Gestures Across Species: How do Apes and Humans Compare?
“The similarity in the form and function of the gestures in a human infant, a baby chimpanzee and a baby bonobo was remarkable,“ said Patricia Greenfield, UCLA Professor and co- author of the study.
The study marks the first time data of this kind has been used to compare gesture development across species.
The two female apes used in the study were raised together in Atlanta at the Language Research Center. The apes were taught to communicate with lexigrams, which are made up primarily of gestures, sounds and symbols. The human infant was raised at home with her family.
For the study, the human infant was filmed in her home from age 11 months to 18 months old. The apes were filmed from 11 months to 26 months old. The overall findings of the study support the “gestures first” theory.
In the first half of the study all three species communicated dominantly with gestures. In the second half all three began to use more symbols. The child used more words while the apes used more lexigrams.
“Gesture appeared to help all three species develop symbolic skills when they were raised in environments rich in language and communication,“ said Kristen Gillespie-Lynch , who conducted the research while she was a grad student at UCLA.
The gestures made by both the child and the apes incorporated; pointing with their fingers, reaching, and raising their arms when they wished to be picked up. The researchers noted how amazing it was that all three species were “predominately communicative”. Communicative meaning that there was eye contact present while both the human and apes were using gestures, along with some sort of vocalization or expectation of a response from their conversation partner.
Gestures are one of the first steps in human language evolution however the researchers also found that the move from gestures to language is accompanied by the “co-evolution of gestural and vocal communication.” Evidence of this was seen in the study when the child often added vocalizations to her gestures while the apes did not.
“This finding suggests that the ability to combine gesture and vocalization may have been important for the evolution of language,“ Greenfield said
The researchers concluded that the evolution of human language is built on a language of gestures and symbols from our common ancestor shared with the chimpanzee and bonobo.
While there are distinct differences in the way humans and apes ultimately communicate, this study shows that there are also many similarities in how we learn to interact and communicate with the world around us.
For more information on apes and emotion be sure to check out Chimps Make Emotional Choices Too! and check out the entire article at ScienceDaily or read the abstract in Frontiers journal in Psychology.