The evolution of life has seen a significant shift away from heavy biological armor towards agility and speed, as the costs and limitations of armor eventually outweighed its defensive benefits in a changing predatory landscape.
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Just a little bit ago, about 400 million
years ago, if you [music] didn't have
several inches of literal rock covering
your face, you were basically a mobile
snack asking to be eaten. And so
everything back then was covered head to
toe in rockh hard armor. Fish had
helmets. Mammals had armor embedded in
their skin. Even [music] the squids had
giant cone shells on them. But if you
look at the ocean today, the heavily
armored [music] look is almost entirely
extinct. Aside from a few stubborn
holdouts like turtles or the occasional
crab, most of the winners of evolution
have decided that being soft and squishy
is actually the superior [music] way to
live. It seems completely backwards. Why
would nature spend millions of years
perfecting the ultimate shield only to
eventually look at it and decide to just
delete it all? The most successful
predators on the planet today, like
great whites and orcas, are essentially
walking or swimming around completely
naked. So why did all animals decide to
become so vulnerable?
Well, to understand why nature got rid
of armor, let's look at the creatures
who made the most armored era in the
history of our planet, the placadorms.
These were the plates skinned fish,
which essentially means these were fish
with armor, giant plated armor. And for
about 50 million years, they were the
apex predators in the ocean. Their armor
wasn't just shells or scales. It was
thick interlocking bone plating on the
head and torso. Let's take a look at
Dunlio Ste. It didn't actually have
teeth. Instead, it had massive razor
sharp bony plates that acted like
self-sharpening scissors. It had a bite
force nearly as strong as a T-Rex. And
its only purpose was to punch through
the armor of other armored fish. It was
an arms race where the only solution to
someone having a shield was to grow a
bigger hammer. And back then, having a
bigger hammer was actually pretty rare.
Most early predators were, to put it
lightly, not very good at their jobs.
They were slow, they were clumsy, and
their jaws were, well, pathetic. In a
world where most things are just lazily
drifting around, armor is the ultimate
loweffort defense. You don't need to be
smart, and you definitely don't need to
be fast. You just need to be hard to
swallow. For a few hundred million
years, armor defeated basically every
problem nature could throw [music] at
it. Biting, you're biting a rock.
Crushing, good luck. Piercing with
claws, you'll break your claws off. It
was a rational solution for a simpler
time. The ocean was less of a high-speed
chase and more of a slow motion
demolition derby. But as predators
started getting better, the cost of that
immortality started to go up. It's not
like Dunlopas armor was just good for
its time, either. No lion or tiger today
would be able to claw through it. It's
simply way too tough to break through.
It actually was real armor. But of
course, Dunlastas didn't last. The lions
and tigers did. So why would the animal
with the claws live and the animal with
the counter to the claws die? Well,
armor isn't free. It comes with a
massive biological fee. And for these
armored fish, the tax they were paying
was their own ability to move. If you're
wearing inches of solid bone on your
face, you aren't exactly doing
gymnastics. You're heavy, you're stiff,
and you move about as fast as an
underwater brick. You are essentially a
bank vault with a tail. It's great for
keeping the inside safe, but it's
[music] terrible for literally
everything else. As well, armor creates
a massive energy problem. It's not like
armor that knights wore where they just
slapped on some chain mail and a helmet
and it was kind of heavy. They had to
create that armor out of something,
literally their own body. And as you
might imagine, growing real functional
bone armor is expensive. To build those
plates, these fish had to divert a
massive amount of minerals and calories
away from their muscles and organs just
to maintain their shield. But even so,
creating the wall was worth it until
nature built a better sledgehammer to
take those walls down. Eventually,
predators stopped trying to find a gap
in the armor and just decided to crush
it instead. Some fish developed massive
flattened teeth that worked like
industrial-grade grinders. They didn't
need to be fast or graceful. They just
needed to grab you once and turn your
[music] expensive bone shield into
gravel. If your entire survival strategy
is being hard as a rock, it's a bit of a
problem when the guy eating you has jaws
that are now evolved to eat rocks. And
then things got even weirder. Take a
look at predatory snails. Instead of
using brute force, they took the
high-tech approach. They evolved drills.
They used a combination of acid and a
serrated sandpaper tongue to drill a
perfect tiny hole straight through the
thicker skulls. It's essentially a
biological locksmith. All that armor you
spent millions of calories growing, it's
now just the sturdy lunchbox that the
snail has a key to. Once they're inside,
they just liquefy the squishy bits and
leave the empty shell behind. This is
the turning point. When your defense
doesn't actually defend you anymore,
it's not a shield. It's just a burden.
Of course, keep in mind though that
these snails weren't actually going
after the giant armored fish or anything
that was actively fighting back, more
like simple clam-like animals of the
time. But they were the first things in
nature that were hunting by just
drilling through the shelves. Evolution
realized the armor was the losing
investment. The more you put into it,
the more specialized the predators
became at breaking it. It's an arms race
where the cost of the shield eventually
outweighed the protection it provided.
And then animals develop the most
overpowered strategy of all. [music]
Turning armor is a huge investment for a
defense that only works if the predator
is as slow as you are. But predators
started evolving better ways to move.
They developed streamlined bodies. They
stopped trying to outtank each other and
started trying to outrun each other.
Suddenly being unkillable didn't matter
if you were too slow to actually catch
your dinner. The ocean was shifting from
a game of defense to a game of agility.
And in that new world, armor wasn't a
superpower. It was a literal weight
dragging you down to the bottom. Being
unkillable is a consistent drain on your
body. You're paying for that armor every
second of the day, whether there's a
predator around or not. Escape is a pay
as you go service. You only burn the
energy when you actually need it, like
when a shark is behind you. The rest of
the time, you're light, you're
efficient, and you're actually getting
things done. If you can move twice as
fast as the guy trying to eat you, it
doesn't matter if your skin is soft.
He's never going to touch it anyway. And
once the agility meta took over, the age
of the biological tank was officially
over. So where did all that energy go?
Well, once you cancel the biological
subscription to your armor, you suddenly
find yourself with a massive budget
surplus. So animals put that energy into
things like better senses to spot danger
from a mile away or bigger brains to
outsmart the guy with the big teeth or
most importantly faster reproduction. In
the long-term economy of evolution, it's
actually faster to let a few squishy
members of your species get eaten than
it is to spend millions of years trying
to make one individual indestructible.
It's pretty brutal, honestly, but it
works. Instead of survival of the
tankiest, it becomes survival of so many
offspring they can't kill all of them.
Unfortunately for the armored animals,
armor heavy lineages die off
disproportionately faster than most
other animals. It's easier for them to
go completely extinct. If your entire
body is encased in bone, your bloodline
is kind of locked into that shape
forever. You can't exactly evolve a
sleeker body or a different tail design
if your skeleton is on the outside of
your skin. You're a box and you're going
to stay a box. This makes armored
animals incredibly bad at dealing with
change. When a mass extinction happens
and over the course of hundreds of
millions of years, they happen a lot.
The environment shifts, the food
disappears, the oxygen levels drop. In
those moments, being invincible doesn't
help you. What helps you is being able
to change your lifestyle. Softbodied
animals are flexible. They can adapt to
new niches, shrink their size, or
develop new ways of moving in just a few
million years. They're like biological
clay. Armored lineages, on the other
hand, are like biological bricks.
They're specialized for one specific
world. And as soon as that world
changes, they're the first ones to go
extinct. It's why almost every tank from
the Deonian is gone, while the squishy,
pathetic looking fish from the same era
just kept on going. Evolution doesn't
reward the strongest design. It rewards
the one that can pivot the fastest. In
some ways, it's not even survival of the
animal itself, but variations of that
animal. Malleable designs are more
likely to win long-term if adaptations
are necessary. So, if armor is such a
bad investment, why do we still have
things like turtles and crabs? Well,
they found a loophole. Armor still
works, but only if you aren't trying to
be an athlete. Turtles and crabs aren't
trying to outrun an orca. They live in
slow niches, habitats where the
predators are either just as slow as
they are or simply don't have the tools
to crack them open. If your shell is
just slightly tougher than the local
predators patience, you win. It's a
specialized low-speed strategy that
works in the corners of the ocean where
agility doesn't matter. In reality, the
crab build is actually one of the best
builds out there. There's a whole
phenomenon about why everything seems
like it's evolving into crabs that I
made a video on just weeks ago. But if
you're not a crab, every other creature
evolved to become fast and vulnerable.
Take a look at the great white shark.
It's essentially a giant high-speed
muscle with teeth. It has zero armor. It
doesn't even have a skeleton made of
bone. It's made of lightweight
cartilage. Its defense is its offense.
In the modern ocean, the winners are the
ones who can strike first and leave
before the counterattack happens. We
live in the age of the glass cannon. And
looking at the success of sharks and
whales, it's clear that being naked was
the best option. There are still other
forms of armor today, though, just not
solid rock armor. Take whales. Instead
of growing a shell, they grew a
mattress. Blubber is essentially a foot
thick layer of dense fat that acts as a
biological shock absorber. It's the
ultimate multitasker. It keeps the whale
warm, stores energy for long trips, and
happens to be a great way to handle a
predator. If a shark bites a whale, it
isn't hitting an organ. It isn't even
hitting muscle. It's just hitting a
massive buffer of oil and tissue. The
whale loses a chunk of fat, but it stays
perfectly functionable. Its defense by
just being too much work to kill. Even
sharks have a secret form of stealth
armor. Their skin is covered in millions
of tiny teeth-like scales called dermal
dentacles. If you rub a shark the wrong
way, it feels like sandpaper. This is
armor that actually makes you faster. It
reduces drag and lets the shark glide
through the water with almost zero
resistance. It's not there to stop a
bite. It's there to make sure the shark
is the one doing the biting. So, could
the age of armor ever make a comeback? [music]
[music]
It's not like sharks could bite through
Duncius armor right now anyways. No one
today is prepared to break through
rockhard armor because nothing today has
it. Evolution would recycle ideas that
worked before if they could work today
again. But there's one big problem. The
competition has gotten way too smart. If
a fish showed up tomorrow with a face
made of literal granite, an orca
wouldn't just sit there trying to bite
it. It would just ram it. Armor protects
you from a tooth, but it doesn't protect
you from physics. If you get hit by 6
tons of apex predator moving at 30 mph,
it doesn't matter how hard your shell
is. Your insides are still going to turn
into a jelly. For armor [music] to
really win again, the entire world would
have to slow down. You'd need an
environment where speed and intelligence
doesn't matter anymore. Basically, the
ocean would have to become a slow motion
demolition derby again. And honestly,
that doesn't seem likely. Once nature
figured out how to make brains and
muscles, it didn't really look back.
Even ignoring humans, the animals today
are smart. The naked predators have won
the arms race. And unless the armored
animals find a way to overcome Arma's
weaknesses, they're not coming back. And
for some reason, I'm okay with that. I'm
not really looking to get headbutted by
a sentient rock. Anyway, thank you for
watching, and I hope you enjoyed the
video. And if you really enjoyed,
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