Learning to follow your nose described in an article in ScienceNOW 18 December 2006 and New Scientist , 23 Dec 2006, p9.

University of California Berkeley scientists have found that humans can follow a scent trail like a dog and can get better if they practice. The researchers tested 32 people to see if they could follow a trail of chocolate essence drawn along a patch of grass by crawling on the ground and sniffing. Two thirds of them were able to follow the trail. Four volunteers then practiced scent trailing three times a day for three days, and were then able to follow the trail more accurately at a greater speed.

Further experiments showed that the ability to follow scents involves comparing the intensity of the odour between air entering each nostril and from one sniff to the next. The scientists do not believe humans could ever replace dogs in detecting smells. We have difficulty moving quickly close to the ground and have far fewer smell receptors in the nose. The experiments are part of an ongoing study into how the sense of smell actually works.

Editorial Comment: For many years the human sense of smell was written off as an almost useless vestige left over from evolutionary ancestors, but recent research, including the experiments described above, has shown that the human sense of smell works in a sophisticated way, and we have sufficient sense of smell for our needs. (Would you like the world to be any smellier than it is?)

The real test has come when chemical engineers have tried to design systems that can work as well as the human nose for analysing things that humans regularly smell. So far they haven’t succeeded, and perfume manufacturers and food technologists still have to employ people to test products for smell. When they can replace people with artificial noses they will have proven that real human noses are the result of creative design, not naturalistic or chance random evolution.

Evidence News 23 April 2008

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