Listener Questions #23

Daniel and Kelly answer questions about fingerprints, particle beam accidents, tickles and yawns!

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:07):
Our fingerprints actually all unique?

Speaker 2 (00:11):
Are we sure they never change? I'm not contemplating committing
a crime. I just find it strange.

Speaker 3 (00:17):
A Russian man was once bitten by a particle beam.
If you injected a parasite intocern, would it turned into steam?

Speaker 1 (00:26):
I read about someone yawning.

Speaker 2 (00:28):
Now I have to do it too. I promise on
that board. It has nothing to do with you.

Speaker 3 (00:35):
Being tickled is something I absolutely hate, So then why
do I laugh when it makes me so irate?

Speaker 2 (00:42):
Whatever questions keep you up at night? Daniel and Kelly's
answers will make it right.

Speaker 1 (00:48):
No, I'm gonna spend the whole time, Yati.

Speaker 3 (01:03):
Hi, I'm Daniel. I'm a particle physicist, and I really
don't like being tickled.

Speaker 1 (01:07):
Hello, I'm Kelly Waiter Smith.

Speaker 2 (01:09):
I study parasites and space, and I don't mind being tickled.

Speaker 1 (01:13):
It's okay, I guess.

Speaker 3 (01:15):
But I do love giving a good tickling, which makes
me a terrible hypocrite.

Speaker 1 (01:18):
I know, you know.

Speaker 2 (01:21):
One of one of the great joys in my life
is that my son loves being tickled, and he has
the greatest smile and the best laugh. And I know
that I'm biased, but like he wakes up in the morning,
and the very first thing he says is tickle. Like
just while he's getting his like brain together and clearing
the cobwebs, he knows he wants tickles already, and so

(01:42):
he always wakes up asking for tickles.

Speaker 1 (01:44):
And and I love that.

Speaker 3 (01:46):
Well, I don't like being tickled, but I love the
idea of tickling. You know that it shows you this
deep like mind body connection. Somebody just has to like
wiggle their fingers at somebody who's ticklish, and they erupted laughter.
It's crazy, right, It shows you that like our mind
and our bodies are deeply, deeply connected.

Speaker 2 (02:05):
Yes, yeah, And we can even just say words to
our son that imply we're about to tickle him, and
he'll start like squirming and giggling because he knows it's coming.
And yeah, it's fun.

Speaker 3 (02:16):
And what tickles me the most are the puzzles of
the universe, how everything works, what it's all made of,
and how it all comes together. And I love being
tickled by our listener's curiosity everything that you all wonder
about the universe.

Speaker 2 (02:29):
You're so good at that, Daniel. All right, and so
let's jump right to our first question. And our first
question is a question that we got from our amazing
Discord community. We have the best moderators on that community,
and if you want to join us, you can find
an invitation to our Discord group at Danielankelly dot org
and we would love to see you there. So let's

(02:50):
go ahead and hear our first question from Albario b X.

Speaker 4 (02:55):
Hello, Daniel and Kelly, this is Alberio BX, but you
guys can just call me true if it's easy use.
I was thinking about the human body and how much
it changes over the course of its lifetime. I even
heard of statistic that every seven years or so the
human body you have a completely new set of cells.
I don't know if that's true or not, but I
hear that statistic quite often. However, from womb to tomb,

(03:19):
our fingerprints remain the same. I was wondering why that is.
Why is it that our fingerprints never change? Is that
something that's encoded in our DNA. If I get a
paper cut and my finger does the DNA tell the
cells how to regrow into that fingerprint? I was also
wondering does everyone truly have a unique set of fingerprints?

(03:44):
Is it possible to be born where you have a
matching right index finger with a completely random person. What
are the chances that you might actually have the same
fingerprint as someone else? Very curious about that. Thank you
very much in advance. I'm looking forward to hearing your answer.

(04:04):
I love the podcast and shout out to the Discord community.

Speaker 3 (04:08):
This is awesome because I have the same question. I've
always wondered this, and now we have an excuse for
Kelly to go do a bunch of research and answer it.

Speaker 5 (04:16):
Yay.

Speaker 2 (04:17):
What I love is that I hadn't actually ever wondered
what forms my fingerprints? Why do they form? But then
we get so many questions from our listeners where I'm like, oh, yeah,
what does that happen? So like, props to y'all for
being way more curious than I am and for helping
me get the answers to these sorts of questions.

Speaker 3 (04:37):
So let's start with the basics, like why fingerprints? Why
do I even have them? Why aren't our fingers smooth?

Speaker 2 (04:43):
So we think that we have fingerprints because the extra
surface area that they create helps us grip things better. Really,
so like those extra ridges help make it easier for
us to hang on to things. Or maybe those extra
ridges give us like more surface area that can connect
with things, and so we have higher sensitivity because we're
essentially touching things with more skin. I don't think we

(05:07):
actually have this answer like locked in. I wouldn't bet
my life.

Speaker 1 (05:12):
On that answer.

Speaker 2 (05:13):
But our great ape ancestors also have fingerprints, so this
is like an ancient thing that came about a while ago.

Speaker 3 (05:21):
Yeah, I'm not deeply impressed by these ideas. I mean
they sound to me like reasonable first hypotheses as you're
investigating it. But you know, having people done experiments like
does it actually give you better grip? Does it actually
make you more sensitive? Do we know any of that.

Speaker 1 (05:37):
I didn't read about that part for very long. I'm
mostly read about why how we got our fingerprints.

Speaker 2 (05:42):
That's a great question though, And if you are unconvinced
by these answers, wait until you get to yawning and
tickling later.

Speaker 1 (05:48):
On in the show.

Speaker 2 (05:50):
The answers only become less convincing as we go today.

Speaker 3 (05:54):
Well, this just shows you how deep a puzzle all
of biology really is. There are so many amazing me
to solve and mysteries along the way. All right, So
then if we don't really know why we have them?
Do we understand how they form?

Speaker 1 (06:08):
Yes? So okay, all right, so here we go.

Speaker 2 (06:15):
All right, so will we are fetuses and we're starting
to develop. This is very early in like the first
first couple months, like first trimester, maybe started the second.

Speaker 3 (06:26):
All right, I'm a fetus. I'm floating around.

Speaker 2 (06:28):
Yep, floating around in an amniotic sac and your fingers
on the tips you get these things called volar pads.
And when I saw a picture, they remind me of
like the sticky section cuppy bottoms on gecko feet.

Speaker 3 (06:41):
Cool.

Speaker 2 (06:42):
And so you get these like, you've got these pads,
and these pads are going to eventually sort of become
part of the rest of your finger, and so they
will like sort of get integrated into your skin. And
so the shape and location of these pads on your
finger or what's ultimately going to determine whether you get whorls, loops,

(07:07):
or arches, the three main shapes of fingerprints.

Speaker 3 (07:11):
But how big are the pads relative to like the
tip of your finger. I was originally imagining like one
big pad, but sounds like it's a lot of little pads.

Speaker 1 (07:19):
No, So each finger has one big pad.

Speaker 3 (07:23):
Yeah, so then how to the location of the pads
or the orientation or something determine whether you're getting loops
or whorls.

Speaker 1 (07:29):
Well, I'm gonna get there, my friend. Okay, I got
to give me a second, all right.

Speaker 2 (07:35):
The background with these pads, though, is that where you
have these pads in their shape is sort of genetically determined.
So this is why, and what we'll get to why
in just a second. But this is why families sometimes
have similar main shapes for their fingerprints. I didn't know
that either until I started researching this. But they will
still have unique fingerprints.

Speaker 3 (07:55):
Okay, Okay, so you could like deduce familial relationships just
from fingers.

Speaker 6 (08:00):
I don't.

Speaker 2 (08:01):
It is the case that you can look at the
fingerprints of family members and they will be similar, but
I don't know that that is a reliable enough indicator
that you could say, oh, Daniel's brother committed the crime
because we've been able to see Daniel's fingerprint and this
fingerprint looks really similar.

Speaker 3 (08:17):
Well, I was wondering if anybody'd ever use them for
like paternity tests like that. Can't be my baby. It's
got whirls and I've got loops or something.

Speaker 2 (08:24):
No, I think it's not quite that informative. All right, interesting, Yeah, yeah,
it's more like a ndo fact that your family is
like a whirl family instead of an arch family or
something like that.

Speaker 3 (08:35):
I don't even know. I got to go find out
a minute.

Speaker 2 (08:37):
Okay, Well there you go. And this had me spending
a lot of time looking at my fingers.

Speaker 3 (08:41):
But uh, I was just staring at my own fingers.
All right, So tell us how they form?

Speaker 1 (08:45):
All right, So your voler pads.

Speaker 2 (08:47):
They're on the tips of your fingers, and they are
becoming part of your skin. So your skin. Let's talk
about three layers. You've got the epidermis, which I'm just
gonna call the outer layer. You've we got an inner
layer called the dermis, and I'm gonna call that the
bottom layer. And in between the epidermis and the dermiss,
you have this middle layer, transition layer that we call

(09:10):
the basil layer, but I'm just gonna call it middle.

Speaker 3 (09:13):
The middle one is called the basil layer.

Speaker 1 (09:15):
All right, yes, but middle from here on out.

Speaker 3 (09:17):
Okay, I'm gonna hold my fire here on criticizing biological names.

Speaker 1 (09:22):
That would be fair.

Speaker 2 (09:24):
I mean, it's basil to the epidermis, but all right, anyways.

Speaker 3 (09:27):
Save with like a skin sandwich, let's just review. We
got the dermis in the bottom, the middle layer, and
then the epidermis on the outside.

Speaker 2 (09:34):
Yes, right, okay, So the bottom layer, the dermis, starts
replicating much quicker than the top layer. And as it's
replicating more and more quickly, that middle layer starts to buckle.
And when that middle layer buckles, that's what's going to
form the ridges that you see on the outside of

(09:55):
your finger. And the location of the volar path impacts
where those buckles happen, because it's sort of like you know,
bending around that volar pad, and so like where your
volar pad is located. Any like differences in a shape
between individuals will impact if you get the whorls and
stuff like that.

Speaker 3 (10:15):
So the bottom layer is growing faster, and the top
layer is into the top layer like cracks, and so
essentially the topic of your skin is sort of like
incomplete and you can sort of see down into the
other layers, is that right?

Speaker 1 (10:27):
Kind of?

Speaker 2 (10:28):
So, so the bottom layer is replicating like crazy, and
then the middle layer is the one that's buckling, and
that's going to stay buckled essentially the way it's forming
right while you're a fetus for the rest of your life.
And then from that buckled layer, your epidermis emerges, and
it reflects the buckles that are happening in that middle layer.

Speaker 3 (10:48):
And why are the buckles often in lines? Why aren't
they like moor in patches or blobs.

Speaker 1 (10:53):
So a couple things.

Speaker 2 (10:54):
First, I think that has to do with the way
that they grow around the volar pad. But then also
the lune lines sort of show up in a pattern.
So first they start so they start growing in the
center of your finger, and then some of the lines
start emerging on the tip of your finger, and then
heading towards the middle. And then where the top of
your finger bends for your first joint, there's lines starting

(11:18):
there too, and more moving towards the center. So there's
three spots the line start the middle, the top, and
the bottom, and the top is moving towards the bottom,
and the bottom is moving towards the top.

Speaker 3 (11:27):
And it sounds like there's some sort of stochasticity here,
like the same fetus if you ran the experiment ten
times might end up with slightly different fingerprints.

Speaker 2 (11:34):
Yes, so this reminded me of when you were talking
about how snowflakes are formed, and you were talking about
how as you move through a cloud, the little micro
features of the climate, so like it's a little bit
colder here, a little bit wetter here, like that creates
a unique fingerprint. So your fingerprint apparently can be impacted
by things like how thick the amniotic fluid is while

(11:56):
your fingerprints are forming, and so there's a bunch of
randomness at this stage that impacts the details of your fingerprint.
And the way these details play out are things like
when lines come together and they form, do they join
or do they kind of form a branching pattern. So
you've got like short ridges that are just kind of

(12:17):
like a little bit of a line that doesn't really
go anywhere, or an island which is just like a
little spot where there was a buckle, and it also
doesn't really form a line like you would expect. And
there are many, many, many of these unique features on
our fingers, and so looking at places where your finger
forks or where you have an island, and then looking

(12:38):
at the relative location of those features relative to one
another creates so many possible combinations that there's more combinations
than there are humans.

Speaker 1 (12:47):
On this planet.

Speaker 3 (12:48):
Probably a lot more, right, Yeah, a lot.

Speaker 2 (12:50):
More, a lot more. And so that's why every fingerprint
is unique. I suppose it's not impossible that two people
could have nearly the same finger It's just really vanishingly
small probability that even within your family, when you've got
the same like patterns of loops and whirls, that all
of this would come together in the exact same way

(13:10):
is statistically improbable.

Speaker 3 (13:13):
It's like rolling a die with a zillion sides twice
and getting the same number.

Speaker 1 (13:18):
Yes, exactly right.

Speaker 3 (13:19):
Wow, so your fingerprints really are a unique identifier.

Speaker 1 (13:23):
Yes, yeah, they're really unique identifiers.

Speaker 2 (13:27):
And then the listener wanted to know why don't our
fingerprints ever change? And the reason they never change is
because you know that pattern is emerging from these.

Speaker 1 (13:36):
Buckles, and those buckles in this.

Speaker 2 (13:38):
Middle layer will always stay the same as you get older,
and so if you cut your finger, it will grow
back and reflect those buckles that happened while you were
a fetus. So I mean, if you like cut your
finger open and it, you know, grows back in between,
like maybe you'll have a cut in the middle of
your fingerprint or something like that. If you have a
scar there but in general, any minor cut that you have,

(14:00):
your skin should grow back with the same pattern, reflecting
what's happening in the buckled layer below.

Speaker 3 (14:06):
So for anybody out there who's pregnant, how far into
the pregnancy are the fingerprints determined? And does it happen
like over a day or a moment, or like a
week or depend on what they're eating for dinner.

Speaker 2 (14:19):
I think it happens between ten and sixteen ish weeks
post conception, so it takes a little while. It's not
like you can have a spicy burrito if you really
want worlds and a bag full of carrots, if you'd
like a child with arches.

Speaker 1 (14:35):
You know, you don't have that kind of control.

Speaker 3 (14:37):
But that's really amazing to hear that your fingerprints are
essentially determined when you're pretty small, I mean ten to
sixteen weeks, you're like, what the size of a walnut
or an orange.

Speaker 1 (14:46):
Or something pretty small? Yeah, I don't know exactly.

Speaker 2 (14:49):
I definitely when I was pregnant had that app that
every week would like pop up a new fruit to
be like, your daughter is a mango. Now it's like,
oh delicious.

Speaker 3 (14:57):
I remember when our firstborn son was a lent Kachin
was like, oh, our little lentil.

Speaker 1 (15:03):
Oh, that's so cute.

Speaker 2 (15:05):
I think peanut popped up once and we've called our
daughter peanut ever since, and uh, I don't think that's
her favorite thing.

Speaker 3 (15:13):
Funny how some of those things are cute and affectionate,
but nobody wants to get called an avocado.

Speaker 1 (15:18):
Yeah, yeah, that's right, that's right.

Speaker 2 (15:20):
Here you banana, my little grapefruit.

Speaker 1 (15:27):
That's right.

Speaker 3 (15:27):
Yeah, it just doesn't work, just doesn't work. Some fruits
are more emotional than others. All right, fascinating, Well, thank
you very much of that answer. Let's send it back
to Albiro and see if we have answered their question.

Speaker 6 (15:40):
Wow, thank you so much Kelly for the insightful answer,
and thank you Daniel for asking such insightful questions. It's
mind blowing to me that genetics does play a role
slightly in determining what type of fingerprints you have. But
what's even more mind blowing to me is that the
condition of the womb plays a role in a type
fingerprints you have. To me, that makes it obvious that

(16:03):
everyone's going to have a unique fingerprint, because statistically, what
are the chances of replicating everything perfectly. It's not going
to happen, not naturally at least, so that answers that
question perfectly. Thank you guys so much for the insightful answers.
I really really appreciate it, and I am looking forward
to the rest of the episode.

Speaker 3 (16:43):
Okay, we're back and we're answering questions from listeners today.
Here's a question from a listener who's curious about particles
and parasites.

Speaker 7 (16:52):
Hey, Daniel and Kelly, I love the show, and I
love that biology has been getting some coverage lately. In
the episode about leech Is, Daniel mentioned that he's never
been bitten by a particle, but I heard about an
incident where a Russian physicist sort of was attacked by
particles when he got part of his head accidentally in
the proton beam of his particle accelerator and he lived

(17:16):
to tell about it. So to me, this brings up
so many unanswered questions, such as, are these beams just
in open air so that you can go up and
touch them, what they look like? And does CERN have
a proton beam that's similar to this, and what color

(17:36):
would it be? And if you went and opened up
the hatch at CERN, that I assume you have and
you just like reached in there and grabbed the beam.
What would happen? Or if you tried to intercept it
with different materials, like you put glass in front of it,
or try to reflect it with a mirror, or stuck
some of Kelly's parasites in there with a long pair
of tweezers? What would happen in those cases? For considering

(18:00):
my question, and please don't let this physics question stop
you from talking about parasites.

Speaker 3 (18:06):
Thanks.

Speaker 2 (18:07):
I love that this question managed to sort of shoehorn
parasites in it. Maybe wasn't a natural melding of topics,
but anytime.

Speaker 1 (18:17):
Parasites can be worked into a conversation up games. So
thank you Ryan.

Speaker 3 (18:21):
And this is a great opportunity to tell a really
fascinating story in the history of particle physics and also
a tragedy. Of course, this is not an apocryphal story.
There really was a Russian physicist who was zapped by
a particle beam. Nineteen seventy eight. Anatoly Burgoski was working
at the U seventy accelerator in Protvino. U seventy was

(18:44):
called because it was able to accelerate protons up to
about seventy giga electron vaults, which at the time was
really impressive. These days, our accelerators are much more powerful.
So one giga electron volt is about the energy in
the mass of a proton, So seventy gig electron volts
means you've given it kinetic energy seventy times its mass,

(19:05):
which is a lot. But the Tabotron where I got
my PhD in, which for a while was the highest
energy collider in the world, is almost two thousand GeV,
so much more powerful, and the Large Hadron collider is
almost fourteen thousand GeV. So these days colliders are much
more powerful than back in the seventies. But this still

(19:25):
was a lot of energy for a person to absorb.

Speaker 2 (19:28):
Yeah, so whatever we're about to hear happened to anatolely,
we could imagine it would be way worse if it
happened to someone today exactly.

Speaker 3 (19:36):
And so what happened was Anatoly was working on the collider,
and people often imagine that he like stuck his head
into the beam, And I think that's part of Ryan's question,
is like, how do you even get into the beam?
How does that even happen like, isn't there a pipe there?
And it's a good question because that's not really possible.
Usually these beams are in vacuum because you want the
beams to go fast and to not collide with air particles,

(19:58):
and so usually a beam pipe and pump it down
to near vacuum. For example, at CERN, the beam pipe
is like ten to the minus eleven atmosphere. And that's
because we want just proton proton collisions, not proton air
collisions at some random place. And so that also was
happening at the U seventy sygnotron. But sometimes you take
the beam and you bend part of it off to

(20:19):
slam it into some other kind of target. Maybe you
want to smash it into some crystals, or you want
to hit it into some high density target and look
for other kinds of interactions. And so they also had
this feature at the U seventy signatron. It is like
a beam extraction channel where the beam is like bent
off and directed at a target. And so the beam
was supposed to be off and he was like working

(20:40):
on the target and he was leaning over some equipment,
and the safety mechanism which prevents the beam from coming
on when people are working on it failed and so
the beam cranked back up and some of it shot
out this beam extraction channel and instead of hitting the target,
it went right through his head. Oh, no, bad news.

Speaker 1 (21:00):
Did he immediately know that that it happens?

Speaker 3 (21:03):
He immediately knew. He described it as seeing a flash
brighter than a thousand suns, but weirdly felt no pain. Right,
He didn't like immediately feel burned, though he didn't actually
get burns on his face. Right. What happens when particles
impact flesh is they deposit a lot of energy. Basically,
it's cooking you. Right. We talked about this in our
episode about how particle beams can cure cancer. If you

(21:26):
deposit energy just into the tumor, for example, you're cooking
the tumor. And proton beams are really good for this
because they tend to deposit their energy yet only a
certain depth. Depending on their energy, they either dump it
one centimeter in or two centimeters in or four centimeters in,
so you don't have to like a radiate a whole
tube of flesh. You can actually just irradiate a little
deep blob. So protons are the particle of choice for

(21:48):
treating cancer and it only didn't have cancer, but he
did get this proton beam through his face, and everyone
expected him to die. Basically, they took him to the
hospital to say, like, okay, let's watch what happens to
see when but he dies from protons. But he didn't.
He recovered. Wow, his face was half paralyzed. He lost
hearing on that one side. Amazingly, the paralyzed side of

(22:11):
his face didn't age. What So like one side of
his face is like still smooth and the other one
is getting wrinkles. I guess maybe because he like can't
move it, so like the skin isn't getting wrinkled. The
dude is still alive. He's like still around.

Speaker 7 (22:25):
What.

Speaker 3 (22:25):
Yeah, this happened in nineteen seventy eight. He was born
in forty two, so you know he's getting up there,
but he's living a long life.

Speaker 1 (22:33):
If the protons are depositing all of their energy in
a very particular spot, do we know, like was it
in his occipital lobe where the hippocampus or like, do
we know what region it deposited all of its energy in.

Speaker 3 (22:45):
Well, it's actually really fascinating because proton beams we used
to treat cancer typically are much lower energy, like much
less than a GV, so that they do this thing
where they stop and they deposit all of their energy.
So in this case, because they're so high energy, probably
most of them just went through him. Okay, right, so
he didn't get the like major deposition. In that sense,
a higher energy beam might be safer because these protons

(23:07):
don't end up dumping all of their energy, but they
also have a lot of energy, so even if they
lose a little fraction, you're getting fried. So yeah, it
probably damaged a whole tube of Russian physicists through his brain.

Speaker 2 (23:19):
Yikes, he's so lucky that he's not lucky at all.
He's very unlucky. But the fact that, I mean, based
on the explanation so far, doesn't sound like, you know,
he's forgotten his loved ones or he can't move his
right foot anymore. Like, it sounds like he got off
pretty easy. Given what he went through. I would have
expected this to have been much worse.

Speaker 3 (23:39):
Yeah, apparently he still has like occasional seizures, so there
are lingering brain effects, but you know, he's still being
a physicist. He's got his brain mostly there.

Speaker 1 (23:47):
So wow.

Speaker 3 (23:48):
Yeah, it's incredible, and in principle this is something that
could happen at CERN. Again, not with the main beam,
because there's no way to access the beam when it's running.
They can't run the collider until they close the beam
pipe and they pump it down to vacuum and then
they turn the collider on. But there are also fixed
target experiments at CERN where they take part of the
beam and they divert it off somewhere else and they

(24:10):
should add like a dense block of material to create
neutrinos or muons or something else. There's of course a
lot of safety equipment involved, but there are places where
the beam is not in that beam pipe, and so
in principle one could. Now Ryan wanted to know what
would happen if you stuck your eye in the beam
at CERN. It would be very, very bad. It's definitely

(24:31):
not recommended. I mean, at CERN we have more than
two hundred times as much energy per proton as in
the Burgorski accident, so much higher energy per proton. Also,
the thing we've done at the Large je On Collider
is we've made the beams more intense, which means a
lot more protons. The beams are not like continuous, which
just like proton proton proton proton proton, they come in

(24:52):
these bunches of like ten to the ten protons, and
you pass the bunches through each other. And the goal
there is to get as many interactions as possible. So
you make the bunches really tight and dense, and you
pass them through each other after you focus them. So
we have much higher intensity beams, like more protons per second,
not just more energy per proton, and we overlap these

(25:12):
bunches every twenty five nanoseconds. So yeah, these beams are
very intense and much more dangerous than with the head
back in the seventies.

Speaker 1 (25:20):
So really be extra careful.

Speaker 3 (25:23):
Really be extra careful. Now, if you really are not
a fan of parasites, you really wanted to fry a parasites,
or you wanted to make a parasitologist, you know, uncomfortable,
you could tak a parasite, put it on a stick
and stick it in the beam, and yeah, there would
be a lot of energy deposited into that parasite very quickly.
You would have a roasted or toasted or something parasite.

Speaker 2 (25:45):
All right, there are some parasites that ought to be
roasted or toasted, so I can accept I can accept this,
although it seems like an inefficient way to take out
a population of parasites.

Speaker 3 (25:54):
I wouldn't mind some mosquitoes getting fried by those beams,
and I wouldn't mind having like some sort of beam
I could shoot at mosquitoes. I recently saw this ai
which has a camera and it spots mosquitoes, and it
shoots a laser at the mosquitoes, but just to identify
them so you can then go zap it. And I
was like, oh, soup that thing up. Man, fry those
mosquitoes like Star Wars space based weapons to fry mosquitoes

(26:17):
from space. I'm all into that.

Speaker 2 (26:21):
But then I guess you have to worry about it,
Like if the mosquito is in front of your face,
isn't gonna is the laser gonna hurt you?

Speaker 1 (26:27):
If it hits you too, I'd.

Speaker 3 (26:29):
Rather the mosquito get fried and I get a little
bit of splash back then get bitten. All right, But
we're gonna do a whole episode about mosquitoes pretty soon,
aren't we.

Speaker 1 (26:38):
We sure are.

Speaker 3 (26:39):
And I'm imagining that Jewish space lasers are not a
part of the solution too.

Speaker 1 (26:45):
That wasn't on my research list.

Speaker 3 (26:47):
No, it was all right, So let's send our answer
back to Ryan and see if we have answered his question.

Speaker 7 (26:54):
Daniel, thanks for that info. I didn't know the beam
could be diverted outside its normal chamber. Didn't necessarily mean
that you stick your eye in the beam. More like
what it would look like from the side view. I
kind of imagined it looks like a laser, but I
have no idea.

Speaker 3 (27:09):
Hey, Ryan, great follow up question, and your intuition is
exactly right here. The beam would look a lot like
a laser, which is invisible unless you see scattered dust particles.
The beam is going through a vacuum and so almost
nothing gets scattered, and so it's essentially invisible.

Speaker 7 (27:26):
Thanks for the info, and thanks for such a good podcast.

Speaker 6 (27:48):
All right.

Speaker 2 (27:48):
Next up, we have two questions that were sort of
along a similar line. I think they were both inspired
by our episode on why do we itch? And they
got folks thinking about other questions why do we yawn?
Why are we ticklish? And so let's go ahead and
listen to the questions from Jude and Dylan.

Speaker 8 (28:08):
Hi, Daniel and Kelly, I love your show. Your recent
response to the question about itching got me thinking, what
causes tickling? Why do we involuntarily laugh when tickled? Is
it learned a behavior that becomes conditioned?

Speaker 6 (28:22):
Hi, Daniel and Kelly.

Speaker 5 (28:23):
It's Dylan from California, and my question is about yawn's.
When I was younger, I heard that when you see
somebody yawn and it makes you yawn, it's due to
a sympathetic response somewhere in your brain. And I guess
that kind of makes sense, but it doesn't really account
for the fact that when I talk about, hear about,
or think about yawn's, it often makes me yawn.

Speaker 6 (28:43):
So I hope to hear what you guys have on
the subject.

Speaker 2 (28:46):
Well, Daniel, the answer to both of these is, uh,
we don't really know, and so I thought I would
sort of smooth them together and tell you what we
do know, and then you know, highlights are lack of knowledge.

Speaker 3 (29:00):
Is this going to be a very short answer?

Speaker 1 (29:03):
No, I tried.

Speaker 2 (29:04):
I tried to dig pretty deep to see what we
did know, so hopefully hopefully you learn something.

Speaker 3 (29:08):
All right, Well, let's start with tickling, okay, because otherwise
we'll all be yawning.

Speaker 1 (29:11):
That's right.

Speaker 2 (29:12):
Yeah, Well, we'll end the episode on the Yawner so
that everybody can go take a nap afterwards. So did
you know, Daniel, that there are two kinds of tickles?

Speaker 3 (29:22):
Only two? Well, I have in my power several kinds
of tickles.

Speaker 2 (29:26):
Oh oh interesting, wow, Well scientifically maybe you should get
into this field. Scientifically, there's two. There's knnis messis. I'm
sure I got that wrong, But did you want to
try it? You could see it written down.

Speaker 3 (29:42):
I was gonna sayis misis.

Speaker 2 (29:44):
But kennismesis maybe sure. It's the Greek word for itching.
And essentially this is like a sort of light, feathery sensation.
It actually sounds quite a bit like itching, which is
to say, you just sort of gently run like your
fingers along the surface of somebody's skin and it doesn't
necessarily make them laugh. Maybe it feels kind of nice.

(30:06):
It feels like maybe there's a spider walking on your skin.
And so I think we suspect that the function of
this kind of tickle is because it helps you identify
if something is walking on your skin. It draws your
attention and then you like press the spider, or you know,
you brush the spider or the tick away.

Speaker 3 (30:21):
But it's different from the feeling of an itch.

Speaker 2 (30:24):
I think there's a lot of overlap here. Itching is
often self initiated. So for example, we were talking about
how different aspects of our immune response can make you itch.
So that's something inside of your body that is resulting
in an itch. This is specifically in response to external stimuli,

(30:44):
and I think that's part of the difference.

Speaker 1 (30:46):
But it did seem to.

Speaker 2 (30:47):
Me while I was researching it that there's probably a
lot of overlap there.

Speaker 3 (30:50):
So, like a spider is crawling along the hairs in
the back of your arm, that's going to make you
feel a little ticklish, and your finger's going to go
over there and be like.

Speaker 2 (30:57):
Yeah, yep, yep, And I'm going to spend the rest
of the episode now scratching and thinking that certainly there's
something crawling on me. After I get a tick on me,
for the next couple of weeks, I spend the whole
time being like, there's another one, and there's not another one.

Speaker 3 (31:09):
All right. So if we're recording an episode and I
see a spider crawling on your shoulder, what do you
want me to do?

Speaker 2 (31:14):
Hypothetically speaking, Well, you know, if I felt like you
could identify it if it were a black widow or
a brown recluse, i'd want you to say something. Otherwise,
let it go. It's probably fine.

Speaker 1 (31:26):
Yeah.

Speaker 3 (31:26):
I have a friendly relationship with spiders because we both
hate mosquitoes. Right, So I'm like, yeah, you want that
corner in my bedroom, you can have it. As long
as you eat any mosquito that comes near you. That's
the deal.

Speaker 1 (31:36):
Yeah.

Speaker 2 (31:36):
No, I mean, I in general like the spiders on
my property. I think they do a nice ecological service.
I am just a little nervous of the ones where
if I get in their way they could hurt me.

Speaker 1 (31:46):
Yes, But otherwise I love having them around.

Speaker 2 (31:48):
And actually our property has tons of rabid wolf spiders.

Speaker 1 (31:53):
Wow, which sounds really bad.

Speaker 2 (31:56):
Yeah, but they're not and they're they're fine, And they
walk around on the grass. And if you go outside
with the headlamp, which I do sometimes in the middle
of the night, there are literally thousands of little green
lights that are like reflections in the eyes of the
spiders coming.

Speaker 1 (32:12):
Back at us. And I'm like, oh, there's a lot
of you guys out here. I'm not gonna think too
hard about that.

Speaker 3 (32:17):
This is the script of a horror movie.

Speaker 2 (32:19):
Yeah, but you know, I like them. They control the
other kinds of insects. We're good the rabbit wolf spiders
and I are good.

Speaker 3 (32:25):
But okay, you go outside and there's thousands of little
friendly spiders going. Don't worry, Kelly, we're on it. We're
patrolling for insects.

Speaker 1 (32:32):
And I say, thanks, buddies.

Speaker 3 (32:35):
Okay, all right, so tell us about the other kind
of tickling.

Speaker 1 (32:39):
All right, the other kind of tickling.

Speaker 2 (32:41):
So we all know at this point to never expect
that I'm going to pronounce anything correctly, So don't repeat
this to anybody you want to look good in front
of I think it's gargelesis.

Speaker 1 (32:53):
And this is the more intense kind of tickling.

Speaker 2 (32:56):
This is probably the kind of tickling that Daniel is
telling us, who's really good at where you're pressing down
kind of hard. It's like a rhythmic motion and it
makes people laugh.

Speaker 3 (33:06):
Yeah, but you've got to be moving fast also, right, Yeah, you.

Speaker 1 (33:09):
Got to be moving pretty fast.

Speaker 2 (33:10):
And so we're, to be honest, not one hundred percent
sure why quickly pressing down on somebody's body results in
this feeling of ticklishness and why it makes you laugh.
We think pressure receptors are involved, but we don't necessarily
know why. When you hit pressure receptors in some part
of the body it makes you go and in other

(33:31):
parts of the body it just kind of hurts.

Speaker 3 (33:33):
When you say why, are you saying we don't understand
like the mechanism, like we can't explain how the signals
propagate and do the thing. Or are you saying why
in the sense of why does it make sense to
do this? Like evolutionarily? Is this an advantage for some
reason or the byproduct of some other system, or is
it both kinds of why?

Speaker 1 (33:53):
Both?

Speaker 2 (33:54):
But there's a couple of hypotheses for why from an
evolutionary perspective, So let's go ahead and chat some of those.
So one of the ideas, and I got to say,
I don't find this one super convincing, is but it
was in a lot of the papers that I read.
So one of the ideas is that tickling teaches you

(34:14):
to protect vulnerable areas. So like when your parents tickle you,
they're teaching you to the like, tuck your arms into
your side because if someone I don't know, if someone
like stuck a sword in your armpit, they could like
they could hurt you. But I feel like there's other
parts of your body that you wouldn't want to get
slashed open that aren't super ticklish. And I guess I'm

(34:35):
just not convinced that someone tickling me would prepare me
for like a lion coming and attacking and now I'd
suddenly like I'd cover my stomach so it wouldn't disembel
me because my mom gave me tickles.

Speaker 3 (34:47):
And that would definitely save you from the line. But
maybe there is something there, because it does feel like
you're more ticklish in like your neck area and your
belly and behind your knees, like places that you're I
guess are a little bit more vulnerable. That might be
like the genesis of this idea, but yeah, I agree,
it sounds like a post facto explanation.

Speaker 2 (35:06):
Yeah, And how would you even test where you're more vulnerable?
Like what does that like? What does that even mean?
Is it like the density of blood vessels in that area,
the like proximity to organs? I don't know anyway, That's
that's an idea. These things are hard to test. Another
idea is that like rough and tumble play in general

(35:28):
is an important thing for our species and for other
great apes. And making it enjoyable is a way to
ensure that we like kind of keep doing it, and
also having that enjoyable interaction produces social reinforcement that helps
improve our bonds. But I feel like that gets a
little confusing because some people hate being tickled, and so

(35:49):
why do we laugh when we hate it? And is
that really improving our bonds? But I, you know, I
can imagine wanting to make rough and tumble play fun
so that you learn how to do it could be important.

Speaker 3 (36:00):
Well that makes me think of lots of other creatures
that play, you know, wolves for example, and dogs and
cats play. Are they also ticklish? Do you have to
be ticklish in order to enjoy play?

Speaker 2 (36:10):
I don't know if you have to be ticklish to
enjoy play, but scientists think that they've seen something that
looks like tickling and looks like enjoyment of the tickles,
at least in great apes.

Speaker 1 (36:23):
Cats. Rats, rats, Yeah, rats, And so this was so.

Speaker 2 (36:28):
I went to Bowling Green State University for my bachelor's
and my masters, and one of the things that this
university is known for is that in the psychology department,
there was a guy who discovered that rats like to
be tickled and they laugh in the like ultrasonic range.

Speaker 1 (36:44):
And so this was our big claim to fame. Yak
pank step I think.

Speaker 2 (36:50):
And yeah, and so he would like he'd you know,
kind of tickle them, and he'd have this this thing
that would pick up their sounds and then turn it
into a sound that he could hear, and it sounded
like they were laughing, and they would come back for more.

Speaker 1 (37:03):
And so it seems like it was a thing that
they enjoyed.

Speaker 2 (37:05):
And they would sometimes also make this noise with each
other like they were enjoying it when they were like
kind of wrestling and playing.

Speaker 3 (37:11):
So it wasn't just that he knew how to tickle
the rats. They were also tickling each other. Yes, wow,
incredible the rat tickler.

Speaker 2 (37:17):
And one of the papers that I read pointed out
that there's a fair bit of debate in the field
about whether or not this is really tickling or just
like some pleasurable a noise that indicates pleasure and it's
just like sort of enjoyment in the interaction. But great
apes definitely do do tickling. And babies, just like human

(37:37):
kids will like, you know, they'll get tickled by their
mom and to ask for tickles, they'll like put their
arms up in the air and expose their armpits, and
as the moms get close, they'll like kind of pull
them back down in anticipation. So it's very clear that
like they enjoy it, they're asking for it, and it's
like a social thing.

Speaker 3 (37:53):
It's a display of affection for sure. Well, how early
can people get tickled? Like can you tickle a newborn?

Speaker 2 (38:00):
So we don't respond to being tickled until we're about
six months old, and so there's a question now if
you don't do it right when you're born, is laughing
in response to tickling innate? So like something you would
do even if you didn't encounter any humans at all
for a year or something.

Speaker 3 (38:18):
If you're raised by wolves, could you be tickled?

Speaker 1 (38:20):
Yes, that's right, unless wolves tickle and then you know,
but if.

Speaker 3 (38:25):
You were raised by rats, you could be tickled. It
sounds like that's.

Speaker 1 (38:27):
Right, Yeah, absolutely, But I wouldn't recommend that.

Speaker 3 (38:31):
Nobody's getting an IRB for that study.

Speaker 1 (38:33):
No, I don't think so.

Speaker 2 (38:35):
And so the question, yeah, so are you born with
the ability to be ticklish or is it something that
you learn? And so one of the ideas is like
parents when they've got babies, they'll like tickle their baby
and they're laughing and smiling because they're enjoying the interaction,
and so do babies learn, Oh, this is when I'm
supposed to be laughing and smiling.

Speaker 1 (38:54):
And then in the nineteen.

Speaker 2 (38:55):
Forties there was an experiment that I feel like is
maybe a little ethically dubious way. The dad and the
mom both agreed that when they tickled the baby, they
were going to put a mask on their face so
that the baby couldn't see their expression, and they were
going to not laugh. And they would laugh during other
interactions with the baby, but when they tickled the baby,

(39:16):
they would not be laughing, and they were trying to
see will the baby laugh on its own?

Speaker 3 (39:20):
Who is doing these experiments on their children? Oh my gosh,
I know, right.

Speaker 1 (39:23):
And in the nineteenth you know, nineteen forties was a
different time.

Speaker 3 (39:26):
I guess I'm not volunteering my children for weird studies.
Like what if I'm never nice to my children? Well,
they still love me?

Speaker 2 (39:32):
Yeah, Well, but your your kid's poop has been involved
in all kinds of experiments, so I don't And you've
got poop in the freezer I don't know how high
a horse you can sit on their, Daniel, But I
see that in terms of like things you'd talk about
with your psychiatrist. Yeah, probably you know your dad and
your mom not laughing with you when you get tickled
is higher up there.

Speaker 3 (39:52):
All right, So what did we learn by ruining this
baby's life?

Speaker 2 (39:55):
The baby did spontaneously laugh on its own at six
or seven months, So it looks like laughing is innate.
It's just something that we do, whether we are responding
to laughing that our parents are doing or not.

Speaker 5 (40:07):
I see.

Speaker 2 (40:08):
Maybe you could even think of it as like a reflex.
When someone does this to you, you do it back.
But as far as like why we do it, we
don't really know, and it's hard to study.

Speaker 3 (40:19):
Well, I was wondering if the great ape connection was
going to help us loop all the questions together, because
maybe there's a connection between fingerprints and tickling. Maybe you
need fingerprints for better tickling.

Speaker 2 (40:30):
Oh yeah, so you can get like a better grip
on the belly of your baby.

Speaker 3 (40:36):
See, I'm a biologist. I can just come up with
these ridiculous hypotheses.

Speaker 2 (40:40):
Well, then you got to test them, Daniel. That's the
next stage. But it turns out that most of the
research we've done has been on the first kind of tickling.
We talked about the light kind that sort of sounds
a lot like itching, but there's not a lot of
research on this second kind. And part of that is because, like,
you know, some of the ways you might study this

(41:00):
would be like you'd put someone in an fMRI machine
and then look at like what their brain is doing
or something. But when you tickle someone like this, they
move all around, and now it's hard to get data
on them.

Speaker 3 (41:11):
Y'all are missing Kelly's little dance that she does when
she talks about that.

Speaker 2 (41:14):
Yeah, I'm pretty expressive. Should have been Italian. But and
then the other thing is, like, you know, when you're
doing an experiment, you want to make sure you're standardizing
what's experienced by the people in the experiment, And so
how do you standardize tickling? Yeah, like, because everybody responds
in different ways to tickling. Some people like it harder,

(41:37):
some people like it lighter, some people it's you know,
most ticklish on their necks, some people on their knees
or something. And we really don't understand why that variability exists.
And we don't really understand how to measure tickling because
some people will be like he, some will go fall
and like what scale do you put those things on for?
Like how much someone's enjoying this?

Speaker 3 (41:56):
And it's not just a physical response, right, Like you
don't have to touch somebody, as you were saying, like
people anticipation of tickling can trigger the reaction.

Speaker 2 (42:05):
Yeah, right, And there was actually there was a discussion about, well,
could we standardize this by having a machine that tickles people?

Speaker 1 (42:14):
So so they thought that that maybe people.

Speaker 3 (42:19):
Just imagining some sad person out there who has no
friends and nobody's ever tickled them, like ordering a tickling
machine on Amazon instead.

Speaker 2 (42:26):
Well, so that okay, so that might work because this
they did an experiment where they had somebody underneath a
table or it was something like that, and there was
a person on top. And the thing that they were
told is that something like fifty percent of the time
you're going to get tickled by a robot and fifty
percent of the time you're going to get tickled by
a person, and you're not going to know which one's
the person and which one's the robot. And people responded

(42:49):
similarly to both, so even if you think you're not
getting tickled by a person, you think it's a robot,
you respond the same way, but you know it was
actually a person tickling them the whole time, and I
don't know anyway. Yeah, and then you know, like responses
also depend on whether or not you know someone, because
if you don't know someone, then it's kind of creepy
and you feel different about it.

Speaker 1 (43:09):
So it's complicated.

Speaker 3 (43:11):
Yeah, I don't think I want to be tickled by
a robot. No, thank you.

Speaker 1 (43:13):
Yeah, no, I don't.

Speaker 2 (43:15):
I don't feel like i'd be able to get over it.
But I also wouldn't want to be in an experiment
and get tickled by a stranger. There was at least
one paper I read where an experiment was done where
people in a tickling lab were tickling each other, which
seems like a problem to me because they like probably
have some expectation for the outcomes of the experiment, which

(43:38):
might impact the way they respond to the tickling. So
the point is this is hard to study.

Speaker 3 (43:45):
Well, what about zooming in in the biology, is it
really impossible to study like on the microscopic scale, like
what's happening inside your skin and what signals are being sent.

Speaker 2 (43:53):
I don't think it's impossible, but the papers that I
read suggested that we really don't know much. So let
me let me sort of. There's a twenty twenty five
paper written by kill Tenny in Science Advances, and here's
what they say. Gargolesis or tickle is one of the
most trivial yet enigmatic human behaviors. We do not know

(44:16):
how a touch becomes ticklish, or why we respond to
other people's tickles but not our own. Right, no theory
satisfactorily explains why touch on some body areas feels more
ticklish than on others, or why some people are highly
sensitive while others remain unresponsive. Gargoleisis is likely the earliest
trigger for laughter in life, but it's unclear whether we

(44:38):
laugh because we enjoy it. Socrates, Aristotle, Bacon, Galileo, Descartes,
and Darwin theorized about tickling, but after too millennia of
intense philosophical interest, experimentation remains scarce.

Speaker 1 (44:51):
Wow, so that was a review written this year.

Speaker 3 (44:53):
Do you think experimentation is scarce because funding is thin,
because it seems frivolous and unimportant, like it's not a
major medical issue. It's not going to solve any problems.
It's just sort of like a curiosity.

Speaker 1 (45:05):
I suspect that's part of it.

Speaker 2 (45:06):
Yeah, yeah, I mean, if I had a million dollars
to give to cancer or understanding tickling, I might.

Speaker 1 (45:13):
I think basic research is critical.

Speaker 3 (45:15):
What if tickling cures cancer?

Speaker 1 (45:17):
What? Maybe? So?

Speaker 2 (45:21):
I mean I think it's an important question. I hope
we get more funding, but at the moment, we don't
know much about it.

Speaker 3 (45:25):
Yes, all right, all right, well then let's turn our
attention to the other mystery of human reactions, which is
the yawn.

Speaker 1 (45:32):
Yeah.

Speaker 2 (45:32):
All right, So, Daniel, out of vertebrates, how common do
you think yawning is a vertebrates?

Speaker 3 (45:40):
Well, I've definitely seen cats and dogs yawn. I remember
my rats yawning. So we're getting pretty small. I'm guessing maybe, well,
I don't know what I have. Fish can fish yawn?
They're vertebrates. I would guess I'll land vertebrates yawn? Am
I doing?

Speaker 1 (45:55):
You're doing well?

Speaker 2 (45:56):
But I studied fish for my master's in my PhD.
And they definitely yawned. They yawned.

Speaker 1 (46:03):
Yeah, And so.

Speaker 2 (46:06):
Yawning is a stereotypical three phase behavior where first you
like open your jaw really wide, and then you kind
of like contract the muscles. You close your eyes Yep, exactly,
just like just like that, and then your jaw sort
of like passively closes, and we see this behavior throughout

(46:30):
the vertebrates.

Speaker 1 (46:31):
Wow, it's ubiquitous. And so there's two kinds of yawns.

Speaker 2 (46:34):
There's spontaneous yawn which is what we're gonna talk about first,
and then there's contagious yawning. And Dylan wanted to know
a lot about contagious yawning. But let's talk about first
about why we yawn at all.

Speaker 3 (46:46):
Yeah.

Speaker 2 (46:46):
I feel like when I started researching this, I thought
I knew what the answer was going to be, and
it wasn't what I thought. So were you also when
you were a kid told why we yawn? And if so,
do you remember what you were told?

Speaker 3 (46:58):
I I remember some not very credible explanation about getting
more oxygen or something, open your mouth wider to breathe
more deeply or some nonsense.

Speaker 2 (47:09):
Yep, that's what I was told too, And there's apparently
no evidence for that. People have looked and checked and
it doesn't really work. Fetuses yon too, which doesn't necessarily
mean that it doesn't have to do with oxygen, but anyway,
not a lot of support for that. There are some
things that to me seem more like identification of correlations
than explanations. And so we tend to yawn when we

(47:31):
wake up or when we're about to go to bed,
and so there's this idea that yawning has a rhythm
and that yawning is part of quote facilitating state change
and is associated with arousal. And so something about yawning
helps you, and not like arousal in a mommy daddy
sexy way.

Speaker 1 (47:52):
But why did I say it that way? I don't know.

Speaker 3 (47:55):
That's the least sexy way to say that, Not in
a romantic sort of way, but in a what kind
of arousal you're talking about now, like awake yourself up
kind of away.

Speaker 1 (48:08):
Yeah, that's right, that's right. I wish I had done
that differently, but you know, it was funny.

Speaker 6 (48:12):
So I was trying.

Speaker 1 (48:13):
I was thinking what is a kid friendly way to
say it? And think I totally whift all right?

Speaker 3 (48:20):
Message received? The message received? But yawning is part of
waking up because it feels to me more like people
yon when they're sleepy.

Speaker 2 (48:27):
Yeah, so I think the point they're trying to get
at is that it's a state change. So you're going
from one state asleep to another state awake, or you
can do it in reverse, but it's some way in
which your body prepares for transitioning between these two different
phases of our lives, asleep or awake. But again, to me,
that seems more like there's a correlation. Yeah, like where

(48:50):
this happens more when you wake up or when you're
about to go to sleep. But that doesn't help me
understand why you're doing it. And I couldn't find satisfactory
answers for why that facilitates the state change, especially if
it's not like getting more oxygen to different parts of
your body.

Speaker 3 (49:05):
But there's lots of studies about sleep and changes in
the brain as you wake up and fall asleep. Surely
somebody must have identified like neurological mechanism or basis for yawning.

Speaker 1 (49:15):
I don't know that they have.

Speaker 2 (49:17):
And again, so I found another review from this year,
and it's not as long as the last one, I promise,
and it says existing literature has demonstrated that yawning can
be attributed to various factors. However, there's currently no consensus
on the primary cause of yawning, so we don't know.

Speaker 3 (49:33):
But look at big science protecting their central dogma. Huh yeah. Actually,
like this is another great example of like scientists are
happy to admit when we don't know something, and lack
of consensus also means like some people think it's A,
people think it's B. We don't really know yet, so
let's keep arguing about it. Yeah, anyway, just want to
point that out.

Speaker 1 (49:51):
Yep, Nope, totally agree.

Speaker 2 (49:52):
But so there's another class that says that class of
scientists that say yawning is about doing things help you
cool your brain down. And so I think this is
about like the you know, your vessels around your head
get a little bit bigger when you do this, and
that like carries cool air or cool blood.

Speaker 1 (50:12):
To your brain.

Speaker 2 (50:13):
I'm not quite sure I understand the mechanism through which
this happens, but there have been some studies and animals
where they have like cooled the brain region and there's
been less yawning, or they've heated up the brain a
little bit and there's been more yawning. So there does
seem to be some correlation between the temperature of the
brain and how often you yawn. So maybe that is

(50:35):
part of the answer, But then that doesn't explain why
there's a morning and an evening pattern to it, Like
is your brain like really hot right before you go
to bed, and like why would that be?

Speaker 1 (50:47):
I don't I don't know.

Speaker 3 (50:49):
Amazing, amazing, incredible that we've been doing these things for
thousands of years. Its wondering about them for thousands of years,
and still nobody knows the answer. I know some scientists
out there. There are still so many questions for you
to crack.

Speaker 2 (51:01):
Totally crazy, Okay, And so then Dylan's the second part
of Dylan's question is about contagious yawns, right, and we are.

Speaker 1 (51:11):
Equally clueless here.

Speaker 2 (51:12):
So there's some hypotheses that like, Okay, if you look
around and you see that somebody in your troop is yawning,
for example, maybe or like you're in a wolf pack
and one of the wolves is yawning, that could be
information to you that they're not as alert as they
could be, and now you become more alert. But that

(51:32):
doesn't really explain why you would yawn.

Speaker 3 (51:35):
Also, yeah, that would suggest the opposite, Yeah, you would
not yawn when they're yawning.

Speaker 2 (51:40):
Right, or so maybe it's a coordinating behavior thing, like, oh,
it's time for all of us to go to bed,
so I'm gonna yawn so that you know that I'm
about ready to go to bed, and that'll coordinate our behavior.
But that also doesn't seem necessary because like, just lay
down and shut your eyes.

Speaker 1 (51:53):
Everyone's gonna be like, oh, Kelly's asleep. I guess we're
going to bed.

Speaker 2 (51:57):
So I don't necessarily feel like you need it for
synchronizing group activity or that it needs to be associated
with group vigilance.

Speaker 1 (52:03):
But those are some hypotheses.

Speaker 2 (52:05):
But what's interesting is that yawning can be contagious across species.

Speaker 1 (52:10):
Two.

Speaker 2 (52:11):
So like if you see a gorilla at the zoo yawn,
you might be more likely to yawn too. And if
you just hear about someone yawning, you might start yawning.

Speaker 3 (52:21):
Or if you listen to a twenty minute podcast discussion
of yawning, you're going to be yawning.

Speaker 2 (52:25):
I have yawned a couple times during this conversation. So
I looked at a study where they had humans watch
videos of non human animals yawning.

Speaker 1 (52:34):
Oh yeah, cute.

Speaker 2 (52:35):
I want to be in that kind of study, But
it did look like humans were yawning in response to
like cats yawning, which makes it hard to understand like
why that benefits anyone. Yeah, and so there's a lot
we don't understand about yawning.

Speaker 3 (52:55):
Also, I think it's awesome that biologists try to think
of these explanations. But I wonder if sometimes the answer
is just like, well, your brain works in this way
for some completely separate reason, and this is a byproduct
of it, and it's not harmful, and it just went
along for the ride evolutionarily, and it maybe is a
way to figure out some other thing that's happening in

(53:16):
your brain, but there's not necessarily some independent reason for
it to exist. Do you think that's possible.

Speaker 2 (53:21):
Yeah, I think that's a fantastic point that applies both
to yawning and to tickling. It could be a byproduct
of something else. It doesn't really help us, but there's
you know, it also doesn't cost us much, so there's
no reason for evolution to like cut it out of
our behavioral repertoire. And so yeah, at the moment, both
of these behaviors are just like big question.

Speaker 3 (53:42):
Marks, fascinating wonderful. I love these question marks and science.

Speaker 2 (53:46):
Yeah, and I guess I had assumed that we knew
more about tickling and yawning. So thank you very much
to Dylan and Jude for teaching me more about what
we don't know.

Speaker 3 (53:56):
Let's hear these answers tickled them or made them yawn?

Speaker 8 (54:00):
Hi, Daniel and Kelly, thank you for the great response.
I think it was fascinating, and also I don't think
it's at all frivolous. It's bothered and tantalized minds for
literally millennia. They need more funding for all kinds of
scientific research, including tickling. Thanks for all you do, and
thanks for all the research.

Speaker 5 (54:19):
Thank you for tackling this question. It definitely tickled my
curiosities to hear that even fish on and I like
the idea that these are simply behaviors that evolution had
no reason to get rid of, so it didn't. As always,
I look forward to hearing what more you have to
say about this extraordinary universe.

Speaker 2 (54:37):
All right, thank you so much. We love getting listener questions.
Please send us your questions through the discord channel. You
can send them to us by email at questions at
Daniel and Kelly dot org. You can also send them
to us through social media, though I'm slightly less likely
to see them if they come through Instagram or something
because I'm technologically deficient. But if you said to us

(55:00):
as an email or through discord, we will see it.

Speaker 3 (55:02):
And even if you don't write to us with your questions,
keep asking them, keep being curious about the universe.

Speaker 2 (55:08):
Yes, all questions get an answer. Some questions end up
on the show.

Speaker 3 (55:12):
Thanks very much everyone.

Speaker 1 (55:14):
Thanks.

Speaker 2 (55:21):
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