Pain is often portrayed as the guardian of life. Unpleasant sensations are undisputedly in the service of the self-preservation of living beings. However, it is questionable whether the first sensations in evolution must have been those of pain. The emergence of a new property cannot be derived from the function that the property has once it is there. In evolution, new properties are not produced by needs (this would be teleological thinking), but by mutations and selection. Accordingly, rather than pain, the first sensation of an early creature may just as well have been a neutral (or pleasant) sensation. Furthermore, it is conceivable that the self-preservation of early organisms and evolutionarily old and successful species (such as bacteria or jellyfish) is achieved by biochemical processes without the involvement of consciousness. The individuals of evolutionarily very old extant species may still have a kind of luxury primitive consciousness (restricted to neutral or pleasant sensations) hovering above organismal needs. This has ramifications as regards argumentative standards of antinatalist moral theory, for example.
Karim Akerma (Mon,) studied this question.