It stands to reason that such an improvement in the environment has generally resulted in an objectively diminished range, amplitude, of individually experienced affective states (AAS). The situation may be similar to the underloading of the immune system in the modern environment compared to the environment of evolutionary adaptedness, EEA (Bowlby, 1969), as the potential cause of chronic inflammatory, autoimmune and allergic diseases (e.g., Rook, 2009). Analogous to the overactivity of the immune system in the absence of the agents to fight against in genetically highly predisposed individuals, some of them may seek ways to make up for lacking the wide fluctuations of stimulants (danger in particular) that the nervous system has evolved to experience. These individuals, which could be well adjusted in the EEA, are not optimally adjusted in the current environment. Thus, their status of the nervous system is underarousal, resulting, e.g., in high novelty and sensation seeking (including that from substance use), risky and antisocial behavior, etc. This becomes emphasized particularly at transition to the reproductive period (which defines fitness) and relative independence, i.e., at adolescence. Cognition
