Whatever the fifth you are, we all have in mind the images of the great King Kong beating his chest with the face of few friends. But do you know exactly what function this movement has in nature? An international research group seems to have come up with an explanation in their article published in the journal Scientific Reports.
According to scientists, punches to the chest would play a fundamental role in the intra and intersex competition of this species. In addition, although it has not yet been proven, it seems that one of the keys that gorillas use to evaluate the competitive ability of their rivals is based on the acoustic signals from the blows that they are given to the chest. This fact is due to the fact that the sound produced by the impacts could reliably indicate the body size of their congeners. Who would mess with someone twice his size?
After examining the relationship between body size (back width), peak rate, and three temporal characteristics of the chest beat: duration, number of beats, and beat rate in wild adult male mountain gorilla sound recordings, the Linear mixed models did not find a consistent relationship between body size and measured temporal characteristics. However, they did find positive correlations between male body size, dominance range, and reproductive success, a fact that led the scientists to conclude that the gorilla’s chest beat is an honest sign of competitive ability.
One of the study authors, Jordi Galbany, said in an interview for 324 that ” the behavior of the blow to the chest is typical of gorillas – especially adult males – it had always been described as a show of force related to the social status and threatening behaviors … This type of behavior is the climax of a whole demonstration: the gorilla begins to make vocalizations similar to short howls, stands up and runs on its legs while striking hard on the chest with the two palms of the hands alternately and produces an impressive sound, like the roll of a kettledrum. […] Male gorillas beat their chest once every twenty hours of observation, but can do it every few minutes when there is an interaction between two groups of gorillas. “
Finally, the scientists discovered that larger males emit more serious blows when hitting the chest, that is, with lower frequencies. Hearing this sound, which could go up to a kilometer away, nearby male gorillas might decide not to approach to avoid conflict, or it could help females to find a possible mate. Ultimately, the results of this study emphasized the potential of non-voice signals to convey important information in mammalian communication.
References:
Duran, X. (2021, April 9). One study deciphers what gorillas say when they hit their chest. CCMA. https://www.ccma.cat/324/un-estudi-desxifra-que-diuen-els-gorilles-quan-es-colpegen-el-pit/noticia/3090114/
Wright, E., Grawunder, S., Ndayishimiye, E., Galbany, J., McFarlin, S. C., Stoinski, T. S., & Robbins, M. M. (2021). Chest beats as an honest signal of body size in male mountain gorillas (Gorilla beringei beringei). Scientific Reports, 11(1). https://doi.org/10.1038/s41598-021-86261-8
