Heather DeLancett Biology 101 – Spring 2011 Prof. Grant Gerrish What is Life – The Fifth Miracle? Sometimes the mind comes across a question which jostles it out of the security of a myriad of assumptions previously taken for granted. After a visit to Crater Lake in Oregon last fall, one such question came upon me and took up a relentless presence. What is the difference between something that is alive and something that is not alive? It seemed on the surface to be a simple question to which everyone must know the answer, and yet, when I questioned my friends (and everyone else that night at the bar), I discovered that none of us came up with a satisfying answer. There was this gaping abyss of our “difference” explanation missing and we all felt it as the discussion went on. Finally someone with a fancy iPhone looked it up on Wikipedia and read off about 7 different criteria that were currently accepted for defining “life” – though there were exceptions and not everything needed to meet all the criteria. It all seemed rather loose and blurry even couched in technical sounding terms. By the end of the night, I was deeply disturbed by my own lack of knowledge about something I had assumed was well known.
Sometimes the mind comes across a question which jostles it out of the security of a myriad of assumptions previously taken for granted. After a visit to Crater Lake in Oregon last fall, one such question came upon me and took up a relentless presence. What is the difference between something that is alive and something that is not alive?
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Transcript
Heather DeLancett
Biology 101 – Spring 2011
Prof. Grant Gerrish
What is Life – The Fifth Miracle?
Sometimes the mind comes across a question which jostles it out of the security of a
myriad of assumptions previously taken for granted. After a visit to Crater Lake in Oregon last
fall, one such question came upon me and took up a relentless presence. What is the
difference between something that is alive and something that is not alive? It seemed on the
surface to be a simple question to which everyone must know the answer, and yet, when I
questioned my friends (and everyone else that night at the bar), I discovered that none of us
came up with a satisfying answer. There was this gaping abyss of our “difference” explanation
missing and we all felt it as the discussion went on. Finally someone with a fancy iPhone looked
it up on Wikipedia and read off about 7 different criteria that were currently accepted for
defining “life” – though there were exceptions and not everything needed to meet all the
criteria. It all seemed rather loose and blurry even couched in technical sounding terms. By the
end of the night, I was deeply disturbed by my own lack of knowledge about something I had
assumed was well known.
When you mentioned credit for book reviews, I immediately went to the UHH library
and perused the available choices. Several books got put on my “wish list” despite my already
totally overwhelming schedule this term. Erwin Schrodinger, a celebrated physicist who has
made my mind stretch in fascinating ways before, had written a short little treatise in 1944
titled: “What is Life?: The Physical Aspect of the Living Cell.” Very excitedly, I took this book
which seemed to summarize my exact quandary and I there began my investigation. Soon, I
realized that Schrodinger was not a man to waste words, and to properly report on this little 92
page book, complete with the Epilogue dedicated to the question of determinism and free will,
would essentially require the entire book’s duplication. I moved on to “The Fifth Miracle: The
Search for the Origin and Meaning of Life” published more recently in 1999 by Paul Davies, a
theoretical physicist, cosmologist and an astro-biologist. Davies starts his book with a preface
telling his own story of discovering Schrodinger’s little treatise and how it raised more questions
for him than it answered, leading him to assign the problem of biogenesis to the mental “too-
hard” basket for twenty years.1 I have come to (at least intellectually) respect both of these
men immensely.
Schrodinger’s Preface, penned in Dublin in 1944, immediately addresses one of the
issues which initially dissuaded me from scientific studies: the mandate of specialization to
exclusive cliques of jargon users who often do not attempt to communicate beyond the given
field of expertise. He says this is a matter regarded as “noblesse oblige”2 – a figurative
expression meaning that to claim a position (as a noble, or here as an expert) requires one to
act in accordance to those responsibilities and not waste time with idle pursuits. To this notion
of tradition which often prevents specialists from writing on topics outside of their area of
expertise, Schrodinger offers an argument based on the epistemological “inheritance we’ve
received from our forefathers” of “the keen longing for unified, all-embracing knowledge.”3 He
reminds us that even the name of our higher learning institutions is based on the value of the
universal aspect of knowledge being “the only one to be given full credit”4 from the time of
antiquity. Unapologetically, he states his position as one to which I can deeply relate:
But the spread, both in width and depth, of the multifarious branches of knowledge during the last hundred odd years has confronted us with a queer dilemma. We feel clearly that we are only now beginning to acquire reliable material for welding together the sum-total of all that is known into a whole; but, on the other hand, it has become next to impossible for a single mind fully to command more than a small specialized portion of it… I can see no other escape from this dilemma (lest our true aim be lost for ever) than that some of us should venture to embark on a synthesis of facts and
1 Paul Davies. The Fifth Miracle: The Search for the Origin and Meaning of Life. (New York: Simon & Schuster, 1999), p. 15.2 Erwin Schrodinger. What is Life? The Physical Aspect of the Living Cell (Cambridge: Cambridge Univ. Press, 1955), p. vii. 3 Ibid.4 Ibid.
theories, albeit with second-hand and incomplete knowledge of some of them – and at the risk of making fools of ourselves.5
Schrodinger then goes on to express his sheer wonder, from a physicist’s point of view, at the
mystery of life. He critiques the current limitations of his own discipline’s understandings by
pointing out that both physics and chemistry are statistical sciences, and asks what is in the
physicist’s “toolbox” that may contribute to learning more about life.
We can return to Schrodinger after a journey through Davies, as indeed this is actually
two book reviews in one and may get quite lengthy. An author I’ve recently cited in another
paper described in his own preface6 the concept of “archival density” – that of how many hours
per page a work required for adequate comprehension. Schrodinger’s work has a fairly high
“archival density” for me as a non-scientist, and probably for everyone else as well. But let us
consider two of his beginning questions before moving on: “How can events in space and time
which take place within the spatial boundary of a living organism be accounted for by physics
and chemistry?”7 and “Why must our bodies be so large compared to an atom?”8
By comparison, Davies has an archival density of zero – no one need spend an hour over
his written page because he masterfully guides the reader through various data and hypotheses
and problematic issues like a well-seasoned professor. In sharp contrast to Schrodinger, it is
easy to lose track of how much theoretical ground one has covered. Nonetheless, it certainly
has a cumulative effect on the mind. Let’s dig in!
Davies reports that Sir Arthur Eddington, a 20th century British astrophysicist who helped
to popularize general relativity theory, regarded the second law of thermodynamics as
occupying the supreme position among the laws of nature to the point that he wrote: “if your
theory is found to be against the second law of thermodynamics I can give you no hope; there is
nothing for it but to collapse in deepest humiliation.”9 The German physicist Hermann von
5 Ibid.6 Arthur L. Stinchcombe. Sugar Island Slavery in the Age of Enlightenment: The Political Economy of the Caribbean World. (Princeton, NJ: Princeton University Press, 1995). p. xiii.7 Erwin Schrodinger. What is Life? The Physical Aspect of the Living Cell (Cambridge: Cambridge Univ. Press, 1955) p. 1.8 Ibid. p. 6.9 Davies, p. 51.
Helmholtz, a founder of thermodynamic science, immediately suggested that living things
somehow circumvent this natural law which describes the “inevitable and irreversible trend
from ordered to disordered forms of energy.”10 This trend of useful energy loss is known as
entropy and continues towards chaos (deterministic distribution among molecules appearing
random but closely based on initial starting conditions) within closed systems until a maximum
entropy/disorder, known as thermodynamic equilibrium, is reached. But the very existence of
life, the formation of DNA, new species and increasingly diverse biospheres seem to exhibit an
increase of order and a decrease of entropy.
Schrodinger, in his treatise, observed that organisms avoid decay and maintain order by
“drinking orderliness” from the environment and questioned whether a new type of physical
law might apply to living matter, which might be exempt from entropy.11 Davies rejects this
second notion and points out that the living organism is not a closed system. Like a
refrigerator, working to reverse the entropy of heat production inside the box, living organisms
may increase internal organization by correspondingly increasing the level of disorder in the
environment around them. Applied to biological evolution, the appearance of a new species
marks the survival of a successful mutant, but thousands of unsuccessful dead ones are claimed
by natural selection. “The carnage of natural selection amounts to a huge increase in entropy,
which more than compensates for the gain represented by the successful mutant.”12 The
Austrian physicist Ludwig Boltzmann, another thermodynamic science founder, is thought to
have solved this apparent dilemma long ago by recognizing that as long as the environment can
provide a supply of free energy, biological organisms can have the niche of increasing their own
local order and contributing to the rise of entropy in the universe as a whole. Davies points out
that the concept of metastability (thermodynamic disequilibrium) is crucial to life because living
organisms get their useful energy from chemical reactions by overcoming the barriers “that
frustrate the inorganic release of the energy.”13 These free exploitable energy sources would
not exist at a state of thermodynamic equilibrium – all of the energy would be dispersed into
10 Ibid. p. 51-5211 Ibid. p. 52.12 Ibid. p. 54.13 Ibid. p. 55.
random heat. Boltzmann wrote: “Thus, the general struggle for life is neither a fight for basic
material…nor for energy…but for entropy becoming available by the transition from the hot sun
to the cold earth.”14 I guess that is one way of looking at our predicament as living creatures.
Contrasting snowflakes versus DNA, syntactic versus semantic “information,” Davies
continues “it is not enough to simply identify a source of free energy, or negative entropy, to
provide biological information. We also have to understand how semantic information comes
into being. It is the quality, not the mere existence, of information that is the real mystery
here.”15 Davies concludes that the source of semantic information can only be the environment
of the organism, but how did it get into the environment? He considers the chain of causation
to lead us back to wonder: “where did the information content of the universe come from?”16
Darwin had considered speculation about the origins of life to be as complex as speculations
about the origins of matter. Now physicists theorize a solution to the creation of matter within
the big-bang theory. Calculating the observable universe to contain 10ˆ50 tons of matter,
physicists have balanced the “something for nothing” creation of matter by postulating the
gravitational field to have negative energy. Particles of matter can be created (in our large
particle accelerator machines) if enough energy is concentrated. But where does all of the
energy come from to make the matter in the first seconds/moments of the universe? The
answer proposed in the 1980’s was that the total energy of the universe could actually amount
to zero due to the negative energy of gravity (that ever mysterious force!) essentially cancelling
out the equation.17 Convinced? Wait, it gets stranger…
Still looking for the origin of semantic information, Davies summarizes the conclusion
that if information can’t be made (which would violate entropy), it must have been part of the
initial input at the beginning of the universe. Despite our measurements of the cosmic heat
radiation suggesting a state of thermodynamic equilibrium, which would imply a minimum of
information, our universe clearly contains information. So the dilemma is that entropy “forbids
the total information content of the universe from going up as it evolves, yet, from what we can
14 Ibid. p. 54.15 Ibid. p. 60.16 Ibid.17 Ibid. p. 63.
tell about the early universe, it contained very little information.”18 How can the universe start
near thermodynamic equilibrium (or maximum entropy) and yet reach the present state of
disequilibrium without violating the 2nd Law of Thermodynamics? There it is again: Gravity.
Physicists theorize that as gravity becomes a feature upon a mass of gas, it throws the system
out of stability/equilibrium and creates an “entropy gap.” “The ultimate source of biological
information and order is gravitation.”19 However, even if we accept gravity as the source of life
and entropy gaps, we still lack an answer to how the semantic, meaningful information
emerged in the universe.
Davies states that both quantum mechanics and relativity theory suggest that
“information” is non-localized and global, rather than a local physical quantity. In quantum
mechanics, “the distinctive feature of the wave function is its so-called non-locality – it is spread
out across space and describes mysterious linkages between widely separated particles,
linkages that Einstein dubbed ‘spooky action at a distance.”20 It is often mistakenly assumed by
laypeople that in relativity theory nothing is permitted to move faster than the speed of light,
but this is not the case – relativity theory asserts that only the transmission of information
cannot exceed light speed. However, if information is a global rather than a localized quality,
this “spooky action at a distance” creates paradoxes which may have dramatic physical
consequences. This leads some physicists to hypothesize that we will be unable to trace the
origin of biological information to the operation of local physical forces and laws.21 Perhaps
some physical law governing non-locality will be discovered and our studies of complexity –
from galaxies to ecosystems to cells – will be revolutionized.
The Earth is estimated by radioactivity measurements to be about 4.55 billion years old.
Our searches for biogenesis have uncovered evidence of cyanobacteria in the Warrawoona
microfossils from Western Australia that indicate photosynthesis as early as 3.5 billion years
ago. Carbon isotope ratios have been used to identify evidence of organic material in the
18 Ibid. 19 Ibid. p. 64.20 Ibid. p. 66.21 Ibid. p. 67.
ancient rock formations of Isua, Greenland which date life to 3.85 billion years ago.22 Life seems
to have inhabited Earth in some form for at least 85 percent of its history, but where and how it
began is still a mystery.
There have been experiments done based on hypotheses of what conditions were like
on Earth when life got started. Working with Charles Darwin’s speculation that life got started
in a “warm little pond,” an American chemist, Harold Urey tried to recreate a “primordial soup”
of methane, hydrogen and ammonia gases along with water in a glass flask. He sealed the flask
and passed electric sparks through to simulate sunlight effects. Soon, he discovered his
primordial mix contained amino acids - the building blocks of proteins and the basic ingredients
to terrestrial life.23 It turns out that amino acids are not difficult to make – in fact they are
found to occur naturally in meteorites and in outer space – but the building blocks are a long
way from a finished structure. The amino acids must link together to form molecules known as
peptides, which then link together to become polypeptides and create proteins. While amino
acid production is a “downhill” process, (a thermodynamically favored spontaneous process
which lowers the energy of a system), peptide bonding requires work and does not happen
spontaneously – it is considered an “uphill” process. Though there were plenty of available
energy sources on the early Earth for generating organic molecules, while unregulated, this
same energy would also serve to destroy these fragile peptide chains. In an environment near
thermodynamic equilibrium, where molecules are jiggled about randomly, Davies reports that it
has been estimated, (by who is left unmentioned), that “left to its own devices, a concentrated
solution of amino acids would need a volume of fluid the size of the observable universe to go
against the thermodynamic tide and create a single small polypeptide spontaneously.”24
Additionally, it has come into question whether the early Earth had any of Urey’s predicted
gases in the atmosphere in the quantity or duration initially hypothesized.
American biochemist Sidney Fox has departed from thermodynamic equilibrium
conditions using a thermal energy flow of water conversion to steam to deal with the entropy
22 Ibid. p. 81.23 Ibid. p. 87.24 Ibid. p. 90.
issues. He created some long polypeptides called “proteinoids” which superficially look like
proteins except for one very important detail. Some of the most compelling evidence for a
universal common ancestor from which all other life evolved is the pattern of chirality, or
molecular handedness, which is found in all known living things.25 Fox’s “proteinoids” lack this
chirality, having an equal mixture of left and right amino acids.26 Real proteins are made
exclusively of left-handed amino acids.
Molecular biology has made great strides over the last few decades towards
“elucidating which molecules do what to which.” These functions have all been found to
operate according to ordinary physical forces and laws. Davies reminds us that it would be
wrong, however, to conclude that molecules are all that there is to life.
Life is a phenomenon associated with a whole society of specialized molecules, millions of them, cooperating in surprising and novel ways. No single molecule carries the spark of life, no chain of atoms alone constitutes an organism. Even DNA, the biological supermolecule, is not alive….Only within the context of a highly specific molecular milieu will a given molecule play its role in life.27
Cooperation at a global level cannot be explained in terms of the components alone; the sum is
greater than the parts. One of the primary functions that life must carry out is reproduction,
and this leads us into a chicken or the egg paradox when thinking about how individual
components could have developed separately.
“DNA contains the total information needed to build and operate the organism to which
it belongs. Viewed like this, life is just a string of four-letter words.”28 A very, very long string of
four-letter words. The DNA code of four-letter words for a simple bacterium could fill a
thousand page book, and human DNA would take up an entire library, but there is more to life
than coded information. DNA on its own is quite useless without proteins, especially proteins
in the form of enzymes. Proteins are the long chain molecules strung together from lots of
amino acids, and DNA has a “wish list” of all the recipes for making proteins that the organism
25 Ibid. p. 71, 73.26 Ibid. p. 91.27 Ibid. p. 92.28 Ibid. p. 104.
needs.29 DNA needs the cooperation of RNA – in the roles of mRNA (messenger) and tRNA
(transfer) to read these recipes and convey the information to the ribosome to carry out
protein production.
…the participating molecules are completely mindless. Collectively they may display systematic cooperation, as if to a plan, but individually they just career about. The molecular traffic within the cell is essentially chaotic, driven by chemical attraction and repulsion and continually agitated by thermal energy. Yet out of this blind chaos order emerges spontaneously.30
The translation of 64 possible codons into 20 amino acids is called the genetic code and aside
from a few recently discovered minor variations, this code is universal to all forms of known
life. Because this genetic code is both random and highly specific, along with amino acid
chirality, a common ancestor of all life is thought to have passed this genetic makeup through
billions of years of evolution.31
If each cell of an organism is such an elaborate self-sustaining community of molecules –
each being dependent on the others – then which part evolved first? Was it the information
storage house, (metaphorically, the software), DNA, or the rest of the working parts,
(metaphorically, the hardware)? Leslie Orgel hypothesized in the 1960’s that RNA may have
evolved prior to DNA and proteins. In the 1980s, research teams led by Thomas Cech and
Sidney Altman found that RNA is “chemically active enough to behave as a weak catalyst.”32
Biochemists were quick to spot that if RNA could somehow catalyze its own replication then life may have begun with a soup of RNA molecules acting both as genetic storehouses and, when folded into suitable three-dimensional shapes, as catalysts. Hardware and software would be present in the same group of molecules. This theory became known as the RNA world.33
In principle, Darwinian evolution really only needs replication, variation and selection, which at
a molecular level is termed “molecular evolution” or “molecular Darwinism.”
29 Ibid. p. 105.30 Ibid. p. 107.31 Ibid. p. 109.32 Ibid. p. 126.33 Ibid. p. 126.
Sol Spiegelman experimented with a small RNA virus named Q8. A virus is a strand of
DNA or RNA encased in a protein coat. Although viruses store genetic information, they cannot
replicate it on their own and must invade cells and hijack their reproduction apparatus to make
more viruses. Spiegelman, and later, Manfred Eigen, found fascinating results of spontaneous
synthesis of RNA strands from their basic building blocks, and a rapidly streamlined fast-
replicating mutation evolving when placed in special replication enzymes. Though these results
were exciting, the conclusion was reached that “without a trained organic chemist on hand to
supervise, nature would be struggling to make RNA from a dilute soup under any plausible
prebiotic conditions.”34 Additionally, genetic analysis “reveals that the genes coding for RNA
replication differ markedly in the three domains of life, suggesting that RNA replication was
refined sometime after the common ancestor lived.”35
If RNA didn’t come first, is it possible for proteins to self-replicate? Reza Ghadiri
recently found evidence that small peptide chains can self-replicate and the infamous mad cow
disease, or bovine spongiform encephalopathy, is caused by a fragment of protein that can
replicate and spread. Freeman Dyson, a physicist, argues that life had two origins – one for the
metaphorical hardware, another for the software. In this view, life arose from a sort of
symbiotic fusion creating early proto-cells lacking a genome but functioning with a rudimentary
form of selection and evolution “to get the thing started.”36 A growing population of distinct
cells would produce competition, and perhaps a parasitism: “the gene-less cells were invaded
by primitive nucleic acid replicators, and the two systems melded.”37 There are competing
hypotheses of where and how these proto-cells may have first formed. My favorite of these
hypotheses is described in a section Davies calls “Ascent from Hades.”
Geologists and astronomers are coming to realize that the early Earth was bombarded
by frequent collisions with comets, asteroids and other debris from the early solar system
formation. Many Mars sized planets are thought to have orbited the Sun, knocking into one
another. At some point one struck the Earth, plowed into the center and created the iron core,
34 Ibid. p. 131.35 Ibid. p. 132.36 Ibid. p. 134.37 Ibid. p. 135.
ripping the lighter mantle into space as orbiting debris which became our moon. Earth was
repeatedly struck:
..(B)odies from the outer solar system added a veneer of light rocky material to the Earth’s crust. More significantly, they also delivered vast quantities of water, enough to make the present oceans many times over. And along with water came many other volatile substances that the nascent Earth lacked, especially life-encouraging organics.38
The initial phase of bombardment gradually reduced in frequency after a few hundred million
years, but resumed again between 4 billion through 3.8 billion years ago. Though organic
material was delivered by these cosmic impacts, they also created global upheaval. At this time
the Earth likely had little atmosphere, but with the “influx of cometary material, the planet
became cloaked once more in a dense blanket of gases, augmented by volcanic vapors pouring
from the molten interior.”39 Extensive volcanism with a crushing atmosphere, deep oceans with
huge tides because the moon was closer and a very hot surface characterized the early Earth.
Norman Sleep and his colleagues at Stanford University analyze the effects of these
massive collisions and hypothesize that a few of these events were large enough to create
these conditions:
A huge volume of rock would be vaporized in a gigantic fireball that would spread rapidly around the planet, displacing the atmosphere and creating a global furnace. The surface temperature would soar to more than three thousand degrees Celsius, causing all the world’s oceans to boil dry, and melting rock to a depth of almost a kilometer. As the crushingly dense atmosphere of rock vapor and superheated steam slowly cooled over a period of a few months, it would start to rain molten-rock droplets. A full millennium would elapse before normal rain could begin, presaging a two-thousand-year downpour that would eventually replenish the oceans…40
Additionally, there would have been hundreds of impacts comparable to the ones that made
the major lunar features which would have been powerful enough to create a rock-vapor
blanket above the atmosphere, boil away the top forty meters of the ocean and trigger decades
of scalding rain, thoroughly sterilizing the Earth’s surface. And yet, due to the fossil record, we
hypothesize surface organisms were well established 3.8 billion years ago. Either life came
38 Ibid. p. 152.39 Ibid.40 Ibid. p. 159.
from space or got going very quickly as soon as conditions were at all bearable, and possibly,
life got started on Earth more than once. Kevin Maher and David Stevenson of Caltech have
reasoned that life could be said to have started when the time it took for self-replicating
organisms to emerge was less than the time between sterilizing impacts.41 If life took repeated
starts, it’s possible that the rock fossils from Greenland and Australia (shown in Figure 19.10
and 19.11 in our Biology class textbook) may not be ancestral to our form of life, but belonged
instead to an alternative biology destroyed by cosmic bombardment sterilization.
These violent early Earth scenarios have prompted scientists to look for life’s genesis
very deep below the ground. Most plants and animals today, even those adapted to the desert,
can only handle exposure to about 50 degrees Celsius/122 degrees Fahrenheit before our
proteins begin unraveling and no longer function. In recent decades, biologists found peculiar
bacteria that could comfortably live in temperatures of up to 70 degrees Celsius/158 degrees
Fahrenheit. These so named “thermophiles” use special stabilizing proteins with a heat-
resistant wax rather than normal fat for encasing their cell membranes. Since their discovery,
“hyperthermophiles” – those organisms that can live at 80 degrees Celsius or higher – have
been discovered in the hot springs of Yellowstone and around submarine volcanic “black
smoker” vents along the Galapagos Rift in the Pacific Ocean. About twenty different genera
have now been classified, many of which are Archaea. Especially deep in the sea, sunlight for
photosynthesis cannot be the source of the base of the food chain. We are most familiar with
plants as “autotrophs” – organisms that don’t eat organic matter but make biomass directly.
Autotrophs that make biomass using chemical energy instead of light energy have been named
“chemoautotrophs” or simply “chemotrophs.” Davies describes the discovery of true
chemotrophs as a pivotal event in the history of biology. “Biologists have long been aware that
topsoil contains bacteria and that limestone caves can be inhabited by specially adapted
organisms. But apart from these exceptions, the planet was pronounced dead from the ground
down.”42
41 Ibid. p. 160-161.42 Ibid. pg. 169.
In the 1920’s, geologist Edwin Bateson wondered why water extracted from oil fields
contained hydrogen sulfide and hypothesized that the gas might have been made by sulfate-
reducing bacteria living deep in the oil reservoirs. In the 1960’s, subterranean mineral deposits
were found to have fossil microbes and microbe traces. Concerns regarding nuclear waste
disposal and potential bacterial infiltration of oil reserves led to further investigative drilling
projects around the United States, especially in three kilometer deep Triassic sediment in
Virginia which revealed evidence of microbial life existing for at least 140 million years.43
Some core samples have been obtained with up to ten million bacteria per gram. It’s beginning to look as if the rocks beneath our feet are swarming with tiny life forms. Now that the existence of subterranean superbugs has sunk in, scientists are rushing to rewrite the textbooks. All sorts of geological oddities are being attributed to the activities of these unusual microbes. Acid-secreting bacteria, for example, can etch solid rock such as quartz, causing pitting and erosion…The networks of pores that enable oil to be extracted from sedimentary rocks might even owe their origin to these busy little organisms. If so, it opens up the lucrative prospect of harnessing superbugs to accelerate oil extraction.44
Studies in groundwater movement have found microbes at work in aquifers, with iron-
dissolving and sulfide-producing bacteria acting like miniscule lock-keepers “switching the flow
on and off according to their requirements.”45 Samples from ten sites in the Mediterranean Sea
and the Pacific and Atlantic oceans revealed microbes in all the samples, to a depth of 750
meters, and some have been preserved alive and cultured in the laboratory using a modified
pressure cooker.46 This data indicates that previously unknown subterranean microbes may
account for 10 percent or more of the Earth’s total biomass.
Many factors appear to be in favor of looking for Earth’s biogenesis at great depths. At
depth, it’s possible that microorganisms may have withstood the lethal meteor impacts and
surface sterilizations, as well as the intense ultraviolet radiation due to lack of the ozone layer.
The raw materials for life – hydrogen, methane, ammonia, hydrogen sulfide and other reducing
gases – would have been far more abundant at depth, especially in the vicinity of volcanic
43 Ibid. pg. 171.44 Ibid.45 Ibid.46 Ibid. p. 172.
vents. “Simulations of geothermally heated ocean crust yield far more organics than traditional
Miller-Urey experiments.”47 Sea-floor basalt is spongy and provides channels and cavities to
concentrate organic material and “(t)here is an enormous thermodynamic drive to form organic
compounds, as seawater and hydrothermal fluid, which are far from equilibrium, mix and move
toward a more stable state.”48 Everett Shock finds “the available energy is maximized at around
100-150 degrees Celsius, precisely the temperature range in which hyperthermophiles
live….Nowhere else on Earth is the connection between geochemical and biological processes
as profoundly evident as in hydrothermal systems.”49 Hydrothermophiles can tap into these
vast chemical and thermal energy reserves and gain energy by fabricating simple organic
compounds, fueling thermodynamically unfavorable reactions like peptide synthesis at rapid
rates. Shock estimates that in a typical vent location, life can exploit this thermodynamic
“bonanza” by creating biomass at a rate of 2.5 kg/hour.
The gene sequencing technique pioneered by Carl Woese can be used to reconstruct the
tree of life and model the evolutionary distances between different microbes. The Archaea
domain split away from the bacteria and eucarya possibly as early as 3.8 billion years ago.
While the later groups have undergone substantial genetic changes, the Archaea have changed
very little and it appears these “living fossils” most closely resemble the universal ancestral
organism.50 Additionally, those hyperthermophiles preferring the highest temperatures are
anerobes and do not require the oxygen that would have been absent from the early Earth
atmosphere. While surface conditions have changed immensely over time, the subsurface
conditions are thought to have remained largely the same, and it is possible that these
hyperthermophiles may have continuously dwelt there up to the present day, changing very
little from their ancient ancestors. That life ascended from the depths was originally proposed
in 1981 by Jack Corliss and popularized in 1992 by Tommy Gold. Initially met with skepticism,
this theory is gaining popularity across many disciplines.51
47 Ibid. p. 174.48 Ibid.49 Ibid.50 Ibid. p. 175-176.51 Ibid. pg. 178.
Since the discovery of chemotrophs, they are appearing everywhere we look. The
Archaea seem to divide naturally into three groups: thermophiles, halophiles and
methanogens, and bacteria exist using these forms of metabolisms as well. “The problem
about reconstructing the microbial base of the tree of life is that we have no idea what
organisms may remain undiscovered at this time.” Alerted to the presence of subterranean
methanogens after a hydrogen gas explosion during drilling, Todd Stevens and Jim McKinley
found that the rocks of a deep basalt layer were giving off hydrogen gas which is very explosive
in air. Methanogens combine hydrogen gas with dissolved carbon dioxide to make biomass,
and Stevens and McKinley were able to culture bacteria taken from a borehole at this site -
discovering a complex underground ecosystem in the Columbia River basalt layer. They have
described it as SLIME, or a Subsurface Lithoautotrophic Microbial Ecosystem, and hypothesize
there are many other locations of SLIME awaiting discovery. Certain locations in Oman, Japan
and California - where high concentrations of hydrogen seep to the surface - are prime
targets.52
Davies summarizes the superbug findings by saying the record of genes suggests that
the universal ancestor probably ate sulfur and lived at a temperature well above 100 degrees
Celsius deep beneath the Earth’s crust.53
The old name for sulfur is “brimstone,” a devilish substance associated with fiery
volcanoes and hell. It was a common element on the primeval Earth, especially in the
form of hydrogen sulfide. The central place of sulfur in the story of life’s origins is an
amusing irony. Not only was the real Eden most likely a Hadean inferno, it may also turn
out that life was created from brimstone!”54
However, this potential universal ancestor was not the first living thing – it appeared “with an
already sophisticated life form with complex features like coded protein synthesis… A long
evolutionary history must have preceded it.”55 Given the theorized early Earth conditions, life
may have started on the surface and been blasted by the meteoric impacts, having “their
particular branches of the tree of life abruptly truncated,”56 only allowing the high temperature
adaptive hyperthermophiles a niche to reside in. These “crude rock eaters” would lack
competition and easily radiate and adapt through mutant microbes to other niches as the
environment changed, branching into bacteria as early as 3.9 or 4 billion years ago, and then
later evolved lower temperature eukaryotes and their rapid diversification once photosynthesis
and oxygen appeared.
Davies continues in the next chapters to investigate the possibility of life on Mars, the
concept of panspermia (life “seeds” coming to Earth from space) and the potential of biological
genetic mixing between Mars and Earth. Studying dormant bacteria preservation and mortality
issues, Davies speculates:
Three or four billion years ago, when Mars resembled Earth, a Martian organism might well have found our planet very much like home, especially if it fell in the sea. Carried along by ocean currents, it might eventually have reached a deep ocean volcanic vent similar to its original habitat on Mars.57
Radiation during the space journey would be the greatest danger to the organic material, but
most of the radiation would not penetrate a rock. Meteor studies suggest potential frequent
landings of meteoric debris where the interior of the meteorite remains cold even when the
outer portion is melted by friction. The U.S. National Council’s Space Studies Board has stated
that “(s)urvival of microorganisms in a meterorite, where largely protected from radiation,
appears plausible. If microorganisms could be shown to survive conditions of ejection and
subsequent impact, there would be little reason to doubt that natural interplanetary transfer of
biota is possible….Such exchanges would have been particularly common early in the history of
the solar system when impact rates were much higher.”58 Davies lists a variety of reasons why
it would have very likely been easier for life to start, and to evolve, on Mars rather than Earth.
This leads us to speculate whether terrestrial life is descended from Mars, whether two forms
of life were in competition on Earth at some point, or if perhaps there was a symbiosis – like a
Martian mitochondria invading terrestrial bacteria resulting in mutual benefit.
Fully diving into the very exciting fields of astro-biology and astro-geology might well
double the length of this paper, and I have no desire to bore my reader beyond twenty or so
pages. But, we must consider that if rocks carrying signs of life can travel from Mars, such as
the ALH84001 meteorite that made such publicity in 1996, it seems plausible they could also
travel from Earth to Mars. If life had developed on Earth as early as the fossil evidence
suggests, then:
…copious quantities of life-bearing material will have been put into space by the many very large impacts that were still occurring 3.8 billion years ago. Some of this material will definitely have reached Mars, at a time when conditions there resembled those on Earth. It is therefore inevitable that life from Earth has reached Mars at some stage during its history. It also appears extremely likely that between 3.5 and 3.8 billion years ago conditions on Mars would have been suitable for transported terrestrial organisms to flourish.59
It is also possible that Earth life has traveled to the Moon – which once had a thick atmosphere,
volcanoes and water – or elsewhere in the solar system. Thomas Gold has speculated at least
ten moons or planets that may support life below the surface and believes that Earth may have
“just one strange branch of life” because conditions of surface life became possible.60 This
leads us to envision Earth’s biosphere potentially extending further into space than previously
thought.
For twenty years, Fred Hoyle and Chandra Wickramasinghe have hypothesized that
comets contain living organisms and have correlated support for this claim based on the
passage of comets and medical records of disease outbreaks. Analyzing the Justinian plague of
540 A.D. and E. coli, they suggest that various pandemics are extraterrestrial in origin. Davies
finds this claim audacious, but in my opinion, it is certainly one of the most thought provoking
hypotheses presented in the book, and it appears to be the subject of a science fiction movie
from the 1980’s. Additionally, Hoyle and Wickramasinghe support the steady-state theory –
59 Ibid. pg. 237.60 Ibid. pg. 240.
one which proposes that the universe, and life, has infinite age and therefore no beginning or
end. “Unless some law of nature limits the growth of intelligence and technology, or forbids
intelligent life forms from spreading across the universe though permitting simple organisms to
do so, it is hard to see how Hoyle’s dramatic proposals can be avoided.”61 While the stable-
state theory of everything existing forever is not logically inconsistent, it doesn’t provide much
explanation for biogenesis, the subject of Davies’s book.
So, is life governed by chance or necessity, or both (or neither)? This question seems to
be the driving force underlying all hypotheses of biogenesis. To illustrate, Davies uses the
example of the Earth’s orbit around the sun being determined by the elliptical form following
from Newton’s described laws of motion and gravitation. However, the specific size and speed
of the orbit is a product of complicated factors such as cosmic chance events of bombardment,
and therefore is partly chance. In contrast, the structure of a crystal is completely determined
by inter-atomic forces acting in necessity to form identical structures. Those believing that
chance figured prominently in biogenesis estimate that the infinitesimal probability that life
formed solely by random molecular shuffling precludes it from happening more than once in
the observable universe. Those believing that the emergence of life from nonliving chemicals
involves necessity, or lawfulness, hold that due to the nature of the universe, if life arose on
Earth it is likely to have done so in other places as well. This belief is called “biological
determinism” and Davies points out that it is more commonly held by chemists, physicists and
astronomers and much more rarely held by biologists.
Gary Steinman and Marian Cole did experiments in the 1960’s with amino acids which
indicated that molecules significant for life were made preferentially and suggested a sort of
“built-in predestination.”62 Others also find evidence that implies that “non-random self-
instruction infuses macromolecules with crucial biological information, paving the way for
life.”63 Darwin suggested “(t)he principle of life will hereafter be shown to be a part, or
consequence, of some general law.”64 But the orthodox paradigm, steeped in Darwinianism,
insists that biological evolution is a long series of meaningless, directionless accidents – with no
certain end or final cause.
NASA scientists are …making – tacitly – a huge and profound assumption about the nature of nature. They are saying, in effect, that the laws of the universe are cunningly contrived to coax life into being against the raw odds; that the mathematical principles of physics, in their elegant simplicity, somehow know in advance about life and its vast complexity. If life follows from the soup with causal dependability, the laws of nature encode a hidden subtext, a cosmic imperative, which tells them: Make Life! And, through life, its by-products: mind, knowledge, understanding. It means that the laws of the universe have engineered their own comprehension.65
To accept that atomic processes have a built in bias towards organisms would mean that the
laws of physics contain a blueprint for life.
Davies raises the point that by definition, the laws of physics that operate between
atoms and molecules are simple and general. They alone cannot lead to something highly
complex and highly specific. Genomes are essentially random sequences of base pairs and the
randomness is necessary for evolving information-rich molecules. Randomness contradicts the
claim that genes can be created by a predictable, simple law-like process. “A law is a way to
compress data algorithmically… ordinary laws just transform input data into output data. They
can shuffle information, but they can’t create it.”66 Davies argues that life goes in the opposite
direction and exists because it can free itself “from the shackles of non-random chemical
bonding” and circumvent what is chemically and thermodynamically natural. “Life opts out of
the strictures of chemistry by employing an information-control channel, freeing it to soar
above the clodlike blunderings of atomic interactions and create a new, emergent world of
autonomous agency.”67
In conclusion, Davies points out that he began this book research with the assumption
of “Darwinism all the way down” – that chance alone would provide molecular evolution
towards cellular life. He now finds this position insufficient. Going back to Schrodinger, and the
book that set this inquiry into motion, he recalls that Schrodinger was sufficiently puzzled by life
65 Ibid. pg. 246.66 Ibid. pg. 253.67 Ibid.
to suggest “a new type of physical law.”68 Davies finds two fields most promising for seeking
this new type of law – complexity theory and quantum mechanics.
These “laws” cannot be derived from the underlying laws of physics, because they are not physical laws in the usual sense. Instead, they arise from the logical structure of the system, and depend only indirectly on the physical forces involved… The hope of complexity theorists is that some sort of self-organizing processes could raise a physical system above a certain threshold of complexity at which point these new-style “complexity laws” would start to manifest themselves, bestowing on the system an unexpected effectiveness to self-organize and self-complexify… Under the bidding of such laws, the system might be rapidly directed towards life. If that is correct, it would mean that life is not so much written into the laws of physics as built into the logic of the universe.69
While normal physical laws shuffle information, complexity laws may be able to create
information, or draw it out of the environment and concentrate it onto a physical structure.
Blending molecular Darwinism with organizational complexity would amplify the selectivity in
the evolutionary process, leading to jumps rather than just incremental advance.
The subtleties of the quantum world offer another direction of inquiry. Because atoms
have wave-like and particle-like aspects, they are metaphorically software and hardware
entanglements, where information from observation has a “downward causative power.”70
Again, Davies recalls “What is Life?” Schrodinger, in describing the unit of heredity, called it an
“aperiodic crystal”- a molecular structure stable enough to retain its form but complex enough
to store a lot of information.71 “A normal periodic crystal has stability but low algorithmic-
information content.” An example of this would be fractal self-replicating patterns, which look
very complex, but require a minimum of the initial information which is simply repeated.
Aperiodicity arises because the sequence of bases is mostly random, and information-rich. In
recent years, chemists discovered a new sort of aperiodic crystal – which they’ve called a quasi-
crystal – which has an unusual five-fold symmetry which doesn’t repeat itself.
A normal periodic crystal can grow atom by atom, because it forms a regular repeating structure, but a quasi-crystal requires some sort of long-range organization to make sure
that the right bits fit in the right places. (Roger) Penrose thinks that subtle aspects of quantum mechanics, and even quantum gravity, may play a role in this geometric organization. Because of its five-fold symmetry, a quasi-crystal has very little information stored in its orientation, but an unlimited amount in its linear aperiodic sequence…. Like DNA, quasi-crystals seem at first sight to be “impossible objects” with enormous algorithmic complexity.72
Davies suggests that the study of quasi-crystals and quantum computations may shed light on
the organization and formation of complex physical structures with high information-storage
capacities.
In the end, Davies does not reject or accept “biological determinism” but asks us instead
to remember to consider the philosophical implications involved in allowing a teleological
assumption into our science. Personally, I feel ready to resume my reading of Schrodinger, now
that this Davies book has helped elucidate the issues Schrodinger brings up on page 3 of “What
is Life?” and to see where Schrodinger goes in working out the ethics and philosophical
implications of consciousness and Darwinian evolution theory in “Mind and Matter.” In
comparison, I thank Paul Davies for all the updated information on recent explorations of a
variety of fields and compelling, well-reasoned and easy to grasp language. I thank Schrodinger