Where do autoimmune diseases come from?
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Our genes evolved to fight ancient threats, but in the modern world, some of those changes may be turning against us.
ILLUSTRATION: JOHN PROVENCHER/NYTIMES
David Quammen
- Autoimmune diseases such as MS, lupus and Crohn’s disease affect millions. They happen when the immune system attacks the body’s own tissues.
- Researchers say some risk genes came from the Bronze Age and the Black Death. These genes once helped fight infections, but now may raise autoimmune risk.
- The article argues that modern hygiene and medicine have changed the threat. Genes shaped for old infections may now make the immune system overreact.
AI generated
NEW YORK – Evolution does not have purposes, only results. Darwinian natural selection does not shape creatures to be “better” or “higher” in some objective, transcendent sense – it shapes creatures to succeed in the here and now. And what works in one environment or period of time may prove harmful in another. Some scientists say this fact of evolution might help explain the origins of human autoimmune diseases.
They are a bit mysterious, autoimmune diseases, but far from rare. They include multiple sclerosis (MS), rheumatoid arthritis, Type 1 diabetes, lupus, Crohn’s disease, psoriasis and possibly more than 100 others. Some of them cause misery, some discomfort and inconvenience, and some can be fatal. What these conditions share is that, for reasons still unclear, a person’s immune cells begin attacking the body’s own tissues and organs, instead of just defending against invaders like viruses and bacteria.