I have always wondered why some people faint by the sight of their own blood. I am one of them that feels a sudden urge to cuddle the floor by seeing my blood. Why?! Now I have come across a possible explanation to this. It`s called blood phobia.
All forms of phobia has its roots in situations that once upon a time was threatening to humans, such as open spaces (dangerous because we could be seen and attacked), snakes, spiders (which are no longer dangerous in many countries today), etc. Being afraid of these situations and the animals, made you avoid and then survive in the harsh environment.
Some psychologists believe that the fear of blood is a fundamental phobia. Blood was at that time(and still is)a sign of danger. It was “smart” to respond with a lowered blood pressure, that made the blood supply to the open wound less, which again caused the bleeding to be less. And as we all know, the reduction in blood pressure can cause dizziness and fainting.
And the one who reacted with fear had a bigger chance of survival. They were more careful of not putting themselves in situations that might be dangerous and make them bleed; maybe bleed so much it lead to death.
It`s a matter of survival.
Why some has this survival instinct so strong in them and others don`t react at all; no one knows for sure.