 Okay, I think there's something that is important to talk about that I probably should have talked about in the last one, which is what is like, wait, we have like, what's the end game of the melanin that gets produced, it gets engulfed by these keratinocytes, they engulf the melanosomes, but what is the melanosome actually doing in the keratinocyte? And I want to say this out loud so that you have a sense that there is an adaptive value to melanin production. The melanin, here's my little melanosome, okay, that gets engulfed, it's full of melanin, right? It goes and finds the nucleus where your DNA is, another macromolecule, DNA super important provides the instructions for building proteins that are you. The nucleus gets shaded by the melanosome. So basically, this is what I envision happening, I envision this melanosome flattening itself out and forming like a little umbrella, a nucleus umbrella, full of melanin that protects the nucleus of the keratinocytes from our amazing glorious sunshine, two reasons why that could be valuable. The ultraviolet rays from the sun can damage DNA. There is a hypothesis that perhaps the melanin serves a function in protecting the nucleus, the DNA from damage from the sun. Also, in as part of nuclear function, a B vitamin is necessary for DNA function. And that B vitamin can be broken down, I can't remember which one it is, but it can be broken down by the sun, by the UV light. And so the melanosome provides an umbrella to protect that B vitamin and allow it to keep on functioning. And I can't remember if that's the B vitamin involved in energy or if it's involved in protein synthesis, but it's an important one. The key take home is that this melanosome, the melanin has a protective function and it's valuable. It has worth in our skin, it's protective. So I'm not going to talk about how that came about, the current state of the research. I've got some really interesting papers that you can read, some really interesting books that you might look into. But the thing that I want to look at is, well, where does the variation come from if everybody has the same number of melanocytes? And I'm reluctant because this is getting into something that's a little bit tender. I am showing you a skin color chart that's used in an activity done by the, or provided by the Exploratorium, which is a hands-on science museum in the Bay Area. Super awesome, super fun and interesting. And they've created this like paint chip like thing for kids to explore the different shades of their skin. And what kids discover in, and we all discover in playing with this is that not only do you have different colors of skin on different parts of your body, you have different colors of skin at different times of the year, right? We tan. And in fact, UV light activates melanocyte function. So the more UV light you're exposed to, the more melanin you're going to produce. That's how you end up with a tan. And the less UV light you're exposed to, then your body goes back and says, hey, I don't need as much melanin in this situation anymore. And there goes your tan. So trying to think about anything essential about the amount of melanin in your skin is scientifically not well-founded and not the aim of showing you this variation chart. The thing I want to talk about is how do we get those, how do we get that different, how do we get difference? How do we have variation if everybody has the same number of melanocytes? Because that would be my guess, that some people have more melanocytes and some people have less. But the fact is, since we all have the same amount, there are three ways. And these are genetically indicated ways for you to end up with a different amount of melanin in your skin. First, melanocytes can produce differing ratios of pheomelanin to umelanin. Let's write that down. I'm just going to summarize. Different ratios of pheomelanin to umelanin. And pheomelanin is lighter, sorry, I'm writing with my highlighter. And umelanin is darker. So the actual melanin color, like they say, umelanin is like black-brown pigment molecule. And pheomelanin is reddish-orange-ish pigment molecule. So the melanocyte is busting a move, producing different amounts of one or the other. Does that, did you follow what I was just saying? I'm going to assume the answer is yes. And I'm going to move on to the next thing, that the next difference that is genetically coded, melanosomes, melanosomes, okay, remind yourself, what was a melanosome again? The bubble, right? The melanosomes can vary in fullness, oh good God. So you can produce your busting a move, you're producing the ratio of pheomelanin and umelanin, and you make really, really amazing full melanosomes, I almost said sites, melanosomes, the bubbles are full or not so full. If they're not so full, there's not as much color, there's not as much pigment. The pigment's going to be different if you have less full melanosomes. If you have really full melanosomes, the pigment is going to be different. That's the second way that we can vary the skin color that you have. And then everybody has the same number of melanosome, melanocytes, everybody has the same number of cells, but you can, those cells can produce different amounts of melanosomes. So sites produce different numbers of melanosomes. So the melanocytes can be really, really active and make gobs and gobs of melanosomes, and that's going to produce all this pigment. And those melanosomes can be really, really full or not so full, but you're producing a bunch of them. Or you can produce not very many of them. And if you don't produce very many of them, then you're not going to have as much melanin in your skin. Same number of melanocytes for everybody. It's fascinating, the research on where you live and vitamin D and like what are, I mean, there's all sorts of really interesting research on skin color, variation in skin color. But to me, there is, it's super interesting how simple it is and how valuable melanin is. If I were a nucleus, I'd want an umbrella and I probably would want many umbrellas and I'd want lots of different colors of umbrellas. So, that's handy. Okay. You have all the science, my friends, and now I'm going to do one last bit because I don't think we can talk about melanosomes, melanocytes, skin color without talking about racialized identity.