Why gorillas beat their chest

They say the audio frequencies of the chest beats made by larger males are significantly lower than those made by smaller males, therefore giving clues about body size.

Author Edward Wright and his team recorded 25 wild adult male silverback gorillas at Volcanoes National Park in Rwanda. Larger males may have bigger air sacs near their voice box, it is believed, which could be lowering the frequencies of sounds they produce while beating their chests.

Stephen Port: Police officer investigating serial killer's final victim was not told others had died in similar circumstances, inquest told. The experts also observed variations in the duration and number of chest beats made by different gorillas regardless of body size.

Mr Wright, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, said: "The gorilla chest beat is one of those iconic sounds from the animal kingdom, so it is great that we have been able to show that body size is encoded in these spectacular displays.

There is no point in me fighting you because I am likely to lose. I am likely to get injured. But quite why larger animals have lower frequency sounds when pummelling their chest remains something of a mystery. Prof Anna Nekaris, an expert in primates from Oxford Brookes University, who was not involved in the work, said the study highlighted that it was not just humans who make use of body language. This article is more than 7 months old.

Dense vegetation of their natural habitat means male gorillas may not be able to weigh up a rival by sight alone. They, however, emphasized that the duration and number of chest beats were not related to the size of the gorillas. Instead, the team believes the variations in the number of beats, beat rate and total duration may allow individual gorillas to be identified, acting as an audio signature. This would help gorillas identify one another across the dense forests in which they live, researchers speculate.

The research findings will be published in journal, Science Report. Read all the Latest News and Breaking News here. Tags animal Gorilla research.