HUMAN BRAIN

HUMAN BLOOD*.

HUMAN BONES

Why isn't it the same with our skin color?

THE SCIENCE BEHIND SKIN COLOR

Source: Dept. of human evolutionary biology

Different wavelengths of light are reflected or absorbed by a pigment on the top layer of our skin Melanocyte Melanin MELANIN

Eumelanin Pheomelanin Melanocyte Melanin The more the Eumelanin, the darker the skin

North Pole Arctic Circle 60 N Low Angle of Lin Incoming Sunlight 30 N Tropic of Cancer Equator Sunlight Strikes Sun Most Directly Tropic of Capricorn 30 S 60 S Antarctic Circle Low Angle of Sun Incoming Sunlight Atmosphere South Pole

Arctic Circle 60 N Low Angle of Lin Incoming Sunlight 30 N Tropic of Cancer 50,000 years ago Equator Sunlight Strikes Sun Most Directly Tropic of Capricorn 30 S 60 S Antarctic Circle Low Angle of Sun Incoming Sunlight Atmosphere South Pole

Before After: Incoming UV photon Damage to DNA when skin is overexposed

UVA UVB UVA UVB The melanin in skin determines how protected you will be from the sun

Some of our ancestors who were adapted to the tropic spread to other parts of the world

What happened in the north?

Vitamin In

Risk of Vit D deficiency due to lack of optimal UV exposure