November 1997
Gaia and Selfish Genes:Differing Perspectives on Life
By ERIC STRONG
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rom the dawn of human consciousness, our minds have been plagued by questions of our existence.
Who are we? How did we come to be here on Earth? The debates surrounding these questions have
permeated our societies from their beginnings in all areas of thought including religion, philosophy,
and most recently, science. It is somehow ironic however, that although these are among the oldest
of all questions, they are still the farthest from a resolution. Even in the late 20th century, when we
find ourselves in a time of great scientific discovery and technological advances, the scientific
community is far from a consensus concerning our origins. Many familiar with the debate
categorize it as a simple reductionist vs. holistic argument. The "reductionist" side is represented by
Richard Dawkins in his book, The Selfish Gene, in which he argues that the gene is the
fundamental unit of natural selection. On the opposite side of the spectrum stands the "holist" side
led by James Lovelock and his alternate view of life's origins as outlined in The Ages of
Gaia, where he claims that our entire planet evolves as a whole, as if it were a single organism.
The disagreement between these two sides is a complex one - the result of not only differing
scientific views, but also of differing ideas of language and philosophy. Although resolution of this
conflict may seem impossible without the complete surrender of one opponent, I contend that such a
resolution is quite possible, as the holists and reductionists are merely viewing the same processes of
life from differeing, but not mutually exclusive, perspectives.
Before we can approach the disagreement between Lovelock and Dawkins, we must first understand
each position individually. Lovelock describes The Ages of Gaia as "a biography of the
living Earth". The book is a roughly chronological view of the history of our planet and the
evolution of life as seen by Gaia. Gaia is a difficult concept to define specifically, as even Lovelock
will admit. It can be seen as a kind of superorganism where both the living and non-living parts of
our planet exist as a "self-regulating system that keeps itself in a constant state". (Kerr, p.393) Gaia
theory suggests that life is necessary to keep the planet's climate and chemical composition in its
current state of homeostasis for long periods of time until an external force interrupts it, at which
point it will jump suddenly to a new stable state. In his book's introduction, Lovelock claims that
"this book is neither holistic nor reductionist" (Lovelock, p.13) - a statement that is immediately
called into question by the following section found earlier in the introduction:
| Why run the Earth and life sciences together? I would ask, why have they
been torn apart by the ruthless dissection of science into separate and blinkered disciplines? ...the
evolution of the organisms and the evolution of the rocks need no longer be regarded as separate
sciences to be studied in separate buildings of the university. (Lovelock,
p.11) | |
This statement makes it clear that Lovelock's view is quite holistic in nature. He believes that
geology, climatology, and biology all belong to the same science - one he calls geophysiology, the
study of the living and non-living Earth as a single system.
Lovelock uses several examples to demonstrate that the living and non-living of our planet are only
components of a larger, inseparable whole. The first of these deals with the concentration of carbon
dioxide in our atmosphere. During the Earth's distant past, the atmosphere contained much more
carbon dioxide than at present. This was an essential requirement for the evolution of life in that
high CO2 levels helped the Earth retain a greater percentage of incident solar energy, thus helping to
keep the climate warm during a time when the Sun was significantly less luminous than it is today.
However, as the Sun brightened, the Earth needed some kind of mechanism to rid itself of CO2 in
order to prevent the planet from becoming a steamy inferno. Lovelock contends that only living
organisms could achieve this in a Gaian manner and stabilize the surface temperature at a level more
favorable for life. Much of the atmosphere's previous CO2 is now locked away in limestone, the
product of mass deposits of calcium carbonate shells.
Another example Lovelock uses is the chemical disequalibrium of the Earth's atmosphere. Whereas
Venus and Mars, planets devoid of life, have atmospheres dominated by carbon dioxide, Earth's
atmosphere is dominated by nitrogen and oxygen, two chemically reactive compounds. Basic
chemistry would predict that if left alone for billions of years, air on Earth would be transformed
into a composition closer to that of its planetary neighbors. Relatively unstable gases such as nitrous
oxide and methane should also not be expected to exist in our atmosphere. However, they do, and
Lovelock's answer to this puzzle is life. Living organisms have helped maintain the chemically
unfavorable composition of Earth's atmosphere through biochemical processes.
One last important example used by Lovelock is that of Daisyworld. Daisyworld is an imaginary
planet, a model simulated on a computer by Lovelock, whose purpose is to demonstrate how the
living components of a planet can keep the planet in a chemical and thermodynamic steady-state,
even when acted on by outside forces. In its simplest form, Daisyworld is populated by only two
species of daises, one dark and one white, whose relative abundances are affected by the overall
luminosity of an ever brightening Sun, but who then in turn, help to maintain a steady temperature
on the planet's surface. The complexity of this model can be increased to include many more species
of different trophic levels with similar results, thus showing that a planet's biota can regulate its
atmospheric content, the main thesis of Gaia theory.
In great contrast to Lovelock however, stands Richard Dawkins. In The Selfish Gene,
Dawkins presents a very different view of life, one in which the superorganism Gaia is not in control
of evolution and life, but rather, individual genes are in control. Genes are grouped together in a
more general molecule, the replicator. Dawkins contends that replicators - molecules with ability to
self-replicate - were the first form of life. Cells and organisms, which he calls survival machines,
exist only to aid the replicators in their continued propagation. Because the existence of cells and
individuals is only secondary to the existence of genes, the gene is the primary unit of natural
selection.
This is far different from the more holistic group-selection theory of evolution that argues that the
propagation of individual genes is insignificant to the tendancy for the continued propagation of the
species as a whole. Dawkins shows why this approach is incorrect in two ways in order to support
his own theory. First, he argues that in a population of purely altruistic individuals who all work to
better the species, a mutant, rebellious individual could arise who exploits the altruism of his
neighbors. Thus, he increases his chances of survival while decreasing the chances of survival of
every other individual in the population. It is easy to see how this will inevitably lead to a
population full of exploiting individuals of only selfish intentions, destroying whatever pure altruism
originally existed. Dawkins' second argument against group selection points out that the division of
animals into species is a completely arbitrary one. He writes,
| If selection goes on between groups within a species, and
between species, why should it not also go on between larger groupings? Species are grouped into genera,
genera into orders, and orders into classes. Lions and antelopes are both members of the class Mammalia,
as are we. Should we then expect lions to refrain from killing antelopes, "for the good of the mammals"?
(Dawkins, p.10) | |
Without an absolute, non-arbitrary division between where group-selection should and should not
act, the only alternative we are left with is one which goes down to the most fundamental level, one
in which selectoin only acts directly on individual genes.
Throughout The Selfish Gene, Dawkins not only cites specific examples from the natural
world as evidence of his ideas, but he also refers to several mathematical concepts to serve as models
for how the Selfish Gene theory might operate. He uses the classic example of Prisoner's Dilemma
to demonstrate a possible mechanism behind what at first appears to be true altruism, but is later
shown to be a form of selfishness in disguise. Dawkins also uses the idea of the evolutionary stable
strategy (ESS) in his explanation of multiple facets of the evolution of social interaction, from
altruism to aggression to sexual relationships. Prisoner's Dilemma and the ESS serve a similar
function to Dawkins as Daisyworld does to Lovelock. They are part of mathematical models to
show how Selfish Gene theory might work in the real world of competing genes and their survival
machines.
Not surprisingly, the reductionist supporters of Dawkins' Selfish Gene approach to evolution have
voiced sharp criticism of Lovelock's Gaia. The most frequent o these criticisms is that Gaia theory is
teleological. For a scientific theory or idea, to be labeled teleological is just about the worst
response it can receive. Perhaps Lovelock describes it best himself in writing that for the Gaia
hypothesis to be branded teleological was "a final condemnation." He continues, "Teleogical
explanations, in academe, are a sin against the holy spirit of scientific rationality ; they deny the
objectivity of Nature." (Lovelock, p.32) It is often pointed out that the organisms of the Earth could
not get together and hold a conference to decide at what temperature to keep the planet's surface.
People also debate Lovelock's assumption that the existence of a homeostatic Earth fit for life is so
unlikely that there must be some mechanism other than simple luck involved. If it just so happens
that the Earth is maintained at a certain temperature, and that termperature is favorable for life, then
it is merely a remarkable coincidence, for if things did not happen as such, humans would not be
around to question it. One of Gaia's most vocal critics in regard to this argument is biologist, W.
Ford Doolittle. In CoEvolutionary Quartery he writes,
| If the fitness of the terrestrial
enviroment is accidental, then is Lovelock not right in saying that for
life to have survived to reach the stage of self-awareness "is as unlikely as to survive unscathed a
drive blindfold through rush-hour traffic?" I think he is right ; the prolonged survival of life is an
event of extraordinary low probability. It is however an event which is a prerequisite for the
existence of Jim Lovelock and thus for the formation of the Gaia hypothesis... Surely if a large
enough number of blindfold drivers launched themselves into rush-hour traffic, one would survive,
and surely he, unaware of the existence of his less fortunate colleagues, would suggest that
something other than good luck was on his side. (Barlow, p.33) | |
Surely one must concede that just our very existence is not necessarily proof of some underlying,
non-chance mechanism causing the appearance of a homeostatic Earth.
Perhaps the most logical criticism of Gaia comes from how the theory is actually stated. This
criticism was raised by James Kirchner and John Harte at a 1988 conference on Gaia. They argued
that "the traditional, teleological, strong hypothesis is simply not testable, while the weaker forms, in
which life merely influences the enviroment, are so obviously correct that they do not merit status as
a hypothesis." (Kerr, p.393) For any hypothesis to be a good hypothesis, it must be stated such that
it is testable. Most of Gaia theory is not. While Lovelock has created his computer model of
Daisyworld to show his critics that a self-regulating planet can exist, it is only a computer model,
designed by its creator to show what he wanted. There is no way to predict how well an imaginary
model of 20 species relates to the real world of 10 million or more species. While an instructive way
to demonstrate how a homeostatic planet might operate, there is no basis to claim that any version of
Daisyworld can actually model the Earth.
Although their opponents are many, Lovelock and his fellow Gaia supporters are quick to defend
their point of view. Lovelock uses two points in his defense, the first from a scientific perspective
and the second from a more historical one. When originally proposed, Gaia has little supportive
data. It was difficult to find direct evidence of a global mechanism by which life affected the
atmosphere. However, recent years have possibly brought such evidence in the form of
dimethylsulfide or DMS, a compound formed by phytoplankton in the open sea. The regulation of
climatic concentrations of DMS may be the first example of life participating in feedback loops
involving the composition of the atmosphere. The basic feedback loop is as follows:
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1. A cooling climate favors species which are greater DMS producers.
2. A greater abundance of DMS in the water leads to a greater abundance of DMS in the
atmosphere.
3. DMS gas in the atmosphere act as nuclei around which water vapor can condense.
4. An increased number of nuclei leads to a higher concentration of cloud droplets.
5. More cloud droplets lead to more solar radiation reflected back into space.
6. An increase of solar radiation loss to space decreases the solar energy available to phytoplankton
for photosynthesis.
7. Less photosynthesis corresponds to lower phytoplankton productivity and lower DMS levels.
(Kerr, p.395)
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While like Daisyworld, this model is only speculative, it is unlike Daisyworld in that all but the last
step have been confirmed through observation. Whether or not a decrease in solar radiation would
lead to a decrease in phytoplankton production of DMS is still unknown. However, this does appear
to be promising of the first example of life regulating its environment on a Gaian scale, and if
proven, would be a huge boost to Gaia supporters.
Lovelock's second defense of Gaia temporarily pushes pure science aside, and examines the theory
in a greater historical context. He believes that some scientists, presumably the reductionists, are
taking Darwinism to too great an extreme, thus hindering the progress of biology at a time when
science has reached the limits of Darwinism. He writes, "Darwinism is still the great enlightenment
of biology ; yet, preversely, zealous disciples of Darwin by taking his words as if they were
revelations, not just the thoughts of a scientist, are making a creed for biology and so hindering it
natural development." (Lovelock, p.211) The scientific world has now realized that organisms do
not only adapt to their environment, but also coadapt with the environment, sometimes changing it
in the process. It is time for biologists to realize that although Darwin's insights are no less correct
now than they were a century ago, it's time to build on them, amend our theories, and continue in
our quest for an understanding of life that deals not with the absolutism of the individual, but rather
with the full relationship between the individual and its environment.
By this point, it shoud be clear that there is great disagreement between Dawkins and Lovelock as to
what are the underlying mechanisms of life. While at first it would seem if this disagreement were
based mainly on scientific perspectives, it is actually much more complex. It is also the result of
differences in their use of language and in their individual philosophies concerning the place of
science in society. The language difference is best exemplified by Lovelock's personification of
Gaia as if it were a conscious, sentient being. Obviouisly Lovelock does not actually believe that
Gaia is sentient, and after earlier criticisms, he goes out of his way to make this clear.
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Occasionally it has been difficult to avoid talking of Gaia as if she were known to be sentient. This
is meant no more seriously than is the appellation "she" when given to a ship by those who sail her,
as a recognition that even pieces of wood and metal may achieve a composite identity distinct from
the mere sum of its parts. (Lovelock, p.3) | |
Much of the resistance of mainstream science to Gaia has been due to Lovelock's reference to Gaia
as "she". Many scientists view this as almost the remnants of some kind of pagan worship of Mother
Earth, too abstract and quasi-religious to be taken seriously. Although Lovelock tries desparately to
avoid this view, it is difficult when he writes paragraphs such as the following:
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Gaia is no static picture. She is forever changing as life and the Earth evolve together, but in our
brief life span she keeps still long enough for us to begin to understand and see how fair she is. The
evolution of Homo sapiens, with his technological inventiveness and his increasingly subtle
communications network, has vastly increased Gaia's range of perception. She is now through us
awake and aware of herself. She has seen the reflection of her face through the eyes of astronauts
and the television cameras of orbiting spacecraft. Our sensations of wonder and pleasure, our
capacity for conscious thought and speculation, our restless curiousity and drive are hers to share.
(Barlow, p.19) | |
With excerpts such as this and its metaphorical language, is is easy to see how Dawkins and his
fellow reductionists are able to condemn Gaia theory as being far too teleological to be taken
seriously.
Although Lovelock's use of language plays a large role in the Gaia versus Selfish Gene debate, an
even larger role is played by the differing philosophies or the reductionists and the holists. The
reductionists view science as existing distinct and separate from other disciplines. They see no need
for science to become weighed down by its potentially deep philosophical and religious implications.
Early in The Selfish Gene's introduction, Dawkins makes a point of stating, "I am not advocating a
morality based on evolution. I am not saying how we humans morally ought to behave." (Dawkins,
p.2) Dawkins wants no part of a debate on human morals. He also apparently wants no part of a
debate on religion. Even earlier in the introduction he quotes zoologist, G.G.Simpson as saying,
"...all attempts to answer that question [What is man?] before 1859 [the birth of Darwinism] are
worthless and that we are better off if we ignore them completely." (Dawkins, p.1) Such a bold
statement will more than likely receive much opposition from those of a religious disposition.
Lovelock, on the other hand, happily discusses the religious consequences of Gaia theory, even
going as far as including a chapter in his book entitled, "God and Gaia". In this chapter, Lovelock
states, "Gaia is a religious as well as a scientific concept" (Lovelock, p.194) and he continues to
discuss how the science/religion dichotomous nature of society can be resolved. However, this
statement seems to contradict the unwritten rule against contempory scientists mixing their science
with religion. Most reductionists would take the position that religious implications of their work
should be left up to the world to resolve, and should not be their individual responsibility.
Responsibiliy also appears in another context within the Gaia versus Selfish Gene debate, and that is
whether one's scientific theories should advocate personal responsibility. We have already seen
Dawkins' opinion of this ("I am not saying how we humans morally ought to behave"), but what
does Lovelock say? He uses Gaia as a call to arms against the "ruthless" destruction of the
biosphere. He condemns deforestation and the increase of greenhouse gases. He describes one
possible future for our planet as such:
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At the present rate of clearance, it will not be long before the forests no longer have the critical mass
they need to exist as self-sustaining ecosystems. When they vanish, the billion poor of those regions
will be left with little to support them and in a harsher climate. This is a threat comparable in scale
to a global nuclear war. The human suffering, the refugees, and guilt, and the political
consequences of such an event have all been described... (Lovelock, p.266) | |
Refugees? Guilt? Political consequences? Dawkins has no time for any of these things. Whereas
Lovelock's descriptions of the interrelatedness of Gaia to other aspects of society helps to win him
support from the public, his dedication to showing the big picture only aids in his ostracism from
mainstream science by the reductionists. The reductionists, almost by definition, have little interest
in the big picture, as they see the big picture as simply too unscientific in nature.
So now where does that leave us, people who are both committed to scientific rationalism, but also
interested in the big picutre? How can we explain both the natural selection of our genes and the
self-regulating properties of our planet with a single theory? Are we any closer to a resolution of
this debate? I think that such a resolution is close indeed, as Gaia and the Selfish Gene approaches
to our existence are not nearly as mutually exclusive as either side would like us to believe. In the
early 20th century, an analogous debate arose within the field of physics concerning the nature of
light. Soime physicists believed that experiments such as the photoelectric effect and the Compton
effect could only be explained if one assumed light acted as a particle. Other physicists thought that
double-slit experiments clearly showed that light was a wave. For several decades, this
disagreement divided the field of physics and for some time it looked as if there was no resolution in
sight. That is, until Werner Heisenberg came along with his Uncertainty Principle and demonstrated
that light was both a particle and a wave - a difficult concept to understand, but one which showed
that neither of the earlier ideas was mutually exclusive of the other. Whether light acted as a particle
or a wave in any one particular circumstance merely depended on the construction of that specific
experiment.
I believe that the Gaia and Selfish Gene theories of life are very similar to the particle and wave
theories of pre-quantum mechanical physics. Whether life appears to regulate Earth's climate, or life
is only concerned with continued propagation of its own genes, merely depends on the specific
example one is examining at the moment. Biologist John Maynard Smith has said, "It would be as
foolish to argue about which of these views is correct as it would be to argue whether algebra or
geometry is the correct way to solve problems in science. It all depends on the problem you are
trying to solve." (Barlow, p.230) Perhaps James Lovelock and Richard Dawkins both have it right.
It is quite possible that the main source of their disagreement lies not with the scientific principles
behind their theories, but rather with the perspectives behind their views. Only after scientists
concede that their personal theories are not the only valid ways or viewing the world can the
scientific community hope to progress to a higher state of understanding.
