Phonetic potential in the extant apes and extinct hominins

QC 20240805

Abstract

Several novel claims with bearing on the evolution of speech production are made. It is shown through a series of theoretical, empirical, and computational works that the vocal anatomy of non-human apes, such as gibbons, orangutans, and chimpanzees, allows for the production of variable vowel-like contrasts. These phenomena in extant nonhuman primates are likely consistent with the animals’ retracting the tongue, potentially homologous with aspects of speech production. However, relationships of biomechanics inherent to the primate vocal production apparatus render fluid speech unrealistic. The articulatory configurations necessary to achieve these contrasts likely recruit lingual gestures disparate to those of humans, reflecting disparate anatomy. Novel evidence is also presented, illustrating elementary vocal production learning capacities in chimpanzees. These capacities are thus unlikely to have emerged de novo in our lineage. Building on these two sources of evidence, the evolution of speech is not straightforwardly reducible to “neural evolution”. Rather, additional evolutionary pressures must have acted upon hominin ancestors to ultimately trigger the evolution of spoken language. Toward this end, paleoanthropological evidence of articulator evolution in the hominin lineage is explored. The introduction of increasingly complex food processing and tool use, typically argued to have led to widespread anatomical changes in the face and guts of human ancestors, appear simultaneously with changes on the hominin would-be articulatory complex. Potential articulatory benefits of these changes in ancestral hominins are explored. An efficient articulatory apparatus, and the neural substrates by which to efficiently control it, likely evolved simultaneously with the human genus itself.  

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