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Humans and animals like the same sounds, new research reveals, proving Charles Darwin correct.
The findings show that people showed preferences for calls that other species find the most attractive.
Scientists say the study proves Victorian naturalist Darwin was right when he noted that animals seem to have a “taste for the beautiful” that sometimes parallels our own leanings.
Brightly colored butterfly wings, the sweet aromas of flowers, and the melodies of songbirds all evolved as signals that help animals breed.
But the new study shows people also find the same signals pleasing to our senses.
Experts from the Smithsonian Tropical Research Institute (STRI) in Panama collaborated with researchers in the United States, Canada, and New Zealand to show that humans and animals express the same subjective preferences for one type of signal – particular animal mating calls.
Across the range and complexity of the animal sounds found in nature, humans and other species also showed “overlapping preferences” for certain qualities of an animal’s call.
The findings, published in the journal Science, indicate that preferences for some animal sounds are more universal than previously known.
In the early 1980s, late STRI staff scientist Dr. Stanley Rand and STRI research associate Dr. Michael Ryan showed for the first time that in the tropical rainforests of Central America, a female túngara frog’s preference for a mate depends on the complexity of the male’s call.
In the new study, Dr. Ryan, now also a Professor at the University of Texas at Austin, and his colleagues wanted to know whether human preferences for certain animal calls, including those from male túngara frogs, correlate with the preferences of female animals.
Study lead author Dr. Logan James, a STRI research associate, said: “After witnessing those female preferences Stan and Mike discovered when I got to measure them myself, I became fascinated with the question of where these preferences come from.
“Plus, since that team released their initial findings, we’ve found that other animals, including eavesdroppers such as blood-sucking flies and frog-eating bats, also prefer complex calls.
“This got us wondering how common acoustic preferences may be.”
The team tested humans’ preferences for different animal sounds using an online computer game.
More than 4,000 human participants from around the world were presented with pairs of animal sounds from 16 different species across the animal kingdom.
They were asked to express their preference for one or the other.
The animal sounds were all recorded in previous research studies, and within each pair, the animal from which the sounds came is known to display a preference for one of the two.
The research team then tested whether humans showed a preference for the same sounds the animals preferred.
Study senior author Professor Samuel Mehr, of Yale University in the US, said: “In gamified citizen science, people volunteer for experiments simply because they’re fun and interesting.
“The method is perfect for answering questions from evolutionary biology, where we aim to study phenomena across many species as opposed to just a few.
“Our game enabled us to test lots of humans’ preferences for lots of different sounds.”
The researchers found “broad overlap” between human and animal sound preferences.
The team discovered that the stronger an animal’s preference for a particular sound, the more likely it was that a human would select that sound as their favorite.
And the human participants were quicker to select the more attractive sound.
Agreement between animals and humans was strongest for lower-frequency sounds and those with acoustic adornments, such as “trills,” “clicks,” and “chucks.”
Dr. Ryan added, “Darwin noted that animals seem to have a ‘taste for the beautiful’ that sometimes parallels our own preferences.
“We show that Darwin’s observation seems to be true in a general sense, probably due to the many sensory system properties we share with other animals.”
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