_An Evolutionary Experiment_
Questions are often made unnecessarily difficult by their being
expressed in an abstract or theoretical form, and instead of asking
What is life? it will be more valuable to put forward a practical issue
for discussion: Could an infinitely wise physicist order the necessary
chemicals to-day, and to-morrow put together a synthetic man? If not,
why not? What are we really up against, that seems to put some aspects
of life beyond our control?
Let us watch this ambitious physicist as he enters his laboratory.
He has started quite easily and has in a moment prepared some simple
molecules from their elements. Now he has completed the first colloid
that he will require, and is starting on his first organic synthesis.
But his infinite wisdom does not give him eternity within a minute,
and we notice that he is getting on more slowly. While the actual
combination of the first molecules took only about a thousandth of a
second, once he had the apparatus ready, the simplest colloid took
about a second. The organic colloid has taken him about a minute; it
seems that nature won’t work faster than that. She has her own rhythm
and won’t be rushed. If we wait patiently till the end of the day our
friend may have his first speck of protoplasm, and all the skill in the
world would only have helped him to make more of it, not to have got
any further in his game of evolution.
But look at him now! He is making a hasty calculation as though he had
just realized some great secret of nature, and knew that he could never
create his homunculus. We look over his shoulder and read:
_Estimated minimum time required by the synthetic processes of nature
to attain various evolutionary stages._
Starting from the Minimum
elements, to Time
Simple inorganic compound 1/1000 sec.
Simple colloid 1 sec.
Protein 1 hour
Primitive protoplasm 1 month
Simplest uni-cellular organism 10 years
Flagellate 1,000 years
Mammal, including _Homo sapiens_ 1,000,000 years
This highly speculative estimate is based on suggestive facts. A
certain amount of time is necessary for two atoms to approach one
another and form a molecule. The time required will be greater if many
atoms have to settle down together into some special arrangement. For
instance, the metal silver is normally crystalline, but if silver
vapour is condensed too quickly the atoms will not have time to
arrange themselves, and it is found that they pile up anyhow into an
amorphous mass.
Colloidal processes require even longer periods, because great clumsy
molecules have to arrange themselves on the surface of the colloidal
particles. In elementary forms of protoplasm the molecular patterns
are still more complex, and yet more time must be necessary to get the
molecules properly adjusted.
It is probable that only our ignorance prevents us from building up
protoplasm, but that we shall require rapidly increasing amounts of
time for each successive stage of evolution. This will certainly be
the case when we have reached organisms which can only be rendered
more complex by controlling their environment while they reproduce
themselves for many generations. A higher organism cannot be built up
directly; the molecular arrangements in its body can only be reached
through the synthesis of some simple form of life which must then be
allowed to evolve through countless generations. Organic heredity
resides in molecular patterns which can only be built up by this very
slow process of repeated reproduction. Thus it is _shortage of time_
that our ambitious scientist is up against in his haste to create a
homunculus. Only the synthetic alchemy of time can build up organisms,
each bearing within itself a long heredity.
The estimates given for the minimum time required in each case are
about a thousandth of the actual time taken in a laboratory experiment
or in the history of evolution as known from geological records. It may
have taken a million years or more for the first mobile cells to have
developed from inorganic materials and a thousand million years for the
mammals. Yet perhaps these processes might have gone on more quickly.
The times given are mere suggestions of a minimum time which may be
necessary under ideal conditions. We waste a lot of time adjusting
the apparatus in a laboratory experiment, and in evolution there may
have been stationary periods with little or no new development. But it
seems likely that when we know more about it we shall discover that a
certain time is required for the formation of organic systems of given
complexity. In this sense we may say that then human spermatozoon and
ovum carry within them the synthesis of at least a million years.
Only an International Institute of Evolutionary Research under the
most stable of Leagues of Nations could hope to create an artificial
man, and even then man could hardly take the credit, for Time would
have done more than man. But with sufficient consistency of purpose
man could do this, provided he learnt how to make use of every moment
of the creative power of time, and never made a slip by which the
accumulated treasure of the years (i.e. heredity) might be broken. How
man would learn to value life, and how profoundly such an experiment
might alter his view of human beings, each one a priceless miracle,
fruit of a million years!
In twenty years’ time scientific knowledge will be adequate for the
beginning of this giant task, and we shall be subscribing our guineas
for the foundation of the Institute. Time has created man; man may use
time to create man once more. With a million years ahead of us before
we reach the sensitive mammals, we need hardly fear criticism from the
Society for the Prevention of Cruelty to Animals. We are simply going
to allow life to evolve itself under ideal conditions with Switzerland
as the State for Evolutionary Research.
It may happen that under such perfect conditions life will evolve more
swiftly than it did on this rough-and-ready planet. But equally well
we--or rather our descendants--may find that the Darwinian struggle for
survival is essential for evolution, and then the nations would have to
debate on the morals of reproducing the ‘cruelty of nature’ inside the
World’s Evolutionary Zoo. Perhaps a wrathful god will seek to punish
mankind for attempting to build this ladder to the secret of life, this
modern Tower of Babel, and amuse himself by watching the community of
scientists stricken by a plague of inconsistency amongst their weights
and measures.
The possibilities of such grand schemes have to be taken seriously. We
are now highly self-conscious beings with a tremendous technique for
research. Men with genuine creative imagination who reverence life must
shoulder the responsibilities of the twentieth-century consciousness,
and use scientific technique for creative not life-destroying purposes.
One can imagine a growing fraction of the interest now given to
war, other people’s adultery, and greyhound racing, turned towards
Switzerland, whence at critical moments wireless bulletins would
announce that the first amoeba had just successfully taken nourishment.
If we wish it, the future of science can be such as to recompense for
its recent occupation with gunpowder. Governments would be powerless
to make war if the physicists refused to make the guns and the Royal
Society called upon scientists to go on strike until each war crisis
had been settled by arbitration.
The problem of life may be seen in a new light if the speculations of
the last section are accepted and we assume that a definite period
of time is necessary for the building up of any living organism. For
if this is so the laws which govern life must involve the age of the
organism since some definite moment in its history. We might choose for
this moment the instant when the parent spermatozoon entered the ovum
in the case of a higher organism, or in the evolutionary experiment
just described the age might be reckoned from the moment when the first
elementary chemicals were combined into molecules. The point is that
this whole evolutionary process must be described by laws which take
into account the age of the system under consideration.
Let us take a very simple, indeed the simplest possible, example.
If two hydrogen atoms having just the correct total energy for the
formation of a hydrogen molecule have approached one another and
combined, the law describing what has happened must indicate that at
a definite moment the combination was complete and the process at an
end. This is an example of an irreversible process, since the molecule
does not _spontaneously_ break up again. Moreover, the mathematical
formulation of this process must include the definite age of the system
at which the process was complete, this age being measured from some
selected initial moment.
This process provides an interesting limitation to a principle put
forward by Maxwell as the basis of physical science. He suggested that
the laws of physics must be considered to be eternal and unchanging and
that therefore they must be expressed in a form which does not contain
the time explicitly. This means that for physical laws there can be no
difference between to-day and to-morrow. The laws are concerned with
small changes which systems undergo in small time intervals, and need
not express any fundamental distinction between one moment and another.
Such laws cannot express the fact that anything sudden ever occurs
which makes an essential change in the system as when two systems
become one, or when one system breaks up into two. The laws of organic
growth or the evolution of individual systems must display the fact
that at a certain age of the system special things happen, such as the
combination of two hydrogen atoms, or the attainment of maturity by an
organism. Maxwell’s principle puts a limitation on the form of physical
laws which precisely eliminates the laws that would be appropriate for
organisms. But there is no reason why a broader physics should not try
to frame this new type of law that would be applicable to the history
and development of individual systems, and it is probable that if this
could be done the reversible laws of Newton, Maxwell, and Einstein
would appear as approximations which were valid when nothing of special
interest was happening, i.e. when only spatial movements were involved
without synthesis, disintegration or the emission of light.
Laws of the Newtonian type which Maxwell had in mind assume that
one can adequately describe the present state of a system without
specifying its past history. But we cannot say anything very precise
about the inside of a living organism, and it is found far more
efficient to describe what is known of its past history. We do not try
to say where atoms are in an organism; instead we mention its species,
age, etc. Organisms might be defined as systems whose future behaviour
is more easily estimated from their past history than from what can be
known about their immediate internal structure. The most convenient
formulation of organic laws will therefore be expressed in terms of
the age of the organism and take account of how its life has been
spent. These laws are necessarily irreversible, since the assimilation
of oxygen or food is always going on in a manner which can never be
reversed. Life is like a function which must always alter in one
direction; when this development ceases life has disappeared.
The contrast of living and dead now appears less important than the
following classification of natural processes:
1. Processes which are reversible and whose laws can be expressed
independently of the age of the system, e.g. gravitational and
mechanical motions which do not involve light or heat.
2. Processes which are irreversible, the laws being best expressed in
terms of the total time which has passed since some initial state,
e.g. chemical combination, growth, evolution, radioactivity, and all
changes involving light or heat.
Physics has always asserted that processes of the first type were
fundamental in nature, and astronomy provided the ideal example in
planetary motion. It was this assertion that gave rise to the essential
issue behind the conflict of mechanism and vitalism. But if Born is
right, and the fundamental atomic processes are irreversible, then
the situation is completely altered. There is no longer a question
of life being an arbitrary irruption in a world of mechanical law,
since the laws of gravitation and mechanics must then be looked on as
the limiting case, when the irreversibility is vanishingly small, of
a whole series of irreversible processes which constitute the most
important examples of the fundamental order in nature. This series
would include the atomic processes connected with heat, light, and
electricity, chemical combination, colloidal effects, organic growth
and evolution, and the highly co-ordinated electrical processes which
form the physiological basis of consciousness.
If this view is correct the atomic processes of radiation and chemical
combination should be just what the biologist needs to build up
organisms. Instead of a chaos of little particles obeying inverse
square laws, the modern physicist offers to the biologist a new kind of
atom with electrical and magnetic properties which cause it to build
up stable compounds.
The biologist may reply: “Yes, but organisms have four chief
characteristics, their behaviour is irreversible, and displays
growth, memory, and purposiveness. If you tell me that your atoms
obey irreversible laws, so much the better, because my organisms
certainly do. But your crystals grow very differently from my cells and
organisms, and you can’t explain away the apparent purposiveness of all
life.”
To which the physicist may answer: “Suppose that two hydrogen atoms are
some distance apart with the total energy necessary to make a molecule.
If they begin to move towards one another under some attractive
influence which they exert we display no surprise. But they are moving
towards a final end, which is an end, even though they are of course
unconscious of it; and provided that nothing interferes they will reach
one another, form a molecule, and the process will be consummated.
The atoms move under an irresistible law of attraction towards a final
condition which is unavoidable unless outside influences prevent
it. The system of the two atoms develops necessarily towards a
consummation, and the process has in this sense a teleological quality,
though this need not mean that any god or man had consciously planned
the end for these particular hydrogen atoms.
“This quality was not present in Newton’s law of gravitation precisely
because it failed to say what happens at the end of any process, for
instance when a meteorite hits the earth. Newtonian laws avoid the
responsibility of dealing with all the exciting events, like the
wedding of the atoms or the death of the meteorite. On the other hand
it appears probable that all irreversible laws can be interpreted as
leading either from or to some critical end condition. Thus all heat
processes tend towards an approximate uniformity of temperature, and
chemical reactions also move towards a final condition.
“Such systems as these display the rudiments of unconscious purpose.
One must imagine these systems made much more complex so that it takes
a long time and considerable nourishment before their unconscious
purpose is fulfilled, whether this be the instinctive reproduction of
their kind or any other biological function.”
“Maybe. I like the unconscious purpose which you have revealed in
irreversible physics, because I am troubled by colleagues who see
conscious mind everywhere.
“But if I grant that your view of the atom, and hence of molecules
and colloids, allows me two of the four features I find in life, i.e.
irreversibility and unconscious purpose, you have still to deal with
growth and organic memory.”
“Yes. Growth and memory are things that physics has as yet little
to say about. But we have at any rate reduced the problem of life
to smaller proportions. It is no longer the question what is
life? but, how do colloidal processes build themselves up into
continuously-active, developing systems which can react to their
surroundings so that some distant condition can ultimately be attained?
This is a much less difficult question. Moreover, since the problem of
radiation underlies all the chemical processes which are associated
with the maintenance of life, we may expect considerable assistance
when physics has cleared up this crucial problem.”