Why Happiness is important

Hi,

I often wonder is happiness an inherent part of human psyche or are we trained to develop and call certain kind of feelings as "happiness", why do we aspire it, why are we not tuned to look for unhappiness, is it possible that if we as kids were not taught to feel those emotions would we have felt them. Do animals fell happy. Do they know whats sadness. Do they do anything to seek happiness.