of Child Language, 35(01). doi:10.1017/S030500090700829X

Carpenter, M., & Kristen, L. (2012). Joint Attention, Communication, and Knowing Together in Infancy Joint Attention. Cambridge MA: MIT Press.

Deacon, T. W. (1997). The Symbolic Species: The co-evolution of language and the brain. New York: Norton Paperback.

Donald, M. (1991). Origins of the modern mind. Cambridge, MA: Harvard University Press.

Ferrari, P., Paukner, A., Ionica, C., & Suomi, S. (2009). Reciprocal face-to-face communication between rhesus macaque mothers and their newborn infants. Current Biology, 19, 1768-1772.

Hauser, M., Chomsky, N., & Fitch, W. T. (2002). The faculty of language: What is it, who has it, and how did it evolve? Science, 298, 1569-1579.

Hauser, M., Yang, C., Berwick, R., Tattersall, I., Ryan, M., Watumull, J., Chomsky, N., & Lewontin, R. (2014). The mystery of language evolution. Front Psychol, 5, 1-12.

Hobson, P. (2002). The Cradle of Thought: Exploring the Origins of Thinking. London: Macmillan.

Jackendoff, R. (2002). Foundations of language: Brain, meaning, grammar, evolution. Oxford University Press, USA.

Jakobson, R. (1970). Linguistics: Main Trends of Research in the Social and Human Sciences (pp. 419-466). Paris/The Hague: UNESCO/Mouton.

Lyons-Ruth, K. (1999). The Two-Person Unconscious: Intersubjective Dialogue, Enactive Relational Representation, and the Emergence of New Forms of Relational Organization. Psychoanalytic Inquiry, 19, 576-617.

Quine, W. V. O. (1960). Word and Object. Cambridge, MA: MIT Press.

Rosenberg, K. R., & Trevathan, W. R. (1996). Bipedalism and human birth: The obstetrical dilemma revisited. Evolutionary Anthropology, 4, 161-168.

Scaife, M., & Bruner, J. (1975). The capacity for joint visual attention in the infant. Nature, 253, 265-266.

Stern, D. N. (1985). The interpersonal world of the infant. New York: Basic Books.

Suomi, S. (2005). Mother-infant attachment, peer relationships, and the development of social networks in rhesus monkeys. Human Development, 48, 67-79.

Terrace, H. (2013). Becoming Human: Why Two Minds are Better than One. Agency and joint attention (pp. 11-48): Oxford University Press.

Tomasello, M. (1995). Joint attention as social cognition. Joint attention: Its origins and role in development, 103-130.

Tomasello, M. (2010). Origins of human communication. Cambridge, Mass.; London: MIT Press.

Trevarthen, C., & Aitken, K. J. (2001). Infant intersubjectivity: Research, theory, clinical applications. Journal of Child Psychology and Psychiatry, 42(1), 3- 48.

Wheeler, P. (1985). The loss of functional body hair in man: the influence of thermal environment, body form and bipedality. Journal of Human Evolution, 14, 23-28.


Preparation of this manuscript was supported by NIH grant MH081153-06.

We thank Beatrice Beebe, Katherine Nelson and Robert Remez for their helpful comments.

Above is a guest post by Herbert Terrace and Michael Studdert-Kennedy.


  1. DWalker said,

    November 3, 2015 @ 2:13 pm


  2. Edmund Blair Bolles said,

    November 3, 2015 @ 5:08 pm

    I'm used to being ignored and try not to take it personally, but in this case I feel it would have been reasonable to mention my book: Babel's Dawn, a natural history of the origins of speech. I discuss at length the role of hairlessness, single word stage, triadic relations, etc. I am in full agreement with this post, and my book fleshes out its thinking considerably.

  3. J. W. Brewer said,

    November 3, 2015 @ 5:46 pm

    Just as the geographical range of hairless primates is only confined to the tropics until they figure out how to wear clothing (or "evolve" the capacity for clothing-wearing), hairless primates only need to cradle their babies in their arms until they evolve the technology for toting their infants around while keeping their hands free. Here's a scientific Just So Story claiming that that technology popped up so early as to be relevant to brain size in modern humans:

    There is as I understand it considerable variation among human societies at present in how much time infants typically spend in slings-or-the-equivalent (and if so in what physical configuration) which in turn can affect what percentage of waking hours at a given early age is typically spent face-to-face with an adult rather than carried-on-back. I would be curious to know how much cross-cultural fieldwork has gone into the prior publications about typical human infant development (dyadic to triadic etc and how it relates to language acquisition) cited above, or whether this is one of those situations where WEIRD babies whose parents happen to live conveniently close to university psychology departments are presumed representative of the species as a whole.

  4. Jeff W said,

    November 3, 2015 @ 6:19 pm

    pre-verbal social mechanisms…“That something else was social engagement with each other”

    Not being a linguist, perhaps I don’t get the frame of the debate, although I get some of what is being said here.

    The way I view it is social animals are particularly attuned, for evolutionary reasons, to who is acting with respect to whom—A is grooming B. C is acting dominant with respect to D, E is trying to get the attention of F and so on. There is a “syntax”—an arrangement or structure—to those actors and that behavior—A grooming B—is a different arrangement than, say, B grooming A, although all the elements of action (A, B, and grooming) remain identical. If a species, say, humans, starts using words, to refer to the actors and their actions, which is a major evolutionary step, it doesn’t seem all that surprising (or that much of a mystery) to me to have something like syntax evolve, probably almost simultaneously with words, to reflect those differences that occur in the real world, differences that matter to social animals.

    I’m not so sure I get the whole “words must have the evolved before syntax” frame. That, to me, is like saying “cars must have evolved before traffic rules”—they did, strictly speaking, but that doesn’t mean that before cars, probably for millennia, people crashed into each other all the time on roads or didn’t yield to each other, in some way, at intersections. The behavior that traffic rules deal with has its precursors in “pre-car” behavior; at least some of the behavior that syntax deals with—the structure/arrangement of elements (words)—has its precursors in “pre-word” behavior.

  5. bks said,

    November 3, 2015 @ 8:55 pm

    Very little here seems susceptible to either reproducibility or replicability though linguists may see that differently. I remember a discussion (among molecular biologists) about FOXP2 (the grammar gene) circa 1994. There doesn't seem to have been a great deal of progress.

    [(myl) I hope that your italics are an indication of sarcasm. See "The hunt for the hat gene", 11/15/2009, for an explanation of why.]

  6. Sarah Creel said,

    November 3, 2015 @ 10:15 pm

    Something actually got rejected from Frontiers?

  7. Sarah Creel said,

    November 3, 2015 @ 11:23 pm

    (No disrespect to the authors, who have written a nice piece, rather to Frontiers' publishing model.)

  8. The origins of language: AkhaṇḍakhaṇḍanamThe Indian Philosophy Blog | The Indian Philosophy Blog said,

    November 16, 2015 @ 3:44 pm

    […] title refers to a recent post on Language Log by Herb Terrace, which is a response to an article by Hauser et al. that appeared […]

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