Chimps alarm their friends when poisonous snakes are nearby

The findings showcase how complex systems of communication can evolve without language.
By Brooks Hays  |  Nov. 15, 2017 at 4:32 PM
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Nov. 15 (UPI) -- New research shows chimpanzees alert their friends and relatives to the presence of poisonous snakes.

The findings, published Wednesday in the journal Science Advances, suggest chimps are capable of a more advanced combination of communication and cooperation than previously thought.

"There seems to be more going on in chimpanzee communication -- and possibly in other animal communication, especially the vocalization part -- than has been assumed possible before," Catherine Crockford, a researcher at the Max Planck Institute for Evolutionary Anthropology in Germany, told The Verge.

To test how chimps keep their peers apprised of serpentine dangers, scientists make snake decoys out of chicken wire and plaster. They were designed to mimic gaboon and rhinoceros vipers, both deadly species found in the forests of Uganda.

Researchers placed the fake snakes along jungle paths frequented by local chimps and set up video cameras to record their reactions. As revealed by the video footage, roughly a third of the passing chimps stopped and vocalized an alarm. After issuing their warning, the chimps glared at the location of the snake, rotating his or her vision between the point of danger and the other chimps.

In a followup experiment, scientists played one of two recorded calls prior to a chimp passing the fake snake. One recording featured the call vocalized by chimps at rest, while the second recording featured an alarm vocalization.

When chimps heard the alarm call prior to spotting the snake, they were less likely to issue an alarm themselves. And if they did, it was issued with less intensity. When chimps heard a resting call before seeing the viper decoys, they issued a greater number of alarm calls and emphasized them with body language.

Researchers also found the chimpanzees gave more impassioned warnings to friends and relatives than other local chimps.

According to Crockford, the findings can help scientists better understand how complex systems of communication can evolve without language. The research can also highlight the ways social behaviors are motivated by strong relationship bonds.

"I think it helps us learn much more about ourselves, how our brains work" she said.

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