Probably, none of us has ever experienced a serious and long-term shortage of food. But in principle evolution has endowed us and other vertebrates with mechanisms that alter our physiology, brain mechanisms, mental states, and behavior when environmental cues signal an upcoming scarcity of food. But what are these mechanisms? Biopsychologists now published a comprehensive theory on the mechanisms of foraging in the top tier theory-journal “Behavioral and Brain Sciences”.
The theory departs from the observation that both mammals and birds are extremely sensitive to a drop in the probability to find food and reliably react with an invigoration of food-related responses. During such a time these animals consume and/or hoard more food, get fatter, and build up a reserve against future starvation. This even happens when people are anxious to lose their job. In this paper it is argued that an anticipated long-term drop of resources has motivational effects called incentive hope that facilitates foraging effort by an altered release of dopamine - a neurotransmitter strongly involved in inducing incentive motivation. This increases the subjective value of food, promotes higher efforts to collect and consume it, and results in higher bodily or hoarded long-term energy storages. The paper shows that this hypothesis is computationally tenable, leading foragers in an unpredictable environment to search for and to consume more food items. Altogether, this theory bridges the troubled waters between ecology, psychology, and neurobiology. Twenty-three research groups have responded to the call to discuss this novel theory. Their comments are subsequently discussed and integrated into the body of their theory.

Anselme, P. and Güntürkün, O.. How foraging works: Uncertainty magnifies food-seeking motivation, Behav. Brain Sci., Behav. Brain Sci., 2019, 42: e35, 1–59.