Microbes colonise all multicellular life, and the gut microbiome has been shown to influence a range of host physiological and behavioural phenotypes. One of the most intriguing and least understood of these influences lies in the domain of the microbiome's interactions with host social behaviour, with new evidence revealing that the gut microbiome makes important contributions to animal sociality. However, little is known about the biological processes through which the microbiome might influence host social behaviour. Here, we synthesise evidence of the gut microbiome's interactions with various aspects of host sociality, including sociability, social cognition, social stress, and autism. We discuss evidence of microbial associations with the most likely physiological mediators of animal social interaction. These include the structure and function of regions of the ‘social' brain (the amygdala, the prefrontal cortex, and the hippocampus) and the regulation of ‘social’ signalling molecules (glucocorticoids including corticosterone and cortisol, sex hormones including testosterone, oestrogens, and progestogens, neuropeptide hormones such as oxytocin and arginine vasopressin, and monoamine neurotransmitters such as serotonin and dopamine). We also discuss microbiome‐associated host genetic and epigenetic processes relevant to social behaviour. We then review research on microbial interactions with olfaction in insects and mammals, which contribute to social signalling and communication. Following these discussions, we examine evidence of microbial associations with emotion and social behaviour in humans, focussing on psychobiotic studies, microbe–depression correlations, early human development, autism, and issues of statistical power, replication, and causality. We analyse how the putative physiological mediators of the microbiome–sociality connection may be investigated, and discuss issues relating to the interpretation of results. We also suggest that other candidate molecules should be studied, insofar as they exert effects on social behaviour and are known to interact with the microbiome. Finally, we consider different models of the sequence of microbial effects on host physiological development, and how these may contribute to host social behaviour.

中文翻译：

---

微生物组在社会行为神经生物学中的作用

微生物在所有多细胞生命中定殖，肠道微生物群已被证明会影响一系列宿主生理和行为表型。这些影响中最有趣和最不为人所知的影响之一在于微生物组与宿主社会行为的相互作用领域，新证据表明肠道微生物组对动物社会性做出了重要贡献。然而，人们对微生物组可能影响宿主社会行为的生物学过程知之甚少。在这里，我们综合了肠道微生物组与宿主社会性各个方面相互作用的证据，包括社交能力、社会认知、社会压力和自闭症。我们讨论了微生物与动物社会互动最可能的生理介质相关的证据。这些包括“社交”大脑区域（杏仁核、前额叶皮层和海马体）的结构和功能以及“社交”信号分子（糖皮质激素，包括皮质酮和皮质醇，性激素，包括睾酮、雌激素和孕激素、神经肽激素（如催产素和精氨酸加压素）和单胺类神经递质（如血清素和多巴胺）。我们还讨论了与社会行为相关的微生物组相关宿主遗传和表观遗传过程。然后，我们回顾了微生物与昆虫和哺乳动物嗅觉相互作用的研究，这有助于社会信号和交流。在这些讨论之后，我们检查了微生物与人类情绪和社会行为相关的证据，重点是心理生物学研究，微生物与抑郁症的相关性、早期人类发展、自闭症以及统计能力、复制和因果关系问题。我们分析了如何研究微生物组-社会性联系的推定生理介质，并讨论与结果解释相关的问题。我们还建议应该研究其他候选分子，只要它们对社会行为产生影响并且已知与微生物组相互作用。最后，我们考虑了微生物对宿主生理发育影响序列的不同模型，以及这些模型如何影响宿主的社会行为。并讨论与结果解释有关的问题。我们还建议应该研究其他候选分子，只要它们对社会行为产生影响并且已知与微生物组相互作用。最后，我们考虑了微生物对宿主生理发育影响序列的不同模型，以及这些模型如何影响宿主的社会行为。并讨论与结果解释有关的问题。我们还建议应该研究其他候选分子，只要它们对社会行为产生影响并且已知与微生物组相互作用。最后，我们考虑了微生物对宿主生理发育影响序列的不同模型，以及这些模型如何影响宿主的社会行为。