- Game of Thrones star, Hafphor The Mountain Bjornsson recently broke the deadlift world record with a 501 kilogram lift, which is absolutely completely bonkers.

But if he had the lifting power of a leaf cutter ant, he'd be able to lift a medium sized sedan completely over his head and carry it home, not bad.

And if The Mountain had the same relative strength as the Taurus scarab dung beetle, he could pull a fully loaded Boeing 787 Dreamliner.

Compared to us, ants and dung beetles and nature's other miniature weightlifters are special because they pull off their amazing feats of strength without bones.

And it turns out for every species with an internal skeleton like ours, earth is home to around 20 species without one, and many more.

And that got me thinking, why did we end up with our skeletons on the inside instead of the outside?

(classical music tune) Hey, smart people, Joe here, it's time to face the truth.

You're just meat in a sack, tied to a bunch of carefully organized rocks.

And that's basically what it means to be a vertebrate.

And we owe everything that we are, and that we do to our bones.

Skeletons are rigid enough for this and flexible enough for this.

It's said that we're built with 206 bones, but one in eight of us have an extra pair of ribs.

Some people can even have a pair less, and that doesn't count sesamoids and tendons in our hands and feet and elsewhere.

And speaking of feet, you have 52 bones in your feet alone, twice as many as in our spine.

And our hands and feet have more than half the bones in our bodies.

I mean consider that rocks in your fingers, were moved by muscles and nerves to help you click on this video.

The oxygen powering the brain that is watching this is being fed by blood made in your bones.

And you're only even able to hear me thanks to tiny little bones in your ears.

All of this from body parts that are about 70% mineral, made of an inorganic material called hydroxyapatite.

It's combined with a flexible protein called collagen to keep you from shattering.

As a result, the 20 or so pounds in the average body can withstand one ton of compression, and for many of us, they're the last things we'll leave behind.

Bones are pretty awesome and also oss-ome.

That's the Latin word for bone.

Anyway, where did bones come from?

Well that story goes back at least one and a half billion years, which is a weird place to start because animals didn't even exist yet.

But at that moment, violently shifting tectonic plates were washing tons of minerals into the ancient oceans.

The minerals that would one day become skeletons.

Now life stayed pretty squishy for a while.

Early multicellular life depended on the water in which it lived to support those skeleton-less bodies, but then around 558 billion years ago, through a happy accident of evolution, life split in two, and two different skeleton stories began.

On one branch, strange creatures began to develop the first hard protective parts, the precursors of exoskeletons, and this set off an arms race of armor.

Newly shielded organisms might've gotten eaten less.

Maybe they were better protected from the ocean, but partially hard creatures survived more than their squishy friends.

And like I always say, that's what matters in the game of natural selection.

Early exoskeletons got fancier.

We began to see animals with crushing mouthparts, huge pinchers, and full suits of armor.

It was during this period that we see the earliest arthropods, the group that includes modern insects and crustaceans, but on that other branch in squishy tadpole like creatures, something else was happening.

Soft cartilage like back rods began to form in order to provide scaffolding for muscles and for movement.

And on the outside, some of those fishy creatures evolved a cement-like armor.

This was a precursor of bone, and soon this hard stuff formed the basis for new structures like jaws, very big jaws.

Later, this mineral armor was slowly internalized and those early backbones became mineralized.

And together, these became the key parts of the vertebrate skeleton as we know it today.

Over the eons nature has stumbled on many different ways of desquishifying organisms.

There's the lignin and cellulose of plants, the calcium rich shells of mollusks and coral reefs and mineral bones like ours, but insects and crustaceans built exoskeletons made from chains of modified sugars called chitin.

Chitin is molecularly similar to cellulose we find in plants, but it's harder and more stable.

If you were to zoom into a lobster shell on a microscopic scale, you'd see chitin crystals arranged like stacks of plywood and these special nano structure arrangements make chitin exoskeletons incredibly tough for their weight.

And that is why insects are so strong pound for pound or gram for gram.

So if exoskeletons are so strong, then why don't we have them?

Well, like most things in nature, there are trade-offs.

For starters, an armored skeleton makes growing more difficult.

I mean, every time a lobster or cockroach is ready to size up, they have to molt, shedding their old skeleton and leaving them soft and vulnerable for days or weeks while they wait for their new outer shell to harden.

There's also a weight problem.

The strength of ants legs work at their minuscule mass, but scale the ant up to our size and it would be crushed under its own weight.

A few more leg days, you just won't cut it because as a creature gets bigger, its volume and mass increase faster than the tubular strength of its hollow exoskeleton legs.

On the other hand or leg, our internal skeletons provide bigger attachments for muscles than exoskeletons would, and our bones grow with our muscles as we get bigger and stronger, but there's also a trade-off here.

Bulkier vertebrates have to have more massive bones.

An elephant is about 13% bone by weight, not super agile.

A shrew is 4%, and while it's quick, it's pretty easy to squish.

Humans are about eight and a half percent, a compromise between strength and mobility.

If we had more bone to be stronger then we wouldn't move as well.

Another problem is that a human sized ant would suffocate.

Insects don't really have blood.

They have very limited circulatory systems that are filled with a fluid called hemolymph, which is mostly full of metabolic stuff and immune cells.

Insects actually breathe through tiny holes in their exoskeletons to deliver oxygen directly to their tissues through a series of internal tubes.

And the distance oxygen can travel down the tubes depends on its concentration in the air.

During prehistoric times two foot dragonflies did exist because atmospheric oxygen levels were higher.

And plus having all your muscles attached to your outside means that while you're strong, you're not that flexible.

Yeah, let's see you do this, super strong grasshopper.

So a chitin exoskeleton is super strong, but only if you're small.

A human sized ant would be very lethargic, very crumpled, and definitely could not do yoga.

Remember that split that we talked about earlier, one branch led to bugs and exoskeletons, and the other branch eventually led to you and me and every other vertebrates.

And what's crazy to think about is that we are this way because of luck or chance.

Because when our ancestors began to build hard bodies, the only ingredients they had to choose from where what nature provided.

Those shifting tectonic plates, a billion and a half years ago, well, when slabs of rock that make up Earth's crust rubbed together, all the minerals they're made of washed into the sea.

And one of those minerals, calcium carbonate, happens to be a very useful building material.

You see, evolution is a lot like a chef stuck at home during COVID quarantine, by which I mean, you've got to use whatever ingredients you've got around sometimes.

Our very distant relatives were bathed in calcium from those grinding tectonic plates.

And so they use this to build the earliest bone like tissues.

The evolution of bone wasn't some grand a-ha moment in the story of evolution.

It's just one of many such chance events influenced by the environment that set one arm of life on earth on a completely new course.

Invertebrates aren't the only ones who ended up building bodies out of calcium.

Invertebrates from mollusks to coral, to starfish, all use calcium to build their body's support structures, Exoskeleton having animals like insects and other arthropods just went another way.

Building chitin exoskeletons thanks to the chance events of evolution.

And if we played the story of evolution backing in from the beginning,.

perhaps our line will be built differently too.

Which means as we know now, we'd be very smell.

At least we'd have armor, maybe some sweet pinchers, and some horns, But then what would ants look like?

(ominous music) Stay curious.