myself: that our planet and the life on it are too beautiful and “well
designed” to have just happened by accident.
Ultimately, I did not change my mind and reject Darwinian evolution. I
realized that the character of evolutionary change is such that a highly
evolved system will, after hundreds of millions of generations of trial and
error, be so optimized for survival that it will seem, upon first examina-
tion, to have been designed by an imaginative, clever, and ingenious mind.
O C C A M ’ S R A Z O R
We cannot prove that no other force, such as divine or alien interven-
tion, has directed evolution. But the scientific attitude, which I find very
appealing, is to reject any hypothetical, hidden mechanisms when
known mechanisms are adequate to do the job. We have a name for
this attitude. We call it Occam’s razor after the fourteenth-century
monk William of Occam, who said, “It is vain to do with more what
can be done with fewer.” We take this to mean, “Why assume that
things are complicated if a simple theory can explain all of the observa-
tions?” The razor is a tool we use to cut the crap from theories that
seem too contrived to describe the apparent simplicity of nature.
We assume that the universe is simple until proven complicated. Why
invoke forces, mechanisms, creatures, or gods that are not really neces-
sary to explain what we observe? For scientists, such arguments are
almost as good as proof. Science is driven by a belief that there are sim-
ple laws, which we can discover, that govern the behavior of much of
the universe. If we can conceive of multiple explanations for a given
observation, the simpler explanation is more likely to be true.
Why do we believe this? Science is supposed to have no dogmas, to
be ready to question and discard every idea if the evidence does not
support it. Is there any logical, a priori reason to believe that the uni-
verse should be explicable with simple laws? Or is this merely received
knowledge, an article of (gasp, shudder) faith?
I think that it is more an aesthetic principle: Wouldn’t it be nice and
elegant if the universe turned out to follow simple laws that we can
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figure out? The original Copernican revolutionaries advocated a
Sun-centered solar system largely out of an aesthetic preference for this
scheme, compared to the more complex and cumbersome arrangements
required to keep everything spinning around the Earth.
Or, perhaps we believe in it because it works. You can think of
Occam’s razor as a hypothesis about the natural world, a position to
take for the sake of argument, an idea to try on the universe to see if it
fits. After all, you’ve got to start by assuming something to get any-
where in science. Then your results serve to test your initial assump-
tions, and you either confirm or reject them as you proceed.
In the case of Occam’s razor, the “results” are the hundreds of years
of progress made with science. Science, guided by the search for sim-
plicity, has uncovered many deep patterns and hidden connections in
our universe. All of the inventions that work, and the predictions that
come to pass, help to confirm the original working hypothesis. Science,
operating under the doctrine of simplicity, clearly works. That means
it’s a good assumption. A keeper. I would describe Occam’s razor as a
hypothesis, based on an aesthetic intuition, that has proven to be
“true” in the sense that it is quite fruitful.
I find the logic and the evidence of evolution to be completely con-
vincing. A deep look at the world, digging into the rocks and dirt,
shows a record of change and adaptation. The mechanisms described
by Darwin, tweaked with 150 years of subsequent insights, mar-
velously equip us to understand this process. Given variation, death,
and heredity, there is no escaping that evolution will happen. Fossils
and numerous other clues show clearly that it has. For the scientific
mind, guided by Occam’s razor, there is no reason to invoke any other
force in evolution, and the case is closed.
M I C R O C O S M I C G O D S
All living cells, from the bacteria lounging in your gut to the neurons
humming in your brain, depend on an intricate pas de deux between
nucleic acids and proteins. Neither can be made without the assistance
of the other. The DNA code cannot be read without an elaborate pro-
tein transcription machine. The machine cannot be built without the
code. Once it’s up and running, this system works wonderfully. But it
presents us with a serious chicken-and-egg problem. Which came first,
proteins or DNA? And how did such a tangled web evolve?
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In a more general sense, the problem of getting from organics to
organisms is still unsolved. There is a large gulf between the most com-
plex self-replicating molecules that we can easily imagine arising from
chemical evolution and the incredibly elaborate chemical machinery
common to all cells. There is still vast, unmapped territory bordered by
the familiar lands of chemistry on the one side and biology on the other.
Many scientists are seeking to retrace the route that nature evidently
found across this terra incognita. In this quest we have found many
promising leads that point from chemistry toward biology and, on the
other side, bits of biochemistry that seem to hint at nonliving precursors.
One of the cool things about having Carl Sagan as a friend and men-
tor was that he was constantly feeding me reading tips. Mildly disap-
proving of my hard-core science fiction habit, he tried, during my teen
years, to steer me toward “good” science fiction. Once, Carl gave me a
short story that he described as one of his favorites: “Microcosmic
God” by Theodore Sturgeon.* The story, written in 1941, concerns an
iconoclastic biochemist, James Kidder, who worked on an island off
New England. Fascinated by the mystery of life’s origin, he endeavors
to create life in his laboratory: “When the cloudy, viscous semifluid on
the watch glass began to move of itself he knew he was on the right
track. When it began to seek food on its own he began to be excited.
When it divided and, in a few hours, redivided, and each part grew and
divided again, he was triumphant, for he had created life.”
He not only succeeds in creating primitive organisms, but also learns
to accelerate metabolism, so that his creatures pass through many gen-
erations in a single hour.† The evolutionary process speeds up to a
dizzying pace. As weeks and months go by, he observes his creations
passing through many of the phases that took billions of years for
nature to achieve on Earth. Things get interesting when they develop
intellectual and technological abilities vastly exceeding those of human
beings. Fortunately for Mr. Kidder, his “Neoterics” have always wor-
shiped him as their god, which, practically speaking, he is. They have
no such respect for the rest of humanity, however. Let’s
just say that the
military is called in, but beyond that I won’t spoil the ending.
*Sturgeon was one of Carl’s favorite SF writers. He also wrote several Star Trek episodes.
Which is funny, because Carl hated Star Trek. The week of the Viking 2 landing on Mars, his son Dorion and I got him to sit through “The Menagerie,” the pilot episode of the original Star Trek. Carl admitted that it was much better than he’d expected.
†Part of the secret comes from chemicals he extracts from Cannabis indica!
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A few months after reading this story, I had a summer job as an
undergraduate intern working in Carl’s Planetary Simulation Lab at
Cornell. Most of that summer (1978) I spent working closely with Reid
Thompson, Carl’s grad student and a brilliant chemist. Reid was an
animated and patient teacher with a wrestler’s build and a thick beard.
Blessed with a Kentucky accent and a rambling Southern sense of
humor, he had a passion for fast American cars with powerful engines,
and he possessed an encyclopedic knowledge of many subjects, includ-
ing organic chemistry and trees. As we walked to lunch every day, he
would tell me about the trees lining the pastoral walkways of Cornell—
their species, ancestry, seasonal growth patterns, sexual preferences,
whatever. On the way back from lunch, he would quiz me.
There were many other enticements that summer: the Ithaca music
scene, the local skinny-dipping pond, a girl named Katie, and the fire-
flies dancing around the cemetery at night. I was eighteen and living in
a group apartment in College Town that never had anything but beer in
the fridge, so some mornings I would be moving a little slow. But Reid
was tolerant, even a bit of a mischievous rebel himself, and the work
was engaging enough to compete for my attention with raging hor-
mones and experiential curiosity. Spending days in the lab with Reid
was always a good time.
Recall the groundbreaking experiments of Miller and Urey in 1953,
which made the first baby steps down the route from chemistry to biol-
ogy by showing that amino acids are easily made in conditions simulat-
ing the early Earth. That summer we were doing a series of experiments
that were the evolved descendants of the Miller-Urey experiment, trying
to induce the first steps of organic evolution in a range of conditions
simulating the environments of other planets. We set up an impressive
array of glassware, including a maze of coiled tubes for heat exchange,
“cold fingers” encased in liquid nitrogen for trapping condensed gases,
valves, flasks, and chambers in which we could subject gas or liquid
mixtures to various provocations: heat, cold, ultraviolet radiation, or
electric shock. The whole sprawling contraption was held together
with clamps extended from a scaffolding of metal rods. It was the pro-
totypical mad scientist’s lab, complete with foul-colored bubbling mix-
tures and electric discharge chambers. We did not wear white lab coats,
even though we would have been screwed if government auditors had
shown up.
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Carl was fascinated by the results of the Miller-Urey experiments
(Urey was one of Carl’s scientific mentors) and the further questions
they implied: What is the range of environments in which biologically
promising organics can be made from simple, ubiquitous chemicals?
Could it happen in the clouds of Jupiter? On Saturn’s gas-shrouded
moon Titan? In the surface layers of carbon-rich icy moons?
Not at all an exact science, this lab work proceeds by hunches and
trial and error. At the end of an experimental run, you are left with
your precious chemical product: a sealed flask with some unknown
gases or a residue of yellowish or brown crud. You analyze this gunk
with a range of high-tech instruments, and depending on what you
find, you then start over with a modification of the original experiment.
We’ve learned from such experiments that it is surprisingly easy to
make the organic preludes to life in various environments that exist in
the solar system and elsewhere. Take a source of carbon, the fourth most
common element in the universe (after hydrogen, helium, and oxygen),
add some hydrogen, nitrogen, oxygen, sulfur, and phosphorous, tap into
a sufficient source of energy, and you almost inevitably get amino acids
and other simple but vital organic precursors. One thing the experiments
of Reid Thompson and his colleagues showed was that the necessary
first steps toward organic life should occur commonly throughout our
universe. Reid died in 1996 of cancer, which seems to be an occupational
hazard of experimental chemists (although in his case I have no idea if
there was any connection). I’ll always be grateful for the tutelage I
received from him among the glass tubes and tall trees of Cornell.
In the fall of 2000, twenty-two years after that summer at Cornell, I
served on NASA’s review panel evaluating new proposals for funding in
exobiology. This particular panel meeting was in some ways not unlike
a cult indoctrination. There we were, locked in a small, air-conditioned
building surrounded on all sides by the deadly cultural desert of south-
ern Houston, thirteen scientists in close quarters, reviewing ninety-one
research proposals in four days. We were immersed in the material con-
stantly from sunup to well after sundown, barely leaving to sleep and
eat. By the third or fourth day of sleep deprivation, this kind of experi-
ence would start to take on a surreal air even if you weren’t reading
about fishing for alien squid beneath the ice of Jupiter’s moon Europa.
Though it is customary to complain about being fingered for a NASA
review panel (no, you don’t get paid), it can be fascinating and fun.
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There is that peculiarly giddy sense of camaraderie that comes only
from focused group concentration over long hours—it reminded me of
cramming for finals with fellow students or all-night recording sessions
with various forgotten bands. Forced to endure such conditions, nerds
can get pretty silly by the end of the broadcast day.
Like a voyeuristic stroll down a dark city street, peeking into random
rooms and lives, an assignment to a review panel gives you a great
glimpse into random labs and minds. For me, serving on this panel pro-
vided a wonderful opportunity to see what kind of research into life
elsewhere NASA was funding, and what was being proposed but not
funded.
Because astrobiology, or exobiology as it is still called in this particu-
lar NASA program, is an attempt at forging a metafield from many dis-
ciplines, I was closeted not only with fellow planetary scientists but also
with biologists, geologists, chemists, and others. The attempts at cross-
disciplinary communication, some more successful than others, were
enlightening. One proposal came from a cosmologist who said he
could explain some important mysteries of biology using simple struc-
tural principles adapted from cosmo
logy. The physical scientists (astron-
omers, planetologists, chemists) looked at it and thought, “Cool! Why
not?” We thought it was insightful, innovative, and deserving of the
highest rating. The biologists on our panel looked at it and thought,
“How dare he? Who the hell is this guy? This makes no sense.” They
regarded it as naive, foolish, grandiose, and entirely undeserving of sup-
port.* This extreme case of interdisciplinary cognitive dissonance
reminded me of the challenges facing us as we search the universe for
something we all desperately seek but can’t exactly define.
I was particularly interested to see what kinds of experiments
chemists are now doing in origin-of-life studies. We didn’t see any pro-
posals that claimed, “We will be as Microcosmic Gods and create life
itself from inanimate matter!” But, in fact, many groups are chipping
away at that problem from several different angles, mapping the
uncharted pathways of organic matter, seeking life’s primordial route
out of the chemical wilderness.
My overall impression was that the field had not advanced greatly
since the late 1970s when Reid and I had fooled around with organic
*Unfortunately, for legal and ethical reasons, I can’t be more specific.
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synthesis at Cornell. What Miller and Urey had done in their lab and
Sagan had done in his lab with help from young lackeys like me, several
groups were still attempting: making organics from mixtures of simple
chemicals, egging them on with various energy sources, and analyzing
the results. It’s still as much art as science. We’ve mapped out many
possible parts of the path from chemistry to biology, but the overall
route is still far from clear. Our experiments in prebiotic chemistry are
still more like medieval alchemy than we would like to admit. You add
a little of this, take out a little of that, and see what you get. It’s more
like cooking than quantum mechanics. We are like those earliest bio-
molecules, casting about in a sea of enticing chemicals, hoping to find
some magic.
T H E M I S S I N G L I N K : R N A W O R L D ?
What was the evolutionary step, or series of steps, between simple self-
replicating molecules and the elaborate reproductive machinery common
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