Remember how Mom could tell you were sick just by looking at you?

Scientists are now discovering our mothers might have been on to something…

A new study published by the Royal Society observed that humans can spot signs of illness just from a brief glimpse of someone’s face, even just hours after they’re infected.

Scientists at Stockholm University are saying we can use a number of facial cues to judge the health in other people and maybe avoid getting sick ourselves.

Dr. John Axelsson, a co-author of the research and a professor at the stress research institute says they have found that signs of a person being acutely ill – such as pale lips, a downward turn of the mouth and droopy eyelids – are visible just hours after being infected, even before they know themselves that they are ill.

The latest study highlights the ways in which humans might use a host of early signals to avoid contracting infection from others.

Writing in the journal Proceedings of the Royal Society B, Axelsson and colleagues described how they injected 16 healthy adults with a placebo and, at a separate point in time, molecules from E coli which are known to rapidly trigger flu-like symptoms.

The participants were unaware which injection they had received, and were photographed about two hours after each injection.

The team then showed the portraits to 62 participants who were asked to judge whether the pictured person was sick or healthy.

Participants were able to tell a sick person from a well person with an accuracy rate of 70 percent.

To delve even deeper, a new group of 60 participants were shown the photographs, without being told which injection had been given.

Individuals photographed after being injected with the E coli molecules were, on average, rated as looking more sick and more tired than in photos taken after they were given the placebo. They were also rated as having a more swollen face, redder eyes, less glossy and less patchy skin as well as a more drooping mouth, hanging eyelids and – in particular – paler lips.

Professor Ben Jones of the Face Research Lab at the University of Glasgow welcomed the research. “This study adds to growing evidence for the existence of facial cues associated with acute sickness and help us understand how, unfortunately, social stigmas about people suffering illnesses might emerge,” he said.

Dr. Rachel McMullan of the U.K.’s Open University said that it would be helpful to look at whether the results held for a wide range of ethnic groups and for different diseases, but added the results suggested ill individuals could be spotted soon after infection.

“Being able to quickly identify and avoid potentially sick, contagious individuals will certainly be an evolutionary advantage and this study is a good starting point for further research into the how we detect early signs of infection,” she said.