Also once we feel threaten and afraid we immediately fall into protection mode where our innate behavior is exhibited. You can think of our 4-5-year-old self as a sample. Things like selfishness, anger and doing what we can to get the upper hand, starts to be seen in us.
If you think about it, it takes a lot of years of teaching by society and parents to keeps us from being selfish, angry and whatever basic instincts we have. But even with that, we all fall into those modes when threaten and we are afraid.