Chalk this up as another reminder that we need to rethink our germaphobic concepts of "clean" and "dirty." I had a geology teacher in high school who wouldn't let us say the word "dirt" in class—he thought the word had negative connotations that didn't do justice to the life-giving power of soil. It pains me to say it now, but Mr. Lundgren: you were right. Soil isn't dirty, it's good for you.

Think about it for a second. Animals have been eating around dirt for millions of years, but we've only been using pesticides for a couple of generations. It shouldn't surprise anyone that a chemical-filled, dirt-free diet is going to have some negative, unintended consequences for us—like causing learning disabilities in children. And that's not even beginning to mention the effects on the rest of the planet.

Looking for ideas of how to get some of that smart, dirty bacteria into your system? Start an organic garden. Here are 5 tips to get you started. And here are 2 easy compost recipes.

Image Credit: Steven DePolo