In a Smithsonian article by Devin Powell, the discovery of vanillin in rock in Northern Italy. The rock contains important information about soils from hundreds of millions of years ago. As the name suggests, vanillin, an organic compound, is molecularly very similar to vanilla, a common spice and flavoring that we use today. The vanillin in the soil is rare, because normally after 250 million years, bacteria would have consumed it, leaving no traces. So why does the vanillin remain?
Interestingly, the scientists utilized the dairy industry to figure this out. Apparently, vanilla is often used to enhance the flavor of milk, but the only way to retain that flavor is to lower the pH, or acidify, the milk. While this sheds a somewhat disturbing light on how much staple food items are altered during production, it also provides an interesting (possible) explanation as to why the vanillin has remained in the rock for over 250 million years. The soil must have been much more acidic than normal, indicating that some kind of acid rain or acidic substance was naturally added to the soil, through precipitation or possibly volcanic eruption.
As we already know, vast decreases in pH in soil can be destructive to vegetation and animals throughout the trophic levels. Though the scientists do not yet know what exactly caused the acidification of the soil and how widespread the damage was, the vanillin provides important clues for what to look for in other areas of the world.