Social proximity and interaction attenuate cardiovascular arousal, facilitate the development of nonanxious temperament, inhibit the release of stress hormones, reduce threat-related neural activation, and generally promote health and longevity. Conversely, social subordination, rejection and isolation are powerful sources of stress and compromised health. Drawing on the biological principle of economy of action, perception/action links, and the brain’s propensity to act as a Bayesian predictor, Social Baseline Theory (SBT) proposes that the primary ecology to which human beings are adapted is one that is rich with other humans. Moreover, SBT suggests that the presence of other people helps individuals to conserve important and often metabolically costly somatic and neural resources through the social regulation of emotion.