Last week I celebrated Charles Darwin's birthday a day late. This week I will celebrate the end of evolution a billion or two years early. Back in Darwin's day, lots of scientists believed in evolution before it could be proved to be true. Darwin's theory knocked two big holes in our overarching dome of ignorance.
First, he said Nature selected certain traits just as farmers did when breeding livestock. And the reason Nature did this was because the environment kept changing. Darwin was mistaken in some of his pronouncements. No one's perfect, and later scientists have made many corrections and followed the trail way back into antiquity. Way back.
Nature has had all the time in the world to experiment. One writer said that Nature is also shameless, but that depends on what brings you shame. So Nature got started with the Big Bang, 13.8 billion years ago. It was a bloody mess for the next nine billion years. Then things calmed down enough for the earth to form. Just to get a sense of proportion, it would take a person 30 years to count to a billion. So a billion years is plenty of time for life to start.
And it did take about a billion years for the first sign of life to appear on earth. It was a small start, just a single celled bacterium. It gave birth to a second bacterium and on and on. Bacteria doesn't get much respect, but after a half billion years, it invented photosynthesis. That was a big deal, because it allowed oxygen to form. Life jumped beyond the bacteria stage when cells with a nucleus developed.
After three billion years of just bumping into each other, two ambitious cells decided to have sex. As the moralists have warned, all hell broke loose. Over the next billion years, right up to this minute, billions of species have come into existence and 99% of them have gone extinct.
So far Homo sapiens is hanging in there, but we kept a low profile for quite a while. Our first animal ancestor was a sponge. Next we developed nerves and muscles but we were still jellyfish. We branched off into the worm family, then into the starfish clan. We got backbones while swimming with the fish. When some fish crept onto the land we went with them.
We joined the amphibians then the reptiles. When the reptile branch of the family went left, we went right with the mammals. That was a rough spell because the bigger reptiles, the dinosaurs, ate the mammals for lunch. It was best we stayed small as mice, then lemurs for a few million years. When a comet or something wiped out the dinosaurs, we were able to stand up for ourselves. Just 25 million years ago we looked like apes.
The saber tooth tigers were hard on our kind, but fortunately they too went extinct. About 2.5 million years ago a creature looking a bit like us emerged. About 250,000 years ago we had our own species. No more apes. Here's a graphic that shows how long it took to reach our current state of affairs. We could still screw it all up and extinguish ourselves. Then the lemurs would get another shot. I know Sponge Bob is ready.
Great 1501st post! With all our wonderful gifts of imagination, taking perspective is one of our greatest limitations, which reminds me of a pram...
ReplyDeleteACHIEVING PERSPECTIVE
by Pattiann Rogers
Straight up away from this road,
Away from the fitted particles of frost
Coating the hull of each chick pea,
And the stiff archer bug making its way
In the morning dark, toe hair by toe hair,
Up the stem of the trillium,
Straight up through the sky above this road right now,
The galaxies of the Cygnus A cluster
Are colliding with each other in a massive swarm
Of interpenetrating and exploding catastrophes.
I try to remember that.
And even in the gold and purple pretense
Of evening, I make myself remember
That it would take 40,000 years full of gathering
Into leaf and dropping, full of pulp splitting
And the hard wrinkling of seed, of the rising up
Of wood fibers and the disintegration of forests,
Of this lake disappearing completely in the bodies
Of toad slush and duckweed rock,
40,000 years and the fastest thing we own,
To reach the one star nearest to us.
And when you speak to me like this,
I try to remember that the wood and cement walls
Of this room are being swept away now,
Molecule by molecule, in a slow and steady wind,
And nothing at all separates our bodies
From the vast emptiness expanding, and I know
We are sitting in our chairs
Discoursing in the middle of the blackness of space.
And when you look at me
I try to recall that at this moment
Somewhere millions of miles beyond the dimness
Of the sun, the comet Biela, speeding
In its rocks and ices, is just beginning to enter
The widest arc of its elliptical turn.