JULY 1, SATURDAY

EVOLUTION

I’ve just finished reading The Rise and Reign of the Mammals by Steve Brusatte and I am still a little stunned as I have been all the way through the book.

He tells the story of the history of mammals from scaly creatures leaving the sea 325 million years ago to mammals as we know them today, including us. But this isn’t just a story about how from insignificant beginnings evolution has finally led to us with our presence on earth. It is more a story about the way evolution works, by chance mutation which leads to adaptation to a changing environment which has resulted in innumerable species all of which either became extinct or were so changed by chance mutation that they were completely transformed.

All mammals have descended from one creature which made its way out of the sea onto land and slowly branched out to thousands of species over millions and millions of years. There were even many, many branches of animals with human like characteristics including walking and running comfortably on two legs with changes in posture that came along with this. Most of these branches became extinct and some interbred with Homo sapiens. And at the end humans have taken over the earth. But we aren’t the only species to take over the earth. Once dinosaurs ruled the earth and all kinds of animals dominated for awhile and then either dwindled or vanished. And all of this happened over millions and millions of years of slow change. Humans have only been here for 200,000 year which in the billions of years of earth’s existence is a very, very short time.

But what stuck me while reading the book was not the facts about an extremely complicated process of unraveling the facts about the history of mammals on earth such as descriptions of teeth and what they tell us about the way species survived, details too numerous to keep track of or even understand. What struck me was the assumptions that we as humans make about ourselves and our individual passage through the world within the context of evolution. What strikes me is how narrow my vision is, how I am almost blind to what it is to be human and my own overestimation of my significance as a human being.

1. Time. One huge lesson is how my perception of time is skewed to thinking only in terms of my own life as being some kind of norm with with everything measured in the immediate time of months and years including my sense even of human history. All that matters is me now with the notion that everything significant before me has been heading toward this moment. This book outlines the millions and millions of years when first one species and then another lived out its existence over millions of years and then vanished, process will continue even after we are gone and when likely humans will be extinct.

2. One earth. This book, without preaching, makes clear that all life on earth is connected and that humans are just one more species, that all forms of life have come about with the same process of evolution. There were many species of human like creatures, homo sapiens were just one. We share 98% of our DNA with chimpanzees. Our fingers are also the five finger wings of a bat, dorsal fin of a whale, the hooves of a horse. We all share the same body, the same organs, but in different shapes. I kind of knew this, but now it smacks me in the face. The same evolutionary process led to all animals and connnects all animals.

3. Fragility. The book makes clear how fragile every form of life on earth has been, needing to constantly adapt through slow chance mutations to a changing environment. My death is part of this fragility, but fragility is all around me in a blind pulsating universe.

4. Complexity. The fact that I can barely follow what he is talking about even when put into simplified popular terms is the first indication of how complicated our physical bodies are with our enlarged complicated brain being the most complicated organ of all. Like a complete dodo (really) I somehow take my body for granted when every organ is part of this blind process of adaptation. I inhabit this body with almost no clue about what it is and how it came to be.

5. Ignorance. What strikes me again and again is how recent some of these overwhelming discoveries about evolution from the Big Bang on have been. An overwhelming number of them have been in my life time, so many of the biggest discoveries such as the significance of DNA have been in the last 25 years, many of these discoveries in the last five years. As we have created our very complicated cultures and our assumptions about what it is to be human, cultures that give us our identity, we have done so in ignorance or our chance place in the cosmos.