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7 - THE SEED OF LIFE
It is therefore believed (among other reasons) that the present earthly atmosphere is not Earth’s original one. Both hydrogen and helium are highly volatile, and their diminished presence in Earth’s atmosphere, as well as its deficiency of “noble” gases such as neon, argon, krypton, and xenon (relative to their cosmic abundance), suggest to scientists that the Earth experienced a “thermal episode” sometime before 3.8 billion years ago—an occurrence with which my readers are familiar by now...
By and large the scientists now believe that Earth’s atmosphere was reconstituted initially from the gases spewed out by the volcanic convulsions of a wounded Earth. As clouds thrown up by these eruptions shielded the Earth and it began to cool, the vaporized water condensed and came down in torrential rains. Oxidation of rocks and minerals provided the first reservoir of higher levels of oxygen on Earth; eventually, plant life added both oxygen and carbon dioxide (CO2) to the atmosphere and started the nitrogen cycle (with the aid of bacteria).
But living cells, even the simplest ones, are made up of complex molecules of various organic compounds, not just of separate chemical elements. How did these molecules come about? Because many of these compounds have been found elsewhere in the Solar System, it has been assumed that they form naturally, given enough time. In 1953 two scientists at the University of Chicago, Harold Urey and Stanley Miller, conducted what has since been called “a most striking experiment.” In a pressure vessel they mixed simple organic molecules of methane, ammonia, hydrogen, and water vapor, dissolved the mixture in water to simulate the primordial watery “soup,” and subjected the mixture to electrical sparks to emulate primordial lightning bolts.
The experiment produced several amino and hydroxy acids—the building blocks of proteins which are essential to living matter. Other researchers later subjected similar mixtures to ultraviolet light, ionizing radiation, or heat to simulate the effects of the Sun’s rays as well as various other types of radiation on the Earth’s primitive atmosphere and murky waters. The results were the same. But it was one thing to show that nature itself could, under certain conditions, come up with life’s building blocks—not just simple but even complex organic compounds; it was another thing to breathe life into the resulting compounds, which remained inert and lifeless in the compression chambers. “Life” is defined as the ability to absorb nutrients (of any kind) and to replicate, not just to exist.
Even the biblical tale of Creation recognizes that when the most complex being on Earth, Man, was shaped out of “clay,” divine intervention was needed to “breathe the spirit/breath of life” into him. Without that, no matter how ingeniously created, he was not yet animate, not yet living.
The murky-waters, or “primordial-soup,”
hypothesis for the origin of life on Earth envisions a multitude of
those earliest organic molecules in the ocean, bumping into each
other as the result of waves, currents, or temperature changes, and
eventually sticking to one another through natural cell attractions
to form cell groupings from which polymers—long chained molecules
that lie at the core of body formation—eventually developed. But
what gave these cells the genetic memory to know, not just how to
combine, but how to replicate, to make the ultimate bodies grow? The
need to involve the genetic code in the transition from inanimate
organic matter to an animate state has led to a “Made-of-Clay”
hypothesis. The launching of this theory is attributed to an announcement in April 1985 by researchers at the Ames Research Center, a NASA facility at Mountainview, California; but in fact the idea that clay on the shores of ancient seas played an important role in the origin of life on Earth was made public at the October 1977 Pacific Conference on Chemistry. There James A. Lawless, who headed a team of researchers at NASA’s Ames facility, reported on experiments in which simple amino acids (the chemical building blocks of proteins) and nucleotides (the chemical building blocks of genes)—assuming they had already developed in the murky “primordial soup” in the sea—began to form into chains when deposited on clays that contained traces of metals such as nickel or zinc, and allowed to dry.
There was more: one scientist, Armin Weiss of the University of Munich, reported experiments in which clay crystals seemed to reproduce themselves from a “parent crystal”—a primitive replication phenomenon; and Graham Cairns-Smith of the University of Glasgow held that the inorganic “proto-organisms” in the clay were involved in “directing” or actually acting as a “template” from which the living organisms eventually evolved.
So the “life-from-clay” theory, in spite of the advances it offered, depended, as the “murky-soup” theory did, on random occurrences—microstructural mistakes here, occasional lightning strikes and collisions of molecules there—to explain the transition from chemical elements to simple organic molecules to complex organic molecules and from inanimate to animate matter.
This news story, and the biblical parallel implicit in it, merited an editorial in the venerable newspaper. Under the headline “Uncommon Clay,” the editorial said:
That the Bible’s been saying so all along, clay being what Genesis meant by the “dust of the ground” that formed man, is obvious. What is not so obvious is how often we have been saying it to one another, and without knowing it.
The conclusion, which appeared to gain support from experiments aimed at searching for “protocells” that were conducted at the Institute for Molecular and Cellular Evolution at the University of Miami, pointed to primitive algae as the first one-celled living creatures on Earth. Still found in ponds and in damp places, algae appear little changed in spite of the passage of billions of years.
Green algae, though without roots, stems, or leaves, began the plant family whose descendants now cover the Earth. It is important to follow the scientific theories of the ensuing evolution of life on Earth in order to grasp the accuracy of the biblical record. For more complex life forms to evolve, oxygen was needed. This oxygen became available only after algae or proto-algae began to spread upon the dry land.
For these green plantlike forms to utilize and process oxygen, they needed an environment of rocks containing iron with which to “bind” the oxygen (otherwise they would have been destroyed by oxidation; free oxygen was still a poison to these life forms). Scientists believe that as such “banded-iron formations’1 sank into ocean bottoms as sediments, the single-celled organisms evolved into multicelled ones in the water. In other words, the covering of the lands with green algae had to precede the emergence of maritime life.
The presence of fruits and seeds as the green growth advanced from grasses to trees also illustrates the evolution from asexual reproduction to sexual reproduction. In this, too, the Bible includes in its scientific account of evolution a step that modern science believes took place, in algae, some two billion years ago. That is when the “green herbage” began to increase the air’s oxygen.
The first maritime vertebrates appeared about 500 million years ago, and land vertebrates followed about 100 million years later, during periods that are regarded by scientists as the transition from the Lower Paleozoic era to the Upper Paleozoic era. When that era ended, about 225 million years ago, (Fig. 45) there were fish in the waters as well as sea plants, and amphibians had made the transition from water to dry land and the plants upon the dry lands attracted the amphibians to evolve into reptiles; today’s crocodiles are a remnant of that evolutionary phase.
Figure 45
The following era, named the Mesozoic (“Middle Life”), embraces the period from about 225 million to 65 million years ago and has often been nicknamed the “Age of the Dinosaurs.” Alongside a variety of amphibians and marine lizards there evolved, away from the oceans and their teeming marine life, two main lines of egg-laying reptilians: those who took to flying and evolved into birds; and those who, in great variety, roamed and dominated the Earth as dinosaurs (“terrible lizards”) (Fig. 46).
The tantalizing reference in these verses of Genesis to the “large reptilians” as a recognition of the dinosaurs cannot be dismissed. The Hebrew term used here, Taninim (plural of Tanin) has been variously translated as “sea serpent,” “sea monsters,” and “crocodile.” To quote the Encyclopaedia Britannica,
Figure 46
The conclusion that by “large Taninim”’ the Bible meant not simply large reptilians but dinosaurs seems plausible—not because the Sumerians had seen dinosaurs, but because Anunnaki scientists had surely figured out the course of evolution on Earth at least as well as twentieth-century scientists have done.
The discovery of fossilized remains of a creature now called Archaeopteryx (“old feather”—Fig. 48a) was deemed to have provided the “missing link” between dinosaurs and birds and gave rise to the theory that the two—dinosaurs and birds—had an early common land ancestor at the beginning of the Triassic period. But even this antedating of the appearance of birds has come into question since additional fossils of Archaeopteryx were discovered in Germany; they indicate that this creature was by and large a fully developed bird (Fig. 48b) that had not evolved from the dinosaurs but rather directly from a much earlier ancestor who had come from the seas.
Figure 48
Whatever the cause, there was an unmistakable end of one evolutionary period and the beginning of another. In the words of Genesis, it was the dawn of the sixth “day.” Modern science calls it the Cenozoic (“current life”) era, when mammals spread across the Earth.
This is how the Bible put it:
Thus did Elohim make all the animals of the land according to their kinds, and all the bovines according to their kinds, and all those that creep upon the earth by their kinds. There is full agreement here between Bible and Science. The conflict between Creationists and Evolutionists reaches its crux in the interpretation of what happened next—the appearance of Man on Earth.
It is a subject that will be dealt with in the next chapter. Here it is important to point out that although one might expect that a primitive or unknowing society, seeing how Man is superior to all other animals, would assume Man to be the oldest creature on Earth and thus the most developed, the wisest.
But the Book of Genesis does not say so at all. On the contrary, it asserts that Man was a latecomer to Earth. We are not the oldest story of evolution but only its last few pages. Modem science agrees.
Up to the point of Man’s creation, then, modern science and ancient knowledge parallel each other. But by charting the course of evolution, modern science has left behind the initial question about the origin of life as distinct from its development and evolution.
For life as we see it on Earth to happen, two basic molecules are necessary: proteins, which perform all the complex metabolic functions of living cells; and nucleic acids, which carry the genetic code and issue the instructions for the cell’s processes. The two kinds of molecules, as the definition itself suggests, function within a unit called a cell—quite a complex organism in itself, which is capable of triggering the replication not only of itself but of the whole animal of which the single cell is but a minuscule component. In order to become proteins, amino acids must form long and complex chains.
In the cell they perform the task according to instructions stored in one nucleic acid (DNA—deoxyribonucleic acid) and transmitted by another nucleic acid (RNA—ribonucleic acid). Could random conditions prevailing on the primordial Earth have caused amino acids to combine into chains? In spite of varied attempts and theories (notable experiments were conducted by Clifford Matthews of the University of Illinois), the pathways sought by the scientists all required more “compressive energy” than would have been available.
The relatively giant molecules of DNA are in the form of two long, twisted strings connected by “rungs” made of four very complex organic compounds (marked on genetic charts by the initials of the names of the compounds, A-G-C-T). These four nucleotides can combine in pairs in sequences of limitless variety and are bound into place (Fig. 49) by sugar compounds alternating with phosphates.
The nucleic acid RNA, no less complex and built of four nucleotides whose initials are A-G-C-U, may contain thousands of combinations. How much time did evolution take on Earth to develop these complex compounds, without which life as we know it would have never evolved?
Figure 49
The fossil remains of algae found in 1977 in South Africa were dated
to 3.1 to 3.4 billion years ago. But while that discovery was of
microscopic, single-celled organisms, other discoveries in 1980 in
western Australia deepened the wonderment. The team, led by J. William Schopf of the University of California at Los Angeles, found fossil remains of organisms that not only were much older—3.5 billion years—but that were multicelled and looked under the microscope like chainlike filaments (Fig. 50). These organisms already possessed both amino acids and complex nucleic acids, the replicating genetic compounds, 3.5 billion years ago; they therefore had to represent, not the beginning of the chain of life on Earth, but an already advanced stage of it.
Figure 50 What these finds had set in motion can be termed the search for the first gene. Increasingly, scientists believe that before algae there were bacteria.
The notion that self-replication on Earth began with bacteria that preceded algae seemed to make sense, since advances in genetics showed that all life on Earth, from the simplest to the most complex, has the same genetic “ingredients” and the same twenty or so basic amino acids. Indeed, much of the early genetic research and development of techniques in genetic engineering were done on the lowly bacterium Escherichia coli (E. coli, for short), which can cause diarrhea in humans and cattle. But even this minuscule, single-celled bacterium that reproduces not sexually but simply by dividing, has almost 4,000 different genes!
Calling such early bacteria “archaeo-bacteria,” a team led by Carl R. Woese of the University of Illinois dated them to a time between 3.5 and 4 billion years ago. Such an age was corroborated in 1984 by finds in an Austrian lake by Hans Fricke of the Max Planck Institute and Karl Stetter of the University of Regensburg (both in West Germany).
They did not attempt, however, to establish how life originated at such a time.
But what gave them their nucleic acids? An avenue of research was opened a few years ago by Leslie Orgel of the Salk Institute in La Jolla, California, when he proposed that the simpler RNA might have preceded the much more complex DNA. Although RNA only transmits the genetic messages contained in the DNA blueprint, other researchers, among them Thomas R. Cech and co-workers at the University of Colorado and Sidney Altman of Yale University concluded that a certain type of RNA could catalyze itself under certain conditions.
All this led to computerized studies of a type of RNA called transfer-RNA undertaken by Manfred Eigen, a Nobel-prize winner. In a paper published in Science (May 12, 1989) he and his colleagues from Germany’s Max Planck Institute reported that by sequencing transfer-RNA backward on the Tree of Life, they found that the genetic code on Earth cannot be older than 3.8 billion years, plus or minus 600 million years.
At that time, Manfred Eigen said, a primordial gene might have appeared “whose message was the biblical injunction ‘Go out into the world, be fruitful and multiply’.” If the leeway, as it appears, had to be on the plus side—i.e., older than 3.8 billion years—“this would be possible only in the case of extraterrestrial origin,” the authors of the learned paper added.
Did our organic matter originate in interstellar space? The infant science of radioastronomy has produced evidence that some of the smaller organic molecules are there. Writing in 1908, Svante Arrhenius (Worlds in the Making) proposed that life-bearing spores were driven to Earth by the pressure of light waves from the star of another planetary system where life had evolved long before it did on Earth. The notion came to be known as “the theory of Panspermia”; it languished on the fringes of accepted science because, at the time, one fossil discovery after another seemed to corroborate the theory of evolution as an unchallenged explanation for the origin of life on Earth.
Whereas our Solar System was formed only some 4.6 billion years ago, other solar systems in the universe may have formed as much as 10 billion years earlier; while the interval between the formation of Earth and the appearance of life on Earth is much too short, there has been as much as six billion years available for the process on other planetary systems.
Their suggestion was therefore that the scientific community “consider a new ‘infective’ theory, namely that a primitive form of life was deliberately planted on Earth by a technologically advanced society on another planet.” Anticipating criticism—which indeed followed—that no living spores could survive the rigors of space, they suggested that the microorganisms were not sent to just drift in space but were placed in a specially designed spaceship with due protection and a life-sustaining environment. In spite of the unquestionable scientific credentials of Crick and Orgel, their theory of Directed Panspermia met with disbelief and even ridicule.
However, more recent scientific advances changed these attitudes; not only because of the narrowing of the Window of Time to a mere couple of hundred million years, almost ruling out the possibility that the essential genetic matter had enough time to evolve here on Earth. The change in opinion was also due to the discovery that of the myriad of amino acids that exist, it is only the same twenty or so that are part of all living organisms on Earth, no matter what these organisms are and when they evolved; and that the same DNA, made up of the same four nucleotides—that and no other—is present in all living things on Earth.
It was therefore that the participants of the landmark eighth Conference on the Origins of Life, held at Berkeley, California, in 1986. could no longer accept the random formation of life inherent in the murky-soup or life-from-clay hypotheses, for according to these theories, a variety of life forms and genetic codes should have arisen. Instead, the consensus was that “all life on Earth, from bacteria to sequoia trees to humans, evolved from a single ancestral cell.”
The research should shift from Earth to Mars, to the Moon, to Saturn’s satellite Titan, it was suggested, because their more pristine environments might have better preserved the traces of the beginnings of life. Such a course of research reflects the acceptance, it must be obvious, of the premise that life is not unique to Earth. The first reason for such a premise is the extensive evidence that organic compounds permeate the Solar System and outer space. The data from interplanetary probes have been reviewed in an earlier chapter; the data indicating life-related elements and compounds in outer space are so voluminous that only a few instances must suffice here. In 1977, for example, an international team of astronomers at the Max Planck Institute discovered water molecules outside our own galaxy.
The density of the water vapor was the same as in Earth’s galaxy, and Otto Hachenberg of the Bonn Institute for Radio Astronomy considered that finding as support for the conclusion that “conditions exist at some other place which, like those on Earth, are suitable for life.” In 1984 scientists at the Goddard Space Center found "a bewildering array of molecules, including the beginning of organic chemistry” in interstellar space. They had discovered “complex molecules composed of the same atoms that make up living tissue,” according to Patrick Thaddeus of the Center’s Institute for Space Studies, and it was,
In 1987, to give one more instance, NASA instruments discovered that exploding stars (supernovas) produced most of the ninety-odd elements, including carbon, that are contained in living organisms on Earth. How did such life-essential compounds, in forms that enabled life to sprout on Earth, arrive on Earth from space, near or distant? Invariably, the celestial emissaries under consideration are comets, meteors, meteorites, and impacting asteroids.
Of particular interest to scientists are meteorites containing carbonaceous chondrites, believed to represent the most primordial planetary matter in the Solar System. One, which fell near Murchison in Victoria, Australia, in 1969, revealed an array of organic compounds, including amino acids and nitrogenous bases that embraced all the compounds involved in DNA. According to Ron Brown of Monash University in Melbourne, researchers have even found “formations in the meteorite reminiscent of a very primitive form of cell structure.”
Writing in Scientific American (August 1983), Roy S. Lewis and Edward Anders concluded that,
Radiocarbon dating has given these meteorites an age of 4.5 to 4.7 billion years; it makes them not only as old as but even older than Earth and establishes their extraterrestrial origin.
In spite of criticism by other scientists, the two have persisted in pressing this theory forward at scientific conferences, in books (Lifecloud and others) and in scholarly publications, offering each time more supportive arguments for the thesis that “about four billion years ago life arrived in a comet.”
In the words of Armand Delsemme of the University of Toledo,
As scientific advances made more sophisticated studies of meteorites, comets, and other celestial objects possible, the results included an even greater array of the compounds essential to life. The new breed of scientists, given the name “Exobiologists,” have even found isotopes and other elements in these celestial bodies that indicate an origin preceding the formation of the Solar System. An extrasolar origin for the life that eventually evolved on Earth has thus become a more acceptable proposition. The argument between the Hoyle-Wickramasinghe team and others has by now shifted its focus to whether the two are right in suggesting that “spores”—actual microorganisms—rather than the antecedent life-forming compounds were delivered to Earth by the cometary/meteoritic impacts.
Foreseeing that Mankind might one day send its “seeds of life” to other worlds, why could it not be that a higher civilization elsewhere had done it to Earth in the distant past?
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