Humans may lack the scent-tracking sophistication of dogs, but we can still use our nose to sniff our way out of the dark, according to a new study.
This is the first time smell-based navigation has been field-tested on humans. The results evoke a GPS-like superpower one could call an "olfactory positioning system", researchers said.
Researchers from the University of California Berkeley found that like homing pigeons, humans have a nose for navigation because our brains are wired to convert smells into spatial information.
Researchers found that we can find our way blindfolded, towards a location whose scent we have smelled only once before.
"What we've found is that humans have the capability to orient ourselves along highways of odours and crisscross landscapes using only our sense of smell," said study lead author Lucia Jacobs from University of California, Berkeley.
The process of smelling, or olfaction, is triggered by odour molecules travelling up the nasal passage, where they are identified by receptors that send signals to the olfactory bulb - which sits between the nasal cavity and the brain's frontal lobe - and processes the information.
A key to the connection between smell, memory and navigation is that olfactory bulbs have a strong neural link to the brain's hippocampus, which creates spatial maps of our environment.
"Olfaction is like this background fabric to our world that we might not be conscious of, but we are using it to stay oriented," Jacobs said.
"We may not see a eucalyptus grove as we pass it at night, but our brain is encoding the smells and creating a map," Jacobs added.
Pigeons and rats are known to orient themselves using odour maps, or "smellscapes", but humans rely more heavily on visual landmarks.
For the study, two dozen young adults were tested on orientation and navigation tasks under various scenarios in which their hearing, sight or smell was blocked.
The test location was a room where 32 containers with sponges were placed at points around the edge of the room. Two of the sponges were infused with essential oils.
Study participants were led, one at a time, into the room wearing blindfolds, earplugs and headphones and walked in circles for disorientation purposes.
They spent a minute at a specific point on the grid, where they inhaled a combination of the two fragrances. After being walked in circles again for disorientation purposes, they were tasked with sniffing their way back to the starting point.
Study participants navigated relatively closely to the targeted location when using only their sense of smell. Moreover, they were not just following one scent, but using information from both scents to orient themselves toward a point.
The study was published in the journal PLoS ONE.
