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Welcome to Ph. Deeelicious! I'm your host, Joe,
and today in the primordial kitchen, we're cooking up life. I'm hungry already, let's
get started!
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You can't have life without water.
A touch of carbon!
Mmm, nitrogen!
A little salt of the Earth.
Calcium, strong bones!
Just a touch of phosphorous. That's enough!
What about all those trace elements? A little spice of life! Bam! Bam! BAM! BAM!!
Let's mix that all together…
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Mmm, tangy! We're gonna pour that into a baking dish
pop that baking dish into a 350 degree
oven for about three and a half billion years.
And here's one we prepared earlier!
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That would be pretty cool, but cooking up life is a little more complicated than following
a recipe. And living things don’t come with nice, convenient ingredients labels, like
the packages we buy at the store. But what if they did?
Huh, I didn't know that pineapples have 3-methylthio-prio-pria-pineapple-o-ate
Those chemicals have strange names, but they’re nothing to be afraid of. They’re just the
stuff of life, the molecules that build us, make us move, store energy and information,
even the ones letting you watch and think about this video.
And that’s not even the whole list. If we add in all the nucleic acids, lipids, proteins,
carbohydrates, and also all those minor players like vitamins and cofactors, things like…
I’m not even gonna try that one. Point is, in the recipe for life, the ingredients list
for you and me could fill a whole cookbook.
But what if we put you in a molecular blender, and converted all your complex chemicals into
one human molecule? This is what your chemical formula looked
like at birth:
Now, in ancient times, scholars believed everything in the universe was made of just four elements:
Earth, water, fire, and air. Sorry, Captain Planet.
"You dirty, back-stabbing son of a birch!"
Today we know it’s a little more complicated than that: living things are made up of cells,
cells are made of molecules, they’re made of even smaller atoms… BUT that old idea
turns out to be sort of right.
Altogether, 97% of the mass of all living matter is made of just four chemical elements.
You’re no exception. An average-sized person has 16 kg of carbon inside them, more nitrogen
than in 400 liters of urine. Converted to gas, you hold enough oxygen to fill the volume
of 6 elephants, enough hydrogen to fill the volume of a blue whale.
Add in a few more elements, and that’s nearly ALL of what makes up nearly everything. Different
organisms tweak the percentages a bit, like how our bones are full of calcium, or how
plants use boron in their cell walls, but all in all life seems to work a lot like Taco
Bell, crafting an infinite menu from the same handful of ingredients.
But this barely scratches the surface of the periodic table. Out of 98 naturally-occurring
elements, just over 30 of them are known to be essential to some form of life on Earth.
Why so few? Because not all elements are created equal.
There’s a reason we are “carbon-based life forms” and all of our living chemistry
is “organic”. Many creation stories say life was molded
from clay, from the Earth itself, yet our planet itself doesn’t actually contain much
carbon. But there IS another element in Earth’s crust a thousand times more abundant than
carbon, and which, like carbon, has four outer electrons, and sits just below it on the periodic
table. Why aren’t we silicon-based?
Carbon’s special chemistry lets it bond in a variety of different shapes, building
on itself and other atoms, like nitrogen and sulfur and phosphorous, in long chains and
branches, everything from DNA to amino acids to sugars to fats. Silicon can’t do that.
Slap two oxygens on a carbon, and you get a gas that plants can eat. Combine two oxygens
with silicon, and you get sand. Good luck breathing that. We’ve figured out other
ways to put silicon to good use, but it’s carbon’s variety that led to the variety
of life, and right now, there’s no reason to believe that life in other parts of the
universe would be built on a different backbone.
Rather than dirt, early life was born in ancient seas, which is why the hydrogen and oxygen
from water dominate our ingredient list. When you’re born, you’re more than 75% liquid,
but we all dry out as we get older. Muscle contains more water than fat, our skin is
almost two-thirds liquid, even our bones are more than 30% wet stuff.
In our body, that water is combined with a mix of ions like potassium, sodium, and chloride,
the salts that keep our cells from collapsing, and send electrical signals through our nervous
system. We are are a salty sea, just like the sea we came from.
As we age, changing through the years, our human chemical formula changes with us.
Those rare elements at the bottom of our list, like the iron in our blood, the magnesium
that surrounds our DNA, cobalt in vitamin B12, copper at work in our mitochondria, they
are joined by others that don’t seem to do anything at all. The average adult contains
detectable amounts of 60 elements, mostly just traces of our diet and environment that
have built up over time, remnants of past experiences, like heavy metal memories.
In fact, if you cut off all your toenails and hair, you could even mine gold … not
much, maybe a tiny nugget no bigger than a single grain of salt, worth about a tenth
of a cent. But what about the rest of you? If you isolated all the elements that you’re
made of into their pure form, well… you’d be dead. But if you did this to someone else,
the ingredients for one life would fetch around one to two thousand dollars on the open market.
Of course, you can’t really do that, but it gives us another way to look at life: Everybody’s
worth something, and thanks to inflation, you’ll be even more valuable tomorrow than
you are today. You’re definitely more interesting than
what’s on your label.
Stay curious!