Design features refer to physiological characteristics that are unique to humans

• The vocal-auditory channel
  • the most widespread form of human communication; many languages have no writing system, but all make use of the vocal-auditory channel
  • acquired first (individuals learn how to speak before they learn how to write, and cultures don't develop written forms of language until after they've developed spoken forms)
  • written language skills are more fragile and vulnerable than speaking/listening skills in the case of brain trauma: it is as if written language is overlayed on top of vocal-auditory abilities (both in individuals and in cultures)
  • the vocal-auditory channel is supported by gaze: the sight line between speaker and listener is important to the communication. Facial expressions affect the message that's received. In evolutionary terms, telephones are extremely recent developments, and are already starting to develop video capabilities, which may suggest that peoples have a desire (perhaps unconscious) to maintain the sight line in a conversation
  • the vocal-auditory channel is supported by gesture. Some gestures are culturally specialised (e.g. mediterranean, asian), but it doesn't seem that there are gestures which are language-specific.
    Some gestures have no apparent connection with the emotion or expression being conveyed; others may be more specific (e.g. drawing pictures in the air with your hands)
  • The sound and nuances of expression in voice can convey information additional to the spoken words, e.g. that the speaker is tired, angry, drunk, etc..
• Biological foundations for language
  • The physiological arrangements for speech seem to have been arrived at by using bits of the anatomy that are there for other reasons, e.g. lungs, windpipe, nose, tongue, oral cavity. See Crystal ch.22
  • in humans, these organs appear to have evolved to make speech possible. But this has disadvantages, e.g. humans occasionally choke on food, whereas in lower primates the arrangement of the larynx makes it almost impossible to do so.
  • The epiglottis, which is like a valve which prevents foreign bodies getting into the lungs, is positioned differently in primates than in humans. In primates, when the epiglottis is closed, it shuts off the path to the mouth, leaving an open path to the nose. In humans, the part of the vocal tract above the epiglottis (the pharynx), is common to both mouth and nose, and so although it acts as a valve above the larynx, it is a lot less effective in preventing foreign bodies entering the lungs. See Trask p.15
• The descent of the larynx
  • It's hard to tell from fossil evidence (since most of the speech organs are soft and don't fossilize well), but evidence suggests that Neanderthal and Rhodesian man share the same "one-tube" system as today's primates: efficient for non-vocal functions but not for speaking.
  • Modern man has a "two-tube" system: the pharynx being at right angles to the oral cavity. This is much more efficient at producing easily distinguishable sounds ("ooo", "aaa" etc.)
  • Humans are born having a "one-tube" system, which means that they cannot make very many different vocal sounds, but that they are at much lower risk of choking. The "descent of the larynx" takes place between 3 and 6 months, when the vocal tract becomes longer and assumes its characteristically human proportions. As a result of this, there is a change in voice quality (and increased danger of choking).
• The descent of language?
  • Historical linguistics attempts to answer the question: are different languages related to each other?
  • The earlist reconstructed language we have is Proto-Indo-European which is thought to have been spoken before 3000BC (see Crystal p288)
  • Most languages in the world are not descended from PIE
  • It is conceivable that all languages are descended from a single common ancestor (long since lost), or that there were multiple unrelated languages which developed independently, which serve as the ancestors for the languages we now know
• Cerebral specialisation
  • The limbic system is the name given to a relatively primitive part of the brain (developed around 100 million years ago), and is common to most mammals, including humans
  • The cerebral cortex developed around 2 million years ago, but only in some mammals
  • Generally speaking, the limbic system is associated for the visceral muscles, such as stomach, heart, which move involuntarily. These also include movements such as sneezing, coughing, laughing
  • The cerebral cortex is more associated with skeletal muscles, that is those which we "decide" to move, such as arms, legs, etc..
  • Noises which are produced under stressful, or emotional conditions, such as cries or calls are thought to be associated with the limbic system
  • It is suggested that the noises produced by animals, such as a warning cry when a predator appears, are precursors to language, although it's difficult to say whether they are equivalent to "words" - does a particular cry represent the word for "lion", or "hide"?
  • Unlike such primitive sounds, human language is voluntary, patterned, and structured into syllables; it is thought to be a function of the more highly developed cortex.
  • The boundary between "emotional" and "cognitive" is blurred though; and examples such as "bouba/kiki" suggest that there may be a link between the limbic/cortex - although it's difficult to argue that all words have some primitive emotional significance