“…This is reasonable to assume, since the opioid system has strong impact on social emotions and behaviour (Machin & Dunbar, 2011;Panksepp, Herman, Vilberg, Bishop, & DeEskinazi, 1980;Vanderschuren, Niesink, & Van Ree, 1997), infant attachment behaviour (Kalin, Shelton, & Lynn, 1995;Moles, Kieffer, & D'Amato, 2004), and relationship with kin (D'amato & Pavone, 1993). These findings are well in line with the study relating self-report measures of liking and cooperative motives and quality relationship with others as an aspect of slow lifestyle (Krupić et al, 2017). In addition, Elvemo, Landrø, Borchgrevink, & Haberg (2015) recently found that the liking (measured by Reward responsiveness) is reduced in chronic pain patients, which they interpret as a manifestation of a low level of opioids.…”