The human sense of smell is extraordinary. Our eyes can distinguish several million colours, our ears can distinguish half a million tones, but our noses can distinguish well over a trillion different odours. Humans can detect virtually all volatile chemicals ever tested. We outperform rodents and dogs in detecting certain odours, and we can follow scent trails. Smells feature in our choice of sexual partners and in our ability to detect fear, anxiety or aggression in others.
