 Others refer to these stable immune interactions with microbiota to deny that organisms are individuals (S. Gilbert, Sapp, and Tauber 2012). Appreciating the ubiquity of symbiosis, the immune system from this point of view becomes a key mediator of the holobiont by tolerating and coordinating microbial-host relationships. On this basis, these critics highlight that most of these interactions fall on a dynamic spectrum of rejection and acceptance making it impossible, in principle, to determine the boundaries of individuality. Symbiotic interactions do not conform to a simple acceptance-rejection model. Rather, to attune its responses to microbial signals the immune system launches a broad spectrum of T-cell reactions in combination with a variety of innate immune and tissue cell-derived signals (cytokines, hormones, neurotransmitters) in combination with complex regulatory controls (Eberl 2016). As suggested by Cohen, immunity is the product of an active computational state that constantly assesses the state of the organism’s internal state and the surroundings in which it lives (Cohen 2007a, 2007b). In the context of such fluid activity, transitioning from one unique activation state to another does not allow definitive delineation of organismal borders. Instead, the immune system acts as gatekeeper that controls the apparent boundary between the organism and its environment (Tauber 2008: 231; Tauber 2017; S. Gilbert, Sapp, and Tauber 2012). From this perspective, the view of immunity as protecting insularity shifts to recognizing its role in establishing and maintaining communal relationships that blur the distinction of an atomistic insular individuality (Skillings 2016).