On Wed, 07 Feb 2018 17:09:48 -0800, allisellis851 wrote:

+AD4 The amount of Sunlight over generations affects the pigment, changes
+AD4 skin color.

The thinking now is that people moved from Africa north to Europe and
west to Asia.

People rely on sunlight to synthesize vitamin D, which is needed for
healthy bones. This is a particular problem for growing children.

There's always some variation in skin color, even within families, and
the lighter skinned people could establish communities further north.

And that's the story.