1. Language Lab Summer Session (2025)

Welcome to our 1st session in olfactory expression.

Welcome to the first session of the Language Labs Summer Sessions!

Today I want to focus on the commonly used word “stinky”.

“Something really smells stinky in here.”

“Phew, that stinks!”

“Oh gross! That’s really stinky.”

A strange place to begin, you might ask? Well maybe, but I think it’s the perfect place to start and here’s why…

Stinky odors are some of the oldest smells we know as humans. Earth’s volcanoes and hot springs have been emitting stinky odors, made largely of sulfur compounds, throughout time. In fact, the most primeval smell - hydrogen sulfide (H₂S) - was around long before the earliest organisms even existed. You recognize it as the “rotten egg” smell. Yeah, that one. There are other common sulfur compounds, like methyl mercaptan (CH₃SH) which is found in bad breath and in some cheeses.

We humans have a biological sensitivity to these compounds. Our noses are exceptionally tuned to sulfur compounds like mercaptans due to evolutionary adaptations; it helps us survive by avoiding spoiled food or harmful gases.

Fun Fact:
Did you know that humans can detect the sulfur compound ethyl mercaptan (C₂H₅SH) at concentrations as low as 0.0003 parts per billion (ppb) in the air, making it one of the most odor-sensitive substances for our nose? You’ll find ethyl mercaptan commonly added to natural gas, which is actually odorless, to give it that distinctive smell for leak detection.

But there’s another reason to start with this word…

Because we’re naturally wired for the negative. Our brain has something called negativity bias, which means we have the tendency to focus more on negative experiences than positive ones. We’re attuned to the bad - the stinky - largely for survival. We notice it more, and we comment on it a lot!

So, let’s explore the wonderful world of stink this week. Here’s what I want you to do…