Emotions:

The Subtlety of Emotions, Aaron Ben-Ze'ev, 2001:

"One basic evolutionary function of emotions is indeed that of immediate mobilization. This function enables us to regulate the timing and locus of investment in the sense of allocating resources away from situations where they would be wasted, and toward those where investment will yield a significant payoff. Low intensity of the feeling dimension, as well as of other mental components, usually expresses neutral or indifferent states of the mental system."