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Thursday, April 29, 2021

Continuous Succession

"For all things are formed by nature to change and be turned and to perish in order that other things in continuous succession may exist.” – Marcus Aurelius

When I was a child my father had a new well dug on the farm. It took a few tries to find the right place, and at one of the failed sites something else was uncovered. From deep under the earth wood was uncovered, from too far down for them to be tree roots. These were the remains of ancient trees long gone. The drill kept going, hundreds of feet down, and suddenly seashells began to appear. Those, the sand and small fossils were from a long-lost ancient sea. What I could not have fathomed then and can barely comprehend now is how very long ago that sea existed.

During the early Paleozoic, 541 to 252 million years ago, what is now Missouri was covered by a warm shallow sea. I can't write 'what is now Missouri' without qualifying that, because the Earth has changed dramatically since that time. Continents have moved and hundreds of feet of soil now cover what existed so long ago. In any case, that sea was home to a menagerie of ancient creatures, including  shelled cephalopods, corals, crinoids, armored fish, and trilobites. Later in the Paleozoic, during the Carboniferous, a wide variety of flora developed on land. That was the period in which oxygen levels were at their highest, sustaining giant insects like dragonflies that could have wingspans of over two feet (more than half a meter). By the end of that period the sea had disappeared from most of the state, although southeastern Missouri was covered with seawater into the early Cenozoic. Since I grew up in northeastern Missouri, the only sea relevant was that of the Paleozoic. 
As I grow older it's easy to become nostalgic about the place where I was born and raised. I spent a lot of my time out in the woods and fields of Missouri, and there's a patch of it around the farm where I grew up that will likely always feel like home. And yet, it has not always been there. I imagine that before the last ice age it looked quite a bit different than it does now, and the same can be said for how it looked prior to European colonization compared to today. Although the country I grew up in has been losing population for over a century, since I was a teenager I've imagined what it would be like for that place to become urbanized. What if those fields and woodlands become housing developments someday, after the population decline reverses?

In truth, the only constant is change. As long ago as 541 million years ago is to us now, the Earth will still exist in another 541 million years. The places that I have known, in Missouri and elsewhere, will be long gone, covered under tons of history. It seems certain that the homo sapiens sapiens subspecies will be long extinct by then, although perhaps I can hope that our passing will not mean the end of the genus Homo. The varieties of creatures that existed in that ancient, shallow sea that existed where we now find Missouri are extinct, but certainly there are species that evolved from them, and then others from those successor species, right down to our time. Humans in the far distant future could be vastly different from us, and if they are spread out in different parts of the solar system and galaxy, they could also be distinct from one another. Unless, of course, we go truly extinct before that.

The world will be different. The continents continue shifting and moving. Species keep evolving. Layer upon layer of new earth is laid down even as mountains are worn down by wind and rain. It is important, I think, to keep some trace of this knowledge in mind in order to put things in their proper perspective. What matters to us intensely now is important because it impacts our lives and those of the world we know. At the same time, will our bones not one day also be fossils found far below earth's surface, telling of a long-forgotten time? There must be this continuous succession, so that new things can come about. That is life, in its truest sense.