If you are lost in the dark, without sight, sound or clue just follow your nose.
The latest olfactory study indicates that when it comes to tracking scent at ground level on open terrain, the average human’s sense of smell is stronger than the majority of people believe.
"There exists general hypothesis that people have rather bad sense of smell," said the lead author of the research, Jess Porter, a Ph.D. candidate in biophysics at the University of California at Berkeley. "However, we discovered that people can definitely sniff their way precisely around a spatial context - though less effectively and more slowly if they have only one nostril to work with."
We are able to navigate by smell
The latest American-Israeli research was published online on December 17 in Nature Neuroscience. It announces that people can, actually, be trained to rely completely on ground level smelling to effectively navigate mysterious territory. Actually, they instinctively mimic several animal behaviors, such as enlisting each nostril to independently identify distinct smells and "triangulate" a path.
Porter joined Berkeley psychology professor Noam Sobel and a group of colleagues. Together, they carried out five experiments aiming at evaluating people’s ability to track scents.
Enlisting anywhere from four to thirty two male and female subjects for the different tests, the scientists had a chance to work in an open field.
How the research was carried out
The participants were blindfolded and ear-plugged, but at first they had been asked to follow a 10-metre trail scented with "chocolate essential oil." They did follow the trial by moving close to the ground on their hands and knees and wearing thick gloves. Only their noses could guide them.
Around 66 per cent of the subjects were able to do so. Nevertheless, when their noses were plugged to cut off the ability to smell, none of them was able to follow the path.
In order to find out whether "practice makes perfect," 2 men and 2 women were then trained to complete the same task three times daily for three days, stretched over a two-week period.
Porter and her colleagues discovered that this kind of training made it possible for the participants to track scent trails quicker and with greater precision. Actually, their speed of completing the task doubled within several days. The scientists are convinced that more training might improve efficiency even higher.
Porter’s team also discovered that as the speed of trained scent tracking rose considerably, so did sniffing frequency. In this regard, they observed that dogs sniff much faster than people, perhaps representing their superior tracking abilities.
Both nostrils necessary
A third experiment demonstrated that each of a person’s two nostrils inhales different smells, pulled from non-overlapping regions in the air. The investigators emphasized that prior research has demonstrated that scent "plumes" in the open are frequently limited to such small areas that only one nostril will pick it up, whereas the other will not.
The fourth test followed up on this finding by asking 14 participants to carry out the field-tracking experiment, but with one nostril taped shut.
Single-nostril tracking was significantly less precise (36 per cent compared to 66 per cent) and 26 per cent slower in comparison with using both nostrils.
In the end, the authors carried out a final test by the use of a special mask that allowed both nostrils to inhale, however forced incoming air to join together into a single air stream inside the middle of the nose.
Porter and her colleagues discovered that this "unified nostril" method was twenty four per cent slower and considerably less precise than tracking completed normally.
This proves that optimal human tracking needs the individual use of each nostril to better differentiate smells as people home in on a proper route.
The scientists concluded that, just as happens with animals, people’s ability to smell can be harnessed to great effect.
Still not eyes
But still, for the vast majority of people, eyes remain the crucial window on the world.
"In my opinion it’s fair to say that humans are very visual, while an animals living in the dark are primarily olfactory," said Porter. "And people have this idea that as our sense of vision and hearing has become so famous, we have lost some of our olfactory abilities."
But this is not the whole story. "We suppose that it’s possible that we don’t place an emphasis on our sense of smell," Porter suggested. "It is caused by the fact that the underlying mechanisms are still there - to a greater extent than we may notice them. And if we place demands on them and educate ourselves, our capability of following a spatial path is able to boost a lot."
George Preti, who is a member of Monell Chemical Senses Centre in Philadelphia, a study institute devoted the science of taste and smell, agreed that humans’ olfactory talents may be honed with practice.
"Our sense of smell may not be as effective as dogs or rodents, but it is still rather sensitive when we use it appropriately," he explained. "I’m a specialist in the chemistry of human odors, and I can tell you that folks that use it for a living, like perfumers, really improve their use of it and make themselves more consciously sensitive to that sort of input."
"Smell is essential in our everyday life," Preti said. "And we use it very often. Not just for assessing food, but also for how we are perceived by the rest of the world. Hence, I’d say that humans definitely do have very sensitive noses – no matter what people might think."
