Again, no expert here. But this is how my therapist described it to me (paraphrasing and all mistakes are purely my own).
Why do we get angry? When an animal is threatened, there are three choices: Fight, Flight, Freeze.
Threat = fear. When we feel threatened, fear of what will happen in the future is it's root. Anger is a survival tactic developed to cope with threats.
So now let's look at the Fight/Flight response.
- Fight. When you or someone you are protecting is threatened, you choose (or have no choice) to fight. When this happens, your brain hides your fear from you by creating anger. It does this by pumping adrenaline and other chemicals into your system. These chemicals flood your system, make you stronger, reduce pain, etc., so that you can fight better.
- Flight. Run away! When you feel fear, the best protection is to remove yourself from the situation. The same chemicals above also allow you to run faster and be more perceptive of dangers.
- Freeze. Sometimes animals that sense danger freeze in place. This has two effects: If they sense a predator and they stand perfectly still, maybe the predator won't see them. Or when their brain starts flooding their body with chemicals, their system is overwhelmed and shuts down.
Anger is a response to fear. When you feel angry, it's because you feel fear. That fear can be obvious — you are being mugged. That fear can be hidden — something happened that you subconsciously determined was a threat. When we are angry, most people can't see their own fear, because anger is designed to hide fear!
Our biology is still driven by instinctive level responses. Pheromones that we aren't conscious of, still signal our bodies its mating time. Similarly we are instinctively always on the lookout for threats. We often see threats even when none exist and our body responds. If there is no threat, then you have generated inappropriate anger. You get angry to hide some kind of fear (fear of looking weak, fear of looking stupid, fear that someone will "get away with something they shouldn't", fear that your partner will leave you).
My therapist believes that the ultimate goal of therapy is to put your rational mind back in charge of your primitive mind. To this end you have to understand what your fears are (hidden and overt) and to learn to understand your instinctive responses so that you stop reacting automatically and inappropriately.
All that being said, I'm a loooong way from her goal. So, 1,000 jumping jacks. By the four-count. Ready? Begin.