!Allergy!

[Pie]

Originally posted by warch
Well isnt there the theory that if you are exposed as a babe to various irritants, critters, hay, dust, etc. you develop tolerance. We're just too clean and tidy these days. Maybe we need to camp more as infants, eat dirt, sleep with fur.

It actually has more to do with the level of bacterial and viral agents we are exposed to while our immune systems are developing.

Lymphocytes that are not actively trained to respond to real threats often get re-assigned to inappropriate triggers like pollen, mites, pet fur, etc. This is called the Hygiene Hypothesis:

"According to this "hygiene hypothesis,'' the human immune system evolved two types of biological defenses. When one defensive system lacks practice fighting bacteria and viruses, perhaps from an overly sanitary lifestyle, the other system becomes too powerful and overreacts -- as an allergic reaction -- to harmless substances like pollen."