Pain is a very important way for our body to tell us somthing is wrong. When you accidentally touch something very hot, you feel pain and instinctively pull your hand away. But if you didn’t feel the pain, you might get seriously burned before you realised that you were damaging yourself.
So pain is there to alert us that something is wrong. It’s just a shame it’s so…. well, painful!
Well, there are diseases where people can’t feel pain, such as congential insensitivity to pain, or leprocy. People who suffer from these illnesses tend to do silly things, like leave their hands on the stove, or wash them in boiling water. Usually, the hands become infected or damaged, until they have to be cut off. These people are more liable to cutting themselves too, or cause other damage. Once of the most common problems is with eating – they can accidentally bite of their own tongue.
The evolution of pain is an important feature, because it prevents us from doing harm to ourselves. You can imagine its evolution in fact:
Individuals which did not feel pain are more likely to put themselves in dangerous situations – either by not learning from a previous experience or by continuing to do something harmful, and so are less likely to pass on their genes, because they die more often! Individuals who feel a negative reaction when they do something harmful will firstly learn not to repeat the action (eg. putting your hand in a fire), and will quickly stop doing anything that is doing them harm. In general, then, the genes for feeling pain as a result of harm coming to the body will become more frequent than genes for not feeling pain.
In fact, some people are physically incapable of feeling pain: