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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.

    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 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.

    Language Acquisition in Childhood

    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.

    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 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.

    The Gesture Call System and Non-Verbal Human Communication

    All animals communicate and many animals make meaningful sounds. Others use visual signs, such as facial expressions, color changes, body postures and movements, light (fireflies), or electricity (some eels). Many use the sense of smell and the sense of touch. Most animals use a combination of two or more of these systems in their communication, but their systems are closed systems in that they cannot create new meanings or messages. Human communication is an open system that can easily create new meanings and messages. Most animal communication systems are basically innate; they do not have to learn them, but some species’ systems entail a certain amount of learning. For example, songbirds have the innate ability to produce the typical songs of their species, but most of them must be taught how to do it by older birds.

    Great apes and other primates have relatively complex systems of communication that use varying combinations of sound, body language, scent, facial expression, and touch. Their systems have therefore been referred to as a gesture-call system. Humans share a number of forms of this gesture-call, or non-verbal system with the great apes. Spoken language undoubtedly evolved embedded within it. All human cultures have not only verbal languages, but also non-verbal systems that are consistent with their verbal languages and cultures and vary from one culture to another. We will discuss the three most important human non-verbal communication systems.


    Kinesics is the term used to designate all forms of human body language, including gestures, body position and movement, facial expressions, and eye contact. Although all humans can potentially perform these in the same way, different cultures may have different rules about how to use them. For example, eye contact for Americans is highly valued as a way to show we are paying attention and as a means of showing respect. But for the Japanese, eye contact is usually inappropriate, especially between two people of different social statuses. The lower status person must look down and avoid eye contact to show respect for the higher status person.

    Facial expressions can convey a host of messages, usually related to the person’s attitude or emotional state. Hand gestures may convey unconscious messages, or constitute deliberate messages that can replace or emphasize verbal ones.


    Proxemics is the study of the social use of space, specifically the distance an individual tries to maintain around himself in interactions with others. The size of the “space bubble” depends on a number of social factors, including the relationship between the two people, their relative status, their gender and age, their current attitude toward each other, and above all their culture. In some cultures, such as in Brazil, people typically interact in a relatively close physical space, usually along with a lot of touching. Other cultures, like the Japanese, prefer to maintain a greater distance with a minimum amount of touching or none at all. If one person stands too far away from the other according to cultural standards, it might convey the message of emotional distance. If a person invades the culturally recognized space bubble of another, it could mean a threat. Or, it might show a desire for a closer relationship. It all depends on who is involved.


    Paralanguage refers to those characteristics of speech beyond the actual words spoken. These include the features that are inherent to all speech: pitch, loudness, and tempo or duration of the sounds. Varying pitch can convey any number of messages: a question, sarcasm, defiance, surprise, confidence or lack of it, impatience, and many other often subtle connotations. An utterance that is shouted at close range usually conveys an emotional element, such as anger or urgency. A word or syllable that is held for an undue amount of time can intensify the impact of that word. For example, compare “It’s beautiful” versus It’s beauuuuu-tiful!” Often the latter type of expression is further emphasized by extra loudness of the syllable, and perhaps higher pitch; all can serve to make a part of the utterance more important. Other paralinguistic features that often accompany speech might be a chuckle, a sigh or sob, deliberate throat clearing, and many other non-verbal sounds like “hm,” “oh,” “ah,” and “um.”

    Most non-verbal behaviors are unconsciously performed and not noticed unless someone violates the cultural standards for them. In fact, a deliberate violation itself can convey meaning. Other non-verbal behaviors are done consciously like the U.S. gestures that indicate approval, such as thumbs up, or making a circle with your thumb and forefinger—“OK.” Other examples are waving at someone or putting a forefinger to your lips to quiet another person. Many of these deliberate gestures have different meanings (or no meaning at all) in other cultures. For example, the gestures of approval in U.S. culture mentioned above may be obscene or negative gestures in another culture.

    Exercise \(\PageIndex{1}\)

    Try this: As an experiment in the power of non-verbal communication, try violating one of the cultural rules for proxemics or eye contact with a person you know. Choosing your “guinea pigs” carefully (they might get mad at you!), try standing or sitting a little closer or farther away from them than you usually would for a period of time, until they notice (and they will notice). Or, you could choose to give them a bit too much eye contact, or too little, while you are conversing with them. Note how they react to your behavior and how long it takes them to notice.