The short answer is: sort of. When you smell poo, tiny molecules from the faeces actually enter your nose. They are not tiny pieces of poo, but odour molecules that evaporate and are then picked up by your nose. In this video by Universiteit van Nederland, Sissi de Beer, an applied physicist at the University of Twente, explains exactly how this works.
Why does fresh poo smell stronger?
The warmer something is, the more easily molecules evaporate. That is why hot coffee smells stronger than cold coffee. The same applies to poo: while it is still warm, more odour molecules are released and eventually reach your nose.
But a single molecule does not immediately tell your brain: this is poo. Your nose contains around 300 different types of olfactory receptors. Odour molecules activate different combinations of these receptors. Your brain then recognises this pattern as a particular smell, such as coffee, orange or poo.
Can you build an artificial nose?
That is exactly the principle Sissi is trying to mimic in her research. Together with her team, she is developing an electronic nose with different sensors, each of which responds differently to odour molecules. Just like in our own noses, this creates a pattern that can be used to recognise different smells.
The electronic nose can already distinguish between scents including lavender and different whiskies. Sissi and her colleagues are investigating how they can teach the electronic nose to recognise an increasing number of different smells. In the future, such a sensor could have much more serious applications, for example detecting explosives and hazardous substances or helping to locate people trapped under rubble after an earthquake.
See how our sense of smell really works
But how exactly do those odour molecules get into your nose? And how do you build an artificial nose? Sissi explains it all in the Universiteit van Nederland video at the top of this page.
