Let me take you on a walking tour through the gardens of philosophy, psychology, neuroscience, not to mention popular culture. It's just a three minutes walk that you won't regret.
Emotions are an evolutionary necessity that plays an essential role in ensuring human survival. Some basic emotions seem to be hard-wired into our human species, innate and invariable, notwithstanding cultural differences. In example, fear and anger have helped human survival by encouraging reflexive flight and hard fighting.