L'Oreal : Skin Pigmentation as a Sign of Evolution

Skin is universal. Whether it's light or dark, young or old, its structure is the same from one individual to another... except for two details: its pigmentation and the bacteria that protects it.

This is what researcher Nina Jablonski, a specialist in anthropology and paleobiology, explained during the exhibit 'Dans Ma Peau' at theMusée de l'Homme, in Paris: 'By observing the map of solar radiation, we can see how skin color evolved according to sunlight. It's both a compromise and a great evolutionary story.'

The number of pigments that are found in each skin cell determine its color. These pigments develop depending on where in the world they are. A lighter color helps absorb vitamin D, which is essential for health, while a darker skin tone acts like a natural sunscreen and protects the body from harmful rays.

These pigments act like the skin's protective barrier- but they're not alone. The same role also applies to the skin's microbiome , an ensemble of bacteria that cover the entire body. As described by Bonnie Bassler, a molecular biologist, 'there are ten times more bacteria on the skin than in human cells. That means one person is composed of 10% human and 90% bacteria.' The goal of these 'good' bacteria is to form a protective barrier that limits external aggressions like wind and pollution. If the microbiome is disturbed, the skin can develop diseases and infections.

Research on the microbiome is an optimistic endeavor that could eventually allow us to remedy some of the consequences of aging. 'But for the moment, we're in an observational phase,' concludes Bonnie Bassler. Dermatological research on pigmentation and bacteria still has many secrets to reveal.

> Watch the interview with Fabrice Aghassian to find out more about the evolution of skin throughout the ages!