Pain as warning of potential injury

Although there have been some recent advances in our understanding of how acute pain develops into chronic pain, the process, and more importantly, the reason why this occurs largely remains a mystery. I would like to posit that some of the mystery may clear if we look at pain from a slightly different perspective than usual.

Pain is most commonly considered to be a sign of injury. That is, the primary purpose of pain is to signal injury. The stronger the pain, the worse the injury. But the fact is that pain can arise before any injury has taken place in order to signal that injury is imminent unless action is taken to prevent it. Touching a hot bulb, for example, will elicit pain in advance of any tissue damage. This setup has obvious adaptive advantages. After all, better to prevent an injury altogether than to have to heal after injury has occurred.
But what if all pain amounted to a signal that the brain was predicting injury unless action was taken to prevent it? In other words, what if pain was first and foremost a warning of injury? Put yet another way, pain may be part of a homeodynamic system that is designed to maintain the integrity of the body in the face of threats to this integrity. Many systems can operate without behavioral intervention but some require the organism to perform certain activities. Maintenance of blood sugar and body temperature of 2 examples of the former, whereas hunger and thirst are examples of the latter. It may be that pain may also be an example of the latter.

When thinking of pain as a signal of injury, it becomes quite puzzling why pain might persist even after the instigating injury has healed. We might wonder what kind of crappy system evolution has evolved that would lead to persisting pain long after the injury has gone and the pain has served any useful purpose. But if we look at pain as a motivator to perform a behavior aimed at maintaining or restoring bodily integrity then the chronification of pain seems a bit less mysterious. Here's why...

When an injury occurs, the purpose of pain is not merely to signal injury. What good would it do? What are we supposed to do with this information beside suffer the aversiveness of the experience? Instead, pain is a signal that the brain has reason to believe that some part of the body is at risk and that some form of behavioral response is necessary. With this signal