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The stripes on humans are named for the German dermatologist who discovered them, Alfred Blaschko. In 1901, he noticed various line patterns on the skin of his patients. Generally, V-shaped lines extend over the spine, U-shaped lines are on the chest and upper arms, and S-shaped lines run across the torso. Additional perpendicular lines go up and down arms and legs, with spirals on the head.
Now known as Blaschko's lines, they are generally not visible to the human eye. They can be seen under ultraviolet light, but emerge with greater clarity in the case of certain medical conditions, mostly dermatological.
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