Modern life could be putting health at risk by damaging our ancient sense of smell, a leading scientist claims.
Traffic pollution, uncollected rubbish and messy homes are having a harmful effect on the nose, says Dr Kara Hoover, an expert in olfactory evolution.
She says having an impaired sense of smell increases the risk of mental problems such as anxiety and depression as well as obesity.
Speaking at the American Association for the Advancement of Science annual meeting in Boston, Dr Hoover said: "Our sense of smell evolved in a very rich landscape in which we were interacting regularly with the environment.
"Now today we're not interacting with the environment and we're in very polluted places. Pollution is disrupting our sense of smell.
"That means it puts you at greater risk for things like mental health disorders such as depression and anxiety and it also puts you at greater risk for physical health problems such as obesity.
"It also puts you at greater risk for social health problems - not being able to pick up on social cues from other human beings."
Loss of smell sense was linked to poor mental health in a number of ways, Dr Hoover said.
"People who have suffered from a loss of smell have increased anxiety over their own body odour because they don't know if they smell bad or not," she said.
"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."
Studies had also shown a link between smell loss and obesity.
"If you have an impaired sense of smell you're getting sated more from taste and seeking richer tastes; salty and fatty food," Dr Hoover said.
One study of adults with a very strong sense of smell found they tended to have low body weight.
People from more disadvantaged backgrounds were more at risk because of their greater exposure to pollution, she said.
She wanted to see more "greening" of cities to provide a healthier smell environment.
