Rosy cheeks a sign of good health

ResearchBlogging.orgWomen have been wearing makeup since at least 3500 BC. The ancient Egyptians, Romans, and Greeks are all known to have worn makeup, often made from deadly chemicals like mercury and lead. Even today, humans worldwide spend around $20 billion on make up every year, and much of it still isn't good for your skin. What drives humanity's obsession with cosmetics? Why have we literally painted ourselves with poison for over 5000 years?

Ironically enough, it might be to look healthier.

A new study, published in PLoS ONE, found that the redness of facial skin can affect how healthy a person looks.

When you think about it, it makes sense. Researchers have found previously that other species use color to indicate health, reproductive status, and even hierarchy. Often these color changes, like reddening of the face, are due to blood vessels near the skin's surface. In people, sexual hormones have been shown to increase the blood vessels beneath the skin and oxegenate the blood better. People who work out more have been shown to have higher blood oxygen levels, which makes their blood redder. Severe lack of oxygen, a sign of illness, can lead to blue-tinted skin. After all, when you're ill, people often say you look "pale" or even "green".

For that matter, research has shown that the color red is very important to humans psychologically. Women who wear red are considered more attractive, and a woman's lips naturally redden when she's turned on.

What the researchers wanted to know, however, was whether overall redness in the face might affect how healthy a person looked. They didn't just pick any red and any blue to look at, though - they used the colors of oxygenated and unoxygenated blood. In a few different experiments, the scientists asked participants to use computer manipulation to change the overall tone of a person's face until it looked the healthiest, using a sliding scale of the chosen red and blue. In one experiment, the faces they manipulated were from a variety of ethic and cultural backgrounds, so the researchers could see if skin color and tone had an effect. Throughout all the experiments, participants thought that the faces looked best when more oxygenated red was added and worst when more blue was added, no matter what ethnicity the face was.

This means that human beings use skin blood coloration to judge overall health. People who are dominant and have a lot of sex hormones in their systems have more blood vessels beneath the skin, thus better portraying their dominant and healthy status. People who are ill or unfit have fewer facial blood vessels and less oxygenated blood, leading to bluer, unhealthier looking faces.

This is the first time that facial redness has been connected to health and attractiveness in humans. However, it's not the first time skin tone has been looked at. Previous research has found that naturally tanner skin looks better, too, presumably due to the implied healthy levels of Vitamin D that melanin-rich skin ensures. It's likely that a few different cues, from facial coloring to symmetry, are used as signals of underlying health by members of the opposite sex.

What's even more interesting is that the effect of redness was more pronounced in women. The color change had a much larger impact on perceived healthiness in female faces than in males ones, suggesting this mechanism for judging a person's fitness might be mostly aimed at determining healthy females. It's little wonder, then, that women are more prone to makeup use than men. Adding blush to the cheeks is a women's way of trying to look healthier to attract the best mate. Picking the right color rouge for you cheeks is important, too - you have to try and make your face look like there's more oxygen-rich blood running through your skin.

For that matter, getting in shape might do more for you than make you feel good. It might just make you look better, too, in more ways than just a flatter stomach or thinner thighs. Even something as simple as quitting smoking, which would allow your blood to be better oxygenated, might improve how you look to the opposite sex. So if you need even more reason to work out and be healthy, there you go. It'll make you more attractive!

Or, you know, put on blush. It's probably a lot easier than getting in shape and quitting all those bad habits. Just do me a favor - don't tell your doctor I said that.

Stephen, I., Coetzee, V., Law Smith, M., & Perrett, D. (2009). Skin Blood Perfusion and Oxygenation Colour Affect Perceived Human Health PLoS ONE, 4 (4) DOI: 10.1371/journal.pone.0005083


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