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Guido Guido
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7 years ago
Smiling when happy seems to be an expression common to all human societies, suggesting that this behavior is probably
A) genetic in origin.
B) learned.
C) altruistic.
D) based on social standing.
Textbook 
Biology: Life on Earth

Biology: Life on Earth


Edition: 10th
Authors:
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skeledentskeledent
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7 years ago
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Guido Author
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7 years ago
You make an excellent tutor!
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Thanks for your help!!
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