If you think of the nature of our evolution and social habits of humans and other species you will know that to carry a weapon openly in public possibly suggests an assertive dominance or even aggression over the other specimen in the area.
That is how fear has evolved. It is natural to have those that fear. And I have every right to fear because I don't know every madman, idiot and such that could be out there. Despite whether the general idea is that "he won't do anything to harm me"
It is ironic that you quote evolution and social habits as a argument against carrying guns. You do realize that survival of the fittest and outclassing one's competitors are some of the main factors that dictate survival according to evolution, right? Every one of those arguments is pro-gun.
Correlation does not imply causation, however, and that is not why carrying weapons is or should be allowed. It is done for a much deeper reason seated in personal liberty.
I noticed you ended your argument that you have "every right to fear" - please show me where evolution cared once for anything's right to fear.