Syntax has long been a pillar of human language, but new research appearing in the latest issue of the journal Nature Communications suggests that the ability to combine different words and phrases to generate novel meanings may not be an ability uniquely possessed by humans.
A recent study by researchers from Japan, Germany and Sweden challenges this view, demonstrating that the Japanese great tit, known for its diverse vocal repertoire, have evolved syntax. This small bird species experiences a number of threats, and in response to predators, they give a variety of different calls. These calls can be used either alone or in combination with other calls. Using playback experiments, Dr. Suzuki and colleagues could demonstrate that ABC calls signifies “scan for danger”, for example when encountering a perched predator, whereas D calls signify “come here”, for example when discovering a new food source, or to recruit the partner to their nest box. Tits often combine these two calls into ABC-D calls such as when approaching and deterring predators. When these two calls are played together in the naturally occurring order (ABC-D), then birds both approach and scan for danger. However, when the call ordering is artificially reversed (D-ABC), birds do not respond.
‘This study demonstrates that syntax is not unique to human language, but also evolved independently in birds. Understanding why syntax has evolved in tits can give insights into its evolution in humans’, says David Wheatcroft, post doc at the Department of Ecology and Genetics at Uppsala University and co-author of the study.
Japanese great tits use different calls to coordinate a variety of social interactions, each of which requires specific behavioural responses. Syntax provides rules for combining the elements from a small vocabulary to generate novel meanings that can be readily recognized. These rules may be an adaptation to social and behavioural complexity in communication systems, such as in human language.