Brain Soup and Liquid Brains

Is there ever a good scientific reason to turn brains into soup? What does all of this have to do with the concept of “liquid brains?” Robert and Joe explore on Stuff to Blow Your Mind. 

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Episode Transcript

Speaker 1 (00:03):
Welcome Stuff to Blow Your Mind, a production of I
Heart Radios How Stuff Works. Hey, you, welcome to Stuff
to Blow your Mind. My name is Robert Lamb and
I'm Joe McCormick. Joe. What what kind of image enters
your head when I say the words brain soup? Brain soup?

(00:24):
This is a Green Day song, isn't it? Is it?
I'm having trouble making soup? Is it? I don't know.
I'm not. I'm not. I'm not a sound dukie, right,
I only know like Green Day songs. I think I'm
getting this wrong. Uh No. I also think of there's
a horrible scene in Indiana Jones and the Temple of
Doom where they're they're eating all kinds of weird foods

(00:47):
that are parts of animals that you shouldn't eat, but
why not. But one of those parts is they eat
a monkey brain. I don't think that's supposed to be soup.
By the way, one of my favorite things on the
Internet is a total tangent is uh is? Franchise specific
Wiki entries for inanimate objects allow me to explain. So

(01:10):
there is like an Indiana Jones wiki that's just a
website out there. It's got entries on it for all
the characters minor characters in Indiana Jones movies, all the
adventures he went on. But then also they're just entries
because it's a wiki of just objects that appear in
the Indiana Jones movies. So this will include like individual
pages for each course of the meal in Indiana Jones

(01:31):
and the Temple of Doom. And one of them, the
one that's got all the snakes in it, is called
Coiled Wriggley's. So wait, is it just it's just about
a fictional food or is it attempting to draw lines
between these outrageous and you know, like shock oriented foods
and in some actual traditions, because that if they're not
doing it, that would actually be kind of a fun
thing to do, to sort of take the shock that

(01:54):
they're that they're trying to utilize in that scene and say,
we'll hold on. Actually, here's some actual culinary traditions that
are not really that shocking. Uh no, it's not at
all that informative or mind opening. Just let me allow
me to quote directly from the page for Coiled Wriggles.
Coiled Wriggley is also known as Snakes Surprise, was a
dish served at the Guardian of Tradition dinner given at

(02:16):
Pancok Palace in nine thirty five. As the second course,
it was live baby eels stuffed inside a moist boa constrictor.
One of the guests at the dinner, a merchant, was
very pleased when the dish was served. Another guest enjoyed
the eels with great gusto. I have not seen that
film in a very long time. I really don't know
how it would would hold up. Some elements certainly do not.

(02:39):
You know, I should point out that, like you know,
talking about brain soup, actual brain soup does exist. Do
you have, you know, various pork brain soups, etcetera. And
even though I'm a I'm a pet scutarian these days,
I wouldn't order pork brain soup at a restaurant. I
looked at some photos and it looks perfectly delicious and
not at all weird. Uh So I just want to
drive that home regarding uh the consumption of of brain

(03:03):
based soups before I bring up something that comes to
my mind when I when I hear brain soup, and
what came into my mind when I heard it recently?
I instantly think back to the two film it came
from Hollywood. Oh, yes, so this was this is a film.
It's it's I think you can watch most of it
on YouTube these days. But as Dan Ackroyd, John Candy

(03:25):
Cheech and Chong Gilda Radner, that whole crew, and sort
of before Mystery Science Theater, there was this movie. It
was just a clip show of like bad sci fi
films and stuff, with the hosts of the movie making
jokes about them. Yeah, and so a lot of trailer clips,
a lot of weird clips, And there's a whole section
that I that I loved as a kid about brains.

(03:47):
You know, all these weird fifties and sixties brain monster films,
which which I think are probably expressing a certain amount
of anxiety regarding like post war advances in neuroscience and
the sort of existential conundros that are raised, you know, like,
am I just a brain? What does it mean to
be just a brain? Will a brain jump out of
someone's head and attack me with its tentacles? There was

(04:08):
a lot of revolutionary neuroscience going on in the nineteen fifties,
and yeah, I can see exactly why people would be
concerned about this kind of thing, though some of them
are just more like I think there's one called like
the brain from Planet Rouse or something that, yeah, just
giant brains swarming at people. So I don't know exactly
how much that plays on anxieties about neurology, but I

(04:29):
mean I get that that what I really get a
sense of it when I see clips from Fiend Without
a Face, because as we have the fabulous stop motion
brains and kind of like spinal column tentacles, yeah, all
over the furniture. We just sprayed for brains last week.
But anyway, this particular segment on brains was introduced by

(04:51):
dan ackroyd Uh and he's he's he's in this this scene.
It's like he's in a butcher's shop and he's playing
a maniacal Perhaps he's supposed to be like a mad
brain scientist or a brain butcher, or like a brain
addict cannibal. It's it's kind of hard to say, it's
not entirely clear, but it's it's silly and it's gross

(05:12):
and it's a I was tempted to play a clip
from it here, but it's just so over the top
that I don't I don't think it would translate well
to an audio only environment. You are correctly capturing here
the strangeness of the premise for the sketch in the movie.
I don't just blithely throw around the phrase cocaine fuel.

(05:33):
But there there are some cases where you get you
get a suspicion. But also in that scene, I remember
dan Ackroyd is doing a voice that sounds a lot
like a Monty Python voice, and he sounds like the
leader of the Knights who say knee. Yes he does.
It's that kind of like ridiculous cartoonish voice. Oh yeah,
the whole segment is is fabulous, all right, But all

(05:55):
this sort of these sort of visceral reactions to the
idea of brain soup aside, we are not going to
be talking about eating brains today on the show. We're
going to talk about the very real practice, the scientific
practice of making brain soup to better understand the neural
power of animal brains. Well, I am very intrigued already now, Robert,

(06:19):
I know this. The subject is not coming out of nowhere.
This is inspired by something that you just saw when
you were at the World Science Festival in New York
City last week. That's right. Yeah, I just got back
and uh yeah. This is held every the last week
of May every year, and as usual I got to
hear some of the world's leading scientists and thinkers discussed
a number of exciting topics. And one of the talks
I attended was rethinking thinking how intelligent are other animals?

(06:44):
This is always a great subject and something we've revisited
quite a few times on the podcast before. One time
we talked with friends devol here on the podcast in
an interview about his book. His book, I remember it
had a kind of awkward title. It was something it
was something like, are we smart enough to know how
marred animals are? Doesn't really roll off the tongue, but
it's actually a really good book. Uh. And and this

(07:05):
has come up with reference to the intelligence of birds
and and quite a few cases. Actually. Yeah. And so
this particular talk was loaded with interesting participants, But the
participant that got me thinking about brain soup was Susanna
or Kulana Uzel, PhD, a biologist and neuroscientists at Vanderbilt
University in Nashville, Tennessee, where she is Associate professor in

(07:26):
the Department of Psychology and biological sciences, and her research
focuses on what different brains are made off. Now, Robert,
I envy you getting to see a panel that involved her,
because I've actually watched a TED talk that she did
back from I think it was twenty She's a fantastic
public speaker. So yeah, she seems like a really good

(07:47):
public science communicator. Yeah, Like when I say, you know
that you have a panel of of leading scientists there
on the stage, like, don't don't imagine something stuffy, because
you often have some just really wonderful science communicators up
there that you know are experts in their field, but
are also able to talk about that in a way
that people at you know, various levels of expertise can

(08:09):
can jump in on. And that's certainly the case with
Susanna her colono ozel. Now, I do want to mention
you're you're hearing this last name. Sometimes you will hear
people pronounce it her colono hose l um. If you're
trying to look it up, it's h e r c
u l a n o dash h o u z
e l. Trying to to do the name justice here

(08:30):
with our bungling mouths. So, as she tells it her
Colona Hoose was working as a science educator um in
Rio de Janeiro, Brazil, and uh, and she kept running
into an old myth that I'm sure many of you
have run into before as well. Now, this is not
when we use the word myth too in the non
derogatory science. This is just foundational story, maybe involving supernatural elements. Yeah,

(08:56):
this is the derogatory myth. And that myth is we
only use ten percent of our brain. And this has
been used really overused in sci fi movies, especially over
the years, as recently as Teens Lucy and twenty eleven
is limitless um, which by the way, decided to double it,

(09:16):
but still but still stuck to this idea that there's
only a small percentage of the human brain that is available. Uh.
And of course all these these you know, films and
pretty much anytime you see this trouted out, it's it's
with the idea like there's there are ways to open
up the rest of the brain. There's like this dormant brain. Uh,
these dormant brain portions that can be utilized if only

(09:36):
you have the key. And the key of course is
right and it's supplied by you know, some sort of
mad science. If you're in a fiction or if you're
encountering it saying some sort of self help scenario, then
they're going to sell you the key or yeah, if
you're encountering it and uh, it's say nutritional supplement marketing.
I mean, this is a big thing out there. Yeah,
but we say it's a myth because and we'll break

(09:57):
this down a little bit here, but but basically, there's
nothing to these numbers. Now, we we all use of
our brains. Well, when you start, when you start to
look at the claim, it becomes less and less clear
what it even means. Does it mean we only use
ten percent of our brain at a time? Do we
only use ten percent of it ever in our whole lives?

(10:18):
Like what even counts as quote using the brain in
the first place. Yeah, I feel like we've talked about
about neuroscience on the show enough, you know, and talking
about various f M R eyes studies and like what
parts of the brain are lighting up, what parts of
the brain, and what networks of the brain are associated
with different thoughts and behaviors, etcetera. That it's it's clear

(10:40):
that like there's there is definitely a lot of stuff
in play and then virtually and then really everything is
in play. Um I guess, I guess the confusion could
be if you're looking at various images of fm R
E s and you're thinking, oh, well, that looks about
like ten percent. That looks about like ten percent. That's
a really good point. When people talk about f m
r I studies, sometimes they will loosely and casually try

(11:01):
to explain the findings of an fMRI I study by saying, Hey,
when somebody was doing this task with their brain, you know,
they were trying to tie a knot or they were
you know, whittling a whittling a horsey out of soap.
When they're doing this task, this part of their brain
lights up. That's the phrase this lights up, which implies
that the entire rest of the brain is dark until
it just lights up, as if it's like totally dormant,

(11:23):
and that's not true. I mean brain imaging studies like
you know, PET scans and fMRI I that they show
relative activity, so that they're charting activity and seeing what
areas get get surges of activity relative to what they
were doing at other times. Right there, the areas that
are not lit up are not lifeless, right, But I mean,

(11:44):
even back to this, I want to know again what
what would actually mean to use your whole brain or
to use certain percentages of your brain. I was reading
around about this and I found one pretty interesting thing.
So the neuroscientist Gabrielle and Torrey I think she's at
Boston University now. She wrote an interesting post about this
myth that I found on a website called Knowing Neurons,

(12:07):
and in one section of her article, she discusses difficulties
determining what it would actually mean to use quote a
hundred percent of your brain, Like there's no single way
to measure what portion of the brain is being used
at any given time. The default mode network, of course,
is in operation throughout the brain pretty much all the time.
But does that not count as the brain being used?

(12:29):
I mean, even when you're at rest, the default mode
network is whirrying away all throughout the brain quite unfortunately
in some cases. In some case, I don't know if
you'd want to be without your default Well now I
wouldn't want to give it up, but it it is
kind of thorn in my side at times. Oh, it
certainly can be. But then interesting I really like this part.
So she tries to take this claim seriously, like this

(12:49):
ten percent of the brain is being used claim, and
she's like, what would that actually mean? Well, she offers
one interpretation of what it would mean to use a
hundred percent of your brain, and it would mean a
Grand Moll seizure. So it would be like limitless except
Bradley Cooper takes a magic pill and it just makes
his brain like like we almost explode. Yeah, exactly. So,

(13:11):
to read from tories where quote, seizures are defined by
excessive and synchronous neural activity. If we wanted to use
a hundred percent of our brains to stimulate each of
the brains one hundred billion neurons, this is funny. We
should come back to this in a second, to maximum
capacity firing would result in a likely fatal physical experience
to hope for synchronous exit. Tory activity across the cortex

(13:34):
is in many ways synonymous to a Grand Mall seizure. Uh.
This is the most severe type of seizure and leads
to loss of consciousness and severe muscle contractions, not the
unlocking of superhuman abilities. So I think, obviously we don't
just want universal synchronous patterns of excitation of every neuron
in the cortex. That's stupid. That's not something to wish for, right,

(13:56):
It's like, you don't want the brain working that hard universally.
It's like you don't want your your you don't want
your xbox to be clearly just just heating up and
like that the fan is about to explode like that.
You know, something's wrong with it. Yeah, my CPU is
a constantly And she also mentions the default mode network.
You know, it's this diffuse, interconnected set of activity notes

(14:20):
that show activation when the brain is otherwise at rest.
You know, it shows the brain is pretty much never dormant.
There's activity throughout most of the brain most of the time.
So where did this clearly false claim come from? The
answer actually isn't known for sure, but I found one
commonly cited early example is a quote falsely attributed to

(14:41):
the American psychologist William James, the author of a great
classic text, The Varieties of Religious Experience, which is still
interesting to read parts of today. Yeah, we've cited him
a few different times on the show. Yeah, but apparently
James did write something generically kind of like this, but
without a number sited uh in a piece called The
Energies of Men, where you wrote, quote, we are making

(15:02):
use of only a small part of our possible mental
and physical resources, which is a very different kind of statement. Right. Yeah,
he's not putting a fine number on it or saying
like I mean that that statement alone is not not
implying that the portions of the brain are inactive, just that,
for you know, we're not taking full um advantage of
our neurological potential. And I want to mention a bit

(15:25):
more about that in a second. Uh So, as to
the origin of the phrase, the ten percent figure is
also cited in the nineteen thirties, and this has been
pointed out by quite a few investigators by the author
of an introduction to Dale Carnegie's classic self help book
How to Win Friends and Influence People, which possibly little
known fact Charles Manson's favorite book, Really Yeah, a classic

(15:47):
of business leaders and serial killers alike. But this explains
it a bit though. Right we have here an introduction
to a widely read popular book. Yeah, and the author
of the introduction says, we only act, you know, we
only use ten percent of our brains. The vast amount
of our mental potential is untapped. And I mentioned this
a minute ago, but I I just want to hammer
home again. I feel like I've seen this nonsensical ten

(16:10):
percent fact invoked by people selling some of the various
like brain booster pills and supposed new tropics supplements. Uh.
I would advise people to be cautious about that kind
of stuff. And I'm not ruling out the possibility that
there are some nutritional supplements or drugs that might in
some cases have a small effect on mental performance. But

(16:31):
if somebody is trying to sell you pills that will
unlock the untapped godlike potential of the you know, the
paid access part of your brain, the brains premium content.
As a general rule, be suspicious of this. I would.
I would advise in general, don't trust them and don't
give them your money, because they're certainly tapping into something
I think we all know to be true and we

(16:51):
all certainly want to be true, the idea that there
is room for improvement exactly, that we can learn new things,
that we can we can take on new pattern and
all of these things are true. You don't need a
phony number to back that up exactly right. I mean,
I think a large part of the basis for this
false fact about ten percent lies not in how much
of our brains we use as a as a ratio,

(17:12):
but in the way that we use our brains. And
the most salient example that comes to my mind is
the psychologist Daniel Konomon is really useful metaphors of system
one versus system to thinking. You know, so system one
we've discussed on the podcast before, but system one is
a suite of human brain functions that allow us to
process information in a fast, easy, automatic, and approximate way.

(17:36):
It's intuition, so you know, think rules of thumb, stereotypes,
intuitive and reactive thinking eyebawling it. Meanwhile, system two is
described as the slow, deliberate, effortful thinking, the kind of
reasoning you use when you make a list of pros
and cons, or you solve a math problem, or you
carefully plan a route of movement somewhere, or you effortfully

(17:59):
trace out the logic of an argument. We're all capable
of both kinds of thinking, but we also rely on
system one most of the time for most things, and
that's because of efficiency. Like, you can't process all information
in a slow, effortful way, you don't have time, and
System one is not all bad in some tasks. I
think it might actually be superior. Like consider the way

(18:21):
that overthinking some athletic tasks like shooting a basketball actually
makes you worse at them. You know, like a lot
of players find that they sink more baskets if they
just try to relax and let the shot happen rather
than focusing on the distance and the angle and everything.
And I think this actually even comes through in some
more abstract tasks, like sometimes I think people can be

(18:43):
better writers if they if they just kind of enter
a flow state and not sitting overthink over, deliberative lee
about the sentences they're constructing. This is very interesting and
hopefully this won't be too much of a tangent here,
but um, but it's also we have to be careful
about thinking about like system on a system to being
just complete like jackal and hides. Because actually the World

(19:05):
Science Festival, another panel I attendant had to do with
risky behavior and risk taking, especially in extreme sports UH
such as say free solo climbing UH and like free
cloaks of solo climbing is a great example because you
have you have certain individuals who definitely display more of
a system to approach, like they are methodical. They're they're
not they're not climbing at climbing that that that that

(19:29):
that sheer cliff without the aid of ropes, you know,
without having practiced it many times, without having climbed it
many times with ropes and thinking through several moves ahead,
you'll see where you're going to go. On the other hand,
you have individuals who do have more of an impulsive
approach to risky behaviors, risk taking activities. But like with

(19:50):
the basketball, you can say, well you can perhaps you're
engaging in system too to practice so that you can
reach the point where you can engage with the challenge
with a system one mindset. I think that's exactly right. So, yeah,
system one is not necessarily bad. It's not all bad.
Sometimes it's bad. And I think we're all aware of
cases where we have used fast, intuitive, reactive, likely inaccurate

(20:16):
thinking when we know that we probably could have and
should have stopped to think things out slowly and deliberately.
Like you can probably immediately think of examples where you
really wish you had switched over to system to thinking,
but you made a fast intuitive decision and you came
to regret it. And I think it's this kind of
frequently squandered mental potential that becomes the nugget of truth

(20:39):
in the ten percent factoid. We use our whole brains,
but we don't always use our brains as effectively as
we know we're capable of in every scenario, because it's hard,
because we're in a hurry. Does that make sense? Absolutely? Yeah.
We we we delive life. We have to engage both approaches
to our decision. Make yeah. All right. On that note,
we're going to take a quick break, but when we

(20:59):
come we're going to return to the idea of brain
soup and to the work of Susanna or Coolana Ozel.
Thank alright, we're back. So we got sidetracked on the
the idea of whether or not people actually use more
than ten percent of their brains. We do in pretty
much any way you interpret that. But that came up

(21:19):
because it was the basis of a journey of research
that the neuroscientist Susanna or ku Lana Uzel went on.
And so let's pick back up with her story from
the event you saw in New York City. All right,
So she was talking about another number that she kept
coming across that she found curious, that she found suspicious,
and that is the number one billion. Oh now, this

(21:41):
just came up a minute ago when we were talking
about an approximation. Now I don't want to indict the
author that cited and because it's a reasonable approximation, but well, yeah,
and we'll get into we'll get into that. But but yeah,
she kept running across this idea that the human brain
contains a hundred billion neurons and ten times as many
glial cells. But the thing is unlike that ten percent

(22:02):
of the brain thing. This was not merely the domain
of pop culture and science fiction. No, this figure freak
was frequently cited by neuroscientists, by psychologists, and and sometimes
applied as a as a comparison to the number of
stars in the Milky Way. I imagine a number of
you have heard this one before. What a hundred billion
stars in the Milky Way. Yeah, So the idea of

(22:22):
being like, hey, you have a hundred a hundred billion
eurons in your head. That's as many stars as there
are in the Milky Way, which I mean, on one level,
I think that's a useful metaphor because you're basically making
the statement that um that that inner space is as
complex and vast as we take outer space to be.
But on the other hand, when you start looking at
those actual numbers, uh, there's some problems on both sides

(22:45):
because for starters, the hundred billion star estimate in the
Milky Way is not a solid number. By some estimations,
the Milky Way has the mass of a hundred billion
solar masses, but other estimates, say four hundred billion or
even seven hundred billion solar masses is more accurate. Yeah,
this is a fascinating question on its own. So it's
difficult to know the number of stars in the Milky

(23:06):
Way galaxy because obviously we can't just count them, as
you can't look up there and count them. The best
we can do is estimate on the basis of the
mass and luminosity of the galaxy as a whole. But
this presents difficulties too because there are plenty of things
in the galaxy other than stars. Right, the vast majority
of the mass of our galaxy is not even normal matter.

(23:27):
It seems to be dark matter, which is still an
unsolved mystery and astrophysics and dark matter, of course is
this hypothetical stuff that we detect by measuring its mass,
in other words, the gravitational effect it has on stuff
around it, but it doesn't appear to interact with electromagnetic
radiation like light, making it unlike any other ordinary matter

(23:48):
that we know of. So at this point we don't
know what that stuff is. And that's most of the
mass out there. And then past that, we know that
a lot of the ordinary matter in the galaxy is
not just stars. Some of it is uh like unincorporated debris,
cosmic gas and dust, just hydrogen clouds out there. Of
course that's not the majority of the luminous matter, but
it's enough to complicate the problem of estimating star counts.

(24:11):
And then on top of that, you've got ice and
comets and planets and black holes and a supermassive black
hole at the center of the galaxy. And on top
of that also stars are of dramatically different masses, so
you have to figure out the right average stellar mass
to divide by. So it's it's almost like this isn't
a perfect metaphor, but I was trying to think of one.

(24:31):
It's almost like catching an unknown species of fish and
then weighing it and then trying to guess how many
bones it has. You know, like, you can't count them
just from looking from the outside. Uh. And the bones
aren't all the same size and weight. Uh. And there's
a lot of other stuff in there too that's not bones.
But so you can't sort of estimate based on a

(24:52):
number of likely assumptions, but you can't get an accurate count,
which leads us back to the human brain. And this
idea of this number that was thrown around again not
non in science fiction films, but in pure viewed papers,
in uh in in in textbooks as well. It was
just out there and sort of the the scientific zeite
guys the idea that there were a hundred billion neurons

(25:14):
in the human brain. And we didn't know where this
number comes from, right, And so Susannah Rocolano Hozel she
was wondering too, and so she she started looking into it,
and she looked and looked, and she found no pre
existing count, no scientific basis for the number at all.
The number was just floating around in the scientific world.
So the obvious solution is, well, somebody's got to to

(25:36):
look it up. Somebody's got to count these neurons, and
so she set out to do just that via a
novel tool that she developed in the lab in two
thousand five, and that is turning brains into soup, the
cification of the of of of the animal brain question.
Did she say what the soup tastes like? No? I

(25:58):
believe she said that the soup looked like unfiltered apple juice,
and apparently turned some of the students off of apple juice.
Perhaps forever it looks I mean, I've seen it looks
like murky swamp water. Yeah, so I doubt that anybody
tasted it, because this is sort of like priceless research material.
But uh, I don't know. Then again, you wonder if

(26:18):
somebody got curious at some point. I don't know. She's
she's a she's a pretty good she's a wonderful communicator,
and she has a wonderful sense of humor. I imagine
if somebody had tasted it, even accidentally, she would she
would have mentioned it in one of the talks or
or write ups or interviews that we looked at. You
know what, I've got a guess as to what it
tastes like. I bet it tastes like chicken stock. Probably

(26:40):
probably a good a good guess and well and perhaps
from Mount hot but we'll get into that. Uh So, basically, yeah,
so she she set out to make brains into soup.
Uh So, Basically she came across previous lab efforts from
the nineteen seventies to turn the brain into soups to
measure DNA concentrations um. And one of the keys here

(27:00):
is that soup is a homogeneous solution. So if you
reduce something like like the brain that to soup, then
you you have a better ability to like get a
sample of that soup, do account within that sample, and
then apply that, you know, to the full volume of
the soup. So anyway, she said, well, well I could

(27:21):
use this method then, uh to figure out how many
neurons during the brain. You know, liquefy cell membranes leave
the nuclei intact, allowing them, allowing everyone to you know,
to count the remaining nuclei in a small sample and
then multiply the number by the overall volume to get
the whole brain total of neurons. This is great. You
can't do this with a galaxy, can you, Like, you

(27:41):
can't just look at one section of a galaxy and say, okay,
now multiply that by the total area of the galaxy.
Because galaxies are not homogeneous, you would have to turn
it to soup first, which you cannot do or I
mean not on our scale. Anyway, you would have to
have godlike powers, and then you would destroy the universe.
Maybe that's how the world ends. That's the true Naroc scenario.

(28:01):
Is the god or gods asked the question how many planets?
How many stars are kicking around this thing? Well, let's
turn it to soup and find out exactly, Loki says,
or you can't count the number of stars in the sky,
and he's like, watch me, Well this sounds this is
exactly the kind of gamble that that ancient gods would
get into. You know, um, just a mere bet, and

(28:21):
everything for mortals is at stake, right, But anyway, or
Colono was not interested in that. She's interested in the brain.
So the main challenge with souping the brain was souping
it just enough to retain the cell nuclei, but without
breaking any of that down. Initial souping experiments via essentially
a detergent went too far and attempts to flash freeze

(28:43):
them with wicked night liquid nitrogen and then blend them. Well,
that just caused a cracked mess. And she says that
they were like frozen pieces of brain all over the place.
I think if anyone was going to taste her brain soup,
that was probably gonna be when it would have occurred.
But anyway, then she found a solution fixing the brain
tissue with from all the eyed before the dissolving it.
And the result, she says, again, looks like unfiltered apple

(29:05):
juice and allows this kind of count to take place. Right, so,
you can pull out a small sample, you know what
the volume of that is compared to the entire volume
of the sample, and then you count the number of
neuron nuclei in the small sample and then multiply that
by the total volume exactly. Okay, So I think I
mentioned earlier there's a TED talk she did in where

(29:26):
she shows off anyway, in the middle of this this
TED talk, she shows off a vial of this brain
soup on the stage. It's a little glass jar of
mouse brain souper. Might be plastic, I don't know. It's
a jar of mouse brain soup. It looks like murky
swamp water. It's kind of sort of like an off
beige kind of color. One of the best things about
this particular talk, though, is that when she shows off

(29:47):
the jar, she doesn't go and pick it up from
a table or demonstration stand or something. She's just got
it tucked into the back of her belt like a gun.
She just pulls it out, and then when she's done
show in it off, she just slips it right back
in under the belt. I mean, I guess it must
have been there all day. Uh well, you know, one
of the things that she pointed out in the talk

(30:08):
is that some when she started doing these experiments, some
uh people objected. They were like, what are you doing
through these precious brains? As if she were wasting brains,
as if she were essentially the dan ackroid character from
it came from Hollywood, just you know, massacuring brain material.
But she pointed out that, you know, the aside from
it being highly useful, as they will explore the rest

(30:29):
of this episode, also they freeze it and so they
can save it for later. She says, she has a
whole database. The freezer is full of brain soup. I'm
sure all properly labeled and dated. Yes, So what they
did is yeah, they apply to fluorescent stain to differentiate
the neurons from other cells. And she started with rats
and other rodents, eventually working up to human brains, and

(30:52):
eventually she had a verified count not one billion neurons,
but eighties six billion neurons. Apparently this can be higher,
as high as they ninety one billion, for instance, but
eighty six billion is the like the ballpark count. That's uh, well,
that that doesn't seem too far off. I mean that
seems within a rough order of magnitude level of reasonableness.

(31:13):
Well it does, and it doesn't like you know, she
points out that this may not may not sound like
much of a difference to a lot of us. And
I have to admit, when I first heard it it,
I didn't really register that it was that much different
thundered billion versus six So it sounds like, all right, well,
we almost got it right. And uh, the thing is,
you know, she says that ten billion neurons is really

(31:35):
is not a small sum when it comes to neural change,
and when we're talking about the evolution of of of brains,
she says, the difference there is an entire baboon brain
and chain. So so yeah, that's a lot of neural
power we're talking about there, and to be off uh
on that can you know, can have consequences as well,

(31:56):
explore when we're talking about like what makes the human
brain seemingly special? Yeah, that that's interesting, I mean, and
that's where it ties into her larger theory about what
it is that's special about human brains. So obviously, neuro
anatomists and other scientists have long debated this question what
makes human brains unique? Why? Why are we the only
ones with computers? You know? Why don't rabbits have computers

(32:19):
and all that? Uh? And so what is the physical
property that gives the human brain its power? Is its size?
I mean, that clearly doesn't make any sense because sperm
whales have brains that there are something like, I think
at least six or seven times larger than human brains,
and yet they don't seem to be smarter than us. Likewise,
the elephant brain is much bigger and exactly, and we're

(32:40):
not discounting the intelligence of whales and elephants, but but
but clearly their their neural power is not on the
same scale as as human power, and we have to
ask the question why, right, So we're able to do
things that they're not able to do. And is that
difference related to sheer size of the brain? Clearly not
could it be? And another thing that's often put forward

(33:01):
is the ratio of brain size to body size, right. Uh,
the encephialization quotation that actually doesn't seem to quite cover
it either. Right. So one of the things you pointed
out here is that we'll just consider a couple of
these neuron counts again, humans eighty six billion neurons. Uh.
And then we have something like like a rat two

(33:21):
hundred million neurons uh. And a goody which is a
South American like rather plump kind of critter, but it
is a rodent eight hundred fifty seven million neurons. Al
Monkeys have a one thousand, four hundred sixty eight million neurons,
while a cappy bara again a rodent one thousand, six
hundred million neurons. Okay, so they're up into the billion range,

(33:43):
but the difference here is still orders of magnitude of difference, right.
And and her argument is like when you compare like
like sized rodents and primates the primate brains, uh, you know,
maybe the same size, but there are more neurons in
the more advanced primate brains. Right, So what seems to
be going on here is that it's not so much

(34:03):
that there's something really special about human brains, but there's
something special about primate brains. Primate, the brains of monkeys
and apes, you know, the primate creatures like us, that
they have these densely packed, neuron heavy cortex cortices. Yeah,
and then it comes down to concentration of neurons. And
by the way, she also has found that birds have

(34:25):
primate like concentrations in the forebrain, which lines up with
the with their intelligence despite much smaller brains than other
intelligent animals. Yeah, we mentioned this before, but this really
comes through in the sometimes startling intelligence of birds like
Corvid's and parrots. Yeah. You look at a parrot, like,
how big is it's brain? Right, It's like, you know,
you you snack on nuts larger than this creature's brain,

(34:48):
and yet it has this startling intelligence about the efficiently
packed to the neuron crammed forebrain, sort of like a primate. Yeah. Yeah. Meanwhile,
whale brain, you could climb inside of it, and it's
and and it's it's it's not quite there. All right.
On that note, we're gonna take a quick break, and
when we come back, we're gonna explore more of Susanna
or Colono Ozell's ideas about the human brain, how it

(35:11):
has evolved and whine has so many neurons. Thank you,
thank you. All Right, we're back, so more about brains, alright.
So one of the big take aways from Susanna Orcolano
Ozell's work is that, of course, a big brain doesn't
necessarily mean high levels of cognition. Again, it's more about

(35:32):
the neuron concentration. Yeah, this is what we were just
talking about with the fact that obviously, you know, like whales, elephants,
all these have much bigger brains than us. But there's
a lot that our brains seem able to do that
those brains can't. So it's not just size. There does
seem to be something special about the way that primate
brains are organized. And that's the thing, primate brains, not

(35:55):
not just human brains, because that's something that Arcolano Ozel
really drives home, is that the human brain is just
a scaled up primate brain. There's nothing special about the
human brain beyond that, nothing God touched or anything of
the sort. She says that this is very much in
line with what Darwin thought and was criticized for. Darwin

(36:17):
thought the human brain was just another primate brain, but
those who came after him, they often took their evolution
with a hefty dose of human exceptionalism. Wanting to think
about us is a special case that the rules of
life don't apply to like they apply to every other
animal on Earth. Right and likewise, um l Ozell says
that she faced resistance to her results due to the

(36:38):
fact that they didn't support this view of human brain
exceptionalism versus the brains of other primates. Again, it's just
a scaled up a scaled up primate brain, right, So
her idea, what she argues, is that what the human
brain is. You start with a primate brain, which primate brains,
like brains of monkeys and apes in general, are more

(36:58):
crammed with neurons other types of brains in the animal
kingdom usually, and then you look at all the primates
and humans have by far the biggest primate brain. And
then because it's the biggest version of this densely packed
primate neuron housing center, we are the smartest. That's essentially
what makes us the smartest. And we'll get into why
this seems to be the case and why um the

(37:21):
the argument that Susanna rocol Hosel makes for it as well. Uh,
but before we do that, I want to I want
to touch base in another area that she lines up
with all of this, and that is the subject of
longevity in warm blooded vertebrates anyway, UM, because it seems
to be the case that neurons are more important than
body size here as well. So in two thousand eighteen

(37:43):
research that was published in the Journal of Comparative Neurology, UM,
Rocolino Ozel and co authors found that in primates, birds,
and other warm blooded creatures, the number of neurons that
you have in the core in the cortex of a
species predicts about seventy five sent of all the variation
in the longevity across species. Body size and metabolism the

(38:06):
usual standard because usually that's what we think of, right,
an elephant lives a while, it's big, whales of a
while big, right, She says that this only predicts around
twenty of of of the cases of longevity. And here's
another slice of human non exceptionalism. If you do the math.
She says, this means that humans live about as long

(38:26):
as you expect based on their neuron load. In this
particular brain soup study examined more than seven hundred warm
blooded animal species. I want to see a list of
those soups flavors. Yes, the super menu is. It's quite
extensive at her lap. Now, why is there a connection
between neurons and the cerebral cortex and longevity. Well, she

(38:48):
says more work is required to figure this out, but
she does have some ideas. And here's what she said
in a press release on the paper from quote. The
data suggests the warm blooded species accumulate damages at the
same eight as they age. But what curtails life are
damages to the cerebral cortex, not the rest of the body.
The more cortical neurons you have, the longer you will
still have enough to keep your body functional. The cortex

(39:11):
is the part of your brain that is capable of
making our behavior complex and flexible. Yes, but that extends
well beyond cognition and doing mental math and logic reasoning.
The cerebrial cortex also gives your body adaptability as it
adjusts and learns how to react to stresses and predicts them.
That includes keeping your physiological functions running smoothly and making
sure your heart rate, your respiratory rate, and your metabolism

(39:34):
are on track with what you're doing and how you feel, uh,
and with what you expect to happen next. And that
apparently is a key factor that impacts longevity. Fascinating. Yeah,
so I love how already just this this concept of
of brain, not this concept of brain soup, but this
tool of making brain soup. It already you know, is

(39:54):
turning certain things that uh, we used to think we
knew about brains and the human rain and how it's
different from other animals and indeed how how other animals think,
turning all of that on its head and change us
another way of thinking about it. Yeah. So one thing
that this would, obviously, I think have somebody wondering about, is, Okay,
if if humans are the upper end of the primate brain,

(40:17):
you know, with your neuronal loads, you've got a lot
of neurons in the human human brain, how did we
get that way? Does it happen? Because again, we can't
go with any mythic interpretation here, whether there's no ancient
alien or gods scenario where where this particular primate was
was touched and made special. No, we need to look
to something in the natural world, something that that that

(40:40):
explains this, like rapid growth of the brain and uh Erculano.
Uzel's hypothesis has to do with straightforward energy economy, the
energy that different species are able to take into their bodies. Right.
She says that she thinks it all comes down to
the calories a mass via a very early technological development

(41:00):
that our ancestors made, that being cooking. Now, this is
an interesting hypothesis. I like this. Yeah, we know, we've
discussed the essential role that cooking played in human advancement before,
how it externalized. Digestion allowed you to uh sort of
to you know, heat up this pod or not even
necessarily a pod, just you know, a pit with fire

(41:21):
even and partially digest various organic matter before you give
your own digestions a digestive system a shot at it.
This makes it easier to digest. You know a lot
of foods that would be impossible or difficult to consume otherwise,
either because of their chemical components, or maybe they're just

(41:42):
tough they're hard to chew, or or or they can't
be chewed, and cooking can make them softer, and of
course just speed up overall digestion. Yeah, it just gives
your digestive system much more access to the nutrients inside
through a variety of means. Yeah. Because and this ties
into neurons, because neurons require energy, a lot of energy actually, Yeah.

(42:02):
And the more neurons you have, and the more energy
you require to charge them up. Like your brain consumes
energy at a rate that is not proportional to its
size relative to the rest of your body. It is
the the great energy hog of your body. Yeah, we're talking.
Neurons require six kilo calories per billion neurons per day,

(42:24):
so um urkilno Ozell points out that the human brain
costs on average five kilo calories per day, so, in
her words, not quite a whole hamburger. But but I mean,
when you think about that in terms of food, the
types of calories you can acquire in the wild, without grains,
without access to easy meat and all that, that that's

(42:47):
that's a tough requirement. Yeah, let's take a moment to
just realize how how, how how amazing the hamburger is.
I mean, and just in terms of like how much
uh you know, protein and potential new atrition is just
jammed into that thing. There's a lot of energy in
the hamburger, like it or not. And we, you know,
we take for granted, you know what a robust chunk

(43:08):
of energy that is. And if we had and if
we had we didn't have the hamburger and of course
all the things that are comparable to the hamburger and
modern culinary tradition, and if we didn't have that to
to eat, if we had to eat like our primate
brethren did and still do without cooking and modern food. Uh.
She points out that we'd have to spend nine point
five hours every day eating so instead of so you're

(43:31):
just eating like raw vegetable matter most all that you
like a lot of animals do in the world. If you,
if you like, like we do, watch a lot of documentaries,
you'll frequently encounter, uh, you know, some an animal or
another of panda and you're like, oh, all it does
is eat because it has to. It has to eat
all the time, you know, to maintain um uh, this

(43:52):
this body and ultimately it's brain as well. But of
course our brain again has tremendous energy requirements. It only
makes up two percent of our body, but it requires
twenty five of the body's energy, so that five calorie
burger is just part of a two thousand calorie per
day diet. So Kolona Ozel contends that without cooking, we'd

(44:12):
be in the same state we'd evolved to one point
five million years ago. We'd be small primates with essentially
the brain power of a modern guerrilla, but with some
stone tool making abilities. This is kind of encouraging as
a as a hypothesis for people who love cooking kitchen
culinary enthusiasts, You you may well be taking part in

(44:33):
the most crucially human of all activities. Yeah, and I
believe Michael Pollen has made a very very similar argument
before in terms of like why we we we love
cooking and why even if we don't cook, we're drawn
to the myriad cooking shows that are out there. You know,
we want to watch somebody cook, we want to learn
about about different culinaries, traditions, and even for my own part,

(44:54):
I've never been much of a chef. I am not
much of a chef either, but I've been enjoying some
of these various like meal box things recently, and it's
teaching me some of the basics of cooking. And you know,
I'll still curse at a tomato, but there's something fulfilling
about going through all the instructions and and turning this

(45:15):
sack of raw materials into a delicious meal. Well, uh,
tomatoes are tricky devils that can be seriously, I they're
They're at both ends of my you know, food love
and hate spectrum. Basically, my favorite food in the entire
world is a really good ripe summer tomato, and my

(45:37):
least favorite food in the entire world is like a
mealy white winter tomato. It's the worst thing on earth. Yeah,
it's there's It's kind of I feel a similar way
with cantalope, Like there are a lot of mediocre cantlelopes
out there, and if you have one, you could easily
turn your back on cantal loops forever. But when you
have like a really good cantlelope, there's nothing else that
can beat it. Well, it's funny we talked about these

(45:58):
extremes with agriculturally produced fruits and vegetables. Arklanzel points out
in Somewhere I was reading or one of her talks
I think where she says, you know, it's kind of
funny that the inherent logic of of what she's showing
here is even there in some of the diet trends,
where like what do people do when they want to
lose weight? Well, one popular thing is the raw food diet,

(46:20):
because suddenly you're condemning yourself to a forging type existence
without you know, without the calorie benefits of cooked food. Yeah, exactly,
but but cook But cooking food is something we did
develop again, and that was roughly one point five million
years ago. Um, and this is the key technology, she says.
It changed what was possible energy wise for the evolving brain.

(46:42):
Our brains got big in a hurry after this, and
our food technology, of course, continued to evolve, most notably
via the agricultural revolution. Definitely. I mean that the history
of of of human civilization is the history of our
manipulation of food really and our stockpiling of food it
and then our trade of food in our wars for food.

(47:02):
So we are using research that makes use of the
brain soup technique to discover the possibility to discover how
important the invention of literal soup might have been. Yeah,
I love the cyclical nature of this particular episode. We
started with with the brain soup, and we came back

(47:24):
to brain soup. It's glorious, Okay. Introducing a new show segment,
Soup Facts, Facts Facts, with Joe McCornick. Here's something. If
you're ever trying to figure out how much to season
your soup. You know you don't want it to be
too salty, of course, but you also don't want to
underseason and how much salt should go in a soup.
The best way to figure that out is to get

(47:46):
the soup to the temperature that you plan to serve
it at, and then taste and see how much salt
it needs there. Because the amount of salt that we
can taste when we taste something for seasoning varies drastically
depending on what temperature the food it is at. So
you might you might taste it and it tastes like
it needs more salt, or it already has enough salt

(48:07):
at one temperature, but in a different temperature it might
taste totally different. Interesting. I hadn't thought about that. I
will use that the next time I'm I'm I'm following
instructions from a box and have to make soup all right.
Another place I always mess up with salt is with pasta.
If I'm boiling pasta, like I keep putting into little soup,
like I'm so afraid of oversalting something, well, then I'm

(48:30):
I'm and then my my wife will come in and say, oh,
then you're supposed to be throwing like a whole fistful
assault from there. Basically, it's a reasonable concern. I mean,
you can if you under salt something, you can always
add more. But if you over salt you can't take
it out right. Well, you know, I think back to
the cocktail scenario, like if I mix up, if I
mess up a cocktail to the point where I can't
fix it, um, then I've wasted like two drinks, you know.

(48:53):
But if I do that with a super stew and
I've ruined dinner, like I have to then go and
get a pizza or something, and I've way did all
of these resources. And you know, the most heartbreaking thing
you can do is have to potentially throw food away.
And I have I have got I have over salted
things in the past to that point, you know, where
it's just basically inedible. There was some recipe where I

(49:14):
had to. And this was like a box meal years
ago when I was first figuring it out, and I
had like a thing of salt and a thing of sugar,
and the sugar went into one component salting the other.
I flipped them, which made like a pretty sweet cole
slab that also just did whatever the other thing was
was just inedible. That's a sad story, all right, So
I guess we're gonna leave it there. Uh again Susannah

(49:37):
Roclinol wonderful science communicator. UH look her up. She's all
over the internet. You can find her ted talk readily easily,
and they're also various interviews with her. And then of
course the scientific papers are out there to look at
as well. Uh. So also thanks to the World Science
Festival UM for letting me attend and uh and you know,

(49:58):
taking in all this data. Look up the World Science
Festival as well. Uh. They have a wonderful YouTube page.
They'll put a lot of these talks up um, you know,
over the course of the weeks and months ahead moving
into next year. And in the meantime, if you want
to check out more episodes of Stuff to Blow your mind,
head on over to Stuff to Blow your mind dot com.
That's the mother ship, that's where you'll find them all.
And if you want to support our show, uh, we

(50:20):
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Huge thanks as always to our excellent audio producer, Tari Harrison.

(50:41):
If you would like to get in touch with us
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a topic or a guest for the future of the show,
or just to say hello, you can email us at
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(51:03):
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