Department of Biosciences, Faculty of Science and Engineering, Swansea University , Swansea SA2 8PP, UK.
Department of Evolutionary Biology and Environmental Science, University of Zurich , Zurich 8057, Switzerland.
Biol Lett. 2024 Aug;20(8):20240163. doi: 10.1098/rsbl.2024.0163. Epub 2024 Aug 7.
Social bonds increase fitness in a range of mammals. One pathway by which social bonds may increase fitness is by reducing the exposure to physiological stress, i.e. glucocorticoid (GC) hormones, that can be detrimental to health and survival. This is achieved through downregulating hypothalamic-pituitary-adrenal (HPA)-axis activity. Indeed, long-term measures of social (grooming) bonds are often negatively correlated with HPA-axis activity. However, the proximate role of physical touch through allogrooming remains an open question in the sociality-health-fitness debate. Demonstrating the potential anxiolytic benefits of grooming in the wild is hindered by methodological limitations. Here, we match accelerometer-identified grooming in wild female chacma baboons () to non-invasive faecal GC metabolite concentrations (fGCs). Consistent with previous work, we found a negative (but statistically non-significant) overall relationship between individual averaged fGCs and grooming rates. However, when time-matching grooming to fGCs, we found that both more giving and receiving grooming were followed by higher fGCs. This upregulation of HPA-axis activity suggests that maintaining social bonds (and its ultimate fitness benefits) may come at a shorter-term physiological cost. This finding sheds new light on a ubiquitous social behaviour typically considered 'relaxing' and suggests that sociopositive contact can trigger physiological stress.
社会联系在多种哺乳动物中增加适应度。社会联系增加适应度的一种途径是减少生理应激的暴露，即糖皮质激素（GC）激素，这对健康和生存可能有害。这是通过下调下丘脑-垂体-肾上腺（HPA）轴的活动来实现的。事实上，长期的社会（梳理）联系措施通常与 HPA 轴活动呈负相关。然而，异体梳理的身体接触的直接作用在社会性-健康-适应度的争论中仍然是一个悬而未决的问题。在野外展示梳理的潜在抗焦虑益处受到方法学限制。在这里，我们将野生雌性狒狒中的加速计识别的梳理与非侵入性粪便 GC 代谢物浓度（fGCs）相匹配。与之前的工作一致，我们发现个体平均 fGCs 和梳理率之间存在负相关（但统计学上不显著）。然而，当将梳理与 fGCs 时间匹配时，我们发现给予和接受更多的梳理都会导致更高的 fGCs。HPA 轴活性的这种上调表明，维持社会联系（及其最终的适应度益处）可能会带来短期的生理成本。这一发现为一种普遍存在的通常被认为是“放松”的社会行为提供了新的视角，并表明社会积极接触可以引发生理应激。
