Infants show a lot of variability in their temperament, or their characteristic mood, activity level, and emotional activity. From the beginning of life, some babies seem very outgoing and willing to conform the demands of the outside. On the other side of the coin, some babies seemed to have perfered the peace of the mother, and seem to be cranky, irritable and not willing to participate in their new environment. Temperaments, like emotion in the evolutionary since, evolved to allow greater survivability in the human species.
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