ABSTRACT
Humans share precursors of tendencies towards the recreational use of psychoactive substances and musicality with other animals. However, in humans, those tendencies have since evolved beyond previous parameters. We propose that the expansion of evening activities tied to habitual fire use throughout human evolution might explain their further evolution and integration. The expansion into the nocturnal niche posed recurrent ancestral adaptive challenges/opportunities: lack of luminosity, dangerousness, peak tiredness and concealment of identity. These night-time features might have been selected for evening-oriented individuals to be prone to acoustic communication, more alert and imaginative, gregarious, risk-taking and novelty-seeking, prone to anxiety modulation, hedonistic and promiscuous and disinhibited. As a chain reaction, those four night-time features enhanced and integrated the psychological precursors of psychoactive substance-seeking and musicality guided by sexual selection and assortative mating. Beyond the co-occurrence of promiscuity, substance use and music-making, individuals higher in each of those tendencies are more evening-oriented and share facets of the nocturnal profile. There is also a similar genetic and neurological dopaminergic basis for hypersexuality, psychoactive substance-seeking and musicality. Couples tend to resemble each other in promiscuity, dopaminergic addictions, vocational interests and chronotype which can generate trait covariation integrating these tendencies. Thus, promiscuity, psychoactive substance-seeking and musicality might have coevolved because of the night.
