Nothing in Biology makes sense except in the light of Evolution is what geneticist Theodosius Dobzhansky once said, for it to be repeated and remembered whenever anyone had to meditate about what happens around living beings.
Pain is a biological process and we must seek its purpose and meaning in the light of Evolution.
Pain arises evolutionarily from the biological need to avoid necrosis.
Nothing makes sense in pain if not in the light (or darkness) of necrosis (consummated, imminent or just imagined, feared)
Surprisingly, in publications on pain we can hardly ever find a reference to necrosis, not even in the definition given by the IASP (International Association for the Study of Pain):
“An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage“
“…actual or potential tissue damage…”. The type of damage is not specified. In my opinion, they should clarify it as “necrotic damage”.
Cellular death is a part of life, it’s a physiological event which must be regulated, controlled, watched over. Cells must die according to the rules, by processes managed by the body. Necrosis is the death outside this biological law. A necrotic cell is a pathogen, a dead sack full of lethal chemistry, unleashed DNA. Necrosis should be detected as soon as it occurs. The potentially necrotizing agents and states should be identified and avoided.
Necrosis doesn’t produce pain, but necrotic chain death. The molecular signals that it generates, its identity signals, activate the neuronal sensors of necrotic damage and the electrical signals that bring the information of the incident to all the implicated systems emerge in order to defend the tissue integrity from necrotic danger. Pain is the final action of the alarm process: it’s the way the body communicates to the individual that there is some kind of trouble that must be taken care of.
If there is no consummated or imminent necrosis, pain should not be activated. If there is no necrotic danger, activating pain perception doesn’t make sense, a perception that emerged throughout the Evolution to alert the individual about the risk of violent cell death.
The fact that it doesn’t make sense doesn’t mean it doesn’t happen. The actions of living beings have no guaranteed rationality. In fact, the perception of pain, as other somatic perceptions of alert (hunger, thirst, cold, heat), is often activated without any circumstance of physical danger.
The body of the Homo sapiens (ma non troppo) has evolved with culture, a biological component of first order, and it’s no longer possible to understand its behavior, decisions, if not in the light of culture, as sapiens Culture is Biology, it’s Evolution.
We may have managed to minimize necrosis with culture, but the price is to maintain the pain function irrationally switched on.