Why do we get used to smells? © iStock

Has our sense of smell evolved based on what is good and bad for us?

Something that smells so rotten surely can't be good for you, right?

Asked by: Tom Russell, Democratic Republic of the Congo

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Yes, we have evolved a higher sensitivity to smells that indicate poison or danger. Rotten fish, for example, smells so disgusting because it’s teeming with bacteria, and we’ve evolved to interpret the odour as a warning that eating the fish would likely make us ill.

It’s true that we become more sensitive to some smells after we learn to associate them with a bad experience. But cadaverine and putrescine, which are produced by decaying corpses, smell revolting even if you have never smelled a dead body before. This aversion is shared with lots of animals and evolved at least 420 million years ago.

Why do some smells cause disgust? © Getty Images

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