Sunday, February 2, 2014

Anthropogenesis: The Coming Into Being of Humankind (2/2/14)

Anthropogenesis: The Coming Into Being of Humankind

Anthropogenesis:  The Coming Into Being of Humankind
John Shuck

First Presbyterian Church
Elizabethton, Tennessee

February 2, 2014

Genesis and Lloyd Geering
In the day that the Lord God made the earth and the heavens, when no plant of the field was yet in the earth and no herb of the field had yet sprung up—for the Lord God had not caused it to rain upon the earth, and there was no one to till the ground; but a stream would rise from the earth, and water the whole face of the ground— then the Lord God formed man from the dust of the ground, and breathed into his nostrils the breath of life; and the man became a living being.

And the Lord God planted a garden in Eden, in the east; and there he put the man whom he had formed.
Genesis 2:4b-8

Where did we come from?.... What the story so far tells us is that we came from the earth.  However much, during early historical times, our ancestors may have regarded our species as a race apart from all other earthly creatures, or even strangers come to Earth from another world, we can now understand how integral a part we are of the biosphere that has slowly evolved over some four billion years.  We are physically related by varying degrees to all other forms of life on the planet, and if we go far enough back in time we find that we share a common ancestor with every other species that has ever lived.
Lloyd Geering, From the Big Bang to God

Here is a sobering thought:  99% of all the species that have ever lived are extinct.   Consider for a moment the wide variety of life on Earth at this very moment from animal life to plant life to creeping things to pond scum, everything living today.   All of the variety of living species that we see and don’t see all over Earth represents less than 1% of all the species that have ever lived.    

If god cares for every bird and for every flower and for every other creature of its kind, and I am sure it is so, that caring didn’t keep 99% of every species from going extinct.      Yet here you are!  You made the cut!  I keep telling you it is better to be lucky than good.

If we look at human life that is the species homo sapiens from the vantage point of the story of life, there is no reason to think that we will escape the cycle of invention and extinction, birth and death that 99% of all other species who have inhabited Earth have experienced.   Every species has had its moment in the sun. We are having ours.

Again I am reminded of that last haunting line from Mary Oliver’s poem, The Summer Day:

Tell me, what is it you plan to do with your one wild and precious life?

Even as I have said it is better to be lucky than good, there are some good things that individual human beings and the human species as a whole could do at this point in time that would increase our chances of being lucky.   On the other hand, there are things that we can do that will decrease those chances. 

If you are a cigarette smoker you may have heard your doctor or someone tell you that you should give up those cigarettes if you want to live.    No one of course means that if you give up cigarettes you will live forever.  No one means that giving up cigarettes makes you invincible.  You could stop smoking and the very next day get hit by a bus.    But it is true, and studies have shown, that stopping smoking will increase your chances of not contracting an illness that is directly linked to smoking.   

You might get the illness anyway.  That is true.  But your chances of not getting a smoking related illness are improved if you stop smoking or never take it up in the first place.  The question smokers have to ask themselves is whether or not it is worth it.    I think for many, including myself, it was worth giving up the pleasure of smoking and going through the pain of breaking that addiction for the chance of a longer and perhaps healthier life span.

Human beings are clever.  We have been able to extract and produce fossil fuels and we can even boil water by harnessing and controlling nuclear reactions.   Because of our technological wizardry, we have been able to increase the population of the human species to about seven billion today and the vast majority of us live better than royalty of a century ago.    If better is defined as number of comforts, variety of foods consumed, ability to travel, access to information, and so forth, we live like kings.   

But as smoking presents risks to the health of an individual so too does our industrial lifestyle present risks to the health of our species.    As we know the stories of other species overshooting the capacity of their environment to sustain them, human beings are hitting those limits if we have not already passed them.    Human beings are not exempt from the laws of nature.   

We are warned by many daily of the dangers of greenhouse gases, the acidity of the oceans, the draining of aquifers, the demise of marine life, and the effects of pollution and waste.     If we don’t stop, it will kill us.    That does not mean that if we made a 180 degree turn today that we would live forever.   We could get hit by an asteroid or have Yellowstone Park explode and leave us in a volcanic night. Eventually, that will happen.   Eventually the climate will change as it has over the past 2 billion years or so.   

But that could be thousands if not millions of years in the future.  We are playing literally with fire now.   Climate scientists are warning us that positive feedback loops created by the emission of greenhouse gases could make what had taken a thousand years happen in a decade or two. 

The Paleocene-Eocene Thermal Maximum or PETM was the event responsible for mass extinctions 56 million years ago.     It is the most well-documented temperature shift in Earth’s history.   In 2008 geologist Lee Kump of Penn State and his team drilled cores of ice layers in Norway formed during this PETM interval.   These cores detail the rates of change of atmospheric carbon dioxide and climate. Here is the bottom line and I am quoting from Robert Hazen’s book The Story of Earth:

The “PETM—…the most rapid climate disruption in Earth’s history--was triggered by atmospheric changes less than a tenth the intensity of what is happening today. Global changes in atmospheric composition and average temperature that took more than a thousand years during the PETM extinction scenario have been surpassed in just the last hundred years, as humans have burned immense quantities of carbon-rich fuels.”   P. 279-280

We might not think it is worth it to change course. It gives us so much pleasure, it is painful to change, and after all, we will eventually all die anyway.   Yet it seems to me to be worth it to be aware of the dangers of smoking fossil fuels and to make changes now.   We need to make a global decision not to destroy ourselves with weapons of mass destruction.   We need to make a global decision to change our living patterns.  Consciously making the decision as a human race to live within our means is common sense.   I think it is our best chance to avoid a catastrophe of our own making.   

There are so many forces that work against that.   Even so, I don’t give up hope.  I believe that our task is to observe, listen, learn, and say what we see.    What do you plan to do with your one wild and precious life?  A good answer is to say what you see.  And of course, listen.   Tell what is real.  I trust in the hope that if we do that we may reach a tipping point in which what sounded crazy and impossible is actually embraced by humankind as sane and quite possible.       

Pete Seeger added only one line to the scriptural text of Ecclesiastes in his song,Turn, Turn, Turn.  He concluded the song with:

A time of peace, I swear it’s not too late!

And that is why I am devoting this series of sermons to the story of the universe, Earth, life, humankind, and human culture.    I like humans.   I like human cultures. I like the weird things we do.  I like the Super Bowl and Shakespeare.  I like classic rock and classic Bach.  I live with the contradictions as we all do.   I’d like us to be quirky a little bit longer.  We don’t have to be perfect.  We don’t have to live forever, but just enough to squeak by as our ancestors did.    

About 600 million years ago. Earth entered a new eon following the warming of the last global snowball.  It is called the Phanerozoic Era.  Phan means appearance.  It is where we get the word, phantom.   What appeared was life.   Life had been hanging on in its microbial form for 3 billion years or so.    But what is called the Cambrian explosion around 540 million years ago put life on the visible scale.

We can divide the Phanerozoic Era which is from 541 million years ago to today into three eras.   

The Paleozoic era is from 541 million years ago to 252 million years ago.  That is the age of the fishes.  

The Mezozoic era is from 252 million years ago to 66 million years ago.  That is the ages of the reptiles.

Then the Cenozoic era is from 66 million years ago to today.   It is the age of the mammals. 

First the story of land.    At the beginning of the Phanerozoic, 542 million years ago, the continents were broken up and began moving together so at around 300 million years ago they formed the one continent called Pangea.   All of Earth’s land was on one side of the planet.   It remained this way for about 100 million years.  Then around 175 million years ago Pangea started to break up into seven major pieces, the continents we know today.    Continents move at a rate of 1 to ten centimeters per year.   A rule of thumb is about the rate of growth of your fingernails.    Not terribly speedy but give them 175 million years and they can go places.  Eventually they will come together again and form a new huge continent.   

Our beautiful Appalachian mountains, now smooth and green used to be taller than the Himalayas.  They are the product of continents crashing at the speed of a few centimeters per year.  They formed 300 million years ago when Pangea was formed.    They have weathered a bit since then.     They contain coal deposits which are the result of lots of plant life.

Around 580 million years ago life was made of algae and worms and jellyfish type guys.  For about 40 million years these soft animals dominated the oceans.  Then life learned a trick.  About 530 million years ago, many animals learned to build protective shells out of available minerals.   This made them harder to eat.   What started was an arms race of shell building.   Teeth, claws, and spines come on the seen.   This is known as the Cambrian explosion. 

On land, about 475 million years ago, little spores appear on the rocks.   They multiplied for 40 million years then around 430 million years ago more and more land plants begin to appear.    If you were to go back around 400 million years ago, the plant life would be green but fungi and the plants would be stalk-like.  You would find twenty-five foot high fungi trees with little insects and spiderlike animals crawling about.    

There were no leaves on the trees.  Leaves were another evolutionary trick that enabled plants to absorb more sun.  By about 360 million years ago, forests emerged.    Earth was fully emerald green. 

Invertebrates (insects, spiders, and worms) were the first to check out the land. The vertebrates, which were armored fish emerged around 420 million years ago.   They didn’t come on land until around 375 million years ago.    A four-legged walking fish with finlike feet is the oldest known fossil of this adventure to land.      

By around 300 million years ago, Pangea is formed.  You have lush forests.  The atmosphere is 30 percent oxygen.  More than today’s 21 percent.  You have amphibians and massive dragonflies with two feet wingspans.  Life flourishes for tens of millions of years until about 251 million years ago. 

This is the Great Dying.  70% of land species and 96 percent of marine species vanished.   Scientists don’t know exactly why.  Oxygen levels might have dropped, a modest ice age, volcanoes, and even collapse of the ozone layer could have contributed to it.

The Great Dying marks the end of the Paleozoic and the beginning of the Mezozoic.  As beneficiaries of this massive extinction, dinosaurs and reptiles ruled the world from about 230 million years ago until another die-off 66 million years ago.    During the Mezozoic Era flowers began to bloom and the first true mammals emerged.    Pangea broke up during this era and the Atlantic Ocean began to form. 

On one particular day, a day like any other, around 65 million BCE, an asteroid estimated to be six miles in diameter struck the Yucatan Peninsula and a mega-Tsunami swept the globe followed by fires that burned across entire continents darkening Earth and shutting down photosynthesis.    All the dinosaurs except for one lineage, the birds, went extinct.   

Guess who survived?  In addition to the birds, your grandpa and grandma started to sing.    These little rodent-like vertebrates hung out in the dark but within 15 million years of the asteroid strike they had already multiplied and diversified and the early ancestors of whales, bats, horses, and elephants had evolved.   The Cenozoic Era from 65 million years ago to the present is the age of the mammal.  

Monkeys, apes, and Homo sapiens have a common ancestor who lived about 30 million years ago.   The hominids, the primate family who walk erect, emerged around 8 million years ago in Africa.    Meanwhile, climate change that lowered the sea level with the arrival of ice ages allowed land bridges for migrations of all types of mammals. 

Homo habilis, also known as Tim the Tool Man, came out of his garage around 2.5 million years ago after an ice age.    One theory is that cold temperatures favor the survival of infants who stay close to mama.   Also big heads reduce heat loss.  A big head means space for a big brain.  Staying close and spending time with mama and having a big head means you get smart.   Homo habilis or the tool man lived for a million years, finally going extinct about 1.4 million years ago.   Compared to him, we are just babies.

Homo erectus from 1.5 to .5 million years ago was named such because at the time she was the first to walk fully upright.  She also used tools, fire, and possessed some language. 

Homo erectus is the common ancestor of Homo heidelbergensis 500,000 to 230,000 years ago, Homo neanderthalensis 300,000 to 30,000 years ago andHomo sapiens 200,000 years ago to the present.

Many species of the genus homo had their time in the sun.   Finally, Homo sapiens, wise man, so we flatter ourselves, arrived around 200,000 years ago.   We are the last surviving sibling of the genus homo.   

99% percent of all species that ever lived are extinct.   Each mass extinction opens the way for new life.    There have been many twists and turns as Earth is in constant flux.   And life emerges anew and learns its tricks to evolve.   

The show goes on. 
The world is a stage. 
We have our time on it now.  
What part will you play?


No comments:

Post a Comment