The relation between the larynx, pharynx, and oral cavity changed. Bipedalismīipedalism resulted in a series of adaptive phenomena that would later contribute to the appearance of the spoken language. In addition to language three conditioning factors could have influenced the development and evolution of the hard structures relating to the oral cavity of modern man: bipedalism, oral habits, and genetics. The working hypothesis of this study is that the bone structures that participate in phonatory function have evolved conditioned among other factors to the specific movements of spoken language, and with the purpose of facilitating such movements.īy studying the bone structures of the temporomandibular joints (mandibular condyle and articular tubercle of the temporal bone), the bone structures surrounding the tongue (alveolar process, mandible, and hard palate) and the hard structures related to the lower lip (chin and its inclinations), it may be possible to establish associations with speech. human facial bones.Īlthough the difference in body mass between humans and chimpanzees is always in favor of humans, the maxillofacial massif appears larger and more prominent in chimpanzees. The present study involves a comparative anatomical investigation of chimpanzee facial bones vs. Mammals have had a larynx, pharynx, and oral cavity for many millions of years and these structures allow the different species to communicate. In effect, speech is a characteristic exclusive to Homo sapiens, though the human phonatory apparatus is not a specific organ. “Of all animals, only Man possesses speech” (Aristotle). This leads to the conclusion that, at least in part, speech is behind all these changes, although it is difficult to establish a cause-effect relationship. There is a greater lingual space and there is also a chin that suggests a muscular stimulant. The human skull has temporomandibular joints that are comparatively less flat with a more limited movement. The refinement of the supralaryngeal vocal tract in the human species must have co-evolved with speech fairly recently. However, the majority of the variables studied in skulls and mandibles are greater in chimpanzees, which suggests that the evolution of the oral zone in humans has suffered a reduction in size with changes in shape. On average, humans weigh 70 kg and chimpanzees 44 kg. The number of mandibular movements involved in speech is far greater than those used in chewing, which must have conditioned the evolution of the oral structures implicated in the development of language. Together with other factors (bipedalism, habits, and genetics) speech in humans must have played an important role in the aforementioned differences between humans and chimpanzees. This has been confirmed with the analysis of new variables. The chin, which is unique to the human species, is quantified through the external slope of the mandibular symphysis with a lesser angle in humans.ĭiscussion: It is obvious that there are differences between humans and chimpanzees in the bone morphology of the oral cavity structures. A significant difference is noted in mandibular alveolar vergency and in the internal slope of the mandibular symphysis where the oral cavity’s morphology is modified, thereby increasing the free space for tongue movements in humans. The human temporomandibular joint is comparatively less flat and has a more limited excursive movement range, with structural elements that seem to be lighter. Results: A number of highly significant differences were found between humans and chimpanzees. Materials and Methods: Twenty dry skulls and 20 mandibles of modern Caucasians were compared with 12 dry skulls and 12 mandibles of chimpanzees, with the analysis of 37 variables and the definition of new anatomical parameters. The possible changes have been evaluated by comparing two close species essentially differentiated from each other by spoken language. Objectives: The present study explores the hypothesis that the anatomical bone structures of the oral cavity have probably evolved under the influence of language function.
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