D Depression (Paul Gilbert) Shane Kavanaugh Kavanaugh Counseling & Consulting, LLC Ames, IA, USA Synonyms Clinical depression; Major depression Definition “A common mental disorder characterized by per- sistent sadness and loss of interest in activities that you normally enjoy, accompanied by an inability to carry out daily activities, for at least two weeks” (World Health Organization 2019). Introduction Professor and clinical psychologist Paul Gilbert utilizes an evolutionary approach toward the study of depression through social rank theory (SRT). This model views depression in terms of adaptive and maladaptive functions. In the context of social conflict, depression functions to tone down a subordinate’ s positive affect, accept defeat/loss (i.e., not meeting one’ s goals), and submit to the dominant and to signal to the dom- inant that the subordinate is not a threat (Price 1972). This process could be seen as adaptive, if it allowed individuals to disengage from nega- tive environments and seek new sources of support (Gilbert 1992; Gilbert and Bailey 2014). Instead, depression blocks these adaptive responses, leaving the stress system in a pro- longed state of arousal and the depressed person feeling demobilized (Gilbert 2000b). Toning Down of Positive Affect Pathways to the toning down of positive affect are explained through the arrested defenses model (Gilbert 1992, 2001). This model states that the body’ s defense system (e.g., fight or flight) in response to stress or perceived threats can become blocked. For example, one may feel a heightened urge to escape but feel trapped or feel anger but suppress negative expression of emotions. This pattern of arousal and blocking of defenses can become chronic, which can lead to the toning down of positive affect. Indeed, depression has been associated with feelings of entrapment © Springer Nature Switzerland AG 2020 T. K. Shackelford, V. A. Weekes-Shackelford (eds.), Encyclopedia of Evolutionary Psychological Science, https://doi.org/10.1007/978-3-319-16999-6_3742-1