Is there a reason why we favor positive emotions over negative emotions?

Simply put unless you are seriously out of balance feeling good gives your body a chemical lift, like serotonin, while feeling bad depresses our systems. Unless your emotions are inverted you would always prefer being lifted up over being brought down. It seem inadequate but feeling good feels good while feeling bad feels bad. It really is that simple. Happiness, fulfillment and satisfaction are the bread of the well balanced man. They feed us while sadness, dis satisfaction and emptiness, makes us feel down and even ill.