Birds have evolved syntax and communicate according to various calls using specific rules just like humans, do, say scientists from Sweden, Switzerland and Japan. After extensively studying Japanese great tits, also known as Oriental tits, they found that birds communicated specific messages and engage in complex interactions, just like we do.
The researchers wrote in the prestigious journal Nature Communications (citation below) that language is one of the defining traits of human beings – it enables us to generate virtually unlimited meanings from a finite number of sounds (phonetic elements).
Using syntactic rules, we are able to combine words to create phrases and sentences, and thus attribute meaning to an endless number of things and actions.
‘Birds have evolved syntax’ means that if they sequence their sounds in a certain order, according to a rule, they communicate one thing. If those same sounds are sequenced differently, the meaning is either lost or changed. In other words ‘Bird-speak has grammar’. (Image: ivin-vv.livejournal.com)
Syntax is the arrangement of words and phrases to create well-formed sentences in a language.
Cambridge Dictionaries online defines syntax as:
“The grammatical arrangement of words in a sentence.”
Studies on communications systems suggest that birds and non-human primates (chimps, gorillas, orangutans) have also evolved the ability to ascribe meaning to arbitrary vocal elements. However, the evolution of syntax has always been considered a unique characteristic of human language, that is, until now.
Add mating call to warning signal to get ‘flock together’
Evolutionary biologists at the University of Zurich in Switzerland, Uppsala University in Sweden, and the Graduate University for Advanced Studies in Japan, suggest that syntax is not unique to humans.
(1) ABC call is composed of single A, B and C notes. (2) D call is composed of seven to ten D notes. (3) ABC+D call is the combination of ABC and D calls. (4) D+ABC call is ABC and D calls in reverse order. When an ABD+D recording was played, the birds flocked together most of the time. When it was played in reverse – D+ABC, they ignored it most of the time. (Image: Nature Communications).
They say they have demonstrated, for the first time, that Japanese great tits (Parus minor) have developed syntactic rules. In other words, those birds have developed grammar.
Japanese great tits are well known for their large vocal repertoire. The research team discovered that the birds use a variety of calls and combination of calls to communicate with each other in specific situations.
How they put their vocalizations and call combinations together alters what they are trying to say to one another.
If they combine the sounds of, for example ‘ABC calls’, they are saying ‘watch out!’
If a predator such as a sparrohawk is nearby, the great tits use the ‘watch out’ combination. Contrastingly, ‘D calls’ mean ‘come over here’ – it is a call that birds use when they have discovered a new source of food or when they want their partner to come to the nest.
Changing call order alters or cancels meaning
Japanese great tits combine these two calls into ABC-D calls when, for example, they encounter predators and join forces to either scare them off or deter them.
When they hear a recording of these calls played in the natural order of ABC-D, the birds are clearly alarmed and flock together.
On the other hand, however, when the call ordering was artificially reversed by the researchers – to D-ABC – they did not respond.
Combining vocabulary to generate meaning
The scientists said that birds are able to string words together and generate several different meanings. They concluded that syntax is not unique to human language – it has also evolved independently in birds.
Dr. Michael Griesser, Head of Social Bird Group at the Anthropological Institute and Museum, University of Zurich, said regarding his and his team’s findings:
“The results lead to a better understanding of the underlying factors in the evolution of syntax. Because the tits combine different calls, they are able to create new meaning with their limited vocabulary. That allows them to trigger different behavioral reactions and coordinate complex social interactions.”
He thinks these factors could well have contributed to the development of language in human beings.
Citation: “Experimental evidence for compositional syntax in bird calls,” Toshitaka N. Suzuki, David Wheatcroft & Michael Griesser. Nature Communications 7, Article number: 10986. 8 March, 2016. DOI: 10.1038/ncomms10986.
Video – A Japanese great tit collecting moss for its nest