Romy asks, “What was the starting point of evolution?”
Once upon a time, when the Earth was young, the oceans were littered with a fantastic collection of molecules. Originally it was simple molecules like water and carbon dioxide — debris from the birth of the solar system. But these little building blocks can combine into complex stuff, with a push in the right direction.
Fortunately, the young Earth was a violent and stormy place. Lightning storms and harsh radiation gave these small molecules the jolt they needed to make bigger molecules. Proteins and carbohydrates, sugars and fats, acids and bases and alcohols, all floated around in this “primordial soup.”
Something cool happens when you leave things floating around in a soup of raw materials: a molecule can act like a factory for another type of molecule. How? Well, the rules of chemistry make it so that some chunks of atoms attract other chunks of atoms. Imagine I’m a molecule, and imagine my left foot attracts a chunk named Peanut Butter and my right foot attracts a chunk named Jelly. I’m a walking recipe for PB&Js, and as I waltz through an ocean of ingredients I leave a trail of identical molecules behind me.
Something beautiful has happened here: a totally random process has led to something that seems intentional. Each of these molecules was made by accident, but this “factory” is acting like a diligent craftsman, churning out her product.
This type of thing went on for about a billion years before something incredible happened. One day, completely by accident, a molecule was made that acted like a factory for itself.
You can probably imagine what happened next.
Each new copy started churning out its own stream of copies, colonizing the soup. The molecules felt no thirst for power, but soon enough they dominated the Earth.
This golden age had an end: the replicator was its own downfall. See, no process is perfect, and the recipe wasn’t always followed faithfully. Sometimes a factory would make a dud which couldn’t replicate itself. These poor molecules were no threat to the masterful replicators. But what about when the mistake created a new breed of replicator? Something a bit different, but still able to build an army of itself?
The two breeds kept on blindly printing new copies of themselves, but now their legacies were on the line. If one breed happened to attract materials better, or pump out daughters faster, its numbers would grow. Without realizing it, these molecules were in competition. The more successful replicator would come to dominate the soup.
Of course, it didn’t end there. Mistakes in copying were rare, but had big consequences. More and more breeds of replicators popped up. If a new breed had some advantage over the others, it would quickly climb the ranks. Old breeds lost their edge, and some just couldn’t pull in building blocks like they used to. This led to the world’s first extinctions — the first natural selections.
The winners of this melee had to be very clever to survive. They would be worthy of design awards if they hadn’t been made accidentally!
There were carnivore molecules, which pulled building blocks off of other replicators when materials got scarce. Carpenter molecules built shields to protect themselves from carnivores. Freerider molecules hid behind the shields without carpenters noticing. Repairman molecules hid too, lending a hand when enemies broke through the shield. Architect molecules perfected shield design, messenger molecules eased the teamwork, backstabber molecules mimicked the others while waiting for a moment to strike.
Of course, most new breeds were flops. Like any bad copy, newcomers were almost always worse than the original. These died out quickly. Only the rare mutant who brought something new to the table was able to stick around.
Remember: the replicators didn’t want to build better shields, just like fish don’t want legs and monkeys don’t want mortgages. It’s just that some replicators did build better shields, and they won. Make enough mistakes and you’ll stumble on an innovation.
And four billion years is plenty of time for innovation. The replicators learned to gather in huge teams, dividing up the hard work of survival. They learned photosynthesis, the power to steal energy from the sun. They developed locomotion, letting them find safety and resources in new places. They built brains to plan movement, form habits, make decisions. They invented sensing devices: eyes to turn photons into information about the world, ears to turn air compression into signs of danger. They devised hunger and lust and other emotions to keep their survival machines on the right track.
Using their latest breakthrough, abstract thought, we humans can build powerful tools, communicate complex ideas, cooperate through laws and customs, modify the Earth to our design, build things that outlive us, master the laws of nature, even wonder about our own existence. We’re nature’s greatest feat yet: a pile of stardust that figured out where it came from.
Isn’t it thrilling to think that all this complexity — the cities and jungles, the pixels in this screen and the neurons in your head — is just what happens when you throw some molecules on a rock and let simmer for a few billion years?
More on this: Richard Dawkins, The Selfish Gene (Ch. 2)
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Originally published at milobeckman.com on October 6, 2014.
