‘I read today that humans are more sensitive to the smell of an impending rainstorm than sharks are to the scent of blood. However, the funky odor that we associate with rain a-comin’ isn’t in the rain itself, nor is it the smell of wet asphalt, as I used to believe as a kid. It’s an aroma created by a compound called geosmin.

Geosmin smells kinda musty, a little like a pair of garden gloves after they’ve been digging around in moist topsoil. There’s a reason for this: geosmin’s also responsible for the smell of said soil. The compound is generated by some algae and strains of bacteria that reside in soil. Just add water.

In addition to the smell we’ve come to associate with a downpour, geosmin also plays a significant role in why beets taste the way that they do. In 1964, the smell of rain falling on dry, geosmin-rich soil was coined as petrichor by chemist Isabel Joy Bear and mineralogist Richard Grenfell Thomas.

Not too long ago, it was put forward in a paper that our ability to detect the odor of geosmin was a feat of survival for early humans and our early primate pals. The scent of the compound may have helped our predecessors find water during a drought.…’ (via Boing Boing)