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Sniffing out the danger
The human nose has evolved to sniff out the smell of danger, according to research published on Friday.
- The Telegraph Group Limited, London 2008
- Published: 00:16 March 29, 2008
London: The human nose has evolved to sniff out the smell of danger, according to research published on Friday.
Scientists found volunteers who were previously unable to differentiate between two similar scents learnt to tell them apart when given electric shocks alongside just one of them.
They said the findings demonstrate how experiences help sharpen our senses to keep us clear of danger.
The researchers also suggested people with less ability to distinguish between important and irrelevant signals may be more likely to suffer from illnesses characterised by anxiety and vigilance such as obsessive-compulsive disorder.
Lead study author Dr Wen Li, of the Feinberg School of Medicine, Northwestern University, in Chicago, said: "It's evolutionary. This helps us to have a very sensitive ability to detect something that is important to our survival from an ocean of environmental information. It warns us that it's dangerous and we have to pay attention to it."
Twelve volunteers were repeatedly presented with two pairs of very similar grassy smells, which they had previously been unable to tell apart. They received mild electrical shocks each time they were exposed to one scent, but not when smelling the similar one in the pair. Only when the shocks were introduced were participants able to discriminate between the similar smells.
The researchers, whose study was published in the journal Science, then used MRI scans to show activity in a part of the brain called the olfactory cortex changed significantly once a person had learnt to associate a smell with an electric shock.
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