Photograph by Dennis Wong
The human nose can detect and distinguish between a trillion different odours, a billion times more than traditionally believed.
In a study published in the journal Science, researchers studying the human sense of smell prepared scent mixtures containing 10,20, or 30 components selected from 128 different odourous molecules. Using a sample set where two of the three scents created were the same, the scientists tasked 26 participants with identifying the scent that smelled differently.
The team of researchers found that the participants that the participants struggled to differentiate between the scents contained components that overlapped by more than about 51%. They then calculated the number of possible mixtures that overlap by less than this percentage to determine how many odours the human nose could potentially smell – one trillion.
The nose is traditionally believed to offer inferior sensory resolution than the eyes, but in reality the one trillion different odours we can smell far outstrips the estimated 7.5 million colour variations we can see, as well as the estimated 340,000 tones of sound we can hear.
