0:03 Just a little bit ago, about 400 million
0:05 years ago, if you [music] didn't have
0:07 several inches of literal rock covering
0:09 your face, you were basically a mobile
0:12 snack asking to be eaten. And so
0:13 everything back then was covered head to
0:16 toe in rockh hard armor. Fish had
0:18 helmets. Mammals had armor embedded in
0:20 their skin. Even [music] the squids had
0:22 giant cone shells on them. But if you
0:24 look at the ocean today, the heavily
0:26 armored [music] look is almost entirely
0:29 extinct. Aside from a few stubborn
0:31 holdouts like turtles or the occasional
0:33 crab, most of the winners of evolution
0:35 have decided that being soft and squishy
0:37 is actually the superior [music] way to
0:40 live. It seems completely backwards. Why
0:42 would nature spend millions of years
0:44 perfecting the ultimate shield only to
0:46 eventually look at it and decide to just
0:48 delete it all? The most successful
0:50 predators on the planet today, like
0:52 great whites and orcas, are essentially
0:55 walking or swimming around completely
0:58 naked. So why did all animals decide to
1:00 become so vulnerable?
1:02 Well, to understand why nature got rid
1:04 of armor, let's look at the creatures
1:06 who made the most armored era in the
1:08 history of our planet, the placadorms.
1:10 These were the plates skinned fish,
1:12 which essentially means these were fish
1:16 with armor, giant plated armor. And for
1:18 about 50 million years, they were the
1:20 apex predators in the ocean. Their armor
1:23 wasn't just shells or scales. It was
1:25 thick interlocking bone plating on the
1:27 head and torso. Let's take a look at
1:29 Dunlio Ste. It didn't actually have
1:32 teeth. Instead, it had massive razor
1:34 sharp bony plates that acted like
1:37 self-sharpening scissors. It had a bite
1:39 force nearly as strong as a T-Rex. And
1:42 its only purpose was to punch through
1:44 the armor of other armored fish. It was
1:46 an arms race where the only solution to
1:48 someone having a shield was to grow a
1:50 bigger hammer. And back then, having a
1:53 bigger hammer was actually pretty rare.
1:55 Most early predators were, to put it
1:57 lightly, not very good at their jobs.
2:00 They were slow, they were clumsy, and
2:02 their jaws were, well, pathetic. In a
2:04 world where most things are just lazily
2:07 drifting around, armor is the ultimate
2:09 loweffort defense. You don't need to be
2:11 smart, and you definitely don't need to
2:14 be fast. You just need to be hard to
2:15 swallow. For a few hundred million
2:18 years, armor defeated basically every
2:19 problem nature could throw [music] at
2:22 it. Biting, you're biting a rock.
2:24 Crushing, good luck. Piercing with
2:26 claws, you'll break your claws off. It
2:29 was a rational solution for a simpler
2:31 time. The ocean was less of a high-speed
2:32 chase and more of a slow motion
2:35 demolition derby. But as predators
2:37 started getting better, the cost of that
2:39 immortality started to go up. It's not
2:42 like Dunlopas armor was just good for
2:45 its time, either. No lion or tiger today
2:47 would be able to claw through it. It's
2:49 simply way too tough to break through.
2:52 It actually was real armor. But of
2:55 course, Dunlastas didn't last. The lions
2:57 and tigers did. So why would the animal
2:59 with the claws live and the animal with
3:02 the counter to the claws die? Well,
3:04 armor isn't free. It comes with a
3:06 massive biological fee. And for these
3:08 armored fish, the tax they were paying
3:11 was their own ability to move. If you're
3:12 wearing inches of solid bone on your
3:14 face, you aren't exactly doing
3:17 gymnastics. You're heavy, you're stiff,
3:19 and you move about as fast as an
3:21 underwater brick. You are essentially a
3:23 bank vault with a tail. It's great for
3:25 keeping the inside safe, but it's
3:27 [music] terrible for literally
3:30 everything else. As well, armor creates
3:32 a massive energy problem. It's not like
3:34 armor that knights wore where they just
3:36 slapped on some chain mail and a helmet
3:38 and it was kind of heavy. They had to
3:40 create that armor out of something,
3:42 literally their own body. And as you
3:44 might imagine, growing real functional
3:47 bone armor is expensive. To build those
3:49 plates, these fish had to divert a
3:50 massive amount of minerals and calories
3:52 away from their muscles and organs just
3:55 to maintain their shield. But even so,
3:57 creating the wall was worth it until
3:59 nature built a better sledgehammer to
4:01 take those walls down. Eventually,
4:03 predators stopped trying to find a gap
4:05 in the armor and just decided to crush
4:08 it instead. Some fish developed massive
4:09 flattened teeth that worked like
4:11 industrial-grade grinders. They didn't
4:13 need to be fast or graceful. They just
4:15 needed to grab you once and turn your
4:17 [music] expensive bone shield into
4:19 gravel. If your entire survival strategy
4:21 is being hard as a rock, it's a bit of a
4:23 problem when the guy eating you has jaws
4:26 that are now evolved to eat rocks. And
4:28 then things got even weirder. Take a
4:30 look at predatory snails. Instead of
4:32 using brute force, they took the
4:34 high-tech approach. They evolved drills.
4:36 They used a combination of acid and a
4:39 serrated sandpaper tongue to drill a
4:41 perfect tiny hole straight through the
4:43 thicker skulls. It's essentially a
4:45 biological locksmith. All that armor you
4:48 spent millions of calories growing, it's
4:50 now just the sturdy lunchbox that the
4:52 snail has a key to. Once they're inside,
4:54 they just liquefy the squishy bits and
4:57 leave the empty shell behind. This is
4:59 the turning point. When your defense
5:01 doesn't actually defend you anymore,
5:03 it's not a shield. It's just a burden.
5:05 Of course, keep in mind though that
5:07 these snails weren't actually going
5:09 after the giant armored fish or anything
5:11 that was actively fighting back, more
5:13 like simple clam-like animals of the
5:15 time. But they were the first things in
5:16 nature that were hunting by just
5:19 drilling through the shelves. Evolution
5:20 realized the armor was the losing
5:22 investment. The more you put into it,
5:24 the more specialized the predators
5:26 became at breaking it. It's an arms race
5:28 where the cost of the shield eventually
5:30 outweighed the protection it provided.
5:32 And then animals develop the most
5:33 overpowered strategy of all. [music]
5:36 Turning armor is a huge investment for a
5:38 defense that only works if the predator
5:40 is as slow as you are. But predators
5:42 started evolving better ways to move.
5:45 They developed streamlined bodies. They
5:47 stopped trying to outtank each other and
5:49 started trying to outrun each other.
5:51 Suddenly being unkillable didn't matter
5:53 if you were too slow to actually catch
5:55 your dinner. The ocean was shifting from
5:58 a game of defense to a game of agility.
6:00 And in that new world, armor wasn't a
6:02 superpower. It was a literal weight
6:04 dragging you down to the bottom. Being
6:07 unkillable is a consistent drain on your
6:09 body. You're paying for that armor every
6:10 second of the day, whether there's a
6:13 predator around or not. Escape is a pay
6:15 as you go service. You only burn the
6:17 energy when you actually need it, like
6:19 when a shark is behind you. The rest of
6:21 the time, you're light, you're
6:23 efficient, and you're actually getting
6:25 things done. If you can move twice as
6:27 fast as the guy trying to eat you, it
6:29 doesn't matter if your skin is soft.
6:31 He's never going to touch it anyway. And
6:33 once the agility meta took over, the age
6:35 of the biological tank was officially
6:38 over. So where did all that energy go?
6:40 Well, once you cancel the biological
6:42 subscription to your armor, you suddenly
6:44 find yourself with a massive budget
6:46 surplus. So animals put that energy into
6:48 things like better senses to spot danger
6:50 from a mile away or bigger brains to
6:53 outsmart the guy with the big teeth or
6:56 most importantly faster reproduction. In
6:58 the long-term economy of evolution, it's
7:00 actually faster to let a few squishy
7:02 members of your species get eaten than
7:04 it is to spend millions of years trying
7:06 to make one individual indestructible.
7:08 It's pretty brutal, honestly, but it
7:10 works. Instead of survival of the
7:13 tankiest, it becomes survival of so many
7:15 offspring they can't kill all of them.
7:17 Unfortunately for the armored animals,
7:18 armor heavy lineages die off
7:21 disproportionately faster than most
7:23 other animals. It's easier for them to
7:25 go completely extinct. If your entire
7:27 body is encased in bone, your bloodline
7:29 is kind of locked into that shape
7:31 forever. You can't exactly evolve a
7:33 sleeker body or a different tail design
7:35 if your skeleton is on the outside of
7:38 your skin. You're a box and you're going
7:40 to stay a box. This makes armored
7:42 animals incredibly bad at dealing with
7:44 change. When a mass extinction happens
7:46 and over the course of hundreds of
7:48 millions of years, they happen a lot.
7:50 The environment shifts, the food
7:52 disappears, the oxygen levels drop. In
7:55 those moments, being invincible doesn't
7:57 help you. What helps you is being able
7:59 to change your lifestyle. Softbodied
8:01 animals are flexible. They can adapt to
8:03 new niches, shrink their size, or
8:05 develop new ways of moving in just a few
8:07 million years. They're like biological
8:10 clay. Armored lineages, on the other
8:12 hand, are like biological bricks.
8:14 They're specialized for one specific
8:16 world. And as soon as that world
8:18 changes, they're the first ones to go
8:20 extinct. It's why almost every tank from
8:23 the Deonian is gone, while the squishy,
8:24 pathetic looking fish from the same era
8:27 just kept on going. Evolution doesn't
8:29 reward the strongest design. It rewards
8:31 the one that can pivot the fastest. In
8:33 some ways, it's not even survival of the
8:36 animal itself, but variations of that
8:38 animal. Malleable designs are more
8:40 likely to win long-term if adaptations
8:42 are necessary. So, if armor is such a
8:44 bad investment, why do we still have
8:47 things like turtles and crabs? Well,
8:49 they found a loophole. Armor still
8:51 works, but only if you aren't trying to
8:53 be an athlete. Turtles and crabs aren't
8:55 trying to outrun an orca. They live in
8:57 slow niches, habitats where the
8:59 predators are either just as slow as
9:01 they are or simply don't have the tools
9:03 to crack them open. If your shell is
9:05 just slightly tougher than the local
9:07 predators patience, you win. It's a
9:09 specialized low-speed strategy that
9:11 works in the corners of the ocean where
9:14 agility doesn't matter. In reality, the
9:16 crab build is actually one of the best
9:17 builds out there. There's a whole
9:19 phenomenon about why everything seems
9:21 like it's evolving into crabs that I
9:24 made a video on just weeks ago. But if
9:26 you're not a crab, every other creature
9:28 evolved to become fast and vulnerable.
9:29 Take a look at the great white shark.
9:32 It's essentially a giant high-speed
9:35 muscle with teeth. It has zero armor. It
9:36 doesn't even have a skeleton made of
9:38 bone. It's made of lightweight
9:41 cartilage. Its defense is its offense.
9:43 In the modern ocean, the winners are the
9:45 ones who can strike first and leave
9:47 before the counterattack happens. We
9:49 live in the age of the glass cannon. And
9:50 looking at the success of sharks and
9:53 whales, it's clear that being naked was
9:55 the best option. There are still other
9:57 forms of armor today, though, just not
9:59 solid rock armor. Take whales. Instead
10:01 of growing a shell, they grew a
10:04 mattress. Blubber is essentially a foot
10:06 thick layer of dense fat that acts as a
10:08 biological shock absorber. It's the
10:11 ultimate multitasker. It keeps the whale
10:13 warm, stores energy for long trips, and
10:15 happens to be a great way to handle a
10:18 predator. If a shark bites a whale, it
10:20 isn't hitting an organ. It isn't even
10:22 hitting muscle. It's just hitting a
10:24 massive buffer of oil and tissue. The
10:26 whale loses a chunk of fat, but it stays
10:29 perfectly functionable. Its defense by
10:31 just being too much work to kill. Even
10:34 sharks have a secret form of stealth
10:36 armor. Their skin is covered in millions
10:38 of tiny teeth-like scales called dermal
10:41 dentacles. If you rub a shark the wrong
10:43 way, it feels like sandpaper. This is
10:46 armor that actually makes you faster. It
10:48 reduces drag and lets the shark glide
10:50 through the water with almost zero
10:52 resistance. It's not there to stop a
10:54 bite. It's there to make sure the shark
10:56 is the one doing the biting. So, could
10:58 the age of armor ever make a comeback? [music]
10:58 [music]
11:00 It's not like sharks could bite through
11:03 Duncius armor right now anyways. No one
11:04 today is prepared to break through
11:07 rockhard armor because nothing today has
11:10 it. Evolution would recycle ideas that
11:11 worked before if they could work today
11:14 again. But there's one big problem. The
11:17 competition has gotten way too smart. If
11:19 a fish showed up tomorrow with a face
11:21 made of literal granite, an orca
11:22 wouldn't just sit there trying to bite
11:25 it. It would just ram it. Armor protects
11:27 you from a tooth, but it doesn't protect
11:29 you from physics. If you get hit by 6
11:32 tons of apex predator moving at 30 mph,
11:34 it doesn't matter how hard your shell
11:36 is. Your insides are still going to turn
11:38 into a jelly. For armor [music] to
11:40 really win again, the entire world would
11:42 have to slow down. You'd need an
11:44 environment where speed and intelligence
11:46 doesn't matter anymore. Basically, the
11:48 ocean would have to become a slow motion
11:51 demolition derby again. And honestly,
11:54 that doesn't seem likely. Once nature
11:55 figured out how to make brains and
11:58 muscles, it didn't really look back.
12:00 Even ignoring humans, the animals today
12:03 are smart. The naked predators have won
12:04 the arms race. And unless the armored
12:06 animals find a way to overcome Arma's
12:09 weaknesses, they're not coming back. And
12:11 for some reason, I'm okay with that. I'm
12:13 not really looking to get headbutted by
12:15 a sentient rock. Anyway, thank you for
12:17 watching, and I hope you enjoyed the
12:19 video. And if you really enjoyed,
