Wednesday 1 June 2022

Common Ancestor News - Like Humans, Chimpanzees Have Complex Language

Chimpanzees Asanti and Akuna vocalising.

© Liran Samuni, Taï Chimpanzee Project
Chimpanzees combine calls to form numerous vocal sequences | Max-Planck-Gesellschaft

How human languages evolved is something of a mystery. I'm not talking about the neurological and anatomical development that made us able to vocalise and comprehend spoken communications because this is an obvious case of gene-meme co-evolution. What I'm talking about is the evolution of the various sounds into words and so into coded information that conveys a meaning.

This is an even bigger problem for creationists because, apart from the childishly implausible and contradictory accounts in their favourite textbook, the Bible, it offers nothing by way of a rational explanation. Firstly there is the tale that all the descendants of Noah spoke different languages, to account for the handful of Middle Eastern languages the authors were aware of (Genesis 10:1-5). Then we have the contradictory claim that the whole world spoke one language (Genesis 11:1) but God confounded their tongues so they all spoke languages incomprehensible to one another [sic] because he was afraid they would work together to build a tower up to Heaven - which in those days was just above the sky over the Middle East and accessible via a tall enough tower.

But nowhere does the Bible say anything about how we learned to combine different phonics into words. The assumption of the Bible's authors was that, right from start, language was fully formed as some sort of universal given. Even the talking animals (Genesis 3:1-5, Numbers 22:28-30) and plants (Judges 9:13) spoke with human language, using the recombination of human phonics to make the words they spoke, like humans do, even though they lack the neurological and physical means of doing so. Even when God spoke his first words (Genesis 1:3) he used a human combination of human phonics to make meaningful (to humans) words and sentences - in that case, in a language then spoken by no-one else, since there was no-one else to speak it - Ancient Hebrew.

It is of course, nonsensical. Our ability to cooperate in social groups and develop cultures in which agreed combinations of phonetics has agreed meanings, so we can construct new information by an agreed set of rules, is an evolved ability and one which we probably inherited from an ancestor we have in common with chimpanzees, as the work of scientists from the Institut des Sciences Cognitives Marc Jeannerod, Lyon, France, the Department of Neuropsychology, Max Planck Institute for Human Cognitive Sciences, Leipzig, Germany and the Taï Chimpanzee Project, Centre Suisse de Recherche Scientifique, Abidjan, Ivory Coast, shows.

They have discovered that chimpanzees :

… produce hundreds of different vocal sequences containing up to ten different call types. The order of calls in these sequences followed some rules, and calls were associated with each other in a structured manner.

According to the Max Planck Institute’s press release:
Humans are the only species on earth known to use language. We do this by combining sounds to form words and words to form hierarchically structured sentences. The question, where this extraordinary capacity originates from, still remains to be answered. In order to retrace the evolutionary origins of human language, researchers often use a comparative approach – they compare the vocal production of other animals, in particular of primates, to those of humans. In contrast to humans, non-human primates often use single calls –referred to as call types – and rarely combine them with each other to form vocal sequences.

Our findings highlight a vocal communication system in chimpanzees that is much more complex and structured than previously thought.

Tatiana Bortolato, co-author Institut des Sciences Cognitives Marc Jeannerod,
Lyon, France
Consequently, vocal communication in non-human primates seems much less complex than human communication. However, human language complexity does not arise from the number of sounds we use when we speak, which is typically bellow 50 different sounds in most languages, but from the way we combine sounds in a structured manner to form words and hierarchically combine these words to form sentences to express an infinite number of meanings. In fact, non-human primates also use up to 38 different calls to communicate, but they rarely combine them with each other. However, since they have so far not been analysed in great detail, we may not have a full picture of the structure and diversity of vocal sequences produced by non-human primates.

Observing animals in their natural social and ecological environment reveals a previously undiscovered complexity in the ways they communicate

Cédric Girard-Buttoz, first author. Institut des Sciences Cognitives Marc Jeannerod,
Lyon, France
Researchers recorded thousands of vocalisations
Researchers at the Max Planck Institutes for Evolutionary Anthropology and for Cognitive and Brain Sciences in Leipzig and from the Institute of Cognitive Sciences at the CNRS in Bron, Lyon, France, recorded thousands of vocalisations produced by the members of three groups of wild chimpanzees in the Taï National Park in Ivory Coast. They identified 12 different call types and assessed how chimpanzees combine them to form vocal sequences.

Syntax is a hallmark of human language and in order to elucidate the origin of this human ability it is crucial to understand how non-human primate vocalisations are structured.

Emiliano Zaccarella, co-lead author
Department of Neuropsychology
Max Planck Institute for Human Cognitive Sciences
Leipzig, Germany

This is the first study in a larger project. By studying the rich complexity of the vocal sequences of wild chimpanzees, a socially complex species like humans, we expect to bring fresh insight into understanding where we come from and how our unique language evolved.

Catherine Crockford, senior author
Institut des Sciences Cognitives Marc Jeannerod,
Lyon, France
The study shows that chimpanzees communicate with each other using hundreds of different sequences, combining up to ten call types across the whole repertoire. This is the first documentation of such a diversity of vocal production in non-human primates. Furthermore, the researchers show that calls – in combination with specific other calls – predictably occurred in certain positions in the sequence, following adjacency rules. These adjacency rules applied also to sequences with three call types.
The team published their findings, open access a few days ago in the journal Communications Biology. In their abstract the authors say:
Copyright: © 2022 The authors.
Published by Springer Nature. Open access. (CC BY 4.0)

The origins of human language remains a major question in evolutionary science. Unique to human language is the capacity to flexibly recombine a limited sound set into words and hierarchical sequences, generating endlessly new sentences. In contrast, sequence production of other animals appears limited, stunting meaning generation potential. However, studies have rarely quantified flexibility and structure of vocal sequence production across the whole repertoire. Here, we used such an approach to examine the structure of vocal sequences in chimpanzees, known to combine calls used singly into longer sequences. Focusing on the structure of vocal sequences, we analysed 4826 recordings of 46 wild adult chimpanzees from Taï National Park. Chimpanzees produced 390 unique vocal sequences. Most vocal units emitted singly were also emitted in two-unit sequences (bigrams), which in turn were embedded into three-unit sequences (trigrams). Bigrams showed positional and transitional regularities within trigrams with certain bigrams predictably occurring in either head or tail positions in trigrams, and predictably co-occurring with specific other units. From a purely structural perspective, the capacity to organize single units into structured sequences offers a versatile system potentially suitable for expansive meaning generation. Further research must show to what extent these structural sequences signal predictable meanings.

The fact that this ability to create complex structures from a range of sounds and so communicate with one another in a coherent way, is strongly suggestive that we both inherited that basic ability from a common ancestor and that the conditions in which we diverged from the chimpanzees are the cause of our more highly evolved ability in this respect.

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