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Hand Surgery Department of Clinical Sciences, Malmö Lund University Skäne University Hospital, Malmö, Sweden
Abstract
Hands and arms are important components of communication and interaction among individuals. From an evolutionary perspective, bipedalism made it possible to use the hands for communication by gestures and signs long before there was a spoken language. Speech as well as hand/arm movements are associated with the activation of Broca’s area in the left frontal cortex, and it appears that Broca’s area is involved in the organisation of speech as well as hand movements. In our normal body language and our communication with other individuals, gestures and hand movements are linked to speech in a natural way, reflecting overlapping representational areas of these functions in Broca’s area. The gene FOXP2, necessary for coordination of tongue and lip movements in a spoken language, seems largely to have appeared in the last 200,000 years of human development. Thus, the conditions necessary for fully developed speech seem to be have appeared late in the evolutionary process, about the time our own species, Homo sapiens, emerged.
A unique human trait is the ability to communicate using a spoken language, creating a basis for our social life and giving our culture a special dimension. When we speak we can formulate, express and convey thoughts and ideas in our communication with others. The benefits of a spoken language are enormous. Sound has few limitations and can be transmitted around corners and over large distances. It is not suppressed by darkness, and it does not require eye contact with the person being addressed. The ability to articulate and to vary the volume and pitch of the voice introduced great potential for high precision in verbal communication.
The arms and hands also play an important role in communicating with other individuals. Signs and gestures are obvious and natural complements to the spoken language. It seems that talking and hand/arm movements are integrated and inseparable components in our communication with others.
How did our earliest ancestors communicate with each other? How and when during evolution did the spoken articulated language emerge? Today we know that there are several requirements for making an articulated vocal language possible. The brain must be sufficiently well developed for abstract and symbolic thinking to occur, which is necessary to make a spoken language possible. Appropriate anatomical conditions must be there to make possible the production of precise and meaningful sounds. Also, the larynx and the vocal cords must have the right anatomical structures and be positioned correctly, and they must have a sufficient nerve supply. In addition, there must be an ability to control breathing with rapid inhaling and slow exhaling, making the vocal cords vibrate appropriately.
Such conditions were first present late in the evolutionary process. So how did our early ancestors communicate with each other? Probably by using gestures, facial expressions and simple sounds, perhaps unarticulated grunts. There are strong indications that human language in fact emerged from body language, especially from gestures of the hands and facial expressions, and that the first language in fact was a language of gestures – a primitive sign language.
In his book From Hand to Mouth, Corballis argues that human language was initially based on gestures rather than sounds and that bipedalism and upright walking were important steps in making a language of gestures possible – a signed language where the free arms and hands allowed gestures, signs and hand movements [1]. A language based on gestures and signs is in fact very rich in expressions; yet it is simple and does not require complicated anatomical structures for sound generation.
A signed language can have many advantages: one can use it to avoid detection – gestures are silent while speaking is easy for enemies to hear. The hand can easily indicate directions and objects and point out phenomena in the environment. In addition, it is easy to indicate the size and shape of objects using the hands. A newborn child points before it is able to speak. All of us gesticulate while we are talking; the hand is often described as an important organ for communication. The modern sign language of the deaf and people with impaired hearing is rich and complete and can, in some respects, have several advantages over spoken language [2].
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