ReviewSOCIAL SCIENCES

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

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Science Advances  11 Dec 2019:
Vol. 5, no. 12, eaaw3916
DOI: 10.1126/sciadv.aaw3916

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  • RE: Speech-like monkeys' vocalizations are explained by four articulatory states compatible with Lieberman’s LDT (Figure 1)
    • Frédéric BERTHOMMIER, Researcher, Univ. Grenoble Alpes, CNRS, Grenoble INP, GIPSA-lab, 38000 Grenoble, France

    The DOI given by Figshare at the time of submission of this eLetter for the Figure 1 is corrupted and here is the full link: https://figshare.com/articles/Speech-like_monkey_s_vocalizations_are_exp...

    Fig. 1. The four articulatory states reachable by the vocal tract of monkeys. This panel is drawn with a superposition of acoustic data found by Boë et al. (2017) normalized in the maximal acoustic space and a selection of drawings of the macaque X-ray sagittal views extracted from Fitch et al. (2016). The 5 smooth tube-models having the same F1/F2 resonances as the vowel qualities /u ɔ ɑ ɨ æ/ found by Boë et al. (2017) in baboon’s vocalizations are paired with these drawings in order to show their high degree of similarity. The drawings are also placed similarly around the periphery of the convex hull found for the macaque but not exactly at the same F1/F2 frequencies. We see that the four articulatory states are obtained with elementary mouth and tongue maneuvers (see Hiimae et al., 1995) as following: (1) mouth closed/tongue retraction, (2,2’) mouth opened/tongue retraction, (3) mouth closed/tongue protraction and (4) mouth opened/tongue protraction. A unique tongue-soft palate constriction point is observed in (1) and (2,2’) forming a small pharyngeal cavity having a Helmholtz resonance between 1 and 1.5 k...

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    Competing Interests: None declared.
  • RE: Miocene dawn of speech?
    • Marc Verhaegen, Medical Doctor, Study Center for Anthropology, B-2580 Belgium.

    Thanks a lot for this very interesting paper. Professor Nishimura's team already described Laryngeal Descent versus the hyoid bone in apes (this LD is probably present in all hominoids), but also a hyoidal descent versus the palate (this lowers the larynx still farther), which might be uniquely human among primates. Whereas LD versus the hyoid probably has to do with territorial calls (Darwin already mentioned gibbon song as a preadaptation to human speech), hyoidal descent versus the palate more likely has in the first place to do with deglutition and suction of foods. But this double lowering of the larynx still doesn't explain why only humans developed speech.
    Vaneechoutte et al. (2011) described other biological preadaptations to human speech, which seem to have begun when Pleistocene archaic Homo dispersed intercontinentally, initially along African and southern Eurasian coasts and islands (as far as e.g. Java, China, Flores, Luzon and Sulawesi) where their diet included a lot of littoral foods, which are extremely rich in brain-specific nutrients (esp. docosahexaenoic acid DHA). Seafood not only helps explain the dramatic brain expansion seen in archaic Homo since H. erectus, but also our hyoidal descent, which probably facilitated the deglutition and suction of shell- and crayfish, slippery foods that had to be sucked rather than chewed (this might also explain why Homo lost the masticatory protein MYH-16). Shallow-diving for littoral foods also help...

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    Competing Interests: None declared.
  • RE: Speech-like monkeys' vocalizations are explained by four articulatory states compatible with Lieberman’s LDT
    • Frédéric BERTHOMMIER, Researcher, Univ. Grenoble Alpes, CNRS, Grenoble INP, GIPSA-lab, 38000 Grenoble, France

    Abstract: Large monkey vowel spaces are shown by Boë et al (2019) but these can be explained with a set of 4 articulatory configurations having a limited flexibility. These are the product of ordinary maneuvers of the tongue (protraction, retraction) and mouth (opening, closing) compatible with a high larynx and a flat tongue. Configurations found by Fitch et al. (2016) have been paired with smooth tube models to exhibit these states. An articulatory potential based on a single posterior constriction and just two degrees of freedom is far below human capabilities. Moreover, these limitations are the consequences of either having a high larynx or a flat tongue, and not of the lack of brain control.

    The conclusions made by Boë et al. (2019) about monkey capabilities are based on acoustical observations and they are not constrained by the anatomy. A n-tube model is taken as a reference to outline the F1/F2 maximal acoustic space for a fixed vocal tract length. The acoustical observations are adjusted inside this maximal acoustic space but the underlying tube configurations cannot be used for making causal inferences about the vocal tract states. Then, the anatomical aspects are treated with anthropomorphic articulatory modelling, but at the same time, no clear method is described in the paper for understanding precisely how animal vocal tracts can articulate vowel qualities distinct from the schwa /ə/. To select those configurations having anatomical significance, a di...

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    Competing Interests: None declared.

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