During the first half billion years of our planet’s 4.6 billion year existence, the Earth was a very inhospitable place to live.  In fact, the entire solar system was a chaotic collection of irregular protopieces, whirling around the sun in a gigantic Saturn-like ring, smashing into one another with such regularity that the planets remained molten if they remained intact at all. 

It was during this bumper car period of free-wheeling chaos that our moon is thought to have formed – the result of dramatic collision between the early Earth and a Mars-sized object.  It was a glancing blow, but the force of the collision cracked the Earth open like an egg, spilling its contents into space and forming a debris ring of its own.  From this ring of rubble, our moon is thought to have coalesced.

Quite simply, if you ventured outside back then, you’d best not have done it without a helmet. 

Up until that point, it would have been impossible for life to have survived the extremes and uncertainties of such a harsh environment.  But by 4 billion years ago, the Earth had sufficiently swept its orbit clean of planetary chunks, rocks and debris to reduce the number of impacts and collisions to a manageable level.  This allowed the surface to cool and a thin crust to form on the young planet.  As water condensed, it filled in the low spots with a thin veneer of warm, shallow oceans.   

As far back in time as 3.9 billion years ago, (just a few hundred million years after the pummeling stopped and the crust was allowed to form), and certainly by 3.5 billion years ago, there is the undeniable fossil evidence of life on our planet.  Granted, early life consisted of simple unnucleated microbes, cyanobacterias and primitive algaes, but their imprints are unmistakable: great mounds of algae-packed clay called stromatolites and flinty cherts containing microscopic proto-cells.  The “HOW?” and the “WHY?” of life’s beginning and the “WHERE did it come from?” are other questions for other posts at other times.  But that life DID begin very early in Earth’s history is quite certain.

Also early in its development, life made the greatest single discovery in its storied history.  No, not sex, we’re not there yet, it discovered a way to convert sunlight into energy.  And for fully 3 billion years, life went blissfully along – converting carbon dioxide and water into molecular energy bars and releasing minute quantities of oxygen into the water as a by-product.  By 2.5 billion years ago, life had released enough oxygen into the ocean to allow it to begin to escape into the atmosphere where it slowly transformed the atmosphere from a noxious brew of corrosive gases into a mixture more conducive to life: oxygen*, nitrogen and water vapor.  Life had POLLUTED the atmosphere.  It had done so selfishly and completely, if not consciously. And it had changed the environment more fundamentally and more profoundly than anything that man would ever do in the future. This was not the last time that life would change the planet.

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But if life learned anything during those 3 billion years, it was that merely splitting in half solved little to nothing at all.  Its triumphs were halved and its problems were multiplied.

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The basic unit of life is the cell, essentially tiny bags of sea water with a membrane and attitude.  As individual cells became exhausted or were destroyed they needed to be replaced if life was to continue.  Life learned to accomplish this by ripping itself in half to form two identical pieces.  In this way, one became two, two became four, four became eight and those eight quickly became billions.  It was an increase in number but no increase in wisdom.  And so life went on, blissfully, relatively unchanged for millions of billions of trillions of generations.    

But if life learned anything during those 3 billion years, it was that merely splitting in half solved little to nothing at all.  Its triumphs were halved and its problems were multiplied.  For 3 billion years very little changed.  There was minimal change in complexity, minimal development of new features and minimal adaptation to a constantly changing world.  Life maintained itself by sheer simplicity and overwhelming quantity.

Finally, a little over a billion years ago, (quite recent in the larger scheme of things), life at last decided to try something new.  “I’ll tell you what,” life said to itself, “rather than just doing the same thing over and over and over again, I’ll give you some of mine, you give me some of yours, we’ll mix everything up really well and see what happens.  I mean, it can’t hurt.  What’s the worse that could happen?”  

The worst that could have happened was total failure and complete extinction.  But the best that could happen was what ultimately resulted: the invention of sexual recombination.  Suddenly there was new material to work with, new proteins, new chemicals, new appendages, new adaptations, new ideas.  No longer limited to responding to the environment, life went about conquering it.  Cells banded together to form tissues, tissues formed organs, organs begat complex organisms, and organisms formed populations and finally communities.  

Life, which heretofore had been constantly moving away from itself – splitting apart and moving ever outwards, was now forced to move back towards itself – to conjugate, cooperate, recombine and to share.  The invention of sex forced new emotions and traits to evolve: trust, jealousy, sharing, possessiveness, lust, passion, dependence, parenting, remorse, conscience, cunning, desire and protectiveness.    And along with these came the spice of life: wanting, love, competition and heart-break.

Granted, the invention of sex also introduced a whole new raft of problems that required solutions: new plumbing was constructed, delivery and storage systems were developed, incubation and custody rights were thrashed out, division of duties emerged and flamboyant mating behaviors were initiated.  How do you tell one from the other?  Who makes the decisions?  What if I want yours but you don’t want mine?

And WHAT are we going to do about this whole Venus vs. Mars thing???

But steadily, exponentially, spectacularly, life worked out the bugs and embraced sex.  With sex as a vehicle for coming up with new ways to solve old problems, life thrust itself up the evolutionary ladder from those early microbes to increasingly complex beings that conquered the ocean, then the land, then the air, and finally space.  From algal mounds to feathered dinosaurs, eyeballs and astronauts in just over a billion years!

In retrospect, it seems that the logistics part and the plumbing part was the very easiest of all to accomplish.  Life still fumbles with it.  Life always will.  That’s part of life. 

And having established itself, it will take nothing less than renewed cosmic bombardment to remove life from this planet.  Even that may not work.  Life will probably be here in some form until the sun’s light burns out. 

But I suspect that that damn Venus vs. Mars thing will continue to elude us. 

(* I agree, oxygen IS a corrosive gas.)