It gets its color from two types of melanin: brown-black eumelanin and red-yellow pheomelanin.

棕素和红褐素。

You need a lot of eumelanin to absorb UV rays.

你需要大量素来吸收紫外线。

It comes in two broad varieties — eumelanin, which is responsible for the black and brown colours, and pheomelanin, which lends the skin and hair yellow to reddish hues.

素有两大类——素和非素，前者使皮肤和头发呈和棕，后者使皮肤和头发呈和红。

Over the course of generations, humans living at the Sun-saturated latitudes in Africa adapted to have a higher melanin production threshold and more eumelanin, giving skin a darker tone.

数代之后生活在阳光充沛赤道地区周围非洲居民进化出了更高素产生阈值，同时分泌出更多素加深了皮肤调。

There's eumelanin, which gives rise to a range of brown skin tones, as well as black, brown, and blond hair, and pheomelanin, which causes the reddish browns of freckles and red hair.

一种是素，负责形成一系列棕调皮肤以及棕和金毛发，另一种是褐素，负责形成红棕雀斑与红毛发。