Follow your nose, it probably knows

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Humans have a far greater sense of smell than previously thought, but daily showers and fridges, which mask bad odours, have reduced our ability to detect scents, scientists believe.

It had been estimated that we could smell 10,000 odours but now, researchers say, it is more like one trillion.

Experts believe our sense of smell is much closer to that of animals than we imagined, but we no longer pay attention because smells are often hidden, meaning important sensory information is lost.

"Humans have not lost their sense of smell. We are just not aware of how good we are at smelling and are just not using this sense to our full potential," said Leslie Vosshall, one of the authors of a report at Rockefeller University in New York.

"Our paper shows that humans have a dramatically better sense of smell than previously assumed."

Our sense of smell evolved over millions of years and our human ancestors would have used it to spot disease, avoid rotten meat and poisonous plants, and to sniff out food.

However, as we assumed an upright posture, this lifted our noses far from the ground where most smells originate, diluting scent molecules in the air.

Today many smells which still give us hints about rot and poor hygiene are masked behind perfumes, air fresheners and deodorants.

Researchers said this could explain why people believe that smell is unimportant, compared to hearing and vision.

Many studies have shown that pheromones emitted from the sweat glands play an important role in physical attraction.

Dr Craig Roberts, a senior lecturer in psychology at the University of Stirling, said: "We all use smell more than we realise, sometimes in ways we don't think much about, such as when choosing partners."

The study was published in the journal Science.