Surviving in difficult situations does not necessarily require a great brain: hunger is an equally effective spring, because it preserves the memory of past virtuous behavior.

The first, fundamental instinct. | Shutterstock
Never underestimate a stomach that growls: animals - humans included - can make surprisingly accurate decisions when they are driven by hunger. This is suggested by a study by the University of Exeter (England), according to which survival in difficult and threatening situations does not necessarily require great brain work: learning to listen to one's hunger, in certain situations, pays just as effectively.
A group of ethologists led by Andrew Higginson has used computer models to demonstrate that under conditions of food scarcity and abundance of predators, animals (individuals) who base their decisions only on energy reserves left in the body survive as much, or as little less, those who resort to more "reasoned" assessments of what to do.
THE STOMACH REMEMBER. Hunger acts as a sort of memory of food available in the past, and how we got it; reveals if we have succeeded and how we should behave to ensure survival again. All this information is processed automatically, without allocating cognitive resources (very expensive from an energy point of view).
A MORE IMMEDIATE SYSTEM. This form of belly memory would have allowed many animals to survive without developing large amounts of brain tissue and partly explain why when we are hungry it also affects the mood: the "belly" is telling us that there are not many food reserves available.
TRUST THE INSTITUTION. Research paves the way for other physiological states, like some emotions, to retain a sort of memory of the past. Fear, for example, generates a state of physiological alert from which it is difficult to recover: because the danger could recur, emotions keep the body tense in a state of attack or flight, to be able to act without it being necessary to think about it.