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1. True language��the spoken languages used by most people and the gestural languages used by the deaf��does not have to be taught in special classes.
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2. Sign language is a visual/gestural language that serves as the primary means of communication for deaf individuals, just as spoken languages are used among the hearing.
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3. This finding bolsters the so-called gestural theory of language evolution, whose proponents argue that language evolved initially as a gesture system before becoming vocal.
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gestural language
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