Listener Questions #29

Daniel and Kelly answer questions about bark beetles, ambipolar fields, and gray hairs! See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Daniel Whiteson?

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• 2:58Speaker 05

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• 3:13Kelly Weinersmith?

  Beetles and fungi are decimating trees in Seattle. Do any other invertebrates ride fungi into battle?

• 3:21Daniel Whiteson?

  How can the ambipolar field ignore Earth's magnetic might? And why is it stronger on Venus? Could it grow here one night?

• 3:30Kelly Weinersmith?

  Is it true that stress can turn your hair gray? My world is kind of a dumpster fire right now, so I'd prefer if it didn't, okay?

• 3:39Daniel Whiteson?

  Whatever questions keep you up at night, Daniel and Kelly's answers will make it all right.

• 3:45Kelly Weinersmith?

  Welcome to another Daniel and Kelly's Extraordinary Universe, another Listener Questions episode. We've done 29 of these.

• 3:54Daniel Whiteson?

  You know, we haven't actually done 29 of these. This is the 29th.

• 3:58Kelly Weinersmith?

  We're doing the 29th of these.

• 4:01Daniel Whiteson?

  There you go.

• 4:15Daniel Whiteson?

  All right. So my question for you today, Kelly, is when did you start to go gray?

• 4:20Kelly Weinersmith?

  Oh, man. Uh, gosh. A long time ago. I started getting a few random grays towards like the end of undergrad, I think. And then in grad school, it started speeding up. My mom started going gray at 18.

• 4:34Daniel Whiteson?

  Wow.

• 4:34Kelly Weinersmith?

  Um, and so I kind of anticipated it would happen, but I didn't realize that I was really starting to go gray until a friend of mine told me that I was, quote, rocking the salt and pepper look. And I gave him the stink eye because I thought of myself as someone who had a few stray grays. And I hadn't realized I had transitioned to salt and pepper, but it was very nice. And so I, anyway, I've transitioned to salt and pepper, apparently. And what about you? I can't, you've got, you've got some grays, right? It's hard to tell on the Riverside camera.

• 5:04Daniel Whiteson?

  Um, I think I might have one or two gray beard hairs.

• 5:08Kelly Weinersmith?

  Oh, Daniel, that's not fair.

• 5:11Daniel Whiteson?

  I know. But I think I'm still pretty much all original color up top. So.

• 5:16Kelly Weinersmith?

  Wow. Congratulations, Daniel.

• 5:19Daniel Whiteson?

  Yeah. Well, there's some mythology in my family. My grandparents on my dad's side both had jet black hair into their 80s.

• 5:27Kelly Weinersmith?

  Wow.

• 5:28Daniel Whiteson?

  But there's discussion in the family about whether or not they dyed it. And some people are like, oh, of course they dyed it. How naive are you to believe that an 80 year old had black hair? And I don't know, maybe they did. Who knows? I'm not going to exhume their body and do some tests.

• 5:44Kelly Weinersmith?

  Scandalous.

• 5:47Daniel Whiteson?

  But so far in my personal experiment, no grays up top.

• 5:51Kelly Weinersmith?

  Yeah. Cool. I don't know. I don't, I don't really, it doesn't keep me up at night that I have gray hairs. Like, you know, I was, yes, I was a little surprised, but mostly it's just because I'm not very self-aware. But at the end of the day, like, I don't care enough to dye it or anything like that. I'm not losing sleep.

• 6:06Daniel Whiteson?

  And what comes after salt and pepper before you're fully silver haired? Is there another stage there?

• 6:11Kelly Weinersmith?

  I don't think so.

• 6:15Daniel Whiteson?

  So once you're past salt and pepper, you're just all in?

• 6:18Kelly Weinersmith?

  I think then you're at silver fox.

• 6:20Daniel Whiteson?

  Ooh.

• 6:23Kelly Weinersmith?

  And then you go white.

• 6:26Daniel Whiteson?

  And then you're Gandalf.

• 6:28Kelly Weinersmith?

  Yeah, I look forward to becoming Gandalf. I'll get there. The White Wizard.

• 6:31Daniel Whiteson?

  Well, that's the thing is people are like, oh, you haven't turned gray yet. But I think gray adds gravitas. It's nice for people to think you're younger than you are, but then it also makes them take you less seriously sometimes.

• 6:42Kelly Weinersmith?

  Yeah.

• 6:42Daniel Whiteson?

  But something that I do want to take very seriously are the questions in the minds of our listeners, because our goal is to give you a tour of everything that's extraordinary in the universe, but not just the things that we find extraordinary, the mysteries that tickle your minds. So if you have questions about how the universe works, please write to us to [email protected]. Today's questions were taken directly from those messages.

• 7:08Kelly Weinersmith?

  And you'll see that Daniel wasn't just gloating at the beginning of today's episode, although that might have been part of it. We did get a question about graying hair towards the end.

• 7:18Daniel Whiteson?

  Humble bragging.

• 7:18Kelly Weinersmith?

  No, that was just bragging, just straight bragging. There was nothing humble in there, so.

• 7:23Daniel Whiteson?

  That's fair.

• 7:23Kelly Weinersmith?

  All right, so let's move on to question one from Eric, and let's go ahead and hear that question now.

• 7:31Kelly Weinersmith?

  Hey there, Extraordinaries. Eric and I had some technical difficulties, so I'm going to go ahead and read his question. And rest assured, the answer has already been shared with Eric. The question is regarding the spruce bark beetle in Alaska and their relationship with fungus. I understand that they're born with a fungus which is parasitic to spruce trees, which knocks back the immune response of the trees to resist the beetle. The beetles are a delivery mechanism for the fungus. Is this relationship unique to beetles?

• 8:04Daniel Whiteson?

  So he spells beetle B-E-A-T-L-E. Is he talking about the insect or the rock band?

• 8:11Kelly Weinersmith?

  I am going to go ahead and assume that that was an autocorrect, because when I was going ahead and taking notes a couple of times, my phone and Google Docs autocorrected to the band spelling. I guess the band is much more popular than the invertebrates.

• 8:28Daniel Whiteson?

  Well, but there are more kinds of beetles, the invertebrates than beetles, the singers, right?

• 8:32Kelly Weinersmith?

  Yep, yep, many, many. Yes, there's, I think, you know, there's probably something like 6,000 bark beetle species and there's, yeah, far fewer beetle members.

• 8:42Daniel Whiteson?

  And you're not prepared to answer the question if the context were rock musicians?

• 8:47Kelly Weinersmith?

  Yeah, no, that's right. Although I did just listen to, uh, the Rest is History did a few series on the Beatles, but, uh, but no, I'm probably not prepared for, for a whole Beatles episode.

• 8:56Daniel Whiteson?

  All right. So tell us about the bark beetles and their relationship with spruce trees.

• 9:01Kelly Weinersmith?

  Okay. So there's a lot of different species of bark beetles and some of them kill trees. And recently there have been some mass tree die-offs as a result of bark beetles.

• 9:10Daniel Whiteson?

  So sad.

• 9:12Kelly Weinersmith?

  Yeah. But so, you know, a lot of the beetles that are causing these die-offs are native, which I think makes the story a little complicated. So for example, in Alaska, you have the spruce beetle. It's native, uh, and usually it goes after unhealthy trees. And when its population numbers are pretty low, it doesn't cause a lot of trouble. Like it takes trees that were already kind of on the way out, maybe hastens their demise a bit, but that's not a big deal.

• 9:37Daniel Whiteson?

  Do you mean it goes after the ones that are unhealthy like it knows or that it just has success against those?

• 9:42Kelly Weinersmith?

  Oh, good question. I don't know if it's specifically going after the unhealthy ones or if it just is better at the unhealthy ones because trees do have something like an immune system defense.

• 9:53Daniel Whiteson?

  Wow.

• 9:54Kelly Weinersmith?

  Uh, and as we're going to discuss in a moment here, the beetles have a fungus that helps them with that immune system defense.

• 9:59Daniel Whiteson?

  Amazing.

• 10:00Kelly Weinersmith?

  Yeah, but it could be, so you know, the beetles, I don't think they're like randomly, blithely going about their life, not making any decisions. I think they probably can to some extent tell if they are near a tree that is going to be easier or less easy to invade. Uh, and so probably they're, they're searching for the unhealthy ones that they'll have an easier chance with. But at high population numbers, those, some of those unhealthy ones might get crowded and they get pushed out to healthy ones. Let's, let's say that's what's happening.

• 10:26Daniel Whiteson?

  All right.

• 10:26Kelly Weinersmith?

  And so when they get to really high population densities and there's loads of these beetles all over the place, uh, they start killing the healthy trees too. And so for example, there's been an outbreak of these beetles. In Alaska and something like 1.6 million acres have been impacted. And that means a bunch, yeah, many, many, many of these native trees, native spruce trees have been killed in Alaska. And there's another outbreak of the Eurasian spruce bark beetle that's happening right now in Europe, and it's decimating the conifer forests. And so, you know, as I mentioned, a lot of these beetles are native. And so the question is, you know, like, I think a lot of us are bummed out because we like forests and we like trees and

• 11:10Daniel Whiteson?

  Living trees.

• 11:11Kelly Weinersmith?

  Living trees, right. And the idea that beetles are killing a bunch of trees stinks. But I guess the question is, is this a natural process or not? So, you know, when a bunch of trees die, they fall and that clears forest floor to suddenly get sunlight that wasn't getting sunlight before because the trees were blocking it. And now you can get flowers and pollinators. And this is sort of how ecosystems turn over. Ecosystems are not usually stagnant. And so I guess the, the interesting question to me is, is this like a 200 year cycle and we just kind of weren't taking notes before and we're just seeing something that naturally would have happened? Or would the 200 year cycle have included maybe like one hectare of trees dying, but

• 11:56Kelly Weinersmith?

  because of global climate change or because we've managed forests in a way that, you know, has made more trees unhealthy, is it just way more intense than it's ever been in the past? In which case, you know, maybe we care now because we have made this problem much worse than it would have been. Does that make sense?

• 12:12Daniel Whiteson?

  Yeah, but I had the impression that some forests were truly ancient, you know, that forests can be fairly stable. If the climate is stable, et cetera, then trees can grow for hundreds or thousands of years. So it's not like there's a 200 year cycle where all the trees in the forest die and then get replaced. And that's just what we're seeing, right? It feels like we're seeing a shift in the capacity for forests to exist. Right out here in the West, we see lots and lots of dead trees on hillsides and it feels like maybe we're seeing the ends of forests.

• 12:43Kelly Weinersmith?

  Well, first of all, when I said 200, I probably should have said X because I was just picking a number. But, but, uh, so I was listening to In Defense of Plants, which is a great plant podcast, and they had a guy on there who studies bark beetles. And he was saying that like, you know, we really don't know if this is a natural cycle or if it's something that's getting much worse. And, and we do think that probably it is a problem that has gotten much worse. But for a lot of this stuff, we don't have great data.

• 13:08Daniel Whiteson?

  Yeah.

• 13:09Kelly Weinersmith?

  Because if X is a thousand, and it's like a thousand year cycle, we probably wouldn't have great data on that. Maybe every 1,000 years, you do expect to see all the trees on the hillsides dead, and then the cycle starts again or something. But it wouldn't surprise me to hear that we have made this problem worse through global climate change and exacerbating drought and stuff like that. But let's get back to the beetles and the fungus.

• 13:29Daniel Whiteson?

  Yeah, so what are the beetles doing to the trees? And how does the fungus help?

• 13:33Kelly Weinersmith?

  Okay, so the beetles arrive at a tree. And they like, you know, for example, they might go under the bark, and the adults might move around under the bark. And when they do that, they introduce a fungus. And this fungus, the only way it can get from like tree to tree is it travels with the beetles. And so that's how the beetles benefit the fungus. So then the fungus infects the tree. And it does a couple of different things for the beetles. One of the things that it does is that the tree has a bunch of chemical defenses that it would use to make the beetles sick and kill them. And the fungus takes those chemicals that the tree was using to defend itself, and it neutralizes those chemicals. So the tree is no longer toxic to the beetles.

• 14:08Daniel Whiteson?

  Amazing.

• 14:09Kelly Weinersmith?

  Totally agree. Yeah, it's crazy. And now instead, the beetle is starting to convert stuff in the tree to stuff that's nutritious for the beetles. So now it's easier for the beetles to get nutrition from the tree. The beetles aren't getting attacked by the tree. In some cases, the beetles are actually converting some of the things that the tree makes into pheromones to attract more beetles to the tree.

• 14:28Daniel Whiteson?

  Wow.

• 14:29Kelly Weinersmith?

  I know, it's crazy. And so then the beetles lay their eggs in the tree. And if you, you know, if you've worked with like trees before, maybe sometimes you've pulled a piece of bark off, and underneath you've seen all of these sort of like almost random lines that crisscross over each other. Those are the paths of like little baby beetles that have hatched and sort of moved around. And that's like the path of the food that they ate and the movements that they made.

• 14:52Daniel Whiteson?

  Yeah, like these little tunnels that they've dug through underneath the bark. Yeah, it's very cool to see.

• 14:56Kelly Weinersmith?

  Yeah, they're called galleries. And I do feel like they're little works of art like I love that name for them. And so anyway, this reproduction keeps happening and with this collaboration between the beetles and the fungus, the beetles are able to overwhelm the tree's defenses and they can kill the tree that way.

• 15:12Daniel Whiteson?

  Is this something that happens to trees worldwide? This must be a common pattern between beetles and trees. I remember seeing these kinds of patterns on the back of bark of like ponderosa pines in New Mexico, for example.

• 15:23Kelly Weinersmith?

  Yeah, so lots of trees have bark beetles, like at least one bark beetle species. Sometimes you can find more than one beetle species living in different parts of trees. Not all of them are super bad for the tree. And again, a lot of times it depends on how many beetles there are, how bad the condition of the tree is. But yeah, you can find these almost all over the world. It seems to particularly be a problem for like spruces and pines and stuff.

• 15:49Daniel Whiteson?

  Is it ever good for the tree? Are they doing anything that's helpful?

• 15:52Kelly Weinersmith?

  I didn't come across examples of that in my reading. Yeah, it doesn't mean it's not out there. I didn't read every paper on bark beetles, as you can imagine with over 6,000 species. There's a lot of papers out there.

• 16:04Daniel Whiteson?

  Well, I don't know why, but I feel myself rooting for the trees. I mean, I'm not the Lorax or anything and beetles have just as much a right to live and to eat as trees do. But it feels like, you know, the trees have this grandeur and they're supposed to be there and the beetles are invading or whatever. So give me a more ecological viewpoint on this. Why should I not be attached to the trees? Or should I?

• 16:27Kelly Weinersmith?

  Yeah, I think you could argue either way. Like, I mean, I'm attached to the trees and when the trees die, then the like, you know, the woodpeckers that were living in there don't have a home anymore. And like all of the other organisms that depended on those trees are in trouble. You know, I think it makes sense that we get sort of emotionally attached to those forests and all the organisms that live in there. But, you know, the only constant in life is change and ecosystems do pretty regularly turn from one thing to another. And so, you know, expecting a system to stay exactly the same can cause problems. So like one problem that humans have caused is we've tried to suppress fires because we thought, well, fires are bad, but now we've let fuels build up over. And now there's tons of fuel. And so when you do get a fire, it burns extra super hot.

• 17:12Kelly Weinersmith?

  And it kills everything. Whereas before there were some species that would have survived a fire that didn't burn quite as hot. And so, you know, we kind of mess things up when we tinker with it. So the question is, should we tinker with this bark beetle situation? And can we tinker with this bark beetle situation? Like, what could you even do? They're living under the bark and like, you know, what can you do that would target the beetles? Or their fungus without messing with the rest of the ecosystem? Like, it's a really tough problem. And I don't want to make it sound like I'm saying we should throw up our arms and not do anything ever. But just that, you know, these are complicated problems that you need to think about from multiple angles.

• 17:48Daniel Whiteson?

  Yeah, and I definitely have emotional connections to some parts of the ecosystem. You know, like anything that threatens my children, for example.

• 17:55Kelly Weinersmith?

  Oh, yeah.

• 17:55Daniel Whiteson?

  You know, I'm not just gonna be like that. It's in the way of coyotes to tear out the throats of my children. Like, you know, I'm definitely stepping in there and doing something.

• 18:03Kelly Weinersmith?

  I'll note that, um, that, that one, uh, we got an email from PETA encouraging us to, uh, think about things from the animal standpoint a while back. And when I moved out to the middle of nowhere, I did do a lot of research on whether or not it was safe to let my, like, three-year-olds outside with coyotes. I was outside with my three-year-olds and it is very rare for a coyote to go after a three-year-old. But you are encouraged to stay with your three-year-olds outside if there's coyotes around. But once they get bigger, uh, the coyotes are very unlikely to go after them. So your children are safe from coyotes at this age, I would suspect.

• 18:38Daniel Whiteson?

  I hope that's true. Just two days ago, my daughter called me because she was out walking our dog. And there was a coyote that blocked her on a path and she was like, I don't know what to do. So I biked over there and made my presence known.

• 18:52Kelly Weinersmith?

  Oh, that, wait, and so you had to scare the coyote away?

• 18:54Daniel Whiteson?

  Yeah.

• 18:55Kelly Weinersmith?

  Oh, wow.

• 18:56Daniel Whiteson?

  Yeah, they are very brazen in our neighborhood now. They, they roam in packs. They're everywhere. And hey, you know, we moved into their neighborhood, so. On the other hand, I don't really want them eating my kids or my dog.

• 19:08Kelly Weinersmith?

  Yeah.

• 19:08Daniel Whiteson?

  But back to the question at hand, we're talking about fungi and beetles. One question I had is, these beetles are using the fungus to help colonize the tree. What's in it for the fungus? And what's happening when the beetles are not in a tree? Or are the beetles never not in a tree?

• 19:24Kelly Weinersmith?

  The beetles are pretty much always in a tree or moving from one tree to another, and the fungus get transport. So the best way for the fungus to get from one tree to another is by being moved by the fungus. That's the main thing we think that they get from it.

• 19:37Daniel Whiteson?

  Okay, and are beetles the only ones who do this kind of fungus farming?

• 19:41Kelly Weinersmith?

  No.

• 19:41Daniel Whiteson?

  Really?

• 19:42Kelly Weinersmith?

  Yeah, so Eric wanted to know, you know, what other invertebrates collaborate with fungi? And it turns out that there's quite a few invertebrates that collaborate with fungus. And so fungus farming is a pretty common thing in the invertebrate world. Daniel, I have a question for you. Termites, you look at termites.

• 20:00Daniel Whiteson?

  Yeah.

• 20:01Kelly Weinersmith?

  What do you think termites are closely related to if you had to guess?

• 20:04Daniel Whiteson?

  Hmm, termites.

• 20:05Kelly Weinersmith?

  Or do you already know the answer to this?

• 20:07Daniel Whiteson?

  I do not know the answer.

• 20:09Kelly Weinersmith?

  Okay.

• 20:09Daniel Whiteson?

  They're an insect because of the legs. They got all those little segments. They seem kind of anty to me.

• 20:15Kelly Weinersmith?

  Thank you. Yes, they do look anty to me. And I, and so I said something to one of my friends about them being, you know, kind of ant-like. And they were like, Kelly, they're more closely related to cockroaches.

• 20:27Daniel Whiteson?

  What? Oh, no.

• 20:28Kelly Weinersmith?

  And I looked at them for a second and I kind of gave them a little bit of the stink eye because I was like, you are either messing with me or I should be very embarrassed. Because I am way off here. And it turned out I was way off.

• 20:42Daniel Whiteson?

  Well, I don't have to be embarrassed because I'm not supposed to know, so.

• 20:45Kelly Weinersmith?

  No, well, yeah, I wasn't trying to embarrass you like you were trying to embarrass me about my gray hair earlier, but, ooh, slice.

• 20:52Daniel Whiteson?

  I'm impressed by the gravitas your gray hair lends to you.

• 20:55Kelly Weinersmith?

  Oh, thank you. Yes, I look very mature and commanding of wisdom and whatnot.

• 21:00Daniel Whiteson?

  Exactly.

• 21:02Kelly Weinersmith?

  All right, so fungus farming is seen in some termites, ants, wood wasps and ambrosia beetles. So basically the deal here is that they collect certain kinds of fungus. They put fungus in a certain area sometimes. For example, there are like leaf cutter ants who will feed the fungus certain kinds of leaves and then the fungus will break it down into things that are more digestible for, you know, for example, the leaf cutter ants. So let's talk about the ambrosia beetles for a second. So the ambrosia beetles will farm fungus and they will bring them into, for example, like dead trees. And then they'll create those galleries that we were talking about and they'll sort of lay their eggs, they'll have their babies and the fungus will be like.

• 21:47Kelly Weinersmith?

  Creating food for everybody. And the Ambrosia beetles even have little specialized parts on their bodies so that they can carry the fungus with them from one place to another. And so this is like a very close symbiosis. So they can, you know, can bring it from one place to another. But while I was reading about this, I discovered a cool concept called mycokleptism. And so while some Ambrosia beetles will bring the fungus with them from place to place and will essentially live with the same strains of fungus for their whole lives. Other beetles will steal fungus from others. And so there are some beetle species who will find an Ambrosia beetle who's doing a good job of farming their own fungus. They're being good farmers, good stewards of the land.

• 22:32Kelly Weinersmith?

  And then the mycokleptics will, uh, will come in and they'll steal some of the fungus and they'll start farming it on a different part of the log, kind of close by. They'll lay their own eggs in there.

• 22:43Daniel Whiteson?

  Wow.

• 22:43Kelly Weinersmith?

  And they'll essentially steal the fungus. And so they don't, they're not born with this fungus. They take it from another organism, uh, over the course of their lives.

• 22:51Daniel Whiteson?

  Hmm. Wow. That's a little creepy.

• 22:54Kelly Weinersmith?

  It's a little creepy. Yeah. Yeah. It's like your family stealing beans from another family or something, you know?

• 23:01Kelly Weinersmith?

  Cause you guys have a close symbiosis with beans and chia seeds.

• 23:06Daniel Whiteson?

  That's true. We do. We are lovers of fermented foods and fiber over here.

• 23:10Kelly Weinersmith?

  Mm hmm.

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• 25:21Speaker 02

  Hey, it's Nile Rodgers, host of Before the Moment, a Lincoln original series. I'm driving across the country, meeting some of today's most fascinating artists. We're exploring the stories before the moment that changed everything. This week, I'm joined by Miguel. That last year, finishing that record, was the hardest experience of my life. Find your creativity and to believe in yourself because somewhere in the midst of it, I stopped believing that my voice mattered and that I could find it again. That's a challenge. I was not feeling very confident creatively, only, again, defiant

• 26:06Speaker 02

  in my belief that what this is about is express something honest. Say something honest. Experience before the moment. A Lincoln original series on the iHeart Radio app, YouTube, or wherever you get your podcasts.

• 26:35Daniel Whiteson?

  Okay, we're back and we're answering questions from listeners today. Questions about Beatles, questions about space, questions about what's going on on Kelly's cranium.

• 26:45Kelly Weinersmith?

  On my cranium? How did we get to talking about my cranium?

• 26:48Daniel Whiteson?

  Are we gonna be talking about gray hairs, salt and pepper, silver foxes later?

• 26:52Kelly Weinersmith?

  Oh, yeah. Okay, we're back. We're back to my gray hairs. Are we gonna talk about my crow's feet too? Is there anything else you want to point out that's wrong with me, Daniel?

• 27:01Daniel Whiteson?

  I never noticed any crow's feet, Kelly. This is the first I hear about them.

• 27:04Kelly Weinersmith?

  No, no, you're not. You can't walk back the problem you started earlier today, Daniel. All right, let's, let's change the subject and hear what Jane has to say.

• 27:17Speaker 03

  Hi there, Daniel and Kelly. I've recently heard about the ambipolar field and I'm fascinated to know more. It seems to be independent of the Earth's magnetic field, but I don't understand how that can be. Can you explain? I've also heard that the field is much stronger on Venus, and that's one reason why Venus no longer has oxygen or hydrogen in its atmosphere. But why is it stronger on Venus than on Earth? And was it always that strong? If not, might it increase on Earth? I'm loving the show and being able to ask questions. Like having a tin professor in the spare room.

• 28:01Speaker 03

  So I'm really looking forward to hearing your answers to my questions. Thank you.

• 28:06Daniel Whiteson?

  All right. So Jane has a really fun question about electric and magnetic fields around the earth. And this is a field I think a lot of people haven't heard of.

• 28:15Kelly Weinersmith?

  Yeah, I don't think that I've heard, or if I have, I've forgotten about the ambipolar field. Right. So I'm thinking about ambidextrous and you can switch between left and right. Is that, is that helping me understand ambipolar? Cause it can it's no, no. Okay.

• 28:31Daniel Whiteson?

  So most people are familiar with earth's gravitational field, right? In a Newtonian picture, gravity is a force and it pulls on stuff. And things with more mass get pulled on more strongly. And that's what holds the atmosphere in place, for example, or earth's magnetic field. Magnetic fields are generated by charges in motion. So like currents of magma and other metals inside the earth, we think generate the magnetic field. Not fully understood with all sorts of weird behavior, like the poles move and the poles flip, all this kind of stuff. The ambipolar field is something completely separate from both of those. It's a totally separate effect coming from atoms in the atmosphere being ionized.

• 29:12Kelly Weinersmith?

  Oh, all right. So is this going to have anything to do with the aurora borealis?

• 29:18Daniel Whiteson?

  Not directly, no, but a little bit, you know, a little bit. So what happens is if you have a neutral particle, like you have a proton and an electron, they're bound together. They make hydrogen, for example, everything is happy. But sometimes things get hot and electrons leave their protons. And now you have ions, protons that are positively charged and electrons. Electrons are negatively charged and they're separated. So this is like a plasma. And in the upper atmosphere, you have high speeds and not everything is bound together. So there's lots of protons and electrons up there. It's not just all neutral atoms. So now you have the gravitational force, it's going to pull harder on the protons than it is on the electrons. Why? Because protons are much more massive than the electrons.

• 30:03Kelly Weinersmith?

  I remember that.

• 30:04Daniel Whiteson?

  Mm hmm. And so what that means is that protons are Lower in the atmosphere than electrons. You get this separation because electrons are lower mass. They're moving faster with the same kinetic energy. So essentially you get an imbalance, right? Now you have the electrons higher up than the protons. That creates an electric field because you have these charged particles. And when you create a separation of charges, you get a field between them. Because essentially there's a force that wants to pull them back. That is an electric field, the ambipolar field in the upper atmosphere of Earth and also Mars and also Venus. So that's what the ambipolar field is.

• 30:42Kelly Weinersmith?

  Whoa, okay. All right, so first of all, can you use that for anything?

• 30:47Daniel Whiteson?

  You can use it to create like a gun of particles out into space. So for example, this field will pull on particles. It'll pull protons up. And in some parts of the Earth, it'll create like a polar fountain. And like at the North Pole, it creates like a font of hydrogen atoms, hydrogen ions, actually, shooting up and out of the Earth. I don't know if that's useful for anything, but it's kind of cool.

• 31:11Kelly Weinersmith?

  Okay, yeah, neat.

• 31:12Daniel Whiteson?

  And you could also in principle, use it to help like steer satellites. You know, this one way to steer satellites, instead of having thrusters, you still like use the Earth's electric and magnetic fields. Like you have a long tether and you twist it and that creates torque. Or you can use it to create thrust. It's fairly weak, though, so not like big satellites or anything. But you know, it adds to the sort of texture of the near Earth environment.

• 31:37Kelly Weinersmith?

  Okay, awesome. And then, okay, so you, so Earth, Mars and Venus have it. All right, so what are they? All right, so they all have gravity, but every planet has gravity. They all have atmospheres, so you need an atmosphere.

• 31:50Daniel Whiteson?

  Although Mars's atmosphere is much, much weaker. So its ambipolar field is also weaker.

• 31:55Kelly Weinersmith?

  Yeah, and Mars is like, what, 1% of Earth's or something?

• 31:58Daniel Whiteson?

  Yeah, exactly.

• 31:58Kelly Weinersmith?

  Is that all you need is a gravitational field and an atmosphere to have an ambipolar field?

• 32:03Daniel Whiteson?

  That's almost all you need. You need ions in your atmosphere also, right? If it's all neutral particles, you're not going to get an ambipolar field. And that's one reason why Venus has a much stronger ambipolar field than Earth. Number one, it has a very dense atmosphere. So there's a lot of electrons and ions to pull apart. But also, because Venus has no magnetic field, has no protection from the solar wind. See, we're going to get to the aurora borealis connection. And the solar wind is what creates a lot of these ions in the upper atmosphere. So you have energy from space, photons and protons, et cetera, hitting the upper atmosphere. That's ionizes it. That energy from space breaks open neutral atoms to create your ion and your electron.

• 32:45Daniel Whiteson?

  And because Venus doesn't have a magnetic field to protect it from the solar wind, a lot of that solar radiation causes more ionization and speeds up those particles because all this energy is coming from space. And so that gives you a lot of ions, and those ions are now moving fast. And so that helps these ions escape. So that creates the very strong ambipolar field on Venus. And this is always sort of counterintuitive, like the electrons get higher, the protons get lower. And so that's the amper polar field. But then the effect on the other particles is the opposite. That field is always trying to cancel itself out. Electromagnetism is always doing whatever it can to cancel itself out because it's so strong. So you create that field by separating them.

• 33:29Daniel Whiteson?

  Then the field has the effect of pushing the ions up and the electrons down, which is why you get this like font of hydrogen ions. In a similar way, sort of that if you immerse a metal in an electric field, the electrons in that metal will move to counter that electric field because the electric field has pushed on those electrons. Right? So electromagnetism is always doing everything it can to zero itself out. It doesn't want to ever do anything. It's just so lazy.

• 33:55Kelly Weinersmith?

  Okay, so it's stronger on Venus. So is it stronger on Venus for two reasons? One, Venus has a thicker atmosphere. And two, you're more likely to have charged particles in that atmosphere.

• 34:08Daniel Whiteson?

  Yes, exactly. So it's not directly connected to the magnetic field. It's not caused by the magnetic field. In that sense, I think that was Jane's question. But it is indirectly connected because the magnetic field will help you prevent ionization of your upper atmosphere, which would reduce the amper polar field.

• 34:24Kelly Weinersmith?

  Okay.

• 34:25Daniel Whiteson?

  And so Venus has a strong one because two- Reasons, yes, has a denser atmosphere and it doesn't have protection from the solar radiation. Now, we think that a long time ago Venus was a very different situation. It might have had a magnetic field before its internal bits seized up and it cooled. It might have had internal motion which generated a magnetic field which shielded it from some solar radiation, which would have had less ionization. Now it's lost that magnetic field, so it gets more radiation and a stronger field.

• 34:54Kelly Weinersmith?

  Cool. Okay. Now, could Earth get a stronger ambipolar field?

• 35:00Daniel Whiteson?

  Yes, it's possible that our ambipolar field could increase, but for that to happen, we'd essentially have to lose our magnetic field. We'd have to be more susceptible to solar radiation.

• 35:11Kelly Weinersmith?

  No, thanks.

• 35:12Daniel Whiteson?

  So that could either be we lose our magnetic field, which seems unlikely. I mean, we don't really understand it and it's been kind of flip flopping and sloshing around, but total loss of the magnetic field would require the Earth's internal mechanisms to seize up the way Mars has and Venus has. And that seems unlikely to happen soon because there's still plenty of activity going on inside Earth. If it happened, it would be slow and gradual. Or the other thing is we could have more solar radiation, so we could get more ionization. And that's more unpredictable. Like, that just depends on, hey, is the sun gonna burp at us some huge blob of plasma that comes and strips away a lot of the atmosphere or ionizes it? That could happen at any moment. You know, just a few weeks ago, we had really

• 35:55Daniel Whiteson?

  strong aurora boreali. Is that how you pluralize it? You could see them pretty far south in the United States because of the space weather event from the sun. And that comes from not understanding the internal dynamics and the chaos of the sun's plasma well enough to predict that. So, yeah, we could get a stronger ambipolar field if we got more solar radiation, or if we weakened our protection from it. Either one would give us more ions and therefore a stronger ambipolar field.

• 36:21Kelly Weinersmith?

  Neither one of those options sound great for the humans living here. So, let's, let's hope it doesn't happen.

• 36:28Daniel Whiteson?

  All right, well, let's send that answer to Jane and hear if it freaked her out or made her feel more at one with her understanding of the universe.

• 36:36Kelly Weinersmith?

  And let's hear if she's going to kick the professor out of her spare room.

• 36:41Daniel Whiteson?

  Thank you so much for your answer, Daniel. I really feel I understand the ambipolar field now, and I'm very relieved that we're, for the most part, protected from Venus's fate by our wonderful magnetic field. But I do love the idea of a polar fountain. Sounds like something Santa would have.

• 37:03Speaker 02

  Oh, and by the way, my spare room is still available for professors if you're ever in the north of England. Thanks for a great show.

• 37:20Speaker 02

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• 39:11Speaker 05

  Talk to your doctor. Call 1-800-545-5979 or visit zepbound.lily.com.

• 39:19Speaker 02

  Hey, it's Niall Rogers, host of Before the Moment, a Lincoln original series. I'm driving across the country, meeting some of today's most fascinating artists. We're exploring the stories before the moment that changed everything. This week, I'm joined by rising star Sienna Spider. I love the 60s. I feel really jealous that I wasn't alive for it. I'd be interested, like, knowing what that was like and seeing the way culture and art has progressed today. How do you find it? Wait a minute. I'm sorry, I have so many questions. Sorry. You're not nervous, are you? I am nervous. You are? I am. I feel, like, insecure about my experience. I know I shouldn't, but, you know, I'm 20. I haven't really lived my life yet.

• 40:02Speaker 02

  And then sitting in front of somebody that has lived an enormous life is intimidating. And sometimes I feel like talking about myself is just not as interesting. So that's why I feel a bit nervous. I'll try and ignore it, though. Please do. Experience Before the Moment, a Lincoln original series on the iHeartRadio app, YouTube, or wherever you get your podcasts.

• 40:34Kelly Weinersmith?

  I don't know, Daniel, if you had a professor in your spare room for questions, would you want a physicist? Or maybe a less smelly profession?

• 40:43Daniel Whiteson?

  We often have a professor in our spare room because we have a guest room and people come to visit and sometimes, you know, you invite a friend to come and visit for official reasons, to give a talk, but then you also want to hang out with them and you don't want to put them up in a hotel. So they sleep in our spare room and have dinner with us and that's a lot of fun. So often, we have biologists and physicists, or physicists usually, coming to stay with us. And our kids have expressed their lack of enthusiasm for physics or biology dominated dinner conversations.

• 41:15Kelly Weinersmith?

  Our kids at some point asked us to please stop talking about space law over dinner. Yeah, I understand. All right, let's move on to our question from Joe.

• 41:25Speaker 02

  Hi, Daniel and Kelly. I've often heard the claim that stress made me get all these gray hairs. Is there any biological validity to that concept? And if so, what are the mechanisms? Can your emotional state plus cortisol or dopamine levels perhaps affect this part of your biology? Finally, has it been observed in any other animals? Thanks so much for bringing some color or salt and pepper to this question.

• 41:51Daniel Whiteson?

  All right, so Joe's suggesting that gray hair isn't just about age, it might be about stress. It's about like emotional age, not, you know, cosmological age.

• 42:00Kelly Weinersmith?

  That's right. And so I think it's possible that there are different mechanisms at play here. So let's go ahead and leave my old age related grays to the side. We don't, we don't have to talk about them anymore, actually.

• 42:12Daniel Whiteson?

  Okay, all right.

• 42:14Kelly Weinersmith?

  And so to understand what's happening, let's go ahead and talk about the hair cycle. All right, so you have loads of hair follicles on your head.

• 42:24Daniel Whiteson?

  I do.

• 42:25Kelly Weinersmith?

  You do, you do.

• 42:27Daniel Whiteson?

  One does.

• 42:27Kelly Weinersmith?

  Not only is your hair not gray, but you actually have it covering your whole head. You are very lucky for a 50 year old. Or are we rounding up to 100 now?

• 42:37Daniel Whiteson?

  Yeah, exactly. I'm more than 50, so it rounds up.

• 42:40Kelly Weinersmith?

  Okay, all right. So each of our hair follicles goes through a cycle and our hair follicles aren't synced. So our hair follicles tend to be at different stages of this cycle. Anagen is the part of the cycle where your hair is growing. And for the hair on top of your head, the stage usually lasts about four to six years.

• 43:00Daniel Whiteson?

  Oh, that's all?

• 43:01Kelly Weinersmith?

  Yeah, yeah, kind of surprising, right? And your hair is growing something like half an inch a year. And early in anagen, what happens is that you have hair follicle stem cells. And so stem cells are cells that are, they're like, they're like baby stem cells. There's things that they can become, but they haven't become them yet. And these are cells that are going to become hair follicles, but they haven't become them yet. So they're hanging out there and when the time comes, they will become hair follicles. And they're just waiting for the message. When you get to this early growth phase, these hair follicle stem cells jump into action. They make a hair follicle and now you've got your hair follicle.

• 43:40Daniel Whiteson?

  All right, so I have stem cells on my scalp my whole life, waiting to become follicles. Cool, didn't know that.

• 43:46Kelly Weinersmith?

  And you also have melanocyte stem cells. And so what they're doing is they're waiting to produce melanocytes. And these are the cells that make melanin, which is the pigment that gives hair color. And so early in anagen, your hair follicle is being made and your melanocyte stem cells are activated to make melanocytes. And the melanocytes will travel down to your hair follicle and they get ready to start making melanin. So now your hair follicle is making the hair, your melanocytes are making the melanin. And now you have hair that has color.

• 44:26Daniel Whiteson?

  And all of my melanocytes have to all be coordinated, right? Because I have like one color of hair on my head and you have a different color of hair. And my daughter is blonde, for example. And so there's a genetic coding in there that controls all of the melanocytes or melanocytes?

• 44:42Kelly Weinersmith?

  Melanocytes, yes, they're all making the same color.

• 44:45Daniel Whiteson?

  I see.

• 44:46Kelly Weinersmith?

  Yeah.

• 44:46Daniel Whiteson?

  Okay, so the thing that's confusing to me is if they only last for four to six years, how come I didn't lose all my hair when I was seven?

• 44:53Kelly Weinersmith?

  Because there's a cycle. Okay, so you've got four to six years and then you go into a phase called the catagen phase. Where everything sort of degenerates. You lose the blood vessels. And so now the hair follicle isn't getting oxygen or nutrients. And this lasts about two weeks. And at this stage, the melanocytes die. But your melanocyte stem cells are still alive. So you still have cells that can make more melanocytes. But the melanocytes that were made a few years ago, they're toast.

• 45:22Daniel Whiteson?

  Okay.

• 45:23Kelly Weinersmith?

  Okay, and then you go into a resting phase. And this can last for a few months where the hair follicle is just kind of chilling out. And then you go into a phase called exogen, where the original hair is shed out because you've started the cycle again. A new hair is growing and it pushes out the old one. You shed, so you shed something like 50 to 100 hairs a day. And so that's how many hairs are sort of beginning the process anew. And when you start that process anew, those two types of stem cells wake up again. They start doing their jobs again. And after the new hair follicle has started, and after the new melanocytes are have gone to work, those two sets of stem cells go to sleep again for like, you know, four to six years or whatever. They they do their job. They make the cells that are going to work through the cycle.

• 46:08Kelly Weinersmith?

  And then the stem cells go to sleep. Does that make sense?

• 46:11Daniel Whiteson?

  That makes a lot of sense. And it really helps me understand something I remember wondering about when I was like a teenager. Young physicist Daniel was thinking about hair growth, the way you think about like radioactive decay. You know, I was thinking maybe it was like probabilistic and hairs would just like fall out randomly. But if that were the case, you'd start with like a full head of hair. And then you just gradually lose hairs until eventually you had like one super long hair, which would be the only thing you had. Clearly, that model does not explain the data. So I like your model a lot better.

• 46:41Kelly Weinersmith?

  Oh, good. Okay. Well, and there's a lot of variability. Some people have, you know, shorter cycles, so their hair doesn't grow as long.

• 46:46Daniel Whiteson?

  Right.

• 46:46Kelly Weinersmith?

  And the cycle on your body is much shorter. So your body hairs never get as long as the hairs on your head. But this is like sort of generally our understanding of how the cycle goes on average.

• 46:56Daniel Whiteson?

  All right. And so there's really two different bits there. There's like the hair growing and the hair coloring. And so tell us about why the hair coloring can go wrong or why things turn gray.

• 47:07Kelly Weinersmith?

  All right, so I found this amazing paper. Zhang et al. 2020 in Nature did this amazing set of experiments that sort of like deal with tons of different hypotheses. And they really nail it down in mice. So again, this is in mice. Keep in mind, it's in mice, not in humans. But okay, so first they say. If you stress out black mice, will they get gray hairs? So they stress mice out a couple of different ways and the mice do start going gray.

• 47:33Daniel Whiteson?

  Are they terrible?

• 47:34Kelly Weinersmith?

  Uh, no, I mean, they're not. They're not the worst I've read about.

• 47:39Daniel Whiteson?

  I have to imagine, how would I stress out a mouse? I might like put it in a cage next to a cat. Not to kill it, but just to like, put it in the cage next to it. That would be pretty stressful for a mouse.

• 47:49Kelly Weinersmith?

  Oh, okay. So no, this is nowhere near that bad, actually. So they, they would rapidly change the light and dark cycles. They would leave the bedding be a little bit damp. They would have the cage be sort of tilted. They'd leave them in a cage by themselves and they're kind of a social species. So nowhere near as bad as what you're thinking.

• 48:07Daniel Whiteson?

  That's very gentle, yes.

• 48:08Kelly Weinersmith?

  That is, yes, yeah. And again, as we've discussed multiple times on the show, before you do experiments like this, you need to get animal care and use protocols. And we understand you have to stress the animals out to test the hypothesis, but you've got to do it in the most humane way possible.

• 48:21Daniel Whiteson?

  Good, okay.

• 48:21Kelly Weinersmith?

  But the most effective and fast method they found for stressing the animals out was to give them an injection of a capsaicin analog under their skin. So capsaicin.

• 48:32Daniel Whiteson?

  That's spicy?

• 48:32Kelly Weinersmith?

  That's spicy, yeah. That's the stuff that gives you the spicy feeling if you're eating peppers or something.

• 48:37Daniel Whiteson?

  So they would like internally pepper spray these mice?

• 48:39Kelly Weinersmith?

  Yeah, you always find the most horrible way to say these things when we talk about animal studies. But I am going to just use the phrase, "the injection" for the rest of this description.

• 48:51Daniel Whiteson?

  If that makes you feel better, Kelly, all right.

• 48:53Kelly Weinersmith?

  All right, well, do you want to know the answer to this or not?

• 48:55Daniel Whiteson?

  Yes, I do, please, thank you.

• 48:57Kelly Weinersmith?

  All right, so they inject mice with this capsaicin analog and the mice did get gray, but they got like salt and pepper gray, like me. So it wasn't, they didn't turn completely gray. It wasn't patches. It was exactly what you would expect if you had hair follicles on random cycles and some of them started turning gray.

• 49:15Daniel Whiteson?

  And did they look at the microbiology of it? Like, can they see the melanocyte dying or doing something or giving up or?

• 49:21Kelly Weinersmith?

  Yeah, so that's the next thing that they did. So next they said, okay, we know that the, we've got these mice that will turn gray sort of like humans do, so what's happening? So then they, they decided they were gonna, for the stressor, they were going to just keep using this injection. So then they use the injection and they look. At what was happening with the melanocyte stem cells and with the melanocytes. And what they found was that the melanocyte stem cells were like disappearing.

• 49:47Daniel Whiteson?

  Oh.

• 49:47Kelly Weinersmith?

  But the melanocytes were staying where they were.

• 49:50Daniel Whiteson?

  Mm hmm.

• 49:51Kelly Weinersmith?

  And so all of the melanocytes that had already been made were fine. They kept making the black pigment for these black mice, but the melanocyte stem cells were gone. So the next time a phase started again, no new melanocytes were made and those hair follicles would become gray.

• 50:06Daniel Whiteson?

  So gray is the default color. If you don't have a melanocyte, then it's just gray.

• 50:10Kelly Weinersmith?

  Yes, right. And so they're like, okay, where did these melanocyte stem cells go that are supposed to be there to make sure you've got the cells to give you color every time the cycle starts again? So that was the next question that they wanted to ask. And so one idea that's been going around for a while is that when you get stressed out, something about your immune system attacks your like hair follicles. And something about that makes it so that your hair goes gray. And so we've done so much work on mice in the lab now that you can just like pop open a mouse catalog and you can order mice that like have various parts of their immune systems that don't work anymore.

• 50:48Daniel Whiteson?

  Wow.

• 50:48Kelly Weinersmith?

  So they like ordered some mice that don't have T cells or don't have B cells or like they're lacking various parts of their immune cells.

• 50:54Daniel Whiteson?

  Meaning that there's like an industry that manufactures mice with specific deficits that are useful for scientific experiments.

• 51:01Kelly Weinersmith?

  Yes, yeah.

• 51:02Daniel Whiteson?

  Amazing.

• 51:03Kelly Weinersmith?

  So they essentially ordered some mice who don't have like good immune systems in a variety of different ways. And they gave them these injections and they still went gray. So that was pretty good evidence that it's not something about the immune system that's important for creating this gray. So the next question they wanted to know was, okay, well, is it something about stress? And usually when you are thinking about stress, you think about cortisol or noradrenaline. So cortisol is a hormone that humans make and we release it in times of stress. And what it does is it helps us like mobilize energy. So for example, if you're being chased by a lion, you want to make sure you've got as much energy available, as many, you know, as many like calories that you could send to your muscles or whatever.

• 51:48Kelly Weinersmith?

  So that you can run away from that lion. It's not going to make you faster than you usually would be, but as fast as you're able to be, they want to make sure that you can be to try to get away from that lion. And then after that stressor, it tries to help your body like recover from this massively horrible thing that just happened to you. And so for us, that hormone is called cortisol. Mice have a closely related version called corticosterone. And so they wondered, okay, maybe it's something about corticosterone that causes graying. And so it turns out that the melanocyte stem cells have receptors for corticosterone. And so what that means is that these stem cells can bind to corticosterone. And what usually happens when a receptor binds to a hormone is that that hormone is sending

• 52:30Kelly Weinersmith?

  some message to the inside of the cell that the cell needs to do something. And usually what that something is, is like, you need to go into your genetic blueprints and start making some new compound.

• 52:42Daniel Whiteson?

  Yeah.

• 52:42Kelly Weinersmith?

  Yeah. So what they did amazingly is they said, okay, we're going to essentially take the receptors off of the melanocyte stem cells. And now we're going to inject the mice with the capsaicin analog and see what happens. And those mice still got gray hairs. So it wasn't about the glucocorticoid stress hormones, because even when that hormone can't talk to the melanocyte stem cells, you still get gray hairs. Are you with me? Because this is kind of confusing, but it's beautiful how they're doing this step by step.

• 53:15Daniel Whiteson?

  I didn't follow glucocorticoid, but I think I do understand the argument here is that these melanocyte stem cells, the things that you need in order to make new melanocytes, are disappearing and they have a button on their outside that responds to this stress hormone. But when they disabled that button, it didn't change anything. So they don't think that pressing that button due to stress is killing these melanocytes.

• 53:39Kelly Weinersmith?

  Thank you. Yes, that's a great way to say it.

• 53:40Daniel Whiteson?

  Okay.

• 53:40Kelly Weinersmith?

  Okay, perfect. And they have another button for noradrenaline. And noradrenaline is just another chemical your body makes when you're stressed out, but it comes from different places. It can either come from your sympathetic nervous system. So it can come from nerves that talk to your hair follicles. Or it can come from these glands that sit on top of your kidneys. They figured out that if you remove this button for noradrenaline, they don't turn gray. And they figured out that the message is not coming from on top of the kidneys. The message is coming from the nerves. I'm simplifying a little bit because I realized I was getting a little too in the weeds. But anyway, it is coming from the nerves.

• 54:21Kelly Weinersmith?

  And they were actually able to like use this neurotoxin to keep the nerves from sending the message to the hair follicles. And they didn't turn gray when you like messed with the nerves. So it's definitely the nerves that are sending the message to the melanocytes that is essentially making the melanocytes disappear.

• 54:40Daniel Whiteson?

  And what's the connection then with stress? Is something about the stress that makes the nerves send this message?

• 54:46Kelly Weinersmith?

  Yeah, so you stress someone out. Their sympathetic nervous system, their fight or flight system is like, ah! And they've released noradrenaline and that noradrenaline binds to the melanocyte stem cells. So you're, the button on the melanocyte stem cells has been pushed. But if they are in the phase where they're supposed to be sleeping, you've woken them up from their sleep and they kind of freak out. And instead of, I don't know, going back to sleep, they start doing something totally unexpected. They all start turning into other kinds of cells. I think they're turning into melanocytes and then they migrate away. And so by the time this, this process is done, you don't have any more stem cells.

• 55:31Kelly Weinersmith?

  They've, they've all done what's called differentiated, which is a fancy way of saying they've turned into a final version of a cell and they can't make new like melanocytes anymore. And then they migrate away and so they're not there anymore. The next time your hair cycle starts again, they've wandered off for reasons we don't understand. And so something about freaking out from some stressful event totally like discombobulates your melanocyte stem cells and they wander off.

• 55:58Daniel Whiteson?

  So that makes sense as a mechanism to explain why this happens. But why would melanocyte stem cells have this button? Why are they sensitive to the presence of these stress hormones?

• 56:08Kelly Weinersmith?

  We don't know.

• 56:10Daniel Whiteson?

  Oh.

• 56:10Kelly Weinersmith?

  Yeah, so there has been a connection between pigment producing cells. Like melanocytes and our nervous system for, you know, like a really long stretch of evolution. So for example, octopuses and other cephalopods, if you stress them out, they will talk to their pigment producing cells to like change colors, kind of like blend in with the environment. But that doesn't explain why we have nervous systems that are like talking to our melanocytes and our hair follicles. But there, there is this like long connection. Maybe there's some reason why it still benefits us that we don't know. But when I read the discussion of this paper from 2020, they were pretty much like,

• 56:51Kelly Weinersmith?

  not really clear why this is happening, like what the evolutionary benefit would be. Maybe it's something that was beneficial. Millions of years ago, and there was just never a reason to decouple. These connections.

• 57:03Daniel Whiteson?

  Maybe it's not so bad for people who have experienced stress to advertise that by showing off their gray flowing locks. So people know, oh, you know, Kelly's been through something. Let me ask her opinion.

• 57:14Kelly Weinersmith?

  That's what she's probably wise because she experienced. Yes, right. Grad school gave her gray hair. She can tell us to not go.

• 57:24Kelly Weinersmith?

  No, I had fun in grad school.

• 57:25Daniel Whiteson?

  And so is this only something that happens in mice? Or is the same mechanism happen in other animals like in people?

• 57:32Kelly Weinersmith?

  Uh, I think it happens in other animals too. Like, I mean, I, dogs definitely go gray. I don't know if they go gray for stress, but like, I think if it's happening in mice, it's probably happening in other animals too. So I'm guessing this is a pretty common thing.

• 57:44Daniel Whiteson?

  And this suggests there might also be a treatment available there. You could somehow protect those myocytes. So they don't get that button pressed.

• 57:51Kelly Weinersmith?

  Yeah. So one I want to note that it's really refreshing to have you be the one mispronouncing a word for once. I'm like feeling great about that. Uh, and I guess we, you know, we both give as good as we get in terms of picking on each other. But, um, but yes, it does suggest that if somebody has had like a super stressful experience, maybe you could try to calm them down in some way quickly in a way that might rescue their melanocyte stem cells. You'd have to do that pretty fast because once those stem cells have migrated away, there's, they don't come back. Yeah, then you've lost them forever.

• 58:24Daniel Whiteson?

  Wow. Fascinating.

• 58:25Kelly Weinersmith?

  I really appreciate this question, Joe, because this was like, this was so much fun to read about. Like, there were lots of things in this paper where I was like, I have no idea what you're saying. This is like crazy molecular biology stuff. But like, wow, this was a cool set of experiments that really like, anyway, I am going to try to make sure nothing super stressful happens to hasten my decline into silver fox hood. But I'm sure I'll rock it either way.

• 58:49Daniel Whiteson?

  Well, fortunately, it doesn't sound like answering this question was that stressful for you, which is a relief. So let's send it over to Joe and hear about whether it gives him any more gray hairs.

• 58:59Speaker 04

  What a colorful journey to finding that association. I'd like to mention that this kind of science, where the search for an answer becomes a series of experimental steps, is research of the best kind. It's also one everyone can do in their own way. Thank you for getting to the root of this question without stressing anyone out. In the same vein as Kelly, I too have a few hairs of wisdom. That said, I'm definitely still going for the spicy foods. Whether your head is black, blonde, bare, or glistening gray, stay chill, everyone.

• 59:32Daniel Whiteson?

  All right. Thank you very much, everybody who sent us questions. We really do love hearing from you. And one reason is that it gives us an excuse to dig into some corner of physics or biology that we always wanted to understand and never had a reason to spend an afternoon on. So thank you very much, everybody, for being curious and for sharing that curiosity with us.

• 59:51Kelly Weinersmith?

  Thank you.

• 59:58Kelly Weinersmith?

  Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you.

• 1:00:04Daniel Whiteson?

  We really would. We want to know what questions you have about this extraordinary universe.

• 1:00:10Kelly Weinersmith?

  We want to know your thoughts on recent shows, suggestions for future shows. If you contact us, we will get back to you.

• 1:00:16Daniel Whiteson?

  We really mean it. We answer every message. Email us at [email protected].

• 1:00:23Kelly Weinersmith?

  Or you can find us on social media. We have accounts on X, Instagram, Blue Sky, and on all of those platforms, you can find us at D and K Universe.

• 1:00:32Daniel Whiteson?

  Don't be shy. Write to us.

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