why pollen allergies?

Allergies are a big problem for a lot of people. If you're someone with pollen allergies, maybe you've wondered how people in the distant past dealt with them. After all, a thousand years ago people mostly worked outside all day, in areas where plants grow well. They had no air purifiers, no allergy medication, and no extra food for people who couldn't work when it was time to plant crops. The answer is, pollen allergies just weren't very common back then. There was a massive increase in their p...