When someone says ‘you don’t look so good,’ you might want to listen and head to the doctor, according to new research.
Detecting illness is essential to survival from an evolutionary perspective, but it was previously unclear if and how humans could identify signs of it just by looking at one another.
With a particularly bad flu season upon us, symptoms like a runny nose or a persistent cough seem like good potential indicators of who to avoid if we want to dodge the bug.
But researchers in Sweden, the US and Germany collectively found that we are able to tell the difference between a sick person and a healthy one just by looking at their faces.
Composites of 16 pictures of people when they were sick and when they were healthy revealed that drooping eyes and pale skin and lips were the best indicators of who was ill (left)
The annual flu epidemic has already reached widespread status and claimed the lives of a number of people, including at least 12 children.
Reports have been swirling around that the flu shot may not be as effective against this year’s strain, leaving many looking for alternative preventative methods.
The new study, published in the Proceedings of the Royal Society, shows that we might just be able to keep ourselves safe from sickness by searching for physical signs in peoples’ eyes, skin and lips.
Researchers from Stockholm University and New York University injected half of their 22 subjects with a placebo and the other half with a drug that causes brief but notable inflammation and signs of sickness.
Two hours later – just as those given the real injection were starting to get puffy – the researchers snapped photographs of all of the study participants.
The study used two different groups of 60 observers to assess the 16 pictures after eliminating six images from the original batch for being too inconsistent.
Observers with no medical or related training were able to correctly guess that 13 out of 16 of the people whose photos they saw were sick.
Looking back at the side-by-side pictures of sick and healthy people, the researchers identified eight factors that make a person look sick, though, surprisingly, the features most drastically affected by the injection were not the ones that observers most closely associated with looking sick.
Of those eight, three signs stood out as making people look sick.
Pale skin
People tended to think that those with pale skin were the sickest.
Like many of the signs that tipped people off to sickness, paleness is also associated with simply being tired.
Paleness indicates poorer health to animals and humans alike, according to the study authors, who wrote: ‘Redness signals a healthy and attractive appearance in both humans and animals and that appearing tired is strongly related to appearing healthy.’
Hanging eyelids
Sickness can make us feel tired as our bodies work harder to fight off whatever ails us.
Combined with the inflammation caused by the injection the researchers gave them, the sick study participants eyes drooped more than the healthy ones.
However, the study authors acknowledged that this cue was also consistent with the principle that people are ‘less inclined to socialize with individuals who have got insufficient sleep.’
Pale lips
In their comparison between the sick and healthy pictures, the researchers noted that the most obvious difference between the two was the color of their lips.
The sick individuals had noticeably paler pouts than the healthy ones.
Untrained observers, however, completely overlooked this sign, but if you’re trying to spot sickness in the room, don’t forget to check out the mouths.