FUSTY FEET

The same bacteria used to ripen strongsmelling cheeses are also found on stinky feet.

Take a sniff - what do you smell? Perhaps Tit's some delicious dinner cooking, freshly cut grass or fragrant flowers. You might also catch a whiff of your pet pooch's pongy poo, your dad's terrible trumps, or even your sibling's stinky feet. Ewwwwww! Stinky smells can strike at any time and, thanks to evolution (the process by which living things develop), your nose knows when it smells something bad. 

There's no shortage of nasty niffs out there.Animals use their stench for lots of different reasons. Skunks squirt an unpleasant liquid when they feel threatened, bears rub their scent on trees to mark their territory, and male musk oxen give off a strong pong to attract females. Humans are no better, with our armpits, cheesy feet and bad bums, but why do certain odours smell so horrid anyway? Let's get to the bottom of this stinky science and find out why it's important for survival?

What is smell?

The parts of your body responsible for your sense of smell are called the olfactory system. It evolved around 700 million years ago in fishy creatures called lancelets. These creatures are the most distantly related animals that share similar olfactory (smell) genes to humans. Genes are coded sequences of DNA, a chemical that carries all the information about a species. They contain the instructions for how an individual creature develops and grows. Lancelets had about 40 genes relating to smell (humans have about 390) and may have been able to turn their whole body into a nose to pick up scents in the water surrounding them. This eventually evolved into the system you have today, but how does it work?