Posted by: Prospector PJ2 OCT 2013
Humans?can detect up to 10,000 different aromas, but a team of scientists has now proposed that these aromas can be grouped into just 10 categories.
Writing in the PloS One journal, they propose that these 10 basic categories reflect important attributes about the world, such as danger, food and so on. The 10 categories they have identified are: fragrant, woody/resinous, fruity (non-citrus), chemical, minty/peppermint, sweet, popcorn, lemon, pungent and decayed.
Any natural scent is likely to be a complex blend of the different categories, say the researchers. They hope to be able to predict a smell based on its chemical structure at some point in the future.
The sense of smell was first explained by Richard Axel and Linda Buck, who won the Nobel prize for medicine for their work in 2004. They discovered 1,000 different genes that control production of specialised protein receptors that are found on cells in the upper part of the nose and detect odour molecules.
These cells are highly specialised. Each possesses only one type of receptor and each receptor can only detect a limited number of scents.
If the sense of smell is reduced or lost, patients are said to have anosmia. This condition can be caused by traumatic head injury or viral infection, be a result of another disorder such as Alzheimer’s disease or Parkinson’s disease, or be a side effect of various drugs, including metronidazole, amiodarone, amphetamines and cocaine.
Research in mice has shown that stem cells in the nose can develop into smell receptor cells. They can be encouraged to do this by removing a gene that codes for a brake on growth in these cells.