Using the lens of her constructed theory of emotion, Barrett questions whether animals have the three necessary ingredients to experience emotions: interoception, emotion concepts, and social reality. The author focuses on primate species since they’re most closely related to people. Like humans, all animals must manage their body budgets and therefore require an interoceptive network. In macaques, a kind of monkey, the interoceptive network is similar to that in the human brain. Macaques have also been shown to experience affect, as their nervous systems respond differently to positive and negative stimuli. Barrett argues that if macaques feel affect, then other primates would too, given their similarities. However, she’s unsure how other mammals function emotionally. She claims that they must “feel pleasure and pain, as well as alertness and fatigue” (255). Barrett notes that studying animal brains is challenging because some of their brain regions are similar to those in human brains but serve different purposes. The author argues that the most ethical approach is to assume that all animals can experience affect and some degree of emotionality. Humans have an unusually large “affective niche,” or the amount of things that can possibly influence your body budget and emotions.