Say it with your chest! Male gorillas slap their chests to show females how big and terrifying they are – with larger monkeys producing lower frequency sounds heard a mile away, study reveals
- Researchers studied video and audio recordings of silverbacks in Rwanda
- Larger mountain male gorillas found make a deeper sound than smaller animals
- The patting of each gorilla on the chest is considered unique and acts as an audio signature to help others identify them in dense forest
Silverback gorillas stand up and slap their chests as a form of communication, a study finds.
Analysis of wild male mountain gorillas in Rwanda reveals that a male’s drum sound indicates their size and identity.
German researchers found that larger gorillas make a deeper sound when they hit their chest than their smaller peers, and each individual’s thumping pattern is unique.
It is thought that when silverbacks hit their muscular torso, they transmit their dominance and size to rival men, while at the same time trying to impress women who may be potential partners.
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German researchers found that larger gorillas make a deeper sound than their smaller peers and each individual’s thumping pattern is unique
The researchers studied video taken by the Dian Fossey Gorilla Fund of 25 men living in Volcanoes National Park, Rwanda, and calculated their body size by measuring the distance between their shoulder blades.
The number of beats and stroke frequency were recorded for each gorilla, as well as the animal’s stature and age.
Six men were also audio recorded, recording a total of 36 chest strokes, as well as the duration of the strokes, the number of hits, and the frequency of the sound produced.
The audio recordings showed a correlation between the gorilla’s frequency and body size – larger males made a deeper sound.
“ The gorilla’s breast stroke is one of those iconic sounds from the animal kingdom, so it’s great that we’ve been able to show that body size is encoded in these spectacular displays, ” said Edward Wright, lead author of the Max Planck Institute study. for Evolutionary Anthropology in Leipzig.
Gorilla chest strokes are not vocalizations but are considered a form of gesture communication that can be seen as well as heard.
The drumming sound of a solid silverback hitting his chest with its fists can be heard more than a mile away.
The photo shows four still images of a male silverback gorilla in Rwanda hitting his chest. It is thought that when silverbacks strike their muscular torso, they transmit their dominance and size to rival men, while at the same time trying to impress women.
Known as GSH, this silverback strikes its chest during a group interaction in Volcanoes National Park
The researchers believe the lower frequency sounds are made by larger animals because they have larger air sacs around their larynx that amplify the sound.
Variations in the duration and number of heartbeats were also seen in the visual recordings, but these are not related to body size, the researchers say.
Instead, the team believes that the variations in the number of beats, beat frequency, and total duration allow individual gorillas to be identified and act as an audio signature.
This would help gorillas identify each other in the dense forests they live in, researchers speculate.
Mr. Wright said, “This indicates the possibility that heartbeats have individual signatures, but further research is needed to test this.”
The researchers believe that hitting the chest can also help assess rivals’ fighting ability.
They said female gorillas are likely to use the information to find potential mates.
The findings are published in the journal Scientific reports
Mountain gorillas limit the number of their strong social ties
Gorillas living in small social groups have more high-quality relationships than those in oversized packs.
The smaller number of individuals is believed to allow them to spend more time together and develop stronger bonds.
However, in much larger groups, it can be mentally exhausting trying to maintain good relationships with many other individuals.
As a result, gorillas in large groups have only a few very strong relationships and many ‘weak’ bonds.
Scientists have identified up to seven types of primate relationships – ranging from close maternal-offspring ties to ‘weak’ associations
Usually mountain gorillas live in groups of between 12 and 20, and the study found that this size is ideal and produces the richest range of relationships.
In smaller or larger groups – sometimes as many as 65 gorillas – this diversity decreases.