Egyptian fruit bats roost upside-down at the entrance to a cave in central Israel..
(photo credit: ERAN AMICHAI)
Humans are not the only mammals to speak specific “dialects” – so do bats, according to the “language” used in their own colonies. This was discovered by Tel Aviv University researchers and just published in the open-access journal PLOS Biology.
Young bats from the age of six months adopt a specific “dialect” spoken by their own colonies, even when this dialect differs from the bat “mother tongue,” discovered Dr. Yossi Yovel and his students Yosef Prat and Lindsay Azoulay at TAU’s department of zoology. By offering insight into the evolutionary origins of language-acquisition skills, the study calls into question the uniqueness of the skill in humans.
For the research, the team raised 14 bat pups with their mothers in three different colonies.
In these laboratory colonies, the scientists used electronic speakers to issue three specific subsets of natural bat vocalizations. The researchers exposed the young bats to the recordings over a period of one year, until they reached adulthood.
Although the young bats were exposed to their mothers’ “normal” dialect and could communicate with their mothers, each group developed a dialect resembling the one they were exposed to through the recordings.
“The difference between the vocalizations of the mother bat and those of the colony are akin to a London accent and, say, a Scottish accent,” Yovel explained. “The pups heard their mothers’ ‘London’ dialect, but also heard the ‘Scottish’ dialect mimicked by many dozens of ‘Scottish’ bats.
The pups eventually adopted a dialect that was more similar to the local ‘Scottish’ dialect than to the ‘London’ accent of their mothers.”
The ability to learn vocalizations from others is extremely important for human speech acquisition, but it’s believed to be rare among animals,” Yovel continued. “Researchers have believed that this is what makes human language unique.”
Songbirds are the most common animal models for “vocal learning,” and they learn songs from specific tutors.
These studies typically indicate that a bird learns to sing from one parent. But the TAU study shows that bats listen and learn from an entire colony of several hundred bats, not just from their parents. “In other words,” concluded Yovel, “young bats pick up the dialect vocalized by their surrounding roost-mates.”
The researchers will now examine how the acquisition of a new dialect influences the ability of bats to integrate into foreign colonies. “Will they adopt the local dialect or will they be rejected by the group? Or maybe the local colony will change its dialect to adopt that of our bats,” Yovel speculated.
“There are many interesting avenues yet to explore.”
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