Chimps Communicate Through Rhythmic Tree Drumming

ChimpanzeeChimpanzees are known for their booming and melodic “pant hoot” vocalizations that echo throughout the rainforest. But few are aware of another equally important and fascinating means of chimpanzee communication—stylistic drumming on buttress roots of trees with their feet. The significance of this drumming has eluded scientists for decades. New research, however, has revealed that these symphonic displays serve not only as a show of physical prowess, but as a tool for long-distance communication.


DRUM SOLOS ACCOMPANY PANT HOOTS
Groundbreaking field research conducted in Uganda by psychologist Katie Slocombe of the University of York in the United Kingdom and published in American Journal of Physical Anthropology suggests that buttress tree drumming contains unique rhythmic patterns to broadcast a chimp’s location to distant troop mates. In fact, drumming sounds can travel through thick jungle for at least a kilometer. Moreover, Slocombe discovered that each chimp displays a distinct drumming style and cadence, with individual differences in the use of doublets, pauses and beats per bout that serve as musical identity to troopmates. When chimps are traveling across vast terrain, Slocombe hypothesized that “drumming patterns may act as individually distinctive long-distance signals that, together with pant hoot vocalizations, function to coordinate the movement and spacing of dispersed individuals within a community.”

 
Additionally, researchers determined that drum frequency is related to age and gender of the chimp. For example, older, more experienced males used tree drumming more than other members, while social rank or the presence of female counterparts was not correlated to drumming frequency. The most significant factor related to drumming, however, was movement. Slocombe and colleagues found that chimps on the move paired hoots with buttress drumming about 75 percent of the time, compared to only 40 percent while resting and 10 percent while eating.

 
ROOTS OF HUMAN MUSIC
Could these acoustic findings provide insight into how rhythm emerged in human lineage? The genetic and evolutionary similarities between humans and chimps are well established, and the earliest humans may have utilized drumming to coordinate movement over long distances, suggests Slocombe. However, Adam Clark Arcadi, an anthropologist at Cornell University, cautions that additional research is still required to clarify the significance of tree drumming amongst chimps and to determine the role of rhythmic drumming in human evolution.

 
VOCABULARY
• Pant hoot
• Beats per bout
• Doublets
• Buttress roots

 
EXTENSION QUESTIONS
• What are pant hoots? What other means do chimps use to communicate?
• What other animals use vocalizations and sounds to communicate?

 

By Julianne Glaser

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