Send social signals - Facial expressions are often more accurate than words.
Help us to adapt & survive - This is the psychoevolutionary theory of emotions. They help us adapt because they signal intentions to others & vise versa.
Arouse & motivate us - According to the Yerkes-Dodson law the more complex the task, the lower the level of emotional arousal that can be tolerated without interfering with performance.
Happiness is an agreeable feeling or condition of the soul arising from good fortune or propitious happening of any kind; the possession of those circumstances or that state of being which is attended enjoyment; the state of being happy; contentment; joyful satisfaction; felicity; blessedness. It is not an entitlement.
Adaptation Level Theory indicates that what we have
(our present state of being) we adapt to & therefore what we have does not influences long-term happiness.
There are genetic (inherited) differences in happiness. People have different happiness set points.
Emotional intelligence is a type of social intelligence that involves the ability to monitor one's own & others' emotions, to discriminate among them, and to use the information to guide one's thinking & actions.
Showing emotions are governed by cultural display rules.
Lie Detector results are not allowed in courts nor are the results reliable.