Tuesday, 16 May 2023

Creationism in Crisis - Chimpanzee Vocalization Shows Common Ancestry With Humans

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Chimpanzees form complex vocalisations

© Adrian Soldati
Chimpanzees Combine Calls to Communicate New Meaning | UZH News

Creationists insist that humans were specially created separate from the other mammals as a special type of 'life’ and point to unique characteristics as evidence of this claim, not realising that having unique characteristics is what defines any given species. Elephants, for example, could claim to be a special form of life because they have unique characteristics that distinguish them from, say, giraffes or hyenas.

A unique characteristic of humans often cited by creationists is language - in other words, our ability to combine simple sounds into complex words and words into meaningful sentences. So, it will come as something of a shock to creationists to learn that this ability is not a uniquely human ability and that chimpanzees also have that ability, so it was very probably an ability of the last common ancestor of human and chimpanzees that lives some 6 million years ago.

The discovery was made by a team of researchers led by Maël Leroux of the Department of Comparative Language Science, University of Zürich, Zürich, Switzerland, and including researchers from Utrecht University, Utrecht, Netherlands, the Budongo Conservation Field Station, Masindi, Uganda, the Center for the Interdisciplinary Study of Language Evolution (ISLE), University of Zürich, Zürich, Switzerland, and the Department of Psychology, University of York, York, UK.

Their findings were published open access a few days ago in the journal Nature Communications.

The University of Zurich news release, explains the research and its significance:
Similar to humans, chimpanzees combine vocalizations into larger communicatively meaningful structures. UZH researchers suggest that this ability might be evolutionarily more ancient than previously thought.

A key feature of human language is our ability to combine words into larger compositional phrases i.e., where the meaning of the whole is related to the meaning of the parts. Where this ability came from or how it evolved, however, is less clear.

Chimpanzees, our closest-living relative, are known to produce a number of different vocalizations to manage their social and ecological lives and, under some circumstances, combine these calls into larger sequences. By conducting careful, controlled experiments with wild chimpanzees in Uganda, researchers from the University of Zurich (UZH) showed that these combinations are understood by chimpanzees.

Chimpanzees react most strongly to call combinations

“Chimpanzees produce ‘alarm-huus’ when surprised and ‘waa-barks’ when potentially recruiting conspecifics during aggression or hunting,” says Maël Leroux, a postdoctoral student at the Department of Comparative Language Science of UZH, who led the study. “Our behavioral observations suggest that chimpanzees combine these calls when exposed to a threat where recruiting group members is advantageous, such as when encountering a snake, but until now experimental verification has been missing”.

The researchers presented chimpanzees with model snakes and were able to elicit the call combination. Critically, chimpanzees responded strongest to playbacks of the combination than when hearing either the “alarm-huu” or “waa-bark” alone. “This makes sense because a threat that needs recruitment is an urgent event and suggests listening chimpanzees really are combining the meaning of the individual calls,” adds study last author and UZH professor Simon Townsend.

Primate roots of compositionality

An important implication of the new findings is the potential light they can shed on the evolutionary roots of language’s compositional nature. “Humans and chimpanzees last shared a common ancestor approximately 6 million years ago. Our data therefore indicate that the capacity to combine meaningful vocalizations is potentially at least 6 million years old, if not older,” says Townsend. “These data provide an intriguing glimpse into the evolutionary emergence of language” added Leroux. In a nutshell, it points towards compositionality originating prior to the appearance of language itself, though follow-up observational and experimental work, ideally in other great ape species, will be central to confirming this.
Copyright: © 2023 The authors.
Published by Springer Nature Ltd. Open access. (CC BY 4.0)
In the abstract to their paper, the scientists say:

Through syntax, i.e., the combination of words into larger phrases, language can express a limitless number of messages. Data in great apes, our closest-living relatives, are central to the reconstruction of syntax’s phylogenetic origins, yet are currently lacking. Here, we provide evidence for syntactic-like structuring in chimpanzee communication. Chimpanzees produce “alarm-huus” when surprised and “waa-barks” when potentially recruiting conspecifics during aggression or hunting. Anecdotal data suggested chimpanzees combine these calls specifically when encountering snakes. Using snake presentations, we confirm call combinations are produced when individuals encounter snakes and find that more individuals join the caller after hearing the combination. To test the meaning-bearing nature of the call combination, we use playbacks of artificially-constructed call combinations and both independent calls. Chimpanzees react most strongly to call combinations, showing longer looking responses, compared with both independent calls. We propose the “alarm-huu + waa-bark” represents a compositional syntactic-like structure, where the meaning of the call combination is derived from the meaning of its parts. Our work suggests that compositional structures may not have evolved de novo in the human lineage, but that the cognitive building-blocks facilitating syntax may have been present in our last common ancestor with chimpanzees.

Fig. 1: Number of recruited individuals according to the production of the call combination.
yes: the subject produced an “alarm-huu + waa-bark” combination upon the discovery of the snake; no: the subject did not produce an “alarm-huu + waa-bark” combination upon the discovery of the snake. Red dots show the raw data. The boxes display the median value and 25 and 75% quartiles; the whiskers are extended to the most extreme value inside the 1.5-fold interquartile range. Trials = 21, individuals = 13. Source data are provided as a Source Data file.

So, more creationist core beliefs come tumbling down as science reveals more facts about the world. What was thought to be a uniquely human ability that arose without ancestry, like creationists believe humans did, turns out to be just a more highly developed ability that was present in an ancestral species at least 6 million years ago.

And again, the scientists show no doubt that humans and chimpanzees have evolved from the common ancestor, with no hint that they believe special creation by magic is a better explanation of the facts. If any more confirmation were needed, papers like this simply add to the body of evidence that the Theory of Evolution is the 'Grand Unifying Theory' of biology, underpinning all of our understanding of biology, biodiversity and phylogeny.

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