Chimpanzees Use Rhythmic Drumming to Communicate Across Forests
New research by cognitive scientists and evolutionary biologists has found that chimpanzees drum rhythmically, using regular spacing between drum hits. The findings, published in the Cell Press journal Current Biology, reveal that eastern and western chimpanzees—two distinct subspecies—exhibit clearly different drumming rhythms. According to the researchers, this suggests that the foundational elements of human musicality may have originated in a common ancestor shared with chimpanzees.
“Based on our previous work, we expected that western chimpanzees would use more hits and drum more quickly than eastern chimpanzees,” says lead author Vesta Eleuteri of the University of Vienna, Austria. “But we didn’t expect to see such clear differences in rhythm or to find that their drumming rhythms shared such clear similarities with human music.”
Earlier studies showed that chimpanzees produce low-frequency sounds by drumming on buttress roots, which are large, wide roots that rise above the soil. Researchers suggest that chimpanzees use these drumming patterns to communicate information across both short and long distances in the rainforest.
“Our previous study showed that each chimpanzee has their own unique drumming style and that drumming helps to keep others in their group updated about where they are and what they’re doing—a sort of way to check in across the rainforest,” Eleuteri says. “What we didn’t know was whether chimpanzees living in different groups have different drumming styles and whether their drumming is rhythmic, like in human music.”
To find out, Eleuteri and her team, including senior authors Catherine Hobaiter of the University of St. Andrews in the UK and Andrea Ravignani of Sapienza University in Rome, teamed up with other chimpanzee researchers to study 371 drumming bouts in 11 chimpanzee communities, including six populations and two subspecies.
After analyzing the drum patterns, they found that chimpanzees drum with rhythm and that the timing of their hits is non-random and often evenly spaced. Eastern and western subspecies also exhibited different drumming patterns; western chimpanzees used evenly spaced hits while eastern chimpanzees more often alternated between hits at shorter and longer time intervals. They also found that western chimpanzees hit their “drums” more, using a faster tempo, and integrated their drumming earlier in their pant-hoot vocalizations.
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