OSAKA -- A Japanese researcher studying a bird common to the country's forests and urban parks has proven for the first time that animals communicate using words and grammar.
Toshitaka Suzuki, a 38-year-old assistant professor at Kyoto University's Hakubi Center for advanced research, first became interested in Japanese tits -- each about 15 centimeters long -- when he was a second-year student at the Faculty of Science at Toho University. In a forest in Karuizawa, Nagano Prefecture, one tit suddenly let out a distinctive "hee-hee" call, and its entire flock took off. This was immediately followed by the appearance of a hawk, the tits' natural enemy, in the sky above.
Convinced that the tits were using different calls, Suzuki began experiments. Since then, he has used the forest as his "laboratory," spending six to eight months a year there for 16 years.
The first thing Suzuki worked on was proving that the birds had "words" as we would understand the term. He experimented with the idea that the "jar-jar" call tits emitted when a snake appeared literally meant "snake." A taxidermy snake was placed above a nest box for observation, and he confirmed that tits made "jar-jar" sounds. The bird did not make the same sound with other taxidermy predators, such as hawks.
Next, he played a recorded "jar-jar" call through a speaker, and the bird looked under the nest box and on the ground as if searching for snakes. However, this alone did not prove "jar-jar" was a word; the bird "may have just had a reflexive tendency to look down," Suzuki said.
Then he came up with another experiment. A stick with a string attached was hung along the trunk of a tree, and a "jar-jar" sound was played through a speaker while the stick was pulled up like a snake climbing the trunk. In most cases, the tits approached the stick when the "jar-jar" sound was played, and appeared to check it. With other calls, this behavior was almost never observed. Therefore, he reasoned that when they heard "jar-jar," the tits assumed a snake was nearby and mistook the stick for the reptile.
The results were published in the Proceedings of the National Academy of Sciences of the United States of America in 2018 (https://www.pnas.org/doi/10.1073/pnas.1718884115). It was the first an animal had been shown to use words.
Suzuki has also researched "grammar." His focus was on the "'pee-tsupi' (be alert) 'ji-ji-ji-ji' (gather around)" sounds made by tits when chasing off natural enemies. When they hear this, the tits gather near their natural enemies and threaten them, while keeping an eye on their surroundings. However, the birds did not look alert or gather when the word order was swapped to "ji-ji-ji-ji pee-tsupi." In other words, he thought it was possible that they recognized the meaning by word order, or grammar.
There have been numerous reports of animals "possibly having language," but it had not been proven scientifically. Suzuki said, "Research on animal language has not progressed well because of the assumption that humans are absolutely different from other animals. I hope that my method will be used as a reference for further research on other animals."
His future goal is to create a field he dubs "animal linguistics" to deepen people's understanding of animal communication.
(Japanese original by Kouki Matsumoto, Osaka Science & Environment News Department)