Posts Tagged ‘reproduction’

REVIEWS FROM THE REV: “Evolution in a Toxic World: How Life Responds to Chemical Threats” by Emily Monosson

Sunday, November 11th, 2012

“Evolution in a Toxic World” is, in some ways, a story of the evolution of one toxicologist’s personal and professional evolution in a field that is, by her account, at last merging with the insights available from the field of evolutionary studies.  For it turns out that toxicology has much more to concern itself with than the occasional dramatic case of humans being poisoned by their own chemical creations.  The emerging reality about the interactions of thousands upon thousands of “new” chemical compounds with the evolved biology of every living thing is an area that requires careful study and new ways of defining just what dangers might lurk in our present and future environments (as altered by human activity).

The reality is this: we industrious humans have liberated tons of heavy metals and naturally-occuring materials from the earth through our mining and burning and manufacturing.  Along the way we have invented chemical compounds that have never existed in nature.  It stands to reason that such an environment — changed as it is from the one we evolved in — might produce some surprises in our biology, and this is proving to be the case.

But this case is sometimes subtle and nuanced — not always a tale of deathly poisons, but often of chemicals whose molecular shapes resemble hormones, say, and that fool living cells into taking them up in ways that alters reproductive cycles or DNA.

This book is not alarmist, even if there are alarming revelations as the author takes us along on her own journey into our evolutionary past in order to better understand the task that is before scientists such as her (and humankind).  it is a well-written, cogent and enjoyable book to read, well worth your time if for no other reason than the fact that you have to live your life in this new chemical world we have created.

I highly recommend this book.

t.n.s.r. bob

The rev gives it four Dimetrodons out of four!

SERMON: “The Real Story of Creation” by the not-so-reverend bob

Sunday, April 29th, 2012

There is one, huge, honking reason why we humans have trouble with the idea of evolution, and it is a reason that I think we give scant attention to: it is the fact that we exist.  Because we exist and — more importantly — are conscious of our existence, we can’t help but examine ourselves, find ourselves wonderful, and think that somehow our wonderful existence must — on some level at least — have been the point of everything that has come before us.  We are the reason for, well, life.  “Clearly” we think, “the universe had us in mind from the very start?”

"Why" the reverend asks, "should it make us feel less 'special' to have evolved from earlier life forms?"

This sounds silly and overblown, but is it really?  Don’t we start any consideration of our origins with the premise that we must find a system of “creation” that would clearly lead up to us?  In other words, the process of evolution must be as complicated as we see ourselves to be, which, under the influence of our natural solipsism, means there has to be an intelligence behind it all that is at least as clever as we are (but only more so).  And suddenly, we have replaced the idea of “life” having had us in mind from the start with the idea of The God of the Universe (who, apparently, had nothing better to do with 13.75 billions years of his eternal existence, and decided to run a grand chemical experiment to see if he could turn mass and energy into living hominins who would, occasionally, tell him how great he was).

This is not, I’m afraid, an understatement of the self-centeredness of our species, nor of the absurdity of the proposition of our own divine creation.  The truth is that we can only hold such irrational ideas because we are a natural storytelling (and believing) bunch of hairless apes, and there remains much mutual support for such beliefs among us profoundly-social primates.

But the problem is this: we have built back from the end of the story, assuming that the story began as a tale with us as the ending.  Even more fundamentally, we assume there was a story in the first place.  There wasn’t.  There was (and is, if you want to be absolutely clear about it) only nature.

By nature I mean purely natural forces, and the biological, geologic and meteorological products of those forces.  For there wasn’t even “nature” (at least in the sense that we understand it today) 5 billion years ago.  Only the cosmic beginnings of what would coalesce into our planet.

Seriously.  We now know this.

Our planet formed from dust and debris and matter and gravity and atoms and elements born in other exploding stars (that “made” the stuff our planet is made from).  This is how all of the planets and stars were formed — each of them “local” events (when compared to the vastness of the expanding universe).  And, after untold millions of years of “forming”, the mix of solid crust, liquid water (and the chemical composition of that water), the fact that we had a solid core to produce a magnetic field to hold our atmosphere in place against the forces of solar winds, and time (lots and lots of time — about a billion years after the earth “formed”), something began to stir.  Or maybe not even stir.  In the beginning it was simple photosynthetic bacteria that began to occupy the earth.

And for the next 2 billion years that was it.  That was the only life on the planet.  For 2…billion…years.  What kind of creation story is that?  What kind of intelligence is behind that?  There is the popular (perhaps apocryphal) quote that says “If there is a God, he must be inordinately fond of beetles” (having created hundreds of thousands of species of them).  But perhaps we should change that to God being “Really, really fond of simple photosynthetic bacteria”.

Here’s the rundown of the history of the evolution of life on earth as laid out by Jerry A. Coyne in “Why Evolution is True”:

“If the entire course of evolution were compressed into a single year, the earliest bacteria would appear at the end of March, but we wouldn’t see the first human ancestors until 6 a.m. on December 31.  The golden age of Greece, about 500 BC, would occur just thirty seconds before midnight.”

Most creationists either do not know the evidence for all of this, or are actively resisting it.  I expect more of the latter than the former, for even the ignorance is fed, at some level, by an innate resistance to the notion that we aren’t special in the way we prefer to imagine.

But of course we are special, and by any measurement pretty damn amazing results of a non-random process of selecting random mutations in living, reproducing species.  But we have to be clear that this is what happened.  All it takes, it turns out, for evolution to occur is the presence of DNA that is exchanged and re-combined through (often sexual) reproduction.

Mutations in DNA happen all the time, all over the genome.  But no-one is deciding what mutations will occur.  This is truly a random process — there is no predicting when and where it will happen, nor what the result will be.  Mutations are often the result of biological “copying errors” (take that, perfection of design).  But whatever the cause, those mutations are then expressed in the developing individual, and, once expressed, have entered into the race for survival, living, reproducing, competing and dying on the stage of life where natural selection exerts its unforgiving force on every living thing.

Yet despite what every creationist seems to believe, natural selection is not an intelligence (though it creates an outcome that mimics an intelligence).  It is simply describes the process whereby the reality of climate, food supply, competition for resources, competition for mates, and an animal’s innate suitability for a specific niche in the world place that animal under selective pressure.  Those that are better at surviving tend to survive and pass on their particular set of mutations.  Those that aren’t, don’t.  But conditions are always changing, so today’s winner will not always be the winner.  Dinosaurs were winners for 160 million years, but then they lost.  Big time.  Right now, we’re the winners.  Right now.

Once you take the time to understand what evolution is, and what it is not, the arguments against it are shown to be what they actually are: nothing.  I mean it — there are no valid arguments against evolution.  There are only dodges based in fear, ignorance and credulity (because of the things we want to believe about ourselves).

The reality is that there was never any plan or system in place.  Everything that we see around us is the eventual balance of forces that tends to come about over time.  Earth settled into its shape because of the materials it is made of, which set the levels of gravity where they are.  The dominant cosmic lement of carbon became the building block of all biological life.  Our bodies took the shape they did because of the mix of air we evolved in, and the gravity that gives us weight.  Our eyes evolved to work well in the kind of light we experience, our guts to the kind of food we can eat.

We are constantly taking in nutrients, feeding the bacteria that still makes up half of our cellular weight.  We carry in our DNA huge collections of genes that have been switched-off by random mutations (left in the “off” position by the selective pressures of natural selection).  In many ways, our complex and inspiring bodies are nothing more than the result of a survival “arms race” (as Dawkins put it) that began with the first bacteria competing for a place in the sun.

And DNA, it turns out, builds up entire bodies by completely local actions.  There is no blueprint, but each gene and protein does it’s own little thing and, before long, voila, there is a new living being.

How can this be?  It can be because we evolved from the simplest of life forms that gradually grew more complex (even incorporating other organisms, and turning them to our own use).  Every step of our evolution was built upon the life form we were before every mutation.  Nothing about us ever simply came into being out of “nothing” (that is, ironically, the creationist view of what God is supposed to have done).  We did not go to sleep one night as a bacteria and awake the next morning a fish, or dream our fishy dreams to awake as a primitive ape.  Evolution posits no such thing.  However, the inescapable evidence of our DNA shows the “indelible stamp of our origin” (Darwin’s famous words) — it is a record of the many different animals we were.  There is no other plausible explanation for this than that which evolution supplies.

This drives creationists crazy: it simply cannot be — it sounds too improbable and impossible.  There has to be a plan.

Why?  Who says so?  Who can say to reality “You cannot be thus” or “You must be this”?  No one has that kind of power.  Not you, not me, not the scientist (for this is the implication — that scientists are simply making this stuff up to disprove the God they hate so much).  The scientist reports what is true, what is actual, what is declared by the evidence.  And the evidence tells us that we evolved from bacteria — every one of us representing that unbroken chain of life back to the very beginning.

As Jerry Coyne puts it in “Why Evolution is True” (reviewed this week): “The process is remarkably simple.  It requires only that individuals of a species vary genetically in their ability to survive and reproduce in their environment.  Given this, natural selection — and evolution — are inevitable.”

We humans are a rather, um, late arrival on the scene of life.

Inevitable, yes.  Designed?  No.

But how could an entire human body evolve from a single cell?  As has been pointed out by another: you did it yourself in nine months.

No wonder Darwin said “There is grandeur in this view of life”.  For there is.  But in order to find it, we have to first let go of the diminished, narrow, ignorant view of life as having been created by a divine intelligence.  Then, and only then, will we see, face to face, the true story of our creation.

t.n.s.r. bob