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Abstract: This paper considers first the concepts of temperament and emotion and then describes some of the genetic and neurochemical correlates of varied temperamental biases and their contribution to emotions. This discussion is followed by a detailed description of the infant temperamental biases called high- and low-reactive to unfamiliarity and their derivatives across the first 15 years of life. The essay ends with a discussion of the possibility of temperamental differences among reproductively isolated populations.
Keywords: temperament, reactivity, fear, amygdala, social anxiety