The human sense of smell works in stereo, according to new research by Stanford University scientists who write about their work in the current issue of Nature.
"To each nostril the world smells differently," according to Dr Noam Sobel and colleagues who found that the flow of air was always greater into one nostril than the other, owing to a slight swelling which alternated back and forth every few hours.
The changing airflow caused each nostril to deliver a slightly different olfactory message to the brain, a system, they said, which enhanced our overall sensitivity to odours.