Colossal: The Science of Human Height

From fictional obsessions with impossible giants to questions to height psychology and the upper and lower limits of human size, join Robert and Joe for a massive exploration of human height in this episode of the Stuff to Blow Your Mind podcast.

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:03):
Welcome to Stuff to Blow your Mind from how Stuffworks
dot com. Hey, welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick. Today
we're talking about human height. We're talking about the limits
of human height. We're talking about the giant humans start humans.

(00:25):
So it seemed like the most natural place to begin
this discussion is, of course, with nineteen fifty seven's classic film.
Some of you may remember it from Mystery Science Theater
three thousands, some of you may have just experienced it
straight up, The Amazing Colossal Man. Now, Robert, I am
sitting here looking at this looping gift that you put
in our outline of a gigantic dude who seems to

(00:47):
be filmed with like rear projection to make him look
bigger than he is, throwing some sort of instrument that
seems hand sized for him, but he's impaling a tiny,
tiny person with it. Oh yeah, this is a great
scene because he's the character is is Glenn Manning, Lieutendant
Colonel Glenn Manning. There's an atomic blast, he ends up
growing uncontrollably. He loses all his hair and his clothes

(01:10):
except for you know, alloying the loth that I assume
is made out of sale made out of sale cloth
or something. And there's a scene where they they're trying
to arrest his growth by jabbing him with this giant
hypodermic needle. Of course looks like a giant hypodermic needle. Um.
So they come in, they jab him, and then he
picks the thing up, looks at it with anger, and

(01:32):
then just throws it down like a javelin and impales it. Dude.
It's a classic scene. So this was nine seven, and
this was this was part of the era of filmmaking
in America where it was just giant everything all the time.
Giant bugs, giant you know, leeches, giant rats, giant what else,
giant giant spiders of course, any of those grasshoppers praying Mann.

(01:54):
This is I mean, yeah, you name it. If it
looked good or if it just looked passable and giant form,
somebody was blowing that thing up. I think they'd figured
out how to do rear projection technology that looked okay
in film, uh, and so that they were like, oh god,
we can make anything look you know, hugely out of proportion.
Let's just exploit this to the max for fifteen years

(02:15):
and then throw it up on a drive in the
kids will come and see it. Yeah, And of course
the plot was always atomic radiation, right as it was
in this case. So in The Amazing Colossal Man, the
guy you said he gets uh irradiated by nuclear blast.
I think he actually he's like he's they're observing the
blast from the safety of a trench, but he gets
up out of the trench to rescue somebody or something

(02:36):
that it's just you know, it's an heroic act. But bam,
he gets blasted and it's a great scene of just
standing there at the with the radiation washing over him
and yeah, and he's reborn as this colossal being uh
and it begins messing with his mind too. Yeah. So
it's sort of similar to Beast of Yucca Flats. Same
thing happens to Tour Johnson, and that he gets hit

(02:57):
with an atomic blast and instead of vapor I sing
him burning him up. It just kind of makes him
look crazy, makes him look a little bit bigger, and
he has some oat meal on his face. Yeah. But
then but the thing is, I mean, I don't want
to undersell Tour as an actor, but Glenn Langan, who
plays Lieutenant Colonel Glenn Manning in the in the film
here like he brings. He brings a certain amount of

(03:18):
at times hammy but still legitimate humanity to this character
where you end up feeling for him like he's meeting
his his wife. Uh you know, he's he still has
his humanity about him. He's even as the condition begins
to go through his head. So you think this is
actually a pretty good B movie, right, Yeah, I mean,
going into it knowing what to expect out of a

(03:39):
B movie. I think this is a great movement B movie.
I think this is just a fabulous example of a
particularly of a bomb B movies directed by Oh yes,
the great Burt Eye Gordon bert I Gordon. So he's
actually still alive and yeah, I was looking him up
and yeah he was born in two. He's still kicking

(04:00):
at ninety two as of this recording, and IMDb claims
that he directed a film in Okay. So Burt Iye Gordon.
You you might have noticed his initials are b I
G This Uh this. He didn't, as far as I know,
he didn't change his name to be like this. It's
just a happy coincidence that Bert Eye Gordon was known

(04:20):
as Mr Big, Mr b I g because he loved
to make movies about things that grow bigger than they
usually can. Uh. So. Other movies of Burt Eye Gordon's
include War of the Colossal Beast that's the follow up,
and then there's The Spider or Earth Versus the Spider,
that has a larger than normal spider and it's not

(04:41):
just like a suitcase size spider, it's like a giant spider. Like,
I mean, you gotta go go big with your giant spider.
Like she lops size pretty much. And then there is
Village of the Giants. There's King Dinosaur, which has a
fun Mystery Science Theater episode in which astronauts travel to
a planet full of giant reptiles and then they sort
of flirt and romance each other. And then there's a

(05:02):
lizard that is supposed to be a t rex I think,
and then the astronauts nuke the planet to wipe out
indigenous life and make it safe for human colonization. Uh.
And then of course there's also the Beginning of the End,
another Mystery Science Theater episode, but that movie has a
Midwestern town threatened by giant grasshoppers again, atomic radiation. Yeah,
but since we're talking about human height primarily today, back

(05:25):
to the Amazing Colossal Man. Yeah, so nobody's gonna gonna
bring up The Amazing Colossal Man is like a perfect
example of science, but it does at least flirt with
some of these ideas because you have this this guy.
He's gigantic, he's powerful, and yet he seems to be
in a fair amount of just constant misery. Um, it's

(05:46):
been a little while since to actually have seen it,
but I I seem to recall that not only there
there's there's elements of it affecting his mind, but but
perhaps just being that big is at least a little
bit painful as well. Um, and the mind thing is interesting.
I have a feeling in the in the in the film,
it's more about like radiation or something affecting his mind,

(06:06):
making him a little crazy, a little hostile. But I
can't help but wonder it has something to do with
the blood flow to his head. Oh yeah, like you're
just trying to scale up the human body that things
aren't necessarily gonna work right. Yeah, Because as we'll discussed,
that's a major issue when you start thinking about gigantic
human bodies or gigantic bodies of any kind. Um. For

(06:27):
after after all, look at the draff right tallest vertebrate
on Earth. Uh And and it has to uh, you know,
sort of quite a bit of energy to pump blood
up to its brain. It has like an amazing amount
of hypertension. I mean, the same kind of hypertension that
would cause vascular damage to a human being and eventually
perhaps lead to uh, internal injury and death. Is just

(06:49):
normal for a draft because it's got to get all
the blood up the neck to the brain and then
when it lowers its head to drink gravity. You can't
have gravity then like sending all this blood to the
head and what may in the draft's head explode. Nobody
wants that, And that's why the giraffes have this system
known as the rete mirabel and that's Latin for wonderful
net uh. And it's just this net of arteries and

(07:11):
veins that diverts some of the blood flow, equalizing the
giraffe blood pressure when the animal lowers its head. That's beautiful. Yeah,
it's like a natural release valve to keep you from
living in a world full of exploding giraffes. But it's
an example how to have a creature that big, you
have to have additional engineering constraints thrown in there to

(07:31):
allow that creature to live on that scale. Yes, and
though The Amazing Colossal Men didn't get into a lot
of the details of the science of what it would
take to scale up a human body, other other writers
have sort of dealt with this, right, Um, yeah, you know,
I have not read a lot of the you know,
they guess as far as a literary trope, that the
giant humanoid is not really explored all that much. But

(07:55):
the late Heart writer Michael Shay, he explored this a
little bit in his novel uh Niff. One of his
niff the Lean Novel's Minds of the Bahina, which is
a fine, fine work of dark fantasy that I highly
recommend anyone out there looking for that sort of thing.
But he also wove a lot of science into his work.
And at one point in this book we encounter a
human who has grown to colossal size. But he's so

(08:15):
colossal that like he basically is just in constant pain.
He can't even sit up. He has to just crawl
into the ocean and float away just because the body,
the proportions of his body are not made to support
that kind of mass. Now, wasn't there an old theory?
I can't remember where I read this, but I remember
hearing there was some old theory that these the largest

(08:37):
of the dinosaurs, say like a brachiosaur or something like that,
could only exist by by standing around in water all
the time to partially support its weight with buoyancy. Yeah.
I've read some of those as well. In fact, we
have an article on how stuff Works dot Com that
I put together, like what's the largest land animal that
ever lived? And he's a part some of these issues
with the sauropods. But for to whatever extent that was

(09:00):
ever proposed as a theory, I don't think that is
believed today, right. And the other co course important thing.
You look at these most massive creatures, the most massive
land creatures living today, uh, are definitely walking around on
four legs. The Saara pods walked around on four legs.
So um, it's it's very difficult to imagine a bipedal
creature of that size. But then again, we have examples

(09:22):
like the Tarrannosaurus rex, a bipedal creature that is extremely large,
and they're actually there are larger bipedal dinosaurs than the
sarannosaurs rex. Yeah, not quite as big as the sauropods,
but certainly yeah. Okay, well, so we should look at
the issue of height and size in humans because obviously
you don't have to look any further than the science
fiction films of the fifties to see this general obsession

(09:45):
with the idea of things being bigger than normal humans
and other animals. But while we're captivated with height and
size in that kind of simple brutal part of our brains,
we also have this counter narrative running right where in
our literature and folklore there's always this story of the
smaller person defeating the larger person David and Goliath to

(10:05):
Jack and the bean Stalk, which you know, the folklora
says a variation on this very ancient story they called
the Boy who Stole the Ogre's Treasure. There are a
lot of variations of the story. And then in the
modern day we have, for example, Bruce Lee always beating
the bigger guy. Right, have seen a film where Bruce
Lee does not just beat everyone up. It's true to

(10:26):
the point of boredom, where it's like, really, these villains
don't have shot. They seem to know that the thing
you want to see most is this little guy, this
little Bruce Lee, just killing somebody who's much bigger than
him by punching him to death. And how would we
fit Master Blaster into the scenario? Ad Max taking a
Master Blaster who himself is a giant with a little

(10:47):
person on his shoulder. That seems to subvert the trope,
doesn't it. So anyway, we we've obviously got this obsession.
We're we're very into the idea of size as a
basic indicator about how we should judge other people. Uh,
and that sort of makes sense. I mean, it doesn't
make sense morally judging other people by their sides, but
it sort of makes a biological sense why we would

(11:09):
have these instincts. And and height is a sort of
basic biometric indicator. For example, it's useful for scientists to
track because it can be objectively measured, though not always
with perfect act accuracy, because you know your height varies
a little bit from different parts of the day, and
you know it's not going to be exactly the same
every time you measure it. But it's correlated with other

(11:30):
important facts like nutrition and health. Uh, and in humans,
height is, of course, on average, sexually dimorphic. We know this.
Average male height is usually a few inches taller than
average female height. One thing that I was really interested
in was I was wondering if there's any population of
humans on Earth where that's not the case, And I
couldn't find evidence of it, but I wonder if there

(11:51):
is one out there that would be kind of cool
to know. Would Yeah, it's just so so so far
just talking about human height, as we've discussed, you have
you have of the the the the inherent sexism in
the in the situation right, men on average or taller
and there and therefore we're putting this focus on on
height being an indicator of power. Um. Certainly, increased height

(12:17):
can conceivably be an advantage in various combat scenarios. Of course,
a lot of that depends. Most of that depends on
the skill of the fighters involved, and of course just linguistically, right,
even if you're in a profession where really the height
of an individual has no role at all, you'll still
hear people say like, oh, well he's a giant in
the industry, or oh she's a she's a looming figure

(12:39):
in her profession, or or you might hear someone put
down to say, oh, well that that was very small
of them to do that. Like what, what do all
those words even mean? You know, we're we're still populating
as if it's Game of Thrones and we're surrounded by
giants and dwarves and giant blooded people. Yeah, but even
if you are not, say, applying to be a pro
wrestler or something like that, there are jobs, such as,

(13:01):
for example, being a salesperson where somebody might hire you
based on height because they know that the the inherent
biases of the customers might favor somebody who's taller. So
one of the big scientific questions about human height would
obviously be what controls human height? It's a clear fact
of nature that we see obvious, you know, metric differences

(13:24):
in the height of different adult individuals. So where does
this difference come from? And I found according to a
two thousand six explainer I found in Scientific American by
molecular biologists Chow Kwing Lae and Gene Mayor of the U.
S Department of Agriculture Human Nutrition Research Center on Aging
at Tufts, twenty two percent of differences in human height

(13:46):
are controlled by environmental factors, and sixty to eighty percent
are controlled by genetics. So scientists have arrived at these
numbers through a number of different means, including things like
twin studies, you know, studying people who Okay, so we
have monozygotic twins here, they should have pretty much the
same genes, but can we see any variations in height

(14:08):
between them or between them and other siblings and sibling studies, Uh,
depending on what what environmental factors they're getting, such as nutrition,
especially nutrition and early childhood, early childhood health, access to healthcare,
and things like that. And from this that they've discovered
that the rate of influence of genes and environmental factors

(14:29):
is variable, but it's variable around these basic ranges. But
one thing that is true is that on average, humans
today are significantly taller than they were a few hundred
years ago. Have you ever noticed this, like if you,
I mean, it's clear if you just look at environments
and appliances designed for people a long time ago. There

(14:53):
are lower ceilings, lower doorways, smaller beds, smaller pieces of
clothing such of armor was one I believe you mentioned earlier. Yeah,
and so I though, that's an interesting one because I
was looking into that and then I couldn't. I have
this impression that I've seen suits of armor that appear
kind of small compared to what I would think of

(15:14):
as a you know, a large warrior today. But I
was looking for evidence of this online and I couldn't
really find anything as saying that suits of armor are
smaller than we would expect them to be. So it
made me wonder if suits of armor being made for
the nobility and military classes of previous eras may actually
have been larger than would have been required for the

(15:36):
regular people, because, as we've discussed in previous episodes, we
have these examples of noble individuals, ruling class individuals from
hundreds and hundreds of years ago who still were tremendously
hot at tall even by today's standards. Oh yeah, I
remember Old krogan Man, Old krogan Man, the bog body.
What was he like six four or six six? He

(15:57):
was incredibly tall, um, And of course history is full
of these stories. Sometimes, I mean a lot of times
you have to take him with a grain of salt, right,
because there's a ruler and he was really tall. Do
I believe you, was he really really taller? He was
he just he's just always standing on something or is
this just you know, the myth and the legend of
the man like one that always comes to my mind.

(16:18):
And this is I think in large part because my
my dad would tell me stories like this is a
kid but um uh in ten sixty six, the events
of ten sixty six Battle Hastings and all that. You've
got stories of ten sixty six when you were a kid. Yeah,
my dad would tell me about all that. That's pretty cool.
Of course, you had, you know, three different forces vying

(16:39):
for control. There. You had Harold Godwinson, uh, king of England,
who had William the Conqueror coming up from from the continent.
And then of course you had Harold Hadrada, the King
of Norway, and he was according to many accounts here,
he was taller than most men. And Harold Godwinson makes
equip that he is going to uh, he's going to

(17:01):
offer him something, and he's gonna offer him six feet
of English soil or perhaps more. Sometimes it is say
perhaps seven feet of English soil, since he's taller than
most men. Um. The idea that he's going to you know,
gift him the grave here but but yeah, here, here's
a giant. Uh in history to what extend was an
actual giant? I'm not sure, but but certainly we have

(17:23):
tales like this of of and in some cases skeletal
evidence of tall noble individuals. And yet we have evidence
that the average person of of a hundred and fifty
years ago or earlier maybe you know, even going back
longer than that, was just not as tall as the
average person from the same ethnic groups and societies are today.

(17:44):
And so why are people taller today? You know? One
of the obvious questions is has height been selected for
as a gene? Has there been evolution? Are we evolving taller?
And I would postulate we can get into why in
a moment. I don't think that seems to be the cause.
It doesn't look like it. I think scientists think that
the change in human height is more due to environmental

(18:07):
factors that I was talking about earlier, rather than major
changes in the genetic factors controlling height. And this would
make sense given what we know about improved access to
healthcare and nutrition around the world. Right, Yeah, A lot
of the a lot of material that I was looking
at for this was definitely focusing in on England and
looking at industrial heights, you know, the industrial age heights

(18:32):
and how they differed between the classes. So over the
last a hundred and fifty years, um, we have seen
the average height of people and in an industrialized nations
increase approximately ten centimeters or about four inches. Okay, that's
nothing to sniff at, no, no, Now, it's a lot
of people would would pay dearly for an extra ten centimeters.

(18:53):
It's true. Uh, certainly, you know, glued on the bottom
of their shoes. But anyway, it's inner of saying that
this should occur, right because you think that evolution would
be selecting for shorter heights, because based on previous studies,
we know that you find taller heights and fewer offspring
among wealthy industrial British families of the time. Um, but

(19:16):
also you find shorter offspring among the poor, and the
poor are having more offspring. So wouldn't it mean that
the short poor are going to inherit the earth because
they're just gonna outnumber and outbreed the tall rich people. Huh.
But it doesn't seem to play out that way. And
most geneticists you have, believe that it's uh that what

(19:37):
we've seen here, what's been the driving voice and force
and increased heights has been the improvement in shildhood nutrition. Uh,
And that then that has been the most important factor
in allowing humans to increase so dramatically in size. So
there are a few different facts that kind of support this.
So height increases only begin to manifest somewhere around the
middle of the nineteenth century, and we do see dips

(19:59):
in times in places of World war related famine, so
we can see that. Put it out. So here's here's
an area that we saw a significant decrease in nutritional
um quality, and therefore heights went down as well. The
next generation you mean this order, and then the trend
toward increasing height is actually largely leveled off, suggesting that
there is an upper limit to height beyond which our

(20:21):
genes are just not equipped to take us, regardless of
the environmental improvement. Okay, So you're saying like, if we
get improved improved diet and access to healthcare as children,
we're sort of trending further toward the upper range of
natural human height. We're not extending what the range is. Yeah,
there's no there's no quantity of carrots or no quantities

(20:43):
of multi vitamins, they're gonna get you beyond what is
essentially like the normal threshold for what we are as
a species. Right. Um, you know, in the same way
there's not there's not a multi vitamin you can take
that's gonna make you grow an extra arm um. And
also we house it's one of those atomic radiation multi
vitamins from the fifties and uh, and this kind of

(21:04):
goes back to some of the data that has to
do with famine. But conditions of poor nutrition are well
correlated to smaller stature. So we've seen that born out
time and time again. So that's not like a tenuous
hypothesis of modern science. We pretty much know now that
if you're a kid and you don't get good nutrition,
you won't be as tall exactly. So you know, the

(21:25):
the answer there, why why are people taller today? It's
it's as exciting and unexciting as all of that. So yeah,
to answer the question why are people taller than debt
today than they were in the past, While it basically
comes down to nutrition, well that's interesting, but then again
it it makes me wonder how size does vary when
it comes to genetic change over time because like you

(21:47):
obviously do see size changes in the average size of
a population of animals over time. UH, the norm does
go up and down. So what happens there? What when
that happens? How does it happen? Well, one of the
more interesting UH scenarios that occurs it has to do
with the the island rule also known as Foster's rule,

(22:09):
named for J. Bristol Foster in nineteen sixty four. UH.
And this is this has to do with what happens
when you take uh, you know, an existing organism and
landed on an island somewhere. UM. So generally speaking, when
one species arrives on an island, it can change forms
in ways. They don't necessarily generate a new species. So
body size conforms to what we call the island rule.

(22:32):
And it holds true for various vertebrates. So large specimens
they become small, small species become large. And one of
the more extreme examples of this is the the dwarf
is um of megafauna. During the ice age. We saw
dwarf elephants in ice age sicily and the small wooly
mammoths of Wrangle Island in Siberia. So how big were they? Well,

(22:56):
I mean you couldn't fit them in your in your pocket,
but noticeably smaller, like I would say, small enough to
be cute based on the uh, the the average size
of the normal organism. So the basic idea just here
is that smaller creatures get larger when predation pressure is
relaxed due to the absence of some mainland predators, and
larger creatures become smaller when food resources are limited due

(23:17):
to land constraints. That's interesting. So the thing about smaller
creatures becoming larger in the absence of predators, that points
out one natural advantage to being smaller, which is that
it's you know, you're you are not as delicious and
nutritious of a treat, and it's easier for you to hide.
So there there are plenty of selection pressures that would

(23:38):
favor being not as large as one could be, uh
not having the maximum size allowed by your body plan.
And I think that's something that's going to be interesting
to keep in mind, especially for a thing I want
to talk about later on. So I know what everyone's wanting.
How does the island rule affect humans? Well, most of
the time you don't see humans thrown into these scenarios,

(23:59):
and certainly some people may be thinking, oh, well, pigmies right, um.
But in those situations there seem to be a lot
more Um. There are a lot more factors at play there,
including nutrition. So it's difficult to just apply the straight
simplistic island rule to the scenario. But some have theorized
that Homo floresi incests also known as flores Man or

(24:22):
you know, hobbit man. You can probably a popular press,
popular press. Yeah, So some have theorized that this is
an example of of island island rule, island dwarfism at
play with a humanoid creature. Uh. This was this particular
specim was discovered in two thousand three at Langbau on

(24:43):
the island of Flores in Indonesia. And it's from numbers
vary on this. I've seen the number drift in both
directions as additional research has been conducted, but it seems
like fifty thousand years ago is a general timeline we
can stick to. Um. Uh that And there's a two
thousand seven paper that came out title Primates follow the

(25:04):
Island Rule. Implications for interpreting Homo Floresien says by Lyndelle
Broham and Marcel Cardillo, and they argued that that that
that primates do follow the rule, and they used a
comparative database of thirty nine independently derived island endemic primate
species and subspecies to demonstrate that primates do conform to

(25:28):
the island rules. Small bodied primates tend to get larger
on islands, and large bodied primates get smaller. Furthermore, large species,
they argued, to undergo a proportionally greater reduction in the
size on islands. But again that being said, human height
especially as far more complex than this. Uh. Anytime you
take you know, the the human organism, you start laying

(25:50):
over all these various cultural concerns, when you start throwing
in war and UH and and are more complex relationships
with nutrition. Um, it's it's very difficul well to just
apply to rule to humans and in a fast and
slick way. Another thing would be time scales. I mean,
I think that within the time scales we'd be working
with observing human history, there is not nearly as much

(26:13):
time for for significant genetic evolutionary changes to accumulate like this.
So you might you might have for example, sexual selection
among humans or something like that, uh, tending people toward
you know, a certain end of the natural spectrum. But
the time factor is going to cause significant problems for
seeing a large, very noticeable changes in the human genome

(26:37):
over you know, the short period of history we have
access to. YEA. Indeed, all right, we're gonna take a
quick break and when we come back, we're gonna jump
right back into this topic. And hey, we're gonna talk
about phantasm a little bit. Hey, everybody, you know, in
this day and age, you've got to have a website.
You've got to have a professional looking website that represents you,

(26:58):
that represents your work, that rep zon your identity. But
here's the thing. Not everybody has the money to spend
on a super fancy web designer. Not everybody has the
tech expertise to go in there and tinker with a
bunch of code. And that is where square space comes in.
It's easy you create your own website with square Space
using simple, easy to use tools. You can add and

(27:19):
arrange your content and features with the click of a mouse.
You get a free custom domain, you get beautiful templates
to play with, and seamless commerce tools. All of it
works so easily. You don't have to have you don't
have to know code, you don't have to have any
kind of technical expertise because the tools are that elegant.
Plus you have seven customer support to walk you through

(27:39):
any issues. So if you're looking to revamp your current
website or create an all new one for some other venture,
then square space is right here for you, so you can.
You can actually start a free trial with them today
at squarespace dot com by entering our offer code mind
blown to get ten percent off your first purchase. Again,
that offer code is mind Blown squares base dot com.

(28:01):
Build yourself a new website. Alright, we're back, Joe. You've
seen Phantasm right? Oh yeah, h can you refresh the
listeners out there? Um about the details in this cinematic masterpiece, Well,
Phantasm is a horror movie. Don Coscarelli. Is that the
guy who directed it? That's the man? Yeah? Okay, So

(28:23):
the main characters in the oh god, could I even
explain what the plot is? I don't know what the
plot is. That's kind of the beauty out it right. Essentially,
the main characters get chased around by this guy known
as the Tall Man. Who is a grim, dour funeral director,
who who shows his teeth and he squints his eyes,
and he's got lanky, gross hair. And this guy runs

(28:46):
around a cemetery stealing corpses for strange purposes we can
get to in a moment. And he kills people with
a flying silver ball that jams itself into your head
and then drills you with some sort of extremely produce
just blood funnel that just pumps all the blood out
of your head out a jet in the back. Anyway,

(29:07):
that guy was played by Angus scrim And. Uh, he's
the actor who played the Tall Man. He was only
about six four in real life, or so I read,
but they used a bunch of movie tricks to make
him seem taller. I think they gave him tall shoes,
and they put him in a tight suit and stuff
like that. Shot him at the right angles, maybe, yeah, exactly.
But what is the tall Man when we find out
what he's doing spoiler for this nineteen nine movie, when

(29:29):
we find out his whole plot, what is it that
the Tall Man is going about doing with these stolen corpses? Well,
he has a whole industry um and I forget how
many of these details are presented in the first film,
and how many come out in the subsequent films, But
essentially he seems to be from another planet or another dimension,
and he is taking the corpses, crunching them down into

(29:51):
little undead dwarfs that presumably are being sent through this
stargate to serve as slave labor on another in it. Uh.
And the idea here, I guess is that this other
planet has is a is a larger world. There's a
greater gravity, and therefore you need crunched down bodies to
serve as the labor. Uh. He's also I think, using

(30:13):
brains from the corps is to make the flying silver
balls of Death. And of course that this this shines
potential new light on his height. Okay, so he's crunching
down creatures to go to this other world. He's tall
on ours, So does that mean is he is he
shorter on another world? Is he a normal size like here?

(30:34):
So when Superman comes to the Solar System with the
yellow Sun, he gets special abilities. When the tall Man
comes to a planet with much lower gravity in this
sort of relaxed atmosphere, he almost sort of unwinds or
uncoils and grows taller. Yeah, that would be a great
scene for any remake they do where the tall man
steps out of the little stargate here and then you

(30:54):
just his spine elongates like by like a foot or so.
Just god, well, that's funny because it actually is a
fact that human beings grow taller in lower micro gravity environments.
Not that much taller. I don't think you know, a
normal high, average height adult male would reach the size
of Anger Scrim or even uh the size of Anger

(31:17):
Scrim and all of his tall man Kutraman. But it
definitely is true that astronauts, for example, get taller while
they're in the International Space Station. That's right. Uh, And
NASA is known about this for a while. Uh. You
going a trip into into orbit, and you can add
up to three in height while you're up there. So

(31:37):
if you're six ft tall, that's that's two inches you know,
nothing to sneeze that. And that's because when the spine
is free from the constraints of gravity, the vertebrae can
expand and relax. Now, once you get back on Earth,
everything sinks back down to normal, but for a little
bit you gain, you know, maybe a couple of inches
I read actually that once you come back to Earth,
you you return to normal height extremely rapid. It takes

(32:00):
like less than two days. Uh. So when astronaut Scott
Kelly returned from three hundred and forty days in space,
that's a long time he was on the I S S. Uh.
Scott Kelly came back earlier this year in twenty sixteen.
He'd grown about one point five inches while he was
in the I S S. And when he returned his
his normal height was restored within about twenty eight hours.

(32:24):
And of course this would mean the same the same
thing would hold true for low gravity worlds. Take Mars
for instance, which has just one third of Earth's gravity.
Oh yeah, yeah, so that would conceivably be a factor
there if you were to visit it for extended length
of time, and certainly if you're talking about long term
human habitats. Uh. Mars settlement proponent Robert Zubrin, who actually

(32:46):
interviewed a few years back, if very very passionate dude
about Mars colonization like he is, he is of the mindset,
we should, we should be doing it yesterday. Uh. And
here all the reasons we should and we can. Uh. Certainly,
I recommend checking out any interviews with the man who's
very Did he try to sign you up for the
Mars death trip? No, No, that he was. He was

(33:07):
very passionate, because I think it was. There was an
article that I did for Discovery News asking the question,
you know, is it morally cool to terra form another world?
And there were some that are saying, well, no, you
you know you don't. We don't want to just go
will annaling with it with the terraforming. You want to
be respectful, you want don't want to disrupt the evidence
of past life or certainly get in the way of

(33:29):
any present life that might be there or future life.
But Zuber and he presented the opposite to argument that
we should definitely be there. We should go there. It's
a dead world, let's do it. I've actually read a
lot about that. I think that's a very interesting debate,
like what what should be our ethical obligations when dealing
with other planets? Do we have the right to make
them earth too? If we have that ability? Yeah, I

(33:51):
mean we could do a whole episode of essentially on
the prime directive, right, yeah, um, but how does the
prime directive apply to potentially dead world? Yeah, and yet
and who are we to label a world dead, you know,
because we have just have this one idea of what
life is, right. Yeah, So anyway, Zubran has has spoken
a great deal about Mars colonization issues, and one of

(34:12):
the things that has come up is he's theorized that
children born on low gravity worlds like Mars would have
a few inches on everyone else. But you'd have problems
adjusting to high gravity worlds like Earth if you ever
try to go in a pilgrimage here, and indeed you
might not be able to return home at all, or
there might be problems inherently, like even with the low

(34:33):
gravity world. I mean, we've never seen what a micro
gravity or low gravity environment does to a human body
over a really long term. Like the longest we've ever
seen is what happens when you stay in a space
station for you know, a year or whatever amount of time.
The longest space station stay is now. I think Kelly
was up there, if he's not the longest one of them.

(34:55):
But anyway, astronauts report back pain. I don't know if
you've read about this, but you know, according to materials
provided by the I S S Program Science Office, Lower
back pain is sixty eight percent more prevalent in space
than on Earth. And is this caused by the lack
of the intervertebral discompression due to gravity. It's the same
thing that makes you taller, the same thing that makes

(35:16):
you taller. Actually, when you're lying down horizontally as you
sleep at night. In the morning you get up your
taller than you were when you went to bed. Uh.
Does being separated from that that downward pull of Earth's gravity.
I mean, obviously we didn't evolve to be like that
for long, long periods of time, So what does that
do to you? It it might have some less than

(35:36):
positive effects. Yeah, And certainly every human child ever born
has been born on Earth. No one's ever been born
in space, so we have no idea what human development
might be like you a lower uh, lower gravity scenario. So,
with all of those concerns in place, and the idea
that being raised in a microgravity environment might really mess

(35:57):
you up in all kinds of ways, it is possible, Bowle,
that growing up in low gravity or microgravity might make
you taller. Yeah. Maybe so, so if nothing else you
could you could you could cling to that reassuring fact
because as we've touched on already. There's a lot of
there's a lot of weird human hang ups when it
comes to height. And there's an entire psychology to human height.

(36:18):
Oh man. There there are a bunch of studies looking
into this. Uh and and it kind of makes sense
why there would be a strong psychology of height. You know,
height is a primal survival signifier, right. It advertises physical strength, reach, health,
and good nutrition. And so for this reason, I think
it's not surprising that humans have some natural tendencies when
it comes to our psychological relationship with human height. I

(36:41):
think there's uh there. For example, is this pervasive notion
that taller people have more social and economic success, that
they're more persuasive, more impressive, that they you know, they
just get they're just go getters and the all good
things come to them. In fact, I remember I had
a teacher in high school who who told us one time.

(37:04):
I don't know what his source was for this, Maybe
it was just his own wisdom, he was making it up,
but I remember he told us that that if you
want to if you want to persuade people or to
be a good leader, the most important thing is height,
and the second most important thing is being funny. I
think the emphasis being on how well, if you're not tall,

(37:24):
you better darn well be pretty funny. Well, I mean
that makes sense. Look at Jeff Goldbluin, seems like a
funny guy, very tall guy. I'd followed him anywhere. Yeah,
he could. He could tell us all to jump into
a volcano, and I'd be pretty sure he had a
good reason. But anyway, is there anything true to this
or is it just another unsubstantiated folk myth based on
our biases. So there was one huge landmark, highly cited

(37:49):
paper from two thousand four about this in the Journal
of Applied Psychology by Timothy A. Judge and Daniel M. Cable.
And they did this deep investigation on the you know
what could be known at the time about the correlation
between height and success, and they certainly did find a
strong correlation between the height of a human and for example,
career success. And so it was summarized by the American

(38:12):
Psychological Association as with this startling fact, for someone who
is six feet tall, they earn on average a hundred
and sixty six thousand dollars more during a thirty year
career than somebody who is five feet and five inches tall,
even when controlling for other factors that could contribute to that,

(38:33):
like gender, age, and wait, they found that taller men
and taller women are both more successful in their careers,
but that the correlation is stronger for taller men. And
they're fascinating questions that come along with research like this
because all, you know, what they can establish is the correlation.
They can't necessarily show exactly why this is true. Uh

(38:53):
So you could have lots of hypothesis hypotheses, Like some
people would say, is it true that taller people are
smarter and that's why they make more money? And that
doesn't appear to be the case though that I think
there have been some studies attempting to link height with
intelligence that they didn't find that that that was the
primary explanation. Uh So, could it be that taller people

(39:17):
are just respected more by others and you know, the
boss looks at a tall person and says, you look
like you deserve a raise, or could it be that
the way tall people are treated by others leads to
more self actualizing behaviors and you know, makes people more
confident go in and ask for the raise more often there.
There are a lot of ways you could try to

(39:38):
explain things like this, like maybe in a cubical environment,
when they stand up, it's easier to see their heads,
so the boss that sees them more often, or perhaps
their brain is closer to Heaven just by virtue of height. Yeah,
how does this all make you feel today, Robert? You're
being one of the taller people in our office? Um?
You know I do. I kind of like second guess

(40:00):
the role of height a lot in my daily life,
you know, like I like I find myself second guessing, um,
you know, things that go right, or I'm like, oh
did this didn't did my height play into this? And
then I started thinking of studies like this, and it's like,
is this just all a virtue of me being a
little bit tall? Um? And then and then of course
I curse my height when I bump into things. And

(40:22):
then I then I wonder like, well do I I
actually end up looking like like an ungainly tall person
as I'm walking around the office. And therefore I'm like
I don't fit in as well, like I'm more of
a like a freak. You know, Yeah, you really are? Well?
Thank you? Oh no, I mean being tall might be
another one of those things where we discovered that there

(40:43):
are just natural biases at play, for example, like the
natural advantages or privileges some people might enjoy for being
male in the workplace. You know, sometimes you're just gonna
be treated differently and you might benefit from that. Yeah,
And I guess like you just end up it's like
second guessing, like how everyone around you is interpreting things,
Like I've often found it weird, like I've always been

(41:05):
taller than my bosses. And obviously being tall has nothing
to do with being or being short in height has
nothing to do with your ability to lead in a
workplace or being effective boss. But for some reason, there's
always this like weird, Like I don't know if it's
like a grade school or lizard brain voice in the
back of my head. It's always like like, is this

(41:28):
weird that my boss is shorter than me? My boss
gonna hold it against me because I'm taller, like as
if as if like one if one gave man is
going to rise against the others, like he must be
punished because he was taller than me. But still like
you can't help, but but here those just nutty paranoid
voices from time to time. That's great, Robert. I hope
you will always share what these voices are telling you

(41:50):
with me like I had. It probably has to be
the same for people with great beards, um um. And
you have pretty great beard yourself. I don't know about that.
I do not grow that that great of a beard.
So if I had, if I were to have a
great beard, and I was to have a boss with
a lesser beard like that would feel a little weird,
like I would. I don't want my my beard to
get me in trouble because of its boldness. Uh. Yeah,

(42:11):
Well the beard and the and the height thing again
this comes into I wonder if this is uh, this
is natural sexism in our mindset also playing into because
of the sexual dimorphism of height, the fact that on
average men or taller. I wonder if sexism also plays
a role, Like if height in some way manifests in
our minds as some attribute of manliness, And because we

(42:33):
have this unconscious bias favoring manliness, is that another reason
that we pay tribute to the tallest? Yeah, the tallest
and an accidental invader Zim reference there where the the
leaders of Zim's race alien invader race um. They are
called referred to as the tallest. They are the tallest
of their species, though clearly they've been augmented with with

(42:57):
outfits and machinery to make them appear. Oh they're cheating.
Oh yeah, they're cheating, and they're lifting. Yeah, they're definitely lifting. Uh,
but yeah, that's the tallest. Well, this brings us to
the question I think that maybe we could conclude with,
which is how tall exactly could humans grow? We've talked
about how humans have gotten, on average a little bit

(43:19):
taller over time, though this doesn't seem to be from
you know, serious genetic mutation or revolution, but more through
nutrition and access to healthcare. But imagine we were, for example,
able to genetically alter the human race. You know, we're
going to go in and tinker with our genes and
try to create the world's tallest human. Could we make

(43:41):
a human that was like Glenn Manning. Could we make
a fifty foot human? Could we make you know, Attack
of the fifty Foot Woman. That's another b movie about
the giant human. Could we make a hundred foot tall human?
Or even just being more modest, could we make up
fifteen foot tall human? Are are any of these things
really possible or would we hit insurmountable problems. Well, I

(44:04):
guess it's easier to shoot down the more extremes first, yeah,
and then and then scale back down, because yeah, when
you're talking about Glenn Manning, when you're talking about Godzilla,
King Kong, any of the or any of these various
giant creature movies we've discussed already, Um, there are engineering
limits to the body size. Yeah, and I would totally

(44:26):
agree with that. I think that Unfortunately, for the people
who want to, you know, change their their genetic code
to be twenty ft tall, it's just not gonna happen.
That's just not the way humans are gonna work. And
we'll try to explain why. So. The tallest man who
ever lived, as far as we know, was a guy,
an American guy named Robert Wadlow, who at the time

(44:49):
of his death was eight feet and eleven point one
inches tall, as almost nine ft tall two hundred and
seventy two centimeters. That is so tall. If you see
pictures of this guy, you're probably not imagining him tall enough. Uh,
look up a picture, You've got to see it. Wadlow
died at the age of twenty two though, unfortunately, and

(45:12):
he had serious health issues that seemed to be associated
with size. This might come as a surprise because our
natural intuitions, as I've said earlier, sort of, I think
we group height as a health indicator. We think of
somebody who's very tall as somebody who's strong and healthy,
and you know that they like their body is doing good.
But the issue with Wadlow was that he he encountered

(45:35):
multiple problems because of his size. His He suffered from
a condition where his body produced excess growth hormone, and
it was continuing to produce excess growth hormone as he
kept growing, and this just kept making him larger and larger. Yes,
I believe the condition here is the acronola. Yeah, yeah,
I think so. But anyway, so he had problems and

(45:56):
for example, what led to his death was that Wadlow
an infected blister on his foot from braces that he
had to wear on his legs because of his size.
And one of the problems that he would have is
that he had very little sensation or feeling in his
lower limbs. Again probably because of his size. The body

(46:18):
is just not built to be that big and in
many cases the supporting organ structures can't accommodate it. Uh,
And so he got an infected blister that he wasn't
really aware of because he had this lack of sensation
in his lower limbs. And he died at the age
of twenty two. And also I've read in several places
that there was no sign when he died at the

(46:39):
age of twenty two that his growth had stopped. He
seemed to be still growing. So that's a sad story,
but it doesn't introduce the idea that there are design
constraints essentially on the human form. Yeah, I mean he
You can also look at at other cases of acromegalay,
at cases of gigantis and acromegalay in particular layer which

(47:00):
is again this has caused when the anterior pituitary gland
produces um excess growth hormone. UH. This can result in
a number of different symptoms such as severe headache, arthritis,
and carpal tunnel syndrome in a large heart, liver fibrosis,
bile duct hyperplasia, hypertension, um diabetes, heart failure, kidney failure,

(47:23):
as well as cancer and loss of vision. Because again
it's just the design constraints. I often think about this
in terms of like a business scenario. So say you
have a food truck, right and you want to evolve that.
You want to grow that into a you know, a
brick and mortar restaurant, and for there, you want to
grow that into a restaurant chain, and from there you
want to grow it into a restaurant franchise. Each of

(47:45):
those is not just a larger version of the preceding form.
Each of those is a a more complex system um
and and if you attempted to do to to achieve
the goals of one with the with the smaller form,
there would be massive problems. Yeah. I think that's a
really good example. And the one I was actually going
to use was the comparison of just regular buildings, like

(48:09):
building a house versus building a skyscraper is a completely
different type of project. It's not just a question of
scaling up the house. You can't use the same materials
and techniques that you would use in building a house
to build a skyscraper because it's not gonna work. I've
I've had to research skyscrapers for the other podcasts that
I do here on uh how Stuff Works, on forward Thinking,

(48:32):
where we talked about the future of skyscrapers, and one
of the things that impressed itself upon me from that
is that skyscrapers aren't static. They're not like a building.
They're really more like a giant machine because you have
to keep in mind all of these incredibly voluminous uh
amounts of things that are coming in and out, all

(48:54):
of the heating and air, all of the plumbing, plumbing,
you gotta have pumps that get stuff up to the
top of the skyscraper. Just the transportation of people exactly. Yeah,
elevators managing elevators, Like so, if you're in a hundred
story building, can you just have normal elevators that go
up and down like normal elevators? How long are you
going to be on the elevator if you're trying to
get up to an upper floor. Uh So, you know

(49:17):
they've got to have design considerations like that, express elevators
and different types of elevator lobbies and stuff like that. Yeah,
I could remember correctly. This is like one of the
major design problems with the highly conceptual um Illinois mile
high skyscraper that Frank Lloyd right designed, because you know,
tremendous mile high in the sky. But then when you

(49:37):
start breaking down how people are going to get to
the upper floors, how many elevators you're going to need,
that's when you run into the real engineering problems that
prevents such a structure from coming to reliship. What do
you do if there's a fire drill? Yeah, I mean
it's hard. It's bad enough when you just have a
what you know, fifteen or those stories, yeah, much less

(49:58):
a mile of skyscrape are up there. Yeah, So we
should actually get into some of the examples of why
it doesn't make sense to just continue scaling up the
human body from its normal size. Indeed, so there's a
as an offer by the name of our McNeil Alexander,
and he has a wonderful article titled engineering limits of
the Body Size of land Animals. And this is actually

(50:20):
available in a couple of different forms. I have it
in a big book of scientific essays about like big
questions about life on Earth. But he uses the example
of King Kong. King Cong is a great example. It's
a giant gorilla and uh as as you know, as
as most people are aware. Yeah, but I thought it
was a giant human and a gorilla costume. No, no,

(50:42):
it's it's it's a real gorilla now. But King Kong
as a giant gorilla. If if he were to step
off of the screen and exist in our real world,
he would collapse under his own weight. He would be
one hundred and twenty five times the volume of a
real ape loaded with one hundred and twenty five times
the weight of a real gorilla, and his legs would
just simply snap like kindling. So one way to look

(51:05):
at this is to apply the spherical cow example. And
what you've heard of us about you've heard about spherical cows, Okay, well,
spherical cows in general concern. It's sometimes for any time
you take an engineering problem and you like simplify something
like we're talking about a cow, so will just make
it a sphere so as to more easily talk about it.

(51:28):
And sometimes it's a criticism of sort of physics approaches
to solving problems, but it actually works really well in
this scenario. So assume the cow is a sphere, right,
So as the sphere gets bigger, it's volume increases more
rapidly than its surface area. Double the radius of a
sphere and the surface area increases four times, and the
volume increases eight times. So double something size and keep

(51:50):
its proportions the same. Its weight doesn't double or even quadruple,
it increases by a factor of eight. This gets into
situations why you would to to take a small creature
and make it bigger. You would have to drastically change
its proportions to support the weight. So you know, Keen Kong,
a giant human. The basic morphography of the creature would

(52:12):
have to upgrade as well. Yeah, okay, so the strength
of the molecules and the bonds that make up your
bones is not going to get proportionally stronger. It's gonna
be You're dealing with the same molecules either way, and
the same issue as you'd be dealing with the same
energy constraints either way, right right, Like, So a proportionally
voluminous creature like this would have proportionally great energy needs

(52:35):
and ways of dissipating excess heat energy to right, Yeah,
it would just have to eat more bananas. You'd have
to take into account. It's hair, you'd have to take
into account, it's metabolism. So, as arm McNeil Alexander points
out in his article, uh, a mammal one five times
heavier than its original form, would need to metabolize forty

(52:56):
times as fast, which means Coong would have to lose
x has heat from his skin, which has only twenty
five times the area of a real to eight skin
due to proportions, and he has all that super thick
fur five times as thick as a real guerrillas, which
is not going to help matters either. So not only
would call collapse under his own weight, he then overheat
and die right there on the pavement before he could

(53:19):
ever climb the skyscraper. So then what's going on with
these incredibly large animals that we do see, like, for example,
I I'm excluding water dwelling animals because once you're living
in water, that seems like that's a very different kind
of environment and different things are possible. But but these
land dwelling animals, like the largest sauropods, big dinosaurs, what's

(53:40):
going on with them? Well, I mean it's it's ultimately
going to be more a matter of what's competitive in
the struggle for existence, as as Alexander points out, because uh,
I mean that's gonna be the deciding point. Can the
can the market bear it? Can the can the market
allow a restaurant this huge to exist. Um, you know,

(54:00):
it's it's similar to the giant aircraft. Right, there's certainly
giant aircraft that can be built, but will they be built? Well,
is there actually a reason to build it? And then
if built, is there going to be a reason for
it to remain a part of our aeronautic um you
know Kingdom? Yeah? Yeah, yeah, yeah, I wonder And now
I've not looked this up. It just occurred to me.

(54:20):
I wonder if there's an upper limit on the mass
of a thing that we can make fly? Is there
just an object so heavy that there's no way to
make a vehicle this heavy fly? That's a good question. Yeah,
what is the what is the heaviest possible air vehicle?
This would be a fun one to explore, especially in
light of you know, some of these Marvel films that
have come out with the like the aerial aircraft carrier ships.

(54:45):
You know, well, I mean I guess it would. It
would depend on whatever is the maximum limit on the
the opposing forces that we can create. I'm assuming we're
not using like gigantic balloons and stuff like that. Going
with with with fat s flying airplane style, Yeah, balloons
tend to be the best way to get them up there.
Failing that magical anti gravity. Yeah, but I think it

(55:09):
should be clear at this point that you can't just
scale up the form. And uh and and you mentioned
also one thing about insects, right, this this also applies
to other films of the nineteen fifties, right. You know,
you've got the Giant Spider Invasion Earth versus the giant
spider huge ants in them them as huge ants. They're

(55:29):
big bugs everywhere. Yeah, I mean even things like I
hesitate to drag those xenomorphant into all of this. But
take say the Gartham from the Dark Crystal, you know,
giant presumably exoskeletal creatures, or the giant crabs of of
of various beloved works of British horror um. These largely

(55:51):
just don't work when you start blowing them up that
big because they're exoskeletons. Would have to just get increasingly
and eventually impossibly thick to support them, because the exo
skeleton is not just armor, it is a skeleton. It
is a supportive structure. Yeah. And if you'll allow me
to go on a quick tangent from human height here
I do. I looked into this a little bit because
I thought this was interesting. I was wondering, why don't

(56:13):
giant spiders exists. I'm not sure exactly what the limitations
on the upper on the upper end of insects and
spiders are. Could we have bert I Gordon's giant grasshoppers
and stuff like that. And my guess was that it
actually might have something to do with their open circulatory system,
being you know, spiders and insects don't have full body

(56:35):
blood vessels like we do that maintain blood pressure and
keep everything going to the right place. They've got open
circulatory systems, meaning they might have some main artery just
like one big one or something like that, and then
through a lot of the body cavity the body fluids
in the blood or they don't have blood exactly like ours,
but their oxygen distributing juices are just kind of loose,

(56:57):
they go wherever. It seems like that system works less
and less well the bigger you get, the more you've
got gravity pulling down on those body fluids. But anyway,
I decided to look into this, and what do you know,
I could not find any scholarly articles on why insects
and spiders can't grow to the size of tour buses. Uh.
This seems like a massive oversight. Somebody needs to start

(57:17):
a peer reviewed journal for this. But I did find
some pop science articles that at least interviewed some insect
physiology experts to get their informed opinions. And so there
was a twenty twelve piece on Science World that spoke
to a few experts about why we don't encounter giant spiders. Uh.
The spider systematist Wayne Madison of the University of British

(57:38):
Columbia just suggested the general issue of scaling like we've
been talking about here. A guy named Rod Crawford at
the Burke Museum in Seattle suggested that the main problem
could be respiration. Actually, because the spider has to oxygenate
its tissues and purge carbon dioxide through a system based
on breathing tubes called trachea and book lungs and also

(58:01):
copper based blood, and its respiratory system just would not
scale up because it couldn't get enough oxygen to all
the parts of its body fast enough. And the author
points out that this could be the reason we see
fossil evidence of much larger insects like you know, those
huge hawk sized dragonflies living at a time when Earth's
atmosphere was more oxygen rich than it was today. So

(58:24):
there used to be a higher composition of oxygen in
the atmosphere, and so these less efficient uh, you know,
bug breathing systems could could get more oxygen to more
tissues that way, allowing a bigger bug. There was also
a twenty twelve article in Live Science that interviewed an
insect physiologist named John Harrison at Arizona State, and he

(58:44):
had a couple of hypotheses. He mentioned the exoskeleton limitation
problem that we mentioned, but he also notes that one
city has shown that exoskeletons don't necessarily become thicker as
insects get larger, so this may not actually be the constraint. Uh.
He also he points to the open circulatory system that
I mentioned as a potential problem. Uh. He also mentions

(59:06):
the respiration issue and uh, and these these ancient dragonflies
that existed three hundred million years ago that could have
these giant wingspans, huge bodies run around preying on other
on other animals. But finally he's he suggests something that's
interesting to me, which is that it's uh, not just
a physical architectural constraint, but an evolutionary constraint. This came

(59:28):
up earlier when we were talking about pressures on the
island rule. You know, why might why might uh? Sometimes
animals want to be smaller and he he mentions that
bigger insects prove more enticing meals to insect eating predators
like birds and mammals, so they've got more nutrition in them.
They're they're just better to eat, and it's harder for

(59:48):
them to hide and go out and noticed. So there
could simply be a strong selection pressure against larger insects
and spiders based on the rate of predation. There's just
so many predators out there air. It just doesn't it
doesn't pay, evolutionarily speaking, to get bigger. And so finally,
I want to conclude with the idea of I wonder
if there's anything like that that applies to human beings

(01:00:13):
other than just the limits on what's architecturally possible with
our body plans as they are. Are there any selection
pressures that would keep humans smaller? I mean, it can't
tend to think of any, but that doesn't mean they're
not there. Maybe I just don't have enough imagination on this,
like scenarios in which a larger person would would not

(01:00:34):
have a like a breathing advantage exactly. Well, I mean,
we're at the top of the food chain and have
been for so very long. It's hard to imagine predation
playing in you could I mean, I guess you could
maybe make a case for uh, sexual compatibility between males
and females in some scenarios without you know, getting too

(01:00:56):
nitty gritty and the details. But I mean, I don't
know that could conceivably be an issue if two creatures
cannot physically engage with each other, um, you know, that
could become that could that could apply at some pressure
on the evolution of the form. Yeah, yeah, I mean
I can't think of anything really, but I uh, but

(01:01:17):
I wonder maybe you listeners out there have some ideas
what what could be any possible evolutionary selection pressures favoring
a smaller human being? Mm hmm. You know, I'm instantly reminded,
of course, of of just in terms of dimorphism here
of a cuttlefish, various cuttlefish where you have both the

(01:01:38):
large males and the smaller males, both vying to breed
with the female, and the larger male breeds by just
sort of you know, fighting off competitors. Then the smaller
male will use deception, will sneak in there, will pretend
to be a female so as you get closer to
the female, sometimes taking on the appearance of a male

(01:01:59):
on one side of body while taking on the appearance
of the female on the other side, and getting in
there close enough and then breeding with the female while
the big scary male is guarding it. So this being
an example where you see both big and small bodies,
both large and small forms having reproductive advantages. So that's

(01:02:21):
one possibility that's fascinating. I hope that doesn't so much
apply to human being. I don't think it's It applies
one to one to the complexities of human human love
and human reproduction. But it's worth keeping in the back
of your mind. Yeah, or anything else. I think that's it.
I mean, we covered everything from phantasm to the amazing
colossal man, from giant spiders to giant guerrillas to people

(01:02:43):
in space, so I feel like we, uh we we
did it justice. In the meantime, check out stuff to
about your mind dot com. That's We will find all
the podcast episodes, videos links at our various social media accounts,
blog post, you name it, it's all there. Hey, wherever
you listen to us, whatever me you have to get
this podcast. If they have a way to leave a review,

(01:03:03):
give us some stars. What have you do that, because
that's a great way to support this show. Um tweet
various algorithms and ensure that we can give you episodes
each and every week. And also if you want to
get in touch with us about this episode or any other,
you can always email us at below the mind how
stuff works dot com for more on this and thousands

(01:03:31):
of other topics. Does it how stuff works dot com