Reward- and stress-related neural processes are frequently considered in isolation from each other. However, a conceptualization informed by an evolutionary perspective helps highlight their intricate interrelationship. Approach and avoidance are broad classes of ancestral responses that guide an organism to emit behaviors in search of life-sustaining resources and to avoid harms, thus supporting survival (Alcaro and Panksepp, 2011; Korte et al., 2005). Accordingly, approach and avoidance systems are highly conserved Their neuroanatomical substrates are phylogenetically old, such as the BG, the amygdaloid complex, the HYP and other conserved structures of the brain. In addition, as nonhuman primates and humans left their ecological niches and became able to adapt to a broader range of environmental conditions, the neocortex evolved an ability for more flexibly shaping approach and withdrawal responses, suggesting that unique features may distinguish these species (Noonan et al., 2012).
