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Comparative morphology of the hyo-laryngeal complex in anthropoids: two steps in the evolution of the descent of the larynx.
Primates. 2003 Jan; 44(1):41-9.P

Abstract

The descent of the larynx is a key phenomenon not only in postnatal development, but also in the evolution of human speech. The positional change of the larynx is affected by the descent of the hyoid bone in relation to the mandible and cranial base, and that of the laryngeal framework in relation to the hyoid bone. The phylogeny of the spatial configuration of the hyo-laryngeal complex is one of the most important sources of information for elucidating the evolution of laryngeal descent. In the present study, the anatomy of the complex was examined in various species of anthropoids to compare the configuration, the shape of the basihyal and thyroid cartilage, and the length of the lateral thyrohyoid ligaments. Non-human hominoids share most features with humans, while cercopithecoids and ceboids have anatomical features that sharply contrast to humans, except for the form of the thyroid cartilage in ceboids. The laryngeal framework in hominoids is well separated from and assured of mobility independent of the hyoid. In cercopithecoids and ceboids, it is, by contrast, locked into and tied tightly with the hyoid so that the hyo-laryngeal complex acts as a functional unit. This spatial configuration is considered to be significantly related to the mechanism that prevents aspiration, including epiglottic movement and vestibular closure. Non-human hominoids are inferred to share the mechanism with human adults, not with cercopithecoids and ceboids, although their larynx is located as high as the latter. Consequently, it is hypothesized that the descent of the larynx evolved in two steps. The first step would have been descent of the thyroid in relation to the hyoid for the evolution of the mechanism preventing aspiration, which occurred in the common ancestor of hominoids. The second step, descent of the hyoid within the neck, occurred during hominid evolution for human speech.

Authors+Show Affiliations

Primate Research Institute, Kyoto University, 41 Kanrin, Inuyama, Aichi 484-8506, Japan. nishimur@pri.kyoto-u.ac.jp

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

12548333

Citation

Nishimura, Takeshi. "Comparative Morphology of the Hyo-laryngeal Complex in Anthropoids: Two Steps in the Evolution of the Descent of the Larynx." Primates; Journal of Primatology, vol. 44, no. 1, 2003, pp. 41-9.
Nishimura T. Comparative morphology of the hyo-laryngeal complex in anthropoids: two steps in the evolution of the descent of the larynx. Primates. 2003;44(1):41-9.
Nishimura, T. (2003). Comparative morphology of the hyo-laryngeal complex in anthropoids: two steps in the evolution of the descent of the larynx. Primates; Journal of Primatology, 44(1), 41-9.
Nishimura T. Comparative Morphology of the Hyo-laryngeal Complex in Anthropoids: Two Steps in the Evolution of the Descent of the Larynx. Primates. 2003;44(1):41-9. PubMed PMID: 12548333.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Comparative morphology of the hyo-laryngeal complex in anthropoids: two steps in the evolution of the descent of the larynx. A1 - Nishimura,Takeshi, Y1 - 2002/11/22/ PY - 2002/01/27/received PY - 2002/08/27/accepted PY - 2003/1/28/pubmed PY - 2003/6/11/medline PY - 2003/1/28/entrez SP - 41 EP - 9 JF - Primates; journal of primatology JO - Primates VL - 44 IS - 1 N2 - The descent of the larynx is a key phenomenon not only in postnatal development, but also in the evolution of human speech. The positional change of the larynx is affected by the descent of the hyoid bone in relation to the mandible and cranial base, and that of the laryngeal framework in relation to the hyoid bone. The phylogeny of the spatial configuration of the hyo-laryngeal complex is one of the most important sources of information for elucidating the evolution of laryngeal descent. In the present study, the anatomy of the complex was examined in various species of anthropoids to compare the configuration, the shape of the basihyal and thyroid cartilage, and the length of the lateral thyrohyoid ligaments. Non-human hominoids share most features with humans, while cercopithecoids and ceboids have anatomical features that sharply contrast to humans, except for the form of the thyroid cartilage in ceboids. The laryngeal framework in hominoids is well separated from and assured of mobility independent of the hyoid. In cercopithecoids and ceboids, it is, by contrast, locked into and tied tightly with the hyoid so that the hyo-laryngeal complex acts as a functional unit. This spatial configuration is considered to be significantly related to the mechanism that prevents aspiration, including epiglottic movement and vestibular closure. Non-human hominoids are inferred to share the mechanism with human adults, not with cercopithecoids and ceboids, although their larynx is located as high as the latter. Consequently, it is hypothesized that the descent of the larynx evolved in two steps. The first step would have been descent of the thyroid in relation to the hyoid for the evolution of the mechanism preventing aspiration, which occurred in the common ancestor of hominoids. The second step, descent of the hyoid within the neck, occurred during hominid evolution for human speech. SN - 0032-8332 UR - https://www.unboundmedicine.com/medline/citation/12548333/Comparative_morphology_of_the_hyo_laryngeal_complex_in_anthropoids:_two_steps_in_the_evolution_of_the_descent_of_the_larynx_ L2 - https://dx.doi.org/10.1007/s10329-002-0005-9 DB - PRIME DP - Unbound Medicine ER -