What's that smell?
Until now it was believed that the human nose and its 400 olfactory receptors could detect only 10,000 different aromas. But now US scientists at Rockefeller University New York, have found we can detect 1 trillion odours. The human eye uses three light receptors that work together to see up to 10 million colours, while the ear can hear almost half a million tones.
They experimented on 26 people and tested how good they were at distinguishing between cocktails of 128 different odour molecules, representing a large range of smells from grass to citrus. The 26 people were then asked to identify a scent from three samples - two that were the same and one that was different. The results were then extrapolated to see how many different aromas the average person could discriminate between. And 1 trillion is thought to be an underestimate!