Animals do all sorts of things to attract each other as potential mates. Many birds, for example, produce feathers with elaborate color patterns – from the iridescent plumage of many hummingbirds to the famously brilliant tail of a peacock. Charles Darwin, an early pioneer in the theory of evolution, saw these colors and concluded that they exist because other birds find them attractive.
But this raised a peculiar question: Why did Darwin himself find these colors beautiful too?
Indeed, he noted that some animals have “nearly the same taste for the beautiful as we have,” a simple observation with radical implications. Our sense of beauty might be something we humans share with other animals, rooted in biology.
Over a century after Darwin made his observations, my colleagues and I decided to actually test this idea.
I am an expert in animal communication, with a focus on sound production and perception. I have worked with species such as zebra finches, fringe-lipped bats and túngara frogs. For example, late at night in Panama, I have watched remote video feeds of female túngara frogs as they listened to calls that I played from different speakers. Eventually a female will hop toward one speaker, revealing which of the calls she preferred.
Túngara frog calls are a distinct part of the nocturnal jungle soundscape in Panama.
Kim Hunter
Could it really be possible that this tiny frog and I are attracted to some of the same sounds? What might shared preferences say about what animals and people have in common? We needed data to find out.
A global experiment
To test Darwin’s idea properly, we needed two things: a large collection of animal sounds that had already been tested on animals, and a large number of human listeners willing to give their opinions.
For the sounds, we drew on decades of published research, including some of our own as well as studies from generous colleagues who let us use their recordings. We ended up with 110 pairs of sounds from 16 different species, including frogs, insects, birds and mammals. In each pair, the sounds are used to attract potential mates; scientists had already found which of the two versions that animals tended to prefer.
Human volunteers played a game that asked them which animal sound they preferred.
Logan S. James
For the human listeners, we built a gamified online experiment played by over 4,000 participants from around the world. The task was quite simple: We played each pair of sounds in random order, and then asked which one the human participant liked more.
What we found
The results were striking. Across our dataset, including animals separated from human beings by hundreds of millions of years of evolution, people tended to agree with the animals about which sound was more pleasant.
Amazingly, the stronger the animal’s preference, the more likely humans were to agree. We also found that…
