A Brief History of Creation (27 page)

Three years later, with Hall's recommendation, Walcott was appointed to the newly formed US Geological Survey (USGS). Soon he was heading west to explore one of the greatest natural wonders of North America, the Grand Canyon, about which remarkably little was then known.

Charles Doolittle Walcott at the Grand Canyon.

The Grand Canyon turned out to be a paleontologist's dream. For seventeen million years, the Colorado River had chiseled a course deep into the hard, rocky ground, leaving a majestic gash 277 miles long and over a mile deep. Though it is second in size to Nepal's Kali Gandaki Gorge, the Grand Canyon's bareness made it unrivaled in potential for study by a paleontologist like Walcott. Its features were not hidden by rich vegetation as they were in the Kali Gandaki, or even the smaller foothills of England and Scotland that had been explored by most of the century's greatest fossil hunters. Its walls resembled the clean, layered faces of a canal, except it was a canal that cut a mile beneath the surface and through two billion years of rock formations.

The leader of the USGS expedition, John Wesley Powell, realized the Grand Canyon's potential as an archaeological site. He put Walcott to work doing what he did best, hunting for fossils. Walcott soon found signs of life similar to Hall's
Cryptozoon
. More significant, he found them in what were almost certainly Precambrian rocks. In 1891, Walcott wrote that “there can be little, if any, doubt” that life indeed existed in Precambrian seas, but not until 1899 did he find the definitive evidence he was looking for. Twenty years after first being intrigued by Hall's
Cryptozoon
, Walcott discovered in the Grand Canyon the fossilized remains of microscopic, single-celled algae that he named
Chuaria
after the rock strata in which they were found. Though his discovery remained controversial into the twentieth century,
Chuaria
-like fossils have now been dated to as far back as 1.6 billion years. Walcott had finally found the answer to Darwin's missing piece of the fossil record. Eventually, even older fossils would be found, and scientists would come to accept that simple life-forms had existed for at least 3.5 billion years of the Earth's 4.5-billion-year history.

B
Y THE TIME
Oparin and Haldane set about formulating their theories of the origin of life, they understood that the Earth was vastly older than any of their predecessors could have imagined. This was a crucial point because it meant that the environment of the planet when life first arose was probably nothing like that of the modern world. Oparin and Haldane could
throw out the old assumptions about spontaneous generation—that any appearance of life from nonlife should be repeatable in an environment that would now be familiar to us—and instead speculate on what kind of world it would have taken to produce life.

As Oparin set about working out his theories in the 1920s, and particularly in his 1936 book, he could draw on those facts to paint a new picture of a young Earth as it existed hundreds of millions or even billions of years earlier. It was an Earth so vastly different that it might as well have been an alien planet, its atmosphere
in particular would have been different.

Figuring out which elements had to be present was the easy part. Broken down to their most basic chemical parts, all living things are remarkably similar. They are also remarkably simple. From the smallest bacteria to the cells of the most complex species, living organisms are made primarily of carbon, hydrogen, oxygen, and nitrogen, the four basic elements of life that chemists often refer to by the acronym CHON. Other elements are found in trace amounts, most important among them sulfur and phosphorus, but about 98 percent of every living thing is made up by weight of the four elements C, H, O, and N.
^‡
Each of those elements was almost certainly abundant on Earth, and just about everywhere else. They are, in fact, four of the seven most common elements found in the universe.

The hard part was understanding how these elements combined to form the more complex molecules required for life. The CHON elements may have been present, but their form on the primitive Earth was still an open question. Was the oxygen present only in water (H
₂
O), or was it also free as O
₂
gas in the atmosphere, as is true of the modern Earth? To understand how life may have come about required first understanding what kinds of chemical
compounds
were available at the time.

Oparin began with an assumption that there was no free oxygen gas in the primitive atmosphere. From astronomical observations that had been made of Jupiter, Oparin deduced that the early Earth's atmosphere was filled with methane and ammonia. It was also an environment bathed in external energy, bombarded from above by cosmic rays and ultraviolet radiation, unchecked by the modern Earth's ozone layer. The surface was wracked by constant volcanic activity far beyond anything experienced today. Excited by the bombardment of solar radiation and heated by the energy released by volcanoes, the atmospheric gases would have broken down into their constituent parts. These would have recombined into new compounds, some of which would have dissolved into the vast seas that covered most of the planet. This long chain of chemical events would have led to the synthesis of organic compounds and, eventually, to some sort of precellular structure that represented an intermediate stage between nonlife and life. Haldane's vision of the early Earth was strikingly similar, and the areas of consensus between the two men's theories formed the basis of the Oparin-Haldane hypothesis.

In the decades to follow, as scientists learned more about the geological and astronomical conditions that had existed when life first appeared on Earth, several elements of the Oparin-Haldane hypothesis proved remarkably resilient. Geochemistry, the study of the ways the fundamental laws of chemistry can be used to explain planetary processes, would prove by the end of the century that the early Earth's atmosphere did not, in fact, contain much oxygen—a condition that lasted for almost two billion years after the Earth's formation, until biology invented oxygen-generating photosynthesis. And the lack of oxygen meant that the atmosphere would have had little ozone, leaving the Earth unprotected from ultraviolet radiation from the sun.

This last fact, the high flux of energy, was extremely important in both Haldane's and Oparin's theories. It was the driving force for the natural synthesis of organic compounds. The compounds intermingled, forming simple molecular aggregates. These were simpler than any single-celled organism we would know of today, but complex enough to convert organic compounds into more copies of themselves. Some of them attained enough complexity that Haldane called them “half-living.” Oparin called these
molecular aggregates “coacervates.”

At this point, Haldane's and Oparin's visions diverged in ways that would be increasingly significant in the decades ahead. Each man had a different idea of what made something living. Oparin saw the key as cellular metabolism, the collection of chemical reactions that transform external foodstuff into living material. Life for him was a chemical process, and its essential components were proteins that helped these processes occur. This school of thought came to be known as the “metabolism first” tradition.

For Haldane, the key to life lay in the gene. His concept of an intermediate stage between life and nonlife was influenced by the phenomenon of viruses, which scientists then understood in only a rudimentary fashion.
^§
Considerably smaller than bacteria, viruses would not be seen under microscopes until 1933, and there was considerable disagreement as to whether or not viruses were, in fact, living. Haldane was particularly intrigued by something called a bacteriophage, a virus that infected bacteria and seemed to Haldane to hold characteristics that might lead it to be called “half-living.” In 1915, the French-Canadian microbiologist Félix d'Herelle was struggling to understand why water from India's Ganges and Yamuna Rivers seemed to have the remarkable trait of being able to protect people from cholera. Both rivers were filthy with sewage and teemed with harmful bacteria. D'Herelle found that the rivers also contained a remarkable “bacterium eater,” which some observers soon claimed possessed the ability to self-replicate within cells.

T
HE UNIQUE PERSPECTIVES
on biology held by Haldane and Oparin were shaped by the very different scientific worlds in which the two men worked. In the Soviet Union, the field of genetics was increasingly seen as a “bourgeois science,” based on a kind of “survival of the fittest” model that was anathema to the Marxist ideal. In the West, the study of genetics was revolutionizing
biology, and Haldane was one of the field's most important elaborators and theorists.

Though the basic tenets of genetics had been elaborated in the mid-nineteenth century by the Franciscan friar Gregor Mendel, his work had gone almost entirely unnoticed until 1900, when several scientists independently realized the importance of what Mendel had discovered. The concept was quickly embraced, and by 1906, scientists were using the term “gene” to describe the unit of inheritance.

Haldane had been on the forefront of genetics since the very beginning. In 1901, when he was nine, his father had taken him to one of the earliest lectures on Mendel's theory. Genetics became one of his favorite subjects and remained so for the rest of his life, occupying much of his writing and experimental work. Haldane was instrumental in establishing the interlocking relationship between Darwin's theory of natural selection and Mendel's theory of heredity.

Acceptance of genetics in the Western world was swift. The basic concepts were easy enough to explain and to prove, even to a child of nine like Haldane. Yet, by the mid-1920s, the study of the gene was increasingly being brushed aside in the Soviet Union, where Joseph Stalin was forcing the scientific establishment more and more to conform to his totalitarian view of Marxism, in which genetics and “survival of the fittest” were seen at odds with the utopian vision of absolute equality.

The worst excesses of the period were personified in one scientist in particular, the agronomist Trofim Lysenko, who for two decades almost single-handedly managed to retard the science of genetics in the Soviet Union. The son of an illiterate peasant farmer, Lysenko was a little-known scientist working in the Ukraine when
Pravda
first profiled him in a 1927 article on Soviet farming titled “The Fields in Winter”: “If one is to judge a man by first impression, Lysenko gives one the feeling of a toothache. All one remembers is his sullen look creeping along the earth as if, at the very least, he were ready to do someone in.” As Lysenko rose up the ranks of Soviet bureaucracy through brutal Machiavellianism and Stalinist sycophancy, the description proved to be remarkably prescient.

Lysenko was one of the holdouts of Lamarck's increasingly marginalized
theory of acquired characteristics. Lamarckian theory was central to Lysenko's attempts to breed crops that would be more resilient in winter. His claims that he had developed a method to convert spring wheat into winter wheat proved disastrous for Russian agriculture, which was already reeling from the inefficiencies of mass collectivization. In the years to follow, millions died of starvation.

Yet Lysenko shrewdly used his peasant background to endear himself to Stalin and quickly rose to a commanding position in the Soviet biological sciences. The results of his stewardship were catastrophic. Most scientists working under Lysenko caved in to the climate of fear, adjusting their theories to conform to Marxist dogma as expounded by men like Lysenko. Those who did not sometimes paid with their lives.

One of Lysenko's victims was Nikolai Vavilov, the geneticist who had sponsored Haldane on his first trip to Russia. Vavilov was one of the most prominent Mendelian holdouts to resist Lysenko, though he otherwise bent over backward to win the Ukrainian's favor. Vavilov had even sponsored Lysenko's membership in the Ukrainian Academy of Sciences. In 1940, Vavilov was nevertheless arrested on charges of espionage. A sentence of death by firing squad was commuted to twenty years in prison. He died two years later of starvation. By 1948, nearly all geneticists were being called before Communist Party meetings and forced to recant.

Oparin's role in Lysenko's reign of terror remains a dark stain on his career. The two men shared summer dachas together and were known to be friendly, though in the Orwellian world of Stalinist Russia, it was hard to know how much of their friendliness was genuine. Marxism certainly affected Oparin's work. Especially in his early years, Oparin really did seem to be the kind of true-believer communist scientist that became so rare in the later days of the Soviet Union, after years of oppression had squeezed out what little authentic idealism the scientific community could muster. In some ways, Oparin's broad approach to the question of the origin of life could be traced to his embrace of Marx's historical dialectic. He was probably helped by the fact that scientists in the Soviet Union tended to be less trapped into a single discipline than their Western counterparts were. In his emphasis on the slow but deliberate evolutionary steps that led
from nonlife to life, Oparin tried to keep close to a theory on the origin of life that had been posited by Marx's collaborator Friedrich Engels in his book
Dialectics of Nature
. Though Oparin never incorporated Lysenko's theories into his own work, until the 1950s he shied away from touching on the questions of genetics that would come to dominate origin-of-life research by the end of the century.
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