Almost anyone will defend themselves if they are in what is perceived as a life or death situation.
Insults can easily provoke rage.
Protecting family members from threat or attack.
Protecting your own territory or home, which are basic needs of survival.
Violence is often used to obtain or protect a mate.
Order in Society
Rage frequently breaks out in response to perceived social injustice.
Violence can be used to obtain and protect resources (money, valuables, property).
In group / out group mentality. Throughout history humans have been divided by tribe, country, religion, etc. attacking and defending against one another.
Being restrained, imprisoned, cornered, or impeded pursuing ones desires. The accompanying emotion is frustration.
This list comes from the book Why We Snap by R. Douglas Fields. Concise list of rational. I might add a couple things to the list of people lashing out (possibly not rage, but having an effect on ones thresh hold of lashing out)
Not to mention hormonal (both naturally or drug induced). We could also add mentally unstable, chemically imbalanced, head injuries, hurt or perceived vulnerability, under the influence of drugs or alcohol.
Anyway, I haven't read the book, but someone (Tim W.) forwarded me the Why We Snap pdf and I thought it was worth posting.
You can get Dr. Fields book here: