Abstract
This paper argues for the sociological relevance of contemporary research from ‘relational’ or ‘systems’ biology on the microbiome-gut-brain (MGB) axis. I review research on the MGB from microbial neuroendocrinology, nutritional psychiatry and other fields with a specific focus on nutrition as a critical element of the social environment influencing gene-environment interactions and a range of social behaviors. I discuss two plausible causal pathways from nutritional factors such as dietary inflammatory potential and hypocholesterolemia to social bonding, violence, and political extremism, and conclude with a discussion of the theoretical, methodological, and epistemological implications of these pathways, and of MGB research and relational biology generally, for social science.