Speaker 1: Beetles and fungi are decimating trees in Seattle. Do any
Speaker 1: other invertebrates ride fungi into battle?
Speaker 2: How can the Ambi polar field ignore Earth's magnetic might?
Speaker 2: And why is it stronger on Venus? Could it grow
Speaker 2: here one night?
Speaker 3: Is it true that stress can turn your hair gray?
Speaker 3: My world is kind of a dumpster fire right now,
Speaker 3: so I'd prefer if it didn't.
Speaker 2: Okay, whatever questions keep you up at night, Daniel and
Speaker 2: Kelly's answers will make it all right.
Speaker 1: Welcome to another Daniel and Kelly's Extraordinary Universe, Another Listener
Speaker 1: Questions episode.
Speaker 3: We've done twenty nine of these.
Speaker 2: You know, we haven't actually done twenty nine of these.
Speaker 2: This is the twenty ninth.
Speaker 3: We're doing the twenty ninth of these.
Speaker 2: All right, So my question for you today, County is
Speaker 2: when did you start to go gray?
Speaker 4: Oh?
Speaker 3: Man, gosh, A long time ago.
Speaker 1: I started getting a few random grays towards like the
Speaker 1: end of undergrad, I think, and then in grad school
Speaker 1: it started speeding up. My mom started going gray at eighteen, wow,
Speaker 1: And so I kind of anticipated it would happen, but
Speaker 1: I didn't realize that I was really starting to go
Speaker 1: gray until a friend of mine told me that I
Speaker 1: was quote rocking the salt and pepper look, and I
Speaker 1: gave him the stink eye because I thought of myself
Speaker 1: as someone who had a few stray grays and I hadn't.
Speaker 3: Realized I had transitioned to salt and pepper.
Speaker 1: But it was very nice, and so I anyway, I
Speaker 1: have transitioned to salt and pepper, apparently. And what about you,
Speaker 1: I can't You've got You've got some grays, right, It's
Speaker 1: hard to tell on the riverside camera.
Speaker 2: I think I might have one or two gray beard hairs.
Speaker 3: Daniel. That's not fair, I know.
Speaker 2: But I think I'm still pretty much all original color
Speaker 2: up top.
Speaker 3: So wow, congratulations Daniel.
Speaker 2: Yeah, well, there's some mythology in my family. My grandparents
Speaker 2: on my dad's side both had jet black hair into
Speaker 2: their eighties.
Speaker 3: Wow.
Speaker 2: But there's a discussion in the family about whether or
Speaker 2: not they died it. Oh, And some people are like, oh,
Speaker 2: of course they died it. How naive are you to
Speaker 2: believe that an eighty year old had black hair? And
Speaker 2: I don't know, maybe they did, who knows. I'm not
Speaker 2: going to exhume their body and do.
Speaker 5: Some tests scandalous, but so far.
Speaker 2: In my personal experiment, no, gray's up top.
Speaker 3: Yeah cool. I don't know. I don't really.
Speaker 1: It doesn't keep me up at night that I have
Speaker 1: gray hairs, like you know. I yes, I was a
Speaker 1: little surprised, but mostly it's just because I'm not very
Speaker 1: self aware. But at the end of the day, like
Speaker 1: I don't care enough to diet or anything like that,
Speaker 1: I'm not losing sleep.
Speaker 2: And what comes after salt and pepper, before you're fully
Speaker 2: silver haired? Is there another stage there?
Speaker 3: I don't think so.
Speaker 2: So once you're past salt and pepper, you're just all in.
Speaker 1: I think then you're at silverfox ooh.
Speaker 2: And then you go white and then you're Gandolf. Yeah.
Speaker 3: I look forward to becoming Gandolf. I'll get there. The
Speaker 3: white Wizard.
Speaker 2: Well, that's the thing is people are like, oh, you
Speaker 2: haven't turned gray yet, But I think gray adds gravitas.
Speaker 2: It's nice for people to think you're younger than you are,
Speaker 2: but then it also makes them take you less seriously sometimes. Yeah,
Speaker 2: but something that I do want to take very seriously
Speaker 2: are the questions in the minds of our listeners. Because
Speaker 2: our goal is to give you a tour of everything
Speaker 2: that's extraordinary in the universe, but not just the things
Speaker 2: that we find extraordinary, the mysteries that tackle your minds.
Speaker 2: So if you have questions about how the universe works,
Speaker 2: please write to us two questions at danieland Kelly dot org.
Speaker 2: Today's questions were taken directly from those.
Speaker 1: Messages, and you'll see that Daniel wasn't just gloating at
Speaker 1: the beginning of today's episode, although that might have been
Speaker 1: part of it. We did get a question about graying
Speaker 1: hair towards the end.
Speaker 2: Bumble.
Speaker 3: No, that was just bragging, just straight bragging. There was
Speaker 3: nothing humble in there.
Speaker 1: So all right, so let's move on to question one
Speaker 1: from Eric, and let's go ahead and hear that question.
Speaker 3: Now, hey, they're extraordinaries.
Speaker 1: Eric and I had some technical difficulties, so I'm going
Speaker 1: to go ahead and read his question and rest assured
Speaker 1: the answer has already been shared with Eric. The question
Speaker 1: is regarding the spruce bark beetle in Alaska and their
Speaker 1: relationship with fungus. I understand that they're born with the
Speaker 1: fungus which is parasitic to spruce trees, which knocks back
Speaker 1: the immune response of the trees to resist the beetle.
Speaker 1: The Beatles are a delivery mechanism for the fungus. Is
Speaker 1: this relationship unique to beetles?
Speaker 2: So he spells beatle b e a t l E.
Speaker 2: Is he talking about the insect or the rock band.
Speaker 1: I am going to go ahead and assume that that
Speaker 1: was an auto correct because when I was going ahead
Speaker 1: and taking notes a couple times, my phone and Google
Speaker 1: Docs auto corrected to the band spelling. I guess the
Speaker 1: band is much more popular than the invertebrates.
Speaker 2: Well, but there are more kinds of beatles the invertebrates
Speaker 2: than beatles the singers.
Speaker 1: Right, So yep, yep, many many, Yes, there's I think
Speaker 1: you know, there's probably something like six thousand bark beetles species,
Speaker 1: and there's yeah, far fewer Beatle members.
Speaker 2: And you're not prepared to answer the question if the
Speaker 2: context were rock musicians.
Speaker 3: Yeah, no, that's right.
Speaker 1: Although I did just listen to the Rest is History
Speaker 1: did a few series on the Beatles, but no, I'm
Speaker 1: probably not prepared for a whole Beatles episode.
Speaker 2: All right, So tell us about the bark beetles and
Speaker 2: the relationship with spruce trees.
Speaker 1: Okay, so there's a lot of different species of bark beetles,
Speaker 1: and some of them kill tree and recently there have
Speaker 1: been some mass tree dieoffs as a result of bark beetles.
Speaker 5: They're so sad.
Speaker 1: Yeah, But so you know, a lot of the beetles
Speaker 1: that are causing these die offs are native, which I
Speaker 1: think makes the story a little complicated. So, for example,
Speaker 1: in Alaska, you have this spruce beetle. It's native and
Speaker 1: usually it goes after unhealthy trees, and when its population
Speaker 1: numbers are pretty low, it doesn't cause a lot of trouble,
Speaker 1: Like it takes trees that were already kind of on
Speaker 1: the way out, maybe hastens their demise a bit, but
Speaker 1: that's not a big deal.
Speaker 2: Do you mean it goes after the ones that are unhealthy,
Speaker 2: like it knows or that it just has success against those?
Speaker 3: Oh good question.
Speaker 1: I don't know if it's specifically going after the unhealthy
Speaker 1: ones or if it just is better at the unhealthy ones.
Speaker 1: Because trees do have something like an immune system defense,
Speaker 1: and as we're going to discuss in a moment here,
Speaker 1: the beetles have a fungus that helps them with that
Speaker 1: immune system defense. Amazing, Yeah, but it could be so
Speaker 1: you know, the beatles. I don't think they're like randomly
Speaker 1: blithely going about their life if not making any decisions.
Speaker 1: I think they probably can to some extent tell if
Speaker 1: they are near a tree that is going to be
Speaker 1: easier or less easy to invade, And so probably they're
Speaker 1: they're searching for the unhealthy ones that they'll have an
Speaker 1: easier chance with. But at high population numbers, though, some
Speaker 1: of those unhealthy ones might get crowded and they get
Speaker 1: pushed out to healthy ones. Let's say that's what's happening, right,
Speaker 1: And so when they get to really high population densities
Speaker 1: and there's loads of these beetles all over the place,
Speaker 1: they start killing the healthy trees too.
Speaker 3: And so, for example, there's been.
Speaker 1: An outbreak of these beetles in Alaska and something like
Speaker 1: one point six million acres have been impacted, and that
Speaker 1: means a bunch of yeah, many, many, many of these
Speaker 1: native trees, native spruce trees have been killed in Alaska.
Speaker 1: And there's another outbreak of the Eurasian spruce bark beetle
Speaker 1: that's happening right now in Europe and it's decimating the
Speaker 1: conifer forests. And so you know, as I mentioned, a
Speaker 1: lot of these beetles are native, and so the question is,
Speaker 1: you know, like I think a lot of us are
Speaker 1: bummed out because we like forests.
Speaker 5: And we like trees and living trees.
Speaker 1: Living trees, right, and the idea that beetles are killing
Speaker 1: a bunch of trees stinks. But I guess the question
Speaker 1: is is this a natural process or not? So, you know,
Speaker 1: when a bunch of trees die, they fall, and that
Speaker 1: clears forest floor to suddenly get sunlight that wasn't getting
Speaker 1: sunlight before because the trees were blocking it.
Speaker 3: And now you can.
Speaker 1: Get flowers and pollinators, and this is sort of how
Speaker 1: ecosystems turn over. Ecosystems are not usually stagnant, and so
Speaker 1: I guess the interesting question to me is is this
Speaker 1: like a two hundred year cycle and we just kind
Speaker 1: of weren't taking notes before and we're just seeing something
Speaker 1: that naturally would have happened. Or would the two hundred
Speaker 1: year cycle have included maybe like one hectare of trees
Speaker 1: dying but because of global climate change or because we've
Speaker 1: managed forests in a way that you know has made
Speaker 1: more trees unhealthy, is it just way more intense than
Speaker 1: it's ever in the past, in which case, you know,
Speaker 1: maybe we care now because we have made this problem
Speaker 1: much worse than it would have been.
Speaker 2: Does that make sense, Yeah, But I had the impression
Speaker 2: that some forests were truly ancient. You know that forests
Speaker 2: can be fairly stable. If the climate is stable, et cetera,
Speaker 2: then trees can grow for hundreds or thousands of years.
Speaker 2: So it's not like there's a two hundred year cycle
Speaker 2: where all the trees in the forest die and then
Speaker 2: get replaced. And that's just what we're seeing, right. It
Speaker 2: feels like we're seeing a shift in the capacity for
Speaker 2: forests to exist. Right out here in the West, we
Speaker 2: see lots and lots of dead trees on hillsides, and
Speaker 2: it feels like, maybe you we're seeing the ends of forests.
Speaker 1: Well, so, first of all, when I said two hundred,
Speaker 1: I probably should have said x because I was just
Speaker 1: picking a number. But so I was listening to Indefensive Plants,
Speaker 1: which is a great plant podcast, and they had a
Speaker 1: guy on there who studies bark beetles, and he was
Speaker 1: saying that, like, you know, we really don't know if
Speaker 1: this is a natural cycle or if it's something that's
Speaker 1: getting much worse and we do think that probably it
Speaker 1: is a problem that has gotten much worse. But for
Speaker 1: a lot of the stuff, we don't have great data. Yeah,
Speaker 1: because if X is a thousand and it's like a
Speaker 1: thousand year cycle, we probably wouldn't have great data on that.
Speaker 1: Maybe every one thousand years, you do expect to see
Speaker 1: all the trees on the hillside's dead and then the
Speaker 1: cycle starts again or something. But it wouldn't surprise me
Speaker 1: to hear that we have made this problem worse through
Speaker 1: global climate change and exacerbating drought and stuff like that.
Speaker 1: But let's get back to the beetles in the fungus.
Speaker 2: Yeah, so what are the beatles doing to the trees
Speaker 2: and how does the fungus help?
Speaker 1: Okay, so the beatles arrive at a tree and they
Speaker 1: like you know, for example, they might go under the
Speaker 1: bark and the adults might move around under the bark.
Speaker 1: And when they do that, they introduce a fungus. And
Speaker 1: this fungus the only way it can get from like
Speaker 1: tree to tree is it travels with the beetles, and
Speaker 1: so that's how the beetles benefit the fungus.
Speaker 3: So then the fungus.
Speaker 1: Infects the tree and it does a couple different things
Speaker 1: for the beetles. One of the things that it does
Speaker 1: is that the tree has a bunch of chemical defenses
Speaker 1: that it would use to make the beetles sick and
Speaker 1: kill them. And the fungus takes those chemicals that the
Speaker 1: tree was using to defend itself and it neutralizes those chemicals,
Speaker 1: so the tree is no longer toxic.
Speaker 3: To the beetles. Amazing, totally agree. Yeah, it's crazy.
Speaker 1: And now instead the beetle is starting to convert stuff
Speaker 1: in the tree to stuff that's nutritious for the beetles.
Speaker 1: So now it's easier for the beetles to get nutrition
Speaker 1: from the tree. The beetles aren't getting attacked by the tree.
Speaker 1: In some cases, the beetles are actually converting some of
Speaker 1: the things that the tree makes into pheromones to attract
Speaker 1: more beetles to the tree. Wow, I know, it's crazy.
Speaker 1: And so then the beetles lay their eggs in the tree.
Speaker 1: And you know, if you've worked with like trees before,
Speaker 1: maybe sometimes you've pulled a piece of bark off and
Speaker 1: underneath you've seen all of these sort of like almost
Speaker 1: random lines that chriss cross over each other. Those are
Speaker 1: the paths of like little baby beetles that have hatched
Speaker 1: and sort of moved around, and it's like the path
Speaker 1: of the food that they ate and the movements that
Speaker 1: they made.
Speaker 2: Yeah, like these little tunnels that they've dug through underneath
Speaker 2: the bark. Yeah, it's very cool to see.
Speaker 1: Yeah, they're called galleries, and I do feel like they're
Speaker 1: little works of art, Like I love that name for them.
Speaker 1: And so anyway, this reproduction keeps happening, and with this
Speaker 1: collaboration between the beetle and the fungus, the beetles are
Speaker 1: able to overwhelm the tree's defenses and they can kill
Speaker 1: the tree that way.
Speaker 2: And is this something that happens to trees worldwide? This
Speaker 2: must be a common pattern between beetles and trees. I
Speaker 2: remember seeing these kinds of patterns on the back of
Speaker 2: bark of like Ponderosa pines in New Mexico, for example.
Speaker 1: Yeah, so lots of trees have bark beetles, like at
Speaker 1: least one bark beetles species. Sometimes you can find more
Speaker 1: than one beetle species living in different parts of trees.
Speaker 3: Not all of them are super bad for the tree.
Speaker 1: And again, a lot of times it depends on how
Speaker 1: many beetles there are, how bad the condition of the
Speaker 1: tree is. But yeah, you can find these almost all
Speaker 1: over the world. It seems to particularly be a problem
Speaker 1: for like spruces and pines and stuff.
Speaker 2: Is it ever good for the tree? Are they doing
Speaker 2: anything that's helpful.
Speaker 1: I didn't come across examples of that in my reading.
Speaker 1: Oh yeah, it doesn't mean it's not out there. I
Speaker 1: didn't read every paper on bark beetles, as you can imagine,
Speaker 1: with over six thousand species, there's a lot of papers
Speaker 1: out there.
Speaker 2: Well, I don't know why, but I feel my self
Speaker 2: rooting for the trees. I mean, I'm not the lorax
Speaker 2: or anything, and beetles have just as much a right
Speaker 2: to live and to eat as trees do. But it
Speaker 2: feels like, you know, the trees have this grandeur and
Speaker 2: they're supposed to be there, and the beetles are invading whatever.
Speaker 2: So give me a more ecological viewpoint on this. Why
Speaker 2: should I not be attached to the trees or should I?
Speaker 1: Yeah, I think you could argue either way. Like, I mean,
Speaker 1: I'm attached to the trees, and when the trees die,
Speaker 1: then the like you know, the woodpeckers that we're living
Speaker 1: in there, don't have a home anymore, and like all
Speaker 1: of the other organisms that depended on those trees are
Speaker 1: in trouble. Yeah, you know, I think it makes sense
Speaker 1: that we get sort of emotionally attached to those forests
Speaker 1: and all the organisms that live in there. But you know,
Speaker 1: the only constant and life is change, and ecosystems do
Speaker 1: pretty regularly turn from one thing to another, and so
Speaker 1: you know, expecting a system to stay exactly the same
Speaker 1: can cause problems. So, like one problem that humans have
Speaker 1: caused is we've tried to suppress fires because we thought, well,
Speaker 1: fires are bad, but now we've let fuels build up
Speaker 1: over time, and now there's tons of fuel and so
Speaker 1: when you do get a fire, it burns extra super
Speaker 1: hot and it kills everything, whereas before there were some
Speaker 1: species that would have survived a fire that didn't burn
Speaker 1: quite as hot. And so, you know, we kind of
Speaker 1: mess things up when we tinker with it. So the
Speaker 1: question is should we tinker with this spark beetle situation?
Speaker 1: And can we tinker with this bark beetle situation? Like
Speaker 1: what could you even do? They're living under the bark,
Speaker 1: and like, you know, what can you do that would
Speaker 1: target the beetles or their fungus without messing with the
Speaker 1: rest of the ecosystem.
Speaker 3: Like, it's a really tough problem.
Speaker 1: And I don't want to make it sound like I'm
Speaker 1: saying we should throw up our arms and not do
Speaker 1: anything ever, but just that, you know, these are complicated
Speaker 1: problems that you need to think about from multiple angles.
Speaker 2: Yeah, And I definitely have emotional connections to some parts
Speaker 2: of the ecosystem, you know, like anything that threatens my
Speaker 2: children for example. Oh yeah, you know, I'm not just
Speaker 2: going to be like that it's in the way of
Speaker 2: coyotes to tear out the throats of my children. Like,
Speaker 2: you know, I'm definitely stepping in there and doing something wild.
Speaker 1: Note that that one. We got an email from PETA
Speaker 1: encouraging us to think about things from the animal standpoint.
Speaker 1: A while back, and when I moved out to the
Speaker 1: middle of nowhere, I did do a lot of research
Speaker 1: on whether or not it was safe to let my
Speaker 1: like three year olds outside with coyotes. I was outside
Speaker 1: with my three year olds, and it is very rare
Speaker 1: for a coyote to go after a three year old.
Speaker 1: But you are encouraged to stay with your three year
Speaker 1: olds outside if there's coyotes around. But once they get bigger,
Speaker 1: the coyotes are very unlikely to go after them. So
Speaker 1: your children are safe from coyotes at this age, I
Speaker 1: would suspect.
Speaker 2: I hope that's true. Just two days ago, my daughter
Speaker 2: called me because she was out walking our dog and
Speaker 2: there was a coyote that blocked her on a path
Speaker 2: and she was like, I don't know what to do.
Speaker 2: So I biked over there and made my presence known.
Speaker 1: Oh wait, and so you had to scare the coyote away? Yeah,
Speaker 1: oh wow.
Speaker 2: Yeah. They are very brazen in our neighborhood now. They
Speaker 2: roam in packs, they're everywhere, and hey, you know, we
Speaker 2: moved into their neighborhood. So on the other hand, I
Speaker 2: don't really want them eating my kids or my dog.
Speaker 3: Yeah.
Speaker 2: But back to the question at hand, we're talking about
Speaker 2: fungi and beetles. One question I had is these beetles
Speaker 2: are using the fungus to help colonize the tree. What's
Speaker 2: in it for the fungus and what's happening when the
Speaker 2: beetles are not in a tree, or are the beetles
Speaker 2: never not in a tree?
Speaker 1: The beetles are pretty much always in a tree or
Speaker 1: moving from one tree to another, and the fungus get transport.
Speaker 1: So the best way for the fungus to get from
Speaker 1: one tree to another is by being moved by the fungus.
Speaker 1: That's the main thing we think that they get from it.
Speaker 2: Okay, and are beetles the only ones who do this
Speaker 2: kind of fungus farming?
Speaker 3: No?
Speaker 5: Really?
Speaker 1: Yeah, So Eric wanted to know, you know what other
Speaker 1: invertebrates collaborate with fungi, And it turns out that there's
Speaker 1: quite a few invertebrates that collaborate with fungus, and so
Speaker 1: fungus farming is a pretty common thing in the invertebrate world. Daniel,
Speaker 1: I have a question for you termites. You look at termites,
Speaker 1: what do you think termites are closely related to If.
Speaker 5: You had to guess, hmmm, termite.
Speaker 3: Or do you already know the answer to this?
Speaker 2: I do not know the answer. Okay, they're an insect
Speaker 2: because of the legs they got all those little segments,
Speaker 2: they seem kind of antie to me, thank you.
Speaker 3: Yes, they do look anti to me.
Speaker 1: And so I said something to one of my friends
Speaker 1: about them being, you know, kind of ant like, and
Speaker 1: they were like, Kelly, they're more closely related to cockroaches what.
Speaker 1: And I looked at them for a second and I
Speaker 1: kind of gave them a little bit of the stink
Speaker 1: guy because I was like, you are either messing with
Speaker 1: me or I should be very embarrassed because I.
Speaker 3: Am way off here. And it turned out I was
Speaker 3: way off.
Speaker 2: Well, I don't have to be embarrassed because I'm not
Speaker 2: supposed to know so well.
Speaker 1: Yeah, and I wasn't trying to embarrass you like you
Speaker 1: were trying to embarrass me about my gray hair earlier.
Speaker 2: But ooh, life, I'm impressed by the gravitas your gray
Speaker 2: hair lends to you.
Speaker 1: Oh thank you. Yes, I looked very mature and commanding
Speaker 1: of wisdom and whatnot. Exactly all right. So, fungus farming
Speaker 1: is seen in some termites, ants, wood wasps, and ambrosia beetles.
Speaker 1: So basically the deal here is that they collect certain
Speaker 1: kinds of fungus. They put fungus in a certain area. Sometimes,
Speaker 1: for example, there are like leafcutter ants who will feed
Speaker 1: the fungus certain kinds of leaves, and then the fungus
Speaker 1: will break it down into things that are more digestible
Speaker 1: for you know, for example, the leaf cutter ants. So
Speaker 1: let's talk about the Ambrosia beetles for a second. So
Speaker 1: the Ambrosia beetles will farm fungus and they will bring
Speaker 1: them into for example, like dead trees, and then they'll
Speaker 1: create those galleries that we were talking about, and they'll
Speaker 1: sort of lay their eggs, they'll have their babies, and
Speaker 1: the fungus will be like creating food for everybody. And
Speaker 1: the Ambrosia beetles even have little specialized parts on their
Speaker 1: body so that they can carry the fungus with them
Speaker 1: from one place to another. And so this is like
Speaker 1: a very close symbiosis, so they can, you know, can
Speaker 1: bring it from one place to another. But while I
Speaker 1: was reading about this, I discovered a cool concept called micocleptism.
Speaker 1: And so while some Ambrosia beetles will bring the fungus
Speaker 1: with them from place to place and will essentially live
Speaker 1: with the same strains of fungus for their whole lives,
Speaker 1: other beetles will steal fungus from others. And so there
Speaker 1: are some beetle species who will find an Ambrosia beetle
Speaker 1: who's doing a good job of farming their own fungus.
Speaker 1: They're being good farmers, good stewards of the land, and
Speaker 1: then the micocleptics will will come in and they'll steal
Speaker 1: some of the fungus and they'll start farming it on
Speaker 1: a different part of the log, kind of close by.
Speaker 1: They'll lay their own eggs in there, and they'll essentially
Speaker 1: steal the fungus. And so they don't they're not born
Speaker 1: with this fungus. They take it from another organism over
Speaker 1: the course of their lives.
Speaker 2: Wow, that's a little creepy.
Speaker 3: It's a little creepy.
Speaker 1: Yeah, yeah, it it'd be like your family stealing beans
Speaker 1: from another family or something, you know, because you guys
Speaker 1: have a close symbiosis with beans and chia seeds.
Speaker 2: That's true, we do. We are lovers of fermented foods
Speaker 2: and fiber. Over here. Mm hmm, Okay, we're back and
Speaker 2: we're answering questions from listeners today. Questions about Beatles, questions
Speaker 2: about space, questions about what's going on on Kelly's cranium.
Speaker 1: On my cranium. How did we get to talking about
Speaker 1: my cranium?
Speaker 2: Are we going to be talking about gray hair, salt
Speaker 2: and pepper silver foxes later?
Speaker 1: Oh yeah, okay, we're back. We're back to my gray hair,
Speaker 1: so we're going to talk about my crow's feet too.
Speaker 1: Is there anything else you want to point out that's
Speaker 1: wrong with me?
Speaker 3: Daniel?
Speaker 2: I never noticed any crows feed, Kelly. This is the
Speaker 2: first I hear about them.
Speaker 3: No, no, you're not.
Speaker 1: You can't walk back the problem you started earlier today, Daniel.
Speaker 1: All right, let's change the subject and hear what Gene
Speaker 1: has to say.
Speaker 6: Hi there, Daniel and Kelly. I've recently heard about the
Speaker 6: Ambi polar field and I'm fascinated to know more. It
Speaker 6: seems to be independent of the earth magnetic field, but
Speaker 6: I don't understand how that can be. Can you explain.
Speaker 6: I've also heard that the field is much stronger on Venus,
Speaker 6: and that's one reason why Venus no longer has oxygen
Speaker 6: or hydrogen in its atmosphere. But why is it stronger
Speaker 6: on Venus than on Earth? And was it always that strong?
Speaker 6: If not, might it increase on Earth. I'm loving the
Speaker 6: show and being able to ask questions. It's like having
Speaker 6: a tame professor in the spare room. So I'm really
Speaker 6: looking forward to hearing your answers to my questions. Thank you.
Speaker 2: All right, So Gene has a really fun question about
Speaker 2: electric and meg magnetic fields around the Earth. And this
Speaker 2: is a field I think a lot of people haven't
Speaker 2: heard of.
Speaker 1: Yeah, I don't think that I've heard, or if I have,
Speaker 1: I've forgotten about the ambu polar field. Right, So I'm
Speaker 1: thinking about ambidextrous and you can switch between left and right.
Speaker 1: Is that Is that helping me understand ambipolar because it can?
Speaker 3: It's okay.
Speaker 2: So most people are familiar with Earth's gravitational field right.
Speaker 2: In a Newtonian picture, gravity is a force and it
Speaker 2: polls on stuff, and things with more masks get pulled
Speaker 2: on more strongly, and that's what holds the atmosphere in place,
Speaker 2: for example, or Earth's magnetic field. Magnetic fields are generated
Speaker 2: by charges in motion, So like currents of magma and
Speaker 2: other metals inside the Earth we think generate the magnetic
Speaker 2: field not fully understood with all sorts of weird behavior
Speaker 2: like the poles move and the poles flip, all this
Speaker 2: kind of stuff. The ambipolar field is something completely separate
Speaker 2: from both of those. It's a totally separate effect coming
Speaker 2: from atoms in the app hemosphere being ionized.
Speaker 3: Ah All right, So.
Speaker 1: Is this going to have anything to do with the
Speaker 1: Aurora borealis.
Speaker 2: Not directly, no, but a little bit, yeah, a little bit.
Speaker 2: So what happens is if you have a neutral particle,
Speaker 2: like if a proton and an electron they're bound together,
Speaker 2: they make hydrogen for example, everything is happy, but sometimes
Speaker 2: things get hot and electrons leave their protons, and now
Speaker 2: you have ions protons that are positively charged and electrons
Speaker 2: electrons are negatively charged, and they're separated. So this is
Speaker 2: like a plasma. And in the upper atmosphere you have
Speaker 2: high speeds and not everything is bound together. So there's
Speaker 2: lots of protons and electrons up there, not just all
Speaker 2: neutral atoms. So now you have the gravitational force. It's
Speaker 2: going to pull harder on the protons than it is
Speaker 2: on the electrons. Why because protons are much more massive
Speaker 2: than the electrons.
Speaker 5: M hm, I remember that, mm hm.
Speaker 2: And so what that means is that protons are lower
Speaker 2: in the atmosphere than electrons. You get this because the
Speaker 2: electrons are lower mass, they're moving faster with the same
Speaker 2: kinetic energy. So essentially you get an imbalance. Right now,
Speaker 2: you have the electrons higher up than the protons. That
Speaker 2: creates an electric field because you have these charged particles,
Speaker 2: and when you create a separation of charges, you get
Speaker 2: a field between them because essentially there's a force that
Speaker 2: wants to pull them back. That is an electric field.
Speaker 2: The Ambi polar field in the upper atmosphere of Earth
Speaker 2: and also Mars and also Venus. So that's what the
Speaker 2: Ambi polar field is.
Speaker 3: WHOA Okay, all right? So first of all, can you
Speaker 3: use that for anything?
Speaker 2: You can use it to create like a gun of
Speaker 2: particles out into space. So for example, this field will
Speaker 2: pull on particles, it'll pull protons up, and in some
Speaker 2: parts of the Earth it'll create like a polar fountain,
Speaker 2: and like at the North Pole it creates like a
Speaker 2: font of hydrogen atoms, hydrogen ions actually shooting up and
Speaker 2: out of the Earth. I don't know if that's useful
Speaker 2: for anything, but.
Speaker 3: It's kind of okay, yep needs And you could also.
Speaker 2: In principle use it to help like steer satellites. You know,
Speaker 2: there's one way to steer satellites instead of having thrusters.
Speaker 2: You used to like use the Earth's electric and magnetic fields.
Speaker 2: Like you have a long tether and you twist it
Speaker 2: and that creates torque or you can use it to
Speaker 2: create thrust. It's fairly weak though, so not like big
Speaker 2: satellites or anything. But you know, it adds to this
Speaker 2: sort of texture of the near Earth environment.
Speaker 1: Okay, awesome, And then okay, so you so Earth, Mars,
Speaker 1: and Venus have it all, right, So what are they are?
Speaker 1: So they all have gravity, but every planet has gravity.
Speaker 1: They all have atmospheres, So you need an atmosphere.
Speaker 2: Although Mars's atmosphere is much much weaker, so its ambipolar
Speaker 2: field is also weaker.
Speaker 3: Yeah, and Mars is like what one percent of Earth's
Speaker 3: or something.
Speaker 2: Yeah, exactly.
Speaker 1: Is that all you need is a gravitational field and
Speaker 1: an atmosphere to have an ambipolar field.
Speaker 2: That's almost all you need. You need ions in your
Speaker 2: atmosphere also, right, If it's all neutral particles, you're not
Speaker 2: going to get an ambipolar field. And that's one reason
Speaker 2: why Venus has a much stronger ambipolar field than Earth
Speaker 2: Number one has a very dense atmosphere, so there's a
Speaker 2: lot of electrons and ions to pull apart. But also
Speaker 2: because Venus has no magnetic field, it has no protection
Speaker 2: from the solar wind. See we're going to get to
Speaker 2: the Aurora Borealis connection, and the solar wind is what
Speaker 2: creates a lot of these ions in the upper atmosphere.
Speaker 2: So you have energy from space photons and protons, etc.
Speaker 2: Hitting the upper atmosphere that ionizes it. That energy from
Speaker 2: space breaks open neutral atoms to create your ion and
Speaker 2: your electron. And because Venus doesn't have a magnetic field
Speaker 2: to protect it from the solar wind, a lot of
Speaker 2: that solar radiation causes more ionization and speeds up those
Speaker 2: particles because all this energy is coming from space, and
Speaker 2: so that gives you a lot of ions, and those
Speaker 2: ions are now moving fast, and so that helps these
Speaker 2: ions escape. So that creates a very strong ambipolar field
Speaker 2: on Venus. And this is always sort of counterintuitive, like
Speaker 2: the electrons get high high, the protons get lower, and
Speaker 2: so that's the amberpolar field. But then the effect on
Speaker 2: the other particles is the opposite. That field is always
Speaker 2: trying to cancel itself out. Electromagnetism is always doing whatever
Speaker 2: it can to cancel itself out because it's so strong.
Speaker 2: So you create that field by separating them. Then the
Speaker 2: field has the effect of pushing the ions up and
Speaker 2: the electrons down. Which is why you get this like
Speaker 2: font of hydrogen ions. In a similar way sort of
Speaker 2: that if you immerse a metal in an electric field,
Speaker 2: the electrons in that metal will move to counter that
Speaker 2: electric field because the electric field has pushed on those electrons. Right,
Speaker 2: So electromagnetism is always doing everything it can to zero
Speaker 2: itself out. Doesn't want to ever do anything. It's just
Speaker 2: so lazy.
Speaker 1: Okay, So it's stronger on Venus. So is it stronger
Speaker 1: on Venus for two reasons? One Venus has a thicker
Speaker 1: atmosphere and two you're more likely to have charged particles
Speaker 1: in that atmosphere.
Speaker 2: Yes, exactly. So it's not directly connected to the magnetic field.
Speaker 2: It's not caused by the magnetic field in that sense.
Speaker 2: I think that was Jane's question. But it is indirectly
Speaker 2: connected because the magnetic field will help you prevent ionization
Speaker 2: of your upper atmosphere, which would reduce the amber polar field.
Speaker 2: And so Venus has a strong one because two reasons, Yes,
Speaker 2: has a denser atmosphere and it doesn't have protection from
Speaker 2: the solar radiation. Now, we think that a long time
Speaker 2: ago Venus was a very different situation. It might have
Speaker 2: had a magnetic field before its internal bits seized up
Speaker 2: and it cooled. It might have had internal motion which
Speaker 2: generated a magnetic field which shielded it from some solar radiation,
Speaker 2: which would have had less ionization. Now it's lost on
Speaker 2: magnetic field, so it gets more radiation and a stronger.
Speaker 1: Field cool Okay, Now, could Earth get a stronger ambipolar field.
Speaker 2: Yes, it's possible that our ambipolar field could increase, but
Speaker 2: for that to happen, we'd essentially have to lose our
Speaker 2: magnetic field. We have to be more susceptible solar radiation,
Speaker 2: so that could either be we lose our magnetic field,
Speaker 2: which seems unlikely. I mean, we don't really understand it,
Speaker 2: and it's been kind of flip flopping and slashing around.
Speaker 2: But total loss of the magnetic field would require the
Speaker 2: Earth's internal mechanisms to seize up the way Mars has
Speaker 2: and Venus has, and that seems unlikely it happens soon
Speaker 2: because there's still plenty of activity going on insider. If
Speaker 2: it would happen, it would be slow and gradual. Or
Speaker 2: the other thing is we could have more solar radiation,
Speaker 2: so we could get more ionization, and that's more unpredictable
Speaker 2: like that just depends on Hey, is the Sun gonna
Speaker 2: burbt us some huge blob of plasma that comes and
Speaker 2: strips away a lot of the atmosphere or ionizes it.
Speaker 2: That could happen in any moment. You know, just a
Speaker 2: few weeks ago we had really strong aurora boreality is
Speaker 2: how you pluralize it. You could see them pretty far
Speaker 2: south in the United States because of the space weather
Speaker 2: event from the Sun, and that comes from not understanding
Speaker 2: the internal dynamics and the chaos of the Sun's plasma
Speaker 2: well enough to So, yeah, we could get a stronger
Speaker 2: ambipolar field if we got more solar radiation or if
Speaker 2: we weakened our protection from it. Either one would give
Speaker 2: us more ions and therefore a stronger ambipolar field.
Speaker 1: Neither one of those options sound great for the humans
Speaker 1: living here, So let's hope it doesn't happen.
Speaker 2: All right, Well, let's send that answer to Jane and
Speaker 2: hear if it freaked her out or made her feel
Speaker 2: more at one with her understanding.
Speaker 5: Of the universe.
Speaker 3: And let's hear if she's going to kick the professor
Speaker 3: out of her spare room.
Speaker 4: Thank you so much for your answer, Daniel, I really
Speaker 4: feel I understand the ambipolar field now, and I'm very
Speaker 4: relieved the way for the most part, protected from Venus's
Speaker 4: fate by our wonderful magnetic field. But I do love
Speaker 4: the idea of a polar fountain. Sounds like something Santa
Speaker 4: would have. Oh, by the way, my spare room is
Speaker 4: still available for professors if you're ever in the North
Speaker 4: of England. Thanks for a great.
Speaker 1: I don't know, Daniel, if you had a professor in
Speaker 1: your spare room for questions, would you want a physicist
Speaker 1: or maybe a less smelly profession.
Speaker 2: We often have a professor in our spare room because
Speaker 2: we have a guest room and people come to visit
Speaker 2: and sometimes, you know, you invite a friend to come
Speaker 2: and visit for official reasons to give a talk, but
Speaker 2: then you also want to hang out with them and
Speaker 2: you don't want to put them up in a hotel,
Speaker 2: so they sleep in our spare room and have dinner
Speaker 2: with us, and that's a lot of fun. So often
Speaker 2: we have biologists and physicists or physicists usually coming to
Speaker 2: stay with us, and our kids have expressed their lack
Speaker 2: of enthusiasm for physics or biology dominated dinner conversations.
Speaker 1: Our kids at some point asked us to please stop
Speaker 1: talking about space law over dinner.
Speaker 3: H Yeah, I understand. All right. Let's move on to
Speaker 3: our question from Joe.
Speaker 7: Hi, Danielle, and Kelly. I've often heard the claim that
Speaker 7: stress made me get all these great hairs? Is there
Speaker 7: any biological validity to that concept? And if so, what
Speaker 7: are the mechanisms? Can your emotional state plus cortisol or
Speaker 7: dopamine levels perhaps affect this part of your biology? Finally,
Speaker 7: has it been observed in any other animals? Thanks so
Speaker 7: much for bringing some color or salt and pepper to
Speaker 7: this question.
Speaker 2: All right, So Joe suggested, the gray hair isn't just
Speaker 2: about age. It might be about stress. It's about like
Speaker 2: emotional age, not you know, cosmological age.
Speaker 1: That's right, and so I think it's possible that there
Speaker 1: are different mechanisms at play here. So let's go ahead
Speaker 1: and leave my old age related grays to the side.
Speaker 1: We don't have to talk about them anymore. Actually, okay,
Speaker 1: all right, and so to understand what's happening, let's go
Speaker 1: ahead and talk about the hair cycle. All right, So
Speaker 1: you have loads of hair follicles on your head?
Speaker 2: I do you do you do one does.
Speaker 1: Not only is your hair not gray, but you actually
Speaker 1: have it covering your whole head. You are very lucky
Speaker 1: for a fifty year old. Or are we rounding up
Speaker 1: to one hundred?
Speaker 5: Now?
Speaker 2: Yeah, exactly, I'm more than fifty, so rounds up.
Speaker 3: Okay, all right.
Speaker 1: So each of our hair follicles goes through a cycle,
Speaker 1: and our hair follicles aren't SYNCD, so our hair follicles
Speaker 1: tend to be at different stages of this cycle. Anigen
Speaker 1: is the part of the cycle where your hair is growing,
Speaker 1: and for the hair on top of your head, the
Speaker 1: stage usually lasts about four to six years.
Speaker 5: Oh that's all yeah, yeah.
Speaker 1: Kind of surprising, right, and your hair is growing something
Speaker 1: like half an inch a year. And early in anigen,
Speaker 1: what happens is that you have hair follicle stem cells,
Speaker 1: and so stem cells our cells that are they're like
Speaker 1: they're like baby stem cells.
Speaker 3: There's things that they can become, but they haven't.
Speaker 1: Become them yet. And these are cells that are going
Speaker 1: to become hair follicles, but they haven't become them yet.
Speaker 1: So they're hanging out there and when the time comes,
Speaker 1: they will become hair follicles and they're just waiting for
Speaker 1: the message.
Speaker 3: When you get to this.
Speaker 1: Early growth phase, these hairfollical stem cells jump into action.
Speaker 1: They make a hair follicle, and now you've got your
Speaker 1: hair follicle.
Speaker 2: All right. So I have stem cells on my scalp
Speaker 2: my whole life, waiting to become follicles. Mm hm, cool,
Speaker 2: didn't know that.
Speaker 1: And you also have melanocytes stem cells, and so what
Speaker 1: they're doing is they're waiting to produce melanocytes. And these
Speaker 1: are the cells that make melanin, which is the pigment
Speaker 1: that gives hair color. And so early in anigen, your
Speaker 1: hair follicle is being made, and your melanocyte stem cells
Speaker 1: are activated to make melanocytes, and the melanocytes will travel
Speaker 1: down to your hair follicle and they get ready to
Speaker 1: start making melanin. So now your hair follicle is making
Speaker 1: the hair, your melanocytes are making the melanin, and now
Speaker 1: you have hair that has color.
Speaker 2: And all of my melaninites have to all be coordinated, right,
Speaker 2: because I have like one color of hair on my head,
Speaker 2: and do you have a different color of hair? And
Speaker 2: my daughter's blonde, for example, And so there's a genetic
Speaker 2: coating in there. That controls all of the melaninites or
Speaker 2: melanocytes melanocytes.
Speaker 3: Yes, they're all making the same color.
Speaker 5: I see. Yeah, Okay.
Speaker 2: So the thing that's confusing to me is if they
Speaker 2: only last for four to sixty years, how come I
Speaker 2: didn't lose all my hair when I was seven?
Speaker 3: Because there's a cycle.
Speaker 1: Okay, So you've got four to six years, and then
Speaker 1: you go into a phase called the catagen phase where
Speaker 1: everything sort of degenerates. You lose the blood vessels and
Speaker 1: so now the hair follicle isn't getting oxygen or nutrients,
Speaker 1: and this lasts about two weeks. And at this stage
Speaker 1: the melanocytes die, but your melanocytes stem cells are still alive,
Speaker 1: so you still have cells that can make more melanocytes,
Speaker 1: but the melanocytes that were made a few years ago
Speaker 1: they're toast.
Speaker 5: Okay, okay.
Speaker 1: And then you go into a resting phase and this
Speaker 1: can last for a few months where the hair follicles
Speaker 1: just kind of chilling out, and then you go into
Speaker 1: a phase called exigen where the original hair is shed
Speaker 1: out because you've started the cycle again. A new hair
Speaker 1: is growing and it pushes out the old one you shed,
Speaker 1: So you shed something like fifty to one hundred hairs
Speaker 1: a day, and so that's how many hairs are sort
Speaker 1: of beginning the process anew. And when you start that
Speaker 1: process ANEW, those two types of stem cells wake up again.
Speaker 1: They start doing their jobs again. And after the new
Speaker 1: hair follicle has started and after the new melanocytes are
Speaker 1: have gone to work, those two sets of stem cells
Speaker 1: go to sleep again for like, you know, four to
Speaker 1: six years or whatever. They do their job, they make
Speaker 1: the cells that are going to work through the cycle,
Speaker 1: and then the stem cells go to sleep.
Speaker 3: Does that make sense.
Speaker 2: That makes a lot of sense, and it really helps
Speaker 2: me understand something I remember wondering about when I was
Speaker 2: like a teenager young physicist. Daniel was thinking about hair
Speaker 2: growth the way you think about like radioactive decay. You know.
Speaker 2: I was thinking maybe it was like probabilistic and hairs
Speaker 2: would just like fall out randomly. But if that were
Speaker 2: the case, you'd start with like a full head of
Speaker 2: hair and then you just gradually lose hairs until eventually
Speaker 2: you had like one super long hair, which would be
Speaker 2: you had. Clearly, that model does not explain the data,
Speaker 2: So I like your model a lot better.
Speaker 1: Oh good, Okay, well, and there's a lot of variability.
Speaker 1: Some people have you know, shorter cycles, so their hair
Speaker 1: doesn't grow as long, right, and the cycle on your
Speaker 1: body as much shorter, so your body hairs never get
Speaker 1: as long as the hair is on your head. But
Speaker 1: this is like sort of generally or understanding of how
Speaker 1: the cycle goes on average.
Speaker 2: All right, And so there's really two different bits there.
Speaker 2: There's like the hair growing and the hair coloring, and
Speaker 2: so tell us about why the hair coloring can go
Speaker 2: wrong or why things turn gray?
Speaker 3: All right?
Speaker 1: So I found this amazing paper jang at All twenty
Speaker 1: twenty in Nature did this amazing set of bar ORMs
Speaker 1: that sort of like deal with tons of different hypotheses,
Speaker 1: and they really nail it down in mice.
Speaker 3: So again this is in mice. Keep in mind it's
Speaker 3: in mice, not in humans.
Speaker 1: But okay, so first they say if you stress out
Speaker 1: black mice, will they get gray hairs? So they stress
Speaker 1: mice out a couple different ways, and the mice do
Speaker 1: start going gray.
Speaker 2: Are they terrible?
Speaker 1: Uh No, I mean they're not. They're not the worst
Speaker 1: I've read about.
Speaker 2: I have to imagine how I stress out a mouse.
Speaker 2: I might like put it in a cage next to
Speaker 2: a cat, not to kill it, but just to like
Speaker 2: put it in the cage next to it. That would
Speaker 2: be pretty stressful for a mouse.
Speaker 3: Oh okay, So no, this is nowhere near that bad. Actually.
Speaker 1: So they would rapidly change the light and dark cycles.
Speaker 1: They would leave the bedding be a little bit damp,
Speaker 1: they would have the cage be sort of tilted. They
Speaker 1: leave them in a cage by themselves, and they're kind
Speaker 1: of in a social species. So nowhere near as bad
Speaker 1: as what you're thinking.
Speaker 2: That's very gentle, Yes, that is yes.
Speaker 3: Yeah.
Speaker 1: And again, as we've discussed multiple times on the show,
Speaker 1: before you do experiments like this, you need to get
Speaker 1: animal care and use protocols. And we understand you have
Speaker 1: to stress the animals out to test the hypothesis, but
Speaker 1: you've got to.
Speaker 3: Do it in the most human way possible.
Speaker 1: Good okay, But the most effective and fast method they
Speaker 1: found for stressing the animals out was to give them
Speaker 1: an injection of a capsayasin analog under their skin.
Speaker 3: So capsayasins spicy. That's spicy.
Speaker 1: Yeah, that's the stuff that gives you the spicy feeling
Speaker 1: if you're eating peppers or something.
Speaker 2: So they would like internally pepper spray these mice.
Speaker 1: Yeah, you always find the most horrible way to say
Speaker 1: these things when we talk about animal studies. But I
Speaker 1: am going to just use the phrase the injection for
Speaker 1: the rest of.
Speaker 2: This description, if that makes you feel better.
Speaker 3: Kelly, all right, All right, Well, do you want to
Speaker 3: know the answer to this or not?
Speaker 2: Yes? I do?
Speaker 5: Please?
Speaker 3: Okay? You all right?
Speaker 1: So they inject mice with this capsaiusin analog and the
Speaker 1: mice did get gray, but they got like salt and
Speaker 1: pepper gray like me. So it wasn't they didn't turn
Speaker 1: completely gray. It wasn't patches. It was exactly what you
Speaker 1: would expect if you had hair follicles on random cycles.
Speaker 3: And some some of them started turning gray.
Speaker 2: And did they look at the microbiology of it, like
Speaker 2: can they see the melanocyte dying or doing something or.
Speaker 1: Giving up or yeah, So that's the next thing that
Speaker 1: they did. So next they said, okay, we know that
Speaker 1: the we've got these mice that will turn gray sort
Speaker 1: of like humans do, So what's happening. So then they
Speaker 1: they decided they were gonna for the stress or they
Speaker 1: were going to just.
Speaker 3: Keep using this injection.
Speaker 1: So then they used the injection and they looked at
Speaker 1: what was happening with the melanocyte stem cells and with
Speaker 1: the milano sites, and what they found was that the
Speaker 1: melanocytes stem cells were like disappearing, oh, but the milana
Speaker 1: sites were staying where they were, and so all of
Speaker 1: the melanocytes that had already been made were fine. They
Speaker 1: kept making the black pigment for these black mice, but
Speaker 1: the milanocytes stem cells were gone. So the next time
Speaker 1: a phase started again, no new melanocytes were made, and
Speaker 1: those hair follicles would become gray.
Speaker 2: So gray is the default color. If you don't have
Speaker 2: a melanocyte, then it's just gray.
Speaker 1: Yes, right, And so they're like, Okay, where did these
Speaker 1: in a site stem cells go that are supposed to
Speaker 1: be there to make sure you've got the cells to
Speaker 1: give you color every time the cycle starts again. So
Speaker 1: that was the next question that they wanted to ask.
Speaker 1: And so one idea that's been going around for a
Speaker 1: while is that when you get stressed out, something about
Speaker 1: your immune system attacks your like hair follicles, and something
Speaker 1: about that makes it so that your hair goes gray.
Speaker 1: And so we've done so much work on mice in
Speaker 1: the lab. Now that you can just like pop open
Speaker 1: a mouse catalog and you can order mice that like
Speaker 1: have various parts of their immune systems that don't work anymore.
Speaker 5: Wow.
Speaker 1: And so they like ordered some mice that don't have
Speaker 1: T cells, or don't have B cells, or like they're
Speaker 1: lacking various parts of their immune.
Speaker 2: Cells, meaning that there's like an industry that manufactures mice
Speaker 2: with specific deficits that are useful for scientific experiments.
Speaker 5: Yes, yeah, amazing.
Speaker 1: So they essentially ordered some mice who don't have like
Speaker 1: good immune systems in a variety of different ways, and
Speaker 1: they gave them these injections and they still went gray.
Speaker 1: So that was pretty good evidence that it's not something
Speaker 1: about the immune system that's important for creating this gray.
Speaker 1: So the next question they wanted to know was, Okay, well,
Speaker 1: is it something about stress? And usually when you are
Speaker 1: thinking about stress, you think about cortisol or ner adrenaline.
Speaker 1: So cortisol is a hormone that humans make and we
Speaker 1: release it in times of stress. And what it does
Speaker 1: is it helps us like mobilize energy. So for example,
Speaker 1: if you're being chased by a lion, you want to
Speaker 1: make sure you've got as much energy available as you know,
Speaker 1: as many like calories that you could send to your
Speaker 1: muscles or whatever, so that you can run away from
Speaker 1: that lion. It's not going to make you faster than
Speaker 1: you usually would be, but as fast as you're able
Speaker 1: to be. They want to make sure that you can
Speaker 1: be to try to get away from that lion. And
Speaker 1: then after that stress or it tries to help your
Speaker 1: body like recover from this massively horrible thing that just
Speaker 1: happened to you. And so for us, that hormone is
Speaker 1: called cortisol. Mice have a closely related version called cordiicosterone,
Speaker 1: and so they wondered, Okay, maybe it's something about cordicosterone
Speaker 1: that causes graying. And so it turns out that the
Speaker 1: melanocyte stem cells have receptors for cortocosterone. And so what
Speaker 1: that means is that these stem cells can bind to qrtoicosterone.
Speaker 1: And what usually happens when a receptor binds to a
Speaker 1: hormone is that that hormone is sending some message to
Speaker 1: the inside of the cell that the cell needs to
Speaker 1: do something. And usually what that something is is like
Speaker 1: you need to go into your genetic blueprints and start
Speaker 1: making some new compounding.
Speaker 3: Yeah.
Speaker 1: So what they did amazingly is they said, Okay, we're
Speaker 1: going to essentially take the receptors off of the melanocyte
Speaker 1: stem cells, and now we're going to inject the mice
Speaker 1: with the capsais and analog and see what happens. And
Speaker 1: those mice still got gray hairs. So it wasn't about
Speaker 1: the glucocorticoid stress hormones, because even when that hormone can't
Speaker 1: talk to the melanocyte stem cells, you still get gray hairs.
Speaker 3: Are you with me? Because this is kind of confusing,
Speaker 3: but it's beautiful how they're doing this step by step.
Speaker 2: I didn't follow gluco corticoid, but I think I do understand.
Speaker 2: The argument here is that these melanocyte stem cells, the
Speaker 2: things that you need in order to make new melanocytes,
Speaker 2: are disappearing. And they have a button on their outside
Speaker 2: that responds to this stress hormone. But when they disabled
Speaker 2: that button, it didn't change anything. So they don't think
Speaker 2: that pressing that button to distress is killing these melanocytes.
Speaker 3: Thank you, Yes, that's a great way to say it.
Speaker 1: Okay, okay, perfect, And they have another button for nora
Speaker 1: adrenaline and nor adrenaline is just another chemical your body
Speaker 1: makes when you're stressed out, but it comes from different places.
Speaker 1: It can either come from your sympathetic nervous system, so
Speaker 1: it can come from nerves that talk to your hair follicles,
Speaker 1: or it can come from these glands that sit on
Speaker 1: top of your kidneys. They figured out that if you
Speaker 1: remove this button for nor adrenaline, they don't turn gray. Oh,
Speaker 1: and they figured out that the message is not coming
Speaker 1: from on top of the kidneys. The message is coming
Speaker 1: from the nerves. Oh, I'm simplifying a little bit because
Speaker 1: I realized I was getting a little two in the weeds.
Speaker 3: But anyway, it is coming from the nerves.
Speaker 2: Wow.
Speaker 1: And they were actually able to like use this neurotoxin
Speaker 1: to keep the nerves from sending the message to the
Speaker 1: hair follicles and they didn't turn gray when you like
Speaker 1: messed with the nerves. So it's definitely the nerves that
Speaker 1: are sending the message to the melanocytes that is essentially
Speaker 1: making the melanostes disappear.
Speaker 2: And what's the connection then with stress is something about
Speaker 2: the stress that makes the nerves send this message.
Speaker 1: Yeah, so you stress someone out, their sympathetic nervous system,
Speaker 1: their fight or flight system is like, ah, they've released
Speaker 1: nora adrenaline, and that nora adrenaline binds to the melanocyte
Speaker 1: stem cells, so you're the button on the melanocyte stem
Speaker 1: cells has been pushed. But if they are in the
Speaker 1: phase where they're supposed to be sleeping, you've woken them
Speaker 1: up from their sleep and they kind of freak out,
Speaker 1: and instead of I don't know, going back to sleep,
Speaker 1: they start doing something totally unexpected. They all start turning
Speaker 1: into other kinds of cells. I think they're turning into melanocytes,
Speaker 1: and then they migrate away, and so by the time
Speaker 1: this process is done, you don't have any more stem cells.
Speaker 1: They've all done what's called differentiated, which is a fancy
Speaker 1: way of saying they've turned into a final version of
Speaker 1: a cell, and they can't make new like melanocytes anymore.
Speaker 1: And then they migrate away, and so they're not there anymore.
Speaker 1: The next time your hair cycle starts again, they've wandered
Speaker 1: off for reasons we don't understand. And so something about
Speaker 1: freaking out from some stressful event totally like discombobulates your
Speaker 1: melanocyte stem cells and they wander off.
Speaker 2: So that makes sense as a mechanism to explain why
Speaker 2: this happens. But why would melanocytes stem cells have this button.
Speaker 2: Why are they sensitive to the presence of these stress hormones?
Speaker 5: We don't know.
Speaker 1: Ooh yeah, So there has been a connection between pigment
Speaker 1: producing cells like melanocytes and our nervous system for you know,
Speaker 1: like a really long stretch of evolution. So for example,
Speaker 1: octopuses and other cephalopods, if you stress them out, they
Speaker 1: will talk to their pigment producing cells to like change colors,
Speaker 1: kind of like blend in with the environment. But that
Speaker 1: doesn't explain why we have nervous systems that are like
Speaker 1: talking to our melanocytes and our hair follicles. But there
Speaker 1: is this like long connection. Maybe there's some reason why
Speaker 1: it still benefits us that we don't know. But when
Speaker 1: I read the discussion of this paper from twenty twenty,
Speaker 1: they were pretty much like not really clear why this
Speaker 1: is happening, like what the evolutionary benefit would be. Maybe
Speaker 1: it's something that was beneficial millions of years ago and
Speaker 1: there was just never a reason to decouple these connections.
Speaker 2: Maybe it's not so bad for people who have experienced
Speaker 2: stress to advertise that by showing off their gray flowing locks,
Speaker 2: so people know, Oh, you know, Kelly's been through something.
Speaker 2: Let me ask her opinion.
Speaker 1: That's what she's probably wise because she experienced Yes, right,
Speaker 1: grad school gave her gray hair.
Speaker 3: She can tell us to not go No, I had
Speaker 3: fun in grad school.
Speaker 2: And so is this only something that happens in mice
Speaker 2: or is the same mechanism happen in other animals, like
Speaker 2: in people.
Speaker 1: I think it happens in other animals too, Like, I mean,
Speaker 1: dogs definitely go gray. I don't know if they go
Speaker 1: gray for stress, but like, I think, if it's happening
Speaker 1: in mice, it's probably happening in other animals too. So
Speaker 1: I'm guessing this is a pretty common thing.
Speaker 2: And this suggests it might also be a treatment available there.
Speaker 2: You could somehow protect those myocytes so they don't get
Speaker 2: that button pressed.
Speaker 3: Yeah.
Speaker 1: So one, I want to note that it's really refreshing
Speaker 1: to have you be the one mispronouncing a word for once.
Speaker 1: I'm like feeling great about that. And I guess we
Speaker 1: you know, we both give as good as we get
Speaker 1: in terms of.
Speaker 3: Picking on each other.
Speaker 1: But yes, it does suggest that if somebody has had
Speaker 1: like a super stressful experience. Maybe you could try to
Speaker 1: calm them down in some way quickly, in a way
Speaker 1: that might rescue their melanocyte stem cells. You'd have to
Speaker 1: do that pretty fast, because once those stem cells have
Speaker 1: migrated away, they don't come back.
Speaker 3: Yeah, then you've lost them forever.
Speaker 2: Wow, fascinating.
Speaker 1: I really appreciate this question, Joe, because this was, like,
Speaker 1: this was so much fun to read about. Like there
Speaker 1: were lots of things in this paper where I was like,
Speaker 1: I have no idea what you're saying. This is like
Speaker 1: crazy molecular biology stuff, but like, wow, this was a
Speaker 1: cool set of experiments that anyway, I am going to
Speaker 1: try to make sure nothing super stressful happens to hasten
Speaker 1: my decline into silver foxhood, but I'm sure I'll rocket
Speaker 1: either way.
Speaker 2: Well, fortunately it doesn't sound like answering this question was
Speaker 2: that stressful for you, which is a relief. So let's
Speaker 2: send it over to Joe and hear about whether it
Speaker 2: gives him any more gray hairs.
Speaker 7: What a colorful journey to finding that association. I'd like
Speaker 7: to mention that this kind of science, whether search for
Speaker 7: an answer becomes a series of experimental steps, is research
Speaker 7: of the best kind. It's also one everyone can do
Speaker 7: in their own way. Thank you for getting to the
Speaker 7: root of this question without stressing anyone out in the
Speaker 7: same vein as Kelly, I too have a few hairs
Speaker 7: of wisdom. That said, I'm definitely still going for the
Speaker 7: spicy foods. Whether your head is black, blonde, bear, or
Speaker 7: glistening gray, stay show everyone.
Speaker 2: All right. Thank you very much everybody who sent us questions.
Speaker 2: We really do love hearing from you, and one reason
Speaker 2: is that it gives us an excuse to dig into
Speaker 2: some corner of physics or biology that we always wanted
Speaker 2: to understand and never had a reason to spend an
Speaker 2: afternoon on. So thank you very much everybody for being
Speaker 2: curious and for sharing that curiosity with us.
Speaker 5: Thank you.
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