Newswise —
Comparable to humans, chimpanzees amalgamate vocalizations into broader communicative units. Researchers from UZH propose that this capacity could be more primitive in evolution than formerly presumed.
An essential characteristic of human language is our aptitude to blend words into more extensive compositional phrases, wherein the significance of the entire is connected to the connotation of the constituents. Nonetheless, the origin or evolution of this capability remains obscure.
Chimpanzees, our nearest extant kin, are recognized to generate multiple distinct vocalizations to handle their social and environmental existence and, in specific situations, merge these vocalizations into more extensive sequences. By performing meticulous, regulated experiments with wild chimpanzees in Uganda, scientists from the University of Zurich (UZH) demonstrated that these combinations are comprehensible to chimpanzees.
Chimpanzees react most strongly to call combinations
Maël Leroux, a postdoctoral scholar at the Department of Comparative Language Science of UZH who spearheaded the research, remarks that "Chimpanzees emit 'alarm-huus' when caught off guard and 'waa-barks' when possibly calling upon conspecifics during aggression or hunting. Our behavioral observations indicate that chimpanzees blend these vocalizations when confronted with a danger where enlisting group members is beneficial, for instance, when stumbling upon a snake. However, experimental validation has been absent up until now."
The scientists exhibited model snakes to chimpanzees and were able to provoke the amalgamated call. Crucially, chimpanzees reacted more strongly to playbacks of the combined call compared to when they heard either "alarm-huu" or "waa-bark" separately. "This is logical since a threat that necessitates group recruitment is a pressing situation and indicates that attentive chimpanzees genuinely blend the significance of the individual vocalizations," explains Simon Townsend, last author of the study and a professor at UZH.
Primate roots of compositionality
A key consequence of the fresh discoveries is that they may reveal the ancestral origins of language's compositional nature. "Around 6 million years ago, humans and chimpanzees diverged from a common ancestor. Therefore, our results suggest that the ability to combine meaningful vocalizations could be at least 6 million years old, or perhaps even older," explained Townsend. Leroux further commented, "These findings offer an intriguing glimpse into the evolutionary emergence of language." In essence, the research suggests that compositionality existed before language itself, but further investigation, ideally with other great ape species, is necessary to validate this claim.
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