Social support reduces stress hormone levels in wild chimpanzees across stressful events and everyday affiliations.

Roman M Wittig,Tobias Deschner,Catherine Crockford,Klaus Zuberbühler,Anja Weltring,Kevin E Langergraber

doi:10.1038/ncomms13361

Abstract

Stress is a major cause of poor health and mortality in humans and other social mammals. Close social bonds buffer stress, however much of the underlying physiological mechanism remains unknown. Here, we test two key hypotheses: bond partner effects occur only during stress (social buffering) or generally throughout daily life (main effects). We assess urinary glucocorticoids (uGC) in wild chimpanzees, with or without their bond partners, after a natural stressor, resting or everyday affiliation. Chimpanzees in the presence of, or interacting with, bond partners rather than others have lowered uGC levels across all three contexts. These results support the main effects hypothesis and indicate that hypothalamic-pituitary-adrenocortical (HPA) axis regulation is mediated by daily engagement with bond partners both within and out of stressful contexts. Regular social support with bond partners could lead to better health through daily ‘micro-management' of the HPA axis, a finding with potential medical implications for humans.

Highlights

Stress is a major cause of poor health and mortality in humans and other social mammals
A key mechanism through which these benefits could operate is through social buffering, in which social support provided by bond partners cushions the aversive effects of stressful events through mediation of the hypothalamic-pituitary-adrenocortical (HPA) axis[6,7,8,9]
We first tested if relative urinary glucocorticoid (uGC) levels were influenced by Event

Summary

Introduction

Stress is a major cause of poor health and mortality in humans and other social mammals. Chimpanzees in the presence of, or interacting with, bond partners rather than others have lowered uGC levels across all three contexts These results support the main effects hypothesis and indicate that hypothalamic-pituitaryadrenocortical (HPA) axis regulation is mediated by daily engagement with bond partners both within and out of stressful contexts. While the main effects hypothesis predicts HPA regulatory effects of social partners in both stressful and non-stressful situations, the social buffering hypothesis excludes HPA axis regulation outside of stressful events To test between these two hypotheses and to investigate their predicted impact on HPA axis activity, we monitored subjects’ urinary glucocorticoid (uGC) levels in reaction to acute stressors, everyday affiliations and resting. Since general social support is usually measured as social integration in the community[6,14] or as the presence of reliable supporters[7,11,12,13], we contrasted subjects’ uGC levels in the three contexts depending on the participation or presence of a bond partner, who by definition provides predictable support

Methods

Results

Conclusion