More than 2300 years ago, Aristotle said, "Anyone can get angry, that is easy. But to be angry with the right person, at the right time, for the right reason, and in the right way - that is not easy."
As rational individuals, we all know that there are times when we are unreasonable in getting angry at someone. Why then, do we do it? We blame it on tough living conditions, stress on the job, family stress, and of course, the most common reason - PMS! Point being, we tend to blame our behaviour on our surroundings, external conditions, etc - basically, everything other than our own behavioural deficiencies.
What then, prompted Aristotle to say this more than two thousand years ago? A time, when, presumably, the stress in life was far lesser, lifestyles were simpler, more minimalistic and jobs were certainly less stressful (unless you were a soldier, of course!). The fact is, that whatever situation we are in, in life, a majority of us find it difficult to get by - we fancy our neighbour's pie more than our own, and tend to feel victimised when life hands us the proverbial lemon.
This would mean that, in the last 2000 years, as a race, human beings haven't evolved much beyond external living conditions, which, of course, has only made it more stressful for everyone involved - we're still feeling victimised, the grass is still greener on the other side, we're still, as a result, getting angry with the wrong people for the wrong reasons, at the wrong time. Where is that self control that the great epics have professed? Whatever happened to counting 10 before reacting to something?
I've seen a number of people who are quite composed and all, and claim to be extremely calm - but without fail, I've also seen every one of these people lose it unreasonably at some point. Our impulse to get angry, more often than not, translates into a physiological reaction of getting angry - this seems to be our basic evolutionary flaw.