Pigmentation

Ever wonder why human skin comes in different colors? It turns out that skin color depends on the ratio of two melanin pigments, brown-black eumelanin and red-yellow pheomelanin.

Eumelanin is also extensively present in dark-colored hair, while pheomelanin is present mainly in blond and red-colored hair.

Both these melanin pigments are produced by melanocytes, the specialized cells present in the stratum basale of the epidermis.

In dark-skinned and brown-skinned people, melanocytes produce more melanin than in those with fair skin. Local accumulation of melanin is often seen as freckles and moles.

Prolonged exposure to sunlight often increases melanin production, which absorbs the harmful UV rays in the sunlight, transforming them into heat energy.

However, such a defensive response leads to skin darkening or tanning, often visible on fair skin.

Since people with fair skin produce less melanin, their skin epidermis—the outermost layer of the skin is almost transparent. So, the crimson-colored hemoglobin from the blood flowing in the underlying dermal capillaries renders a pinkish hue on the skin.