On a serious note, does anyone have any logical ideas of why the African American people of the US seem to be getting lighter over the decades?

For some time viewing vintage photos in history blogs, and book that were taken 1950s and earlier, the African Americans in them seem to be more the same color and darker in pigment than African Americans of today. I remember when I was a child my mother and her friends would describe certain people, usually men, as blue-black, because they were so dark, they picked up highlights off the blue sky. When I see ads, and articles today, at least to me, it appears the African Americans in them are lighter in appearance.

My kid brother is lighter in color than I, my niece slightly lighter than him, and her kids are way lighter than any of us. It seem as the generations go forward the family is being “lightened” up. I have my theories, which I would hold for now, as to not taint or direct the conversation on possible reasons why it might be. If you are older and have been around before the 70s, has it been anything you noticed? Please, lets keep the conversations civil and focused. Question might move to social.