Evidently, scientists have discovered that there are "feel good" microbes that live in the soil. When we play in the dirt (or eat them somehow -- I didn't figure that out), those microbes travel around in our bodies giving off all these little happy vibes that make us feel better. Mice injected with the microbes swim around longer in a water-filled beaker before giving up than mice that didn't have the microbes.
I hope they rescued the mice. Seriously!
This is a really interesting article and doesn't take too long to read. Check it out -- you might need to copy and paste the link. (and thank-you, Angie, for sending it to me -- big hugs to you)