I’ve been working on this sucker a lot, first a couple weeks ago, then got I to play Napa and touch real living humanity and eternity in the wonder of an 8 week old. Been able to stare at a sandstone wall laid down when we were Pangea, and I actually sensed deep-time for a precious moment. I have one more day before deadline and I need to lay this down for a while. Maybe even go to bed early, what a concept.
So 997 words, if evolution interests you, give it a try. If it don’t grab your attention early it’s probably not worth your time. Then again, who knows?
In last month’s celebration of Earth’s Pageant of Evolution I touched on the interplay of geochemistry, tectonics and archaic life. The intimate love-making of geology and biology - to put it poetically, rather than scientifically.Getting back to the science, scientists have learned about the why and how of various ocean bottom geologic structures that provide the catalysts between geochemistry and biochemistry, by helping bind basic molecules into complex organic building blocks of life.
This month to convey the immensity of “Deep Time” I’m scaling down Earth’s 4.6 billion years to 24 hours. A billion years take 5 hours plus change, 3.2 million years tick by every minute. Our human story fits into Earth’s past 4-5 seconds. Imagine that.
Earth was an infant (3-4 minutes) when Theia slammed into her creating our Moon/Earth system. By 3AM baby continents were plowing through the oceans and doing their mountain building; erosion; grinding; pulverizing; redistribution; redigesting; creation drama.
Suggestively the earliest simple celled organisms show up shortly after that. Toughing it out in a very hostile world of raw unfiltered Sun’s rays and energetic-particle bombardment along with Earth’s toxic atmosphere and oceans.
To the rescue - plate tectonics started a cascade of processes - that by around 5 AM induced Earth’s iron core to turn into a dynamo that built a magnetic force field around Earth, thus deflecting those deadly particles. This allowed the slow seepage of geochemically produced oxygen to interact with the sun’s rays, this in turn allowed ozone to form and accumulate, absorbing ever more of those harmful rays.
As Earth’s shielding developed, life figured out how to utilize the tamed sunlight to split water’s H2O bond, using the hydrogen atoms to build sugars while discarding the oxygen. Thus photosynthesis, a potent source of oxygen was born and Earth’s ozone shielding got reinforcing.
Still, the global ocean and atmosphere was a brew of toxins. Though geology and biology was busy cleaning that up, albeit at a glacial pace.
Geology acts very slowly. How slow is slow, you ask? Consider taking a trip around the world moving as fast as your fingernails grow. Worse, upon your arrival you collide and are sent reeling right back across the globe, again and again.
One result was that shallow seas and massive tidal pools existed for immense periods of time, coming and going. While continents were creeping along, archaic microorganisms within those oceans were reproducing every day, when not in hours and minutes.
By afternoon, some simple cells expanded, sequestering their command and control within a reinforced fortress, the nucleus, creating new structures and pathways within the much larger fortified cell membranes.
These cells even took on outside microbes to help with the increasing work load and differentiating duties. Thus Earth’s first Eukaryotes appeared.
In learning about this scientists made a fundamental realization: cell biology and organisms, their development and evolution, cannot be considered without also understanding the environment within which they exist, and to which they must constantly adjust in order to thrive.
So it was, by 3 PM eukaryotes were firmly established, pushing Life’s potential as far as the environment allowed. Then back to biding time, waiting for what came next. Earth continued going through its great geochemical and geophysical convulsions, including continent grinding global ice ages.
By 7 PM ocean chemistry was moderating while free oxygen levels achieved concentrations that allowed those complex eukaryotes to evolve into coordinated communities and then into Earth’s first animals in short order.
But, it was a rough few hours. When communities of critters had a chance to develop and reproduce enough to make a difference, they made a difference alright. They were too bountiful and sucked free oxygen right back out of their environments. Suffocating themselves into extinction, until stromatolites could pump out enough oxygen for another go. One day at a time.
Apparently, living in moderation never was part of Earth’s natural order. Of course, the consequences of this tendency towards excess has always been collapse.
Then around 9 PM and after some 17 hours worth of stage prep; developing various genetic widgets and gadgets, like a Lego set; a few rehearsals; then finally timing lined up and Life took off like unchaperoned teenagers at a springtime full moon dance.
First the Ediacaran “Explosion” lasting around 12 minutes before an extinction event handed Life’s baton over to about 7 minutes worth of the Cambrian “Explosion”. During this third of an hour most to Life’s fundamental body plans appeared, filling every available niche.
The event was even a dilemma for Charles Darwin, since this sudden fossil proliferation was already recognized way back then. Today we understand it as an “eye of the beholder” problem. Looking through the wrong end of the telescope.
160 years of collecting and processing evidence resolves a time span of 60 to 90 millions years worth of biological adventurism. Geologically, it’s shockingly short. Biologically not so much.
Why was the Cambrian radiation so exuberant? Short answer, Earth was ripe and Life was ready. There were no precedents. No competition. No rules. No constraints. Endless amounts of microbial mats on sea floors. Generations ticking away in geologic milliseconds.
As primal animals consumed all those microbial mats and things got grime, competition was born. Then hunting, then ecology evolved and life settled down for the long haul. Well, except for periodic massive catastrophic tectonic upheavals, or the occasional asteroid impact knocking the pins out from under Earth’s biosphere.
When Life has to scramble with new geophysical realities it returns to its ancient genetic toolkit. As the dust settles and critters figured out how to adapt, there were always sudden bursts of amazingly fast (geologically speaking) evolutionary radiation.
Life would then repurpose its genetic heritage into body plans that adapted, survived and thrived in their brave new world. Some say the last couple hours in Earth’s story has only been variations on a theme. But, those must wait for another day.
