Hashimoto’s thyroiditis, rheumatoid arthritis, type 1 diabetes, Crohn’s disease, lupus — there are more than 100 recognised autoimmune conditions, and their prevalence has roughly doubled or tripled in industrialised countries over the past 50 years. These are modern diseases. Pre-war medical records don’t show anything close to current rates. Something has changed — and evolutionary medicine has a compelling explanation for what.
The immune system learns from its enemies
The immune system is not pre-programmed at birth — it learns. From the moment of first breath, it begins distinguishing self from non-self, friend from foe. This learning process co-evolved over hundreds of millions of years alongside bacteria, parasitic worms (helminths), soil microorganisms, and diverse environmental antigens. These weren’t just tolerated — they were the teachers.
Immunologist Graham Rook’s “old friends hypothesis” refines the earlier hygiene hypothesis: the problem is not that we are too clean in general, but that we have lost contact with the specific microbial companions with which we co-evolved — soil bacteria, helminths, symbiotic gut organisms. These “old friends” actively calibrated the immune response, training it to distinguish genuine threats from harmless self-tissue.
When the teachers disappear
Without the calibrating presence of these microbial companions, the immune system doesn’t become lazy — it becomes confused. Deprived of its usual targets, it is more likely to misidentify self-tissue as a threat. Autoimmunity, in this framing, is not a malfunction. It is the result of a learning system that has been deprived of the curriculum it was designed for.
The epidemiological evidence is striking: autoimmune disease rates are strongly inversely correlated with helminth infection rates worldwide. In regions where parasitic infections remain common, autoimmune conditions are rare. As parasites are eliminated and microbiome diversity falls, autoimmune rates rise. This pattern has been replicated across dozens of populations.
What this means at OQ
OQ does not treat autoimmune disease medically — specialist care is essential. But many patients with autoimmune conditions also have musculoskeletal symptoms, autonomic dysregulation, and chronic fatigue that sit within the scope of osteopathic care. Understanding the immune-nervous system relationship, and the inflammatory cascade that connects autoimmune activity to pain, fatigue, and structural symptoms, informs how we approach the whole person.
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