Letter | Published:

Recursive syntactic pattern learning by songbirds


Humans regularly produce new utterances that are understood by other members of the same language community1. Linguistic theories account for this ability through the use of syntactic rules (or generative grammars) that describe the acceptable structure of utterances2. The recursive, hierarchical embedding of language units (for example, words or phrases within shorter sentences) that is part of the ability to construct new utterances minimally requires a ‘context-free’ grammar2,3 that is more complex than the ‘finite-state’ grammars thought sufficient to specify the structure of all non-human communication signals. Recent hypotheses make the central claim that the capacity for syntactic recursion forms the computational core of a uniquely human language faculty4,5. Here we show that European starlings (Sturnus vulgaris) accurately recognize acoustic patterns defined by a recursive, self-embedding, context-free grammar. They are also able to classify new patterns defined by the grammar and reliably exclude agrammatical patterns. Thus, the capacity to classify sequences from recursive, centre-embedded grammars is not uniquely human. This finding opens a new range of complex syntactic processing mechanisms to physiological investigation.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Hockett, C. F. The origin of speech. Sci. Am. 203, 89–96 (1960)

  2. 2

    Chomsky, N. Syntactic Structures (Mouton, The Hague, 1957)

  3. 3

    Hopcroft, J. & Ullman, J. Introduction to Automata Theory, Languages, and Computation (Addison-Wesley, Reading, Massachusetts, 1979)

  4. 4

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

  5. 5

    Fitch, W. T., Hauser, M. D. & Chomsky, N. The evolution of the language faculty: clarifications and implications. Cognition 97, 179–210 (2005)

  6. 6

    Eens, M. Understanding the complex song of the European starling: An integrated approach. Adv. Study Behav. 26, 355–434 (1997)

  7. 7

    Gentner, T. Q. & Hulse, S. H. Perceptual mechanisms for individual vocal recognition in European starlings, Sturnus vulgaris. Anim. Behav. 56, 579–594 (1998)

  8. 8

    Gentner, T. Q. & Hulse, S. H. Perceptual classification based on the component structure of song in European starlings. J. Acoust. Soc. Am. 107, 3369–3381 (2000)

  9. 9

    Gentner, T. Q. & Margoliash, D. Neuronal populations and single cells representing learned auditory objects. Nature 424, 669–674 (2003)

  10. 10

    Hauser, M. D., Newport, E. L. & Aslin, R. N. Segmentation of the speech stream in a non-human primate: statistical learning in cotton-top tamarins. Cognition 78, B53–B64 (2001)

  11. 11

    Hauser, M. D., Weiss, D. & Marcus, G. Rule learning by cotton-top tamarins. Cognition 86, B15–B22 (2002)

  12. 12

    Fitch, W. T. & Hauser, M. D. Computational constraints on syntactic processing in a nonhuman primate. Science 303, 377–380 (2004)

  13. 13

    Pinker, S. & Jackendoff, R. The faculty of language: what's special about it? Cognition 95, 201–236 (2005)

Download references


We thank T. Brawn for help in conducting some of these experiments, and A. Henly, P. Visser and L. Kay for comments on an earlier draft. This research was supported by an NIH grant to D.M.

Author information

Correspondence to Timothy Q. Gentner.

Ethics declarations

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Supplementary information

Supplementary Note

This file contains the Supplementary Methods, Supplementary Discussion, Supplementary Tables and Supplementary Figures. (PDF 1351 kb)

Rights and permissions

Reprints and Permissions

About this article

Further reading

Figure 1: Grammatical forms.
Figure 2: Classification of grammatical pattern stimuli.
Figure 3: Generalization to new FSG and CFG sequences.
Figure 4: Agrammatical controls for alternative strategies.


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.