Chapter Content
Okay, so like, you know, where do we even begin with the origins of life? It's, like, a massively complex question. So, okay, back in the day, there was this grad student, Stanley Miller, right? He, like, rigged up these, like, two flasks. One had some water in it, you know, to mimic the ancient oceans, and the other had this mixture of gases like, methane, ammonia, and hydrogen sulfide. Basically, they thought it represented the early atmosphere.
And then, get this, he zapped it with some electrical sparks to simulate lightning, right? Like, a few times. And, uh, after a few weeks, the water turned yellowish-green, like, a kind of nutrient-rich broth. It had amino acids, fatty acids, sugars, all sorts of organic compounds, you know? His professor, Harold Urey, was, like, super stoked. He was all like, "I bet that's how God did it!" Haha.
The news back then, it sounded like, you just shake a bottle and bam! Life pops out, right? But, um, reality, you know, surprise surprise, it wasn't that easy. Like, half a century later, and we're still pretty much as far away from creating life as we were back then. Scientists now are pretty sure that, actually, the early atmosphere probably wasn't anything like Miller and Urey's gas mixture. It was probably more like, um, nitrogen and carbon dioxide, which are, like, way less reactive, you know? People have rerun Miller's experiment with those gases, and they barely even get a single basic amino acid.
But, see, even then, the real challenge isn't about making amino acids. It's about proteins. Like, you string amino acids together, you get a protein, right? And we need, like, loads of proteins. Like, nobody really knows for sure, but it could be a million different types of proteins in the human body, each like, a little miracle, you know? And according to probability, they really shouldn't even exist.
To make a protein, you've gotta line up these amino acids – the building blocks of life, as they say – in a very specific order, like spelling a word. Except these amino acid words are, like, crazy long. Like, if you want to spell "collagen," which is a common protein, you only need eight letters. But, to make collagen, you'd have to arrange, like, a thousand and fifty-five amino acid molecules in the exact right order. Okay, But here's the thing, you don't actually *make* collagen, right? It forms on its own, spontaneously, without you doing anything. And, well, that's where the impossibility begins.
Honestly, the probability of 1,055 amino acids lining up to form, like, one collagen molecule is, basically, zero. Like, it's impossible. Just to kind of give you an idea of just how unlikely, imagine a regular Vegas slot machine, but, like, supersized, like, huge! So, like, 90 feet tall so that it has a thousand and fifty-five reels, not just three or four, right? And each reel has twenty symbols, right? One for each common amino acid. Uh, and actually there are twenty-two naturally-occurring amino acids on earth, with some more being found, but only twenty of them are essential to us.
Okay, but so, like, how many times would you have to pull that lever to get all, a thousand and fifty-five, symbols to line up in the perfect order? Like, no number of pulls would do it. Even if you reduced the reels to just 200, which is kind of a more typical number of amino acids in a protein, the chances of all 200 lining up just right is one in ten to the power of minus 260, right? And that number is bigger than the total number of atoms in the universe.
So, long story short, proteins are incredibly complex. Hemoglobin, it's only 146 amino acids long, a baby by protein standards, but even that tiny amount has 10 to the power of 190 ways that that those amino acids can be arranged. And it took some chemist, a guy at Cambridge, like, twenty-three years to figure that out! And, like, just creating a protein by accident would be like, um, like a tornado going through a junkyard and assembling a fully functioning Boeing 747, yeah?
Okay, so, we're talking about, you know, hundreds of thousands, maybe a million different kinds of proteins, each unique, each essential for your health and well-being. But here's the kicker. To be, like, useful, a protein not only needs to have the amino acids in the right order, but it also has to, like, fold itself into a specific shape. And even if it gets that far, it's still useless unless it can replicate itself, and proteins can't. For that, you need DNA. DNA is the replication expert, copies itself in seconds, but, like, that's about it.
So, we're in this paradox. Proteins need DNA, and DNA needs proteins, but neither can exist without the other. Did they just, like, spring into existence at the same time, just to support each other? Oh, my gosh! And DNA, proteins, the other stuff, they need a membrane to keep them all together, yeah?
Atoms or molecules, they don't just, like, spring to life on their own. If you took an atom off of you, it's like a grain of sand, it's dead. Only when lots of atoms get together, in a nutrient-rich cell, then all those different chemicals can do their amazing dance, which we call life. But if you don't have cells, they're just chemicals, if you don't have chemicals, cells are no use. So it begs the question, how did molecular society come about? It's like all the ingredients in your kitchen coming together, just baking themselves into a cake, yeah? And the cake can just divide into more cakes.
So, you know, we call life a miracle and that's an understatement. So what drives this incredible complexity? Well, maybe it isn't, um, you know, isn't quite as miraculous as it first appears, yeah? So, with these proteins, what if the amazing arrangement we see only appeared *after* they formed? Or what if you could control the reels on that slot machine?
Imagine all the stuff that makes a person is put in a container, shake it and a fully-formed person walks out, right? But that is what others, including creationists, argue. They think the proteins were created spontaneously. A protein isn't, and can't be, formed like that. Instead, there is some gradual selection process to make amino acids into lumps.
These chemical reactions are everywhere in life. We can't recreate them in a lab, but the universe can. Things join together to form polymers, sugar molecules form to make starch, and crystals are capable of creating copies of themselves, reacting to the environment, or making complex patterns. Maybe life is inevitable. There's not a lack of spontaneous aggregations. It exists from snowflakes to Saturn's rings.
So, you know, there's nothing actually that special about the chemicals that create us. If you wanted to create more life, you only need carbon, oxygen, hydrogen, and nitrogen, and then a little bit of sulfur, phosphorus, calcium, and iron. Dawkins said there's nothing particularly special about material for creating life and that it's just a collection of molecules, like everything else.
So, it's incredible but not impossible, right? There's still details we can't explain. Everything you read says that water is needed for life, but they forget that dehydration condensation needs to occur to turn monomers into polymers. Scientists agree that this is energetically unfavorable in primal oceans, like putting sugar into water and expecting it to turn into a sugar cube. This shouldn't happen, but nature made it happen anyway.
So, there have been extremely surprising discoveries in the past few decades, one of which is that life happened extremely early, like, 3.85 billion years ago! That's pretty fast. Scientists assume that it's not difficult for bacteria-level life to happen on planets. In 1996, Stephen Jay Gould said that once life could generate, it was chemically inevitable.
Actually, life happened so fast that some suggest that something might've helped, or maybe even gave a lot of help. The idea that life came from space has been around for a while. Back in 1871, Lord Kelvin suggested that meteorites may have carried seeds of life to earth. One Sunday in 1969, thousands of Australians heard a series of rumbles as a fireball went across the sky, and this left a smell that some thought was methylated spirits.
The fireball exploded over Murchison, and rocks rained down. Luckily, nobody was injured. It was a rare type of meteorite. The town was very helpful and found around 90 kilograms of it. Scientists found that the meteorite was 4.5 billion years old and filled with amino acids, and there were also complex sugars.
Since 1969, more carbonaceous chondrites have entered earth. It turns out there are abundant organic compounds in the universe. One view is that if you frequently land on earth, you can get the basic elements of life.
There are two problems with Panspermia, the idea that life came from the outside. The first is that it does not answer how life started; it only passes the responsibility somewhere else. Second, its supporters can get too speculative. One of the people who discovered DNA, Francis Crick, thought that intelligent aliens seeded earth with life. Biochemists easily dismiss those ideas.
Whatever caused life, it only happened one time. This is the most unusual thing we know. Everything traces back to the same original twitch. Sometime in the past, a small sac of chemicals twitched, and that was it.
"Wherever you go in the world, animal, plant, bug, or man, if it has life, it uses the same dictionary and knows the same code." We are all a result of the same trick. That trick has been passed down and, at the end, you can even learn some human genetics to put together a messed-up yeast cell, but the real yeast will make it work as if it were its own. In a very real sense, it is.
The dawn of life sits on a shelf in some geochemist's office. Back in 2001, the geochemist showed me a heavy rock composed of quartz and a gray-green material. It was from Greenland and was 3.85 billion years old.
"We don't know if there are microbes in there, but it comes from the oldest life we've dug up. It could have life." You won't find real microbe fossils because they'd have been baked away. If we smash it up, we'll only find chemical residue of microbes. As for what these organisms looked like, we can only guess.
If you were to go into old rock, the go-to place would be the Australian National University because of Bill Compston. He built the first sensitive high-resolution ion microprobe. This tool was used to determine the decay rate of uranium in tiny minerals called Zircons. These Zircons can survive any process except subduction. Compston's instrument determined these rocks with accuracy. They were first tested in 1982 and determined that the oldest rock ever found was 4.3 billion years old.
She took me down a hall to see Shrimp 2, and someone had been there working since 4 a.m. Rocks need dating, after all. It works by bombarding samples with charged atoms to measure the different levels of lead and uranium to determine age. It takes about 17 minutes to read a Zircon.
The geology yard was a mixture of offices, labs, and instruments. One painting had a geologist's recreation of 3.5-billion-year-old earth. The artist depicted a copper ocean, and the area had rocks with bacteria parasites on it. I asked if this painting was accurate.
"Well, one thought is that it was cool because the sun was weaker. Without the atmosphere, UV rays would tear molecules apart. In that picture, life is almost on the surface, which is a mystery."
"So we don't know what it looked like back then?"
"Yeah."
"But it doesn't look good for life."
"But there must have been things for life, otherwise, we wouldn't be here."
If you walked out of a time machine in the ancient world, you'd go right back in because there'd be no air for us to breathe. The earth was filled with chemicals from sulfuric and hydrochloric acid. There would have been no view. You'd only be able to see due to lightning. It was earth, but not our earth.
For 2 billion years, the only life forms were bacteria. Cyanobacteria created photosynthesis, which is the most important metabolic process of all time, and it was invented by bacteria.
As cyanobacteria increased, the world started to fill with oxygen, and microbes were shocked. Oxygen is basically poisonous, which is why it's able to kill bacteria. We are tolerant to oxygen, but there's a limit. New bacteria that would use oxygen had two benefits. It improved the efficiency of creating energy, and it clobbered its competitors. Some moved to oxygen-free swamps, others moved to places like you and me. Others died.
These cyanobacteria escaped and succeeded. Initially, they combined the iron to create iron oxide and sank to the seafloor. For millions of years, the world turned into rust.
But around 3.5 billion years ago, visible structures came to be. As cyanobacteria completed their chemical process, they started to get sticky. That stickiness stuck to dust and sand and formed strange structures, shallow water stromatolites. Sometimes they looked like cauliflower or shaggy rugs. Stromatolites represent the world's first collaborative project.
For years, scientists learned about them from fossil structures, but in 1961, they found living communities, which was such a surprise that it took years for them to fully realize their discovery. They had wooden boardwalks in Shark Bay where tourists could look at the stromatolites just underwater, and they looked like cow dung. These rocks are filled with life, and some estimate 3.6 billion microbes per rock. These efforts increased oxygen in the atmosphere to 20%, making it easier for future life.
Why did it take so long for life to become complex? For one, the world didn't wait until simple life had filled the atmosphere with oxygen. It took around 2 billion years to get oxygen roughly at current levels. Once conditions were right, a new cell came to be, and that cell had a nucleus and some parts called organelles. The process began when one bacteria was reckless or daring and was either attacked or captured. The bacteria became a mitochondrion, and this let complex life come to be.
Mitochondria dominate oxygen and released energy. Today's life would be simple microbes in mud without them. Mitochondria take up a sand-sized space, are always hungry, and feed off of our nutrients.
Without mitochondria, we wouldn't survive. Even after a billion years, they act like things might not work out and keep their DNA and ribosomes. They reproduce at different times, and they are always ready to pack their bags.
The new type of cell was called eukaryotic, and the old was called prokaryotic. In 1992, a fossil was found, and it was gone for 500 million years.
Earth took its first step toward an interesting planet. Eukaryotic cells are greater than their relatives and can carry more DNA. Life got more complex and created two organisms, the oxygen-rejecters like plants and the oxygen-accepters like us.
They joined to become multicellular organisms. Because of this new invention, we were finally possible.
But before you get too excited, there were still non-animal worlds.