Section 1 the lay of the land an overview of

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section 1 The lay of the land: an overview of disciplines and data relevant to language evolution 1 Language from a biological perspective
On an autumn day in 1947, much like any other, Cathy and Keith Hayes returned to their suburban American ranch house with their newborn infant girl, Viki (Hayes, 1951 ). After a few difficult days, Viki began feeding well and growing rapidly. She was a very quiet baby, sweet and affectionate, and loved to be held and tickled. She learned to walk early, entering a rambunc tious phase and breaking numerous household objects, but eventually her loving parents’ gentle discipline bore fruit and she developed into a playful, obedient little girl. By the age of three, Viki could feed and bathe herself, eat with a spoon and drink through a straw, and help with cleaning. She was fond of looking at herself in the mirror, and loved assembling jigsaw puzzles. She enjoyed playing on the backyard swing, climbing trees, and playing peekaboo with the neighborhood children. She was in many ways a normal young girl, with one major exception: Viki did not speak. Not a word. She was able to grunt, scream, and laugh, so her problem was not with vocalization in general; instead it seemed to stem from a neural dif ficulty specific to spoken language. After consultation with experts, Cathy Hayes instituted a speech training regime, manipulating her young pupil’s lips manually and rewarding her with treats whenever she approximated a word. Unfortunately, even these dedicated efforts were mostly in vain: Viki’s “vocabulary” reached a plateau of three words ( mama , papa , and cup ), and even these attempts were breathy and inarticulate: poor imitations of normal English speech. Viki seemed tragically doomed to a life without speech. Fortunately, Viki’s parents were not totally surprised or alarmed by her failure to achieve speech or language, because Viki was a chimpanzee. Chimpanzees are the closest living species to humans. Chimpanzees are closer to humans, in genetic and evolutionary terms, than they are to goril las or other apes. The fact that a chimpanzee will not acquire speech, even when raised in a human home with all the environmental input of a normal human child, is one of the central puzzles we face when contemplating the biology of our species. For every normal child, anywhere in the world, will rapidly acquire the native language, or languages, in their local environ ment, and will do so even in the face of social, nutritional,
and intellectual adversity far more severe than any difficulties Viki faced as an adopted child 14 Language from a biological perspective in her suburban home. In repeated experiments, starting in the 1910s, chim panzees raised in close contact with humans have universally failed to speak, or even to try to speak, despite their rapid progress in many other intellec tual and motor domains (Yerkes and Yerkes, 1929 ). This fact was already clear by the 1960s, and is undisputed by modern scientists, but the under lying reasons for this apparent inability remain contested even today.

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