“As a feature of life on earth, language is one of science’s great remaining mysteries” 1:1. From early childhood on, human children produce a rich array of sounds, a manifestation of their potent urge to engage in communicative activities, obtain objects, and affect the thinking and behaviour of other people. Speech consists of over 100 acoustically unique phones, commonly combined into rapid sequences, which serve as the main carriers of meaning. These two characteristics—a rich acoustic portfolio and the predisposition to combine basic units into more complex acoustic strings—appear to be unique to the human species, and call for an evolutionary investigation 1,2. However, only recently has the topic of language origins returned to respectability after a long exile, including scholars from a wide variety of scientific disciplines such as Anthropology, Comparative Psychology, Computational Biology, Primatology, Linguistics, and Neuroscience for a recent overview see 3. Additionally, scholars have been focusing more and more on different components of language, for each of which a different evolutionary story is appropriate 4. A crucial component are gestures, which are used to communicate alongside, or instead of, speaking and are integral parts of speech and thinking in language 3. Moreover, human children go through a gesture phase before they use their first spoken words to interact and direct the attention of their caretakers 5. It thus has been hypothesized that this brief period in human ontogeny recapitulates phylogeny, with gestures being the launching pad out of which human speech may have blossomed e.g. 6,7.
This so called gesture-first hypothesis especially inspired comparative researchers to search for evolutionary precursors to human language in nonhuman primate gesturing 7. Here, I will present an overview of the state of the art and focus in detail on recent findings concerning similarities and differences in gestural abilities of great apes and humans. In addition, I will introduce recent findings 8 on gestural abilities of the corvid family, ravens (Corvus corax), to evaluate the question whether comparable communicative behaviours reflect comparable cognitive abilities.
1 Knight, C., Studdert-Kennedy, M. & Hurford, J. R. in The Evolutionary Emergence of Language: Social Function and the Origins of Linguistic Form (eds Chris Knight, Michael Studdert-Kennedy, & James R. Hurford) 1-15 (Cambridge University Press, 2000).
2 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, 1568-1579 (2002).
3 McNeill, D. How Language Began. Gesture and Speech in Human Evolution. 278 (Cambridge University Press, 2012).
4 Hurford, J. R. Recent developments in the evolution of language. Cognitive Systems 7, 23-32 (2006).
5 Bates, E., Benigni, L., Bretherton, I., Camaioni, L. & Volterra, V. The Emergence of Symbols: Cognition and Communication in Infancy. (Academic Press, 1979).
6 Hewes, G. W. Primate communication and the gestural origin of language. Current Anthropology 12, 5-24 (1973).
7 Tomasello, M. Origins of Human Communications. 268 (MIT Press, 2008).
8 Pika, S. & Bugnyar, T. The use of referential gestures in ravens (Corvus corax) in the wild. Nature Communications 2, 1-5, doi:10.1038/ncomms1567 (2011).