by Charles Baum
the power of science and the futility of the creationists’ task. Sci-
ence makes specific, testable predictions. Anyone can go out into
the natural world and test those predictions. The creationists were
wrong.
Today’s creationists have toted out a new version of this old
INTERLUDE—GOD IN THE GAPS
79
Ambulocetus
Rodhocetus
Basilosaurus
The evolution of whales is illustrated by recent fossil finds, including Ambulocetus (52 million years old), Rodhocetus (46 million years old), and Basilosaurus (35 million years old) (from National Academy of Sciences, 1999).
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GENESIS
“God-in-the-gaps” argument under the fancy name “intelligent
design.” Their argument goes like this. Life is so incredibly com-
plex and intricate that it must have been engineered by a higher
being. No random natural process could possibly lead from non-
life to even the simplest cell, much less humans. The promoters,
notably Michael Behe and William Dembski, don’t talk about
“God,” but they leave open the question of who designed the
designers.
Such an argument is fatally flawed. For one thing, intelligent
design ignores the power of emergence to transform natural sys-
tems without conscious intervention. We observe emergent com-
plexity arising all around us, all the time. True, we don’t yet know
all the details of life’s genesis story, but why resort to an unknow-
able alien intelligence when natural laws appear to be sufficient?
I also see a deeper problem with intelligent design, which I
believe trivializes God. Why do we have to invoke God every
time we don’t have a complete scientific explanation? I am
unpersuaded by a God who must be called upon to fill in the
gaps of our ignorance—between a cow and a whale, for example.
The problem with this view is that as we learn more, the gaps
narrow. As paleontologists continue to unearth new intermediate
transitional forms, God’s role is squeezed down to ever more
trivial variations and inconsequential modifications.
Isn’t it more satisfying to believe in a God who created the
whole shebang from the outset—a God of natural laws who
stepped back and doesn’t meddle in our affairs? In the beginning
God set the entire magnificent fabric of the universe into motion.
Atoms and stars and cells and consciousness emerged inexorably,
as did the intellect to discover laws of nature through a natural
process of self-awareness and discovery. In such a universe, sci-
entific study provides a glimpse of creator as well as creation.
Part II
The Emergence of Biomolecules
The top-down study of life’s origin—via the examination of ancient
fossils—doesn’t tell us much about early biochemistry. Fossil cells,
molecules, and isotopes are indistinguishable from those of contem-
porary life-forms; consequently, from them we can gain detailed
knowledge only of the final state—modern cellular life.
Nevertheless, common sense points to the essential first step in
life’s emergence—the synthesis and accumulation of abundant organic
(that is, carbon-based) molecules, such as amino acids, sugars, and
other vital molecules of which life would eventually be made. In the
beginning, life’s raw materials consisted of water, rock, and the sim-
plest and most basic volcanic gases—carbon dioxide, nitrogen, and
maybe a little methane and ammonia. Add energy to the mix and or-
ganic molecules emerge.
The experimental pursuit of this ancient process, arguably the best
understood aspect of life’s chemical origins, began in earnest just over
a half-century ago, with the pioneering studies of University of Chi-
cago graduate student Stanley Miller and his distinguished mentor,
Harold Urey. Together they demonstrated the organic synthesis that
occurred as Earth’s primitive atmosphere and ocean were subjected to
bolts of lightning and the Sun’s intense radiation. Chemical processes
in deep space, in the solar nebula, during asteroid and comet impacts,
and even within the pressure cooker of Earth’s deep interior, also gen-
erated abundant organic molecules. By 4 billion years ago, Earth’s
globe-spanning ocean must have become a complex, albeit dilute, soup
of life’s building blocks. Though not alive, this chemical system was
poised to undergo a sequence of increasingly complex stages of mo-
lecular organization and evolution.
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6
Stanley Miller’s Spark of Genius
The idea that the organic compounds that serve as the basis of
life were formed when the earth had an atmosphere of
methane, ammonia, water, and hydrogen instead of carbon
dioxide, oxygen, and water was suggested by Oparin and has
been given emphasis recently by Urey and Bernal. In order to
test this hypothesis an apparatus was built. . . .
Stanley L. Miller, Science, May 15, 1953
The experimental investigation of life’s origin is a surprisingly re-
cent game. Two centuries ago, many scientists accepted the intu-
itively reasonable idea, championed by Aristotle and a pantheon of
other ancient scholars, that a life force permeates the cosmos. A central
precept of this doctrine, known as vitalism, is that life arises spontane-
ously all around us, all the time. The question of life’s origin wasn’t
asked—at least not in the modern experimental sense.
Think about your own experience and you’ll see why this idea of
spontaneous generation isn’t such a strange notion. Mold seems to
grow spontaneously on bread, maggots appear as if by magic in old
meat, and every spring new plants sprout and grow in the season of
renewal. It’s not surprising that so many people, for so long, accepted
unquestioningly the spontaneous generation of life.
This view continued well into the nineteenth century, though not
without a number of respected dissenters and considerable debate. The
seventeenth-century invention of the microscope and the subsequent
realization that microscopic life abounds complicated the story, but
failed to resolve the controversy. Those who favored spontaneous gen-
eration saw microbes as just another manifestation of the life force;
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84
GENESIS
those opposed saw microscopic life as an obvious source of experi-
mental contamination.
The interpretation of experiments is rarely unambiguous, as high-
lighted by a delicious eighteenth-century exchange. The noted Italian
physiologist Lazzaro Spallanzani explored spontaneous generation by
comparing the behavior of boiled and unboiled sealed flasks, each filled
with bacteria-infested, nutrient-rich water. He found that flasks boiled
for an hour remained sterile indefinitely as long as they remained
sealed, whereas unboiled flasks quickly became cloudy with microbes.
Spallanzani concluded that ubiquitous microscopic life-forms con-
taminate any unsterilized experiment.
Englishman John Needham, an astute
amateur experimenter who
conducted his own fragrant experiments on hot mutton gravy, came to
a different conclusion. Needham agreed that boiling kills microbes, but
microbes soon reappeared in abundance when his gravy cooled. He
argued that these cells arose by spontaneous generation. Spallanzani
countered that Needham’s microbes came from airborne contamina-
tion and, to prove his point, he undertook a new series of experiments
in which he demonstrated that no microbes appeared when he pumped
air out of his flasks and then boiled the water. Needham disagreed: A
property of the air, not the water, must carry the life force, he said.
We react to this historical incident with a biased worldview. Of
course Spallanzani’s conclusions about microbial contamination were
right and Needham’s support of spontaneous generation was wrong,
we are tempted to say. But a naïve and impartial observer of the time,
faced with these conflicting claims, would have had a difficult time
choosing between invisible microbes and an invisible life force. Both
arguments were internally consistent, so doubts remained.
The influential French chemist Louis Pasteur helped to abolish vi-
talism and the theory of spontaneous generation once and for all with
his own brilliant series of experiments on sterilization. He prepared a
nutrient-rich sugar solution and poured it into several beakers. One
set of beakers was tightly sealed to prevent any contact with the ambi-
ent air. Other beakers were left open with a narrow twisting neck, so
that the sugar solution was in contact with the ambient air, but un-
likely to be contaminated by stray microbes, which were unable to
traverse the long glass passage. As a control, he left other beakers wide
open or deliberately contaminated them with ordinary dust. He
showed that boiled water, if isolated from airborne microbes, remained
STANLEY MILLER’S SPARK OF GENIUS
85
sterile indefinitely. Only microbial contamination causes new growth,
not spontaneous generation—a result of tremendous practical as well
as theoretical consequence. His discoveries proved of immense impor-
tance in reducing the incidence of infectious diseases, while his devel-
opment of the pasteurization process transformed the production and
preservation of food and, perhaps more important to French mer-
chants, beer.
In the course of his elegant work, Pasteur also contributed di-
rectly to the study of life’s origin. By introducing the dictum that no
life can occur without prior life, his findings pushed back life’s origin
to an inconceivably remote time and place. How could anyone make
observations or perform experiments to study an event so ancient and
inaccessible?
SPECULATION
In 1871, Charles Darwin penned a speculative letter to his friend, the
botanist Joseph Hooker. “If (and Oh! What a big if !),” he wrote, “we
could conceive in some warm little pond, with all sorts of ammonia
and phosphoric salts, light, heat, electricity, etc., present, that a protein
compound was chemically formed ready to undergo still more com-
plex changes. . . .” Many contemporary chemists must have agreed that
life’s origin, wherever and however it occurred, depended on three key
resources.
First and foremost, terrestrial life requires liquid water, the essen-
tial growth medium for all living things. All living cells, even those that
survive in the driest desert ecosystem, are formed largely of water. Our
bodies are typically 70 percent water, while many foods are even more
water-rich. Surely the first cells arose in a watery environment.
Life also needs a ready source of energy. The radiant energy of the
Sun provides the most obvious supply for life today, but bolts of light-
ning, asteroid impacts, Earth’s inner heat, and the chemical energy of
certain unstable minerals have also been invoked as life-triggering en-
ergy sources.
And, third, life depends on a variety of chemical elements. All
known living organisms consume atoms of carbon, oxygen, hydrogen,
and nitrogen, with a bit of sulfur and phosphorus and other elements
as well. Atoms of these elements combine in graceful geometries to
form essential biomolecules.
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GENESIS
In spite of the intrinsic importance of the topic, Darwin’s private
musings about a chemical origin of life (which he never published)
flew in the face of conventional theology. “In the beginning, God cre-
ated” was sufficient for most people, including a majority of the most
distinguished scholars of the time. Not until the 1920s did such scien-
tific speculation take a more formal guise.
Most notable among that pioneering modern school of origin
theorists was the Russian biochemist Alexander Oparin. In 1922, while
still in his twenties and under the scrutiny of the Soviet hierarchy,
Oparin elaborated on the idea that life arose from a body of water that
gradually became enriched in organic molecules—the so-called
“Oparin Ocean” or the “primordial soup.” Somehow, he posited, life
emerged as these molecules clustered together and self-organized into
a chemical system that could duplicate itself. In many other cultures,
where religious doctrine colored thinking on origins, these revolution-
ary ideas would have been seen as heretical, but Oparin’s ideas reso-
nated with the materialist philosophical worldview of the Soviet
leadership.
Many of Oparin’s postulates were echoed in 1929 in the indepen-
dent ideas of British biochemist and geneticist J. B. S. Haldane.
Haldane, himself a Marxist activist, contributed a brief, perceptive
(many contemporaries would have said radical) article entitled “The
Origin of Life” to the eclectic secularist British periodical The Ratio-
nalist Annual. He speculated on the production of large carbon-based
molecules under the influence of the Sun’s ultraviolet radiation. Given
such a chemical environment, Haldane envisioned the first living ob-
jects as self-replicating, specialized molecules.
Oparin and Haldane offered original and intriguing ideas. More
important, their ideas were subject to experimental testing, but for
some reason Oparin and his contemporaries didn’t try. It wasn’t until
after World War II, a time of exuberant, can-do scientific optimism,
that two chemists demonstrated a systematic experimental approach
to prebiotic chemistry.
EXPERIMENTS
The apparently universal requirements of water, energy, and chemicals
hint at a simple experimental approach for studying the origin of life.
Such landmark experiments were devised early in the 1950s by Univer-
STANLEY MILLER’S SPARK OF GENIUS
87
sity of Chicago chemist Harold Urey, a Nobel Prize winner of great
renown, and his unknown second-year graduate student, the 23-year-
old Stanley Miller.
Jeffrey Bada, a Miller student in the 1960s and an unswerving pro-
ponent of his teacher’s ideas in subsequent years, rev
eals some of the
behind-the-scenes context of the historic Chicago work in his 2000
book (coauthored with Christopher Wills), The Spark of Life. Urey
planted the seed for the now classic experiment in the fall of 1951,
when he presented a seminar attended by Miller, who was a beginning
graduate student. In that lecture and related publications, Urey pro-
posed that life-triggering organic molecules might have been produced
in abundance in a plausible primitive atmosphere of hydrogen, meth-
ane, and other relatively reactive gases.
A year later, after trying his hand at an unsuccessful project in
nuclear theory, Miller asked Urey if he could attempt an experiment
with the hopes of synthesizing amino acids, the building blocks of pro-
teins. At first, so the story goes, Urey was reluctant and wanted Miller
to try an easier, safer research project. But after continued pressure
from Miller, Urey relented and gave his student a limit of one year to
make headway.
Scientists revere simple, elegant experiments, and that’s exactly
what Miller and Urey devised—a primitive Earth sitting on a tabletop
in a sealed glass vessel. [Plate 5] To the lower left, Miller positioned
a 5-inch-diameter (300-milliliter) flask filled two-thirds with water—
the primitive ocean. Glass tubing linked that flask to a 10-inch-
diameter (5-liter) gas-filled flask, situated above and to the right.
Miller’s atmosphere consisted of the relatively reactive gases methane
(CH , sold commercially as natural gas), ammonia (NH , the strong-
4
3
smelling component of ammonia-based cleaners), and hydrogen (H ,
2
the explosive lighter-than-air gas of Hindenberg fame). Two pointed
metal electrodes penetrated the upper flask to simulate “lightning” by
sparking, and a flame gently heated the water-filled flask to mimic the
ocean’s continuous evaporation. Sending sparks through a potentially
explosive mix of hydrogen and methane is not for the faint of heart,
nor would Miller’s unshielded glass apparatus have stood up to today’s
government safety standards. But it was an elegant experimental
design.
Following academic tradition, Miller the student performed the
experiments, while his mentor waited in the wings. Miller began by
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GENESIS