Tuesday, February 10, 2009

Genesis or Darwin?

This week is the 200th anniversary of the birth of Charles Darwin, the father of evolutionary science. A long time ago I gave up trying to speak sense to opponents of evolution, because even if I did manage to educate one or two, there seems to be an infinite number behind them ready to take up the torches and pitchforks.   It never ceases to boggle my mind that in America today there are still people who hold the Genesis story as the irrefutable narrative of the detailed story of creation, and refuse to embrace the concept of evolution. Indeed, these people not only reject evolutionary science, they have sought to replace it with a bogus “creation science” which purports to explain the discoveries of evolutionary science within the framework of the Genesis creation story.

This debate started when Charles Darwin published his seminal work the Origin of Species. This work proposed an origin of man quite different from the divine source detailed in Genesis. Christians felt that this was a direct challenge to the very foundation of Christian belief (it was not, but that’s moot). Since Genesis is the first book in the Bible, and the chapters on Adam and Eve are the first part of this book, it’s the one story most universally known by Christians. Most people get bogged down and lose interest in reading the Bible shortly after this point. Most people never finish Genesis, but skip ahead to the “good bits”, thereby losing most of their understanding of the roots of the narrative.

The Creationist View
Facts are facts. No one today can escape the evidence that geology presents us, and the inescapable conclusions which must be derived from it. Creationists seek to explain the evidence at hand within the framework of the Genesis story. In the creationist view, the universe was created in the space of six days approximately 6,000 years ago. This number is derived by extrapolating the dates/ages and genealogies described in the Old Testament. There are some ambiguities regarding the dates derived, but 4000 BCE is a reasonable estimate of the biblical age of the world. In the creationist view, the Earth was created complete. After the creation story, the next significant event was the great flood. According to creationists, the flood engulfed the whole earth, even the highest mountains. Creationists attribute the geological strata as evidence of deposition during the flood. In creation science, evidence that fits their model is trumpeted. Evidence that directly contradicts their model (the majority) is either dismissed as irrelevant, accused of being misinterpreted, or explained as being a red herring placed by the devil to lure people to disbelief. In all cases, the Genesis story trumps everything.

Creation science does not allow for an Earth older than 6,000 years. Some liberal creationists may allow for a few thousand years leeway.

Evolution Science
Creationists take particular pleasure at trying to poke holes in the “Theory of Evolution”. They do so by applying logical fallacies to something they obviously don’t understand. A good deal of the Creationist’s platform is to set evolution up as a straw man. By defining what the theory of evolution is, creationists can knock holes in the theory, and thereby demonstrate that it has no more scholarly authority than creation “science”. Unfortunately, the theory of evolution critiqued by creationists often has little or nothing to do with the science of evolution.

Evolution Science has been known as the “Theory of Evolution” since it was first proposed by Charles Darwin. Creationists gleefully refer to this and point out that “It’s just a theory! Nothing’s been proven!”

Well, there’s also the “theory” of gravity, but if I step off a 100 foot cliff I’ll get just as dead as if it were a proven fact. The evidence subsequent to Charles Darwin is so overwhelming that evolution is considered an established fact. The only theoretical things are certain mechanisms and events that are not fully understood. We have a reasonably good understanding of what happened, when it happened, and a pretty good toolbox of possibilities of how and why it happened. There’s debate among academics of how and why certain events happened, there’s no controversy over the established fact that they did happen.

So let’s take a little refresher into evolution science, so that the young earth crowd can maybe come up to speed on the current model. Hopefully then we can quit recycling the old arguments against evolutionary theory which have been rendered moot by advances in our understanding of evolution.

The original Darwinian model proposed that organisms changed in response to their environment, and that survival of the fittest selected certain traits to dominate over others. This natural selection model was supposed to have produced a steady, gradual drift over time. This seemed to be confirmed by the fossil record, where we found a steady progression of development along family trees, most notably in horses and primitive anthropoids leading up to the human species.

This model had a couple of problems. A favorite question of creationists is that if man evolved from apes, why are there still apes? This is an infantile question, because not even Darwin postulated that the pressures of natural selection would be constant or homogeneous throughout the range of a species’ habitat.

The Darwinian model of continuous gradual evolution was used to justify the fossil evidence of the evolution of homo erectus to Cro-Magnon man. However, the problem with this was the assumption that this evolution would have happened simultaneously across a large geographical area, as homo erectus fossils have been found as far afield from Africa as China and Indonesia. Under this model, Chinese H. Erectus would have evolved into modern Chinese in China, and modern Africans in Africa. No explanation was put forth to explain why such parallel evolution would take place.

Enter genetics. In the 1980’s a study was performed using mitochondrial DNA to try to track genetic divergence within populations. Mitochondrial DNA is the operating machinery within the walls of a cell, and is not recombined during reproduction. Mitochondrial DNA is passed from the mother to the child. Outside of mutations, you have the same mitochondrial DNA as your mother, and her mother, and her mother, etc.   Differences in this DNA are a result of mutation. If you assume a constant, known mutation rate in a general population, you can determine how long it’s been since every member of that population shared a common female ancestor.
The scientists engaged in this study hoped to confirm the Darwinian model, using their current understanding of evolution to predict that the human race would share a common female ancestor about 600,000 years old.

To their surprise, the results yielded a number much more recent that this. The “mitochondrial Eve”, the common female ancestor to the entire human race, lived approximately 140,000 years ago. Advances in DNA sequencing and analysis allowed a similar study to be performed using Y-chromosomes, which are passed from father to son with no contribution from the mother. The age suggested from the drift of Y chromosomes showed that the Y-Chromosome Adam, the common male ancestor to the human race, lived approximately 60,000 years ago. Subsequent studies have allowed forensic geneticists to map out the path of human migration using the frequency of appearance of genetic markers as their guide. See the excellent guide for this on the National Geographic website.

This led to a rethinking of the mechanisms of evolution. Continuous change was replaced with the concept of punctuated equilibrium, and opened up the door to an understanding of the conditions that lead to speciation. Under the new model, evolution takes place in small, isolated populations which are under reproductive stress. If we think of a genetic modification as a drop of food dye and drop it in a test tube, we can quickly disseminate that dye through the contents of the tube for a significant change. If we drop the same dye into a swimming pool, it’s quickly dispersed and has no net effect. The same effect is observable in how a genetic modification is propagated in varying sizes of populations. Also, a genetic modification will only breed true if it offers some reproductive advantage to the holder. In other words, it must allow the holder to have more offspring, or allow its offspring to reach reproductive maturity in greater numbers than those without the modification. This advantage does not have to be terribly significant to allow the new genes to become commonplace in the population. If the population is not under any sort of reproductive stress, there would be no reason for natural selection to favor one gene over another, and no drift would be observable in favor of any particular gene.

The implication of this is that successive waves of hominid species evolved in isolated pockets in Africa, and then migrated out of Africa across southern Asia. They were then replaced by subsequent waves of more advanced hominids. This fits well with the fossil record.

Creationist skeptics aren’t convinced. They want to see the fossil record show the progression in detail. They want to see “the missing link”. Well, the fact is that there are a number of missing links. The fossil evidence we have are snapshots in time, but they clearly demonstrate the progression from primate to modern man. The creationist camp regards the “missing” evidence as an indictment against the evolution model, as if the evidence does not support the conclusion.
In the creationist view, if the evolutionary model were correct, then we should see an unbroken chain of fossils from modern times to the earliest primates. Because we don’t, the creationists insist that the model is flawed. What’s flawed is the creationist understanding of just what a fossil is, and how it comes to be. Fossilization is a very rare event. The probability of any given animal being fossilized after death is vanishingly small. Soil composition, climate, circumstances surrounding the death all play a part in determining if an animal’s remains will become fossilized. The remains must be preserved almost immediately after death, usually by some sort of burial, to prevent scavengers from scattering and consuming them. The soil composition must be relatively pH neutral to prevent the bones from being dissolved. Usually fossilization is associated with flood deposits or sedimentation. Hot, arid conditions may also lead to preservation of the body through mummification before the body is covered and fossilized. Rapid burial due to volcanic action or tarpits is another common precursor to fossilization. Fossilization rarely occurs in forest or steppe settings, where much of the planet’s biodiversity exists. The wonder is not that we have missing links, but that we have any fossil evidence at all. The rarity of fossilization implies a relative abundance of the creatures we find in the fossil record.

Transitional Species
Creationists point out that if the evolutionary model were correct, then why don’t we see any animals in transition from one species to another? Well, the answer’s right in front of our eyes. We just have to define what a transitional species is. A species of animal is defined by being reproductively distinct from other, similar animals. You can’t mate a dog and a cat together and produce offspring. You can’t mate a gorilla and a chimpanzee and produce offspring. These are separate species.

Under the evolution model, when two populations have been separate for a sufficient amount of time, they will have genetically drifted apart to the point where no reproduction is possible. But at what point do you draw the line?

The genus Canis is a relative newcomer on the evolutionary stage. This includes dogs, wolves and coyotes.   While physically and behaviorally distinct, all of these animals can successfully breed with one another and produce viable offspring.

Cats, on the other hand, have been around quite a bit longer. Numerous cats species cannot breed and produce offspring. In a very few cases, the big cats are genetically similar enough that they can produce offspring, but those offspring are sterile. Lions and tigers in captivity have produced sterile offspring. Donkeys and horses may be bred together to produce mules, which are sterile. These are but two examples of species which have drifted enough to speciate but not enough to prevent cross breeding. There’s some speculation that such interbreeding was possible between our ancestors and Neanderthal Man.

Creation science goes to great lengths to explain the strata of the geologic column in terms of the great flood described in Genesis. To a creationist, the successive layers of sedimentary rock are clear evidence of a worldwide deluge. The occasional volcanic deposit that has sedimentary deposits both above and below it are just examples of the upheaval during the flood, according to the creationist. The presence of fossil sea life found in sedimentary formations that are mountains today lead the creationist to conclude that water once covered those mountains. Mountains never change, right?

This explanation is enough to satisfy anyone who casually looks at the strata, but it doesn’t hold up under scrutiny. Paleobiologist Robert Bakker set out to try to identify the climate of the North American plain in Montana during the cretaceous period. One of the things he found embedded in the fossil record were numerous lime balls. These nodules seemed to have been formed underground, just below the surface of the earth. They formed repeatedly, in many different layers of the strata, one on top of the other. Such formations can be found today. On the alluvial plains of India lime is leached out of the soil during the rainy monsoons, and then precipitates into nodules called kunkyars during the long, hot dry season. Since we see similar formations in the cretaceous sediments of Montana, it’s reasonable to assume that 70 million years ago, Montana was subject to a monsoon-like season and a dry season. Such cycles of wet and dry are necessary to form the lime balls which are in the fossil record. There’s no way that such formations could form in a submerged environment. (The Dinosaur Heresies, Robert Bakker, PhD, pp107-110).

Sedimentary rock that’s upthrust into a mountain range will carry with it the fossil evidence of its beginnings at the bottom of an ancient sea. Creationists scoff that a mountain range could rise out of a sea bed. The problem is that the creationist mind can’t wrap itself around the concept of a million years.

We can look at existing earthquake fault regions and draw some conclusions. Let’s take for example, a subduction fault region, which generates a magnitude 6.0 earthquake every hundred years or so. This is not uncommon. A simple search will yield several places on earth today where this would be normal. Now let’s say that each 6.0 earthquake causes a crust displacement of about 6 inches or so. This is also well within the bounds of geologic changes observed in recent history. Now let’s assume this force works over a period of 5 million years. Six inches of displacement every century for 5 million years means the crust will raise 25,000 feet – nearly as high as Mt. Everest! There’s plenty of evidence that the Rocky Mountains were forming 65 million years ago. This is not very much of a stretch at all.

The Flood
The Genesis story of the flood is by no means unique. Every culture around the world has a story of a tremendous flood, which seemed to threaten life itself. Is the Genesis tale a fable, is it the literal truth, or is it an echo of a half-forgotten event in human history?

The Genesis flood simply cannot be the literal truth. It suffices as a fable, but breaks down under scrutiny. One of the many problems with the story is how the animals were distributed after the flood – why there’s the sudden change in zoology along the Wallace Line in the southwest Pacific. Why the primitive marsupial mammals went to colonize Australia. Why did none of the placental animals make it to Australia? Why did birds and lizards make it to New Zealand, but no mammals? The flood story does not explain how freshwater fish -- which would die in salt water -- survived a worldwide deluge, and went on to exclusively populate freshwater ecosystems afterwards. The flood story does not explain the myriad of species of animals, including millions of species of ants and other insects, that exist throughout the world, isolated from Noah’s landing place by prohibitive water barriers even today.

But that doesn’t mean that we dismiss the story completely. We have evidence that the oceans were much lower thousands of years ago than they are today. A stunning testimonial of this is the Cosquer cave in France, where prehistoric cave paintings are protected by a cave entrance that’s under nearly 100 feet of water. In the times when the paintings were made, the sea was 11 miles distant, and 300 feet lower, due to the immense amount of water locked up in continental glaciers more than a mile deep.

Now take a look at a population map of the world today. Even today, the bulk of the human population lives within 300 feet of sea level. For early man, building the first cities near the ocean was a no-brainer. The ocean simply offered too many advantages: cheap, fast and easy trade; a moderated climate; and an abundant supply of food.   It’s a common mistake to think that Cro-Magnon of 10-15,000 years ago was somehow less intelligent that we are today.   A lack of technology does not mean he was any less sophisticated in his thinking and social structures.

How many of us could reproduce even a fraction of our technological foundation, if we were thrust naked into the wilderness? If we suppose that early man formed settlements, even cities, near the sea, and these cities were the repository of knowledge, technology and trade, what would become of them if the sea levels precipitously rose 300 feet? Keep in mind that we can only scuba to about 100 feet deep. Below that the sea floor is mostly an unreachable mystery, and any evidence of ancient civilization has been buried in thousands of years of sediments and coral growth. Civilization was wiped out, whole cities disappeared, and the only people to tell the tale were the refugees and hillbillies, stripped of the veneer of civilization which had been drowned with the cities. Over the generations, the story of the flood that destroyed civilization was told, and embellished to generations that weren’t equipped to understand the story.

And What of Genesis?
The creationist position is that the world was created in six days, as described in Genesis. To accept a different view is heresy. The proponents of this position miss the point. The importance of the creation story of Genesis is not the details of how it happened, but the fundamental morality of the story: God created the universe, God created Man. Man disobeyed God, and separated himself from God in the act. This sets the stage for the rest of the Bible, which is above all the story of the reconciliation between man and God, which culminated in the crucifixion of the Son of God, Jesus Christ.

The details of the story of Genesis are not fundamentally incorrect. They are simply abbreviated, and told within the framework of reference of the target audience: semi-nomadic herders and farmers of the lower Mesopotamian region of 4,000 years ago. These people were not aware of, nor schooled in physics, cosmology, geology, archeology, paleontology, genetics, biology (beyond basic animal husbandry), chemistry, higher mathematics or a myriad of other disciplines which define our view of the world today. To have told a creation story within the framework of modern science to such a people would have done nothing but confuse them and engendered disbelief. It would have masked the real purpose of the story: the morality play of the relationships between God, Man and Creation.

We need not discard the fundamental truths of this morality when we examine creation from the frame of reference of modern science. For someone today to discard the completely overwhelming evidence of the scientific view of the formation of the earth and the evolution of species in favor of a tale told to Mesopotamian herders of 5,000 years ago shows that such a person has more in common with that herder than with a 21st century person with a reasonable education. If it comforts you to discard the evidence before you and cling to the ancient tales, then please do so, but don’t pretend that your tale has exclusive authority of precedence and should be taken seriously by those of us who choose to accept what our eyes and common sense tell us.

I leave it up to you to choose whether to accept the atheist view of evolution or accept some sort of intelligent design rationale. The motive force is irrelevant in the study of evolution and life sciences.   I think pure Creationists miss out by insisting that the literal description in Genesis is the definitive explanation of the origin of the universe. Anyone who studies art or engineering appreciates that the details of a creation reveal insights into how the artist’s mind worked, how the artist interpreted his vision or imagination into a physical reality. Who can look at a DaVinci painting, or a Frank Lloyd Wright design and not marvel at the ingenuity of the creation, how subtle sleights of a curve or corner or texture make a delightfully unexpected contribution to the whole. By examining the brushstrokes of the art, we begin to see into the mind and soul of the artist. How impoverished are the Creationists, who refuse to acknowledge the brushstrokes of God, and appreciate the subtle, mathematical perfection and beauty of his creation by embracing the methods He used. They miss out on a visceral understanding of the genius of the Author of the Universe.