eli5: Allergies. Why did we as a species develop allergic reactions to certain foods, chemicals ext.?

Question

I just don’t get why our bodies would reject nourishment or have a bad “reaction” to something as simple as grass.

In: 2

Answer 1

Im no expert, but I liken allergies to phobias, mundane things that make you scared AF, the immune system sometimes overreacts to certain things in much the same way. I don’t think it was developed on purpose. (again I’m not an expert just leaving my 2 cents)