Africa: Wild Chimpanzees Beat the Bush Telegraph Using Tree-Root Rhythms

Chimpanzees don’t just drum on tree roots for fun — they do it in rhythm, and they may be using it to send messages through the forest.

That’s what a team of scientists found after analysing more than 370 recordings from 11 chimpanzee communities in six groups across Africa.

Their findings, published this month in Current Biology, show that chimpanzees are capable of creating rhythmic sequences – something long thought to be mostly human.

By hitting tree roots, the chimps produce low-frequency sounds that can travel more than a kilometre. This could allow them to stay in touch across large distances, even when they’re out of sight.

Choosing the right tree

Chimpanzees aren’t just drumming at random. They make careful choices about where and how they drum.

“They select specific trees and even specific root thickness and height, because the thinnest and widest roots allow them to communicate over longer distances,” said lead author of the studt Vesta Eleuteri, a doctoral student at the University of Vienna.

The pattern of the sound is important too.

“The fact there is a sequence means it’s not just a tree falling. It helps others understand that it’s a chimpanzee hitting,” Eleuteri added.

To test whether the drumming was truly rhythmic, the scientists used methods normally used for studying music in humans.

“We used mathematical and statistical tools to measure patterns in human music and in other species,” explained co-author Andrea Ravignani, a cognitive neuroscientist at Roma Sapienza University.

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Styles across regions

The chimpanzees showed different drumming patterns depending on where they lived.

In West Africa, they tend to drum at regular intervals. In East Africa, they more often switch between short and long beats.

“This could be due to social factors,” said Eleuteri. “Chimpanzees in West Africa are more peaceful and often stay together, while chimpanzees in East Africa are more frequently apart and more aggressive toward other groups.

“So the alternation of short and long rhythms might be a way to say different things and to mark out individuals more clearly.”

Even though the chimps drum in rhythm, the scientists were careful not to suggest they are making music in the same way humans do.

“It’s tempting to draw a link between human music and what we see in chimpanzees,” said Ravignani.

While there are five or six traits that define musical rhythm across almost all cultures – including the ability to create non-random sequences of sound through percussion – he stressed that chimps aren’t simply copying human music.

“Each species has its own sound production system, so it would be wrong to say that chimpanzees share the rhythm of human music,” Ravignani said.

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Unlocking evolution

The discovery is still a major step in understanding our evolutionary past.

“We see that one of our two closest relatives has this core ability to produce non-random percussive sequences,” Ravignani said.

“This is a very big step forward because previous studies looked for other rhythmic building blocks in chimpanzees. And they were not successful. So finding one this time might also tell us more about the story of human evolution, about our shared history with chimpanzees,” he added.

The study supports the idea that some parts of musical behaviour existed before humans and chimpanzees split from a common ancestor about 6 million years ago.

The researchers now want to understand how chimpanzees actually produce these rhythms – whether they use hands, feet or both, and how different parts of the body affect the sound.

There were noticeable differences between sub-species, but not much variation between groups within the same sub-species. That raises another question: could chimpanzees have “rhythmic cultures”?

The team plans to collect more recordings to find out.