Part I: The Mysteries of Ancient Times
Hear my teaching, O my people;(Psalm 78:1-4)
incline your ears to the words of my mouth.
I will open my mouth in a parable;
I will declare the mysteries of ancient times.
That which we have heard and known,
And what our forefathers have told us,
We will not hide from our children.
We will recount to generations to come
The praiseworthy deeds and the power of the LORD,
And the wonderful works he has done.
1. How Did We Get Here?: The Origin(s) of Life on Earth
It is tremendously hard to date when life first arose on Earth. The usual approach is to bracket the origin of life within an age range. The first date is the time before which life was unlikely to exist and the second date is the time at which fossils become unambiguously identifiable as fossils. Both dates have been tricky to pin down. Traditionally, the first date corresponds to the end of the Late Heavy Bombardment, a hypothesized period of extremely intense meteoritic impact primarily inferred from dating of some of the rocks found by the Apollo astronauts, which contain an material that is indicative of asteroid impact. This glass probably forms when an asteroid hits the Moon, vaporizes lunar material, and the material flash-freezes. Some of this material happens to be orange, though not necessarily the impact glass in the older rocks. (I’ve actually seen some of it under the microscope. It may be the most colorful substance on the Moon.)
The story the rocks tell is that ~3.8-3.9 billion years ago, there was some disturbance in the Solar System that sent many comets and/or asteroids spiraling toward the Sun. Although the Sun is big and the Earth and Moon are small, there was apparently enough material spiraling Sunward that the Earth would have experienced the cosmic equivalent of anthropogenic Mutually Assured Destruction every 10-100 years or so. The Moon did not fare much better and some of the largest craters on the Moon probably date from this period. In addition to producing a crater (~ 30 km. or so on the average), such a large impact would have stripped off a bit of the atmosphere, flash-boiled the surface of the ocean within ~100 km., and sent a potentially cell damaging sonic wave over the immediate area. Condensing vaporized rock and other impact fragments also might put particles into the air that would scatter sunlight. Until interest in possible extraterrestrial microbial life grew in recent years, it was generally thought impossible that life could survive in such circumstances, let alone develop. Now, there is less pessimism about the development of life during this entirely too exciting time. Michael Russell, a professor at the Scottish Universities Environmental Research Centre, argues that the most likely origin mechanism would have to have a high probability of repeatability, since life would have been wiped out constantly. However, the nature of the first date does not change too much, since it now marks its “emergence” rather than its origin.
The second date very quickly becomes a matter of opinion? What is a fossil? How can you tell that some structure in a rock is evidence that something was once alive? Well, the oldest strategy is what is called aktualism. You assume that lifeforms in the past might have looked like present organisms or made similar kinds of holes in rocks and draw parallels. Although this particular example of aktualism sounds fairly reasonable, it was quite controversial in the 17th century when Nicholas Steno, a Danish scientist employed by the Grand Duke of Tuscany, argued that the things that looked like seashells in the mountains north of Florence actually were seashells and not random inorganic structures. Of course, aktualism only works if the potential fossil organisms have modern analogs.
One less obvious example of aktualism more relevant to early life is the controversy about the stromatolite. A stromatowhat? Well, stromatolites are structures in layers of sedimentary rock that look like little sets of half-circular layers disturbing the exceptionally regular layers of early sedimentary rock. (I’ll probably mention later why sedimentary rocks tend to have more mottled structures). The original hypothesis was that stromatolites still existed as algae still living in one of the harshest environments on Earth, the intertidal flat, the large piece of shoreline that is alternately covered and uncovered by the tide in areas with a large range between high tide and low tide like the coast of Newfoundland. This particular habitat is a tricky one to occupy, since the chemistry of the water changes radically between high tide and low tide etc. The algae, however, are chemically flexible, just very vulnerable to being eaten, so they do well in intertidal flats but rarely remain as coherent structures on any other surface in modern marine environments. The algae also secrete mucus, like any other typical cluster of cells. This mucus tends to trap clay particles, eventually killing the algae, but forming a new place for their descendants to live on: the graves of their ancestors. Eventually, these algal colonies form mounds that are similar in size and shape to semicircular structures first seen in the rock record about 3.5 billion years ago. Much later, stromatolites actually show evidence of being eaten. Are modern stromatolites the same as ancient stromatolites? Well, the present consensus is that ancient stromatolites differed biologically from modern stromatolites, being cyanobacteria (photosynthesizing bacteria) as opposed to more closely related to the plants like algae. Smaller examples of cyanobacteria fossils are preserved in rocks as old as 3.8 billion years old, suggesting that photosynthesis, a chemical process so complex that humans cannot reproduce it, i.e., use sunlight to split water into hydrogen and oxygen at high efficiency, is at least as ancient as the oldest rocks that possibly could preserve evidence of it.
Rounding out our story of controversial fossils might be the hypothesized biological structures within ALH84001. And by ALH84001, I mean the first meteorite found in the 1984 field season in the Allan Hills area of Antarctica. Or indeed, by ALH84001, I mean a 4.2 billion year old or so chunk of Mars that was knocked off the surface by meteor impact and eventually landed on the Earth. Because no one knows if there is life on Mars or what it might look like, the features of ALH84001 that are proposed to be biological supposedly look like the most primitive microbes on Earth. The more scientifically trained reader might enjoy Allan Treiman’s courageous attempt to keep an open mind about ALH84001 , but the present consensus is that all properties of the meteorite, including its texture, could be produced without biological interference.
Why have we spent so much time talking about dating and early fossils? Wouldn’t the mechanisms of the origin of life be of more interest? Well, they are. In fact, there was heated discussion in the Letters of Science last week of the two major competing hypotheses about what kind of environment produced the first microbes. But it is the dating issue that has stimulated more theological reflection lately.
I really do not know the full story I am about to tell in any detail. I have picked up bits and pieces over the years in my reading and conversing with evolutionary biologists and people who think they have found a proof for the existence of God, but I’ll try to give you a basic idea. In the 1950s, Harold Urey and Stanley Miller at the University of Chicago created organic molecules by shocking a miniature model of the primitive Earth’s atmosphere. This was supposed to simulate lightning on the early Earth. Later research has suggested that the early atmosphere may have been compositionally different (and more or less favorable to organic production) than what was believed in the 1950s. But the chief problem with the Miller-Urey experiment was not its experimental setup but how it has been interpreted in the textbook literature and popular thought. Miller and Urey did not create life. They created organic molecules, the building blocks of life, which at the time seemed fairly close to life. However, organic molecules, we have learned since, are fairly ubiquitous in the Solar System. Meteorites, for instance, contain some fairly sophisticated organic molecules, though of a particular and limited kind. Titan, the chief moon of Saturn, has a much broader organic repertoire in its atmosphere, which has parallels with the atmosphere of the early Earth.
By the early 1980s, researchers realized that the major property that distinguished life from organic molecules was the ability to remember how to manufacture certain kinds of organic molecules that would be useful for the organism. Presently, our own bodies have DNA and RNA to perform that function, but DNA and RNA are far too sophisticated to have been produced by abiotic organic synthesis at random . What was needed was some sort of inorganic substance that could store “information” and eventually make the sophisticated molecules that would replace its function. By the early 1980s, information also was a technical mathematical term, connected with probability, permutation, entropy, and digital computing. Moreover, the analytical techniques of mineralogy had advanced greatly, allowing the structural diversity of naturally occurring inorganic substances to be understood. Soon there developed the Clay Mineral Hypothesis, which proposed that the first life began very much like your grandmother’s wedding china, as polymerized layers of closely bonded silicon and oxygen, filled with magnesium, potassium, iron, aluminum, and water, like a sandwich. Accounting for structural defects and the particular arrangement of metal ions and layers, clays have high potential information content for an inorganic substance. Moreover, clays are ubiquitous, as any mother knows when her small child comes in from playing in the rain. Mud is mostly clay. Clays also typically are a byproduct of volcanically heated water solutions altering volcanic rock, one of the proposed settings for the origin of life.
At this point, I think it would be fair to mention that both the Urey-Miller Experiment and the Clay Mineral Hypothesis had a peculiar attraction to the more religious biologists. The latter especially reminded them of mankind being formed out of the dust of the earth as the second creation account of Genesis implies (and these sentiments have made it into the scientific literature). I think at the back of the mind of many serious Christian scientists is that Moses may have been shown the creation and subsequent events by God and had some trouble comprehending what he was shown, thus any hypothesis that sounds anything like Genesis strengthens one’s faith. Other proponents of the Clay Mineral Hypothesis may like that it is a rehabilitation of the spontaneous generation hypothesis common among the Greeks.
Interest in the Clay Mineral Hypothesis comes and goes. The mineralogists, of course, are fans. Michael Russell (mentioned earlier) seems sold on it. But it serves an illustration of why life is more than organic chemicals. It is the ability to reproduce. It is the ability to resist entropy, i.e., absorption of its own information to the decaying information of the universe. It is the ability to perform the same reaction over and over again, even though the rest of the environment naturally might do something else. In other words, life is coordinated imbalance of the abiotic world. Any hypothesis for the origin of life has to explain why the biotic appears to have a will of its own.
And when photosynthesis developed, life’s role in creating a coordinated chemical imbalance became quite important (wait for the next chapter) The first evidence of this chemical imbalance, the apparently biologically mediated oxidation of iron, is found in rocks in Greenland slightly older (give or take 100 million years) than the first cyanobacteria fossils. In other words, life could not have developed or developed very much before 3.8 billion years, the end of the Late Heavy Bombardment. And yet, life was so chemically sophisticated by the end of the cosmic blitz that it had developed a primitive form of photosynthesis. Is that fast or slow? Well, the first life survived by various simple chemical reactions called oxidation-reduction reactions, typically called chemotrophy. One simple example might be reduction of iron by oxidation of acetate. If you don’t remember your chemistry, it doesn’t matter. The basic reaction is somewhat like spraying rusty metal with WD40, and it produces energy. Chemotrophy, however, doesn’t produce much energy, so the reaction must be repeated at fairly high frequency to keep the organism alive, not unlike a human being trying to survive by eating celery constantly. Worst of all, much chemotrophy results in some sort of solid substance forming in the cell such as iron, which eventually poisons the cell. So chemotrophs must export solids to the environment, which is very energy-intensive.
Despite its disadvantages, chemotrophy is a popular manner of life in hydrothermal vents and other extreme environments. Moreover, the simple chemistry of the chemotrophs appears to be the foundation of the much more sophisticated activity of our own cells and the equally interesting plants. Photosynthesis itself probably began as a modified form of chemotrophy, perhaps as some reactive intermediate absorbed sunlight and split. The hypothesized earliest form of photosynthesis involves the absorption of infrared radiation, just a little redder than the human eye can see. The energy of this absorption was used to oxidize the iron ion Fe2+ to Fe3+, almost always producing iron hydroxide in the presence of water.
In the 1980s, mathematicians became interested in quantitative evolutionary biology. And the evolution of the microbes seemed to be the simplest problem. So these mathematicians tried to produce a mathematical model of how various chemical reactions and structures could evolve, accounting for radiation damage mutations and sex (bacterial sex is a fun subject apparently) etc. The eventual results were that the evolution of the photosynthetic cyanobacteria should have taken billions of years. But I told you earlier that it barely took any time at all. Photosynthesis apparently developed much faster than it should have.
I was in high school when I read the first stories about the emerging intelligent design movement. On one hand, the intelligent design movement stems from the attempts of old earth creationists to rehabilitate their parlor tricks or culture warriors to justify their vision of Biblical morality by giving the intellectual classes a reason to believe in God or something. I once was in charge of catechizing the parents of infants about to be baptized in my parish and the issue of the swift evolution of the bacteria was brought up by one of the parents. So on the other hand, there is an important scientific problem at the heart of intelligent design. The biologists do think carefully about it. Indeed, Joseph Kirschvink, perhaps one of the most gifted thinkers about the origins and ends of life, has speculated that life probably developed in the potentially more favorable environment of Mars.
The theological content of this problem is not quite what William Dembski et al. would like us to believe. The Creeds proclaim a God intimately connected with life, especially through the Person of the Holy Spirit. But while photosynthesis developed relatively quickly, more than a billion years passed before these organisms were dominant. And indeed, at least another billion years passed before the full oxygenic photosynthetic reactions we know today were developed. Before inferring God’s special providence from a potentially fallible mathematical model, let us consider how the Scriptures speak of life and death, particularly Psalm 104, “You send forth your Spirit and they are created…you turn your face away and they fall to dust.” Aristotle, one of the greatest biologists of the ancient world, classified souls in terms of the ends they pursued in unity with their bodies. In more modern terms then, the soul is very much the information content of our body, directing our life processes relative to the abiotic world and hopefully being led to its end in God. Perhaps, the origin of life came when sufficient information content was available to some organic chemicals that the Spirit provided them a nutritive will to sustain them, the basis of the natural law of self-preservation. Perhaps, this consequence was enough to reduce the randomness of evolution, quickly evolving the diverse lifestyles of microbes but was not the specific direction by God to the end of dominant oxygen photosynthesists, for why did it slow? I think I know what answer Dembski would give me, but that will be tackled in my next chapter.
But I don’t think natural law arguments for evolution are theological content either. The question that the origin of life on Earth presents to us is one of our uniqueness. If life is very common, our responsibilities in the wake of Christ become quite complex. The possibility that there are other rational beings out there might direct us to use the resources of the planet as a vehicle for witness, a means of evangelism. But if life is very uncommon and endures with difficulty, we are quite alone and the words of Psalm 95 ring out, “The Earth is the Lord’s, for he made it.” Life on Earth is of such amazing variety and sophistication even in comparison with the inorganic world that there is no possible higher purpose to govern our responsibility to the rest of the world than to preserve this splendid work of God whole and undefiled. It is this principle of uniqueness and the value of the rest of biological life as the masterwork of God’s hands that divides those who believe that they will be held accountable for not exploiting from those who believe they will be held responsible for exploitation of the Earth’s resources.
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