Human beings are thoroughly social creatures. Indeed, human survival in difficult physical environments seems to have selected for social group living [
95]. Consider that the reproductive success of the human species hinges on offspring surviving to reproductive age. Social connections with a mate, a family, and a tribe foster social affiliative behaviors (e.g., altruism, cooperation) that enhance the likelihood that utterly dependent offspring reach reproductive age, and connections with others at the individual and collective levels improve our chances of survival in difficult or hostile environments. These behaviors co-evolved with supporting genetic, neural, and hormonal mechanisms to ensure that humans survived, reproduced, and cared for offspring sufficiently long that they, too, could reproduce [
96–
98]. Human sociality is prominent even in contemporary individualistic societies. Almost 80% of our waking hours are spent with others, and on average, time spent with friends, relatives, spouse, children, and coworkers is rated more inherently rewarding than time spent alone [
99,
100]. Humans are such meaning-making creatures that we perceive social relationships where no objectifiable relationship exists (e.g., between author and reader, between an individual and God) or where no reciprocity is possible (e.g., in parasocial relationships with television characters). Conversely, we perceive social isolation when social opportunities and relationships do exist but we lack the capacity to harness the power of social connectedness in everyday life. Chronic perceived isolation (i.e., loneliness) is characterized by impairments in attention, cognition, affect, and behavior that take a toll on morbidity and mortality through their impact on genetic, neural, and hormonal mechanisms that evolved as part and parcel of what it means to be human. Future interventions to alleviate the health burden of loneliness will do well to take into account our evolutionary design as a social species.
