Why we fear what we do not know

In my opinion, we fear the unknown mainly because we have little to no idea what it is or what it is capable of. The fact that it is new to us causes us to feel helpless because we are unfamiliar with whatever we are dealing with, and feel helpless against it. However, there are several types of things that can be unknown to us, such as animals, places, people and equipment. When dealing with a new species, we don't know weather or not the thing we fear means us no harm, or wants to brutally kill and prey on us. Dealing with new people is similar to this, we don't know what they are like and could be very nice or cruel and cold-blooded. When dealing with a new piece of equipment, we don't know how to properly use it and therefor we are scared we could mess up and injure ourselves or anyone around us.