Janeway's hypothesis is a foundational immunology concept: the immune system is trained to recognise microbial patterns on bacteria that the body learns to either tolerate or attack. Your gut microbiome plays a central role in this education. Early-life microbial exposure literally shapes which immune responses develop which is partly why antibiotic use in infancy is associated with significantly higher rates of allergies, asthma, and autoimmune diseases in later life.
