Within milliseconds, our primitive brain analyzes the situation and creates a bodily response – fight or flight.
And a million years ago, when this response developed – we could outrun any other animal on the earth. Because we had little body hair, and sweat glands in our skin. They might overtake us, if caught by surprise, and make a meal of us, the same as any other animal – but after that, we left them far behind.
And if there was more of us, as was often the case – we could take our weapons, and go after the attacker – who would beat a hasty retreat – before we made a meal of it.