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What is That Smell?

Smell is the least appreciated of our five senses. Yet odours can influence the way we feel, warn us of danger, stimulate our appetite, and unlock our memories.

When we smell, we perceive odours because tiny microscopic particles floating in the air react with special cells in the lining of our noses. Just a few molecules are often enough to trigger a smell.

Many insects use a kind of smell language, using chemicals called pheromones to communicate. Some insects use pheromones as sex attractants! A female moth produces a volatile chemical that is detected by tiny hairs in the male moth’s antenna. Some male moths can follow a sex attractant odour for many miles. A single molecule in the air is enough to start him flying up wind in search of a female!

Bloodhounds can follow the scents produced by sweat and skin. They can keep on the trail because each person has a highly individual smell - as unique as a fingerprint.

Scientists find it difficult to classify primary odours, because different people smelling the same odour, react in different ways. Our reaction to odours is influenced by past experiences, our age, and even things like the time of the day.

In one study, scientists found young women preferred the scents of lavender and almond, while the favourites for young men were musk and orange blossom.

So next time you respond to a smell, remember that it is the shape of a little molecule that triggers the mood and memory.

Smell is often used as a metaphor. This is particularly true of unpleasant smells. We might speak of a despicable act as one that “stinks of treachery.” Or if we have negative intuition about a situation we might express our concerns with, “I don’t like this, there’s something about it that just smells bad.”

There are some smells which seem to be universally perceived as unpleasant to humans. Burning protein, rotting carrion, and excreta are a few that pop to mind. Most of us, whether or not we believe in God, see a warning function connected to those unpleasant smells mentioned earlier. The unpleasant smell of burning protein alerts us to the danger of fire. The stench of rotting carrion and excreta keeps us away from dangerous sources of bacterial infection.

On a higher level there are some behaviours which seem to be generally viewed as reprehensible. Acts of cruelty against innocents, exploitation of the weak and poor, treachery against those who trust you are a few examples that come readily to mind. It seems that humans, regardless of their philosophical views. have some innate understanding that some things are just plain “wrong.”

Our “sense of moral smell” also ought to alert us to danger. The Bible continually warns us about how God reacts to “injustice” and “unrighteousness” - the very things that metaphorically smell bad to us. These are much easier to identify in others than in ourselves. But, for our own good, we need to be watchful of cruelty, exploitation, treachery and other attitudes and actions which God condemns.

It’s worth noting that it is not enough to merely identify what God calls “sin” in our lives. We need to do something about it besides simply avoiding it. By acting directly on our behalf, in the man Jesus, God removes the consequences of sin and offers us His righteousness. So next time you smell something really unpleasant, remember how your sin smells to God and take advantage of God’s offer to “cleanse you from all sin.” (1 John 1:7)

David Humphreys and Ron Hughes
© August 2004