Is man the only mammal that acquires the ability to speak? Researchers at Tel Aviv University discovered that bat pups exposed to a certain soundtrack of bat 'conversations' learn to communicate in the 'idiom' they heard in infancy
Research from Tel Aviv University sheds new light on the intriguing question: Is the ability of other mammals (besides humans) to communicate with members of their species innate or learned? The study, conducted in the laboratory of Prof. Yossi Yuval from the Department of Zoology and Sagol School of Neuroscience, revealed three groups of bat pups to bat communication in three different 'dialects', and discovered that each group indeed learns to 'speak' in the dialect that was played to them.
The study was led by research students Yosef Perat and Lindsey Azoulai, and was published on Tuesday (31.10.17) in the journal PLoS Biology.
"Many researchers and thinkers, since the dawn of history, believe that a person is allowed in his ability to learn a language and use it," says Prof. Yuval. "Scientists all over the world are trying to find out how true this assumption is, and to that end they are examining the sounds made by different species of animals. However, only a few studies have so far produced unequivocal results. In our laboratory, we decided to put fruit bat pups to the test."
For the purpose of the study, the puppies were divided into three separate groups - five puppies in each group. During the first year of their lives, the pups in each group were exposed to a different soundtrack - a kind of different dialect - of bat sounds: one group heard a recording of high-frequency sounds, the second group was exposed to the low frequencies, and the third group grew up with a full soundtrack that included all the sounds. The sounds made by the puppies themselves were recorded and decoded every few months.
"We found that the puppies do learn to make the type of sounds they were exposed to," says Prof. Yuval. "It can be said that they learn to 'speak' in the 'dialect' they heard in their infancy. These findings prove that the bats' vocal communication is at least partly acquired, and is learned early in life. In other words: the young bats are not born with their full vocal repertoire, but pick it up from their environment. "
Another significant conclusion from the research is that the puppies learn from the sum of the voices around them, and not necessarily in 'private lessons' from the mother who raises them. In nature, it is about the sounds made by the group, that is, the colony of bats that lives in the cave where they were born. This finding is an innovation in relation to the existing research literature on the subject: the studies, the vast majority of which have focused so far on the chicks of songbirds, have proven that the chicks (as opposed to the bat pups) learn the sounds directly from one of the parents.
"Our research sheds light on the evolutionary origin of the ability to acquire language, and raises questions about the uniqueness of man in this context," concludes Prof. Yuval.
Watch: Voice communication in a bat colony. Credit: Lee Hartan, courtesy of Tel Aviv University.
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