Animal communication can look very different, including flashing lights, chirping sounds, body movements, and songs. But beneath that diversity, scientists are beginning to discover surprising patterns.
A new study suggests that many animal species, from insects to mammals, may “talk” at roughly the same rhythm, about two beats per second. And that shared tempo may not be a coincidence, but a reflection of how our brains are wired to process the world.
Many animals, same rhythm
Researchers have found that many communication signals across species fall within fairly narrow ranges. Over and over again, the animal seemed to emit a rhythmic signal at about 2 hertz, or about 2 pulses per second.
The pattern appeared in an amazing variety of creatures. It was not limited to one branch of the animal kingdom or one type of signal.
“There appears to be a large number of organisms that signal and communicate within a relatively narrow range of tempos,” said study co-author Guy Amichai, a researcher at Northwestern University.
“They all seem to be stuck at about 2 hertz, maybe 3 hertz. In principle, they could communicate at other rhythms as well. Physically, there’s nothing to prevent them from communicating at, say, 10 hertz, but in practice they can’t.”
Researchers suggest that a tempo of about 2 hertz is easier for the brain to process because it resonates with many species, including humans, fireflies, sea lions, and frogs.
Looks like the camera caught it
The idea began on a field trip to Thailand, where Amichai and colleagues were collecting footage of fireflies flashing en masse in the countryside. After observing them for a long time, he noticed something strange.
The flashing fireflies seemed to overlap with the chirping of crickets nearby. For a moment, it seemed as if two very different species were somehow keeping time with each other.
“At one point, I thought the flashing fireflies and the chirping of nearby crickets were synchronized,” Amichai said.
When the researchers examined the recordings more closely, they discovered that the insects were not actually synchronized. Although they were emitting signals independently, they both emitted signals at a very similar pace, about 2 to 3 pulses per second.
Rhythms throughout the animal kingdom
This coincidence prompted researchers to look more broadly. They looked at previously published research covering different types of animal communication.
Their research included the lights of fireflies, the chirps of crickets, the calls of frogs, courtship expressions of birds, light and sound pulses of fish, and both vocal and physical signals of mammals. The animals varied widely in size, environment, and communication style.
Still, many of them repeated signals in the range of about 0.5 to 4 hertz. Whether the message was sound, light, or movement, the basic tempo was the same.
This was particularly interesting because it seemed that the limitations didn’t just come from the body. Some animals can clearly signal faster when needed.
“When you try to catch fireflies, they panic and blink much faster,” Amichai says.
“Biomechanically, they can send signals faster, so we wondered if there might be a deeper reason why a completely different system sends signals at this tempo and not others.”
sweet spot of the brain
Possible answers came into focus when the researchers met theoretical physicist Vijay Balasubramanian of the University of Pennsylvania at a conference in conjunction with the National Institute for Theoretical Mathematics. Balasubramanian pointed out that individual neurons operate on similar time scales.
Neurons need time to gather information and reset before firing again. Therefore, simple neural circuits may be particularly responsive to signals that arrive every few hundred milliseconds.
To explore this idea, the researchers built computer models of basic neural circuits. They then tested how those circuits responded to signals delivered at different tempos.
The model had the strongest response in the same range seen in the animal data, around 2 hertz. This supports the idea that communication may have evolved to match the rhythms that the brain can process most efficiently.
“There’s some subtlety here; getting the ‘carrier’ signal in the right tempo range is likely the key to communicating effectively,” said study co-author Daniel Abrams, professor of engineering science and applied mathematics at Northwestern University.
“While the tempo itself may not convey any information, it simply acts as a baseline to grab attention, and the actual content is sent over it so that the notes follow the beat of the song.”
echoes of human life
Researchers also think this pattern may help explain familiar rhythms in human behavior. The researchers noted that popular music is often close to 120 beats per minute, which is the same as 2 hertz.
“The rhythm is perfect for our bodies, our limbs,” Amichai said. “We walk at about 2 hertz, so it’s easy to dance to 2 hertz music.”
“Of course, with more experimental music, the beats can be significantly different. But if you turn on the radio and hear Taylor Swift, it’s often 2 hertz.”
This discovery does not prove that all these rhythms come from exactly the same source. But this raises the possibility that animals, including humans, share common timing preferences that are rooted in the way their nervous systems work.
Amichai now hopes other scientists will experiment directly with more species to investigate how their brains respond to different communication tempos. It could indicate whether this rhythm is indeed a widespread feature of animal nervous systems.
“It’s tempting to think there’s a deeper connection here; perhaps we all share the same wavelength. But we’re still investigating what this means,” he concluded.
The study is published in the journal PLOS Biology.
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