Why have allergies (especially severe ones) not been wiped out by natural selection?
In: Biology
Allergies have become much more common in the last 50 years, but almost only in developed countries. We don’t quite know why that is the case, but the change happened much too quick for it to be purely genetic. This is therefore strong evidence that being allergic mainly isn’t a genetic precondition but has an environmental or lifestyle trigger(s). One theory is that our good hygiene today makes the immune system “bored” and trigger happy.
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