Andrew Huberman· PhD
And the melanocytes are the cells that create pigmentation of the skin. And of course there is wide variation in the degree to which there is pigmentation of the skin, which has to do with genetics, also has to do with where you were born and raised, how much light exposure you have throughout the year, right? So people toward the equator tend to have more melanocyte activity than people who are located at the North Pole. And of course, people live at different locations throughout the Earth, regardless of their genetic background or where they were born. And so, as you all know, with light exposure, those melanocytes will turn on genetic programs and other biological programs that lead to enhanced pigmentation of the skin, which we call tanning. The way they do that is by absorbing UV light specifically.