Emotional signals of a false vampire bat

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Bats are able to detect and respond to emotion in a similar way to humans, finds new research published in Frontiers in Zoology this week. Using recorded acoustic calls, researchers showed that the false vampire bats showed a different response to ‘aggressive’ compared to ‘response’ calls.

Hanna Kastein from the University of Veterinary Medicine in Hannover and her team of colleagues investigated the bats responses to calls of different intensity using playback experiments. By observing whether or not the bats were distracted from a feeder provided, researchers could establish their reaction to the call. While both ‘aggressive’ and ‘response’ calls initially evoked a reaction from the bats, over time, the bats stopped reacting to the ‘response’ calls as they decreased in intensity, although the same was not true for the ‘aggressive calls’. Slowed down examples of the call recordings used in these experiments are available to listen to online.
Credit Aditya Joshi wikimedia

From this experiment, the authors infer that the bats are able to judge the calls on the basis of emotional relevance and react differentially to each call type. They showed that the bats used the call structure, and prior experience, to asses calls and react appropriately.

Bats are only very distantly related to humans, meaning that any shared trait between bats and humans is likely to also be shared across all other mammals, and thus derived from an ancient common ancestor. These findings suggest that all mammals may have the ability to perceive emotions from acoustic signals, in a similar way to humans.

Senior author Sabine Schmidt said: “Showing that these mechanisms exist in bats suggests that this might be common across the mammals. These might not be the precursors of speech as we know it, they probably have more in common with para-linguistic communication, like human laughter, or a baby’s cries – sounds which encode important emotional information, but don’t have any actual speech content.”