A rose by any other name would smell just as sweet, but new findings suggest a rose smelled by any other nose would actually smell quite different.

A study in the United States has shown there is a great deal of variation in the arrangement of human olfactory receptors, which results in the same breadth of variation in the way people perceive smells.

Differences of as much as 30 per cent between two people’s olfactory receptor proteins have been identified in a study trying to decode the hundreds of specialised smell sensors.

“Understanding how this huge array of receptors encodes odours is a challenging task,” says molecular biologist and lead author of a new report, Dr Joel Mainland.

“The activation pattern of these 400 receptors encodes both the intensity of an odour and the quality – for example, whether it smells like vanilla or smoke – for the tens of thousands of different odours that represent everything we smell.”

“Right now, nobody knows how the activity patterns are translated into a signal that our brain registers as the odour,” he said.

Just to make it all the more complex, the underlying amino acid sequence can vary slightly for each of the 400 receptor proteins, leading to multiple variants for each of the receptors.

Every single receptor variant responds to odours in a slightly different way, and the variants are distributed across individuals such that nearly everyone has a unique combination of olfactory receptors.

To study olfactory receptor variation and its impacts on how we perceive smells, the team created a series of mini-noses in lab conditions. Their findings bring important new information to the understanding of how the inner-workings of the sense of smell can encode the intensity, pleasantness and quality of odour molecules.

Researchers cloned 511 variants of human olfactory receptors and embedded them in host cells. Each receptor variant was measured for its response to a panel of 73 different odour molecules. Twenty-eight receptor variants were found which responded to at least one of the odour molecules.

Extrapolating from further analyses, researchers predict the olfactory receptors of any two individuals differ by about 30 per cent. Statistically, for any two randomly chosen people, around 140 of their 400 olfactory receptors will smell things differently.

One of the authors said it could lead the creation of the great un-delivered promise of science fiction history; smell-o-vision.

“The long-term goal is to figure out how the receptors encode odour molecules well enough that we can actually create any odour we want by manipulating the receptors directly,” said Mainland.

“In essence, this would allow us to 'digitize' olfaction.”

The full report is accessible here.