Honest signals indicate body size

The chest of a male gorilla is beating. Credits: Jordi Galbany / Dian Fossey Gorilla Fund

The heartbeat of a gorilla is one of the most iconic sounds in the animal kingdom. However, until recently, it was unclear what information the gorillas were communicating when they made these impressive exhibits. A team of international researchers has shown that the beating of the chest is a reliable indication of the size of the beating person’s body. Body size shows the competitiveness of gorillas. Therefore, this information can be important for rival males and females in influencing spouse choice.

Gorilla usually stand on two legs and tap their chest quickly and continuously with their cup-shaped hands. The heartbeat is a unique sound because it is not a vocalization like a frog’s bark, but a form of gesture communication that can be heard and seen. The sound of the drums emitted can be heard from a distance of more than 1 km. The presumed function of a gorilla’s chest beating is to attract women and intimidate rival men.

Researchers record heartbeats and use a technique called photogrammetry to non-invasively size the body size of an adult male wild mountain gorilla monitored by the Dian Fossey Gorilla Fund in Volcanoes National Park, Rwanda. I measured it. They found that large men beat their chests at lower peak frequencies than smaller men. In other words, the beating of the chest conveyed information about the size of the beating person’s body.

“The heartbeat of a gorilla is one of the iconic sounds of the animal kingdom, so it’s great to be able to show that body size is encoded on these magnificent displays,” he said. Edward Wright, the first author of this study, said. Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Body size is an important attribute for many animals as it often reflects their fighting ability and competitiveness. Previous studies by this team have shown that larger males are more socially dominant and more successful in reproduction than smaller males.

Gorilla does not bluff when hitting the chest: honest signals indicate body size

Silverback’s chest beats during the interaction between the groups. Credit: Dian Fossey Gorilla Fund

“Because the duration of the heartbeat is relatively short, you need to be in the right place and at the right time to get the recording, and you need to be away from these big powerful animals, this study It was difficult to do, “says the collaborator. Research assistant of author Eric Ndayishimiye and Dian Fossey Gorilla Fund.

Rival men may pay attention to the body size information sent by the heartbeat of the chest. This allows you to assess the competitiveness of the heartbeater and helps you decide whether to start, escalate, or retreat in an aggressive contest. Women, on the other hand, may use this information to select potential spouses.

Gorilla does not bluff when hitting the chest: honest signals indicate body size

The heartbeat of the silver back chest. Credit: Dian Fossey Gorilla Fund

Interestingly, researchers also found that there was a great deal of variability among men in both the number of beats contained in the beat and the duration of the beat. “This suggests that the heartbeat may have individual characteristics, but further research is needed to test this,” says Wright.

The study is published in the study published in Science report..

Social status, not size, determines the breeding success of female mountain gorillas

For more information:
Chest beating as an honest signal of body size of a male mountain gorilla (Gorilla beringei beringei) Science report, DOI: 10.1038 / s41598-021-86261-8

Provided by Max Planck Society

Quote: Gorilla does not bluff when hitting the chest: Honest signal obtained from on April 8, 2021 Shows the size of the body (April 8, 2021) .html

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Honest signals indicate body size

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