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Bonobos speak like HUMAN BABIES: Apes use high-pitched 'peeps' just like infants learning to talk

Scientists studied sounds made by wild bonobos in the Congo jungle
The apes produced high-pitched 'peeps' in a variety of different situations
These echo the sounds produced by babies before they learn to speak
Biologists say this could shed light on the evolution of speech in humans

Published: 06:28 EST, 4 August 2015 | Updated: 07:34 EST, 4 August 2015

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They are our closest relatives in the animal kingdom, sharing 98 per cent of their DNA with humans, but bonobos may share more with our species than was believed possible – a common 'language'.

Researchers have discovered bonobos living in the wild communicate with each other in much the same way as human infants.

They use high-pitched calls known as peeps, which can be adapted to a range of different situations and to convey emotional states. Scientists say these are similar to the babbles produced by babies.

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Bonobos use high-pitched peeps to communicate with one another in a variety of situations, like feeding as shown above. Scientists believe this is similar to the way human babies use babbled noises, known as protophones, to indicate what they are feeling or what they want before they learn to speak

The findings could provide valuable new insights into how humans developed the ability the use language to communicate in the first place.

The short, high pitched peeps produced by bonobos may be similar to the first attempts by our early ancestors to communicate within their own groups.

HUMANS HAVE PRIMITIVE HANDS

Humans like to think of themselves as the peak of the evolutionary tree, honed by millions of years of evolution that sets us apart from our closest animal cousins.

But new research now suggests one part of our body – our hands – is actually more primitive than those of chimpanzees.

Analysis of the anatomy of the hands of living and extinct apes has revealed that human hands have actually evolved little since we shared a common ancestor with chimpanzees.

Chimps by contrast have developed elongated fingers to help make them better suited to life in the trees.

Human hands have retained their relatively long thumbs in relation to their index fingers, making them much more similar to the appendages of gorillas.

The new findings, however, suggest the proportions of the human hand appears to have been in place long before we separated from chimpanzees and bonobos, from the genus Pan, around five million years ago.

The researchers looked at the acoustic structure of the peeps produced by bonobos living in the jungle of the Congo and found they identical when used in a variety of positive and neutral situations like feeding, travelling, resting and grooming.

It means the great apes are instead interpreting the calls based on the contexts in which they were made, which requires them to make intelligent inferences about the meaning.

This echoes the way human babies produce protophone sounds, such as the babble-like grunts they make before they start using recognisable words. It is thought to be a key step towards learning to speak.

These differ from other common noises like laughter and crying as they are used independently of the emotional state and context.

Dr Zanna Clay, a primatologist and psychologist at the University of Birmingham who led the study, said: 'When I studied the bonobos in their native setting in Congo, I was struck by how frequent their peeps were, and how many different contexts they produce them in.

'It became apparent that because we couldn't always differentiate between peeps, we needed understand the context to get to the root of their communication.

'It appears that the more we look, the more similarity we find between animals and humans.'

Many animals produce calls that are only used in certain contexts.

The researchers found the bonobos used peep sounds in a variety of emotionally neutral or positive situations, such as feeding, travelling, resting and grooming, as shown above. They are thought to infer meaning based on the context the peep call is used in, which requires a high level of intelligence

Bonobos using 'peeps' similar to sounds of human babies

Indeed researchers studying gibbons, for example, have found they produce wide repertoire of noises that are dependent on what they are doing at the time.

The new research, however, which is published in the journal PeerJ, may represent a key 'missing link' in the evolutionary steps from the fixed animal vocalisations used in specific contexts to human language.

It suggests this may have occurred around six or seven million years ago when humans and bonobos are thought to have shared a common ancestor that had split from the other apes.

Bonobos have previously been seen to make tools from branches and rocks much like early human species may have done.

Although they look similar to chimpanzees, they are a separate species and tend to live in far more peaceful societies.

Scientists believe bonobo communication could provide valuable insights into how humans first began to speak as a shared ancestor with bonobos around six million years ago may have moved away from using context fixed animal calls to using these more complex sounds that are interpreted depending on the situation

Babies produce noises known as protophones which they use to express themselves before they have learned to speak. This has been found to be similar to the noises produced by bonobos in the wild

They are among the most vocal of the great apes and have around 15 different call types that are known to be linked to particular emotional states, such as screaming, threat barks, greetings and alarm calls.

However, the peeps they produced appeared to be more flexible and were used in a variety of contexts.

Writing in PeerJ, Dr Clay and her colleagues said: '(In human infants) protophones were most commonly associated with neutral facial expressions compared to cry and laughter, which were tightly linked to negative and positive affect, respectively, further highlighting their greater emotional detachment.

'Interestingly, bonobo peeps are also typically produced with a neutral facial expression, produced while the mouth remains closed without any particular facial expression

'Our data suggest that the capacity for functional flexibility has evolutionary roots that predate the evolution of human speech.'