A human's sense of smell may not match that of his best friend but it deserves greater credit that it gets. A University of California at Berkeley study, aimed at finding if two nostrils are more efficient than one and if their spacing affects the level of olfactory abilities, has found that humans have a stronger sense of smell than previously believed.
Under the study, Jess Porter, Noam Sobel and their team conducted an experiment wherein 32 human subjects were made to follow a 10-meter grass trail of chocolate oil. The subjects were blindfolded and made to crawl on all fours. The trail, which was made using chocolate essential oil poured over a grassy ground, was followed correctly by as much as two thirds of the participants.
Of the subjects who got the trail right, the research team chose four to train for two weeks to see if their olfactory abilities improved with a structured approach like they do in the case of dogs. The team found that such training did indeed help, with the subjects able to chase the trail closer to where it was and faster after the training period. To block the other senses from distracting the subjects, the researchers made them wear blindfolds, kneepads, elbow pads, earplugs and gloves.
“Once people realized that they could do this, they seemed to develop a good sense of how to zigzag their noses back and forth across the odor plume in order to pick up the scent most effectively,” said Jess Porter to
NewScientist.com. Like dogs, the human subjects also marked a boundary around the trail to localize the scent and identify it accurately.
Originally meant to determine if the sense of smell was like the aural one, where the blocking of one ear diminishes the ability to hear, the study found that each human nostril picks up scents in a localized manner. When one nostril of the subjects was blocked, their ability to smell accurately declined, as it did when they wore a system that pooled air taken in from different nostrils into one artificially created nostril.
“Whether mammalian scent-tracking is aided by inter-nostril comparisons is unknown. We assessed this in humans and found that humans can scent-track, they improve with practice, the human nostrils sample spatially distinct regions separated by 3.5 cm and, critically, scent-tracking is aided by inter-nostril comparisons,” the researchers wrote in a report published in the journal
Nature Neuroscience. “The poor reputation of human olfaction may reflect, in part, behavioral demands rather than ultimate abilities,” they added.
Perhaps the biggest problem faced by humans while tracking a trail using the olfactory senses is their failure to get closer to the ground. Since crawling does not come naturally to humans, the speed with which they identified the trail improved with training, felt the researchers.
“We interpret these results to suggest that, as subjects increased their speed, it was necessary for them to sniff more quickly to get the same quality of information. We found that not only are humans capable of scent-tracking, but they spontaneously mimic the tracking pattern of mammals,” Noam Sobel was quoted as saying.
