#3 of 5 short stories on the Origin of Life - The First Language

Translating between languages can have some unexpected results

There is estimated to be an astounding 7,105 languages spoken by various people around the world today. Language is one of those few unique traits that distinguishes humans from other animals and the invention of human language is still a mysterious, yet critical development in the story of human civilization. Each of those languages allow for communication of ideas and gives shape to our thoughts. Of course, moving the ideas crafted in one language over to another between languages can result in an idea being lost in translation, as  use of Google translate can quickly show you - in this example, "I love Sweden" somehow translates as "I love Canada".

But the true first language was not human language, but cellular language. That first language is the universal language of all cellular life today. The time before the first hyperthermophilic cells started running around, the time before the last common ancestor to all known life is fascinating to consider. No one has had a bigger impact on this field of research than the late Carl Woese, who restructured the tree of life to its current 3 Domain format of Bacteria, Archaea and Eukarya. His article, On the Evolutionof Cells is fascinating to read and I recommend it to scientists and non-scientists alike.  

Woese describes a vision of early life, a form of life that would totally fail to pass the cellular/acellular definition of life today.  This pre-cellular life was not a simple, dumbed-down form of the cells we have today, but a complex network of self-repeating processes, a biochemical ecosystem that exchanged packets of information in the form of macromolecules between nodes of activity. We can’t know the exact rules of exchange within that living network, because the exchange of information was so promiscuous,  with biochemical "ideas" passed around so fluidly that there is no discernible pattern of descent left today. But that early biochemical network crossed an important threshold for life, for within that network a language was invented.

The Genetic Code, aka The First Language

That first language is the universal language of all cellular life today. Billions of years after its invention, this language is still spoken by cells in Mycoplasma genitalium, the blue whale, the honey mushroom or a human. There's little divergence from one organism to the next and certainly not at the level of 7,000 languages spoken by people today.  That one molecular language was the symbolic representation of amino acids in 3 letter words of RNA, through a combination of chemical specificity and some arbitrary connections.  The process of using the language is called translation or sometimes casually referred to as The Genetic Code. Some version of the codon table pictured is a staple on molecular biology exams, and in area of study for synthetic biology as we try to develop new ways for using the chemical language that got life started.

Next up is #4 The Singularity (x 3)

Back to #1 The cellular/acellular divide and #2 Magma oceans andmarauding asteroids
 

#2 of 5 short stories on the Origin of Life - Magma oceans and marauding asteroids

2) Magma oceans and marauding asteroids

When we look at the moon, the dark gray "face" that we see is the remnants of a vast magma ocean, so if we could go back in time, there was a time when looking up at the moon you would see a hot, red sea of churning vulcanism. Now things are cooler, both on the Moon and here on Earth.
  

Late Heavy Bombardment as imagined by Timwether
and the evolution of the moon movie from NASA 

The early Earth was hot…or was it? The early earth is quite mysterious. The sun was dimmer at only ~70% of today’s levels, meaning that less energy was coming to the Earth from a colder Sun. Yet the early atmosphere lacked oxygen, and this anaerobic mixture was high in greenhouse gases that would trap in warmth. On top of that, if the moon was born from an early impact 4.5 Ga (4.5 billion years ago), that might have left the Earth surface with a magma ocean, similar to the one the moon had, evident in the dark patterns of lava rock still seen on the Moon today. And a magma ocean, as awesome as that sounds, is totally unsuitable for life. 

So the window for life doesn’t begin until about 4.4 Ga, when the earth cooled enough to allow water vapor to rain down on to the planet and begin to form oceans. The crust of the earth was still undergoing heavy volcanic activity, the magma covered moon was ten times closer, causing the planet to spin faster, such that a day would only last 6 hours. And just to make things even more fun that early period for life to begin was also subject to the Late Heavy Bombardment, a terrific name for a period that saw hundreds of millions of years where the early Earth was subjected to marauding asteroids at a higher frequency of impact than any other time in our planet’s history.

The story of the early Earth is far from complete, and further research will likely continue the debate about how things got started, but life probably got started here while things were still hot and heavy.

Indeed, the earliest cellular life is thought to be super heat-loving hyperthermophiles, that thrive at temperatures that could boil water. Plenty of thermophiles still exist today, and their DNA places them close to the origin of cellular life at ~3.9 Ga. That means that the 500 million year period from 4.4 – 3.9 Ga is where the building blocks for cellular life had to come together -- or arrive from somewhere else -- all while dodging asteroids and magma flows.    

Go on to  #3 The First Language

or back to #1 The Cellular/Acellular Divide