Tuesday, November 7, 2017

Bat Talk

This Blog Post by
Emily Lau, Hunter College

Photo: Egyptian Fruit Bat; Source: Fethiye Times
As I was reading the science section of the New York Times, I came across an interesting and linguistically relevant article reporting on the study of vocal learning in bats[1]. The writer, Steph Yin, begins this piece with a personal anecdote, highlighting how she adopted English in preschool rather quickly despite growing up in a household that only spoke Mandarin. Yin proceeds to tie this in with a recent study on fruit bats, which revealed that young bat pups vocalized in the same manner as the whole group, even if this vocalization was different than their mother’s[2].

 The scientific paper (published in PLOS Biology) details the methods and results of this experiment. In this study, captured pregnant Egyptian fruit bats gave birth in different chambers. After 14 weeks (when bat pups normally leave their mother in the wild, indicating the end of any natural critical learning period), the mother bat was removed and the researchers played different sounds to the developing bats. 

They found that the bats exposed to higher pitches began to emit high pitch calls and that the bats exposed to lower pitches emitted lower pitch calls. To put this in context, Dr. Yovel, a scientist in this study who featured in the NY Times piece, stated that these differences in pitch are comparable to different accents (like Texan and New England).

Photo: Accents; Source: Thrillist

These researchers would like to further their work by understanding how this learned change in pitch, or dialect, would affect the bat’s social behaviors. I think it would be interesting to look at twin studies of these bats as well. Given that these two twins are genetically identical, a bat twin study could further our knowledge on nature vs. nurture (if behaviors are inherited or acquired).

This phenomenon is called “vocal learning” and explains how organisms can acquire and produce sound. In humans (especially infants and toddlers), this ability is extremely important in language and social development. Previously, animal behaviorists determined that vocal learning can be found in animals such as hummingbirds and elephants. This study is groundbreaking because it further asserts that vocal learning exists in animals other than humans, therefore refuting the “human exceptionalism belief”, or the belief that humans are distinctly different from all other animals.

Photo: Hummingbird; Source: Phenomena National Geographic

Future vocal learning research in all branches of the animal kingdom will reveal whether human vocal learning is an ancestral or independently evolved behavior. In the future, if we do discover vocal learning in a diverse range of animals, the belief of human exceptionalism would most likely crumble.

Given these results, do you think humans are unique in their language acquisition skills? 
Do you think a bat’s dialect would have an impact on its social behaviors? 
Are there more animals that are capable of vocal learning? 
And finally: could animals potentially have language?

[2] Crowd vocal learning induces vocal dialects in bats: Playback of conspecific shapes fundamental frequency usage by pups: http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2002556

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