Sideways News

Connections between smells and memories may be due to evolution

Whether freshly cut grass or school dinners, there are certain odours that have lodged themselves in our emotional memory, instantly invoking a wave of nostalgia on first whiff.

Now scientists think they may have discovered a biological reason as to why our first smells leave such a lasting impression.

Yaara Yeshurun and colleagues from the Weizmann Institute of Science in Rehevot, Israel, carried out a study on 16 adult volunteers to try to find out why early smells are so evocative.

Whilst showing the subjects objects, such as a pencil or chair, which were unlikely to already be associated with particular smells, they released a pleasant or unpleasant odour.

90 minutes later, they did the same, showing them the same objects but with a different smell.

The following week, they presented the objects to the volunteers and asked them to name the particular smell they associated it. 

Using functional magnetic reasonance imaging (fMRI), they saw that the subjects were more likely to mention the first smell, and in doing so their brains showed a particular activity in the hippocampus region. Their brains did not react in the same way when they chose the second smell. 

Scientists concluded that the brain acted in a certain way the first time someone associated an object with a particular smell, and that such connections that were likely to be formed in childhood, hence the evocative power of our first odours. 

Dr Yeshurun said the "etching" of initial odour memories may be an evolutionary defence mechanism, whereby the brain remembered smells and memories to enhance our ability to sense danger. 

Although further research is needed, the study could pave the way for further investigation into improving memories or helping to erase childhood trauma.

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