The modern world is ruining mankind's sense of smell and making people crave salty and fattening food, a leading scientist has said.
The harsher smells caused by pollution, uncollected rubbish and even messy homes are corroding our ability to detect the nuanced hues of nature and are making people ill, according to Dr Kara Hoover, an expert in olfactory evolution.
She told a meeting of the American Association for the Advancement of Science in Boston that those with an impaired sense of smell are more likely to be obese because they tend to prefer richer-tasting food. They are also at higher risk of mental health problems such as anxiety and depression.
"Our sense of smell evolved in a very rich landscape in which we were interacting regularly with the environment," the Durham University academic said. "Today we're not interacting with the environment and we're in very polluted places."
A poor sense of smell also affects people's ability to taste, which means that they are likely to seek out stronger tasting food, which is very often salty and fatty.
By contrast, people with a powerful sense of smell are more likely to have lower body weight, previous research has indicated.
Those who have suffered from a loss of smell often have increased anxiety over their own body odour because they don't know if they smell bad or not, Dr Hoover said, adding: "They're anxious about not being able to smell danger like gas leaks or smoke.
"They suffer from poor quality of life and depression because they're no longer engaging with food or loved ones in terms of their sense of smell." She said this anxiety increased the risk of developing more serious mental health issues.
Research this month also suggested that diesel pollution could double the chances of developing dementia.
Poor air quality has already been linked to a higher chance of suffering a heart attack or stroke. People from poorer backgrounds are in general more exposed to pollution, with bus passengers confronted by eight times as much as car drivers. Those living in dirty areas or where rubbish is not collected regularly are also more likely to suffer damage to their sense of smell.
Dr Hoover told the Boston meeting that she wanted to see more "greening" of cities to protect people's sense of smell.