Hey, everyone, I've got a new fun physics book out now.

It's called Do Aliens Speak Physics?

And I think it's a lot of fun.

But don't take my word for it.

Here's what Lake Crouch, famous author and smart guy, said.

Do Aliens Speak Physics is a charming, thoughtful meditation on the common language of the universe, a book which asks important questions about the fundamental nature not just of our existence, but of reality itself.

So go out and pick up a copy of Do Aliens Speak Physics?

I think you'll enjoy it.

This pregnancy thing is just the pits?

Is there anything we can do to speed it up a bit?

When we're undergrade stress?

Can we really lift a car?

Or is that an urban legend that's gone a bit too far.

Bacteria can be beneficial, as I've come to understand, But what about viruses?

Do they ever lend a helping hands?

Whatever questions keep you up at night are.

Sometimes beyond the intellectual grasp of Daniel and Kelly.

So on today's show, Doctor Capo Hannon joins us to answer questions that stumped well Kelly in particular.

Welcome to Daniel and Kelly's Extraordinary Universe plus friends.

Plus friends, and note this friend studies reproduction and sex, and so you should decide ahead of time if that's appropriate for young children.

Bigs.

Hi, I'm Daniel.

I'm a particle physicist, and I don't know the answer to every single physics question you might imagine.

Hello.

I'm Kelly Windersmith.

I study parasites and space, and wow, y'all ask me a lot of biology questions that I do not know the answer to.

And I was on a road trip with my friend cap Ohannon.

We were driving through Wales.

We did the show together called Moms on Mars, where we talk about how difficult reproduction on Earth is and how it would be even more complicated on Mars.

And it's not a great idea to rush into that.

And I mentioned that I have this new podcast and I have these amazing listeners who send me a bunch of questions that I don't know the answer to, even though they're about biology.

And Kat was like, dude, I'll come on an answer.

I was like, sweet, So we decided to do that.

Well, it's incredible to me how broad biology is as a field.

I mean even physics.

Like in my department, we have people who do particle physics and condensed matter physics and plasma physics, and the fields feel totally different.

But like we have sixteen different biology departments here on campus.

You know, like the breadth of stuff from like ecology to microbiology to medical stuff is just really astounding.

I don't know why y'all even call each other biologists.

No, it's super different.

Yeah, I was at a university that had, you know, immunology, ecollege, nematology, botany, and it's they are all very different.

And I'm very flattered that the listeners think that I can handle any biology question.

But I do every once in a while, and buy every once in a while, I mean quite often need to lean on a friend who's an expert mm hmm.

And I've thoroughly enjoyed hearing about all these biology questions.

I'm so glad folks out there are curious not just about the physical universe and cosmology and particles, but how all this gunky stuff inside of us works.

We can go on doing its meat machine for so many years.

It's amazing to me as well.

And of course I'm interested in biology.

I hear about it at home, but it's wonderful to also get to dig into it on the podcast.

So send us your questions about physics, about biology, about all the gunky stuff inside of you.

Write to us too, questions at Danielankelly dot org.

We will answer your questions or do a little bit of research or put it here on the podcast to.

Joke about, to joke about, and try to answer.

Oh yes, and also answer yes.

We try to get answers one way or another to nearly every question, although there are a couple that are just way too far out of our wheelhouses and we have to throw up our hands and say I'm so sorry.

But I think that gives us credibility because you know, sometimes you don't know the answer, and you should say you don't know when you don't know.

That's one of the joys of working at the forefront of knowledge is you just get to throw up your hands sometimes and say nobody knows, we don't know.

It's one of the mysteries.

That's right, or it depends is my favorite, or we have no idea, that's right.

There you go.

But Kat has an idea, and so Kat will be answering the questions today.

So let's go ahead and bring Kat on the show.

On today's show, we have my good friend Kat Bohannon, who completed her PhD in twenty twenty two at Columbia University, where she studied the evolution of Narrative and Cognition.

Eve How the Female Body Drove two hundred million years of Human Evolution is her first book.

It's a New York Times bestseller and was listed for the Royal Society Prize, the Orwell Prize, and the Women's Prize in twenty twenty three.

She lives in the US with her partner and her two semi fairwah children.

And those are her words, not mine.

I'm sure they're lovely.

Welcome to the show, Kat, Hey.

Folks, thanks for being here for helping us answer these amazing questions.

I'll do it, I can.

Questions are great.

Yes, yeah, So we've been getting a lot of questions about the human body, and the first person I think of when I think how does some part of my body work?

Is I should ask Kat?

And so we're passing these questions to you.

Okay, So let's go ahead and listen to our first question.

Hello, Extraordinaries.

I'm Andrea from Italy, a big fan of the podcast.

In your Books, youre with me?

Is my wife with some questions for you?

Probably Maureen Kelly's ballpark.

Hello there, Alessandra here.

My question for you is what determines the length of pregnancies in humans and other species?

Is it correct to assume it's a function of the needed number of cells?

That said, have there been studies on how to shorten gestation?

If so, how would that be technologically achieved?

And lastly, what's social implications with a rise as a consequence of shortened gestation in humans?

Do you think you can affect the current birth rate or other aspects of our social structure?

Ooh, so that is a meaty question, full of many questions inside that little package of question.

But do you think this is somebody who just went through pregnancy and wished it was shorter?

She was like, oh my gosh, how can I end this sooner?

I mean, that's one of those things anyob I will tell you that by the time you get to your third trimester stating people are ready, They're like, you know what, I'm freaking good, Yeah, let's let's do this thing.

In fact, the only thing that could probably push any reasonable person over that totally reasonable fear of the process of giving birth is the idea of continuing to be pregnant as an alter you know what I mean.

Oh yeah, So you don't think anybody was like, hmm, this has been cozy.

I could use another forty weeks of this.

Oh well, beings are a little kray.

So I'm never gonna say no one, you know what I mean.

There are some people, some unicorns who like the knocked up state and are like, I want more of this, I want more of this.

I think most of us it's a mixed bag.

There are bits we like, bits we don't like.

It's very complicated, but most of us, by that third trimester, if we make it there are like, yeah, get this thing out of me.

Now, this is a Ridley Scott scenario.

Get this thing.

Out yeah yeah, yeah, yeah, yeah.

Absolutely.

So the short answer to have there been studies to shortened gestation is yeah, and we're already doing it, but not on the development side.

On the like, can we do it outside the body side?

Right?

And that's a slightly easier thing to rig right.

So for example, literally all IVF as we currently do, it shortens the process by which you know, a thing that becomes a human later is in the body at the front end, because we are fertilizing that egg outside of that pelvis.

We are doing it in a different way.

We are doing it.

Sometimes it's a tube I think nowadays it's a pea tradition.

Then too, it's complicated, depends on the lab there's a history of it.

There's a lot I don't know, but yeah, basically, so like a blasticist of five or six stay blasticist, which is kind of a basketball of cells.

So at that stage of development, which isn't yet gestation.

Gestation technically is when it starts burrowing into your body, into your uterus, right, that's your start of pregnancy.

So this is just cells doing crazy stuff, making a hollow basketball.

That thing is not in your pelvis until it gets transferred in, right, So that's already shortening what's going on your body, and the other end gets more complicated.

Very late stage pre meis basically now there's a lot of development around improving a nickqu by creating a more womblike environment.

Right, So you can think of the whole NIKEU as shortening just station even though the gest state in person probably didn't want to thank you.

Those are premies right, But now we're trying to improve it because like the way we do it now is damaging to the lungs.

Those lungs are you know, often not quite ready to breathe air, they're still developing.

So we're working on having that be a more fluid environment.

There's a thing called a bio bag that can mimic more of that liquid environment.

It's not out there, you're not going to find it in the hospital, but those are labs developing that stuff.

But that whole middle bit, which is basically when that placenta attaches on up until very late stage pregnancy, we don't have that yet.

We don't have a way to have a mammalian pregnancy like happen without a uterus and without a body that's hosting that uterus.

Right, So that's like the counterintuitive way of thinking, how can we shorten gestation The way they're really hoping, which is speed up, is a lot crazier and actually unpacks whole bag of worms that we don't know in biology, which is really interesting, like why the hell do fetal cells multiply so rapidly?

And then for some reason, once you achieve a certain kind of body organization, certain body plan, some of those tissues start slowing down their replication cycle, and some of them stay fast, you know, like when you're building a body, which again is actually not just making cells but also having them migrate right to different areas in that developing embryonic body.

You know, there's just a whole city infrastructure going on in there, right, and it's going really fast.

It's going really really fast, and then some parts of it slow down.

Like I couldn't build a baby faster than that, for sure, it would take me a lot longer.

So this is pretty impressively quick, right.

I mean, technically we could attach a placenta to like your abdominal wall, but you probably don't.

Want to do that.

You probably that's not like on your Bingo card for twenty twenty.

I mean, I know there's been a lot that's been surprising this year, you know, like the but not not like knocking you are now no no, no, no no.

Well put this in context for us, like our humans do, they have a longer gestation period than other great apes.

For example, they are human babies more developed or less developed than like chimpanzee babies when they're born.

See.

I think that's also a really good way of framing it, because like when you get born as a mammal is not like this set thing, like you are so ready for the world or so unready for the world.

Like when mice are born, they're pretty fetal.

You know, we call them pinkies.

You know, they have no hair yet, their eyes aren't open, their ears aren't unruled.

Like even to poop, the mother mouse needs to lick along the abdomen to like stimulate you know, them to pee, and they will actually die of not defecating and peeing if they don't get that stimulation in those early wow phases of being So is that really developed?

Is that really being born?

Right?

And that's that interesting thing, Like all mammalian species have a different level of development or readiness, you know, for existence outside that body, which is really interesting.

And so human bodies when we're born, a lot of people make a lot of hay out of the fact that we're pretty freaking useless.

We can't hold up our heads, like we are just barely able to exist compared to say a chimpanzee or a gorilla or many other primates.

Right, But I didn't have to lick Ada's belly so she could poop.

So that's pretty that's pretty great.

I'm calling that a win.

Sorry, go ahead, No, no, that is really great.

But you trying to make sure she didn't snap her stupid neck was definitely like a thing that other monkey moms don't have to do.

Right, So we are a needy baby species.

We are like, gotta do more to keep this thing alive species for sure.

And Holly Dunsworth did the most famous research on this.

So for a long time we thought human babies were born because our heads are stupidly large, and our vadge is really not that large.

It's actually not the vadge that can stretch or tear.

Don't think about that too hard.

But like the actual pelvic inlet, the bone opening, you know where the babies come out at the bottom, is small compared to how big a thing we got to push out.

So we thought that was the obstetric dilemma.

We thought that was why we were born when we were born.

But Holly Dunsworth did some really great research saying, actually, this is a metabolic threshold.

Actually it's more like how much longer can you gestate this super greedy, metabolically costly fetus before your local resources are not sufficient.

In other words, it's actually an ecological concept.

Right when are mammals born, It's like, how much longer in our case can this body continue to literally bear the load of this resource hall right before it's like, oh no, we got to switch to lactation.

You need to get the hell out of here.

This is not this is not cool.

Is it calories or is it space?

Like are they pressing on your lungs in your heart or is it both?

I did not enjoy how difficult it was to breathe in late term pregnant.

Same you know, I wasn't cool with like how literally my diaphragm was compressed out for by this new mask growing not nah nah no, no, no, no, not fun.

But so yeah, that's not great.

But no, it's actually it's calories and general just load.

Now, metabolic load is going to be a cost that isn't simply how many calories transferred, but also what are the resources you need to continue to exist jes dating while bearing this thing that also requires resources, So that's not simply you transferring resources.

It's also how much does it cost for you to carry this thing around?

How much does it cost for you to care to have a heart that's still working pumping this much blood.

So that's like a whole it's a complicated, sweet oft stuff, but that's the general idea.

We give birth when basically it's too costly to continue doing this thing, you know, and that was done so great insight that it's not about the head size, although head size also sucks.

Well.

I remember when my kids were born, feeling like, Wow, this baby was better suited inside the womb because you know, you didn't have to worry about it crying.

It was fed automatically, you know, the whole diaper thing, Like, it just felt like it was so much easier.

Also, of course it wasn't inside me.

There's that.

It's an important insight.

Yeah, really significant.

Bell just went off there.

Yeah, thank you for acknowledging that.

Uh huh, hello, I heard that.

No, for sure, I mean technically that mother was having to like eat and drink and go to the bathroom a lot, so I wouldn't say it was automatic.

It's just that you didn't have to think about feeding it, and you didn't have to think about dealing with its cell waste, like how often and where is it peeing?

You?

Know, my first child had a penis.

My son definitely peed not just on me, but greatly upward.

I definitely.

My face was peed on taking care of that thing.

Oh yeah, my daughter did not have that.

It was fascinating.

I was like, oh, it could be like this.

This is better.

So the listener wanted to know if the length of pregnancy is a function of the number of cells.

But it feels like what we've said is maybe number of cells matters, but it's also how developed the baby needs to be before it's ready to enter the world, which depends on like the evolutionary history of the animal.

Does that sound fair?

I think that sounds fair.

I mean elephant chestation takes a long time to build a big freaking body like that.

That is true, and it's.

Very rare for elephant twins almost never.

Oh interesting, both the metabolic load of that thing and also it's an elephant.

Yeah, and it's in you.

So even if you're an elephant, you're growing an elephant.

Oh god, you know, so that's that's the thing.

So yeah, so that newborn size, just sheer size is definitely definitely a factor.

But you know, even as adults, our cells are replicating at very different rates what their cell cycle, like, how long do you go through that early cell phase into when does it finish out?

The lining of your intestines can finish a cycle in like I think ten hours or something like that, you know, whereas your liver can take like a year.

I'm pretty sure it's the hpatasite.

It can take like a long time.

And then of course the most famous case of the longest cells to complete their cycle is our freaking eggs.

Right, So, like Kelly, when you were inside your mom, well the tissue and the feetus, then that became you and you were developing those nascent follicles in your little bit ovaries, right, those things reach a certain stage and then just stop, just hang out, just pause, some of them for as many as forty years or more, right, whereas the rest of your cells are definitely not doing that.

So actually, one of the big mysteries in biology is what is regulating all of that?

How does that work, What are the switches, what are the inhibitions genetically and otherwise that and what changes that later on?

Because actually that's one of those things in cancer, you get a lot of cells that then, say a liver tumor that originates in the liver.

Right, how do you take a cell that has a really long turn over time and have it start multiplying rapidly?

Right?

What's controlling that?

If we can actually figure that out, oh we can keep a lot more people healthy.

Well, say more about that, because say we understood what is regulating this isn't that downstream of something else which is regulating it.

It's in the whole thing, some complex Rube Goldberg machine.

It's not like if we understood, oh it's this level of hormone, you could just like give somebody more and it would happen faster, or take it away to make things slower.

Isn't it an enormously complex device that we have almost no hope of being able to like manipulate to our ends.

Daniel finds biology frustrating.

Yes, it's not just a particle.

I was just about to say, you seem to just be describing biologies.

These are complex systems interacting complexly.

That's what what where is?

Okay?

Yeah, it's nice.

It's nice in physics that you can just like get your foil from Costco and build your experiment.

But we have to have things make babies.

Okay, you just described all the physics.

That's amazing.

Wowols from costco that's my entire budget.

Yes, that sounds nice.

Well, unless you're actually trying to build certain you know there are there are there are different levels of cost and experiments.

Yeah, yeah, yeah, yeah.

Man, So I think I I completely agree with you that there isn't going to be one smoking gun for what regulates all this stuff.

And like in oncology, there's definitely a case that some cancers are what you're describing with the hormones is environmentally triggered cellular pattern changes, right, where like if you get your more estrogen and you have a kind of breast cancer that is especially responsive to estrogen, then you want to downregulate that to keep the cancer at bay if you're a survivor.

Right.

There are many kinds like that.

That's also true of you know, prostate and testicular cancer that you want to downregulate certain androgens so that you don't end up with more of that cancer profile.

Right.

So that's manipulating the environment of those cells.

And there's a lot of stuff that changes your replication rate that doesn't have to do with that.

But you know, like One of the things that we're starting to think about in aging science is, Okay, what does resource availability do to sell replication?

We know, for example, in diabetic patients that they have a higher risk profile for a number of different kinds of cancers, and the thought is that many cell types are responding to that higher level of local sugar.

Basically, you know that that is changing what the cells are doing, almost as if, like in an ecological problem, there's more resources, so we can make more babies, you know, we can replicate those cells faster.

Right, So, really thinking about the body as a bunch of different local environments is surprisingly useful.

But again, is that thing where like, can we speed up gestation?

Well, the first thing you think of is like, so are we just going to turn all fetuses into cancer?

Just a whole lot of cancer, because that's probably what you're proposing to try to speed up a basic body plan without knowing what.

All you're doing.

I'm guessing that's not what she had in mind.

But it's a good way of highlighting.

No, she wasn't thinking a lot of cancer.

She was just like making me less pregnant for less time.

That's right.

It's a good way of highlighting the complexity I think.

But let's say that somehow you could, right, somehow you figured this out, and you could have a baby in six weeks instead of you know, forty weeks.

Okay, what do you think that would do to the social structure and you know, the decisions people are making about having babies.

We've heard on the podcast recently about how, you know, birth rates are dropping worldwide.

Yeah, birth rates are dropping around mostly wealthier, mostly white women.

But we could get into that debate another time.

Actually, our global population continues to grow, and it's fine, Okay, So now that I've done that PSA, I'll just quickly say that, like, we're definitely thinking about a matrix scenario.

Now we're talking about external wombs.

A human body would not be able to supply, you know, the resources necessary without dying to create a whole human body in six weeks in a uterus.

Besides just having that uterus grow to sufficient size, remember that normally it's the size of a freaking adult fist, and we're now making it a basketball.

So that's a thing that takes time, right, It's also simply again that metabolic load.

How do you transfer sufficient resources and stay alive.

That's the mammalian conundrump.

Right.

Yeah, So so okay, so external wound would be a major thing.

And as soon as you have that, then the social implications are absolutely massive.

Right that, now there is no individual body that needs to bear you know, the burdens and the blessings, but mostly burdens of making bodies inside of it.

Right, That actually changes a lot about what it is to be a person with the uters.

That changes a lot about things that we assume are simply part and parcel of being female, which could be both really cool and really weird.

All right, so let's go ahead and we're going to share this answer with the listener and see what she had to say.

Thank you so much for your answers.

Kat.

Let me clarify that I'm not currently pregnant or have been pregnant.

The reason for my question was rather my interest for social policies and how science can shape them.

As a matter of fact, I found especially interesting your insight on how an external leaders would disrupt our traditional understanding of gender roles.

That is definitely something to think about.

I.

On the other hand, found very interesting the idea of birth as a metabolic necessity that explains how some newborn animals can instantly run while others can't even stand.

Thank you all and keep up the good work.

Bye bye.

All right, and we're back and we are on to our second question with Campo Hannon, and so let's go ahead and hear the listener question.

Hi, Daniel and Kelly.

I was recently with a group of friends playing a superhero RPG and a question was posed that I'm hoping you can help us out with.

Can humans really lift a great deal of weight in times of great stress?

I've heard that humans have restrictors on their muscles, otherwise they'd hurt themselves with how much they can really do.

I've also heard the story of a mother lifting a car off of her trapped children.

Are either of these things really true?

Would an ordinary non body built human be able to lift a car a foot or so off the ground if they really needed to?

If so, what happens in our bodies to make such a thing possible?

If not, where do you think stories like restrictors and super strength moms come from?

Thanks in Evans.

Can we start with just what happens when you have an acute stress experience?

So, like something stresses you out.

Let's say, not stresses you out enough that you need to try and lift up a car?

What does our body do there?

And then maybe we can move to can you lift up a car if you're stressed enough?

Well, first, I think one of the things that's really great about these accounts, which have to do with like removing normal limitations on muscular use and things like that, you know, during periods of intense adrenaline, intense stress, what it's often called in the literature.

I looked this up is hysterical strength, which is.

Which is amazing.

That's amazing to me, knowing anything about the history of feminism and the term historic, that's amazing to me.

Just picturing these people just losing their minds.

I love all of that, you know.

And there are these accounts of people like lifting cars off of trapped you know, teenagers and toddlers and things like that.

And again the listener was right to say, we're talking like one wheel.

You know, if you think in basic physics, those other wheels are still on the ground.

You are a temporary jack on one corner there, So you're not lifting the whole car, you're lifting a certain amount.

What you're really doing is a dead lift, and so you, as an untrained person, are not doing a dead lift that somehow is better than like the world record keeper of deadlifters.

Right, that's not doesn't matter how much adrenaline you got, babe, that's not a thing.

What's interesting about it to me is like, Okay, yeah, like Kelly says, something happens in your body.

You get that adrenaline going, and two things are happening.

One, a lot more blood is rushing to your muscles, all of your muscles really, but especially the ones you're trying to activate.

Your heart rates accelerating and what have you.

That's a thing that's happening.

And a lot of you know, in that blood, you're getting a lot of sugar transfer, a lot of energy transfer, not so not just local but also body wide.

Energy is going to the thing you're trying to do.

But what's really interesting about this moment is that you're actually affecting your brain that much more than the local muscles.

We used to think that the brain was kind of not really involved in these caps on your strength because remember when you're when you're using a muscle, you don't want to use all your strength to lift your coffee cup.

It may feel like that at six am, but it's not that at all.

Right, you don't want to blow out your back for reasons by ridiculously lifting your coffee cup.

You're you're just going to use what you need, right.

But if you're trying to lift a car to save a life or save your own life.

This thing that happens with people who are trying to escape war areas, and you hear stories of soldiers or even mothers with children walking for days with no food or water, going up into the hills, surviving extreme temperatures.

You know that normally we wouldn't really be able to do.

And what's happening there is that your body is willing to damage itself to save its life, or willing to damage itself to save another's life.

That's what's really up.

And that's actually a brain thing.

That's a brain thing more than your heart rate thing.

And so what your brain is doing it is it is ignoring more of those pain signals.

And that's the thing.

So you literally experience less pain during this period of crisis, right, because if you're not noticing the pain, that literally means you're experiencing less pain.

What is pain, it's a thing happening in your brain.

Right.

So, actually a lot of studies have been done that really, during these moments of intense fight or flight, tense stress, your brain is down regulating its response to normal pain response.

And there is an account of a dude who lifted a corner of a car off an adolescent who later found out that his teeth really hurt because while gripping his you know, clenching his jaw, he managed to crack eight of his teeth.

Wow, while he was lifting.

Right, So that talk about a no pain response, talk about like I am using the limits of my body to save this person's life.

But what I think is really smart about what you said there, Dan is is it's not just you know, this account of what's the heart doing.

It's not just what the brain is doing.

It's also how we understand these experiences after the fact, whether we go through them or someone else does, because these are the stories we tell.

These are the incredible, weird stories that don't line up with our normal experiences of our bodies or other people's bodies, or human capability, you know what I mean, which is situated in our lives, which is culturally situated, you know what I mean.

Like, for example, Dan and Kelly's Incredible Universe exists in a culture of doubt where a lot of times, you know, it isn't that the spirit world is literally imbuing you with extra strength, and that's why, right, you know.

And there are cultures now and cultures in the past that do have that model, that don't find these moments so as extraordinary maybe as we do, because we don't have as much of an explanatory frame for something that feels hard to understand, understandably hard because it's rare, right, And some cultures do have that explanatory frame and then don't find such moments as novel.

Yeah, I never thought of it that way.

Well, yeah, So there's one culture for example, I'm not remembering the name because I am not an anthropologist, but there is one culture that tends to give birth alone.

This is hunter gatherer community, very rare in the human species.

We do not normally birth alone.

But this they like go out in the grass, they go out in the fields, and they do that.

Now, it's not that they're not prepared.

Let's make it clear.

Their whole childhood has stories of how to do it, and so they have their own knowledge and there are people who help in certain cases, you know what I mean anyway, but they have a frame where to get through the pain of it.

They are calling down strength from the universe effectively, So their experience of contractions is this deeply different thing where they are experiencing the pain as a calling down of strength, which is good for them.

No, I did not have that.

I just had your basic fear of death.

I'd rather have the epidural really, but I had that too.

I had that too, but it actually didn't work as well.

But I still am grateful for the portion they did work.

So the way to think about this is that your body has certain capabilities and certain limits which are just physical like there's no way I'm lifting a boulder, yep.

But there's also warning signs your body say to you when you're starting to damage yourself, and those typically limit what you're actually going to do.

But in moments of great stress, essentially it ignores those and you're willing to do stuff that damages yourself or cracks your teeth, depletes crucial resources to survive the moment.

But that's a subconscious thing, right, It's not like that's right I'm saying, Daniel, I'm going to turn off these pain regulators because I think it's a good idea.

It makes it sound like there's some sort of strategizing or some thought process there, But if it's subconscious, there must be some mechanism there.

Do we understand how that works at all?

Do we understand how pain works in the brain?

Oh?

Kind of.

Kind?

We've made great strides.

I will say that it's you know, it's been studied that there are a number of pro athletes of various types who are known to have effectively higher pain tolerances than the average population.

So the most famous pain tolerance thing is shoving your hand and a thing of ice water, because we all, you can't think you're way out of it.

It's your hand lowering temperature, and it's one of the best ways to gauge what is your basic pain tolerance?

Here?

What's your nose sceptor?

They like, what do you do?

And many of these athletes do, indeed, have start to feel a lot of pain later and respond to it and feel that urge to take it out later.

So part of what may enable some of those extreme athletic things isn't simply training, but also kind of being wired differently.

So how do you differentiate between I put my hand in and for some person it starts to hurt immediately, and for some people it takes five minutes to hurt, and it hurts both of us at the same time.

But I am just better at handling pain for longer.

Like, are those two different things?

I think that that's a thing that we all want to do with the idea of pain.

We want it to be about the virtue of endurance, you know.

We want it to be about like, you're more bad ass because you just deal with it, right, But that actually doesn't allow for bodily difference.

Actually, there are a lot of bodies that are just sending a more muted or blunted or delayed pain signal, and that's not because they're badass.

It's just that it's a different body.

But then there is a kind of mindfulness training.

There is a thing that a lot of people with chronic pain have to do, which is training your brain to ignore certain pain signals more so that your life becomes more tolerable, which can in fact make things slightly less painful.

It doesn't truly remove certain kinds of pain, but it can make it more bearable.

Right, So there are different tiers of awareness of pain.

As far as the ice water though, I mean, there is a moment that everyone, except for those rare people who have that genetic condition where they don't feel pain, need to take their damn hand out.

They just can't.

They can't bear it anymore.

It's very very rare to be able to bear it through.

This is not a like badassery thing.

It's one of those basic tests of pain.

Well, my son is an athlete, and I've learned just watching him train and push how much of racing he's a runner, is mental?

Yeah, do I think I can go faster?

And also how long am I willing to sustain this feeling of pain?

And one of the best examples is he was telling me that after the first person ran a four minute mile, then like a bunch of other people did it, and it was just sort of this mental barrier.

People thought, well, that's just impossible, there's no way I could accomplish it.

But then after somebody do, they're like, oh, it turns out he can do it.

I can probably do it too.

I'm just going to go do it.

Sure, It's incredible.

How much of athletic performance is just believing you can do it.

Did any of them get hurt after that?

I'm sure they were all in pain, but there's no amount of believing I can do it that's going to make me run a four minute mile.

Same.

No, that's right, and that's because while we're all sliding towards death, we're not young anymore.

There's just that true thing about aging.

But also maybe you're slightly less susceptible to peer pressure, which hopefully is also an ad Yeah.

Yeah, all right, Well, let's go ahead and see if our listener has any follow up questions.

Hi, Daniel and Kelly and Kat, thank you all for answering my question about humans gaining momentary superpowers or not.

It makes way more sense that our brains just tune out the pain, rather than us turning into a one percent version of a very angry green Marvel Comics man.

I did sort of have a tangential question sparked by what was said.

I've heard that people that can give birth have something that allows them or enables them, to forget the pain of childbirth.

I know conceptually that there is a lot of pain involved, because I will never give birth.

Is it kind of similar to the man that cracked out of his teeth.

Are both brains tuning out the pain or is there a different mechanism at play for people that can give birth versus people that can't.

Ps.

I've listened to the audiobook for Eve and absolutely loved it, So thank you Kat for writing that.

Cheers.

Hey, thanks for the follow up question, and so glad you like to Eve.

Okay, so your question has two parts.

First, do people who give birth really forget the pain of childbirth and not just like on Instagram or completely lying about it?

And two, if they do, is the mechanism similar to that guy who didn't notice he was cracking his teeth when he was lifting the corner of a car or something because of adrenaline.

Okay, so first, it's totally not true that we all forget the pain of giving birth, though thankfully we do forget the pain of being born, which doesn't actually sound very fun at all, So I'm down with that.

In fact, we forget much of the first five years of our lives.

It's called childhood amnesia.

We basically all get it.

It seems to have to do a childhood brain development, and that's totally why you should stop feeling guilty about that time you yelled at your toddlers in public, because they're not going to remember any of this.

Most studies show that as long as you're not actually abusing them, a lot of that parenting crap comes out in the wash.

Okay, so forgetting pain.

Pain is actually one of those things that doesn't get perfectly encoded in memory.

We remember the men side effects of pain, like starting to sweat, like having a hard time moving or breathing fast or whatever, and we can kind of describe pain, like when your doctor says was it a stabby pain or a grinding, dull pain?

But your brain doesn't seem to usually encode totally specific impressions of the pain itself in long term memory.

It's like we save the gist of pain.

It's not like remembering the face of a loved one.

That's a long way of saying we forget a lot of pain all the time.

Do mothers forget the pain of trying to squeeze a bony watermelon out of her vatch?

She might say she does.

She might have been experiencing such total pain delirium, which is a thing kind of like the guy who cracked his teeth.

She's trying to achieve a goal, and her focus on that goal overrides her focus on the pain her body is experiencing to achieve that goal.

And attention is a big memory driver, right, So if you're literally not paying attention to the pain in the moment, you're less likely to remember it happening later.

But women who experience birth trauma, which is a shocking number of people, are more likely to go on and develop secondary tokophobia, that's fear of giving birth for I don't know the obvious reasons.

You tear yourself open to get another body out of your body, and it's a little traumatic, more so for some people than others.

So like they're remembering those painful, terrifying features of that experience really really well too, well well enough that therapy becomes useful or even necessary to go on having a fulfilling life, much less try to do such a thing again.

Right.

So I suspect it's a mixed bag of Some people who usefully glide over the pain of that moment, usually impart because they value the outcome.

Hey look I made a baby, and luckily they have brains that are able to basically downplay the sense memory of what it took to make said baby, which not all people have, and the ability to do that is by no means a measure of how much they value the resulting baby.

It's just that brains are organs, and just like everybody's heart is a bit different, ask any cardiologist, everybody's brain is also a little bit different.

All right, we are back with our third question.

Let's go ahead and listen.

If I understand it correctly, there is a hypothesis that the mitochondria in our cells came from one cell enveloping another, which formed a symbiosis that was mutually beneficial to both.

This is mind blowing in and of itself.

Or I believe that I have heard something similar about viruses.

So my question is this, have there been any positive or symbiotic benefits resulting from viral infections?

Uh?

Depends how you feel about mammalian pregnancy.

Actually on a thing for this show, that's.

Right, because it does seem that so it's a really weird thing that you can have an embryo implant in your uterine wall.

Actually we take that for granted, but actually that's very similar to how cancer metastasies attaches to different tissue.

Normally, local tissue strongly rejects and calls in the immune system when a cell that shouldn't be there is there a cell that it shouldn't be there might be doesn't contain all your genetic material, like an embryo, or it might be like what is this liver cell doing in this intestine or vice versa.

Right, you know, there's a local community kind of thing that says you belong here you don't.

So actually, really weird that we're even capable of it, And it does seem that it may be because we got a cold, like ancient little rat like things got a cold and started attaching interiorly, And that's part of how that seems to work, where some genes are effectively switched off that permit implantation that seems to be strongly tied to what we think was a viral infection.

So cool cheers that we did that.

I'd still prefer to lay eggs, but there you.

Go, there you go.

So I think you're suggesting that viruses can infect you and transfer their DNA yes into ourselves, and we essentially adopt that, and that's part of being human.

That a significant fraction of our DNA actually is viral.

I don't know what would count as a significant fraction, And I don't know that we really know how much of our DNA was or wasn't sourced from a virus, because we're talking really ancient time, which we're looking at basic cell mechanics, like be kind of hard to say what was or wasn't originally, you know what I mean, especially since the listener was thinking about that really ancient case of mitochondria getting in there.

So I don't know that we know.

I will say though, that certainly our cells are being infected by viruses all the time.

Whether or not they make it into that germline, whether they become a basic part of our body plan, you know, in our eggs or in our sperm, is a bigger threshold.

Usually, like a huge number of your cells, dear listener, are presently infected with viruses, some of which may well be passed on in that local tissue, some of which will be totally annihilated by the immune system, right, Like, that's just a constant state of being.

You're so infected all the time with bacteria and viruses and many other things, depending where you live in the world, right, But whether or not your kids then are going to change some feature of their body plan because of that, legacy is a higher bar.

Now there is interesting stuff because there's another thing, so that's like an inherited thing.

So that pregnancy thing is an inherited maybe we'll call it ben official legacy in mammals.

Right, But there is an across the lifetime thing that happens when you're infected with viruses that sometimes is beneficial.

So this is a really interesting case.

So first of all, you are definitely infected with a number of different herpes viruses, that's just for sure, for sure.

True, there are so many of them, and you are definitely carrying So we all got the herp enjoy that, that's right, Yeah, we do.

It makes us feel closer to you.

You know, we're so bonded.

It depends where you got it.

Certainly the one that causes cold soares like over ninety percent of the human population has it at this point, so cheers.

Yeah, And herpes viruses are tricky because a lot of I think all of them, but at least a lot of them if I'm remembering it right.

Again, not virologists, but what I know.

They infect your your nerve tissue, and your immune system tries not to attack your nerve tissue for all the reasons.

Your nerve cells are a thing that your immune system is like, should I attack this like your brain and or your spine and or you know, probably not unless you have a big auto imune thing.

So it's a good place for a virus to hang out and go dormant, which is what herpes viruses generally do.

So there's this one CMV cytomegalovirus.

A lot of people, majority of the population have it, okay, and when you're old it seems to be associated with a number of not great things, like people who are you know, serah positive, Like you can test for it in the blood, you have antibodies to it, you know you're gonna have you're more likely to have certain kind of heart problems and other things.

But interestingly, when you are young and healthy, like in your late teens and in your twenties, it improves your response to influenza.

Huh.

So, if you're infected with CMV, this is a really amazing paper, you are gonna have a better response to your flu vaccine.

You're gonna have a better response to getting infected with the flu.

More broadly, weirdly, CMV seems to do it, and it's not like all herpes viruses do it, like the stein Bar virus.

That's another virus and it doesn't have that effect.

So it really seems to be and we have no idea why, specifically immunomodulating that body while you're young and healthy and interestingly, to a lot of biologists, when you're probably making babies, because when you're old, you're kind of probably done with the baby making thing.

And so if it sucks for you in old age, well, oh well, you know, like evolutionarily speaking, right, but it's boosting you.

It's boosting you.

It's making you survive things like flu better when you're young and healthy.

Cidomegalovirus also sucks when you're a baby, Like it can make you really sick if you're a very young infant.

So new infections at that age actually do very bad things.

It can cause meningitis and blah blah blah.

Basically, it's just the sweet spot, Like specifically, it's it's okay to have it when you're already mostly adult and or young adult, Like right right there, sweet spot, but not so much before, not so much later.

Too bad, you can't just get rid of it.

Yeah.

Yeah, So we actually get a lot of questions from the listeners.

I think we've had three or four different times where we've had this question, like why does our immune system get worse when we get older?

Like why is a virus that was maybe good initially bad later on?

Like we've seen so many new things as we get old, Like we've seen a bunch of viruses, a bunch of bacteria infections.

Why doesn't that make our immune system stronger as we get.

Older, wiser?

Yeah, with a deeper library.

So many things, so many different metaphors we could layer on this thing.

I think probably the short answer is it's just harder to do everything as a body as entropy kicks in, whether that's your immune system or other things.

Right, So, like we shouldn't give a special category to the immune system just because, right?

What do I mean by that?

Though?

So?

Like we know, for example, that when you're younger, you're better at suppressing a latent herpes infection from having an outbreak, you know, and when you get older you get less good at that.

Shingles is a really good example of this, you are far more likely to develop shingles, which is again a latent infection that then runs rampant when you're older than when you're younger.

So that's that immune system failing to tamp down on that virally infected cell going nuts and spreading that around, right, And I think I think some of it is just cells get worse at replicating them cells, you know, as they go further along in their many replicated lifespan.

You know, when you look in a mirror at one of those fun houses and like there's a bunch of mirrors and it makes that infinity mirror effect, so you have an infinite number of views.

But like you start looking not great if you really look back at the like far distant, you know, like there's image loss of you, Like there's info loss, is what it really is.

And cells have info loss over time too.

Basically, they get less good at correcting for errors the more they've been replicating over a body's lifespan.

And as far as we know, the immune system does that too.

But to speak to Dan's instinct here, as he already mentioned, it's probably pretty complex.

That's actually a pretty simplistic explanation for why aging sucks for all cells throughout the body.

And actually it's probably a lot of different things.

That's super fascinating.

I've always been curious about this story of mitochondria coming from the outside and then getting sort of incorporated.

You're telling me that's a real story.

Well, it's as real as science is able to make it real without a time machine.

But yeah, like, there is this idea that once upon a time there were cells.

Like, the cells have a lot of different organelles in them.

Cells are full of stuff.

You've probably seen a diagram, right, yeah, okay, Well, mitochondria are the energy powerhouses of your cell basically, and they're their own little independent organelle.

Interestingly, they have their own DNA m DNA, your mitochondrial DNA, which is separate from the DNA in the nucleus.

So that's your first clue that something's up.

Not all the organelles in your cell have their own DNA, you know, it'suff like, hmm, what's up there?

Why do you got your own?

Right?

So that's part of it.

But also it seems generally that once upon a time, either a cell tried to eat another, you know, being in the soup of ancient world and or actually the mitochondria tried to infect you know, protobacteria like we're not really sure a cell and then failed to die and or eat the cell it was trying to eat.

We don't know which direction.

We don't know who was eating who.

Here as the point, but somehow, one one dude, one cellular dude ended up inside of the envelope, the cellular envelope the membrane of another one, and somehow didn't die and zombie like.

That became a mutual relationship, right, and over time it became a basic part of how basically all cells go about their cellular lives.

Right.

That so effectively your mitochondria and your cells are replicating in an interesting way when each cell goes through the process of replicating itself, right, hence the separate lineages of DNA.

Wow.

Now, one of the really cool things about this is that also means that this is yet another reason why sperm don't do a lot so well sorry, sorry, uh.

You know that nearly all of your mitochondrial DNA is coming from your mom.

That's coming from the egg, right, And that's why eggs are so huge and sperms are like a tiny little like you know, Twitter feed, a tiny little note of information with a tail.

You know that just somehow has to get there.

Because when a sperm you know, decapitates itself, basically drops off its tail and goes inside the egg, you know, it is then eaten.

It's eaten by the egg basically and then you know, hence baby, the miracle of life.

But usually the egg just completely destroys all the mitochondria from that sperm.

It's like nope, nope, nope, no nom nom you out right.

But we now know because unfortunately, some people have issues with their mitochondria that gives them certain kinds of infertility or developmental problems.

There are disorders that can come with mitochondria.

Basically that every now and again, sperm mitochondrial information actually do manage to escape the death spree that is going inside of an egg.

Yeah, yeah, yeah, Because this is an IVF thing, right, The idea is like, well, can you simply get rid of the mitochondria from the sperm or what have you, or from the egg and then just replace it and we solve all of our mitochondrial disorders thereby.

Wouldn't that be awesome?

It would be if only it were a perfect system that it's never the case that the sperm mitochondria actually make their way in.

So again, biology.

Sloppy, super sloppy.

It's a delicious mess.

I don't know if it's delicious.

What I always find kind of chalky.

Hmm, go ahead.

So when when the sperm mitochondria stick around, what is the problem.

Is it just that they're interfering with each other or the sperm mitochondria is like deficient in some way, like would do we know what causes the problem there?

I don't think it's the case that sperm mitochondria are just so janky that let's just not although I'm amused by that idea that somehow they're just like the worst option.

No, I think I think it's actually that they've set up their mitochondrial system in that egg.

The they that is the collective which is an egg, and it's many organelles, you know, and they just don't want to like throw some new shit in the mix, as it were.

So that's the general theory that basically it's controlling for error to not have that be And this is part of how you you trace the so called mitochondrial eve.

You're actually tracing the mitochondrial inheritance over many generations to say who is the last being from?

Whence most of our mitochondria come from?

Incredible?

All right, well let's see if we answered Petre's question.

Thank you Kelly and Daniel for choosing to answer my question on the show, and thank you especially to doctor bo Henson for your wonderful answer.

I realized that this is an incredibly difficult question that goes way back into deep time, and ideas of what is beneficial versus not beneficial certainly get muddled quite quickly.

But your answer was fascinating and enlightening.

I also appreciate that you took the time to address the other question of mitochondria DNA.

That is something that's intriguing for me and I'm sure for many of the other listeners.

So once again, that's a great answer.

Thank you so much.

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