Evolutionary mechanisms for loneliness

Abstract

Robert Weiss (1973) conceptualised loneliness as perceived social isolation, which he described as a gnawing, chronic disease without redeeming features. On the scale of everyday life, it is understandable how something as personally aversive as loneliness could be regarded as a blight on human existence. However, evolutionary time and evolutionary forces operate at such a different scale of organisation than we experience in everyday life that personal experience is not sufficient to understand the role of loneliness in human existence. Research over the past decade suggests a very different view of loneliness than suggested by personal experience, one in which loneliness serves a variety of adaptive functions in specific habitats. We review evidence on the heritability of loneliness and outline an evolutionary theory of loneliness, with an emphasis on its potential adaptive value in an evolutionary timescale.

Figure 1

The effects of loneliness on human cognition. From Cacioppo, J. T., & Hawkley, L. C. (2009). Perceived social isolation. Trends in Cognitive Sciences,13, 447–454.

Figure 2

Top panel. A cluster of voxels centered in the ventral striatum, but extending to the amygdala and portions of the anterior thalamus, showed an inverse relationship between loneliness and activation in the Pleasant Social – Pleasant Nonsocial contrast. Bottom Panel. Clusters of voxels in the left and right visual cortices exhibited a positive relationship between loneliness and activation in the Unpleasant Social – Unpleasant Nonsocial contrast; whereas clusters of voxels in the left and right TPJ exhibited a negative relationship between loneliness and activation in the Unpleasant Social – Unpleasant Nonsocial contrast. Cacioppo, J. T., Norris, C. J., Decety, J., Monteleone, G., & Nusbaum, H. (2009). In the eye of the beholder: Individual differences in perceived social isolation predict regional brain activation to social stimuli. Journal of Cognitive Neuroscience, 21, 83–92.