Why do We Tan?

Already in ancient Greece, fair skin was a symbol of high social class. It would be millennia before the typical tanned tone of summer became, by accident and thanks to a famous fashion designer, a symbol of social prestige. It happened in the twentieth century, at the same time as the biological usefulness of a darker complexion also began to be revealed.

Cross-sectional view showing skin tone becoming darker due to the production of more melanin to overcome the damage of melanin caused by UV radiation. Credit: Scientific Animations. 3

Cross-sectional view showing skin tone becoming darker due to the production of more melanin to overcome the damage of melanin caused by UV radiation. Credit: Scientific Animations.

Beyond the aesthetic question, the tan has a scientific explanation—it serves to protect us from solar radiation. Genetics explains that, after many generations, some ethnicities have lighter tones than others, even if it is fashion and cultural issues that determine whether the tan becomes popular or not.

Our protective shield

“Tanning is a biological response to the exposure to ultraviolet radiation,” Ellen Quillen, a researcher at the Department of Genetics at the Texas Biomedical Research Institute (USA), explains to OpenMind.

When we sunbathe, some cells in our skin called melanocytes protect us from damage caused by solar radiation by generating melanin, which acts as a protective shield against the light rays.

This type of radiation causes mutations in the DNA—with the risk of causing cancer—and breaks down nutrients such as folic acid, responsible for making cells function well. It also damages collagen and other skin proteins, which increases the appearance of wrinkles.

“Melanin is produced and packaged in vesicles that are transported and accumulated around cells to protect their DNA from ultraviolet radiation,” says Paola Pasquali, a dermatologist and member of the Media and Public Relations Committee of the European Academy of Dermatology And Venereology.

When we put ourselves in the sun, its rays activate the cells that secrete melanin. This pigment absorbs the radiation and makes us brown. “It’s a defence mechanism,” says Pasquali.

Genes determine the tan

People with darker skin secrete more melanin and, therefore, are less sensitive to this radiation. “The level of melanin in the skin is different in different ethnic groups,” Christine Lind Behrens of the Prevention and Information Unit of the Danish Cancer Society tells OpenMind.

Accordingly, a person can have a skin type of 1 to 6. The 1 will correspond to those very sensitive to the sun (typical of the Nordic countries), while 6 will be associated with people with very dark skin (common in Africa), who barely ever burn. To raise awareness of sun damage to the skin, the Danish Cancer Society and the TrygFonden Foundation have launched the “Help a Dane” campaign.

Ethiopians have very dark skin, secreting much melanin to defend against solar radiation, very high in that region. Credit: Rod Waddington

Ethiopians have very dark skin, secreting much melanin to defend against solar radiation, very high in that region. Credit: Rod Waddington

Experts stress that excess radiation is harmful to anyone. “With enough exposure to ultraviolet rays everyone, no matter how much melanin they produce, will have sun damage,” warns Quillen.

Why is it that one ethnic group is darker than another? It is due to the genetic component, inherited after many generations. Thus a person with dark skin will have ancestors who lived near the equator, where the radiation is very intense throughout the year.

“Over time, natural selection favoured the genetic variants that cause people living in these environments with high ultraviolet radiation to produce a lot of melanin for their protection,” says Quillen. After several centuries, genetic variants were transferred to their present descendants, who may or may not live in the same area as their ancestors.

Chanel launched the tan

Although it is the genetic component that sets a specific skin tone for an ethnic group, cultural issues influence the connotations of these tones. In India, many women, mostly of dark complexion, try to lighten their skin, imitating the Western model.

Haute Couture designer Coco Chanel makes suntanned skin fashionable in the 1920s. Credit: Time/Getty

Haute Couture designer Coco Chanel makes suntanned skin fashionable in the 1920s. Credit: Time/Getty

In other Asian countries like China or Korea, women avoid the sun to keep their skin clear because it seems more beautiful than a tanned complexion. They are also concerned about the risk of cancer, as revealed in a study of Asian women living in Australia.

“In a way it is a cultural issue and also depends on fashion. In India they add something to the sunscreen to make the skin look whiter, while many Danes want to return from their sunny holidays with a tan, “says Lind Behrens.

From ancient Greece, fair skin has been seen as indicative of the high social classes, who did not have to work from sun up to sun down like the slaves, with their more tanned skins. It was the French designer Coco Chanel who, in the 1920s, unintentionally promoted the tan after burning herself on a yacht trip. Thus ended the association of tanned skin with the lower classes.

Since then, the tan has been venerated in the West, with tanning booths, tanning wipes and a wide cosmetic arsenal. Although sunbathing is positive for stimulating the synthesis of vitamin D, it should be done in small doses and always with protection. “The sun of today is the premature aging of tomorrow,” Pasquali reminds us.

By Laura Chaparro

@laura_chaparro