Which way to the dawn of speech?: Reanalyzing half a century of debates and data in light of speech science

Abstract

Recent articles on primate articulatory abilities are revolutionary regarding speech emergence, a crucial aspect of language evolution, by revealing a human-like system of proto-vowels in nonhuman primates and implicitly throughout our hominid ancestry. This article presents both a schematic history and the state of the art in primate vocalization research and its importance for speech emergence. Recent speech research advances allow more incisive comparison of phylogeny and ontogeny and also an illuminating reinterpretation of vintage primate vocalization data. This review produces three major findings. First, even among primates, laryngeal descent is not uniquely human. Second, laryngeal descent is not required to produce contrasting formant patterns in vocalizations. Third, living nonhuman primates produce vocalizations with contrasting formant patterns. Thus, evidence now overwhelmingly refutes the long-standing laryngeal descent theory, which pushes back “the dawn of speech” beyond ~200 ka ago to over ~20 Ma ago, a difference of two orders of magnitude.

Differential DNA methylation of vocal and facial anatomy genes in modern humans

“…because phonetic range is determined by the different configurations that the vocal tract can produce. The roles of divergent anatomy vs. cognition in our speech skills are still debated 45,46 , and some propose that even with a human brain, other apes could not reach the human level of articulation and phonetic range 44,47 . Regardless of its potential role in speech, the process of laryngeal descent is developmentally and evolutionarily associated with facial retraction 48,49 .…”

Semiotics and the Origin of Language in the Lower Palaeolithic

“…From the perspective of quantitative linguistics, the structure of chimpanzee gestures follows mathematical laws seen in the transmission of information in human language linked to frequency of word/gesture use (Heesen et al 2019). The similarities in structure point to commonalities in primate communication that have great evolutionary depth (Boë et al 2019).…”

“…Although there is broad agreement that symbols are crucial to language, there is profound disagreement on what constitutes language, when it evolved and on the interpretation of the material evidence (e.g. Noble and Davidson 1996;Deacon 1997;Corballis 2002;Hauser et al 2002;Everett 2017;Fitch 2017;Boë et al 2019).…”

Chimpanzee lip-smacks confirm primate continuity for speech-rhythm evolution

“…primates (hereafter primates), obscuring the precursors and processes through which our species came to develop a unique and powerful signal system. The last few decades have, however, seen promising new advances (1)(2)(3)(4). A research frontier that has gradually yielded some of the most compelling evidence is the study of the evolutionary origin of speech-rhythm, i.e., the fast open-close mouth cycles characteristic to each and every spoken language in the world (5).…”