Birds understand grammar?

Mico Tatalovic
University of Oxford

Recent research published in Nature suggests humans may not be alone when it comes to using complex grammar rules in language [1]. What was once thought to be a feature unique to humans has now been found in the singing of a small bird: the European starling.

European starlings have been trained to distinguish between different sequences of starling-generated sounds based on the grammatical rules of recursion. The trained birds were then able to distinguish between different sounds generated following the same grammatical rules. Gentner et al. argue that this demonstrates that the starlings learned to distinguish the two distinct grammatical forms [1]. One of these forms, recursive grammar, has been considered the main and perhaps only feature distinguishing the human language from animal languages [2]. Many consider language to be a prerequisite for the development of self-consciousness.

Recursion or self-embedding involves the formation of long sentences using the same general rule. For instance: ‘birds comprehend grammar’ could be embedded into a frame of ‘X knows Y’ such as ‘Gentner says birds comprehend grammar’, and this can be further embedded to give ‘I say Gentner says birds comprehend grammar’ [2]. So far, researchers have found no evidence of comprehension of this grammatical form in primates. Primates, the closest human evolutionary relatives, are often the first to be researched when it comes to looking for human-specific behaviour such as language or complex tool use. However, this example reminds us that we should not exclude other animal groups, as an a priori assumption, as candidates for higher cognitive abilities.

Some researchers suggest that birds might be just as, if not more, intelligent than primates. The current research effort with New Caledonian Crows is unravelling the roles of intelligence and cultural transmission of tool use in these birds [5]. They have been shown to carefully choose their tools, produce them out of natural materials, like Pandanus leaves, and even produce hooks out of straight wire in order to get food [5]. The hook use outperforms two-year-old humans, who do not yet understand how hooks operate [5]. Chimpanzees also fail to understand principles of using hooks to acquire food.

Behaviours such as complex language and tool use may not be as specific to humans as we once thought. Further research into how and why these behaviours evolve in the wild may help us learn more about our own evolution and place in the natural world.

Listen to starling songs at: http://ucsdnews.ucsd.edu/newsrel/soc/gentner_starling06.asp

Watch videos of Caledonian crows using and making tools at:
http://users.ox.ac.uk/~kgroup/tools/tools_main.shtml

References:

[1] Gentner T. Q. et al, Recursive syntactic pattern learning by songbirds, Nature, 2006, 440, 1204-1207, http://www.nature.com/nature/journal/v440/n7088/full/nature04675.html

[2] Marcus G.F.‘Language: startling starlings’ Nature, 2006, 440, 1117-1118, http://www.nature.com/nature/journal/v440/n7088/full/4401117a.html

[3] Kiderra I. “The birds and the B’s challenging Chomsky, Starlings learn ‘human-only’ syntax patterns’ UCDS news online, 2006 http://ucsdnews.ucsd.edu/newsrel/soc/gentner_starling06.asp

[4] Marler, “Social Cognition: Are Primates Smarter Than Birds?” Vol. 13. Ed. Nolan and Ketterson. Plenum Press, New York. 1996

[5] Behavioural Ecology Research Group at the University of Oxford: http://users.ox.ac.uk/~kgroup/tools/tools_main.shtml

Image courtesy of wdfw.wa.gov