Can toddlers and apes teach us lessons about how language evolved? Study finds striking similarities in their communication

The way toddlers and apes communicate is 'strikingly similar' - and much more alike than initially believed.

This is the conclusion of UCLA researchers who, for the first time, have compared the development of gestures in bonobos, chimpanzees and humans.

Their findings provide new evidence that the origins of language can be found in gestures.

The UCLA psychologists analysed a year's worth of video footage of a chimpanzee, a bonobo and a young girl. Gestures made by all three species included reaching, pointing with fingers or the head, and raising the arms to ask to be picked up

The UCLA psychologists analysed a year’s worth of video footage of a chimpanzee, a bonobo and a young girl.

Gestures made by all three species included reaching, pointing with fingers or the head, and raising the arms to ask to be picked up.

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During initial communication development, gestures were dominant in all three species.

After some time, all three species increased their symbol production - words for the child and shapes for the apes.

TESTING FOR A COMMON LANGUAGE

The apes included in the study were named Panpanzee, a female chimpanzee, and Panbanisha, a female bonobo.

They were raised together at the Language Research Center in Atlanta, which is co-directed by Sue Savage-Rumbaugh, a co-author of the study. 

There, the apes learned to communicate with caregivers using gestures, vocalizations and visual symbols called lexigrams.

‘Lexigrams were learned, as human language is, during meaningful social interactions, not from behavioural training,’ said the study's lead author, Kristen Gillespie-Lynch.

The human girl grew up in her parents' home, along with her older brother. Where the apes' symbols were visual, the girl's symbols took the form of spoken words.

Video analysis for her began at 11 months of age and continued until she was 18 months old; video analysis for the two apes began at 12 months of age and continued until they were 26 months old.

During initial communication development, gestures were dominant in all three species. After some time, all three species increased their symbol production- words for the child and shapes for the apes

‘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, a professor of psychology at UCLA.

In 1872, Charles Darwin claimed that the same facial expressions and basic gestures occur in human populations worldwide, implying that these traits are innate.

The study takes Darwin's conclusion a step further by improving understanding on the co-evolution of gestures and speech.

‘This finding suggests that the ability to combine gesture and vocalisation may have been important for the evolution of language,’ Greenfield said.

The study was published in the open-access journal Frontiers in Psychology.

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The researchers concluded that humans inherited a language of gestures and a latent capacity for learning symbolic language from the last ancestor shared with chimpanzee and bonobo relatives - an ancestor they believe lived around six million years ago.

The evolution of human language built on capacities that were already present in the common ancestor of the three species, the psychologists report.

In 1872, Charles Darwin claimed that the same facial expressions and basic gestures occur in human populations worldwide, implying that these traits are innate. The study takes Darwin's conclusion a step further by improving understanding on the co-evolution of gestures and speech

The researchers concluded that humans inherited a language of gestures and a latent capacity for learning symbolic language from the last ancestor shared with chimpanzee and bonobo relatives - an ancestor that lived around six million years ago