The Science Behind The Smells We Be Smellin’

The chemical ecology of the Willamette Valley is dynamic, and yet it is invisible. We exist within a web of molecular interactions of which we are hardly cognizant. Tiny pieces of living and nonliving things are constantly colliding with our bodies, producing all kinds of effects, some of which we can sense. 

Some of these tiny pieces of matter can produce recognizable signatures within our biological circuits that we call “smells.” These can become markers of place, connecting us back to memories that were formed in environments that are bombarded with particular molecules.

The Willamette Valley has some instantly recognizable smells, due to some molecules that are uniquely abundant in particular locations. 

Here are a just few you should probably know about:

With the slightest touch of moisture, geosmin is immediately apparent on the floor of the Valley. A product of soil-dwelling microbes, this compound is responsible for the smell of wet earth. Areas with disturbed soil, such as tilled fields, have high concentrations of this particular shape.

The border of the Coast Range is often thick with pinene. This compound is brought to us by the millions of coniferous trees that blanket those hills. It is just one of many compounds released by these trees that carry effects for processes as distinct as the formation of weather and the function of our own cells.

On hot days, skatole permeates the air near wastewater treatment plants. This compound is characteristic of human waste, and is objectionable to almost everyone.

Heat also brings various alkanes up from the surfaces of roads and parking lots. These carbon chains are associated with the places we take our cars, and they have oily, fuel-like scents.

Summer’s end leaves tons of rotting fruit to melt into the ground. This decomposing plant tissue throws many kinds of esters into the air, and they hang above the ground near apple trees and blackberry bushes.

These molecules, along with many others, mark these locations in our minds, connecting us to the invisible physical reality of the chemistry that surrounds us.

By Scott Bittner