SCIENCE AT THE SHINE DOME canberra 2 - 4 may 2007
Symposium: Development and evolution of higher cognition in animals
Friday, 4 May 2007
Professor Christopher Evans
Director, Centre for the Integrative Study of Animal Behaviour, Macquarie University, Sydney
Chris Evans is Director of the Centre for the Integrative Study of Animal Behaviour at Macquarie University. He received his undergraduate degree in Zoology from the University of Cambridge and his doctorate in Experimental Psychology (Animal Behaviour) from Washington University. Chris has been studying visual and acoustic communication for over 20 years. This work has involved a range of systems, including birds, lizards, fish, marsupials and monkeys, but with a consistent focus on the mechanisms responsible for functionally critical responses. In particular, the exploration of referential signalling in birds has combined analyses of cognitive processes - revealing striking parallels with language - with work on variation in reproductive success providing insights into the evolution of complex vocal communication.
Communication and cognition in birds
| Many species produce calls in response to critical external events, such the approach of predators or the discovery of food. These ‘referential signals’ are remarkable. The information encoded can be highly specific, revealing cognitive mechanisms like those that underpin language and supporting Darwin’s original argument for continuity between human and non-human systems. Perhaps surprisingly, much of the experimental evidence comes from studies of social birds, rather than primates or other groups phylogenetically closer to humans. Language-like signalling is hence more taxonomically widespread than has previously been thought, suggesting that it may be the product of particular patterns of relatedness within stable social groups. Studies of the costs and benefits of calling are beginning to reveal the selective factors responsible for the evolution of these systems. Aerial alarms are only produced when appropriate receivers are present, have structural attributes that make them ‘stealthy’, and are flexibly modified during an encounter with a predator to further manage risk. Males alarm call at rates that correlate closely with their recent mating frequency, suggesting judicious investment in descendant kin and/or risk-taking as a female mate choice cue. Similar trade-offs are apparent in the production of food calls. These are used deceptively to lure females close enough for courtship, but hens can discriminate the calls of different males and rapidly cease responding to unreliable callers. Scepticism by intended receivers is hence an important social constraint. These results illustrate the benefits of an integrative approach and encourage further comparative study. |
