A possible reason why natural selection chose consciousness

Analog computations may save energy

In this brief outline I assume that feelings like thirst and hunger play a causal role in behavior.  I suggest that one reason why natural selection designed drives this way is because it allows the brain to rely on analog methods when weighing one drive against another.   I speculate that this would provide a fitness advantage if consciousness operates apart from the brain's energy budget.

An example of the mechanism:   a thirsty gazelle, hiding downwind from a spring, smells a lion. The strength of its thirst versus its fear will determine if it risks approaching the water.  The more dehydrated it becomes, the more likely the thirst drive will override the fear.

I skip over the question of whether the brain works this way.  That's not the topic of this article.  The topic is, "If the brain works this way, what could  the fitness advantage be?"

Most readers probably assume that the brain makes decisions of this sort through computations that cost the body energy.   But what if consciousness is to the brain as sunlight is to green plants — something in the environment that the body makes use of?  In that case the decision-making process proposed here might cost the body less energy than one that consists entirely of neural computation. 

Objection

If this is true only the comparison function would be offloaded from neural computation to consciousness. The brain would still have to calculate the intensities of the feelings. Those calculations would constitute the bulk of the energy budget so very little energy would be saved.

Reply

This is an excellent objection. But some drives might require very little computation especially in the forms in which they first evolved. For example, in simple animals, thirst might be simply a representation of blood osmolality and fear might be a representation of how many molecules of a chemical produced by a predator’s body are detected by olfactory receptors.