Ologies with Alie Ward - Melaninology (SKIN/HAIR PIGMENT) with Tina Lasisi

Episode Date: February 16, 2023

Skin color! Hair texture! Biological anthropology! The incredibly informed and infectiously funny Dr. Tina Lasisi joins to chat sunscreen, ashiness, redheads, light skin, dark skin, in-between skin, beards, UVAs, UVBs, shower habits, cultural colloquialisms, vitiligo, melasma, medical math, ocher, freckles and more. Dr. Lasisi is about to become your new favorite science communication and internet friend. Also: sunscreen, people. Follow Dr. Tina Lasisi on Instagram, TikTok, and TwitterVisit Dr. Lasisi’s websiteA donation went to The Fieldwork InitiativeMore episode sources and linksOther episodes you may enjoy: Plumology (FEATHERS), Nephrology (KIDNEYS), Trichology (HAIR),  Cnidariology (CORAL), Kalology (BEAUTY STANDARDS), Scotohylology (DARK MATTER)Sponsors of OlogiesTranscripts and bleeped episodesSmologies (short, classroom-safe) episodesBecome a patron of Ologies for as little as a buck a monthOlogiesMerch.com has hats, shirts, masks, totes!Follow @Ologies on Twitter and InstagramFollow @AlieWard on Twitter and InstagramEditing by Mercedes Maitland of Maitland Audio Productions  and Jarrett Sleeper of MindJam MediaTranscripts by Emily White of The WordaryWebsite by Kelly R. DwyerTheme song by Nick Thorburn

Oh, hey, it's the last person who sat on that velour couch and left a butt print. Annaly Ward, we're back to talk pigments and skin and sun and soap so, so, so much. Okay. So thisologist studied biological anthropology at Cambridge, got a PhD at Penn State, and is currently doing a postdoc in quantitative and computational biology at USC, University of Southern California. And she hosts the PBS Digital Studios series, Why Am I Like This? Which has the best title ever.

And starting this fall in 2023, she's going to have her own lab as an assistant professor of anthropology at the University of Michigan. So while she was in LA, she came over one afternoon to sit on the couch and chat, melaninology, melaninology, which yes, I did find examples of this word used in published work to describe the study of biological pigment. And the root means dark, and we're going to get right into it, but first, thank you to everyone who supports the show at patreon.com slash ologies. You can join for a dollar a month.

You can send in questions for the episodes. Thank you to everyone wearing ologies merch from ologiesmerch.com. We have also kid-friendly episodes available. They're called Smologies. Those are linked in the show notes. And thank you to everyone who rates and subscribes and leaves reviews. I read them all, all of them, such as this fresh one from Kitty to Cat, who called the show just the gosh dang best and said, how many different times can a science podcast

make me cry? I don't know, but ologies is helping me find out. That's what I'm here for. Let's cry about science a little bit, but mostly for the most part, we don't cry that much. Also, Mr. 223045 did a bunch of sevens, who left a review about how the playback kept jumping around in the last episode, just FYI, that's not the episode. That is just y'all's internet connections.

So it's just buffering slow. So if you think that editing is skipping around, just hang on, download the whole thing. If you're in spotty Wi-Fi or service, and then it'll be smooth sailing, I promise. We would not put an episode like that. We love you too much. Okay. On to the episode. Oh, you're going to love this one.

Grab a hat and get ready for dark skin, light skin, in-between skin, ginger locks, beards, screen UVAs, UVBs, shower habits, cultural colloquialisms, medical math, ochre freckles, and so much more with biological anthropologist, who is just a hoot. Oh, you're going to love her. Science communicator and soon-to-be assistant professor, melanologist Dr. Tina Lassisi. Hello, my name is Tina Lassisi, and my pronouns are she, her, hers, and Dr. Tina Lassisi. So Dr. Lassisi was the first black student to graduate with a PhD in anthropology from Penn State University after she presented her PhD defense about a year and a half ago.

How was your defense? My defense was really great, actually. It was awesome, and I'm so grateful for that because I hear so many horror stories of basically being grailed and publicly humiliated, but it was just such a lovely event where I got to tell everyone my story. It was on Zoom. I was actually happy that it was on Zoom because that meant that all of my friends and family from overseas could participate equally to anyone who would have been in person.

And I got to tell everyone, this is the wild ride that I've been on for the last six years, and it was great questions at the end. My committee afterwards was just like, yeah, so we're going to ask you a really difficult question. What are your plans next? God bless them. They were great. They were great.

It was just such a beautiful way to end six years of research. What was your dissertation? My dissertation was on the genetic architecture and evolutionary function of human scalp hair morphology. How did you get to the point where you were like, okay, I want to study scalp hair morphology in all of the things in biological anthropology? Did you go through different kind of maze to get to that particular dissertation or was there like a broader area that you really loved?

Okay, buckle up. I'm going to tell you a whole story. Okay. So basically gag is I wasn't even planning to go into biological anthropology. So trust me, it's going to make sense. Okay. You have my full attention. But when I was very young living in the Netherlands, we had Cambridge English Dictionary.

And I remember asking my dad, what's the Cambridge? And he like brought me there when I was 12 and I went, I was like, oh my God, it's like Harry Potter. And I had decided then in there when I was 12, like, you know, I need to go to this university. I want to go to Cambridge. I want to have my Harry Potter experience. I didn't know what I wanted to study there. And throughout my youth, I had known I was always interested in culture.

So I'm Bulgarian, Nigerian. I was born in Bulgaria, lived in like Switzerland, grew up mostly in the Netherlands. So basically like so used to being in between cultures that it felt like such a thing for me. I was like, okay, I love learning about like different cultures. I was really interested in Japan, but I was like, instead of Japanese studies, what if we did something that allowed us to look at more cultures? And I was scrolling through the, you know, course options and they had this thing called

archaeology and anthropology. So I was like, huh, what is that? Like I read through it and basically they were like, you can study archaeology, cultural anthropology and biological anthropology. And I was like, oh, you know, cultural anthropology sounds like fun. I don't know about the other two, but that one sounds good. So I went there to Cambridge thinking that I was going to be a cultural anthropologist, which made sense because like I wasn't really a science person.

I loved like, you know, people. And then I was in this lecture on human biological variation in the first year where they talked about skin color. And I saw, you know, this very well-known set of maps that we often show people of the distribution of ultraviolet radiation around the world and the distribution of skin color around the world. And it's like, do you see, oh, yeah, that makes sense. And for more on this, you can see the 2010 study, human skin pigmentation as an adaptation

to UV radiation, which was published by Dr. Nina G. Giblonsky. So I saw that and it really blew my mind. I was like, wow, I have always been aware of the fact that, you know, people have different skin color, but I never thought about how it was patterned around the world. And so that made me think like, oh, okay, what about other traits? How do those vary? And why did those evolve? And my immediate question as a black woman was, okay, what about my hair?

Like, okay, I understand why my skin is brown, why is my hair curly? And the wild thing is that there wasn't a good answer. What should have been like a really quick Wikipedia search that satisfied my curiosity became this rabbit hole where I basically had this postdoctoral fellow who was at her college who took me under his wing and was like, hey, let's talk about bioanth. And I was like, oh, so I have all these questions and I can't find anything about like hair. And he basically was like, well, sounds like that could be something for like your undergraduate thesis.

And as an undergrad, like I decided, okay, let me get hair samples and like measure them. And like, yeah, long story short. Maybe this thing that should have been a short Wikipedia search ended up being a decade plus journey into understanding this trait and like why humans have it. Does that mean that when someone goes to Wikipedia in the future, they find your stuff? I mean, they better cite me. They better. I mean, fairness step number one is like, you know, let me also finish up publishing

everything. If my advisor is listening to this, I'm sorry, I'm working on the paper. Hey, you just got a PhD. You'd come on fresh. And now you mentioned this map that was a really big eye opener for you. Most people haven't taken those courses. And normally I'd be like, okay, I'd go and I'd look at the map, I do an aside and I'd explain it.

But since you're here, how do you describe that map and what you got from it? Yes. Basically, the way that I would describe it is you look at the map of ultraviolet radiation. So ultraviolet radiation, it's why you wear sunscreen, right? You know, a lot of people are like, oh, UV radiation, wear sunscreen for that. So that's basically what you need to think of. It's like something that can affect your skin and actually your DNA if you're exposed to it too much.

However, it affects you differently depending on how much melanin you have on your skin. And so you look at this distribution, this world map where closer to the equator you have higher intensity of solar radiation. And further from the equator in general, the pattern is less UV radiation. The exceptions are if you live in a very high altitude place and if you've ever been hiking and gotten sunburned while you've been hiking in a mountain, then you know that that's the case. That makes sense.

And then there are some places very far up north in the Arctic where you can have a little bit more solar radiation. But that's generally the pattern closer to the equator. More UV radiation further away, you have less. Then you look at the distribution of skin color around the world and you see the same pattern. You look at close to the equator and you see, OK, people who live in these regions seem to have darker skin than people who live further away from those regions.

And what's pretty significant about that is that we might think of it as, oh, well, in Africa they have dark skin, in Europe they have light skin. The pattern's actually more complicated than that because within Africa you see that closer to the equator, populations have darker skin than African populations who are further from the equator. They're all African populations, but they're all adapted to the UV radiation there. And what's more is that you have populations across Asia, across the Pacific, the Americas that are close to the equator, who have skin that is as dark as many African populations

that are close to the equator. And so from the perspective of a discipline that's really interested in human variation and that has unfortunately contributed to ideas of race and this idea that there are different types of people, this directly challenges that. It tells us that human variation is structured in a way that is much more complex than saying there are three types of people, Africans, Europeans, and Asians. Absolutely not. It's much more complex than that.

And so for me, that's really what it gave me. Remember that 2010 study I mentioned with this map? So the author, Dr. Nina Jablonski, also happens to be an anthropologist at Penn State and Dr. Lassisi has now co-authored papers with her. Absolute boss move, a joy to witness, but yes, this anthropological work changed so much for her. A lot of us, I mean, I would say most of us, we grow up learning how to categorize people, and whether it's by ideas of sex and gender and ethnicity and race, we are socialized

to think, okay, if you see this, this, and that, you put a person in this box. If you see this, this, and that, you put them in that box. And seeing this map or these two sets of maps broke those boxes for me. I was like, huh, okay. And it made me really think about why. Why does this variation exist? Instead of necessarily immediately thinking we need to ignore differences because differences are bad, it brought it into a new light.

It said, okay, there are differences. And like how those differences are distributed is like really complicated, and it has a really interesting story that tells you something about history, big history, evolutionary history. And so that to me was like just super cool. And is anyone studying what's happening since cars and planes and boats? Because it's relatively recently that we've gotten around so rapidly, you know? I live in California, the sun beats down on my face all the time. I have not a lot of skin pigment, mostly Northern Italian and British.

What's happening as we move around in climates that we maybe didn't evolve in? That is a great question. So in general, the thing about evolution is evolution by natural selection, and that's really what we're talking about. When we say you're adapted to a particular environment, the idea is that over multiple generations, individuals have traits that fit the environment better. And by fit the environment better, meaning you thrive more in that environment. A lot of times when we ask questions about people having a mismatch between whatever

trait and their environment these days, it has to do with the fact that there's been too short of a time for there to be a difference. And so looking at something like skin color, for example, a lot of times I get this question of, oh, well, I have ancestors from this region, and it doesn't match what you say is expected by the map. Of course, like if we think about places like the US where we know that people came there pretty recently, it's not going to fit those expectations because there haven't been enough generations for natural selection to act on it.

And it's not just that there haven't been enough generations, it's that since humans have had culture and have developed all kinds of technologies to stop natural selection from taking out those of us who aren't really a great fit for the environment, it's been a thing that has stopped us from being shaped by natural selection as much as we may have been 10,000 years ago, 20,000 years ago, and so on. Do you have some sunscreen? In general, what I would say you need to focus on and think about is how can this affect reproduction?

Evolution, at the end of the day, is who has babies and who doesn't. Yeah. It's really that simple. It does not care how happy you are. It doesn't care. It doesn't care about anything else. It doesn't care how happy you are. It doesn't care how healthy you are even, right?

So a lot of people are like, oh, well, if evolution is supposed to make us better adapted, why do things like cancer exist? And why are some people balding? And I'm like, well, tragically, evolution doesn't care about you post-reproductively. That means have you had babies? Done. Yeah. That's it.

You can die now. It's pretty harsh. It's pretty harsh. But evolution be like. It's okay. I don't care about you anymore. Literally, it's like fuck off and die in that order. That is all that matters.

And so what's actually really interesting is when we talk about fitness and even today with all of the culture that we have, there are going to be various factors that affect people's fertility, their fecundity. Don't ask me exactly what the difference is between those two. I think fertility is like how many surviving offspring you end up having versus fecundity is the ability to actually have kids biologically. So this is correct that fecundity rate worldwide of childbearing peoples is 20 children. That's how many children you can make if you can make them.

But the actual fertility of birthing people, two children, at least in the US. So it's kind of a can versus a will situation. But you know what? After six or seven, they really start raising themselves. Am I right? I don't know. But those things, if they are affected by anything, it doesn't matter like what else it does to you.

That is going to affect how many descendants you have. And at the end of the day, that's all that evolution is really about. And okay, UV, UVA, UVB, does our skin care or know the difference? UVA is associated with more like immediate erythema or redness like in the skin. And that immediate kind of like sunburn and there's actually different types of tanning. So there is the tanning that you have immediately after being exposed to like UV radiation and UVA radiation, where you go into the sun and you're a little toasty, you're a little toasty and it can like fade pretty quickly.

So that and the redness can fade quickly. And you have UVB that's responsible for your more long term tan. So like if you go to tan over like, you know, multiple days, it stimulates your melanocytes to start making more melanin. And that is like tan that stays for longer. That UVB is also responsible for converting this precursor to vitamin D to its active form. So in a way, like I like to say that, you know, humans also photosynthesize is just like something different that we photosynthesize.

And that is one of the reasons evolutionarily that it is beneficial to have less pigmentation where there is less UV radiation overall, because as great as it is to be protected from UV radiation, we actually need some of it to make vitamin D. And so there you go. We have this like careful balancing act that occurs whereby in some places the UV radiation is so strong that it damages your folate, which is like another nutrient that's really important for healthy pregnancies. If you don't have a healthy pregnancy, you don't have a healthy baby.

You lose that evolution. Yeah. So boom, we don't like that. So UV radiation can lower folate levels and lead to issues in fetal development, but not enough sun penetrating your skin and you get low vitamin D, which can happen to more pigmented people who live in cloudy areas. So if you're feeling sluggish or tired, losing hair, maybe losing sleep, say, hey, doctor, why don't you do me a solid and check my vitamin D before I cry on you?

That's how I'd phrase it. But there's a lot of reasons why you need enough vitamin D as well that affect your health. So that's the other thing that you have to play around with. And that's why we see this, you know, really impressive, close fit around the world with the skin color that people have when their ancestors have stayed in a place long enough. It's like, it's, wow, it's like, you're optimized for this. Like you're protected enough, but also letting through just enough radiation so you can make enough vitamin D.

And so without that vitamin D these days, like if you're not going out into the sun or maybe you work in the night shift and you live in a basement, what happens if you're not getting vitamin D from the sun? So a lot of things happen and we're actually still actively learning what the consequences are. And what's really funny and funny, not ha ha, but funny tragic is that there are plenty of people who are honestly almost translucent who are vitamin D deficient. Look, even if you have no melanin, like, you know, you can not be getting enough sunlight, that is possible.

And so there's effects on mental health, there's effects on the immune system. There's all kinds of things and they're still learning. They're associating like vitamin D with like so many different things. I think some people were also making some associations with how people were able to fight off COVID infections, like as a more recent example. So one November 2022 study titled Association Between Vitamin D Sublimitation and COVID-19 Infection and Mortality notes that half of the US population is vitamin D deficient and that vitamin D deficiency is associated with a crappy immune system

and more infections and that folks with lower vitamin D levels experience higher rates of COVID-19. So in this study, military veterans with low baseline vitamin D showed the largest decrease in COVID-19 infection after they got supplements and black veterans had even greater COVID-19 risk reductions with supplementation than white patients. So vitamin D, if you have darker skin, or if you live at high latitude during the winter, if you're a nursing home resident, if you're a health care worker or a nocturnal goblin, maybe you're scrolling TikTok until dawn. You might want to look into it with a doctor who is not a podcast host.

But it is intimately involved in a lot of physiological processes, it seems. And now getting to melanin. Yes. Exciting. Melanocytes. Are there different types of skin pigment? Is it all melanin? Are there different types of melanin? Are there different shades of it?

Or is it just a quantity thing? My ears are open. OK, so melanin is super complex and super awesome. So melanin isn't actually one distinct, coherent thing. It's melanin's plural. It's like a class of chemical structures that have certain similarities. And one of the main distinctions that we can make is you melanin versus pheomelanin.

If we're looking at humans, those are two kinds of melanin that we have in our body. And so you melanin is a type of brown, black pigment that is what's responsible for the range of variation from light to very dark colored skin and, you know, light blonde hair to dark, you know, pitch black hair and, you know, all our eye color and all that good stuff. There's also pheomelanin. Pheomelanin is like this orange, yellow, reddish variants of melanin that is most obvious in redheads.

Like that is a different kind of melanin that has like this different color. And so there are a lot of differences in the two kinds of melanins. But even for both of them, we don't know the definitive chemical structure of melanin. You know, that is a thing that always like surprises me. It's a polymer that we don't really understand. So it has like a bunch of units that are repeating in a way that people haven't. Like we don't know what the final form is.

It hasn't even reached its final form yet. I'm still evolving. And it's the same with pheomelanin. And so that to me is something that's always like impressed me. I'm like, wow, it's like so complex that we don't really even know its structure and it's inconsistent. And so there could actually be a lot of sub variants of melanin. But in addition to melanin itself, we need to think about how it's packaged.

Right. So melanin is made by melanocytes. And it's usually in these little vesicles called melanosomes. So in these melanosomes, you have a bunch of chemical processes that occur that create melanin. So you start with various precursors that go through this huge number of processes where you end up with either you melanin or pheomelanin. And depending on the pH in the melanosomes, you get a different balance of you melanin to pheomelanin.

So this is something that we've learned. It's that all these melanocytes, they make both you melanin and pheomelanin. So it's something they call mixed melanogenesis. And in certain cases, like if you have a certain variant of some genes, like MC1R, it's like a very important gene for pigmentation in general. If you have certain variants, it switches something whereby your final product is way more pheomelanin than you melanin. And that's why some people have red hair.

But in other cases, it can completely shut things down. And that's where we have certain kinds of albinism. And you can also have a lot of it where you can have just a lot of you melanin at the end. So that is something that I think is pretty, pretty magical. Complicated, messy and quite wonderful. OK, so it's not just a matter of amount, but it's also different variations. What happens with freckles? Oh, freckles is a great question.

So with freckles, basically what you have is like a combination of uneven distribution of melanin with more pheomelanin. So in general, our skin color is mostly a question of you melanin. But people with red hair often have freckles as well. So it seems that some variants of MC1R is mostly what we think of. Also affect your skin in a way where you can have basically this patchy structure of what we end up calling freckles. So you can call freckles aphelides if you're a doctor or if you're trying to impress one.

And that word comes from a Greek term, meaning rough spot, which studs the face. And I think maybe the ancient Greeks were a little jealous of how hot people with freckles are. I don't have freckles, but I have blackheads and no one tries to fake those with henna and a tiny paintbrush. Oh, and if you have real freckles, those are caused not by more melanocytes in those areas, but just an increased production of the actual melanin granules or the melanosomes in response to UV radiation.

And once again, there are a few types. So UVA radiation makes up 95% of all the UV rays that hit Earth. And UVA, that shit can pass right through glass. It hits deep within the skin. And that is what they blast you with in tanning beds. And it makes you tan, but also wrinkly and saggy. And when combined with UVB rays, potentially full of cancer. So the UVB rays, they're higher energy, but they don't penetrate.

The skin is deeply, but they can damage the DNA of your skin. They can lead to melanoma and other flavors of skin cancer. UVB can also cause cataracts. And the best way to avoid UVB rays is to just hide under the porch from 10 a.m. to 2 p.m. when they are the highest, or you could also wear a hat. But I do know that pheomelanin does a lot of things that are surprising. So one of the things about pheomelanin is that it doesn't respond to light in the same protective way as eumelanin.

So eumelanin is photoprotective, which means that it's really good at taking that radiation and making sure that it doesn't damage your DNA. And basically just holding it down. So eumelanin comes in brown and black forms. And it's there dissipating up to 99% of the UVA and UVB radiation that you do absorb. So thank you, eumelanin. Now pheomelanin, which tends to be yellow and reddish, well, pheomelanin on the other hand is phototoxic.

And so what's really interesting is that they found that people with red hair who have a higher proportion of pheomelanin seem to be more prone to skin cancer in a way that doesn't just relate to you have less pigmentation. And another interesting fact is we don't just have melanin in our eyes, skin, and hair, these visible places. We also have neuromelanin. And I actually went down a rabbit hole because I'm like, I don't even study like neuromelanin like that.

And neuromelanin is made from eumelanin and pheomelanin. It goes through this process. You already have these precursors and you make this final form of like neuromelanin. And one of the things that they found is that neuromelanin is involved in a number of different things, but I started reading up about it in the context of Parkinson's. And I remember reading that people with red hair are more prone to having

Parkinson's or have like higher rates of Parkinson's, something like that, which is something that might have to do with the relative proportion of eumelanin to pheomelanin that they have and its ability. So the neuromelanin's ability to clean up whatever it's supposed to be cleaning up in the brain. So it's just super interesting that melanin does so many things. And that's just in humans. Like, and I'm trying to stay in my lane, but I would be remiss to not

mention that you have melanin in all kinds of organisms. Fungi as well. That's the thing that got me. I was like, Fungi have melanin? Fungi have melanin. Like you can extract melanin from plants and fungi, and especially like fungi are like a really efficient way of like getting more of them. And I remember reading about certain kinds of fungi that are in particularly

hot environments that have more melanin. It seems to be doing something to protect them from some thermal radiation. And in some cases, some fungi are thought to have evolved this melanin to actually absorb more solar radiation to heat up more quickly because they're in very cold environments. So just melanin is this beautiful multifunctional thing. And if you think about it, from like an evolutionary perspective, even though they're different forms of melanin, this structure

is so old that we share it with the last common ancestor that we have with fungi. That's nuts. That's nuts. That actually makes me wonder if you are closer to the equator and you have more skin pigment and your hair is darker, let's say, do you get hotter? This is like a fascinating question to me. And I also ask this as a, as a transparent goth girl who has no skin pigment, but wore all black all the time and was sweating.

But still, yes, it's so, it's so funny. As somebody who grew up as a, you know, a little teenage goth in the Netherlands, he was not so much an issue, but I really respect your dedication to gothdom in California. That's real. So this is really interesting to me. I love history and philosophy of science. One of the most fun things to me about science is the fact that it is done by scientists and scientists are subject to their own biases.

And when you think about skin color these days, I would say that in general, nobody questions that it is useful in a very high solar radiation environment to have darker skin. It's like, we're like, yeah, no, they seem to be doing good. I think that they've got the right trait for, for, for the job. However, back in the fifties, even, which is pretty recent, you can find articles where people are saying that it does not make sense that people have darker skin in places with more solar radiation, because darker objects heat up faster in the sun.

So there's no way that it's useful. They're like, there's no proven reason that it's useful at all. Like it's probably very maladaptive. And it's super funny because I like to think of those people as like in publishing probably some British journal. I'm like, you know that the second you went out to colonial, whatever, you were walking around looking like a lobster, but you said, no, those people seem like they're struggling.

That's fascinating to me. So this is a great question, right? Do we have the same issue with black materials as we do with darker skin? And it doesn't seem to be the case in part because the effect that it has, it doesn't seem to be distinct enough. It doesn't seem to be that you get that much more solar radiation on darker skin as you do on lighter skin, because lighter skin is not able to reflect as much. And it's probably because the radiation touches the surface of your skin.

So you're already in trouble. You can't necessarily reflect enough of it back for it not to affect you. That's different than necessarily wearing those colors, right? One of the things that people remarked is that various tribes that lived in the desert would wear very dark clothing and that there were also very dark haired goats in the Sahara. What it seems to be is that absorbing that radiation can be a good thing if it never reaches your skin.

But in general, like as far as people go, like it does not seem that if you are darker skinned, you significantly heat up more than lighter skinned individuals. And where in the dermis? That's a scientific term for skin. I don't know what I'm talking about. But where in the dermis or epidermis or quasi-dermis is our pigment? Great question. So it's in the epidermis.

And so the melanocytes live at the bottom at the base of the epidermis. And the way that they work is they have these tentacles, these dendrites that stick out into the epidermis and can deposit these melanosomes. So those little vesicles of melanin, the little melanin creating sacs into keratinocytes. So the keratin cells that are actually your skin. And in those keratin cells, as you are making more of them, basically you end up like pushing more up. So you make them at the base and then you slough off what's on the top.

And then just you have new and newer ones. And that's kind of how like exfoliation works. Like you take the top layer off and then it's like new cells underneath. Now, whether those melanosomes stay intact, doesn't seem to be clear. In some cases, I've seen people say that it basically is like melanin granules and dust that's like spread out. In some cases, it may stay more, you know, directly in the melanosome. But that's kind of where it lives.

At the very surface of your skin, basically. So your skin has the epidermis. That's a top layer. And then the dermis underneath that. And the dermis is kind of the hangout center for your hair roots and your sweat glands and other gooey things like that. But right before your surface epidermis turns into that deeper dermis, right at that border, there are those cells called the melanocytes.

And they look kind of like an upside down octopus with a bulbous end and kind of arm thingies reaching toward the surface of your skin. And in these melanocyte, octopus looking cells are organelles and they're called melanosomes and they make the melanin granules and then they shoot them out of the ends of the arm things into your keratinocytes. Just call them skin cells. And this whole shebang, it deserves a fancy word. And you know what?

It has one, melanogenesis. Look at your arm. Look at your arm. All that drama, just unfolding it every day. And then what about in your hair? In your hair. So that's, that's interesting. Like I think it's deposited in your hair shaft in a similar way.

We don't necessarily know exactly how that transfer of melanosomes happens in the hair. There's like some different ideas about options of how the melanosomes get transferred, but once it's there, it's in the keratin cells of your hair, which are different than the keratin cells in your skin. But the distribution of those melanosomes seems to be a little bit complicated because like an individual's hair shaft can be very different. Like you have individuals who have very thick hair shafts, you have individuals very thin hair shafts, you can have a medulla in the middle of your hair.

So like a hole or it might entirely be solid. And so if you look at microscope images of cross sections of hair, so like thin slices of hair shaft, you can see that there's differences in distribution. Some hairs have melanosomes that are just like clumpy distributions. Others are like a little bit more evenly distributed across the hair. There's just a lot of variation and all of that variation influences how dark it looks. So one of the things that I did in my undergrad actually is I worked with these really cool melanin chemists in Japan who had developed a way of chemically

measuring the amount of you melanin and pheomelanin that existed in the hair, which is really is just so cool. So they took all kinds of hair samples that I had and measured exactly how much you melanin and pheomelanin was in them. And one of the surprising things that I found was something that went against my expectations, looking at African and African descendant individuals and their hair and different people of Asian ancestry in my hair. So I had expected, well, the Asian hairs that I've seen,

whether they were South Asian or East Asian, they're black, they're jet black. That's a thing that I think a lot of us are familiar with. It's like jet black hair, Asian hair, you know, that's a thing and it's awesome. So naturally you would think there must be more melanin in that than maybe some of these African hairs or people who are from the African diaspora because like you hold them up to the light and you kind of see through it. It's kind of brown. However, I found that that wasn't necessarily the case.

Most East Asian hairs, most Asian hairs in general had less melanin. And so that made you think about what makes something look dark. Well, if you have a thicker hair shaft, then you're going to have more trouble passing light through it, right? So you might need less melanin to make it look completely black as opposed to if you have a little bit of a flat hair shaft and it's a little bit of a thin hair, like it's like thin paper. It doesn't matter how dark the paper is, you can pass more light through it, right?

And again, this was Dr. Lucissi's undergrad work and it was published in her 2016 American Journal of Physical Anthropology paper, Quantifying Variation in Human Scalp Hair Fiber Shape and Pigmentation. And there was a correlation with skin color. So that was also something that was a little bit surprising. Within individuals who had dark hair, it seemed that individuals who had darker skin also seemed to produce more melanin everywhere.

So in my sample, like I'll never forget, the individual that had the most melanin in their hair was a South Asian person that also had the darkest skin in my hair sample. And that was such a cool example of pliotropy and the way that. So that has to do with genes that affect multiple traits. So you can have something like genes that affect melanin in some places in your body. And then you can have genes that affect the entire production of melanin throughout your body. And one of the things you can think about is like blue eyes. A lot of individuals have like lighter eyes, but you know, could also have darker hair.

It doesn't necessarily have to go together. So there's a mechanism that we have by which we can kind of tinker with some aspects of our physical traits without tinkering with others. Yet a lot of times what's really interesting is figuring out how some traits might be connected with each other because you have the same genome in every cell in your body pretty much other than your gametes. So it's always a question of how are we using that genome to make different things? Are we using it in different ways?

Are we using it in similar ways? Are there different pathways? All kinds of stuff. So all those locks of hair that you've been saving in a shoebox under your sink, you can science those. Getting back to those samples, were you able to tell that person like congratulations? I have 3400 samples and yours is special. Or where are you? Are you getting those from salons? Are you getting them from people who volunteer a hair or two?

Exactly. It's really that. So, OK, it's so funny because like I've literally been doing this for like 10 years. I'm like, I can't believe I can say I've been doing anything for 10 years, a third of my life. I think about that a lot. So I'm talking about research that I did when I was in undergrad. So when I was, you know, cute little undergrad, I was like, I want to do a science. I basically said I want to learn about pigmentation in hair and I want to learn about hair morphology. And so I need to get hair samples from people as a wee baby undergrad.

I did not have resources, infrastructure or money, but I had a lot of pizzazz. I had a lot of energy. So what I did is I started with people that were around me and I was like, hey, I'm doing the study, can you give me your hair for this study? And I'm also going to measure your skin color. And surprisingly, like, you know, a lot of people did were some of them my friends. Yes, but it's all good. I had like ethical approval to do the study, but then I also went to salons.

So I it was especially important to me to get representation of people of African origin and people who are afrodescendant. And so at the time I was living in Cambridge in England, which isn't the most diverse place on earth, not from what I've heard, shocking, but London was very close by. So like I went to London and I like explained to people, hey, this is what my research is about. I went to some barber shops and I was like, hey, you're already getting your haircut. This is what my research is about. Can I have some of your hair?

And in the end, I had like a little bit under a hundred hairs and I did all my little analyses at some point I did know who was who. And especially people who were my friends. I'm like, this is their hair. And for one of my friends, I was like, girl, you have the straight, literally quantitatively the straightest hair in my entire sample. Congratulations. That's exactly.

So for that person, I was like, yes. To be a superlative at anything is exciting. You have achieved something in my sample. But when I went to Penn State, which is where I did my PhD, I was working with hair samples that were drawn from a larger study of like 4,000 people, more than 4,000 people where not only did I not know who those individuals were, like I'm not supposed to know, right? That privacy, very, very important thing.

And so I wasn't able to report back anything like that unless they were part of a later addition to the study that I did, which is about red hair. So I did my master's paper during grad school on red hair. And we basically got permission to recontact all the red heads, all the people who reported they had red hair. And I was like, can I get some more hair, please? And then I measured, like I worked together with those Japanese scientists that I had worked with as an undergrad, Ito and Wakomatsu.

And they reanalyzed those new hair samples for me. And I also took photos under the microscope of those individuals' hair. And so as part of that study, basically one of the incentives was, hey, please give me your hair and I will tell you about your hair. And so that's something that I really enjoy. And, you know, as I'm thinking about future research that I'm doing and when I'm going to be working with people again, that is the kind of information I want to share back because I think it's so cool to be able to learn about yourself.

And one of the things I want to offer people is, OK, if we're going to take your hair sample, analyze it, I want to give you a result where you can see relative to other people, like where your hair falls. Like it tells you a little bit something about like, hey, compared to the, you know, rest of humanity, what are you like? Yeah. And as a fake redhead, is there like a shade on the market that's the closest to real redheads? Because mine is always a little too purple.

Interesting. And if you leave it on a little too long, it gets more purple. It depends. Sometimes it works out. Sometimes it doesn't. Is there like a shade? Well, answer that. And then also maybe this is kind of around the same thing.

But when you are having to kind of quantify or people's different skin tones, is there like a Pantone wheel that you without? I love answering these questions. So I will, I will tell you, like, how do we measure people's skin color? So first, I have no idea because I've not done any market research on like the colors that exist out there. It would. There's two reasons why that question is difficult to answer.

The main reason is there are so many different shades of red hair because from that research that I did for my masters, you could have red hair in all kinds of ways. Like you could have red hair where you had a lot of feel melanin and a lot of you melanin. And so it was very dark and very red. But there are some people who had not so much you melanin, but a lot of feel melanin.

And so it was like much more orange looking. So there are so many different shades of red hair that it would be difficult just on that basis alone to be like, okay, this shade is like the most realistic that said there are going to be more plausible colors of red and things where you're like, unless you are some alien life form that has developed a new shade of melanin that is purple, this seems unlikely, but I could not give any good advice. However, that said, it would be a fun study to do and be like, okay, who's

the real redhead here? Yes. Oh, fun game. I mean, I literally have like Googled a picture of a baby orangutan to be like this. That's right. Right here. I would like that.

I'm giving orangutans or greys orangutans managed to be a fun color. Do orangutans. Do they have feel melaton melanin? It is feel melaton that makes their hair orange because we know that that is the only pathway we have in mammals, I want to say, to get that red color. I say in mammals because birds can have red feathers. And what makes red feathers is actually not feel melaton. A lot of times it's a type of keratin.

For more on feathers. Yes, we have a whole plumology episode, which I will link in the show notes. You are welcome. And then their blue is like an absence of pigment sometimes, right? Yes, it's a structural color, just like our eyes. And this is like another fun fact that I like to whip out at parties. I'm so much fun at parties. Invite me y'all.

I'm like, did you know that there's no blue pigment in blue eyes? It's a structural color. So if you align collagen in a particular orientation, the way that the light hits it makes it look blue, just like there's no blue pigment in the sky. But it's, is it the Tindall or Raleigh scattering? One of the two. No, I think it's, I think it's Raleigh, but I'm not sure. Yes.

I think it's, or is it Raleigh? It's a really scattering in the sky and then a Tindall, a Tindall scattering in the eyes. Now, the difference between those two has to do with like the size of the particles that is reflecting the light, ask a physicist. So of course, Dr. Lucissi was right. And as we covered in the ophthalmology episode on eyeballs, the physics of the blue sky is called Raleigh scattering.

And that has something to do with the size of the particulates. But in the eye, in the iris, it's called the Tindall effect. So in blue eyed peepers, that lack of pigment lets the shorter wavelengths in blue light scatter and reflect back like little freaky translucent bounce boards. It's boggling, perhaps, but not as boggling as the cultural discussion ignited by a 2016 episode of the FX drama. You're the worst. You don't wash your legs.

No way. What am I, a sucker? Well, you take showers and you don't wash your legs. What am I going to do? Like bend down and wash my legs? Who has the time? Which continued to cause some really heated debates on Twitter in May of 2019, before Twitter became like a place to exchange emergency pandemic information.

And then before everyone scattered to mastodon and Twitter became like an abandoned mall. I don't know if anyone asked about this, but as I'm pulling this up, you know, the Twitter discussion about how white people don't exfoliate enough and they don't wash their legs. Are you familiar with this? Yes. Yes, I'm familiar. Which, by the way, washcloth all the way.

Yes. Washcloths. We love washcloths. Love them. But is there something about not having a lot of skin pigment where you don't realize how much you've, you're like, how actually you are? And I'm wondering if there's some sort of biological anthropological reason why so many white people are like, I have to wash my legs?

I don't understand. Anyway. So two things. One, at some point, we should circle back to me answering how you measure skin color because I never answered that. Oh my gosh. Yes. Thank you.

And to answer that question, so basically put another way. Is ashiness just not visible on lightly pigmented individuals? Yeah. That could be a significant factor. So I imagine you have like dryness and when our skin flakes off and dries, like it's these thin layers that end up reflecting more light. And so they look lighter than the rest of your skin, especially if you have darker skin.

So that, that ashiness is then, you know, probably more evident. I'm not saying this definitively because I don't even know if anyone has ever studied it. It's like, you know, can you just not see that lightly pigmented individuals are very ashy? I think that it's mostly a question of culture and like, you know, whether something is important or not important. However, the interesting thing about like human variation is we think about like,

you know, light and dark, but we also talk about like white people. There are lightly pigmented individuals who are not white Europeans, right? And darkly pigmented individuals who are not black or of African descent. And so the question would be, are there any other variables that influence how your skin retains moisture that are differently distributed around the world? Because it could also be that maybe there are some aspects unrelated to pigmentation at all, where people of African ancestry actually have skin that loses moisture more quickly.

And therefore, you know, moisturizing is more important. Now, when it comes to exfoliating, there's just like so many exfoliating and washing and bidets. You, I really wouldn't want to rob anyone of the opportunity of going through Twitter and just experiencing firsthand the observations and discussions that exist there. But I can tell you that from the perspective of anthropology, there is not a body of literature that covers that.

Perhaps, perhaps in the future. Perhaps in the future, we shall see. But for now, we have some really great articles and op-eds on the matter, like the 2019 piece written by Nicole Hernandez-Royo, who noted that, quote, not washing your legs or not taking a shower every day is not class rebellion, but a display of which bodies are allowed to be unwashed without stigma attached. Being understood as dirty or clean can be the line between violence and survival for minorities, Nicole writes.

And in a March 2021 Vogue article titled, More Than Just Dry Skin, The Cultural Significance of Ashiness, Black Journalist and Editor Andrea Platt writes, quote, Ashiness at its core colloquially means dry skin, which along with having red blood is a trait much of humanity shares at some point in our lives. On skin tones that are darker than a phenotypically pale-skinned white person, the higher contrast of the grayish white patches and the surrounding areas makes the condition more visible, Andrea writes. However, Andrea continues, in that alchemy of black social struggle,

black personal grooming and black linguistic cool, it has metastasized from the dermatological to the cultural and political. Ashy signifies not only a dry epidermis, but also a careless lack of self upkeep and communal neglect. Platt concludes, the battle against Ashiness also reflects black people's ingenuity under white supremacists withering dehumanization. And you did mention, you know, as a biological anthropologist, when it comes to even 10 or 15 years ago, I feel like in America, someone would say, oh,

this African-American man, and we don't say that anymore because it's not always representative of what their heritage is. But when it comes to someone who studies pigment and the difference between the way that people use labels in ways that are helpful and not helpful, do you see a direction that that's going that's just more respectful of people's backgrounds, but also not so categorical? I think about this so much, I would say that, like, like most of the time, what I think about is how we conceptualize

and measure and discuss human variation. What is the most appropriate way to do it? So the example that you gave, like, let's let's go from there and unpack it. So I have had people refer to me as African-American because they do not want to say black and so like, oh, well, to say African-American is the PC way to say that somebody is black. And historically, in some cases, like people have claimed that. So I'm like, I understand that.

However, by a lot of definitions, what people mean when they say African-American is someone whose ancestors have been in the US for a number of generations and are descended of people who were enslaved. I'm a not even a first generation person. I just came like what, how many like eight years ago, seven years ago to the US. So I'm not part of that population. So there's a lot of reasons why that's an issue beyond just thinking about respect. If you're thinking about scientific studies that we want to do, especially

medical studies, where we think like, hey, this group of people who have a lot of shared ancestors might have a lot of shared genetic variation that's associated with, you know, some condition or some trait. You don't want to assume that someone who is does not share any ancestors with them at all just because they look similar is in the same group. You don't want to include those people in the same category. So for example, I experienced that a lot in medical settings where there is a so-called African-American correction.

So kidney. Yes, GR at the. Yeah. So this is EGFR or estimated glomular filtration rate. And we covered in the nephrology episode that EGFR is a measure of how well your kidneys clean pee and water out of your blood. And we also talked about how there's something called a race-based coefficient. And that's based on the assumption that black patients have higher muscle mass.

What does this mean for black patients? It means delays in seeing specialists, less access to kidney transplants and, of course, worse health outcomes. So after petitions were started by med students, Mount Sinai announced in 2020 that they switched to the more accurate chronic kidney disease epidemiology collaboration equation to calculate that EGFR. And they eliminated the race-based coefficient. And if you're not black, you may not have even been aware this existed.

There's a lot of like there's there's a number of different metrics in blood work where I've seen that. And I'm like, huh, like they gave me an African-American correction, which is confusing for a lot of reasons. And also because I have one European parent and one African parent. So I'm like, how like, what's your logic behind that? Like, what do you assume is the reason that you need to make that correction? So this is just the question of like labels and the fact that, you know,

African-American confounds a lot of different things. But in general, what you also want to think about is what you are describing. I have seen people avoid talking about race by talking about skin color instead. They're like, oh, people with like darker skin. And I'm like, do you mean people with darker skin or do you mean black people? Because there are black people who have very light skin and might, for example, have issues with, let's say, facial recognition. That's a huge thing these days.

So there's a lot of facial recognition. Like it literally our phones, me and my iPhone that can't recognize my face half the time require training data sets that represent a range of human variation. And when we're making those data sets, it's important that we are cognizant of different traits that vary in people and that we make sure that those traits are represented so that a system is trained to distinguish individuals that are variable on all of those axes. Now, if you say, OK, we need to make sure we have a lot of people

who have dark skin in there, there's going to be other facial variables that aren't taken into account for that. So you could have a whole group of dark skin individuals and not a single person of African ancestry, because you could have everyone be South Asian. You could have everybody be Native American from, you know, the Amazon and have very dark skin, no African ancestry necessarily. And on the other hand, you could have individuals who are pretty light skin, have African ancestry and have features that is shared with other people

who have African ancestry, doesn't have anything to do with skin color. And so one of the things that I found is that there's this hesitancy to talk about human variation. In general, my entire platform is human variation is not a bad thing. That is what I want to educate people about. And like as a professor, that's what I'm going to be lecturing about. I want to empower people to think about human differences as a neutral and maybe even positive, fascinating thing.

Instead of necessarily thinking we need to say that all humans are the same because if we say that there are differences, that's necessarily going to lead to bad things. However, bad things only happen when you rank differences. When you say some types of people are better than other types of people, which is not even a scientifically valid question. That's a subjective, qualitative opinion, theoretically, that you could argue in a philosophical context, but not in a scientific context.

So one of the things that we need to think about is how we talk about that variation. How do we want to think about these things? There's a lot of different ways and one of the more common ways to refer to these differences these days is ancestry, like so this concept of ancestry. Now, the difference between ancestry and race and ethnicity can be complicated. But in general, if I wanted to quickly define it, what I would say is ancestry can be a useful way of thinking about things. If you're thinking specifically about ancestors, do you have more shared ancestors?

Do you have fewer shared ancestors? And one way of thinking about that is, you know, talking about different geographical regions, but you have to be careful about that. Like you can have people who have African ancestry and are very distantly related because their African ancestors could be from different parts of Africa, haven't had a shared ancestor for a very long time. They could be more genetically different from each other than somebody from Western Europe and somebody from Central Asia.

So we have to think about ancestry in this dynamic way that is continuous. Like we don't have different subspecies of humans. We don't have different types of humans because humans are a relatively new species that has like exploded all over the world and has interacted and intermingled in all kinds of ways. And let's not even bring in Neanderthals. I'm not going to bring in Neanderthals. I'm tempted to bring in Neanderthals.

They're on my mind. They're always on my mind. Just a quick side note, we didn't even know Neanderthals, aka Homo Neanderthalensis, existed until the mid 1800s. But just to give it a little bit of context, humans discovered dinosaurs in 1824. No one knew there were dinosaurs before the early 1800s. What? So of course, we didn't know that there was another species of humanoid.

That was our Western Asia roommate for 40,000 years. So sure, yes, we boned 55,000 years ago, but species lines, they're kind of blurry. And that's why I'm married to a man with a prominent brow ridge who loves equipment of all kinds and can boast having more Neanderthal DNA than 95% of other 23andMe customers. But enough about our pasts. And I mean, do you think this is something when it comes to what you'll be studying and lecturing on in the future, like how do you decide which direction to

go when there's so much that has yet to be explored and really looked at and written on so many Wikipedia entries that don't exist yet? Bro, I don't even know what I'm doing next week. I struggle to prioritize what I need to do in the day. So like, it's a great question. I wish I had an answer for me, honestly, I wish I had an answer for myself. But in general, like the directions that I want to go and research wise is to continue to answer questions about hair.

So that was like my first love and I want to continue because I still don't have the answers that I want about what is the genetic basis of hair morphology. And with that, I want to answer, like, why do we have differences in scalp hair around the world? How did those evolve? Was natural selection involved? Was it just like random chance? And I want to go even further back and answer the question of why do humans

have scalp hair with naked bodies? Weirdos. It's a great question. I love it, but I want to understand it. Why? What was, what was the reason? What was the reason? And also soap dispensers that work with people who are white. Yep.

Have you seen those videos? I have seen those videos. Yep. Yeah. How does that happen? And actually that circles us really nicely back to how do you measure skin color? Oh, right. So why do soap dispensers not work?

And what does that have to do with how you measure skin color? So a way of measuring skin color that we use is using this device called a reflectant spectrophotometer. Reflectant spectrophotometer. So what those devices do, there's different kinds, but the ones I use, it shines light on your skin and then measures what is reflected back. And color is really about what areas of the visible light spectrum are being reflected versus which ones are being absorbed and how much light is being

reflected versus how much is being absorbed. And there are different parts of the visible light spectrum that can tell you things about different color components, including melanin. So there's this thing that we can calculate called melanin index from that information. So melanin index is a metric of how melanated your skin is relatively. And it goes from like the lowest numbers I've seen is like 20 something to over 120.

And that is a way of objectively measuring skin color. We don't have to do Pantone, like, you know, matching and all that kind of stuff. Now, what's interesting is that that also has to do with why these soap dispensers don't necessarily work because they also use light. And I'm pretty sure I think they use red light. We have similar issues with pulse oximeters where they're not able to measure oxygen content accurately in people with darker skin because they are calibrated to assume that, OK, well, if this is the information you're

getting back, this is the light that's being absorbed or reflected. This is what that means. But when you're doing something that affects light, reflection and absorption, you need to correct for various things like melanin that absorb light. And that is what's really not being done in a lot of those settings, because sometimes people assume like, oh, if it works in these individuals, it must work for everyone. And again, that is why I got my little soap box.

And I'm like, it's important to teach people about like human variation because there are things like this where, surprise, human variation is actually going to influence whether this works for everyone. It is not just like a basic principle of like it works or it doesn't. It's who does it work for and what different features in humans might affect how this works. And when you're using the machine that gives you a number, 20 between 120. Reflecting spectrophotometer. Do you have to do that on like their untanned butt?

Where do you do that? So I've had discussions with one of my former advisors about that. And yes, like somewhere where the light never touches with the ideal in some ways. We found a nice compromise using the inner part of your arm. So yeah, the inside part of your upper arm is like relatively a place that receives like less, what would you call it? Like less radiation is less likely to be tanned. However, sometimes we actually want to measure that.

So I have data from some studies where we measure people's foreheads and that in order to ask a question of like, oh, how tan is that individual? Like how much melanin could they make under, you know, the solar radiation that they've been exposed to? So there's that. And actually one of my advisors has done a study where basically they measured. I want to say the top part of people's butts and like, you know, how light or like how melanated it was, but also how red it was.

And then they basically exposed them to like, you know, a little bit of radiation there and like, I don't give them sunburns on their butt. And we're like, how sunburn did you get and how long did it take for that sunburn to go away? Which just like they're really fun science experiments out there that people have done. You're like, oh, I'm helping some researchers. I'm helping some. I am showing them my butt cheeks.

Can I ask you questions from listeners? Oh, absolutely. We have so many. We'll go through as many as we can. We're going to lightning round. You ready for this? Yes. But before we dive in, let's toss the money toward the cause of her choosing,

which is the fieldwork initiative, which seeks to maintain a network for victims who have struggled with gendered violence while conducting research. And it also promotes pre-fieldwork training seminars that shed light on the realities of trauma and racism and gendered violence in fieldwork. So shout out to their founder, Jerica Heinz, who Tina says is a wonderful human being. So you can find out more at fieldworkinitiative.org. And thank you sponsors of oligies for making that donation possible. All right, your questions, patrons, including first time question

asker, Eleonora Lux and Sarah Ayala. OK, several people among them, Anne Hanlon and some other people want to know, why does the sun make your skin darker, but your hair lighter? Ooh, that's a great question. Right. Oh, that is such a great question. OK, so the reason sunlight makes a lot of people's skin darker is because it stimulates melanocytes in your skin that is alive, important,

to make more melanin. And so that is a physiological response that is activated by sunlight. And when it comes to your hair, your hair is dead. So any melanin that is in your hair that gets destroyed can't be replaced. So if you have already like relatively little melanin in your hair, your hair can undergo what is called photobleaching, which really just means the pigment was destroyed by light. And it's not there anymore.

So your hair is like lighter now. Plenty of you. Lyti, Shreya Allahi, Manas Viverma, Janetta Soar, Min 09, Becky Grady, Trevor Doty, all had SPF questions. And Laurie B asked, can we please once and for all have the final answer about black folks in sunscreen? Yes. No. Sometimes. Bryn wants to know, how did humans figure out how sunscreen works?

Like, and did humans use substances found in nature's sunscreen? Also, feel free to lecture us about sunscreen right now. Open forum if need be. Great question. So first, when and how did humans discover that you can protect your skin from the sun? Unclear. But there are some groups in East Africa. I want to say Tanzania, who use red ochre on their skin.

But it's basically like this red like sand clay pigment that they can put on their hair and their skin that protects their skin from the sun. So like, even if you have dark skin, you can benefit from reducing the amount of radiation that you're exposed to. You can just benefit from it because like, why put your skin through it? Why put your melanin through it? If you don't have to, especially if there's already enough solar radiation for you to get the vitamin D that you need.

We have evidence of humans playing around with ochre. I want to say 200,000 years ago. That's a number that seems like I remember, I think, where we have engraved pieces of ochre. And so it's possible like humans started playing around with that, put it on them and we're like, hey, this does something, but we can't really know for sure about when they started using it. But yes, correct. According to the paper, assessing the photo protective effects of red ochre on human skin

by in vitro laboratory experiments, red ochre, or hematite, which is a deeper red variety of iron oxide, has been used in Africa since the Middle Stone Ages, some 280,000 years ago. And it has a sun protection factor or an SPF up to 13. And you're like, what does that number mean? Well, the SPF number means that fraction of the burning radiation will reach the skin. But most sunscreens only block UVB rays. And we know UVA can also cause damage to skin and cancer.

So look for a broad spectrum SPF and look into mineral sunscreens, especially if you want to spare negative effects on ecology, like coral reefs. You can see the Naderialogy episode on corals with Dr. Shale Matsuda for more on that. A great question. Heidi Stushnov says, black, white mixed person here. I and a few other mixed people I know tend to go blotchy when we tan. What's up with that? Interesting, blotchy.

Hmm. So I assume that that means you get an uneven tan. And I'm going to assume that you're mostly noticing it in your face. I don't know why I'm making these assumptions. I'm acting like I'm a psychic. So actually, as a fellow mixed person that has one white parent and one black parent, I would say that I don't go blotchy. But what's really interesting about humans is that, especially when you get mixed humans,

so people who have parents who are from populations that don't have shared ancestors for a very long time, you could get whatever the fuck in that mix. I like to call myself an F1 hybrid. Don't ever call anyone an F1 hybrid. You can call yourself an F1 hybrid if you want. That's what I do. You never know what you're going to get in that first generation. You can get a lot when you mix genes that haven't been mixed together in a long time.

So my intuition would be if you are going blotchy, you maybe mean you're getting freckles because that can be something that we perceive as that. Another form of blotchiness that people talk about is melasma or a pregnancy mask. So during pregnancy and other moments where your hormones are doing things, it's possible to basically get an even patchy distribution of darker pigmentation on your skin. So that might be a hormonal thing as well. I am not the kind of doctor that diagnoses people with anything. So if it is an issue, definitely talk to people.

But my intuition would be to ask, you sure you don't have freckles? And then it's you, could you be pregnant? I don't know. Interesting questions. Perhaps follow up on their part. Indeed, a bunch of folks. Looking at you, patrons Kendall M, Erin Ryan, Zambot, Cynthia B, Lauren Cyberg, Kayla C, Alexandra Coutul, Biro Tavares, Brittany Corgan, Michael Roy, Josh Frye, Shannon Bushnell,

and Samantha Reyes, who asked, why has my melanin ghosted me? All of you. Wanted to know about the condition of vitiligo, which from what I understand, autoimmune? Yeah, I'm not a medical person, so I don't focus very much on that. But from what I know, vitiligo, autoimmune condition that destroys melanocytes. So with a lot of different autoimmune conditions, basically, you're self-destructing things that you don't need to be self-destructing, and that is one of those examples. So that's what's happening there as far as I know, as to why I wouldn't know that.

So patrons Jules and Jennifer Huisman also asked this, and vitiligo can occur in up to 2% of the population. So it's pretty frequent, if you ask me. And it happens when your T cells go bully your melanocytes, and then areas of skin wind up with less pigmentation. And right now, there isn't a cure for this, but there's laser therapy, which can help, and corticosteroids can also benefit some folks, as can phototherapy, with that shorter, but more intense form of light, the UVB rays.

So you can look into that, but also, it's gorgeous. I think it's gorgeous. So there's your internet dad's 2 cents, and I have good taste. Now this next question was asked by patrons, Beth Kennedy, Scott Sheldon, and first-time question asker, Mary Ann Thomas, and it's a real chinscratcher. I thought this was a great question. Nina Chakobi wants to know, why do some people have brown scalp hair but red beards? Oh, that's such a great question.

What's up with that? That's one of my favorite things. I was going to say I'm a criminal. I'm not a criminal. Please do not arrest me. This is not a confession. Hounds to ever. I am a weird person.

People who have beards, I'm like, I saw that you have some red hairs in your beard. I'm really interested. Do you want to talk about that some more? You have a PhD in this. Yeah, exactly. It's like, this isn't weird. It's for science. Yeah.

It's okay. That's how I justify. I'm always like, this isn't weird because I study this. So we don't know the exact reason why, but we can infer that hormones have something to do with it. So beards are a great example of a secondary sexual characteristic. So sex is a whole dimension of variation that you can have in people that we can most clearly see within an individual as they age because you go through puberty and things happen and

you can go through other things in your life where your hormones are doing things. And when it comes to beards, you know that those come through during puberty when you're having an increase in certain kinds of hormones and there's going to be an interaction with the hormone receptors and their distributions in certain places. And so what we can infer is that it's probably interacting with melanocytes in some kind of way. And there is melanocytes stimulating hormones. So hormones aren't just like, you know, sex hormones, they're all kinds of hormones that

are giving each other signals and basically affect how different traits are expressed. So this is totally just like a random tangent where I'm giving you more questions. You don't understand how, but basically hormones probably are doing something. Oh, Katie Munoz wants to know, I heard that blonde-haired blue-eyed people inherit their coloring from Neanderthals. Is this true? Oh, that's a very interesting question. To my knowledge, that is not the case.

Too simple. That's too simple, right? It's always too simple. It can never be simple. It has to be complicated. So absolutely, we think that there's probably some genetic variation associated with skin and pigmentation that was contributed to some populations by Neanderthals. We don't necessarily think that blue eyes and blonde hair are a gift from Neanderthals.

You may have also heard something about Neanderthals having red hair. So that is actually based on a study that got a lot of things wrong and we do not have any evidence that Neanderthals necessarily had red hair, nor do we know much about what they would have looked like necessarily because they have some types of genetic variation that aren't present in modern people. So they fucked that one up a bit. A little bit. A little bit.

A little bit. Graying hair. Katie Stomps wants to know, why do some people go gray white earlier than others? Their hair has significant white and they're in their late 20s. My grandmother was a real Steve Martin and she went white early, but she also had 11 children. Wow. By like 30.

Ah. Catholic on a farm. What are you going to do in my life? This person has, I have one dog. I know. She would, she evolutionarily, one, very successful, very successful, you, she understood the assignment. She got it.

She understood the assignment. So yes, Grandma Ward, she was a real one, 11 kids by 30. And I have more cousins than I can literally count. I don't know how many cousins I have. We wanted to add manic panic to my grandma's hair so bad, but she had access to farm equipment that could kill us. But anyway, patrons, Katie Stomps, Delaney, Frederick A. Schweigart, Catherine Wood, Abby Sacks, Naomi James, I Has Questions, Pachicha, Rogue Dookie, Jenna Congan, Nina Evesie, Trevor

Durning, Earl of Grammlekin, Jess LaFleur, Lacey, Pavka, 34, Rachel Kasha, and First Time Questions, Chris Jen Crawford, and LB, all asked about silver streaks and death's icy grip. But gray hair, Tim Fleur wants to know, can gray hair ever regain its original coloring or are we just screwed once it loses its color? So yeah, is it that the stem cells or the melanocytes are just like, I'm out? I'm out. Yeah.

Interesting, right? Because we see that happen with hair, but we don't have evidence of in-age, a kind of senescence or aging where skin melanocytes are just like, I'm completely out. There is some evidence that, you know, in some people there's decreased melanocyte activity in their skin as they age, but nothing like hair where it's just like, I'm out. Also, I would like to state that I do not have a single gray hair to demonstrate the amount of hardship that I went through in my PhD, so I am very, very jealous of anyone who does have it, and I will sometimes fake it by braiding my hair with like, you know,

gray hair and being like, no, I am learned and wise. You're professorial. I'm professorial. At the temple. At the temple. Exactly. Boom. So yes, gray hair has a little bit of eumelanin, the black kind, and appears silvery because

that's all of the pigment it has, but brown eumelanin without other pigments gives someone blonde hair. A little bit of brown eumelanin and some pheomelanin, that's a recipe for ginger hair. But back to gray hair, that loss of pigment as you age or maybe if you're under a lot of stress. So I looked this up and there was a July 2021 cell biology paper titled Quantitative Mapping of Human Hair Graying and Reversal in Relation to Life Stress, and it noted that aligning the hair pigmentation patterns with recent reports of stress in the hair donor's lives

showed striking associations. And when one donor reported an increase in stress, a hair lost its pigment. When the donor reported a reduction in stress, the same hair regained its pigment. Furthermore, it continued, white hairs contained more proteins linked to mitochondria and energy use, which suggests that metabolism in mitochondria may play a role in hair graying. I don't know what this means for your hair or for my hair. Maybe it's all stress. Let's just, let's take our phones, let's agree to throw them in a hole, and then let's

just go live in hammocks. Speaking of aging, Susie Krueger wants to know their friends who are all in the cusp of 40 were talking when one asked what lotions were used for aging. So essentially, does more melanin prevent you from aging so quickly, or does it prevent the appearance of aging? Yes. So this is one of the things that I find useful to talk about, and also when I'm trying to convince darker-skinned people or people who are from populations where a lot of people

are dark-skinned to use sunscreen, radiation damage, like UV radiation is not just going to give you sunburns. It's not just going to give you cancer, but it just damages things. It is a damaging thing. It can damage collagen in your skin. And collagen is one of the things that gives your skin structure and makes it taut. It is one of the targets of a lot of cosmetic treatment to make you look young and have your skin be plumping, all that kind of stuff.

So long story short, if you have more melanin, the damage that you are being protected from is not just folate damage, DNA damage, it's also damage to your collagen. So that is why dermatologists are so ... If there is one thing that dermatologists all seem to agree on is just a wear sunscreen, I don't know what they traumatize them with in dermatology school, but the fear in their eyes is just like, wear sunscreen. Photos of cancer. That's what they do. You know what?

You were right. Photos of blistering tumors, which is like, as a person who has gotten some nasty sunburns in my life, I pretty consistently have worn sunscreen every single day since high school. And there's maybe a handful of times that I have left the house and been like, I forgot it today. And it's like I've panicked. It's like I left a child in the house or something. And I did look this up and I found some articles that pointed to good sunscreens that don't

leave behind chalkiness, such as Fenty, KK Skin, Universal Mineral Face Lotion, SPF 55, Water Goop has a matte sunscreen, SPF 40, Black Girl Sunscreen, and L2ND is rated highly for clear sunscreens. And yeah, there are two kinds of sunscreen. There's physical sunscreen, which has minerals like titanium oxide and zinc oxide that just straight up block the rays. And then there are chemical sunscreens, which absorb the UV rays and they convert them to heat energy, which is bonkers.

So as Dr. Fliptoneta recommended in the Skotohyelology episode, do your homework and wear sunscreen. If I could offer you only one tip for the future, sunscreen would be it. But onward to kind of more important matters. Trevor Doty wants to know, what's the gene that makes me fairly fur-free above the waist and elbows? And then it's fur town from there down to my fingers and toes. How come some people have furry butts and others don't? That is a great question.

And again, it's one of those things where I'm like hormones. There's multiple factors that are going to affect any trait. But when it comes to the distribution of hair, a lot of times there are certain types of hairiness that occur like, you know, after puberty. And so you can say like, okay, there seems to be something that was activated after puberty that wasn't the case. Like, you know, you look at babies and they're relatively fur-less and they smell so good and they're so soft.

Anyway, that's a tangent. That's separate. It's not an evolutionary question. They're just delicious sometimes. But at some point, like there seems to be an interaction with various parts of the body that are influenced to have a different distribution of hormone receptors probably. One of the ways that you can see this is also like in pigmentation. So like our groins are actually much darker than other body parts.

And it's not because there's more sun exposure, right? But it's one of those areas in your body where you can be like, oh yeah, hormones doing something. This might make me do an aside on butthole bleaching. We'll see. It's true. You can buy creams, but some of them might be carcinogenic and there's another one made of mercury, so don't do that. But a doctor can also point a laser at your butthole and try to lighten it if you're worried

about skin pigment uniformity down there. You do you. It taint my business. I went to Thailand and I was so surprised in the drug stores in Thailand how many bleaching creams there were, which we don't see here in the US as much. Hydroquinone is something that I hear about a lot and I think that might be one of the substances that is actually allowed here. I think there are a number of different substances that you can use to destroy melanin basically,

but they can be very dangerous unsurprisingly. And so there are regulations that prevent them from being available in the US and in a lot of Europe, but there are other countries where you can get them and there's all of this pressure certainly contributed by colonialism to have lighter skin. So yeah, skin bleaching is like a huge issue in a lot of parts of the world. It was funny to me that there's so many tanning creams on our shelves and then there was so many and I was like, wow, this is just a gag. Yeah, it's all so arbitrary and it's all so lucrative.

I mean, it's actually much more like sinister than that in my opinion. Beauty has to do with what is unattainable to some extent. We value things that are hard to get. And so in a lot of historical cases, you can see this and around the world, it's like what the elite has is difficult to get and if it's easy to get, then it's not elite anymore and it's not special and therefore it's not beautiful. So what is beautiful isn't objective, but it has to do with people of high status having it.

And at one point that was food and extra adipose tissue that meant you didn't starve. And then at one point it was the time to have a trainer and at one point maybe it was staying indoors and not getting a tan because you weren't laboring. And then at some point it was being able to go on vacation and get a tan year round. And yeah, it's just, what can we get you to spend your money on? How can we get you to hate yourself? How can we get you to hate yourself? Just to spend your money.

See the Callology episode about beauty standards for more on this just infuriating nonsense. Anything else? A terrible, difficult, other than being a science communicator while you're also doing your postdoc and you're getting ready to have your own lab and everything. What's the hardest part about your job? Other than all those things, I feel like, no, those are probably the difficult things. I think the most difficult thing for me is picking one thing to focus on really because there's so many interesting questions to pursue and there's so many ways to try and

answer those questions. There are just not enough hours in the day. There's not enough hours in the day for me to do all the reading that I want to do, to do all the experiments that I want to do, to learn all the analyses that I want to do, to collaborate with as many collaborators as I want to collaborate. There's just not enough time for all the things that I have to do, which hopefully is going to be alleviated a little bit by moving on from being a one-woman show. Starting next fall, I'm going to be assistant professor of anthropology at the University

of Michigan. I'm going to have grad students and a postdoc, at least one postdoc. If anybody's interested in the evolution and genetics of human pigmentation, hair morphology, and skin pigmentation, facial morphology, hit me up. I'm going to have my own lab, so hopefully having more people on the team and working together on answering questions is going to make that easier because the more the merrier. That's so exciting. If you need to burn my butt, let me know.

For science. For science. For science. I'm so there. What about your favorite part about your career, your job, your discipline? My favorite thing about my discipline is that I get to think about human variations. Humans are weird and variable, and I get to just sit back and ask, what did I happen? To me, that's just so much fun.

I enjoy that about my discipline. My favorite thing about my career is that I have cobbled together a weird career where I get to do academic research and I get to do science communication and hang out with amazingly cool people like you, Allie, so that just makes me super happy. Thank you so much for doing this. You are just a joy. Thanks for battling LA traffic to be here. Honestly, it was worth it.

A lot of things are not worth the LA traffic, and I would just stay home, but this was beyond worth it. You're the best. Thank you. Doctor. Oh my God. So ask lovely people ludicrous questions because how are we supposed to know everything if we don't ask?

And Dr. Tina Lissisi is absolutely a gem on earth. We're lucky to know her. You can follow her on social media at the links in the show notes. Her PsyCom is ACES. I enjoy her TikTok so much. Thank you so much, Doc, for being here. There's tons of links up on my website at allieward.com slash ologies slash melaninology. We are at ologies on Twitter and Instagram.

I'm at Allie Ward on both. I'm at Allie underscore ologies on TikTok. So do say hi. Thank you to Aaron Talbert for adminning the ologies podcast Facebook group with assist by Shannon Feltas and Bonnie Dutch. Thank you to Noel Dilworth for all of the scheduling and so much more. Susan Hale handles merch and so much for ologies. Thank you, Emily White of the Wardery for making transcripts available for free at allieward.com

slash ologies dash extras. We have kid-friendly episodes up called Smologies. You can download them all at allieward.com slash Smologies, which is linked in the show notes. Thank you, Zeke Rodriguez-Thomas and Mercedes Maitland for making those. Thank you, Kelly Arduyre for the website help. Huge thanks to my Valentine, Mr. Jared Sleeper, and of course, thank you to lead editor and our favorite Canadian, Mercedes Maitland of Maitland Audio for being the lead editor

on ologies now. Assistant editing was also done by Mark David Christensen, Nick Thorbert wrote and performed the theme music. And if you stick around until the end of the episode, I'll tell you a secret. And this week's secret is that at Tiger Nuts, who's had them? What are these things? Got them at Trader Joe's. They're like these little tubers, and they're really chewy, and you can get them covered

in chocolate. Apparently, they're like tiny potatoes. Some people say that 80% of our ancestors' diets were just Tiger Nuts. Never heard of them before. Obsessed with them. Also, as long as we're telling secrets, yesterday was Valentine's Day, we were supposed to get this up yesterday. And I was too sad.

Absolutely weird grief side swipe. I've been doing pretty well. And then Valentine's Day came around. My dad was always the sweetest on Valentine's Day. We'd leave us little chocolates outside our rooms, little Valentine's. I always, always have loved Valentine's Day. And yesterday, I just, all of a sudden, we went to my friend's house, who just bought a house to go bring her a welcome gift.

And then I went in her backyard and I cried a lot. But I'm feeling better today. Anyway, we're all humans. Tiger Nuts. Delicious. Thank you. Thank you.