1. Animal: The signs of animal systems are inborn.
Human: The capacity to be creative with signs is inborn,
but the signs (words) themselves are acquired culturally.
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2. Animal: Communication is set responses to stimuli (indexes).
Human: Not limited to use as an index.
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3. Animal: Each sign has one and only one function; each meaning can be expressed only in one way
Human: Signs often have multiple functions; one meaning can be expresses in many ways
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4. Animal: Not naturally used in novel way
Human: Creative, can be adapted to new situations
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5. Animal: Closed inventory of signs; only a set number of different messages can be sent
Human: Open ended. Grammar (rules of syntax) allows a virtually unlimited number of messages to be constructed
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6. Animal: Change extremely slowly, with the speed of genetic evolution.
Human: Change rapidly as a cultural phenomenon.