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Should We Have Left the Water? | Hank Green | YouTubeToText
YouTube Transcript: Should We Have Left the Water?
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Core Theme
This content delves into evolutionary biology, clarifying concepts like neofunctionalization and exaptation, and exploring the transition from water to land, adaptations of various species, and the observable nature of evolution in real-time.
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There's only three more days left to get
this shirt designed by Matias Ball
because I wanted it to exist and now it
does and we're making exactly as many as
get ordered during the pre-order period
and then we cut it off and that cut off
date is 3 days from now and I wanted you
to know that so you don't miss your
chance. I got so many questions so many
questions on that video and so many of
them were very good. I again it makes me
want to write this book. But one of the
things people brought up and I have not
yet read it though I have gotten it on
Audible is your inner fish by Neil
Schubin which is a book that is kind of
about this. It's not entirely about
this. It's not like just about the
transition to land but it is about a lot
of the same stuff. So if you want a book
like this that book exists but I have
taken 48 screenshots of questions.
There's no way I'm going to be able to
make it through all of those. But let's
just start. Let's just start and see
what happens. Most importantly is this
the same thing as exaptation? No. And
indeed, I used neofunctionalization
incorrectly several times in that video.
Now, I'm not that worried about it. I
didn't like make one little edit in the
video to fix a particularly egregious
instance, but exaptation and
neofunctionalization are two different
terms for similar phenomenon.
>> Neofunctionalization is specifically a
genetic term when a gene duplicates and
then there's two copies of the gene and
then the new copy starts to do something
new. This happened with keratin a bunch.
keratin. There's a bunch of different
keratin genes that do like different
versions of keratin and each one of
those is a duplicated gene that then
took on a new function. Exception is
sort of a broader term for when some
existing physiological structure gets
used in a new way. I use that
interchangeably with
neofunctionalization which technically
is not something that you should do. Do
whales and company have to unchange the
shape of their cornea when Oh yeah, they
did. They did this. Yes. Not only that,
whale eyes, seal eyes, penguin eyes, all
did this. Not only did they change the
shape of their cornea when they went
back into water, they changed the shape
of the lens back to a sphere. They all
of them did this. Isn't that amazing?
Independently, like these are not
related animals. Citations and seals and
penguins are not related. Why did our
ancestors try and die doing this? I've
always understood evolution to be lazy
and that it only does what is necessary
for survival. Why did our ancestors/evolution
ancestors/evolution
want to attempt this feat? Was it to
escape predators? It was a survival
advantage. I probably shouldn't have
said it this way that like did they die
doing this? Yes, of course they died do
doing this, but they also survived doing
it. So, there was an ecological niche
that became available to them when they
were able to move on to land. There was
food there that they otherwise would not
have access to. And the animals that
could get access to that food were able
to make more of themselves. It was a
success. They were more successful if
they were able to get onto land and eat
the bugs that had never seen a
vertebrate before. Eat the plants that
were not being eaten by anything and had
no no mechanisms to prevent themselves
from being absolutely delicious and full
of calories. There was a bunch of
survival advantages to coming onto land.
And and most of these I mean all of
these early animals didn't just go onto
land and stay there. There's kind of
this idea of Tik Tok being like it
dragged itself out onto land and it's
like I'm a land animal, but there was a
huge amount of time during which all of
these animals spent some time on land
and some time in water. And then over
time, you know, that the ability to stay
on land for longer increased because the
further you could go onto land, the more
value there was in staying on land, the
more of a new niche you could move into.
And so every step further, there was a
huge incentive to take that step because
there was food there. Um, there were
also no predators. But I think that the
big thing was the amount of food that
they otherwise wouldn't have access to
or that was being competed for when they
were in the water. Yo, is that shelf in
the background broken? No, it was it was
built that way. I wanted it to be weird.
And it is. I don't I can't actually
change the angle of this. I can do a
phone video, though. The kind of idea
when we were designing this uh was like
uh my office crashed into an office. So,
I get that it looks broken, but this
part over here is all slanty. And then
this part here is straight. Straight is
actually much more useful, much more
functional, as you might expect. There's
other uh slanty. There's slanty shelves
over there. There's a shelf in the
ceiling, which I love. I need to fix
that soundproofing, but you know, this
is I found this light fixture, which
kicks ass. I honestly kind of wish it
was broken. Like what my dream was to
find a bunch of shelves and then mash
them together, but that turns out to be
much harder than building them from
scratch. We have experimented with
putting glasses that flip vision upside
down on people. And after enough time,
they adapted and everything now seemed
to be the right way up for them. Could
the same happen with underwater vision?
No. So in that case, the light was still
focused on the point it was supposed to
be focused on. In the case of going
underwater and having vision, the light
doesn't hit in a point. It doesn't
focus. It hits broadly. And taking that
information and forming that into
something useful is not as far as I know
something that can be done through like
post-processing, which is this is like
the brain doing it rather than the
actual function of the eyeball. That's
something that has to be fixed like in
the camera. Like if your camera's out of
focus, you can't get it in focus with
enough brain power. You have to have it
be in focus. Since we're still saltwater
sacks, why salt water dehydrate? I
understand there's like a concentration
gradient thing involved, but I don't get
it. So, we never left the water. But
importantly, we did actually leave the
ocean. So, I fudged over this. The
ancestor of all the tetropods was not a
saltwater ancestor. It was a freshwater
ancestor. And this makes sense for a
number of different reasons. First,
because of breathing. So, these lungs
started to increase in capacity. They
started become more useful because there
was a situation where there wasn't a lot
of oxygen in the water. And that doesn't
tend to happen in salt water that much.
Does sometimes, but not usually. tends
to happen much more frequently in fresh
water. Second, another bunch of stuff
that I did not talk about in this video
was like temperature swings and how
important that was for leaving the
water. So, tetropods when they were
first like going on land a little bit,
it would have been really hard to do
that from the ocean. And like you can do
it, crabs do this. Crabs have all kinds
of ways to deal with big swings in
temperature, but if you're just in the
ocean, the temperature swings are very
mild. And if you're on land, the
temperature swings are massive. But if
you're in fresh water, the temperature
swings in fresh water can be pretty
significant. And so it makes some sense
that the animals that would leave the
water would be once they were already
somewhat used to larger swings in
temperature, which is more likely to
happen in stagnant freshwater than in
the ocean, which is very big and has
lots of mixing from lots of depths and
has a more consistent temperature. And
there were other reasons for why
freshwater lobe finned fish were I think
like kidneys. So kidneys were very
important. Freshwater fish had to evolve
kidney-like structures so that they
could sometimes deal with the extra salt
that they would encounter in brackish
environments. So kidneys might actually
there were people in the comments who
made the case that kidneys are the
bigger difficulty than skin which I'm
perfectly open to and maybe that
question will come up in this list. What
is the second favorite fish? I can't
make it out in the picture. Uh my first
favorite is the angler fish and I should
make a video about both of these fish.
My second is the mulamola which I love.
People hate the molola. They say so many
mean things about it, but it is it is so
weird. It's the animal that goes like it
increases in size the most over the
course of its life. I love that. I have
a question. Can we see evolution
happening even now? Do we see things
that are documented differently 100
years ago or does evolution take longer
than that? We do see evolution happening
even now. There's like this famous moth
that has shifted its coloration as the
colors around it have shifted and then
actually shifted back. I think this was
a thing with like uh coal soot getting
on trees and the coal soot got on the
tree trees were darker and so they
became more visible and the ones that
were darker and more closely matched the
color of the tree were more likely to
survive and over the course of time they
shifted to darker and now there's not
that cold sod anymore. Am I making this
up? I should check. Peppered moth
evolution. Yeah, the evolution of the
peppered moth as an instant directional
color change in the moth population. The
consequence of air pollution during the
industrial revolution. I didn't make it
up. This is great. There's also
antibiotic resistance in bacteria.
That's obviously evolution happening
very quickly. There's also examples that
are are on shorter time scales but still
very long, like longer than human
memory. Darwin's finches uh probably
have been on the Galopagos, like the
first finch arrived there about a
million years ago. And then all of its
ancestors, there's a bunch of different
species that are all descended from this
one finch that arrived just a million
years ago that have very different
physiology in order to take advantage of
different niches in the environment and
different food sources. My favorite
example is actually an artificial
selection example. And this has happened
over thousands of years. So, this is so cool.
cool.
Got to make a whole video about this.
Wheat. We had wheat. We started doing
wheat agriculture. And we would weed the
wheat fields so that all of the plants
that weren't wheat weren't competing
with the wheat so that we would just get
wheat because we just wanted wheat so
that we can make bread and beer out of
the wheat. But you may have heard of
buckwheat. Buckwheat is a grain crop
that is super useful and it looks a lot
like wheat, but it is not like wheat. In
fact, it's gluten-free, which is why a
lot of people use buckwheat when they're
making pancakes or something for people
who are allergic to wheat. Buckwheat was
a weed that grew next to wheat. And when
we weeded the wheat, the buckwheat that
looked more like wheat was less likely
to get weeded by humans. And over
generations that weed bred in like
intermixed with different buckwheats
that looked more like wheat to the point
where buckwheat and wheat were almost
indistinguishable from each other. And
the wild thing that this created was not
a huge problem. It was an entirely new
edible crop. We artificially selected it
by accident so carefully to look like
wheat that it became a food. We we made
it a food by accident because it
couldn't look more like wheat without
getting the attributes of becoming more
nutritious and having bigger seeds that
like all the stuff that we were
selecting for when we were looking at it
when we were weeding actually made it
into a useful crop. So that's amazing.
That's not an example of natural
selection. It's artificial selection,
but it is kind of natural selection
because it wasn't done on purpose. It
was done by just a an animal. It's this
weird in between crease that's not quite
natural selection, not quite artificial
selection. Anyway, takes a long time for
evolution to happen, but like not so
long that we can't see it happening.
Could intelligent life evolve
underwater? It has a bunch octopuses,
man. But I think that um a more
interesting question, which is probably
the question you're asking, is could
like a civilization develop under a
water? And I don't know that it could. I
think that there might be limitations
there, specifically when it comes to
building. Yeah, I like I know that
people have written science fiction
about this, but chemistry is is hard is
easier on land. That's a weird thing to
say. Obviously, chemistry is easier in
the wet, but it is easier to control
things. It's easier to control your
environment when you're in a dry place
that you can figure out where the
different wetss are going to be and what
you're doing with it. I'm I know I
always come at these questions from from
a chemistry perspective, but like it
would be basically impossible to develop
the technologies we have developed while
underwater. And I think that that's
seems real. When talking about evolving
digits, you made a point to say on both
front and rear extremities, which makes
a lot of sense, but I had never even
thought about them evolving
independently. So now I can't stop
thinking about how we have the same
number of digits on both. Is that like a
weird coincidence? No. We use the same
genes to do both the left and the right
hand. We're not there's not like a
separate set of genes for them. We also
use the same genes to do the legs and
the feet. Like obviously we have like
different structures. But overall like
you know you have two bones here and you
have two bones here and you have like
one bone here and one bone in the femur
and then you have like all the different
metatarsils and digits and have the same
thing going on down there. Now this
isn't always the case. you can make
changes to that and obviously like these
are basically exactly the same mirror
images whereas the feet are quite
different but there are like the the
base level genes they're called hawk
genes that determine body plan we use
them over and over again and in fact we
don't just use them over again they're
used over and over again throughout the
history of life like the hawk genes for
lobe fin fishes are the same like this
like fairly well conserved from then to
now like weirdest uh version of this you
can take the hawk gene for a rabbit's
eyeball and put it in a fly genome where
it would normally express a part of the
butt and it will grow a fly eyeball on
the butt. Absolutely
one of the coolest things I've ever
heard about. Bro, just accept it was God
doing all this and stop confusing
yourselves and everyone. This is one of
the reasons why I don't like God. He
explains too much. If we take God and we
say, "Wow, good job explaining all of
this." We miss things. God is an answer
that answers every question. And if we
have an answer to every question, then
we stop looking. And I don't know that
even if like God exists that that's what
he would want or they would want or it
would want. I don't know what God is to
people. It seems that like there's a lot
of really interesting stuff here and so
we should indeed keep looking. That's
how I feel. Another person asked, um,
where does God fit into all of this? And
like, for me, obviously, nowhere. But
for you, anywhere you want God to be.
Like, I think that there's lots of
places for God to be. Maybe God isn't in
this story, but he's in another story
for you. Maybe he's in why we're
curious. Maybe he's in why anything
exists at all. Maybe he's in love. Maybe
he's in the relationships between you
and other people. I think God can be all
kinds of different places. Is it just
easier for arthropods to stay dry or is
that its own crazy story? It is its own
crazy story. And of course, they had to
independently evolve air breathing as
well, but staying dry was a really big
deal. Holding on to water was a really
big deal. For the bugs, they obviously
were able to do it before us. But yeah,
they did have to do specific things
evolutionarily to make it so that their
bodies weren't porous. They like figured
out how to coat their kitan in like a
waxy substance that held all of the
water in and also their joints. special
things have to happen with their joints
so that they wouldn't lose water. But
yeah, diff totally different story uh
and also a crazy one. And this is the
thing that I think would separate what I
would like to write or that I hope
somebody writes for like from the inner
fish which is more about like our bodies
and how that journey is represented in
us. But I would like to tell that story
of how everything like plants, bugs,
fungi, lyken, humans, like all how
everything went from this much more
hospitable environment to this
extraordinarily hostile one and and took
over that. And um and also like honestly
I going to make this video at some
point, but uh I think land is is
potentially a solution for the firm
paradox. Like land might be very rare
and also might be necessary for not
intelligence but civilization for
chemistry reasons interestingly but
that's just my thoughts
and that's not for this video. I'm
curious how many times an organism's
lineage has gone back and forth between
water and land or what is the organism
that we know has gone back and forth the
most times. So obviously tetropods came
onto land and then we went back into the
water as whales citations. Um and I
think that this has happened. So, uh,
roly polies. So, uh, uh, what are those
called? What are they called?
Uh, isopods. Isopods were originally
marine and they are also not marine. Uh,
they're with they're isopods that live
on land. But those land isopods have
gone uh back into freshwater. So, that
has definitely happened just like
mammals. But, I think there might be a
case where a freshwater isopod that came
from the land has re-evolved to the
land. I'm not sure about that though. I
tried to do research on this question
and that is as close as I got to like
somebody who has done one more step. So
obviously the tetropods of the ocean
have never come back out onto land. But
in this case it may be that that
happened with isopods. Wait, how do
snakes get away without eyelids then?
Great question. They shed them. They
shed the protection on top of their eye.
So eyelids are for protecting the eye uh
because you get scratches on the eye.
They build up and they become a problem.
Snakes just get scratches on the eye and
then they shed their skin and they have
a new layer beneath that's fresh and
doesn't have the scratches anymore.
Isn't that cool? I spent five minutes
since watching this video wondering
about the evolution of kidneys in the
renal system. I assume our ability to
process water is related. But what was
the impetus to develop kidneys? I
actually already answered this question
kind of. It was that the first kidneyike
structures were to handle for for
freshwater fish to handle saltwater
environments. I think, correct me if I'm
wrong, but yes, kidneys were very
important. Kidneys were very important
to taking on the land. If everything is
a fish, this brings up the age-old
question. Is shrimps bugs? Yeah, shrimps
is bugs. Shrimps is bugs.
Shrimps, I mean, they're they're
arthropods. Bugs is again, bugs is a
vibes word. Bugs is not actually just a
vibes word. There actually is something
called true bugs, but when you say bugs,
it is implied to not mean true bugs.
That's why there's a phrase true bugs to
just include the true bugs and not all
the other bugs. Is that a baked beans
furby? I don't believe I can't believe
you don't know about my baked beans
Furby. This is Beanie Sanfurbs. He's a
baked bean Furby made by the artist
Sophie G. Stark. You can go and look at
more of Sophie's work and be truly
terrified. If lobe fins are
protoappendages like arms and legs, does
that mean lobe finned fish have butts?
Because legs is butts. Look, butts are
legs. Legs are not butts. You can have a
leg without a butt. You just can't have
a butt without a leg. There are many
organisms that don't have butts but do
have legs. But in the case of butts,
they are a part of the leg. That's my
case. And I just to be clear, this is
not settled science. This is an inside
joke. I haven't watched in a while.
How's the cancer? The cancer is good as
far as I can tell. Been over two years
since I finished treatment and I have
remained in remission. But there is, you
know, they don't call you cured until 5
years. But we're just we're just going
day by day assuming that we're going to
be fine. Do you think somewhere out
there in the world could be an organism
that first evolved in a dry environment?
How alien would that look? Or not in our
planet. Do you think life can only
really begin in water? I'm a chemist and
like life would definitely need to begin
in a liquid. Air is too far apart. Gases
are too far apart and and solids
obviously don't move around. Like life
has to begin in a liquid. And I my my
feeling is that water is by far the best
one. I like I know lots of people who
are smarter than me who are like it
could totally like we we are keeping
open to the reality that it could happen
other ways. Obviously there are many
solvents that chemistry can happen in
and we know in our solar system we have
a a moon a world that has liquid water
cycle that isn't water. It's it's
methane and that's amazing. And so like
water is really good. Water is really
good for chemistry. I like I don't I
don't see it. But I'm just me. I'm just
a guy. Do humans evolve at a slower rate
than other animals? I'd imagine since
evolution takes so long and human lives
are so short, technology is basically
our replacement for evolution. But is it
a mix of both? At this point, humans,
well, what I'll say is to start, humans
evolve much much more quickly than any
animal that has ever existed. Way more
quickly. Look at this. Let me show you
some parts of my body that have very
recently, like within the the last like
50 years, have very recently evolved.
This is an earbud. This is a phone. This
is a a spray bottle that probably is a
little older than 50 years. This is a
tripod. This is a a camera lens. This is
a a yo-yo. Another recent evolution that
is an extension of of the body. We
evolve far more quickly than any animal
that has ever existed that we know of.
Certainly any organism on earth. But
yes, in terms of genetic evolution, we
currently uh like our world is not set
up to have humans evolve genetically
because our world is set up to to
decrease the amount of death as much as
possible and evolution happens mostly
when death happens. Now, there are some
ways that we think that humans are still
evolving. A big one is one that there's
been selective pressure toward the whole
existence of humans, which is the arms
race between the size of the baby's head
and the physiology of the birth. Um, and
uh, it looks like that evolution, you
know, up until fairly recently has been
still happening. The advent of
C-sections, very common C-sections. Uh,
so places where that happens, that means
that that evolutionary pressure no
longer exists. But yeah, uh, in terms of
evolution, we don't have we don't have
like genetic evolution happening at
anywhere near the rate that it used to
happen. But we evolve in other ways
extraordinarily quickly. Like cultural,
technological, all this language that
we're using right now is all uh, you
know, if if that were to evolve
genetically, it would take
billions, billions of years for this
level of information transmission to
evolve genetically. It's also really
interesting that keratin didn't really
adapt into a coating for the body, which
is what happened with arthropods. Uh
they they have developed a coating. What
happened instead was that the dermal
cells adapted into creating
exceptionally strong keratin skeleton
for themselves kind of such that when
they reach the outside and die, their
corpses leave behind a layer of tough
skeletons. Our skin is kind of I this is
why I included this. Our skin is kind of
like a coral reef. It is. I love that.
That's beautiful. And I this isn't
really a question, but that is that is
basically true. And what happens the nit
that I will pick here is that they don't
create an exceptionally strong keratin
skeleton for themselves. They create it
specifically to perpetuate the success
of the colony of cells that is the
organism. So they're not doing it for
themselves. They are murdering
themselves. They kill themselves to
protect the colony so that the colony is
more likely to pass on its genetic
information. Wait, is there really more
oxygen in air than the water? Yes. Um,
so this is a balance between two things.
So, uh, there's way more molecules. The
density of molecules is much higher in
water. Not of air, mostly of water,
mostly of water molecules, but also
other stuff. The density of molecules in
air is much lower. But the percentage of
oxygen in the air is much higher. And
that means that in absolute terms there
is more oxygen in a cubic meter of air.
More oxygen molecules not just density
or anything more absolute number of
molecules in air than absolute number of
oxygen molecules in a cubic meter of
water. There are according to rough
calculations I think around 5.6 * 10 21
oxygen molecules in a liter of air and
about 1.2 2 * 10 20 oxygen molecules in
a liter of ocean water. So that's way
more that's that's an order of magnitude
more than an order of magnitude more in
air than in water. And this is I think
we will end with this one. My favorite
question in the whole list. So if gas
exchange can happen in the gut, does
that mean we have little bits of farts
in our bloodstream? Yes. I had never
thought about this but I thought about
it and it is definitely true. So a
number of the gases that are produced by
microbes in our guts and and also just
the air that we swallow ends up in the
gut. A number of those molecules are
very permeable across that membrane of
the gut. Very water soluble. Hydrogen
sulfide can get in there. Hydrogen,
nitrogen, oxygen, all that stuff can
dissolve in the body and it definitely
like unless somebody can tell me why
this wouldn't happen like this is just a
physical property. Um, like unless there
happens to be more in the blood already
and there's just not like there's that
doesn't make any sense. It would
definitely cross it would definitely
cross that barrier and we would have
those molecules of fart gas in our
blood. Oh wait, I actually know a reason
why this is definitely the case. Using
dissolved gases to diagnose
disease, digestive disease. Analyzing
dissolved gases in the digestive tract
offers a non-invasive way to diagnose
various gastrointestinal conditions.
So I I thought I was talking out of my
butt. Turns out I I knew in my head
somewhere there was the knowledge that
we use dissolved gases in the blood to
actually learn about the digestive system.
system.
I love it. I love it. I love it. I love
it. Thank you so much for uh coming with
me on this journey and learning. If you
want to get this shirt, this is
legitimately your last chance. This has
been such an interesting topic to
discuss. I would love to go deeper. I
can't I know that I can't. I know that
I'm going to move on. I've got lots of
You would not believe my list of video
ideas, but this has been a wonderful
time over the last couple of weeks on
Hank's channel to dive into this. And
it's been nice to get away from some of
the things that I am more frustrated by
and just focus on all the stuff that
we've learned about ourselves and our
world and and how to how to tease out
these bizarre and cool things about it
all. So, thank you for joining me on
that journey. I hope that you have
enjoyed it as much as I have. Wow, I did
a lot of those, but now I have to go.
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