Animal Communication May Share a 2 Hertz Rhythm

Animal communication takes remarkably varied forms, including light flashes, chirps, physical gestures and songs. Yet scientists are beginning to identify an unexpected regularity beneath this diversity.

New research indicates that a wide range of animals, spanning insects and mammals, may be “speaking” at almost an identical pace: around two beats each second. Rather than being accidental, this common tempo could reflect the way brains are structured to interpret the world.

Many animals share the same rhythm

The scientists discovered that communication signals from numerous species sit within a relatively narrow band. Repeatedly, animals produced rhythmic cues at approximately 2 hertz, equivalent to about 2 pulses per second.

This trend emerged in an unusually broad selection of creatures. It was neither confined to a particular animal group nor restricted to a single signalling method.

“There seems to be an abundance of organisms signaling or communicating at a relatively narrow band of tempos,” said the study’s co-author, Guy Amichay, a research associate from Northwestern University.

“They all seem to stay around 2 or maybe 3 hertz. In principle, they could communicate at other rhythms. Physically, there is nothing preventing them from communicating at, say, 10 hertz, yet they do not.”

The team suggests that a rhythm close to 2 hertz could be simpler for brains to handle, as it appears to resonate among many species, from people and fireflies to sea lions and frogs.

A pattern captured on camera

The observation originated during a research trip to Thailand, where Amichay and his colleagues were filming fireflies flashing in synchrony across the countryside. After observing them for extended periods, he spotted an unusual apparent connection.

The fireflies’ flashes appeared to coincide with the calls of crickets nearby. Briefly, it seemed that two highly different species could be marking time together.

“At some point, I thought that the flashing of the fireflies and the chirping of the nearby crickets were in sync,” Amichay said.

Closer analysis of the footage revealed that the insects were not synchronising after all. They signalled separately, but at a closely matching rate of roughly two to three pulses each second.

A rhythm throughout the animal world

This apparent coincidence led the researchers to investigate the question on a far wider scale. They reviewed earlier published research into numerous forms of animal communication.

Their review encompassed firefly flashes, cricket chirps, frog calls, birds’ mating displays, fish signals involving light and sound, and mammals’ vocal and bodily cues. These species varied enormously in size, habitat and mode of communication.

Nevertheless, many repeated their signals at rates between roughly 0.5 and 4 hertz. The same underlying pace surfaced whether a message was conveyed through movement, sound or light.

The result was particularly notable because the apparent constraint did not seem to be solely physical. Certain animals can plainly communicate at much higher speeds when circumstances demand it.

“If you try to catch a firefly, it panics and flickers much faster,” Amichay said.

“Biomechanically, they are able to signal faster. So, we wondered if there might be a deeper reason why very different systems signal at this tempo and not any other tempo.”

The brain’s ideal tempo

A possible explanation emerged when the researchers encountered University of Pennsylvania theoretical physicist Vijay Balasubramanian at a conference associated with the National Institute for Theory and Mathematics in Biology. Balasubramanian noted that individual neurons function on a comparable timescale.

Neurons require a period to collect information and reset before they can fire once more. As a result, basic neural circuits may react most readily to signals arriving every few hundred milliseconds.

To investigate this possibility, the team created computer simulations of simple neural circuits. They then assessed the circuits’ responses to signals presented at a range of tempos.

The simulations produced their most powerful responses in the same region found in the animal evidence: close to 2 hertz. This lends support to the idea that communication evolved in line with the rhythms brains process most effectively.

“There’s a somewhat subtle point here: we suspect that getting the ‘carrier’ signal in the right tempo range is key to communicating efficiently,” said study co-author Daniel Abrams, a professor of Engineering Sciences and Applied Mathematics at Northwestern University.

“It might not be that the tempo itself conveys any information, but it just serves as a baseline for getting attention, with actual content sent on top of it like musical notes following along with the beat in a song.”

Echoes in human life

The researchers believe the pattern could also account for well-known rhythms in human behaviour. They noted that mainstream music commonly falls near 120 beats per minute, the equivalent of 2 hertz.

“That rhythm fits our body; it fits our limbs,” Amichay said. “We walk roughly at 2 hertz, so it’s easy for us to dance to music that’s 2 hertz.”

“Of course, more experimental music can have drastically different beats. But if you turn on the radio and hear Taylor Swift – that’s often 2 hertz.”

The result does not establish that every one of these rhythms has precisely the same origin. It does, however, suggest that animals and humans may share a timing preference arising from how nervous systems operate.

Amichay hopes researchers will now directly study additional species and explore how brains react to communication at varying tempos. Such work may determine whether this rhythm is genuinely a common property of animal neural systems.

“It’s tempting to think there’s a deeper connection here – that maybe we’re all on the same shared wavelength. But we’re still exploring what this might mean,” he concluded.

The study was published in the journal PLOS Biology.