If you're like us, you've been guilty of projecting human emotions on animals. The cat is embarrassed that she fell off the dresser! Those two elephants at the zoo are in love! But animals aren't human, so we don't have any way of knowing how they're feeling — right? Not so fast. It turns out that humans are remarkably good at detecting many animals' emotional states just from hearing their calls.
I Hear You
The idea that all animals transmit emotional information in their calls goes all the way back to Darwin. In "The Descent Of Man," he mused that all air-breathing vertebrates can make noise, and when fear or agitation made their muscles contract, those noises most likely changed. If those noises proved useful — say, a loud cry helped the herd escape danger — then the noisy animals would have survived to pass those noises on to their offspring, where it would have been refined and amplified over the following generations.
A research team led by Dr. Piera Filippi from the Max Planck Institute for Psycholinguistics took that one step further: if emotional sounds are a product of evolution, then species that share a common ancestor should share fundamental qualities of those sounds. And if that's the case, one species should be able to tell the emotional state of another species from its call.
Talk With The Animals
For their study, which was published in July 2017 in Proceedings of the Royal Society B, 75 people who spoke either English, German, or Mandarin natively listened to audio recordings of nine different species. Those species ran the gamut of air-breathing vertebrates: mammals including the giant panda, the African elephant, the barbary macaque, and the domestic pig; amphibians including the hourglass tree frog; reptiles including the American alligator; and birds (yes, still technically reptiles) including the black-capped chickadee and the common raven. Oh, and one more mammal: other humans. Each recording depicted either a "high" or "low arousal" state — that is, agitated or relaxed, which they based on knowledge of what the animal was doing during the recording. Give them a listen in the playlist below:
Across the board, people were able to correctly identify whether the animal's call was high or low arousal. Even the volunteers' least accurate responses — the macaque came in at just 60 percent accuracy — were still higher than expected by chance. Three-quarters of the animals got 85 percent accuracy or higher.
This was only nine different species (eight, if you don't count humans) but the researchers think that these results probably extend to all air-breathing vertebrates. The fact that these results were the same regardless of the language the volunteers spoke suggests that this ability is rooted deep in our biology. And why wouldn't it be? We don't just benefit from the alarm calls of our own kind. It benefits your survival to know whether that alligator is feeling threatened, or if a flock of birds was frightened by a predator that could eat you. Yet again, science shows that we have more in common with the natural world than we realize.