Milk bioactives maymanipulate microbes tomediate parent-offspring conflict

Among mammals, milk constituents directly influence the ecology of the infant's commensal microbiota.The immunological and nutritional impacts of breast milk and microbiota are increasingly wellunderstood; less clear are the consequences for infant behavior. Here, we propose that interactionsamong bioactives in mother's milk and microbes in the infant gut contribute to infant behavioralphenotype and, in part, have the potential to mediate parent-offspring conflict. We hypothesize thatinfant behavior likely varies as a function of their mother's milk composition interacting with the infant'sneurobiology directly and indirectly through the commensal gut bacteria. In this article, we will exploreour hypothesis of a milk-microbiota-brain-behavior dynamic in the context of the coevolution betweenhuman milk oligosaccharides, bacteria, the gut-brain axis and behavior. Integrating established featuresof these systems allows us to generate novel hypotheses to motivate future research and considerpotential implications of current and emerging clinical treatments.