February 1, 2022 • 48 mins
What is thirst? In this Stuff to Blow Your Mind series, Robert and Joe dive into the biological, cultural and mythological answers to this broad question.
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Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind, the production of
My Heart Radio. Hey, you welcome to Stuff to Blow
your Mind. My name is Robert Lamb and I'm Joe McCormick.
And today I wanted to start off with a short
reading of a few lines from the Odyssey that will
(00:23):
introduce the subject we're getting into for the next few episodes.
So this is from the Odyssey book eleven. I'm gonna
be reading from the Emily Wilson translation, But this is
a section of the story where Odysseus is describing the
horrors that he witnessed in Hades, and there are different
kinds of horrors, Like some of the horror of Hades
(00:45):
is just a kind of profound, depressing disappointment with when
he's confronted with the reality of how crappy it is
to be dead, you know that, Like he he tries
to talk to a Jax, and Ajax can't even really
say anything. But then there's this other section where he
starts seeing more Dante in Inferno, kind of horrors of
(01:06):
actual tortures, and so he sees King Minos, he sees
a Ryan, he sees Sisyphus famously, you know, in the
futile labor of pushing the boulder up a hill long
you see it rolled down again. But eventually he comes
to a figure called Tantalus. And then here's what Odysseus
says about Tantalus. I saw the pain of Tantalus in
(01:28):
water to his chin so parched, no way to drink.
When that old man bent down towards the water, it
was gone. Some god had dried it up. And at
his feet dark earth appeared. Tall leafy trees hung fruit
above his head, sweet figs and pomegranates and brightly shining
apples and ripe olives. But when he grasped them with
(01:51):
his hands, the wind hurled them away towards the shadowy clouds. Now.
When I look at the contraposition of the two tortures
of Tantalus, you got the And you know he always
wants to reach up to get the delicious fruit from
the tree, but the wind kicks up, it pulls it
out from his hands, and he can't ever get the food.
That's a that's a a torture in Tartarus by starvation,
(02:11):
which is not good. Obviously, starvation is very bad, and
it's probably more expressively phrase the second half of this, uh,
the situation, But it's actually the first half that fills
me with more horror when it talks about how he's
he's standing in water, so it's like, you know, he
feels it lapping around on his skin, but every time
(02:31):
he tries to kneel down to put his face to
it to get a drink, the water just is pulled away,
as if by a tide. The gods dry it up
away from his mouth, and he can't ever have a drink.
To me, that's the more terrifying half of this situation. Yeah, yeah,
I love the image of Tantalus. Is this um this
being that is uh, It's he's like he's suspended between
(02:55):
his desires, between his needs needs or desires, depending on
how you want to frame it here. Right, Well, I
guess this raises questions about the the biology of your
shade in Hades or Tartarus, Like does it actually need
to eat and drink and he can't get it or
is this just some kind of I don't know, psychological
need his soul has. It's not really biological. I guess yeah,
(03:16):
given what we we we believe about the underworld via
other myth cycles, I guess it's the idea that he
doesn't actually need the fruit or the water to live.
If you call this living, he's forever suspended in the
state of of on death and on life. Um, but
but wants to have the water, wants to have the fruit.
(03:38):
Maybe that's the kind of question you're not actually supposed
to bother thinking about this, like the annoying pedantic question
that Plato would bring up. Yeah, I mean well, speaking
of of philosophy, there is the concept of Burden's ass
named for fourteenth century French philosopher gen Burden. This one.
This is a basic idea that also pops up in
the works of Aristotle and al Gazali various other writers.
(04:04):
The more common thirst related version is if you have
a donkey that is both hungry and thirsty, and placed
the equal distance from both food and water, it will
remain immobile and die. Now, this may be apart from
the lesson that the the thought experiment is trying to produce,
But I think that's not necessarily true. I think there
might very well be biological priorities that would place access
(04:27):
to water above access to food. Yeah, it's it's one
of these paradoxes that maybe doesn't. You can't exactly recreate
it in reality and expect it to be quite as
a captivating but uh, abstractly it's it's kind of fascinating.
So as Aristotle put it, quote, a man being just
as hungry as thirsty, and placed in between food and
(04:48):
drink must necessarily remain where he is and starve to death.
So obviously that's not going to be the case. If
you're hungry and thirsty and the waiter brings you your
sandwich and your your cola at the same time, you're
not gonna die. You don't have to give the waiter
special instructions. You will. You work in restaurant industry, Joe.
(05:08):
This is not like they don't tell you this, right.
They don't say, look, don't put the drink in the
food in front of the customer at the same time,
or they will. They will just remain immobile and die.
It is actually broadly considered very important in restaurants to
get people their drinks before you get them their food.
If you bring them food before they get their drinks,
people will get very confused and upset. Well, and uh,
(05:30):
I know, I often hear you know when you're a
lot of times when you're hungry, you're actually thirsty, and therefore,
to avoid and prevent overeating, you want to make sure
you have plenty of liquids as well. So yeah, like,
if I'm going into a restaurant situation, I definitely want
my water first because I feel like I'm gonna I'm
gonna have a more balanced experience eating lunch or dinner there,
(05:52):
you'll certainly have a more pleasant experience. Though actually sorry,
I'm just introducing exceptions to every single thing we say
so far, but does come up in a paper that
I want to look at later. There is a concept
that's been documented widely in animal biology known as dehydration
and do standardrexia, which is essentially the idea that many
animals species, certainly humans and rodents, will naturally restrict their
(06:16):
own food intake in response to dehydration. Again, there are
some exceptions some animals like get their water entirely from
food and so forth. But but but typically, like if
you get rodents and and they're thirsty, they will eat
less at each meal you give them, not saying that's
a way to live your life, though, I mean better
to be hydrated. Well, you know, coming back to mythology
(06:39):
a bit. I thought we might mention just a few
other you know, bits of myth and folklore and legend
and so forth concerning thirst uh, because I feel like,
you know, we we have the sort of mythological echoes
of the basic biological reality, and maybe these can help
and inform and shape our conversation as we move forward. Uh.
(07:00):
So there's one, uh particular story I was taken with
from from from ancient China. It's an ancient story dating
back at least as far as the shan Haijing. This
is the the Fabulous Book of Monsters that we we
did an episode, did a couple of episodes on I
think last year, and have recently or will be rerunning
(07:22):
those episodes very soon. The title is sometimes translated as
the Classic of the Mountains and Seas. Yeah. So there's
a lot of a lot of mythological beings and places
mentioned in the book. Um and Uh, and there's there
is this account of Kuafu. It's a it's a it's
a story that continues to be told today in modern China,
(07:43):
and there have been many versions of it um. According
to U Yang and and Turner in Chinese mythology, basically
what you have in Kuafu is this primordial giant with
two yellow snakes circling his ears and two more yellow
snakes in his hands ends and he's powerful, very powerful, certainly,
but he overestimates his own power, and depending on the
(08:06):
story and the exact telling, he either challenges the Sun
to a race, or he just wants to chase the
Sun's shadow and catch the Sun. I've also read a
version where he wants to prolong the day by catching
the sun, Like if I can just get my hands
on the Sun and then it can't move away, it
can't set, the day will never end. Oh that's a
good plan. Yeah, well, either way it works out. This
(08:28):
giant runs after the Sun, intending to catch it um,
but the Sun stays just ever out of his grasp.
And what happens, well, he grows ever thirstier, So eventually
he just has to stop for a second and he
drinks the yellow river Um. Then he stops and he
drinks drinks another river. But he's still so thirsty that
he heads for the Great Marsh to the north, but
(08:50):
on the way there he collapses. He dies of thirst.
And this is one of those stories that is often
used to explain geography, so they are different. All these
details about what happens to his body once he falls,
what happens to his walking stick or his club once
it falls, what happens to the dirt from his sandals,
you know, they become foothills, that kind of thing. But
(09:11):
it's also a tale about just overreaching. And so the
idea of of this giant chasing the sun is the
idea that yeah, he's powerful, but he thinks he's more
powerful than he is, and it's going to get him
into trouble. Oh that's interesting because to bring it back
to Tantalus, I mean, it's somewhat different, but both stories
have the problem with the character is that they're in
(09:33):
some way brazen or overaudacious in their challenging of celestial
figures or gods. Because the While there are multiple stories
of what Tantalus did in order to deserve this punishment
in tartarus Um, but one of the most commonly received
stories is that Tantalus well, so it's often said that Tantalus,
like uh, shared a table with the god, so he
(09:55):
was a king, but he'd be invited up to Olympus
to to dine with Zeus and Apparently at some point
Tantalus was serving a banquet to the gods, and as
the main course, for some reason, he decided to kill
and serve his own son. So he liked, yeah, that's
that's that's a bad choice. So he yeah, he boils
his own son, serves his meat to the gods. Uh.
(10:18):
It's like this horrible samelier competition, like can you tell
this is my son you're eating? And the gods can
tell they are good semeliers, so they figure it out
and uh. And apparently cannibalism and the killing of ken
were considered among the worst taboos in ancient Greece. So
it's like a story of the guy doing like the worst,
most awful thing you can imagine in order to embarrass
(10:41):
or humiliate the gods, and the gods catch him doing it,
so they send him to this horrible punishment in the afterlife.
And so I do think it's kind of telling that
this is a guy who does like the worst thing
you could possibly imagine doing in in ancient Greek ideas,
like that he commits the worst violence taboos, killing his
own son and trying to get the gods to commit
(11:03):
cannibalism and what what is the punishment for that. It's
eternal unsatiable hunger and thirst. Yeah, yeah, there's this there's
something about thirst, especially that it's just so it's so
primal and it's uh and it's this thing that can
just crescendo towards madness and of course death. Um so
(11:25):
we we we find numerous accounts where the gods become
involved with human thirst. Um. There's an interesting story in
Hindu traditions. This one appears in the Mahaparata. It's about
a desert dwelling sage by the name of Utanka Uh.
And Utanka uh is uh. There are various accounts of
(11:46):
you know, of what he got up to, but uh,
there's basically one of the key ideas here is that
he was witnessed to Krishna's universal form. So this is
the same universal form that shown to Argina during the
famous uh you know, now I am behme death encounter.
Oh yeah, okay. But with Utanka, he's given a special
divine boone. Uh. So he's told whenever he feels thirst,
(12:09):
his thirst will be quenched. Um. So. You also there's
this idea that he's followed by by rain clouds even
in the desert, and so sometimes uh, you'll see these
clouds in real life referred to as Utanka's clouds. Um,
so the clouds sent by the gods to follow him around.
(12:32):
And there's another story too that involves him him thirsting
and the thirst being quenched uh and but water being
sent to him via a member of a lesser cast,
a lower cast, and uh, and then he refuses. As
it turns out the water in question was going to
be uh, the potion of immortality, but he was not
(12:53):
ready to receive it spiritually because he was not willing
to accept it from this individual. Mm hmm. Coming back
to the earlier detail in this where Utanka has given
the boone that whenever he is thirsty, his thirst will
be quenched. I wonder what is the what is the
more specific imagination of that scenario, like that that water
(13:14):
will appear somehow for him to drink, or that there's
a kind of quinching without water, in which case it
kind of makes you think what is quinching because that
when I think of the feeling of quenching thirst, it
is specifically the feeling of like water filling your mouth
and going down your throat. Yeah, yeah, them, It's not
(13:35):
just the idea that we're going to suddenly feel magically.
I'll give across how would that happen? Right? You can't
just turn it off with a switch. Our our one
our primary means of alleviating thirst is to drink water.
And therefore, you know, it's hard to disconnect the too well. Actually,
one of the some of the studies I want to
talk about as we go on in the series have
to do with the what is the relationship between the
(13:56):
feeling of thirst quenching and the hydration of the body.
Not as direct as you might think. Now, another example
of supernatural thirst, and in this case also hunger. Um.
Of course, you have in various Eastern traditions you have
hungry ghosts, and the the ghaki are a type of
hungry ghost in the tradition of Japan, also described as
(14:18):
as always hungry and always thirsty, just monsters of torments.
So they have huge bellies, be steel heads, talons and
so forth, and their home is the barren wasteland realm
of Gakito, and they sometimes drag the dyeing to hell,
but they can be driven out through ceremonies. I think
that they also are often illustrated as having very narrow necks.
(14:40):
So it's like their hunger there is great, their belly
is great, their neck is narrow, like their their throat
is narrow. Their ability to quench uh, their their bodily
hunger and thirst is entirely insufficient. Of course, hungry ghosts
are are you know, widespread again in Eastern traditions. But
but I ran across an interesting tradition from pre Islamic
(15:01):
Arab culture that I had never heard of before that
I thought was really interesting, and it concerns owls. I
was reading Echoes of a Thirsty Owl by T. M. L.
Hammer and published in the Journal of Near Eastern Studies
from so the author here writes that there was an idea,
you know again in the pre Islamic Arab cultures, that
(15:22):
the soul of a bird was quote unquote spread out
through the body of a human being, and when the
human died, um the resulting bird circled the body and
cried out over the grave of the deceased. So the
and then in time this bird grows and it becomes
a savage and shrieking owl, and the owl, of course
(15:42):
haunts the places of death. Well, that almost makes me wonder.
I mean, I think about the spooky movie trope of
having an owl hooting in the darkness in the graveyard.
But I don't know. The more I think about that,
that's probably a coincidence. Well, I mean, owls are are
are are associated with with death and the supernatural throughout
(16:02):
various cultures. You know, because they're they're creatures of the night.
They fly so silently that it's almost like they're not
even there. Um, you know, they have those large eyes,
their their their head appears to have various kind of
humanoid qualities. Uh So, you know, I think there is
some connection there, maybe not not a direct connection, but
(16:23):
a connection via the the the widespread associations and various
cultures between the owl and the and the dead. Okay,
and also the various omens. You know, sometimes in different
cultures the owl is a is a dire omen to behold. Well,
I guess this would depend on the owl species. But
also their vocalizations have to play a role in in
(16:43):
spooky associations. Yeah, yeah, and I think and and also
I mean sometimes owls don't make a sound at all. Again,
either they're flying silently or they're just sitting there silently
just kind of watching and so uh maybe connected to
that that that that it's also said that these owls
may also just sort of check in on sons and
grandsons to see what happens after they have died. Other
(17:06):
traditions say that the owl will return to the grave
once every century. And then there's this idea that in
the event that the deceased might seek vengeance for something
or another, the grave of the dead should be watered
to quote slake the thirst of the dead. Oh wow, yeah, now,
of course, and this we're probably getting into that. Uh
you know something we we hinted out already, the idea
(17:27):
that that thirst takes on so many different forms, and
the water that quenches the thirst, or the liquid the
quenches that thirst takes on so many different forms in
our traditions, like his thirst. Uh, thirst is of course
something we all feel. It's a you know, we all
need water. But depending on how it's written up, you
could you can describe thirst as a as a as
(17:48):
a need, or as a desire, as something that your
will has the ability to overcome or not overcome. Uh,
you know, thirst can be uh portrayed as something positive,
like the third, for knowledge, the thirst for for for
for God. But also thirst can be seen as like
the thirst for for wine, or for blood, or for vengeance. Well, yeah, exactly.
(18:11):
So I was also thinking about the abstract metaphors of
thirst that we use um and what it means to
to choose that word in particular, to to say that
you want something by saying that you thirst for it. So,
in the example of someone who has a thirst for vengeance,
how is that different from just wanting vengeance? To me?
(18:31):
At least in that case, thirst as a metaphor, as
a metaphor for want, implies a kind of irrational desperation
in the in the acquisition behavior is something that will
be sought without hindrance and without reason. Now, obviously that
wouldn't exactly apply to other metaphorical uses of thirst, like
you said, the thirst for knowledge. But again that that
(18:55):
word choice seems to me to imply something different than
somebody just saying somebody likes knowledge or seeks knowledge. It
suggests a kind of primal need. I guess, yeah, And
I guess you also have to factor in that, you know,
for a lot of us we live in in very
water rich environments, and water rich cultures and uh socioeconomic places.
(19:19):
So you know, we we we don't feel true thirst
for the most part, you know, we don't we don't
feel the thirst that is approaching madness and death, um
and the and and then again it comes down to,
like what is the person thirsting for? If you're talking
about somebody feeling a mighty thirst, but you're alluding to
their desire to have an alcoholic beverage, like that's that's
(19:41):
a slightly different thing that just talking about Oh well,
this is this is thirsty work that they're doing, and
you know, implying that they're just they're just building up
a natural uh need for a big draft of water
to satisfy their thirst. It seems when people use thirst
to talk about alcohol, I always detect an air of
of irony and that, yeah, just like it's supposed to
(20:02):
be a little bit funny that you're using it that way, right,
because if you're truly thirsty, alcohol is not what you
should right now. Just to come back to the the
idea of these owls briefly, Apparently, some writings say that
the blood and the brain in the in the deceased
fused together after death to form the owl. Others would
(20:25):
say that it was born of one's bones and that
the owl would then erupt from the head, which I
think is a wonderful and horrifying supernatural uh picture. But
it was a reference in a number of different poems
um by a lot of pre Islamic Arab poets. The
Arabic poet Alan Bari wrote quote, and it is said
(20:49):
that man, when he has killed and his revenge is
not taken, an owl comes out of his grave and
then continues screeching, quench me, quench me, continuing so until
his killer is killed. Whoa anyway that that article is
titled Echoes of a Thirsty Owl UM. If anyone's interested,
I recommend reading that. He also compared, you know, compares
(21:10):
it to various other traditions concerning the owl as some
sort of a supernatural being. He talks a little bit
about about the role of the owl and Greek mythology
and so forth. Than now, we we can't very well
cover a complete cultural history of human thirst here, but
(21:32):
it is worth driving him. The thirst is an important
aspect of history and civilization, UM, in in obvious ways
and maybe sometimes in less obvious ways. I was reading
a article in the Journal of European Archaeology by uh
Slavamil Venhical titled the Archaeology of Thirst, and in it
the author points out that naturally, the human satisfaction of
(21:55):
thirst is an essential part of the human experience, and
it's a but it's of course of great interest in archaeology.
But a number of obstacles have to be overcome. So
first of all, you just have the volatile nature of liquids.
You also have the scant chemical signatures to be found
inside ancient drinking vessels um, also scarce paleo botanical analysis
(22:17):
of those residues. UM. They also mentioned quote the functionally
unspecific nature of most vessels, which I thought was interesting,
reminding me of our our holiday discussion of leg shaped vessels. Yeah,
it's a hard A lot of times people are like,
I don't know what people would put in this leg. Yeah,
Like we can assume they would put oil in it,
(22:39):
you know, but it depending on what the vessel is
and what the culture is, and how much additional information
we have. We might just have to guess and be like, Okay,
it seems like you might drink out of this, or
you might just or maybe this is just restoring some
sort of oil. On top of that, we often have
scant iconographical information. Also, this is a big one, and
this is this apply too far more than just drinking vessels.
(23:02):
But if the vessel is organic in nature, we may
not have any uh surviving examples of what it was.
And on top of that, by and large we tend
to focus on exceptional examples of drinking and storage vessels,
which of course limits study to a very slim part
of a given culture. You know, so it's like a
highly ornate decorative peace that you know, maybe is of
(23:26):
the same shape and basic function is what people would
have in general been using to drink water or store water, etcetera.
But maybe not like maybe it is us. It's more
about looking interesting as opposed to anything else. But the
archaeology of thirst ends up encompassing some very ancient examples um,
including things like neolithic wells. Um Water is the most
(23:50):
basic means of meeting human thirst, and it's taken on
mundane and fantastic connotations at times. But on top of this,
of course humans have come to drink SAPs, but ud
of course various concoctions such as meat and wine and
beer and more. But but I guess water, You know,
water remains the big one obviously. And another idea worth
(24:12):
mentioning in all of this that I was reading about,
um is the idea that, okay, so human thirst is
of course ubiquitous. Everybody is going to thirst. Everyone needs water. Um.
And so if you look back um to to Jewish
and Islamic traditions, you you find in both legal traditions
this idea of the right of thirst um. The the
(24:34):
idea being that like every every every human government by
this law, has this right of thirst uh, to this
right to water via their own thirst. And in Islamic law,
apparently this extended to animals as well. Animals had the
right of thirst, which gave them meant that they had
a right to access water based on their thirst. But
(24:56):
but it's also it's interesting how you know this sort
of this this foreshadows a lot of our modern relationship
with water. The idea that that the right to water
is classified as a basic human right by the United Nations. UM.
But of course, at the same time, uh, not everyone
has equal access to to water and uh. And this
is going to continue to be a problem moving forward,
(25:17):
and of course you can't help, but then take all
of that and relate it back to our metaphorical treatment
of thirst. You know, how does the how does that change?
You know, if you're if you're if you're talking about
thirst in reference to you know, spiritual needs and um
and you know thirst for knowledge, Like, how is that
different if you're if you're expressing that, uh within a
(25:40):
you know, in a place where there where water is plentiful,
where a drinking water is plentiful, or a place where
access is more limited. But I guess before we can
answer any of these questions, we need to back up
quite a bit and just talk about thirst as a
biological reality. What is it and how does it work? Yeah?
And so this was actually rather interesting to me because
(26:01):
it turns out I I knew less about thirst than
I realized. And uh and what we do know about
thurst and what we don't know about thirst are both
pretty interesting. Uh. So I was reading an article called
just called Thirst that was published in Current Biology in
sen by David E. Leeb, Christopher A. Zimmerman, and Zachary A. Night.
(26:26):
And this article is essentially a summary of all the
existing research on thirst. It was, as of the year sixteen,
a sort of perfect primmer catching everybody up on what
do we know about Thurst and what do we not know? Now,
before we get into the meat of that discussion, I guess,
uh to to just cover the very basics, uh, the
first fact before we get into anything else. You are
(26:47):
a water bag. That that is what we are. That
is what all of us are. We we are not
just simple water bags, but our bodies are essentially water
bags over any other material description. All the animal life
that currently lives on land evolved from creatures that used
to live in the ocean, where you're surrounded by water
all the time. And when we evolved to live on land,
(27:07):
we had to create essentially bags that would contain water
to take with us because all of the of the
biological chemistry, the biochemistry of life takes place in water,
in solutions of water, and so as water bags. Uh,
you know, we we are complex autonomous water bags. But
most of those complex autonomous activities actually require that there
(27:32):
be a fairly precise amount of water in the bag
and a fairly precise concentration of various substances things like sodium,
for instance, that pretty precise amounts be dissolved in the
water in the bag, and so various processes of life
are constantly leading to water coming in and out of
(27:55):
the bag. Uh. So there there are several common routes
of water to be added to the bag. Were familiar
with the most common of those, which is drinking fluid,
drinking water or or fluids that are mainly water, or
eating food with water content. And that the second one
they're eating food with water content is less prominent for
(28:16):
humans because you know, we typically drink a glass of
water with food or between meals or whatever. But there
are some animals that basically get almost all of their
water from their food. Yeah. This includes certain desert species
such as the kangaroo rat and the kangaroo mouse, which,
of course, on the planet Iracus becomes the the the
(28:38):
the mouse. Deep. Um, we also have things like the
sand cat, the sand gazelle. Um, and uh, I know,
just in my household, it also seems to include my cat,
who does not seem to drink water at all anymore. Um.
We we have to lean heavily on moist foods to
get to get her her liquids, So feeding her wet food,
(29:01):
adding a little bit of water like sneaking it into
the wet food, and yet if we make the wet
food too wet, she will say, no, it's too much
like water, I will not have it, And then we
put out water for We've tried the fountains, we've tried everything.
The only thing she ever actually drank out of was
a fish tank when we had a fish tank, and
then she would not stop drinking out of the fish tank.
But any other thing we've tried, she hasn't gone for.
(29:23):
And so when she's had some issues before, it's like,
you know, she's clearly dehydrated. In the past, we even
had to had to use an i V to give
her the water. So we we still have a whole
bunch of bags of fluid around in case she has
any any flare ups of her issues. But in terms
of just like drinking straight water, she's not interested at all. Wow. Well,
(29:44):
simultaneously that is kind of fascinating, but also I feel
for her and I feel for you guys that that's
very frustrating. Now we're weird. I mean, everybody seems to
be at a comfortable level right now. She's she seems
to be getting all the liquid she needs through her
her meat paste. But but it's it's weird with cats,
because yeah, I think some people have this experience with
(30:04):
with cats where they really have to be tricked into
drinking water, but others will just drink it on the
fly out of toilets or dripping faucets and so forth. Right,
So all of that is direct water acquisitions. Of course,
you get water from drinking water. You get some smaller
amount of water from eating food that contains water. But
then apparently there's there's a secondary route for water acquisition
(30:26):
by eating food through what's known as metabolic water, which
is when your metabolism oxidizes various energy containing substances that
you eat and produces water in the process. So some
water is created at the molecular level by your metabolism,
(30:46):
and there are some organisms that get a large amount
of their their water content from metabolic water. Humans only
get a very small amount from it. But yeah, I mean,
I think like some desert dwelling organisms and some birds
and stuff it get all or almost all of their
water by by chemical reactions that happen inside their body
(31:07):
after they eat food and turn parts of that food
into water molecules. Now, one of the interesting things I
was reading about some of these desert species um and
at least with some of them. You know, if they're
in a captivity and they are offered water, well, then
when they they their thirst builds up, they will drink
the water. So it's not it's not like everything. I
(31:28):
don't want to imply that anything out there that gets
most of its water through its meat is going to
be like my cat and just refused to drink water.
You know, she has her own issues going on. Yeah,
I'm sure that varies by organism. Okay, but those are
the routes in you've got directly through drinking and eating
and then secondarily through metabolism. But then you've got a
number of routes for water to be to be eliminated.
(31:49):
So you've got urination of course, and then you've got
lost through defecation. You've got evaporation through the lungs of people.
Sometimes don't think about this, but you lose water when
you exhale water. Vapor comes out of your mouth or
out of your nose, and then there is also evaporative
loss of water through the skins just through sweating, so uh,
(32:10):
and then other other more minor things. I mean, obviously,
some extremely tiny amount of water evaporates off of the
liquid on the surface of your eyes and so forth.
But but those are the big ones. The defication is
worth mentioning, probably stressing again because I think most people
are probably familiar with this. But obviously, if one is
in a UH, is suffering from a condition that the
(32:31):
results in you know, um um diarrhea or um, you knows,
some sort of dysenterious situation, you end up losing more
and more water through defecation, and therefore you have to
make sure you're drinking more and more water to make
up for that water loss. Also, just a reminder out
anyone out there, a well fitted and well manufactured still
suit will collect all of this as it leaves your body. UH.
(32:55):
All the routes out will be covered, and you'll lose
no more than a thimble's worth of water per day.
We gotta stress well fitted though. You get the wrong
still suit on there, you're gonna have all kinds of
gaps and things not working right. That's right. You don't
know how to work the straps, and you're not you
don't have that forehead piece on correctly. It's just not
gonna work um at at an optimal level than all right. Well, anyway,
(33:21):
I want to come back to some of the findings
that are summarized in that current biology paper by leave
at all that I mentioned earlier. And again this is
from so there will be more research that we get
into from after that adds to some of these findings.
But this is where we were when this when this
good summary came out. So in the human body, the
(33:41):
brain monitors the body's water content, and when certain thresholds
are reached in the that information monitoring system, it motivates
the body to drink fluids. Of course, it's not only
the decrease of fluid volume in the body that makes
us thirsty. One of the most important things to understand
(34:02):
in the maintenance of the body's water content is the
importance of something known as osmal reality. That's O s
M O L A l I T Y. This is
the concentration of various particles such as electrolytes like sodium,
that are dissolved in the body's water content. And you'll
(34:23):
you'll see this often described as blood osmo reality. It's
basically functionally the same thing. The liquid part of our
blood plasma is roughly water. So when people talk about
blood osmo reality. They're talking about OSM reality of the
body's water content. The brain is actually incredibly sensitive to
changes in blood OSM reality. An increase in just one
(34:47):
percent of of the blood OSM reality can cause an
animal to feel thirst and the author's right quote. This sensation,
in turn, is sufficient to orient and energize all of
an animal's actions towards goal of finding and consuming water. Thus,
the study of thirst is the study of how the
brain performs this remarkable transformation, such that small changes in
(35:10):
the composition of the blood become a potent and specific
motivational drive. Uh And and the more I thought about that,
the more interesting it became that essentially, just sort of
eating a small amount of salt, for example, is enough
to to motivate my brain to change all of my behavior.
(35:31):
Because my osmolality goes up, the salt dissolved in my
body's water content increases in order to balance that out,
my body wants me to go get some more water
to drink, and that I will interrupt whatever I'm doing
to go do it. And we and we dind not
even really think about this. We don't think, Oh, now
my body has need of water, I must go get it.
It's just like, it's just what you do. Yeah. Like,
(35:54):
I mean right here, as we're recording, and I have
a big thermis of water and I just end up
casually sipping on it the whole time. Yeah. Same here.
I always get a nice big glass of water before
we start recording. But but the question would be, why
are our bodies so sensitive to these tiny changes in
osmo reality in the amount of of osmolites dissolved in
the blood. Why would like a one percent increase in
(36:17):
salt concentration really caused that much of a problem. Well,
the authors offer some explanations. They say, first of all,
you've got this thing in your body known as the
electrochemical gradient. The cells in our bodies are selectively permeable
to specific ions quote, resulting in an electrochemical gradient across
(36:39):
the plasma membrane that is exploited for numerous cellular functions.
So this means that there's a difference in the electrical
charge and the concentration of various chemicals on opposite sides
of the membrane that surrounds each of our cells. And
the difference or the gradient here, the fact that it's
different on each side of the membrane is what permits
(37:02):
the transportation of ions across the membrane so that cells
can do things, so that they can send and receive things.
So if you change your blood osmolality, you say, increase
the concentration of salt in the body's water content. You
change this gradient, and you change the water contents inside cells,
(37:22):
and you quote degrade normal cellular function. Now, I was
trying to think of a rough analogy, and here's what
I came up with. This may be very rough, but
it's my best attempt. So when you change your blood
osmolality away from its ideal, I would say your body
sort of becomes like a city that starts having system
wide problems opening and closing doors. Now, is the problems
(37:46):
opening and closing doors of all kinds throughout a city
get worse? Eventually this would just cause myriad diverse problems
throughout the city, much like it would in your body. Well,
that that just sounds like chaos. That just sounds like
like all order is falling out out the window, right,
And you can actually see that the visual representation of
(38:07):
that chaos in a chart that the authors include in
their paper, where it shows what the typical symptoms are
as the blood osmolality goes too far above or below
what it's supposed to be uh and uh. Basically on
both sides, it's sort of a mirror image with a
few differences. So you've got the normal range, but then
you start getting away from it, you get things like irritability, lethargy, nausea,
(38:32):
a taxia, trembling, hypothermia, and then in both cases you
end up in the seizures and death territory. So yeah,
so basically, you know, we have this this thin little
realm of stability, and to either extreme it's just madness
and death. Right, So the body has to very carefully
keep that concentration of osmo lites in the right range,
(38:54):
and if it gets off there there are it will
take drastic measures to get it right again. But then
the authors identify another major reason that the body has
to keep fluid volume and osmalality at the right levels,
which is blood pressure. You know, they say, your body
uses blood to transport oxygen and other essential nutrients to
all of its tissues. Everything of the body. It needs
(39:16):
to get oxygen uh that you know, from the lungs
in the heart, and the blood has to get there
to do its work. If the volume of water in
the body drops below ideal levels, blood volume actually decreases.
There's not enough blood, which means the circulatory system has
to work harder and harder to keep blood pressure up
(39:38):
where it needs to be to get to all the
parts of the body and deliver those nutrients. So, in
addition to maintaining the right concentration of those dissolved things
like sodium, you also just need to have enough water
in your body to keep your blood pressure up to
allow your heart to keep getting blood to all the
parts of the body. It just it kind of comes
back to what you said earlier about it. You know
(39:59):
that we're there's water bags. We are creatures made out
of water, and if we don't have enough water, we
don't have enough of us. Right, Yeah, nothing nothing works
without it anyway. The authors say that the bodies of
animals have evolved to carefully preserve blood volume and blood
OSM reality, and then they describe some of the main
components of this system that we know about. So, first
(40:22):
of all, there are neurons that monitor blood OSM reality
and volume. You've got specially dedicated cells in the central
nervous system, that pay attention to this stuff, and when
they detect a problem, they quote trigger a coordinated set
of autonomic, neuroendocrine, and behavioral responses that defend these parameters
(40:42):
against change. So one of the main measures the body
can take to defend against changes in OSM reality is
modulating kidney function. So as osmolality increases, you get a
surge of anti diuretic hormone, which makes the kidneys change
tack to keep more water inside the body and make
the urine more highly concentrated, make it less deluded with water.
(41:05):
Of course, the kidneys can't do their job alone because
they also have to do other things. In addition to that,
they have to help purge the body of toxic substances
and other kinds of waste, and of course some some
water volume will necessarily be lost in that process. Also,
the body loses water through these other means we mentioned
a minute ago, sweating, breathing, and so forth, So eventually
(41:28):
the body will be forced to consume new water to
restore the balance and the volume of the blood plasma.
So so that's the chemistry and the physiology, but eventually
you have to get to behavior. At some point, the
brain has to trigger behaviors to get new water. In
so an animal thinks I need to drink water. Of course,
this behavior can be costly there, you know, there are
(41:50):
factors working against an animal's motivation to do it because
it might involve spending energy finding and traveling to a
water source. It might involve taking big risks. I mean,
think of all the nature documentaries you've seen when predation
happens at the water's edge, whether it's a crocodile jumping
out of the water or a predator sneaking up while
(42:10):
an animal is distracted by lapping up water. Yeah, and
and some of those predators have been traditionally been human beings,
oh totally. And of course drinking water just involves temporarily
de prioritizing other important things, like you know, in the
natural context, maybe forging for food or pursuing reproduction. But
even think you know, it might force you to get
(42:31):
up from gaming or whatever. Well, I mean, this is
one of those areas again where like with humans, so
many of us are are are fortunate that we never
have to hunt for water. You know, the drinking water
is readily available to us. We have all that we need.
And likewise, through humanum civilization, we we tend to have
(42:52):
the food situation knocked as well. Again, and and ideal circumstances,
you're not going to have to spend um most to
your day foraging for food, which is going to be
the case with many different species of animals, you know,
where most of the day is about just finding the food,
eating the food, and of course there's no there's no
room for anything else. And if you're having to hunt
(43:12):
for extra water along the way, then you're that's getting
in the way potentially of this this vital food hunt. Yeah,
just as an aside, easy access to clean, drinkable running
water is like might go to example of what's good
about modern civilization. You know, there are a lot of
people who kind of demonize modern civilization, and there are
a lot of things about it not to like. But
(43:34):
but easy access to clean water is like, that is
the most unambiguous good thing I can think of, right,
I mean to the to the to the extent that
it's ridiculous in some in many cases you know where
someone might ask, what what is this, what is this
water in your toilet? Well, this is drinking water, the
drinking water that comes into the house. He goes into
(43:55):
the toilet, we just make sure that the water in
there it's perfectly fresh and drinkable. Um, which I guess
is good for the dogs and the cats. But um,
you know certainly that I think you see these various
you know, gray water models that certainly make a lot
more sense, like why should the drinking water be the
water in the toilet. Can't the water from the washing
(44:16):
of my hands be the water in the toilet? Wouldn't
that make more sense? Of course it requires more work, right,
But to come back to the the the wild context,
I mean, obviously there are all these things that would
be factors pushing against your your acquisition of water when
your body needs it. So of course what an animal
needs is intrinsic motivation. Actually, they're demotivating factors that are
(44:38):
just natural parts of the environment. So acquiring water needs
its own intrinsic motivation, hence the motivating desire of thirst.
It is a moment to moment drive to acquire water
that's calibrated by the constantly updated feedback on blood volume
and osmality, though there may also be some other interesting
(44:59):
and more prizing inputs on it that will get to
in a bit Now, the authors point out that thirst
appears to have both positive and negative motivating mechanisms, and
I think you can think about food, food and hunger
as an analogy here, because there's something sort of along
the same line. So you've got positive reinforcement of fluid
drinking behavior by just making drinking water when you're thirsty
(45:22):
feel really good. You know, when you're very thirsty, that
glass of water, it's it's delicious, it's wonderful, it feels great.
And then you've got the negative reinforcement side, which is
that thirst is inherently unpleasant. It is experienced as a
type of discomfort or pain that has to be alleviated
by drinking fluid. So we all know from experience that
(45:43):
these things are true, that you have this positive and
negative reinforcement mechanism within the brain for thirst and the
drinking of water. But what's very interesting is that, at
least at the time of this paper, in how these
two mechanisms of thirst are instantiated in the brain is
still not fully understood. There are some major question marks remaining,
(46:04):
and I think there are at least a few other
studies that we can refer to in subsequent parts of
the series about that where where some ideas have developed
since then, but there's still a lot of questions out there,
and this is This is one of the reasons that
I thought it would be so interesting to pursue Thirst
as a series on the show, because it's surprising that
(46:25):
there are things we still don't know about it. It
seems like one of those things that would be absolutely
totally understood at this point. But but there's some great
outlining questions about thirst and and uh, how we experience thirst,
what are the neural pathways there, how is thirst sated?
And so forth? So maybe we'll have to call it
for this first part here. I know I'm only halfway
(46:46):
through discussing this uh from repaper, but if we go
on through the end of this one, this first episode
is gonna be two hours long or something, So so
maybe we should call it. What do you think, Rob?
I think so, Yeah, I'm actually almost out of water
here and I'm going to have to reef ill. But yeah,
I'm excited to keep going with this. There are a
number of little areas I'm hoping we'll get into the
manipulation of thirst by other organisms the end and life
(47:09):
forms the I want to get back to the taste
of water. Uh, this is something that's always fascinated me.
I mean, granted, water, the taste of of of water
will change depending on where you're getting the water. But
you'll sometimes hear people say, well, I don't like the
taste of water, or we'll think of water as having
no taste at all. Um. I actually found some some
(47:30):
some some papers dealing with this topic a little bit,
so I think they could be fun to discuss people
who don't like the taste of water that is a
telltale sign of vampireism. Just add some red food coloring
to it. Then then you're you're like, oh, this is great,
this is wonderful. Okay, well, all veins to drink from
when we return, all right. Uh. In the meantime, if
(47:51):
you want to check out other episodes of Stuff to
Blow your Mind, you'll find them in the Stuff to
Blow your Mind podcast feed wherever you get your podcast
Core episodes on Tuesdays and Thursday is artifact episodes on Wednesdays,
listener mail on Mondays, and on Fridays would do weird
how cinema. That's our time to set aside most serious
matters and just discuss a weird film Huge thanks as
always to our excellent audio producer Seth Nicholas Johnson. If
(48:13):
you would like to get in touch with us with
feedback on this episode or any other, to suggest a
topic for the future, or just to say hello, you
can email us at contact at stuff to Blow your
Mind dot com. Stuff to Blow Your Mind is production
of I Heart Radio. For more podcasts for My heart Radio,
(48:36):
visit the iHeart Radio app, Apple Podcasts, or wherever you're
listening to your favorite shows.
Welcome to Stuff to Blow Your Mind, the production of
My Heart Radio. Hey, you welcome to Stuff to Blow
your Mind. My name is Robert Lamb and I'm Joe McCormick.
And today I wanted to start off with a short
reading of a few lines from the Odyssey that will
(00:23):
introduce the subject we're getting into for the next few episodes.
So this is from the Odyssey book eleven. I'm gonna
be reading from the Emily Wilson translation, But this is
a section of the story where Odysseus is describing the
horrors that he witnessed in Hades, and there are different
kinds of horrors, Like some of the horror of Hades
(00:45):
is just a kind of profound, depressing disappointment with when
he's confronted with the reality of how crappy it is
to be dead, you know that, Like he he tries
to talk to a Jax, and Ajax can't even really
say anything. But then there's this other section where he
starts seeing more Dante in Inferno, kind of horrors of
(01:06):
actual tortures, and so he sees King Minos, he sees
a Ryan, he sees Sisyphus famously, you know, in the
futile labor of pushing the boulder up a hill long
you see it rolled down again. But eventually he comes
to a figure called Tantalus. And then here's what Odysseus
says about Tantalus. I saw the pain of Tantalus in
(01:28):
water to his chin so parched, no way to drink.
When that old man bent down towards the water, it
was gone. Some god had dried it up. And at
his feet dark earth appeared. Tall leafy trees hung fruit
above his head, sweet figs and pomegranates and brightly shining
apples and ripe olives. But when he grasped them with
(01:51):
his hands, the wind hurled them away towards the shadowy clouds. Now.
When I look at the contraposition of the two tortures
of Tantalus, you got the And you know he always
wants to reach up to get the delicious fruit from
the tree, but the wind kicks up, it pulls it
out from his hands, and he can't ever get the food.
That's a that's a a torture in Tartarus by starvation,
(02:11):
which is not good. Obviously, starvation is very bad, and
it's probably more expressively phrase the second half of this, uh,
the situation, But it's actually the first half that fills
me with more horror when it talks about how he's
he's standing in water, so it's like, you know, he
feels it lapping around on his skin, but every time
(02:31):
he tries to kneel down to put his face to
it to get a drink, the water just is pulled away,
as if by a tide. The gods dry it up
away from his mouth, and he can't ever have a drink.
To me, that's the more terrifying half of this situation. Yeah, yeah,
I love the image of Tantalus. Is this um this
being that is uh, It's he's like he's suspended between
(02:55):
his desires, between his needs needs or desires, depending on
how you want to frame it here. Right, Well, I
guess this raises questions about the the biology of your
shade in Hades or Tartarus, Like does it actually need
to eat and drink and he can't get it or
is this just some kind of I don't know, psychological
need his soul has. It's not really biological. I guess yeah,
(03:16):
given what we we we believe about the underworld via
other myth cycles, I guess it's the idea that he
doesn't actually need the fruit or the water to live.
If you call this living, he's forever suspended in the
state of of on death and on life. Um, but
but wants to have the water, wants to have the fruit.
(03:38):
Maybe that's the kind of question you're not actually supposed
to bother thinking about this, like the annoying pedantic question
that Plato would bring up. Yeah, I mean well, speaking
of of philosophy, there is the concept of Burden's ass
named for fourteenth century French philosopher gen Burden. This one.
This is a basic idea that also pops up in
the works of Aristotle and al Gazali various other writers.
(04:04):
The more common thirst related version is if you have
a donkey that is both hungry and thirsty, and placed
the equal distance from both food and water, it will
remain immobile and die. Now, this may be apart from
the lesson that the the thought experiment is trying to produce,
But I think that's not necessarily true. I think there
might very well be biological priorities that would place access
(04:27):
to water above access to food. Yeah, it's it's one
of these paradoxes that maybe doesn't. You can't exactly recreate
it in reality and expect it to be quite as
a captivating but uh, abstractly it's it's kind of fascinating.
So as Aristotle put it, quote, a man being just
as hungry as thirsty, and placed in between food and
(04:48):
drink must necessarily remain where he is and starve to death.
So obviously that's not going to be the case. If
you're hungry and thirsty and the waiter brings you your
sandwich and your your cola at the same time, you're
not gonna die. You don't have to give the waiter
special instructions. You will. You work in restaurant industry, Joe.
(05:08):
This is not like they don't tell you this, right.
They don't say, look, don't put the drink in the
food in front of the customer at the same time,
or they will. They will just remain immobile and die.
It is actually broadly considered very important in restaurants to
get people their drinks before you get them their food.
If you bring them food before they get their drinks,
people will get very confused and upset. Well, and uh,
(05:30):
I know, I often hear you know when you're a
lot of times when you're hungry, you're actually thirsty, and therefore,
to avoid and prevent overeating, you want to make sure
you have plenty of liquids as well. So yeah, like,
if I'm going into a restaurant situation, I definitely want
my water first because I feel like I'm gonna I'm
gonna have a more balanced experience eating lunch or dinner there,
(05:52):
you'll certainly have a more pleasant experience. Though actually sorry,
I'm just introducing exceptions to every single thing we say
so far, but does come up in a paper that
I want to look at later. There is a concept
that's been documented widely in animal biology known as dehydration
and do standardrexia, which is essentially the idea that many
animals species, certainly humans and rodents, will naturally restrict their
(06:16):
own food intake in response to dehydration. Again, there are
some exceptions some animals like get their water entirely from
food and so forth. But but but typically, like if
you get rodents and and they're thirsty, they will eat
less at each meal you give them, not saying that's
a way to live your life, though, I mean better
to be hydrated. Well, you know, coming back to mythology
(06:39):
a bit. I thought we might mention just a few
other you know, bits of myth and folklore and legend
and so forth concerning thirst uh, because I feel like,
you know, we we have the sort of mythological echoes
of the basic biological reality, and maybe these can help
and inform and shape our conversation as we move forward. Uh.
(07:00):
So there's one, uh particular story I was taken with
from from from ancient China. It's an ancient story dating
back at least as far as the shan Haijing. This
is the the Fabulous Book of Monsters that we we
did an episode, did a couple of episodes on I
think last year, and have recently or will be rerunning
(07:22):
those episodes very soon. The title is sometimes translated as
the Classic of the Mountains and Seas. Yeah. So there's
a lot of a lot of mythological beings and places
mentioned in the book. Um and Uh, and there's there
is this account of Kuafu. It's a it's a it's
a story that continues to be told today in modern China,
(07:43):
and there have been many versions of it um. According
to U Yang and and Turner in Chinese mythology, basically
what you have in Kuafu is this primordial giant with
two yellow snakes circling his ears and two more yellow
snakes in his hands ends and he's powerful, very powerful, certainly,
but he overestimates his own power, and depending on the
(08:06):
story and the exact telling, he either challenges the Sun
to a race, or he just wants to chase the
Sun's shadow and catch the Sun. I've also read a
version where he wants to prolong the day by catching
the sun, Like if I can just get my hands
on the Sun and then it can't move away, it
can't set, the day will never end. Oh that's a
good plan. Yeah, well, either way it works out. This
(08:28):
giant runs after the Sun, intending to catch it um,
but the Sun stays just ever out of his grasp.
And what happens, well, he grows ever thirstier, So eventually
he just has to stop for a second and he
drinks the yellow river Um. Then he stops and he
drinks drinks another river. But he's still so thirsty that
he heads for the Great Marsh to the north, but
(08:50):
on the way there he collapses. He dies of thirst.
And this is one of those stories that is often
used to explain geography, so they are different. All these
details about what happens to his body once he falls,
what happens to his walking stick or his club once
it falls, what happens to the dirt from his sandals,
you know, they become foothills, that kind of thing. But
(09:11):
it's also a tale about just overreaching. And so the
idea of of this giant chasing the sun is the
idea that yeah, he's powerful, but he thinks he's more
powerful than he is, and it's going to get him
into trouble. Oh that's interesting because to bring it back
to Tantalus, I mean, it's somewhat different, but both stories
have the problem with the character is that they're in
(09:33):
some way brazen or overaudacious in their challenging of celestial
figures or gods. Because the While there are multiple stories
of what Tantalus did in order to deserve this punishment
in tartarus Um, but one of the most commonly received
stories is that Tantalus well, so it's often said that Tantalus,
like uh, shared a table with the god, so he
(09:55):
was a king, but he'd be invited up to Olympus
to to dine with Zeus and Apparently at some point
Tantalus was serving a banquet to the gods, and as
the main course, for some reason, he decided to kill
and serve his own son. So he liked, yeah, that's
that's that's a bad choice. So he yeah, he boils
his own son, serves his meat to the gods. Uh.
(10:18):
It's like this horrible samelier competition, like can you tell
this is my son you're eating? And the gods can
tell they are good semeliers, so they figure it out
and uh. And apparently cannibalism and the killing of ken
were considered among the worst taboos in ancient Greece. So
it's like a story of the guy doing like the worst,
most awful thing you can imagine in order to embarrass
(10:41):
or humiliate the gods, and the gods catch him doing it,
so they send him to this horrible punishment in the afterlife.
And so I do think it's kind of telling that
this is a guy who does like the worst thing
you could possibly imagine doing in in ancient Greek ideas,
like that he commits the worst violence taboos, killing his
own son and trying to get the gods to commit
(11:03):
cannibalism and what what is the punishment for that. It's
eternal unsatiable hunger and thirst. Yeah, yeah, there's this there's
something about thirst, especially that it's just so it's so
primal and it's uh and it's this thing that can
just crescendo towards madness and of course death. Um so
(11:25):
we we we find numerous accounts where the gods become
involved with human thirst. Um. There's an interesting story in
Hindu traditions. This one appears in the Mahaparata. It's about
a desert dwelling sage by the name of Utanka Uh.
And Utanka uh is uh. There are various accounts of
(11:46):
you know, of what he got up to, but uh,
there's basically one of the key ideas here is that
he was witnessed to Krishna's universal form. So this is
the same universal form that shown to Argina during the
famous uh you know, now I am behme death encounter.
Oh yeah, okay. But with Utanka, he's given a special
divine boone. Uh. So he's told whenever he feels thirst,
(12:09):
his thirst will be quenched. Um. So. You also there's
this idea that he's followed by by rain clouds even
in the desert, and so sometimes uh, you'll see these
clouds in real life referred to as Utanka's clouds. Um,
so the clouds sent by the gods to follow him around.
(12:32):
And there's another story too that involves him him thirsting
and the thirst being quenched uh and but water being
sent to him via a member of a lesser cast,
a lower cast, and uh, and then he refuses. As
it turns out the water in question was going to
be uh, the potion of immortality, but he was not
(12:53):
ready to receive it spiritually because he was not willing
to accept it from this individual. Mm hmm. Coming back
to the earlier detail in this where Utanka has given
the boone that whenever he is thirsty, his thirst will
be quenched. I wonder what is the what is the
more specific imagination of that scenario, like that that water
(13:14):
will appear somehow for him to drink, or that there's
a kind of quinching without water, in which case it
kind of makes you think what is quinching because that
when I think of the feeling of quenching thirst, it
is specifically the feeling of like water filling your mouth
and going down your throat. Yeah, yeah, them, It's not
(13:35):
just the idea that we're going to suddenly feel magically.
I'll give across how would that happen? Right? You can't
just turn it off with a switch. Our our one
our primary means of alleviating thirst is to drink water.
And therefore, you know, it's hard to disconnect the too well. Actually,
one of the some of the studies I want to
talk about as we go on in the series have
to do with the what is the relationship between the
(13:56):
feeling of thirst quenching and the hydration of the body.
Not as direct as you might think. Now, another example
of supernatural thirst, and in this case also hunger. Um.
Of course, you have in various Eastern traditions you have
hungry ghosts, and the the ghaki are a type of
hungry ghost in the tradition of Japan, also described as
(14:18):
as always hungry and always thirsty, just monsters of torments.
So they have huge bellies, be steel heads, talons and
so forth, and their home is the barren wasteland realm
of Gakito, and they sometimes drag the dyeing to hell,
but they can be driven out through ceremonies. I think
that they also are often illustrated as having very narrow necks.
(14:40):
So it's like their hunger there is great, their belly
is great, their neck is narrow, like their their throat
is narrow. Their ability to quench uh, their their bodily
hunger and thirst is entirely insufficient. Of course, hungry ghosts
are are you know, widespread again in Eastern traditions. But
but I ran across an interesting tradition from pre Islamic
(15:01):
Arab culture that I had never heard of before that
I thought was really interesting, and it concerns owls. I
was reading Echoes of a Thirsty Owl by T. M. L.
Hammer and published in the Journal of Near Eastern Studies
from so the author here writes that there was an idea,
you know again in the pre Islamic Arab cultures, that
(15:22):
the soul of a bird was quote unquote spread out
through the body of a human being, and when the
human died, um the resulting bird circled the body and
cried out over the grave of the deceased. So the
and then in time this bird grows and it becomes
a savage and shrieking owl, and the owl, of course
(15:42):
haunts the places of death. Well, that almost makes me wonder.
I mean, I think about the spooky movie trope of
having an owl hooting in the darkness in the graveyard.
But I don't know. The more I think about that,
that's probably a coincidence. Well, I mean, owls are are
are are associated with with death and the supernatural throughout
(16:02):
various cultures. You know, because they're they're creatures of the night.
They fly so silently that it's almost like they're not
even there. Um, you know, they have those large eyes,
their their their head appears to have various kind of
humanoid qualities. Uh So, you know, I think there is
some connection there, maybe not not a direct connection, but
(16:23):
a connection via the the the widespread associations and various
cultures between the owl and the and the dead. Okay,
and also the various omens. You know, sometimes in different
cultures the owl is a is a dire omen to behold. Well,
I guess this would depend on the owl species. But
also their vocalizations have to play a role in in
(16:43):
spooky associations. Yeah, yeah, and I think and and also
I mean sometimes owls don't make a sound at all. Again,
either they're flying silently or they're just sitting there silently
just kind of watching and so uh maybe connected to
that that that that it's also said that these owls
may also just sort of check in on sons and
grandsons to see what happens after they have died. Other
(17:06):
traditions say that the owl will return to the grave
once every century. And then there's this idea that in
the event that the deceased might seek vengeance for something
or another, the grave of the dead should be watered
to quote slake the thirst of the dead. Oh wow, yeah, now,
of course, and this we're probably getting into that. Uh
you know something we we hinted out already, the idea
(17:27):
that that thirst takes on so many different forms, and
the water that quenches the thirst, or the liquid the
quenches that thirst takes on so many different forms in
our traditions, like his thirst. Uh, thirst is of course
something we all feel. It's a you know, we all
need water. But depending on how it's written up, you
could you can describe thirst as a as a as
(17:48):
a need, or as a desire, as something that your
will has the ability to overcome or not overcome. Uh,
you know, thirst can be uh portrayed as something positive,
like the third, for knowledge, the thirst for for for
for God. But also thirst can be seen as like
the thirst for for wine, or for blood, or for vengeance. Well, yeah, exactly.
(18:11):
So I was also thinking about the abstract metaphors of
thirst that we use um and what it means to
to choose that word in particular, to to say that
you want something by saying that you thirst for it. So,
in the example of someone who has a thirst for vengeance,
how is that different from just wanting vengeance? To me?
(18:31):
At least in that case, thirst as a metaphor, as
a metaphor for want, implies a kind of irrational desperation
in the in the acquisition behavior is something that will
be sought without hindrance and without reason. Now, obviously that
wouldn't exactly apply to other metaphorical uses of thirst, like
you said, the thirst for knowledge. But again that that
(18:55):
word choice seems to me to imply something different than
somebody just saying somebody likes knowledge or seeks knowledge. It
suggests a kind of primal need. I guess, yeah, And
I guess you also have to factor in that, you know,
for a lot of us we live in in very
water rich environments, and water rich cultures and uh socioeconomic places.
(19:19):
So you know, we we we don't feel true thirst
for the most part, you know, we don't we don't
feel the thirst that is approaching madness and death, um
and the and and then again it comes down to,
like what is the person thirsting for? If you're talking
about somebody feeling a mighty thirst, but you're alluding to
their desire to have an alcoholic beverage, like that's that's
(19:41):
a slightly different thing that just talking about Oh well,
this is this is thirsty work that they're doing, and
you know, implying that they're just they're just building up
a natural uh need for a big draft of water
to satisfy their thirst. It seems when people use thirst
to talk about alcohol, I always detect an air of
of irony and that, yeah, just like it's supposed to
(20:02):
be a little bit funny that you're using it that way, right,
because if you're truly thirsty, alcohol is not what you
should right now. Just to come back to the the
idea of these owls briefly, Apparently, some writings say that
the blood and the brain in the in the deceased
fused together after death to form the owl. Others would
(20:25):
say that it was born of one's bones and that
the owl would then erupt from the head, which I
think is a wonderful and horrifying supernatural uh picture. But
it was a reference in a number of different poems
um by a lot of pre Islamic Arab poets. The
Arabic poet Alan Bari wrote quote, and it is said
(20:49):
that man, when he has killed and his revenge is
not taken, an owl comes out of his grave and
then continues screeching, quench me, quench me, continuing so until
his killer is killed. Whoa anyway that that article is
titled Echoes of a Thirsty Owl UM. If anyone's interested,
I recommend reading that. He also compared, you know, compares
(21:10):
it to various other traditions concerning the owl as some
sort of a supernatural being. He talks a little bit
about about the role of the owl and Greek mythology
and so forth. Than now, we we can't very well
cover a complete cultural history of human thirst here, but
(21:32):
it is worth driving him. The thirst is an important
aspect of history and civilization, UM, in in obvious ways
and maybe sometimes in less obvious ways. I was reading
a article in the Journal of European Archaeology by uh
Slavamil Venhical titled the Archaeology of Thirst, and in it
the author points out that naturally, the human satisfaction of
(21:55):
thirst is an essential part of the human experience, and
it's a but it's of course of great interest in archaeology.
But a number of obstacles have to be overcome. So
first of all, you just have the volatile nature of liquids.
You also have the scant chemical signatures to be found
inside ancient drinking vessels um, also scarce paleo botanical analysis
(22:17):
of those residues. UM. They also mentioned quote the functionally
unspecific nature of most vessels, which I thought was interesting,
reminding me of our our holiday discussion of leg shaped vessels. Yeah,
it's a hard A lot of times people are like,
I don't know what people would put in this leg. Yeah,
Like we can assume they would put oil in it,
(22:39):
you know, but it depending on what the vessel is
and what the culture is, and how much additional information
we have. We might just have to guess and be like, Okay,
it seems like you might drink out of this, or
you might just or maybe this is just restoring some
sort of oil. On top of that, we often have
scant iconographical information. Also, this is a big one, and
this is this apply too far more than just drinking vessels.
(23:02):
But if the vessel is organic in nature, we may
not have any uh surviving examples of what it was.
And on top of that, by and large we tend
to focus on exceptional examples of drinking and storage vessels,
which of course limits study to a very slim part
of a given culture. You know, so it's like a
highly ornate decorative peace that you know, maybe is of
(23:26):
the same shape and basic function is what people would
have in general been using to drink water or store water, etcetera.
But maybe not like maybe it is us. It's more
about looking interesting as opposed to anything else. But the
archaeology of thirst ends up encompassing some very ancient examples um,
including things like neolithic wells. Um Water is the most
(23:50):
basic means of meeting human thirst, and it's taken on
mundane and fantastic connotations at times. But on top of this,
of course humans have come to drink SAPs, but ud
of course various concoctions such as meat and wine and
beer and more. But but I guess water, You know,
water remains the big one obviously. And another idea worth
(24:12):
mentioning in all of this that I was reading about,
um is the idea that, okay, so human thirst is
of course ubiquitous. Everybody is going to thirst. Everyone needs water. Um.
And so if you look back um to to Jewish
and Islamic traditions, you you find in both legal traditions
this idea of the right of thirst um. The the
(24:34):
idea being that like every every every human government by
this law, has this right of thirst uh, to this
right to water via their own thirst. And in Islamic law,
apparently this extended to animals as well. Animals had the
right of thirst, which gave them meant that they had
a right to access water based on their thirst. But
(24:56):
but it's also it's interesting how you know this sort
of this this foreshadows a lot of our modern relationship
with water. The idea that that the right to water
is classified as a basic human right by the United Nations. UM.
But of course, at the same time, uh, not everyone
has equal access to to water and uh. And this
is going to continue to be a problem moving forward,
(25:17):
and of course you can't help, but then take all
of that and relate it back to our metaphorical treatment
of thirst. You know, how does the how does that change?
You know, if you're if you're if you're talking about
thirst in reference to you know, spiritual needs and um
and you know thirst for knowledge, Like, how is that
different if you're if you're expressing that, uh within a
(25:40):
you know, in a place where there where water is plentiful,
where a drinking water is plentiful, or a place where
access is more limited. But I guess before we can
answer any of these questions, we need to back up
quite a bit and just talk about thirst as a
biological reality. What is it and how does it work? Yeah?
And so this was actually rather interesting to me because
(26:01):
it turns out I I knew less about thirst than
I realized. And uh and what we do know about
thurst and what we don't know about thirst are both
pretty interesting. Uh. So I was reading an article called
just called Thirst that was published in Current Biology in
sen by David E. Leeb, Christopher A. Zimmerman, and Zachary A. Night.
(26:26):
And this article is essentially a summary of all the
existing research on thirst. It was, as of the year sixteen,
a sort of perfect primmer catching everybody up on what
do we know about Thurst and what do we not know? Now,
before we get into the meat of that discussion, I guess,
uh to to just cover the very basics, uh, the
first fact before we get into anything else. You are
(26:47):
a water bag. That that is what we are. That
is what all of us are. We we are not
just simple water bags, but our bodies are essentially water
bags over any other material description. All the animal life
that currently lives on land evolved from creatures that used
to live in the ocean, where you're surrounded by water
all the time. And when we evolved to live on land,
(27:07):
we had to create essentially bags that would contain water
to take with us because all of the of the
biological chemistry, the biochemistry of life takes place in water,
in solutions of water, and so as water bags. Uh,
you know, we we are complex autonomous water bags. But
most of those complex autonomous activities actually require that there
(27:32):
be a fairly precise amount of water in the bag
and a fairly precise concentration of various substances things like sodium,
for instance, that pretty precise amounts be dissolved in the
water in the bag, and so various processes of life
are constantly leading to water coming in and out of
(27:55):
the bag. Uh. So there there are several common routes
of water to be added to the bag. Were familiar
with the most common of those, which is drinking fluid,
drinking water or or fluids that are mainly water, or
eating food with water content. And that the second one
they're eating food with water content is less prominent for
(28:16):
humans because you know, we typically drink a glass of
water with food or between meals or whatever. But there
are some animals that basically get almost all of their
water from their food. Yeah. This includes certain desert species
such as the kangaroo rat and the kangaroo mouse, which,
of course, on the planet Iracus becomes the the the
(28:38):
the mouse. Deep. Um, we also have things like the
sand cat, the sand gazelle. Um, and uh, I know,
just in my household, it also seems to include my cat,
who does not seem to drink water at all anymore. Um.
We we have to lean heavily on moist foods to
get to get her her liquids, So feeding her wet food,
(29:01):
adding a little bit of water like sneaking it into
the wet food, and yet if we make the wet
food too wet, she will say, no, it's too much
like water, I will not have it, And then we
put out water for We've tried the fountains, we've tried everything.
The only thing she ever actually drank out of was
a fish tank when we had a fish tank, and
then she would not stop drinking out of the fish tank.
But any other thing we've tried, she hasn't gone for.
(29:23):
And so when she's had some issues before, it's like,
you know, she's clearly dehydrated. In the past, we even
had to had to use an i V to give
her the water. So we we still have a whole
bunch of bags of fluid around in case she has
any any flare ups of her issues. But in terms
of just like drinking straight water, she's not interested at all. Wow. Well,
(29:44):
simultaneously that is kind of fascinating, but also I feel
for her and I feel for you guys that that's
very frustrating. Now we're weird. I mean, everybody seems to
be at a comfortable level right now. She's she seems
to be getting all the liquid she needs through her
her meat paste. But but it's it's weird with cats,
because yeah, I think some people have this experience with
(30:04):
with cats where they really have to be tricked into
drinking water, but others will just drink it on the
fly out of toilets or dripping faucets and so forth. Right,
So all of that is direct water acquisitions. Of course,
you get water from drinking water. You get some smaller
amount of water from eating food that contains water. But
then apparently there's there's a secondary route for water acquisition
(30:26):
by eating food through what's known as metabolic water, which
is when your metabolism oxidizes various energy containing substances that
you eat and produces water in the process. So some
water is created at the molecular level by your metabolism,
(30:46):
and there are some organisms that get a large amount
of their their water content from metabolic water. Humans only
get a very small amount from it. But yeah, I mean,
I think like some desert dwelling organisms and some birds
and stuff it get all or almost all of their
water by by chemical reactions that happen inside their body
(31:07):
after they eat food and turn parts of that food
into water molecules. Now, one of the interesting things I
was reading about some of these desert species um and
at least with some of them. You know, if they're
in a captivity and they are offered water, well, then
when they they their thirst builds up, they will drink
the water. So it's not it's not like everything. I
(31:28):
don't want to imply that anything out there that gets
most of its water through its meat is going to
be like my cat and just refused to drink water.
You know, she has her own issues going on. Yeah,
I'm sure that varies by organism. Okay, but those are
the routes in you've got directly through drinking and eating
and then secondarily through metabolism. But then you've got a
number of routes for water to be to be eliminated.
(31:49):
So you've got urination of course, and then you've got
lost through defecation. You've got evaporation through the lungs of people.
Sometimes don't think about this, but you lose water when
you exhale water. Vapor comes out of your mouth or
out of your nose, and then there is also evaporative
loss of water through the skins just through sweating, so uh,
(32:10):
and then other other more minor things. I mean, obviously,
some extremely tiny amount of water evaporates off of the
liquid on the surface of your eyes and so forth.
But but those are the big ones. The defication is
worth mentioning, probably stressing again because I think most people
are probably familiar with this. But obviously, if one is
in a UH, is suffering from a condition that the
(32:31):
results in you know, um um diarrhea or um, you knows,
some sort of dysenterious situation, you end up losing more
and more water through defecation, and therefore you have to
make sure you're drinking more and more water to make
up for that water loss. Also, just a reminder out
anyone out there, a well fitted and well manufactured still
suit will collect all of this as it leaves your body. UH.
(32:55):
All the routes out will be covered, and you'll lose
no more than a thimble's worth of water per day.
We gotta stress well fitted though. You get the wrong
still suit on there, you're gonna have all kinds of
gaps and things not working right. That's right. You don't
know how to work the straps, and you're not you
don't have that forehead piece on correctly. It's just not
gonna work um at at an optimal level than all right. Well, anyway,
(33:21):
I want to come back to some of the findings
that are summarized in that current biology paper by leave
at all that I mentioned earlier. And again this is
from so there will be more research that we get
into from after that adds to some of these findings.
But this is where we were when this when this
good summary came out. So in the human body, the
(33:41):
brain monitors the body's water content, and when certain thresholds
are reached in the that information monitoring system, it motivates
the body to drink fluids. Of course, it's not only
the decrease of fluid volume in the body that makes
us thirsty. One of the most important things to understand
(34:02):
in the maintenance of the body's water content is the
importance of something known as osmal reality. That's O s
M O L A l I T Y. This is
the concentration of various particles such as electrolytes like sodium,
that are dissolved in the body's water content. And you'll
(34:23):
you'll see this often described as blood osmo reality. It's
basically functionally the same thing. The liquid part of our
blood plasma is roughly water. So when people talk about
blood osmo reality. They're talking about OSM reality of the
body's water content. The brain is actually incredibly sensitive to
changes in blood OSM reality. An increase in just one
(34:47):
percent of of the blood OSM reality can cause an
animal to feel thirst and the author's right quote. This sensation,
in turn, is sufficient to orient and energize all of
an animal's actions towards goal of finding and consuming water. Thus,
the study of thirst is the study of how the
brain performs this remarkable transformation, such that small changes in
(35:10):
the composition of the blood become a potent and specific
motivational drive. Uh And and the more I thought about that,
the more interesting it became that essentially, just sort of
eating a small amount of salt, for example, is enough
to to motivate my brain to change all of my behavior.
(35:31):
Because my osmolality goes up, the salt dissolved in my
body's water content increases in order to balance that out,
my body wants me to go get some more water
to drink, and that I will interrupt whatever I'm doing
to go do it. And we and we dind not
even really think about this. We don't think, Oh, now
my body has need of water, I must go get it.
It's just like, it's just what you do. Yeah. Like,
(35:54):
I mean right here, as we're recording, and I have
a big thermis of water and I just end up
casually sipping on it the whole time. Yeah. Same here.
I always get a nice big glass of water before
we start recording. But but the question would be, why
are our bodies so sensitive to these tiny changes in
osmo reality in the amount of of osmolites dissolved in
the blood. Why would like a one percent increase in
(36:17):
salt concentration really caused that much of a problem. Well,
the authors offer some explanations. They say, first of all,
you've got this thing in your body known as the
electrochemical gradient. The cells in our bodies are selectively permeable
to specific ions quote, resulting in an electrochemical gradient across
(36:39):
the plasma membrane that is exploited for numerous cellular functions.
So this means that there's a difference in the electrical
charge and the concentration of various chemicals on opposite sides
of the membrane that surrounds each of our cells. And
the difference or the gradient here, the fact that it's
different on each side of the membrane is what permits
(37:02):
the transportation of ions across the membrane so that cells
can do things, so that they can send and receive things.
So if you change your blood osmolality, you say, increase
the concentration of salt in the body's water content. You
change this gradient, and you change the water contents inside cells,
(37:22):
and you quote degrade normal cellular function. Now, I was
trying to think of a rough analogy, and here's what
I came up with. This may be very rough, but
it's my best attempt. So when you change your blood
osmolality away from its ideal, I would say your body
sort of becomes like a city that starts having system
wide problems opening and closing doors. Now, is the problems
(37:46):
opening and closing doors of all kinds throughout a city
get worse? Eventually this would just cause myriad diverse problems
throughout the city, much like it would in your body. Well,
that that just sounds like chaos. That just sounds like
like all order is falling out out the window, right,
And you can actually see that the visual representation of
(38:07):
that chaos in a chart that the authors include in
their paper, where it shows what the typical symptoms are
as the blood osmolality goes too far above or below
what it's supposed to be uh and uh. Basically on
both sides, it's sort of a mirror image with a
few differences. So you've got the normal range, but then
you start getting away from it, you get things like irritability, lethargy, nausea,
(38:32):
a taxia, trembling, hypothermia, and then in both cases you
end up in the seizures and death territory. So yeah,
so basically, you know, we have this this thin little
realm of stability, and to either extreme it's just madness
and death. Right, So the body has to very carefully
keep that concentration of osmo lites in the right range,
(38:54):
and if it gets off there there are it will
take drastic measures to get it right again. But then
the authors identify another major reason that the body has
to keep fluid volume and osmalality at the right levels,
which is blood pressure. You know, they say, your body
uses blood to transport oxygen and other essential nutrients to
all of its tissues. Everything of the body. It needs
(39:16):
to get oxygen uh that you know, from the lungs
in the heart, and the blood has to get there
to do its work. If the volume of water in
the body drops below ideal levels, blood volume actually decreases.
There's not enough blood, which means the circulatory system has
to work harder and harder to keep blood pressure up
(39:38):
where it needs to be to get to all the
parts of the body and deliver those nutrients. So, in
addition to maintaining the right concentration of those dissolved things
like sodium, you also just need to have enough water
in your body to keep your blood pressure up to
allow your heart to keep getting blood to all the
parts of the body. It just it kind of comes
back to what you said earlier about it. You know
(39:59):
that we're there's water bags. We are creatures made out
of water, and if we don't have enough water, we
don't have enough of us. Right, Yeah, nothing nothing works
without it anyway. The authors say that the bodies of
animals have evolved to carefully preserve blood volume and blood
OSM reality, and then they describe some of the main
components of this system that we know about. So, first
(40:22):
of all, there are neurons that monitor blood OSM reality
and volume. You've got specially dedicated cells in the central
nervous system, that pay attention to this stuff, and when
they detect a problem, they quote trigger a coordinated set
of autonomic, neuroendocrine, and behavioral responses that defend these parameters
(40:42):
against change. So one of the main measures the body
can take to defend against changes in OSM reality is
modulating kidney function. So as osmolality increases, you get a
surge of anti diuretic hormone, which makes the kidneys change
tack to keep more water inside the body and make
the urine more highly concentrated, make it less deluded with water.
(41:05):
Of course, the kidneys can't do their job alone because
they also have to do other things. In addition to that,
they have to help purge the body of toxic substances
and other kinds of waste, and of course some some
water volume will necessarily be lost in that process. Also,
the body loses water through these other means we mentioned
a minute ago, sweating, breathing, and so forth, So eventually
(41:28):
the body will be forced to consume new water to
restore the balance and the volume of the blood plasma.
So so that's the chemistry and the physiology, but eventually
you have to get to behavior. At some point, the
brain has to trigger behaviors to get new water. In
so an animal thinks I need to drink water. Of course,
this behavior can be costly there, you know, there are
(41:50):
factors working against an animal's motivation to do it because
it might involve spending energy finding and traveling to a
water source. It might involve taking big risks. I mean,
think of all the nature documentaries you've seen when predation
happens at the water's edge, whether it's a crocodile jumping
out of the water or a predator sneaking up while
(42:10):
an animal is distracted by lapping up water. Yeah, and
and some of those predators have been traditionally been human beings,
oh totally. And of course drinking water just involves temporarily
de prioritizing other important things, like you know, in the
natural context, maybe forging for food or pursuing reproduction. But
even think you know, it might force you to get
(42:31):
up from gaming or whatever. Well, I mean, this is
one of those areas again where like with humans, so
many of us are are are fortunate that we never
have to hunt for water. You know, the drinking water
is readily available to us. We have all that we need.
And likewise, through humanum civilization, we we tend to have
(42:52):
the food situation knocked as well. Again, and and ideal circumstances,
you're not going to have to spend um most to
your day foraging for food, which is going to be
the case with many different species of animals, you know,
where most of the day is about just finding the food,
eating the food, and of course there's no there's no
room for anything else. And if you're having to hunt
(43:12):
for extra water along the way, then you're that's getting
in the way potentially of this this vital food hunt. Yeah,
just as an aside, easy access to clean, drinkable running
water is like might go to example of what's good
about modern civilization. You know, there are a lot of
people who kind of demonize modern civilization, and there are
a lot of things about it not to like. But
(43:34):
but easy access to clean water is like, that is
the most unambiguous good thing I can think of, right,
I mean to the to the to the extent that
it's ridiculous in some in many cases you know where
someone might ask, what what is this, what is this
water in your toilet? Well, this is drinking water, the
drinking water that comes into the house. He goes into
(43:55):
the toilet, we just make sure that the water in
there it's perfectly fresh and drinkable. Um, which I guess
is good for the dogs and the cats. But um,
you know certainly that I think you see these various
you know, gray water models that certainly make a lot
more sense, like why should the drinking water be the
water in the toilet. Can't the water from the washing
(44:16):
of my hands be the water in the toilet? Wouldn't
that make more sense? Of course it requires more work, right,
But to come back to the the the wild context,
I mean, obviously there are all these things that would
be factors pushing against your your acquisition of water when
your body needs it. So of course what an animal
needs is intrinsic motivation. Actually, they're demotivating factors that are
(44:38):
just natural parts of the environment. So acquiring water needs
its own intrinsic motivation, hence the motivating desire of thirst.
It is a moment to moment drive to acquire water
that's calibrated by the constantly updated feedback on blood volume
and osmality, though there may also be some other interesting
(44:59):
and more prizing inputs on it that will get to
in a bit Now, the authors point out that thirst
appears to have both positive and negative motivating mechanisms, and
I think you can think about food, food and hunger
as an analogy here, because there's something sort of along
the same line. So you've got positive reinforcement of fluid
drinking behavior by just making drinking water when you're thirsty
(45:22):
feel really good. You know, when you're very thirsty, that
glass of water, it's it's delicious, it's wonderful, it feels great.
And then you've got the negative reinforcement side, which is
that thirst is inherently unpleasant. It is experienced as a
type of discomfort or pain that has to be alleviated
by drinking fluid. So we all know from experience that
(45:43):
these things are true, that you have this positive and
negative reinforcement mechanism within the brain for thirst and the
drinking of water. But what's very interesting is that, at
least at the time of this paper, in how these
two mechanisms of thirst are instantiated in the brain is
still not fully understood. There are some major question marks remaining,
(46:04):
and I think there are at least a few other
studies that we can refer to in subsequent parts of
the series about that where where some ideas have developed
since then, but there's still a lot of questions out there,
and this is This is one of the reasons that
I thought it would be so interesting to pursue Thirst
as a series on the show, because it's surprising that
(46:25):
there are things we still don't know about it. It
seems like one of those things that would be absolutely
totally understood at this point. But but there's some great
outlining questions about thirst and and uh, how we experience thirst,
what are the neural pathways there, how is thirst sated?
And so forth? So maybe we'll have to call it
for this first part here. I know I'm only halfway
(46:46):
through discussing this uh from repaper, but if we go
on through the end of this one, this first episode
is gonna be two hours long or something, So so
maybe we should call it. What do you think, Rob?
I think so, Yeah, I'm actually almost out of water
here and I'm going to have to reef ill. But yeah,
I'm excited to keep going with this. There are a
number of little areas I'm hoping we'll get into the
manipulation of thirst by other organisms the end and life
(47:09):
forms the I want to get back to the taste
of water. Uh, this is something that's always fascinated me.
I mean, granted, water, the taste of of of water
will change depending on where you're getting the water. But
you'll sometimes hear people say, well, I don't like the
taste of water, or we'll think of water as having
no taste at all. Um. I actually found some some
(47:30):
some some papers dealing with this topic a little bit,
so I think they could be fun to discuss people
who don't like the taste of water that is a
telltale sign of vampireism. Just add some red food coloring
to it. Then then you're you're like, oh, this is great,
this is wonderful. Okay, well, all veins to drink from
when we return, all right. Uh. In the meantime, if
(47:51):
you want to check out other episodes of Stuff to
Blow your Mind, you'll find them in the Stuff to
Blow your Mind podcast feed wherever you get your podcast
Core episodes on Tuesdays and Thursday is artifact episodes on Wednesdays,
listener mail on Mondays, and on Fridays would do weird
how cinema. That's our time to set aside most serious
matters and just discuss a weird film Huge thanks as
always to our excellent audio producer Seth Nicholas Johnson. If
(48:13):
you would like to get in touch with us with
feedback on this episode or any other, to suggest a
topic for the future, or just to say hello, you
can email us at contact at stuff to Blow your
Mind dot com. Stuff to Blow Your Mind is production
of I Heart Radio. For more podcasts for My heart Radio,
(48:36):
visit the iHeart Radio app, Apple Podcasts, or wherever you're
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