Humans Still Understand Chimpanzee and Bonobo Gestures

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Definition

Great Apes

The first apes evolved about 25 million years ago and were a very diverse group by 20 million years ago. Within the last 10 million years, many ape species became extinct as the earth's climate cooled and dried, and their forested environments changed to woodland and grassland. There are now only about 20 living species of apes, and they are divided into two major groups. These are the:

• Lesser Apes, containing the gibbons
• Great Apes, containing the orangutans, gorillas, chimpanzees, and humans

The Hominidae, whose members are known as the great apes or hominids, are a taxonomic family of primates that includes eight extant species in four genera: Pongo (the Bornean, Sumatran, and Tapanuli orangutan); Gorilla (the eastern and western gorilla); Pan (the chimpanzee and the bonobo); and Homo, of which only modern humans (Homo sapiens) remain. The 8 Great Apes Are:

• Bonobo (also known as pygmy chimpanzee), Pan paniscus
• Bornean orangutan, Pongo pygmaeus
• Chimpanzee, Pan troglodytes
• Eastern gorilla (includes two subspecies: mountain gorilla and Grauer's/eastern lowland gorilla), Gorilla beringei
• Human, Homo sapiens. Humans are primates and are classified along with all other apes in a primate sub-group known as the hominoids (Superfamily Hominoidea).
• Sumatran orangutan, Pongo abelii
• Tapanuli orangutan, Pongo tapanuliensis
• Western gorilla, Gorilla gorilla

Main Digest

Towards a Great Ape Dictionary: Inexperienced Humans Understand Common Nonhuman Ape Gestures - PLoS Biology.

Humans retain an understanding of gestures made by other great apes, even though we no longer use them ourselves, according to a study by Kirsty E. Graham and Catherine Hobaiter at the University of St Andrews, Scotland, publishing January 24th in the open access journal PLOS Biology.

The discovery of gestures used by great apes provided the first evidence of intentional communication outside human language, and over 80 such signals have now been identified.

Many of these gestures are shared across non-human apes, including distantly related apes such as chimpanzees and orangutans. However, despite humans being more closely related to chimpanzees and bonobos, these ape gestures are no longer thought to be present in human communication.

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Researchers tested people's understanding of the ten most common gestures used by chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) using an online game.

Over 5,500 participants were asked to view 20 short videos of ape gestures and select the meaning of the gesture from four possible answers. They found that participants performed significantly better than expected by chance, correctly interpreting the meaning of chimpanzee and bonobo gestures over 50% of the time.

Providing participants with contextual information about what the apes in the video were doing only marginally increased their success rate in interpreting the meaning of the gesture.

Video playback experiments have traditionally been used to test language comprehension in non-human primates, but this study reversed the paradigm to assess humans' abilities to understand the gestures of their closest living relatives for the first time.

The results suggest that although we no longer use these gestures, we may have retained an understanding of this ancestral communication system. The authors say that it remains unclear whether our ability to understand specific great ape gestures is inherited or whether humans and other great apes share an ability to interpret meaningful signals because of their general intelligence, physical resemblance, and similar social goals.

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Graham adds:

"All great apes use gestures, but humans are so gestural - using gestures while we speak and sign, learning new gestures, pantomiming, etc. - that it's really hard to pick out shared great ape gestures just by observing people. By showing participants videos of common great ape gestures instead, we found that people can understand these gestures, suggesting that they may form part of an evolutionarily ancient, shared gesture vocabulary across all great ape species, including us."

Attribution/Source(s):

This peer reviewed article relating to our Deaf Communication section was selected for publishing by the editors of Disabled World due to its likely interest to our disability community readers. Though the content may have been edited for style, clarity, or length, the article "Humans Still Understand Chimpanzee and Bonobo Gestures" was originally written by PLOS, and published by Disabled-World.com on 2023/01/24 (Updated: 2023/01/25). Should you require further information or clarification, PLOS can be contacted at plos.org. Disabled World makes no warranties or representations in connection therewith.

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