More than 10,000 years ago, around the beginning of organized agriculture, humans were already starting to shift towards a more hygienic life. Agriculture brought social stratification, which created wealthy pockets of society who started creating treatments for a wide array of medical ailments. These treatments quickly became preventative, and the age of sanitation was born. Morrow outlines how early increases of allergies, diseases, and hay fever were all found in upper class, large family populations. While wealthy populations were certainly more likely to report medical problems, the data held true even when controlling for these variables. As more populations gained access to these methods of sanitation, they too fell victim to weaker immunity.

So what are we to do? As Morrow would have it, we should start eating dirt and picking our noses more. This lifestyle change, however, might not quite work for everyone. It is important to remember that every interaction we have with the outside world is helping to train our immune systems. Even if we can’t start eating our boogers every day, we can remember that a little dirt on our jeans isn’t always a bad thing.