Do you have any sunscreen?

So melanin was recruited, in our lineage, and specifically in our earliest ancestors evolving in Africa, to be a natural sunscreen.

So, living at the equator, we got lots and lots of ultraviolet radiation and the melanin this wonderful, complex, ancient polymer compound in our skin served as a superb natural sunscreen.

For a full year, A.J. Jacobs followed every piece of health advice he could from applying sunscreen by the shot glass to wearing a bicycle helmet while shopping. Onstage at TEDMED, he shares the surprising things he learned.