Why We Have Seasonal Allergies

An interesting new theory holds that people have developed allergies as a sort of superannuated immune response to parasites. After millennia spent in close contact with, and exposure to, parasitic worms, goes the theory, our immune systems have evolved to push back against the telltale proteins they produce:

Why would parasite-fighting systems turn their attention to allergens in the first place? Furnham and colleagues put one theory to the test. “There must be some form of molecular similarity operating between the proteins that cause allergies and the proteins that your immune system is expecting to see in parasites like worms,” he says.

It is an intriguing theory borne out by some clever experimental designs. And it makes a sensible case for the chronic nature of many allergic reactions in the developed world:

Because allergens aren’t really parasites, it may be that once they are targeted, the mechanisms to ratchet down the response never kick in, leading to lasting allergies with unfortunate results. Some allergies can prove fatal, but even relatively harmless versions can be so infuriating that they lead some people to extreme behaviors—like tracking every single sneeze for five years to identify and fix a pollen allergy.

Until we know more and can “turn off” these once-adaptive responses, the best treatment for seasonal allergies remains the same: minimize exposure, and see a sinus doctor if you’re looking for a longer lasting cure.