PHYSICAL ADAPTATION SOURCE

PHYSICAL ADAPTATION SOURCE

 Instead of looking at types of sounds as the source of human speech, we can look at the types of physical features humans possess, especially those that are distinct from other creatures, which may have been able to support speech production. We can start with the observation that, at some early stage, our ancestors made a very significant transition to an upright posture, with bipedal (on two feet) locomotion, and a revised role for the front limbs.Some effects of this type of change can be seen in physical differences between the skull of a gorilla and that of a Neanderthal man from around 60,000 years ago. The reconstructed vocal tract of a Neanderthal suggests that some consonant-like sound distinctions would have been possible. We have to wait until about 35,000 years ago for features in reconstructions of fossilized skeletal structures that begin to resemble those of modern humans. In the study of evolutionary development, there are certain physical features, best thought of as partial adaptations, which appear to be relevant for speech. They are streamlined versions of features found in other primates. By themselves, such features would not necessarily lead to speech production, but they are good clues that a creature possessing such features probably has the capacity for speech.

TEETH AND LIPS

Human teeth are upright, not slanting outwards like those of apes, and they are roughly even in height . They are also much smaller. Such characteristics are not very useful for ripping or tearing food and seem better adapted for grinding and shewing. They are also very helpful in making sound such as v. Human lips have much more intricate muscle interlacing than is found in other primates and their resulting flexibility certainly helps in making sounds like p, b and m. In fact , the b and m sounds are the most widely attested in the vocalizations made by human infants during their first year, no matter which language their parents are using.

MOUTH AND TONGUE

The human mouth is relatively small compare to other primates and can be opened and closed rapidly. It is also  part of in extended vocal tact that has some of an L-shape than the straight path from front to back in other mammals. In contrast to the fairly thin flat tongue of other large primates, human have a shorter, thicker and more muscular tongue that can be used to shape a wide variety of sounds inside the oral cavity. In addition, unlike other primates, humans can close off airway through nose to create more air pressure in the mouth. The overall effect of all these differences taken together is a face with more intricate muscle interlacing in the lips and mouth, capable of a wider range of shapes and a more rapid and powerful delivery of sounds produced through these different shapes.

LARYNX AND PHARYNX

The human larynx or “voice box” (containing the vocal folds or vocal cords) differs significantly in position from the larynx of other primates such as monkeys. In the course of human physical development, the assumption of an upright posture moved the head more directly above the spinal column and the larynx dropped to a lower position. This created a longer cavity called the pharynx, above the vocal folds, which acts as a resonator for increased range and clarity of the sounds produced via the larynx and the vocal tract. One unfortunate consequence of this development is that the lower position of the human larynx makes it much more possible for the human to choke on pieces of food.d. Monkeys may not be able to use their larynx to produce speech sounds, but they do not suffer from the problem of getting food stuck in their windpipe. In evolutionary terms, there must t have been a big advantage in getting this extra vocal power (i.e. a larger range of sound distinctions) to outweigh the potential disadvantage from an increased risk of choking to death.