Tracking smell? Don't just follow your nose

Research shows that while searching in a familiar area with limited choices, a run-and-scan strategy is more efficient than a tracking strategy.

Kolkata: Hunger pangs attack at night. There's a power cut and its dark. Do you run-and-scan for food in the most likeliest places or do you follow your nose?

Well, research has revealed the former strategy works best in familiar environments. Research by Urvashi Bhattacharyya and Upinder Bhalla from the National Centre for Biological Sciences (NCBS), Bengaluru, shows that while searching in a familiar area with limited choices, a run-and-scan strategy is more efficient than a tracking strategy.

In a recently published paper in the journal eNeuro, Bhattacharyya and Bhalla used rats to study how animals choose navigational strategies when presented with an odour signal.

Dogs, rats, insects and even humans are known to adopt a zig-zag path while tracking smells - a strategy known as 'casting'.

Under natural conditions in large, unfamiliar environments, casting is thought to be useful when animals search using smell-based cues.

But what happens if the animals are placed in a familiar territory?

"We found that rather than casting, rats ran towards a potential target and then serially scanned across other targets till they found the right one", said Bhattacharyya in a statement on Tuesday.

In human terms, this kind of search is equivalent to picking a likely room where dinner could be served, then peeking into different rooms to find dinner if the first choice was wrong - a very different approach to actually using one's sense of smell to pin-point the room with food, the researchers said.

This strategy, the researchers said, seems to assure very good accuracy in locating correct targets.

"Even in the presence of other background odours or air turbulence, the animals were able to identify the correct targets, though they tended to be marginally slower than under normal conditions."