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5.2: Biological Basis of Language and Language Aquisition

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    The human anatomy that allowed the development of language emerged six to seven million years ago when the first human ancestors became bipedal—habitually walking on two feet. Most other mammals are quadrupedal—they move about on four feet. This evolutionary development freed up the forelimbs of human ancestors for other activities, such as carrying items and doing more and more complex things with their hands. It also started a chain of anatomical adaptations. One adaptation was a change in the way the skull was placed on the spine. The skull of quadrupedal animals is attached to the spine at the back of the skull because the head is thrust forward. With the new upright bipedal position of pre-humans, the attachment to the spine moved toward the center of the base of the skull. This skeletal change in turn brought about changes in the shape and position of the mouth and throat anatomy.

    Diagram of Human Articulatory Anatomy
    Figure \(\PageIndex{1}\): Human Articulatory Anatomy

    Humans have all the same organs in the mouth and throat that the other great apes have, but the larynx, or voice box (you may know it as the Adam’s apple), is in a lower position in the throat in humans. This creates a longer pharynx, or throat cavity, which functions as a resonating and amplifying chamber for the speech sounds emitted by the larynx. The rounding of the shape of the tongue and palate, or the roof of the mouth, enables humans to make a greater variety of sounds than any great ape is capable of making (see Figure 5.2.1).

    Speech is produced by exhaling air from the lungs, which passes through the larynx. The voice is created by the vibration of the vocal folds in the larynx when they are pulled tightly together, leaving a narrow slit for the air to pass through under pressure. The narrower the slit, the higher the pitch of the sound produced. The sound waves in the exhaled air pass through the pharynx then out through the mouth and/or the nose. The different positions and movements of the articulators—the tongue, the lips, the jaw—produce the different speech sounds.

    Along with the changes in mouth and throat anatomy that made speech possible came a gradual enlargement and compartmentalization of the brain of human ancestors over millions of years. The modern human brain is among the largest, in proportion to body size, of all animals. This development was crucial to language ability because a tremendous amount of brain power is required to process, store, produce, and comprehend the complex system of any human language and its associated culture. In addition, two areas in the left brain are specifically dedicated to the processing of language; no other species has them. They are Broca’s area in the left frontal lobe near the temple, and Wernicke’s area, in the temporal lobe just behind the left ear.


    Linguist Noam Chomsky proposed that all languages share the properties of what he called Universal Grammar (UG), a basic template for all human languages, which he believed was embedded in our genes, hard-wiring the brains of all human children to acquire language. Although the theory of UG is somewhat controversial, it is a fact that all normally developing human infants have an innate ability to acquire the language or languages used around them. Without any formal instruction, children easily acquire the sounds, words, grammatical rules, and appropriate social functions of the language(s) that surround them. They master the basics by about age three or four. This also applies to children, both deaf and hearing, who are exposed to signed language.

    Definition: Universal Grammar (UG)

    A theory developed by linguist Noam Chomsky suggesting that a basic template for all human languages is embedded in our genes.

    If a child is not surrounded by people who are using a language, that child will gradually lose the ability to acquire language naturally without effort. If this deprivation continues until puberty, the child will no longer be biologically capable of attaining native fluency in any language, although they might be able to achieve a limited competency. This phenomenon has been called the Critical Age Range Hypothesis. A number of abused children who were isolated from language input until they were past puberty provide stark evidence to support this hypothesis. The classic case of “Genie” is an example of this evidence.[1]

    Definition: Critical Age Range Hypothesis

    Research suggesting that a child will gradually lose the ability to acquire language naturally and without effort, if he or she is not exposed to other people speaking a language until past the age of puberty. This applies to the acquisition of a second language as well.

    Found at the age of almost 14, Genie had been confined for all of her life to her room and, since the age of two, had been tied to a potty chair during the day and to a crib at night with almost no verbal interaction and only minimal attention to her physical needs. After her rescue, a linguist worked with her intensively for about five years in an attempt to help her learn to talk, but she never achieved language competence beyond that of a two-year old child. The hypothesis also applies to the acquisition of a second language. A person who starts the study of another language after puberty will have to exert a great deal of effort and will rarely achieve native fluency, especially in pronunciation. There is plenty of evidence for this in the U.S. educational system. You might very well have had this same experience. It makes you wonder why our schools rarely offer foreign language classes before the junior high school level.


    1. You can find a documentary film about Genie via Google or YouTube under the title Genie, Secret of the Wild Child, a NOVA production.

    Adapted From

    "Language" by Linda Light, California State University. In Perspectives: An Open Invitation to Cultural Anthropology, 2nd Edition, Society for Anthropology in Community Colleges, 2020, under CC BY-NC 4.0.

    5.2: Biological Basis of Language and Language Aquisition is shared under a CC BY-NC license and was authored, remixed, and/or curated by LibreTexts.