Smell of success: the human nose beats expectations

A new study has challenged the thinking that we can distinguish between about 10,000 distinct odours, and its findings knock that figure out of the park.

The research asked human volunteers to distinguish between mixtures of odours with varying numbers of shared components.

"On the basis of the results of psychophysical testing, we calculated that humans can discriminate at least one trillion [one million million] olfactory stimuli," write the authors in the journal Science this month. "This is far more than previous estimates of distinguishable olfactory stimuli. It demonstrates that the human olfactory system, with its hundreds of different olfactory receptors, far outperforms the other senses in the number of physically different stimuli it can discriminate."

The findings debunk the belief that humans are terrible smellers and that we have "lost" our sense of smell, according to researcher Prof Leslie B Vosshall from the Rockefeller University. "All of that was based on the erroneous '10,000 odours' numbers," she says.

"Our study is the first to actually put the human nose to the test – we are excited that it is time to revise the textbooks and that this will give a huge boost in confidence for our whole species. It should inspire people to think about smells, spend more time smelling, and actually use our sense of smell."