Could life have evolved at random? The problem of giant molecules * The cell's
chemical weapons * Biology's junkyard mentality * Seeing through the primordial
soup * The blind alley of Darwinism
A generation or more ago a profound disservice was done to popular thought by the
notion that a horde of monkeys thumping away on typewriters could eventually arrive at
the plays of Shakespeare. This idea is wrong, so wrong that one has to wonder how it
came to be broadcast so widely. The answer I think is that scientists wanted to believe that
anything at all, even the origin of life, could happen by chance, if only chance operated on
a big enough scale. This is the obvious error, for the whole Universe observed by
astronomers would not be remotely large enough to hold the horde of monkeys needed to
write even one scene from one Shakespeare play, or to hold their typewriters, and
certainly not the wastepaper baskets needed for throwing out the volumes of rubbish
which the monkeys would type. The striking point is that the only practicable way for the
Universe to produce the plays of Shakespeare was through the existence of life producing
Shakespeare himself.
Despite this, the entire structure of orthodox biology still holds that life arose at
random. Yet as biochemists discover more and more about the awesome complexity of
life, it is apparent that the chances of it originating by accident are so minute that they can
be completely ruled out. Life cannot have arisen by chance.
Life's improbable building blocks
The probability of life appearing spontaneously on Earth is so small that it is very
difficult to grasp without comparing it with something more familiar. Imagine a
blindfolded person trying to solve the recently fashionable Rubik cube. Since he can't see
the results of his moves, they must all be at random. He has no way of knowing whether
he is getting nearer the solution or whether he is scrambling the cube still further. One
would be inclined to say that moving the faces at random would "never" achieve a
solution. Strictly speaking, "never" is wrong, however. If our blindfolded subject were to
make one random move every second, it would take him on average three hundred times
the age of the Earth, 1,350 billion years, to solve the cube. The chance against each move
producing perfect colour matching for all the cube's faces is about
50,000,000,000,000,000,000 to 1.
These odds are roughly the same as you could give to the idea of just one of our body's
proteins having evolved randomly, by chance. However, we use about 200,000 types of
protein in our cells. If the odds against the random creation of one protein are the same as
those against a random solution of the Rubik cube, then the odds against the random
creation of all 200,000 are almost unimaginably vast.
Proteins are among the most complicated chemical components of the body. Each
performs specific tasks- for example forming the materials which give the body its
structure, carrying substances from one place to another, or acting as keys which turn
biochemical reactions on and off. Yet all these 200,000 widely different proteins are made
up of the same basic ingredients, rather simple substances known as amino acids,
arranged in chains in precise sequences.
We need not dwell on the detailed structure of amino acids. It is sufficient to think of
each one as a bead, with a different colour for each kind. A protein is then like a string of
coloured beads, with the exact interspersing of the colours determining its shape and
function. A typical protein is made up of a chain about one hundred beads long, containing
at the most twenty different colours.
The operation of a successful life-form is like a successful military operation-both have
two sharply distinct requirements. Adequate hardware in the form of weapons is essential,
and adequate software in the form of strategy is also needed. Many of the 200,000
proteins used in our cells- he protein "keys"- are the software of the cell. The essence of a
key is that one pattern will provide a key that is just as effective as any other. So to
calculate fairly the probability of life arising by chance we shall ignore all the proteins
which might be keys, and instead concentrate on the minority which have shapes that are
vitally important. For these special proteins, the enzymes, the correct string of amino acid
"beads" is essential, because alterations can make them useless.
The molecular matchmakers
Enzymes are the equivalent of military hardware. They are protein weapons used by a
cell in its battle for survival against the physical environment. Their function is to act as
intermediaries between other biochemicals and to catalyze or speed up processes which
provide both nutrients and energy for life. Left to themselves most chemical reactions of
importance in biology would proceed so slowly that life would be impossible. The food we
eat would be useless to us because its chemical components and energy could not be
released fast enough to keep us alive. Enzymes speed these processes up enormously.
In total there are perhaps 2,000 such enzymes, and their structures are basically the
same across the whole of the living world- an enzyme from a bacterium can be used in the
cell of a man. The chance of finding each individual enzyme by stringing together amino
acid beads at random is again like the Rubik cube being solved by a blindfolded person.
Although the chance of finding all the enzymes, 2,000 of them, by random processes is not
nearly as small as the chance of finding the whole 200,000 proteins on which life depends,
the chance is still exceedingly minute. Call it x to I against. If you started to write x out in
longhand form, beginning with the digit I and adding zeros, you would have a few hours
of work ahead- 1,000,000,000,000,000,000,000,000,000,000,000, 000, 000, 000, 000,
000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000... and so on for about forty pages,
some 40,000 zeros in all. It is about the same as the chance of throwing an uninterrupted
sequence of 50,000 sixes with unbiased dice! This is a crucial statistic, because it seems
that without these 2,000 enzymes being formed in exactly the correct way, complex living
organisms simply could not operate.
Although the probability of the random origin of "just" these 2,000 enzymes is
minuscule, there are many scientists who do not see this calculation as dismissing the idea
that life arose by chance. Like all statistics, probabilities of this type are open to different
interpretations. One important point which has to be established is the context in which we
are talking.
Were there many ways in which life could have evolved? The argument I have used
above would be weakened if the origin of life as it is found on Earth happened to be just
one highly improbable event taken out of a vast number of potentially similar events.
Imagine a golfer playing a tee-shot for example. Suppose he makes a long drive and his
ball lands far down the fairway and comes to rest on a particular tuft of grass. The chance
of the ball arriving on this particular spot was tiny. However, there is a huge number of
similar places that the ball could have landed on, and the chance of the ball arriving
somewhere on the fairway (assuming a reasonably proficient player) was almost a
certainty.
Could it be that this was what the origin of life was like? The odds of finding life with
our basic form of chemistry might be exceedingly small, but could there not be- like all the
points on the fairway- a vast number of other kinds of biology, which we know nothing
about, each with its own very small chance of becoming established on a planet like the
Earth?
I think not. The reason why this question must be answered negatively, and why we
must therefore abandon this way of avoiding the startling conclusion that life cannot have
arisen by chance, is that the chemical reactions catalyzed by the 2,000 enzymes are
fundamental to the basic chemistry of the carbon atom itself. Despite its complexity, our
biochemistry may well be the simplest form possible. Take, for example, sugars, the main
energy source of life. These are built up from the two commonest molecules in the
Universe, the molecules of hydrogen and carbon monoxide. Thus the enzymes we use to
unlock the energy content of sugars are engaged in processes which are central to the
chemical content of the whole Universe. Hence there is nothing hole-in-the- corner about
our terrestrial system. There are not vast billions of other equally likely systems. Indeed it
is to be doubted whether there is even one other system that operates so fundamentally on
molecules composed of the commonest atoms in the Universe, the atoms of carbon,
oxygen, nitrogen and hydrogen.
The idea of the primordial soup
The popular idea that life could have arisen spontaneously on Earth dates back to
experiments that caught the public imagination earlier this century. If you stir up simple
non- organic molecules like water, ammonia, methane, carbon dioxide and hydrogen
cyanide with almost any form of intense energy, ultraviolet light for instance, some of the
molecules reassemble themselves into amino acids, a result demonstrated about thirty
years ago by Stanley Miller and Harold Urey. The amino acids, the individual building
blocks of proteins can therefore be produced by natural means. But this is far from
proving that life could have evolved in this way. No one has shown that the correct
arrangements of amino acids, like the orderings in enzymes, can be produced by this
method. No evidence for this huge jump in complexity has ever been found, nor in my
opinion will it be.
Nevertheless, many scientists have made this leap-from the formation of individual
amino acids to the random formation of whole chains of amino acids like enzymes-in spite
of the obviously huge odds against such an event having ever taken place on the Earth,
and this quite unjustified conclusion has stuck.
In a popular lecture I once unflatteringly described the thinking of these scientists as a
"junkyard mentality". Since this reference became widely and not quite accurately quoted I
will repeat it here. A junkyard contains all the bits and pieces of a Boeing 747,
dismembered and in disarray. A whirlwind happens to blow through the yard. What is the
chance that after its passage a fully assembled 747, ready to fly, will be found standing
there? So small as to be negligible, even if a tornado were to blow through enough
junkyards to fill the whole Universe.
The primordial soup exposed
So how do those who claim that life originated in an organic soup imagine that complex
life developed? Their argument, weak it seems to me, goes as follows. Suppose that on the
early Earth two or three very primitive enzymes appear and come together in a primordial
soup of amino acids formed at random, an occurrence perhaps not beyond the bounds of
possibility. The clump of enzymes then tours around the soup, picking up other potential
enzymes as and when they happen to arise by chance. Some commentators envisage the
clump reproducing itself a large number of times, actually becoming a "living" group of
molecules.
This is a very unlikely supposition. On the Earth today, even the most complex viruses,
which contain a considerable number of protein molecules, are nevertheless unable to
reproduce themselves in any form of non-living organic soup. Besides which a false
plausibility has been generated, not by scientific argument, but by a play on words. In
effect, what has been done is to describe how we ourselves would go about collecting up a
packet of needles which had become scattered throughout a haystack, using our eyes and
brains to distinguish the needles from the hay. How, for instance, would the enzyme clump
distinguish an exceedingly infrequent useful enzyme from the overwhelming majority of
useless chains of amino acids? The one potential enzyme would be so infrequent that the
aggregate might have to encounter 50,000,000,000,000,000,000 useless chains before
meeting a suitable one. In effect, talk of a primitive aggregate collecting up potential
enzymes really implies the operation of an intelligence, an intelligence which by
distinguishing potential enzymes possesses powers of judgment. Since this conclusion is
exactly what those who put forward this argument are anxious to avoid, their position is
absurd.
To press the matter further, if there were a basic principle of matter which somehow
drove organic systems toward life, its existence should easily be demonstrable in the
laboratory. One could, for instance, take a swimming bath to represent the primordial
soup. Fill it with any chemicals of a non-biological nature you please. Pump any gases
over it, or through it, you please, and shine any kind of radiation on it that takes your
fancy. Let the experiment proceed for a year
and see how many of those 2,000 enzymes have appeared in the bath. I will give the
answer, and so save the time and trouble and expense of actually doing the experiment.
You would find nothing at all, except possibly for a tarry sludge composed of amino acids
and other simple organic chemicals. How can I be so confident of this statement? Well, if
it were otherwise, the experiment would long since have been done and would be well
known and famous throughout the world. The cost of it would be trivial compared to the
cost of landing a man on the Moon.
I can imagine someone saying: "Wait a minute! The primordial soup in the early history of
the Earth was much bigger than a swimming bath. Perhaps it was even as big as the
ocean". Very well, let us reduce the amount of chemical complexity to be accumulated in
the swimming bath so as to allow for its smaller volume. The odds against producing the
2,000 enzymes is the number we have seen before, the number which occupies about forty
pages with its zeros. Reducing this huge array of zeros pro rata to allow for the smaller
volume of the swimming bath does improve the odds, but only to the extent of removing
about half the last line on the last of the forty pages.
One might also try arguing that the process gathered momentum in the supposed
primordial soup. A critic might say: "You have allowed only for a single year in your
experiment. Because the process accelerates this is not long enough for anything to show
up. You should allow a thousand million years". In answer it is easy to prove that even the
most enormous acceleration would not remove more than a fraction of the last of the forty
pages, leaving more than thirty-nine pages of zeros, still an enormous number. If
acceleration were so important, the swimming bath should be found to contain many
proteins with amino acid sequences well on the way towards those which appear in
biology. It should easily be recognizable as a new biological world- in as little as a minute
or two it should have the obvious aspects of such a system, even if one did the experiment
in a test-tube instead of a swimming bath,
In short there is not a shred of objective evidence to support the hypothesis that life
began in an organic soup here on the Earth. Indeed, Francis Crick, who shared a Nobel
prize for the discovery of the structure of DNA, is one biophysicist who finds this theory
unconvincing. So why do biologists indulge in unsubstantiated fantasies in order to deny
what is so patently obvious, that the 200,000 amino acid chains, and hence life, did not
appear by chance?
The answer lies in a theory developed over a century ago, which sought to explain the
development of life as an inevitable product of the purely local natural processes. Its
author, Charles Darwin, hesitated to challenge the church's doctrine on the creation, and
publicly at least did not trace the implications of his ideas back to their bearing on the
origin of life. However, he privately suggested that life itself may have been produced in
"some warm little pond", and to this day his followers have sought to explain the origin of
terrestrial life in terms of a process of chemical evolution from the primordial soup. But,
as we have seen, this simply does not fit the facts. In pre-Copernican days, the Earth was
thought erroneously to be the geometrical and physical centre of the Universe. Nowadays,
in seemingly respectable science the Earth is taken to be the biological centre of the
Universe, an almost incredible repetition of the previous error.