Although the human sense of smell is feeble compared to that of many animals, it is still very acute. We can recognise thousands of different smells, and we are able to detect odours even in infinitesimal quantities.

Our smelling function is carried out by two small odour-detecting patches – made up of about five or six million yellowish cells – high up in the nasal passages.

For comparison, a rabbit has 100 million of these olfactory receptors, and a dog 220 million. Humans are nonetheless capable of detecting certain substances in dilutions of less than one part in several billion parts of air. We may not be able to match the olfactory feats of bloodhounds, but we can, for example, ‘track’ a trail of invisible human footprints across clean blotting paper.

The human nose is in fact the main organ of taste as well as smell. The so-called taste-buds on our tongues can only distinguish four qualities – sweet, sour, bitter and salt -all other ‘tastes’ are detected by the olfactory receptors high up in our nasal passages.

Click the link below to read more interesting facts about our sense of smell.

This infomation was derived from The Social Intrests Research Centre.