You're listening to Weird and Dead, the paleontology podcast
that tells evolution's most embarrassing and bizarre
stories. I'm Megan Wetherell.
And I'm Amy Atwater, and we're two living scientists who are
weirdly excited about dead things.
In this episode, I surprised Megan with a full hour of
scrotum conversation, and Megan displays a level of expertise in
the topic that worries even herself.
What is a scrotum, what groups have them, and why do testes
take a multi week odyssey to occupy such a humiliatingly weak
external position? We talk varying theories
including heat control, motion of the ocean, and of course,
training sperm for their eventual obstacle course and
inhospitable destination. Like always, read the content
warnings before continuing, especially if you don't like
scrotum jokes or if you are sensitive to the idea of balls
falling off, balls punching through things and causing
hernias, etcetera etcetera. OK, I'm going to open up this
scrote pics. Yeah.
OK. What are we talking about today,
Amy? Let me open up my scrote notes
to get into. Amazing.
To get into this layered discussion we can have about the
evolution of the scrotum. That's really what you have to
take. No wonder you were like, oh,
this might take a Really. Long time.
It didn't start with that. That's where I ended.
I was going, oh, AB you low key just deep dove into that
epidemis into yeah, excellent. I'll tell you how it started,
though, and this is hilarious as well.
Is your stuff working? Yeah, just double checking.
I heard a scary sound. Giving birth.
Nope, nobody's giving birth. They're all doing this
suspicious. Like they do like the band photo
thing where they kind of walk off away from one another and
they're like emo, but they haven't started actually giving
birth yet. So they're they're leading up to
it, but. Oh, I'm so glad I'm not them.
And instead you're stuck with me talking about some of the
equation that goes into making those babies.
So at the end of January, I was invited to go to Dino Fest at
the University of Utah Natural History Museum of Utah.
Yeah, it was. Anyway, I said it better in the
promos. Don't worry, I was invited
mostly to do social media stuff and like, talk to the
researchers that they invited, which was a little weird being a
researcher myself. And I was like, whatever.
They paid me to go to Salt Lake City, one of my favorite cities
in the entire world, and yeah, it was soup.
It was great. I loved it, had a great time.
Anyway, one of the researchers I met because this year's theme
was Prehistoric Skies, and it wasn't just dinosaurs.
My mind is just reeling trying to figure out how prehistoric
skies as a theme goes through scrotums, but I'll be patient.
Megan, yeah, it's me. It's me.
So I got. There, OK.
And. So we had folks talking about
early pterosaurs and all that. Jingmei O'Connor was there doing
a keynote one of the days on the Chicago Archaeopteryx.
I interviewed her briefly for this, the Utah thing, and I
immediately went to crop milk. I was like, so come on, you're
the bird expert crop milk. She was like, who are you?
So that's how we get to these places.
And then I met Doctor Matt Jones, who I had not met before
and a very nice human. He actually is a professor at
Arizona State University. So I.
Mean but don't OK. I don't know what.
So he studies bats and he was invited to.
Do a talk on. Bats.
Yes. And he shared an office in
Graduate School with who is now Doctor Rust on that paper that
we are you. Yeah.
So when I dropped IGMU, he was like, no way.
And I was like, what? You know, IGMU And he was like,
yeah. And then I started saying land
mammal ages to him. And he was like, yeah.
And I was like, this never happens.
This is awesome. Yeah.
We very much enjoyed having other mammal people to talk to.
And after after we were comfortable, I, of course was
like, what's up with bats and their Dick bones, man?
And he was like, yeah, I mean, it's interesting, huh?
Like, so super specialized and they still have that.
And he's like, but you know, Scrotifera and I was like, what
Scroto What? It's like Scrotifera, that
taxonomic group that is used to define mammals.
Yes, it's pretty recent because it's done based on the genetic
stuff. But you know, once we realized,
OK, back it up, it's like we had our old trees of life, our old
evolutionary relationships based on just like morphology and
fossils and modern day creatures.
And then modern genetics came along and was like, that's
wrong, that's wrong, you're wrong.
Nope, totally distantly related. And actually those ones are
super closely related and they don't look alike at all.
And so genetics has helped us understand groups like
Aphratheria, which includes things like hyraxes that we just
talked about and elephants and just some like animals that
don't look anything like each other.
Hyraxes look like rodents. And anyway that manatees.
And it's thanks to genetics that we've been able to understand
that these different groups or classifications exist.
And one of the groups that is used today is Scrotifera.
And it is, Yeah, it is a subgroup to let me find my.
I should have put that one first, but I it ruins the
guessing game. So I'm going to still make you
play the guessing game before I explain all.
But it's like if you have Laurasia theatres, Right.
So Laurasia theatres are insectivores, bats, carnivores,
Penguins, ungulates and whales. Yeah.
Yes. And then it splits off with the
insectivores or the euliptotypha phylia, whatever those guys.
Yeah, those guys, yeah. Eulipotyphla are true
insectivores, including hedgehogs, moles, true shrews,
and a few other weirdos. A little insectivore things,
hedgehogs, and then their sister group is Scrotifera.
And that includes a bunch of, as you know, because you just have
them in your brain, a lot of those animals, which is funny.
Because people hold up. No, let's back up.
Scratch, scratch that from the record.
No. You know what a Laurasia theory
there is where none of our listeners have any frame of some
some of our. Scrotums.
OK, that's not I know. What a Laurasia dude.
You sent me a picture of a scrotum on the ground of your
farm like a month ago. Actually, I was at this
conference sent me the fuzziest, wooliest scrote pic.
You started this, so don't you even.
You've handled way more scrotums than me.
Way more. You're right.
I'm sorry. I take it back.
You got me pinned.
You got me pinned right away. See, and that's like it.
Ever since I've talked to Matt, I've just had scrotifera on the
brain. So I started just trying to find
information on scrotifera. But because it's really just
like a relatively recent term taxonomically used, it's not
really used in the literature. Like it's not really talked
about even doing a deep dive Google Scholar, like really just
different references to it being designated based on genetics to
contain these different groups. So I've got more curious than
about just scrotums in general. If it earned a name to an entire
clade of animals. But some of the animals outside
of Scrotifera have scrotums. I mean, we are not Laurasia
theories and male humans tend to have scrotums.
I've been, I've been told. I've never seen a fair yourself.
Gave birth to a baby boy? Have no idea.
There's always sheets involved. Sheets and we are Uarkonta,
which is a sister group 2 Laurasiotheres.
Uarkontaglieres includes primates, tree shrews, kalugos,
rodents and lagomorphs which are rabbits and picas.
And most Uarkontaglieres have scrotums.
And then there's even some I did not know that the name for
Afrotheres and xenarthrans is Atlanta Janata.
So nice to say Atlanta Janata. Afrotheres include golden moles,
aardvarks, elephants, sea cows, hyraxes, tenrax, and other
shrews that are not true shrews. Zen arthrans are sloths,
anteaters, and armadillos. I mean, I'd rather say that than
Scrotifera. Sure, I guess they it rolls off
the tongue. So that is how I end it rolls
off the no comment. Oh God.
So that's how I ended up Googling.
Does this animal have a scrotum? Does this animal have a scrotum?
How about this one? Does this one have a scrotum?
Oh, oh, wow. So there was a lot of that.
And it kind of has now unravelled into the evolution of
the scrotum because it is a bit of an evolutionary mystery in
some ways if you think about it. So, I mean, I'd love to hear
your thoughts just right off the bat of the quandary of the
scrotum. I mean, First off, not shocked
that biologists haven't picked up the use of the name
Scrotifera. Shocking that they don't want to
call animals that. Yeah.
I feel like anytime you get into those sorts of bigger
phylogenetic clades, my brain kind of just shuts down and my
eyes glaze over because I'm like, well, yeah, great.
OK, We're Loracia theers. That is just another fancy word
for a bigger grouping, which at a certain point those words get
so long and ridiculous it would just be.
Easier. What are you trying to just not
to say? Yeah.
Would not just be easier to say, you know, like, you know,
Cyrenians and elephants or whatever, Like that's.
I mean, that's not yeah, just, you know, sometimes I think we.
Could just call them weirdos, which is what would be accurate
for that group anyway. What the fuck?
Like WTF? Their whole group could just be
WTF. Is anyone listening?
So that's that's that's my only thoughts thus far.
No thoughts on scrotums except that you know not all mammals
have them, and I guess I hadn't really thought about that being
a unifying characteristic. I read an article that literally
started the first line was while the possession of a scrotum by
most male mammals is considered a hallmark for of mammalian
evolution and I was like. I'm.
Sorry, hold the fuck up to all of the three Dicks on this
paper. I cannot tell because you are
all very European and Eastern European.
I don't know. I shouldn't say that either.
That's just not a hallmark that I think of.
Me neither, I think of them as I mean, I'm pretty sure Dan Savage
on the Savage Love cast is the one who said that we shouldn't
be calling people pussies, right?
Pussies are strong. They can take a beating and push
a baby out, which is his quote. But I've used it many times and
it's like call, call him something that's actually weak,
like a scrotum, because they're these sad little dangly very
exposed, which you would think when holding on to something
that is necessary for the survival of your species, you
wouldn't. Like take like a shell.
It's like when they dangle the dead chickens over the
crocodiles to make them, like, jump up and try to like, why are
you? Yeah, exactly.
Why are you taunting us? Scrotum I'm assuming applies to
the external like sack right? Like a hippo has balls but it
does not have scrotums. And I know this because that one
time for the blog I had to read the paper about how if you want
to. Get to hippos.
Castrate a hippo. You have to.
They had to do like a whole bunch of like replicatable
surgeries where to tell you which angle to hold the hippo
leg at because they don't have internal balls.
So they can kind of just wiggly wobbly around like just get lost
I guess in there. So if you want to have a real
fast in and out castration, but they.
Don't hold. The leg in the exact right spot.
Well that's my thought is I guess they would not have a
scrotum, right? They don't have the balls and
we're yes. And so you, Oh yeah, you can
have internal testes. That's called.
There's a term for it that also made me laugh.
It is called Testicondyle. What?
Testicondyle. No testicondi.
That's it. By the way, long time listener
BFF of ours Carrie Weber thought of her the whole time I
researched this. I know I'm saying this wrong.
I look forward to you correcting me in a few weeks.
But yes, testicondi, it's testicondi is what it means if
they are internal testes versus going there descent, which is
called the something hilarious as well.
Descentus tester Caloria. Nope, that's still wrong.
Yeah, yeah. Testicularum.
Descentis. Testicularum.
Yeah, there we go. There's a lot of fancy words
used here for when your balls drop.
That's what that means. But essentially, yes, the
scrotum itself only exists because of the testicles.
It is there only to be the SAC that contains the balls.
And this is something the whole balls drop.
Like, have your balls dropped? Your balls usually drop well
before you're born if everything goes as evolution intended,
which, by the way, evolutions drunk.
So we don't really know how that's going to go.
OK, Yeah. But essentially at 8 weeks of
development, the human fetus has structures that either become
testicles or ovaries for females, For those of us who
have ovaries, they stay, they move a little bit, they have
their own journey. We have also some soft tissue
stuff. Round ligament is the term I'm
thinking of that can cause some issues for us.
But for boys or for people with testicles, they it's a seven
week voyage from the abdomen. They, they form near the kidneys
and it's quite literally like a marionette like pulley system of
these different muscles and ligaments that are like forcing
them into the sack. And one of those ligaments are
the one that kind of marks the path or sometimes called the
rudder of it is the gubernaculum.
Did you ever have to learn that one in high school?
I missed it on a high school IB biology test.
I've never forgiven myself. Anyway, I think it's hilarious.
It's called the gubernaculum. It's your Dick.
It's winter. Balls.
OK, OK, I. Don't know.
I always thought it was really funny.
OK. So sometimes the testicles stay
up by the kidneys and they don't go anywhere at all sometimes?
They work that you're doing right now with your hands is
really making this whole thing so much.
Better Internet works better again.
One day we'll try. We'll try one day videos.
So actually, you know, I think I've got a decent way to depict
this. I'm going to change up.
Don't go to the images. I'm going to change the one.
Actually, no, you can just go ahead and scroll.
Sorry, OK. But go ahead.
Just Oh no. Sorry, it's just a cross section
of a male reproductive system. OK, Yep.
Oh, I'm at the doctor's office. OK.
Do I need to keep going or am I staying in the doctor's?
Office. So that second one, the black
and white picture is the old. Document.
Do this. Yeah, that is showing you
essentially your desensus testicularum.
That is this journey that I'm talking about.
So where the testes start up by the kidneys, then they drop down
thanks to the gubernaculum and the caudal genital ligament.
And those are what's essentially pulling it down.
And you'll see in the upper right quadrant, it's chilling in
the abdominal cavity. Sometimes that's where it stops,
right? So if they do half the journey,
they make it here. It's closer to the genitals, but
it is not external. It is still in the abdominal
cavity. Then the fucking crazy shit
about the true nut sack is that it busts the fuck through your
abdominal wall, through these inguinal canals and yeah, it and
it takes layers of muscles and abdominal lining with it.
It just goes bloop, like a little lava lamp bloop into your
scrotum and that and that. It gets worse, It gets worse, it
gets worse. That little jump that it takes
that the gubernaculum is setting the track for is why people with
testicles get hernias so much. That's a weakness.
It's a forever weakness in your abdominal wall because you
fucking sucker punched your nuts through it.
And now there's always like a slightly weaker point there.
And that's why I don't know if you've had this experience.
We have multiple friends who have stories of being little
boys and like trying to pick up their family dogs when they were
little and like getting hernias. We have multiple friends with
this story. They like if you pick up
something too heavy and especially if you're still
Pretty Little, sometimes part of your intestines will just back
through this weakness in the abdom.
Like really it's in an unpleasant place if it happens.
And that is because of this early descent of your testicles
while you were in your Mama. And now that's why men get
hernias. Women can still get hernias too.
Like I was saying, ovaries go on a slightly similar journey and
we have some similar tendons and what not.
So ours is the round ligament. And so that is a weakness too.
And it is where women, if you get a hernia, are likely to get
one. Not nearly as common as it is
with men, partly because of this, this pilgrimage that
they're going on to get to the SAC.
Is there a correlation between size of the testes and
likelihood of hernia? Oh, that's a great.
Who's got big balls and an intestinal hernia?
Yes, right into the balls. How much do they?
Because as I also read sometime there's there's the occasional
scrotum apparently with some mammals like it only comes out
during mating season. So, yeah, So how much scrotum?
Yes, I got a goodbye. See, little scrotum, it's pretty
cold. And then it makes its way home
so that if it's in that scrotal sack, that's kind of this
furthest stage of journey that it can take.
And if you Scroll down, you can see this demonstrated these
three different takes in three different mammalian species.
Would you like to describe what you see?
So the artist from My Little Pony.
A. Beautiful line drawing of are
the. Perfect kidneys.
Kidneys. Of the kidney to testicle ratio
and relation. And seriously, that fucking
horse. My Little Pony Feet 1000%.
Yeah, it's Lisa Frank realness. Yeah, you could put a Unicorn
horn on there and I'd believe it for sure.
Also love that they're both as big as the elephant, the seal,
and the horse. Yeah, well, they really wanted
you to see how big those nuts are.
So we are seeing the three different conditions here.
So an elephant or an Afrothere which is going to represent
Afrotheres here does not have any part of it.
It's it's testes have stayed near the kidneys where they
first developed. Zero journey, not move, zero
journey. They were like fuck that, not
going to do that. This is a seal and the second
photo and a seal has made again the first part of our journey
that we talked about, but has not gone as so far to pop on out
that abdominal, the wall and go into a true scrotum.
So it is still located in the groin region and it's just like
above the skin? Kind of, yeah.
Meanwhile, the marks. Out.
Because they wanted the leg to demurely cover the testicles and
I guess couldn't figure out how to get the leg.
It looks like the testes decided into the thigh like.
I know, I know of like just have it not have that leg That's OK.
Or have it like sticking his leg super far back.
Or I don't know, kicking. Kicking to show the balls.
But. Right.
So then the question, of course there are controversies right in
everything that we start to dig into, but the question ends up
going so mammals, some of them have them, some of them don't.
What's the deal? Did all ancestral?
Did the ancestral did the first ever mammal slap that sack
around like, or has it been, was it at did all placental mammals
start with this? Did all Mediterraneans like we
just aren't quite sure. And then the question is also so
with the times that it has been, has it been lost or has it, was
it never there? Right.
These sorts of questions on timing that we're not quite
sure. So if we for me makes kind of
sense to just go through that evolutionary tree of mammals and
chat about. Yeah, just who has, you know,
external testicles? They're gonna fix so monotremes.
Monotremes. Oh would.
Your guests be for a platypus nut sack.
Oh God. I mean echidna.
I'm just thinking of the echidna demon hand penis, and I'm really
hoping that they're not adding testicles to that and that that
at least they have some like sense of restraint and that they
have them on the inside. But I'm guessing they have
monstrous, terrible testicles. That would be my guess.
No, they do not have a scrotum. No, my God.
Restraint. Yes, restraint.
Thank you. Which also tells us that it's
unlikely that the the ancestor of all living mammals today had
a scrotum. It's unlikely considering they
are the oldest and the most basal mammals today.
The mom dreams. So no.
And they've now done gene studies and seen that.
Seen that the platypus, instead of having a duplicate gene in a
certain place, it's just a single gene.
And it's that later that gene being duplicated in subsequent
mammals allowed one to go towards testicular descent and
the other towards nipple development, interestingly
enough. So they did not start the party
and they don't have nipples, right?
So it was they were so early to the mammal party that they
missed out. Their gene then mutated in a way
that led to nut sacks and nipples.
And they, they, they themselves have never, have never enjoyed
such such treats. Such a sad life, the monotrem.
So we now, yeah, we know that monotremes.
No ball sack. Wonderful.
So then our next group of mammals is gonna be our
marsupials, our pouched mammals. So what do you think?
Do you think a kangaroo has? I have seen kangaroo ball
pictures. I remember them being on the
wrong side of the penis. Yeah.
Why is it is? It because they're upside down
it. Doesn't come up, huh?
I need. Scrotum trivia.
Okay. Okay, so go ahead and scroll
because now you have to see they're upside down because
they're in Australia. They're also very pendulous,
they've got quite the swing to them and they are essentially
each in their true own sack, like it's a bifurcated sack like
these. Everything about them is
bifurcated. Huh.
Yes, yes, yes, yeah. So they they hang pretty low and
they are in front of the penis. That is correct.
Do they really like? I don't, I don't know.
I'm not a I'm not a cake guru. Amy, you didn't look up if the
low hanging balls that are in front of the penis ever block?
Come on. I don't know.
You're right, You're right. Bonus episode.
Oh, I forgot what I was gonna. I thought I forgot what I was
gonna. Talking about this, Oh my God,
those do dangle. Jesus Christ.
They dangle, yeah, quite a bit. And then, yeah.
And it looks like it is a pouch, which is funny.
It's just their, it's just their junk.
But I think they can retract it in a bit.
So I think that there is some control about that dangle not
getting in the way, but I don't know.
I wasn't there. You went to Australia and this
wasn't something you investigated?
You know, I probably probably did, probably did.
Oh man, I was going to say something and I forgot it, so
that's OK. I'll see if it comes back.
Also, I should probably forget some of the things we're talking
about because this. Is disgusting.
Yeah, you won't. This is going to take place with
some really important information in your brain, but
such is life. I think you were talking about
bifurcated pouches. Oh, I think that was Yeah, I
think that's all that I was going to say.
I was going to say something. I read this really interesting
piece by a guy named Liam Drew, really hilarious piece that was
called The Scrotum is Nuts, which is absolutely quite
beautifully done there poetry. Well, what's interesting about
it is it does seem to mean that the scrotum is evolving
independently here on the kangaroo lineage and their point
of well it's different because it's run of the Dick.
And I was. Yeah, I mean.
I mean, it's your. Testicles a common.
Going on a journey to stab out of your body, like sometimes I
feel like it's stabbing in a slightly different direction is
not that far of a stress. Right, Because it is kind of
this question if marsupials have a scrotum and a lot of mammals
do, but not some of the most primitive mammals in some ways,
if we're talking about zenarthrans and afrotheres.
So is it that that common ancestor had a scrotum and
Afrotheres lost it, or is it that they didn't have one from
their monitoring relative and marsupials gained it
independently and then Laurasia theories gained it
independently. Like that's kind of part of
that, or should I say Scrotifera gained it independently.
So these are the questions. These are still the questions
that haunt my mind. So once we get into our
mammalian group, we've already talked about this after
theories. You saw that beautiful drawing
of an elephant, No movement in their testes.
And then with Xenarthra, they are no scrotum.
So these are our sloths, anteaters.
But I think most of them are in position too.
They make the first part of the journey.
They're just just what lies beneath.
I mean right there, they just don't live long enough because
sloths are so slow. You know?
Maybe if they live like another 100 years, eventually those
slowly descending balls would become a sack.
Yes. Yeah, yeah.
And then they really should say that it's the scrotums are in
Boreoetheria, which is the group that contains us.
You are Conte glaries and Laurasia theories.
You are Conte glories. This is stuff that I get geeked
on. So these are US primates, Tree
shoes, Kalugos. Yes, they all have scrotums,
squirrels, rabbits. Yes.
And some of these, again, are quite dynamic in some ways, like
squirrel testes. Size changes dramatically during
the year based on what? Mating season.
And then rabbits had kind of like they're nuts, could be kind
of weird too, like on either side in their own kind of sack.
So again, if we're saying that having a Dick just in front
means it's a different trajectory, I'm going, I think
there's quite a bit of plasticity in where it swings
just based on who's got it. Wait, hold on back up.
So animals that have a bifurcated sack, does that mean
that they're getting punched through on two sides like
they've got 2 balls? Or is it something that
bifurcates afterwards? Can you have one ball?
Not great. Question.
Oh, Ouch. Probably, probably.
But does that ball, does the other ball exist?
I think would be. Schrodinger's Ball.
Schrodinger's ball. OK but no I think they make this
journey together. I would hope that you only have
to get pushed through that inguinal canal once, but no.
I mean, do they go at the same time or do they go one first?
Is their twin one born 3 minutes before the anyway?
I don't know. I don't know.
See, I told you this is just to whet the appetite.
So we can't make lurasiatheres all scrote bearing and and
therefore scrotifera because of the stupid insectivores.
So these are our shrews and hedgehogs.
They don't have a true scrotum. And I couldn't quite tell from
my reading and looking at grainy photos if it's by the kidneys or
by the junk, but not out of the body for those.
And then what's interesting is, OK, so now we've determined that
there's already quite a few mammals that have scrotum, not
in scrotum, not in it at all. Yeah, now we're in scrotifera.
And OK, so some of the animal groups that we have left, let's
see what's the next one for you to guess.
Do you think that bats have a scrotum?
Again, This is why this should be a category at trivia.
I know that they do, in fact have grotoms.
And that is why if you see pictures of bats and you're not
horrified, that's a girl. Because bats have really wild,
like, external genitalia, it seems like it should slow them
down, right? Yep.
That's not its head.
It's just a set of balls approximately the same size.
Awesome. But what I read is that they're
very good at having them like very close to the body.
Like there's none of the pendulous swing that we see with
these other keeping them close. They keep it tucked, yes, as
much as possible. So yes, bats have bats have
them. Most ardeodactyls have them.
Ardeodactyls are even toed ungulates like cows, deer,
bison, pigs, giraffes, sheep, goats, and many, many more as
well as whales and dolphins. You definitely.
We know more about that than I do.
I do now. The ones that go to the ocean
don't. So whales and dolphins, they
mostly thought to be for streamline reasons, have tucked
this the junk and everything is internal.
We're going to talk also about the theories as to why or the
hypothesis as to why mammals do this, because it's actually not
as simple as I thought it was. So, yeah.
OK. And then presidactyls man, get
kind of weird since we've just determined have a scrotum thanks
to that. Beautiful drawing.
Yep, gorgeous. Rhinos and rhinos and tapirs do
not. No, no ball sacks on rhinos and
tapirs. I don't know.
We were so distracted, always looking at the prehensile Dick
of a tapir. We never noticed that there's no
balls. Well, again, you know, they're
not picking up their leg to display their balls absence so
but that third leg is pretty obvious.
So yeah. OK, so perisodactyls, some have
balls, some don't. Well, I mean they all have
balls, but some have external balls, some don't.
Interesting. I can't Missy now I'm now I'm
reading it again. I'm like, do they have a do they
have a scrotum? I don't think they do, but
anyway I may have gotten I know rhinos do not, so it makes me
wonder about my broader fears. Did you guys have a scrot or no
scroter? Note.
Scroter note scrotum. I'm doing a new Instagram quiz.
Scroter OK, And then we get into our last group, ferre, which is
pangolins and carnivorans, and pangolins do not.
So again we have another scrotifera without a scrotum,
fucking imposters. And then almost all carnivores.
Carnivorans do, but it gets weird again when you go to the
water. Pinnipeds get a little bit
weird. Oh OK, how do pinnipeds get a
little? Weird.
Did you know that one of the many ways you you can tell the
difference between a seal and a sea lion is the scrotum?
Weirdly they don't mention that at outdoor School, they just
talk about external ears. Ears and whiskers and shit.
Why don't we just go to the good stuff?
Did they really have external balls?
What the fuck? So sea lions have external
balls, but from this post I read, I don't think they are
always out if they only develop a scrotum during the breeding
season because it's not that this because they're so
dynamically, you know, adapted for their water environment that
it doesn't make sense to have accoutrements dangling around.
And so they apparently go go gadget scrotum during the mating
season. And I'm like, well, where does
it go? What is it?
I didn't think matter could be created or destroyed Wrinkles.
Get flab. I don't know, but there's a
picture for you. And if you Scroll down, there's
a picture of a sea lion scrotum for you.
Yeah. It's.
Probably taken in Oregon. It's a fucking weirdo at Moe's.
It's like snapping, laying in the sunshine, balls out.
Balls out. You should live in the dream.
Live in the dream, so. And there's our tree that I've
kind of been going down. I should have had that at the
beginning. That's got the Skrotifera on
there for ya. Yeah, that's my last, my last
image of these. Incredible, incredible
adaptations that. But again, if we go back to it
seems pretty weird to have something that is so important
to the survival of your genetics to be in a precarious, rather
exposed area. It sounds like people have done
some fucking weird experiments trying to understand some of the
different factors. But why, Megan?
Why do mammals have a scrotum? So I mean, the explanation I've
always is because that allows them to temperature regulate,
which is why if you do what I did to that cow and you
accidentally castrate only the external SAC.
So he ended up his testes slipped back up into his body
and he still wasn't fertile because his balls could never
cool down. Yeah, right.
Crypt orchid bowl is the term. Yeah, and I mean, I will point
out that Minnie, a drag queen, is an expert in tucking their
balls. There are cavities, gentlemen.
I don't want to hear it. You can shove them in there.
You can put it away OK. You can.
I know it's harder on a hot summer day, but you still right.
So we were all taught that it's the cooling hypothesis that it
is to cool the testes to keep that sperm nice and chilled
before it it's big delivery. Now some folks have said it's
not really the testes that we're trying to keep cool, it's the
epididymides, the individual epididymis channels of that
transport the sperm 'cause they're not fully ready to go
when they leave the teste. That's still part of again, this
like fucking Homer, like Iliad journey that they take, I guess
just. Like shooting it through some
sort of cold shoot, that's that's what they got to do.
So they really got it cool and I'm like, OK, we are splitting
ball hairs here like it's they, the epididymis and the testes
pretty much go together. You can't have one without the
other. If one needs to be cool, you're
probably going to keep both cool.
Now the huge problem with this is that we've already outlined
tons of mammals today that have internal testes and obviously we
are not cooking, they're swimmers because they are
procreating and all of their junk.
Both of these, the testes, the epididymides are totally fine.
So some folks have said, I have hypothesized that it's not that
the sperm needed to be cooled. It was once they were there they
adapted to slightly cooler temperatures, which would still
explain why your bowls junk didn't work because it we are
now adapted to have it be at a couple.
It's a couple degrees cooler is optimal for sperm production in
most mammals than body temperature.
So it's kind of this question of maybe that adaptation was just
because they got shoved out in the cold and they had to adapt.
Now some have also said that they need to.
This is in scientific papers, but keeping sperm cool may allow
the warmth of a vagina to act as an extra activating signal.
Are these researchers shoving their balls into vaginas?
Is that? Why do you need to be?
Why? Why is?
Right by the time the sperm is there next.
To legs all of the time, like why you need right a woman's
warmth from the front. And also, like, by the time your
sperm is in the woman, it's done.
Isn't it usually over for you? Isn't that like, I don't know.
I don't know. I wasn't there.
OK. So, I mean, this seems to be
where the bulk of the research is.
There's some truth to this, as it is adapted for this.
There's also a training hypothesis that was ridiculous,
but it literally is that the scrotum serves to expose the
sperm to a hostile environment in order to train it for further
goals, namely fertilization 'cause my our pussy gonna beat
you up, bitch, so you gotta, we gotta toughen you up.
Like cue, like rocky style, like cut screens of training your
sperm training. Bah Bah, Bah, Bah.
Yeah, exactly. Like running up and down.
Yeah. That it's that they.
Yeah, that they. Are that's stupid as hell.
It is very, it's very stupid and it's not very well supported
because it really doesn't grasp like the there.
Yeah, it's not very well supported, but I had to include
it because it was so stupid and funny.
Now of course there's the display hypothesis, which I
didn't include this, but you know our number one blog post,
right? Was it about balls?
Monkey blue balls. Oh, that's right, monkey blue
balls. I forgot about that.
Yeah, that like summarizes the display hypothesis pretty well.
I forgot. Yeah, we've read A blog together
for two or three years at our most, talking about all sorts of
things, including, like, amazing science and like, feminism.
The top blog post of all time was Monkey Blue Balls because
people look up blue balls and Google is like taju mean this
monkey because sure is shit blue balls for people.
The vervet monkey has yes, the vervet monkey at least
seasonally can have very blue balls.
And I think most of those pictures like the link died at
this point. But the funniest part was that
they were all like looking at their balls with like such
surprise. They're all like.
What are these blue? Yeah, and that part is.
But yeah, some some monkeys, some old world monkeys do this,
some other species display it. Now most folks don't think it
evolved for that to be display. It was probably Co opted is the
thought. And now there's the evolutionary
biology handicap principle, which is that this idea that if
a male, there are two males fighting and one has an arm tied
but tied behind his back and still wins, the female is going
to be like, wow, you're so strong.
And they're essentially saying that if your balls are like so
worthless and like such a burden and you're still able to like
get, get around and be top male, like to be alpha.
It's like, look, look, I can deal with this annoying shit all
the time, you should fuck me. Look at my protuberance.
Isn't this difficult to live with?
Yeah, it's this Peacock. Like if you can, if you can
survive with stupid feathers of a of a Peacock and you can still
survive with that giant announcement to all predators
that you are worthless, slow and have this giant radar on you,
then you must be this alpha male.
And so it's that same idea that right, if you are burdened so
much by your ball, you're superior.
Yeah. So the hypothesis that has the
most support it sounds so stupid but like.
So stupid. That's so dumb.
This is the galloping hypothesis.
Would you like to guess what it entails?
What I mean, it sounds like it entails running, but how do
balls assist with running? Does it shake up the sperm?
Is that better? Like a milkshake.
You want to scroll back actually to the picture of the the cross
section of the male genitalia, because that's how this.
Started. The galloping hypothesis has to
do with pressure in this region, in all of these tubes, if you
will. So if you see the stuff that's
eventually leaving the testicles here, your epididymis and your
vas difference, you know what gets snip snipped all connects
through your prostate before getting shot out the urethra,
right? Those are all kind of in some
ways connected, right? There are no sphincters between
any of those features. And I apparently someone did
research on a rowing team and the intense rowing activity led
to prostate stuff. I guess what being found in
sperm, like it mixed it all up because there are no sphincters
and all of that pressure and weight and change and
positioning in the body kind of caused all of the things in that
system to all get fluent like flushed around together and by
yeah, I guess that's bad. So you create this scrotum.
If you have this all going on internally, there could be a lot
of pressure build up that could cause bad things or kill sperm.
And so it it helps alleviate this weird pressure difference
by kicking the scrotum out of the abdominal cavity.
And they want you to know that a lot of they looked at a lot of
animals that jump a lot like the horse versus the rhino is one of
their points is that a rhino is not galloping and leaping
around, so its testes can stay inside and not have a pressure
difference caused by its locomotion.
Whereas the horse is a bucking in a kicking and needed
therefore to have its balls out of that equation for internal
pressure exchange, if you will. So it basically just like it
makes it so that when you're doing like muscular contractions
in that area, it's not automatically also contracting
on the scrotum and you're less likely to have whatever we're
calling prostate goo go back up into the scrotum.
Is it urine? Is that?
What we're calling their urine contained fluid from their
prostate. So the the the ball sack
actually had nothing to do with that one.
But it's how the guy got to thinking the all the junk is
kind of connected for males and that this there is fluid from
their prostate in their urine because it was just a
pressurized shit show in there from their extreme exercising.
And that that this is yes, that it is necessary when they start,
that mammals needed to move in ways that sharply increased
abdominal pressure. I mean, Kangaroos, that tracks,
huh? Yep, Exactly.
Yep. Yep, Yep.
Bats. Yep, that also tracks, yeah.
I mean, but I feel like there's a lot of examples of animals
with ball sacks that do literally no leaping or jumping.
I don't know how active. Still deal with this?
Like, they're right. Yeah.
They're definitely doing some. Are they further underwater?
Yeah. Or is it different because they
have different, like since they're in a different
substrate, different forces acting on it?
Yeah. So we, I mean, pigs.
Do pigs jump? Are pigs things that jump or do
they just, like, walk around? I mean, I saw a goat in a tree,
so I know they kind of do some stuff.
And they've got huge testicles. Fucking huge.
I don't think pigs are like famously going up into to trees,
but I did just play a video game where at one point you play as a
pig that bounces on a little spring.
And I don't think that's probably an accurate
realization, but like it does, I don't know.
I guess that's what I'm trying to say.
I don't know. I don't know.
Well, that is one of the top hypothesis right now is people
are really questioning the temperature hypothesis that it
seemed a little just so story in a lot of ways and it doesn't
fully make a ton of sense. So again, I don't really care.
One of these articles was like, wow, isn't it?
Well, he then says scrotality totality, which is great.
I appreciate that too. But it was just like, isn't it
crazy that something that we you know, that is we study so much
and we isn't it humbling that a basic part of our bodies remains
a mystery and like, welcome to being a woman, bitch.
Do you have any fucking like, no man, no, like we've only studied
the Dick. Apparently only the Dick, not
the scrotum. Sorry, but like, it's not that.
It's like this is how the rest of us feel, by the way.
It's like we also people are just like, huh?
We don't know quite how the eggs get into the uterine tubes.
They do though, teleport. Just.
Teleport. Yeah, We don't know why
endometriosis is a thing. And you know, you have uterine
tissue all over your internal organs.
Periods are supposed to be hard, sweetheart.
Put a heating pack on, you'll be all right.
So it's it was pretty funny, but I I enjoyed this, this jaunt
through I needed it too, you know, dealing with so many
scrotums and I mean that metaphorically that this was a
fun little. I mean, I feel like it's all
very silly and stupid, but so are balls.
I don't know this idea that they're getting squished and
squeezed too much if they're on the inside of the body and
again, makes more than the temperature thing does because
it just seems like such a big evolutionary investment to
literally give yourself hernias. So like, it does, yes.
It is not a spandrel as far as I would guess.
It has to serve some purpose, right?
Right. Oh my God, ugliest spandrel in
the fuck. I'm just saying it's not for an
attraction sake. I think we can all probably rule
that one out. Nobody's like, oh, there's a
purpose. There's a purpose to that
insanity. Yes, I agree with you there.
I mean, and some people have also said that it's simply like
a trade off thing too, that we are not, we're not fully
understanding what other dynamics are going on or other
organs that are more important to keep him the abdomen.
And therefore it's just a space trade off.
Once the balls get too large or something like that, then they
need to be allocated elsewhere. But the ones that have internal
testes have larger testes than the ones in scrotums.
So that's kind of and maybe when you can produce your junk closer
to this to the end goal, it's you don't need as much.
I don't know, I don't know. Yeah, I guess I hadn't thought
about that either. What if stuff gets stuck in the
tube along the way? You really have to.
An elephant's got a long pathway to travel.
Right, right. I mean, and that's a large
animal, but hyrax also has and a monotrem.
Also keep it close so even body size doesn't seem.
To keep it tight, Yeah, keep it tight.
Yeah, so there's super fun things too.
Anyway, but this all started because of Scrotifera.
Dr. Matt Jones, you probably don't want me to give you a
shout out on this podcast, but I really enjoyed talking to you.
Thank you for teaching me about Scrotifera.
It's been on my mind for six weeks straight.
That's what I got. Thanks so much for listening.
All research was done by the hosts, Amy Atwater and Megan
Wetherell. Our theme song is Unlock Me by
Paraz Ganal. This episode was edited by the
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