"It remains true, as every paleontologist knows, that most new species, genera, and families, and that nearly all categories above the level of families, appear in the record suddenly and are not led up to by known, gradual completely continuous transitional sequences."

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The mechanism of primary emotions does not describe the full range of emotional behaviors. They are, to be sure, the basic mechanism. However, I believe that in terms of an individual's development they are followed by mechanisms of secondary emotions, which occur once we begin experiencing feelings and forming systematic connections between categories of objects and situations, on the one hand, and primary emotions, on the other.

— Antonio Damasio