According to its evolutionary conceptualization, loneliness is considered an internal signal (i.e., social pain) that alerts its experiencers to a threat to social relationships and promotes relationship restoration. Although this conceptualization seems plausible, it needs to be reconciled with seemingly inconsistent findings. First, loneliness is often defined as perceived social isolation, which does not necessarily correspond with objective isolation. The discrepancy between objective and subjective social isolation implies that loneliness is not an accurate signal of social isolation. Second, social pain is associated with not only prosocial behaviors but also aggressive behaviors, which are detrimental to social relationships. Third, chronic loneliness is associated with a wide range of health problems, which seems incongruent with the notion of loneliness as an adaptation. This review addresses each of these three issues and argues that the evolutionary conceptualization of loneliness can integrate these apparent contractions.
