Section 2

Dr James Lovelock: Formulation of the Gaia Hypothesis
 

BACKGROUND: Primitive ExtraTerrestrial Glimpses ...

In the search for the evidence of extra-terrestrial life, the closer - Earth’s neighboring planets - Venus and Mars were targeted by the NASA program. Of these, due to the unknown conditions of the planetary surface caused by the dense and agitated Venusian atmosphere, the planet Mars was given priority. The first spacecraft to visit Mars was Mariner 4 in 1965, and several others followed including the two Viking landers in 1976.

Dr James Lovelock, a British Chemist specializing in the atmospheric sciences, was a recognized leader in his field. He was to invent an electron capture detector, capable of tracing extremely small amounts of tracer elements in gases, which was used by the ozone monitoring research concerning the effect of CFC’s in the early 1970’s. Almost a decade before this, NASA and the Jet Propulsion Laboratory (JPL) requested the presence of Lovelock in their project teams relating to the scientific search for the evidence of life on Mars.

In collaboration with other project researchers, Lovelock predicted the absence of life on mars based on the consideration of the Martian atmosphere and its state of being in a chemically dead equilibrium.

In contrast, the Terran atmosphere is in a chemical state described as being far from equilibrium. The unlikely balance of atmospheric gases which comprise the Earth’s atmosphere is quite unique in our solar system. This fact would be clearly visible to any extra-terrestrial observer, by comparison of the images of the planets Venus, Earth and Mars.

And so it was to be in the history of mankind, in the last handful of decades of the second millennium, mankind journeyed into space and became - through image technology - an extra-terrestrial observer:

VENUS	EARTH	MARS
CO2 (95%)	N (77%), O (21%)	CO2 (95%)

The question which Dr James Lovelock obviously asked himself was ...
WHY was the Earth different?

• Research concerning the chemical analysis of the composition of the Venusian atmosphere has yielded figures of 95-96% carbon dioxide, 3-4% nitrogen, with traces of oxygen, argon and methane.

• The same analysis for Mars returns 95.3% carbon dioxide, 2.7% nitrogen, 1.6% argon, only 0.15% oxygen and only 0.03% water.

• In comparison the Earth’s atmosphere at present is 77% nitrogen, 21% oxygen with traces of carbon dioxide, methane and argon.

What was happening upon the Earth which enabled the maintenance of such an unlikely combination of chemical gases - specifically nitrogen and oxygen. What complex processes are at work within the terrestrial atmosphere - and have occurred for many billions of years - to explain this uniqueness?

How have these processes arisen and what today maintains these processes at this equilibrium which is chemically far from equilibrium?

 

Why is it so?

In the late 1960’s Lovelock took the first steps in answering these questions by considering the the beginnings of life upon the planet Earth.

The earliest of life-forms existed in the ancient oceans and were the smallest and the simplest - less than single celled. Contemporary microbiological research points to the fact that almost 3 billion years ago, bacteria and photosynthetic algae began extracting the carbon dioxide from the atmosphere and releasing oxygen back into it.

Gradually - over vast geological time spans - the atmospheric chemical content was altered away from the dominance of carbon dioxide, towards the dominance of a mixture of nitrogen and oxygen - towards an atmosphere which would favorably support organic life powered by aerobic combustion - such as animals and mankind.
 

How the Gaia Hypothesis was so named...

So it was then that Dr James Lovelock, in looking for the evidence of extra-terrestrial life on Mars, observed the Earth as might an extra-terrestrial, and began to formulate a method of explanation as to why the Earth appeared therefore to be not so much a planet adorned with diverse life forms, but a planet which had been transfigured and transformed by a self-evolving and self-regulating living system. In view of the nature of this activity, Earth seemed to qualify as a living being its own right. And so the hypothesis took its initial form.

And as the story goes, while on a walk in the countryside about his home in Wilshire, England, Lovelock described his hypothesis to his neighbour William Golding (the novelist - eg: Lord of the Flies), and asked advise concerning a suitable name for it. The resultant term "Gaia" - after the Greek goddess who drew the living world forth from Chaos - was chosen.

Thus the Gaia Hypothesis was first postulated.

However, there was a big difference between postulating such a grand schemed hypothesis and having it accepted by the traditional scientific community, and there remained much research work to be done in order to be able to more clearly specify the entirety of the processes by which the modern planetary atmosphere had been evolved and was continuing to be evolved.

And in this task, in the early years of his further research concerning the Gaia hypothesis, Lovelock was supported by the collaboration of Dr Lynn Margulis, a leading and forward thinking American microbiologist.
 

Gaia: A New Look at Life on Earth - [1979]

By 1979 James Lovelock had published some of his ideas in a first book "Gaia: A New Look at Life on Earth" in which the statement of the specification of the Gaia Hypothesis had become somewhat better defined.

In this book we find him putting forward the postulate:

’...the physical and chemical condition of the surface of the Earth, of the atmosphere, and of the oceans has been and is actively made fit and comfortable by the presence of life itself. This is in contrast to the conventional wisdom which held that life adapted to the planetary conditions as it and they evolved their separate ways.’’

Elsewhere, in relation to the definition of Gaia we find the following:

"The entire range of living matter on Earth from whales to viruses and from oaks to algae could be regarded as constituting a single living entity capable of maintaining the Earth’s atmosphere to suit its overall needs and endowed with faculties and powers far beyond those of its constituent parts...[Gaia can be defined] as a complex entity involving the Earth’s biosphere, atmosphere, oceans, and soil; the totality constituting a feedback of cybernetic systems which seeks an optimal physical and chemical environment for life on this planet."

And in another section we find speculative thoughts concerning Gaia, and one’s which probably appealed to many of the readers who supported the various environmental groups, but at the same time provoked the hard-lined scientific critics of the Gaia Hypothesis:

"To what extent is our collective intelligence also a part of Gaia? Do we as a species constitute a Gaian nervous system and a brain which can consciously anticipate environmental changes?" [p147]

The Gaia Hypothesis has often been described by commentators as one of the most provoking singular ideas to have been put forward in the second half of this century, and while it struggled to be formally accepted in the fields of the traditional sciences in the 1970’s and early 1980’s, it certainly managed to provoke its share of debate.

During this period, Lovelock prepared for a second publication.

 

The Ages of Gaia: [1988]

A Biography of Our Living Earth
Almost a decade after having the first book prepared, and almost twenty years since initially considering the nature of the living systems which are clearly in evidence in operation within the terrestrial ecosystems, Lovelock had published a second book, entitled "The Ages of Gaia".

In this we find - naturally enough - that the presentation of his ideas are more mature, researched and informed. Moreover, the interconnectedness of the all the natural terrestrial systems - not just the atmosphere - was beginning to emerge in his consideration of those original questions.

We see Lovelock evolving and refining the specification of the nature of Gaia:

"The name of the living planet, Gaia, is not a synonym for the biosphere - that part of the Earth where living things are seen normally to exist. Still less is Gaia the same as the biota, which is simply the collection of all individual living organisms. The biota and the biosphere taken together form a part but not all of Gaia. Just as the shell is part of the snail, so the rocks, the air, and the oceans are part of Gaia.

 

Gaia, as we shall see, has continuity with the past back to the origins of life, and in the future as long as life persists. Gaia, as a total planetary being, has properties that are not necessarily discernable by just knowing individual species or populations of organisms living together ...

 

Specifically, the Gaia hypothesis says that the temperature, oxidation, state, acidity, and certain aspects of the rocks and waters are kept constant, and that this homeostasis is maintained by active feedback processes operated automatically and unconsciously by the biota."

Lovelock goes on to say ...

"You may find it hard to swallow the notion that anything as large and apparently inanimate as the Earth is alive. Surely, you may say, the Earth is almost wholly rock, and nearly all incandescent with heat. The difficulty can be lessened if you let the image of a giant redwood tree enter your mind. The tree undoubtedly is alive, yet 99% of it is dead.

 

The great tree is an ancient spire of dead wood, made of lignin and cellulose by the ancestors of the thin layer of living cells which constitute its bark.

 

How like the Earth, and more so when we realize that many of the atoms of the rocks far down into the magma were once part of the ancestral life of which we all have come."

While the scientific communities continued to debate the level of acceptability of the Gaia Hypothesis, the global and holistic perspective of the concept continued to capture the imagination of people from all walks of life.

The indigenous cultures who saw the nature of earth as a sacred spirit, others who sought the "oneness" in nature, those concerned for the environment - the trees, the rivers and the oceans, and those seeking contentious and revolutionary ideas, and those seeking religious frameworks - to an increasing multicultural and multidisciplined audience the concept of the Gaia Hypothesis was nourished and supported as a New Age paradigm.

Multicellular Red Herrings flourished in the primordial seas of Gaian debate during the 1970’s and 1980’s [and of course still do to a large extent] and while the non-scientific applicability of the concept flourished far and wide, they tended to very much to reduce the concentration upon the primary scientific issues of the hypothesis, its analyses and the implications of these.

Largely however, these misunderstandings were unavoidable in the initial statements of the specification of the hypothesis due to its intrinsic holistic nature and the scope of the global concept which it attempted to portray. Moreover, what was becoming clearer was that the concept had applicability to many disciplines and to many inter-disciplinary issues. The problem was in being specific.

Skeptics had argued (and still do) that this Gaia was teleological - that it supposed the evidence of some design or purpose in the nature of the biosphere - in particular the administration thereof - and that this was contra to the accepted position of Darwinian evolutionary doctrine which supported natural selection. Dr Lynn Margulis had much to reply in this area regarding the systematics of Darwinian evolution in regard to the smallest and earliest of living things upon the earth.

Yet in his research and in the above publication, Lovelock countered this argument with ecological considerations:

"Theoretical ecology is enlarged. By taking the species and their physical environment together as a single system, we can, for the first time, build ecological models that are mathematically stable and yet include large numbers of competing species. In these models increased diversity among the species leads to better regulation."

And then later, elsewhere in the Ages of Gaia ...

"When the activity of an organism favors the environment as well as the organism itself, then its spread will be assisted; eventually the organism and the environmental change associated with it will become global in extent. The reverse is also true, and any species that adversely affects the environment is doomed; but life goes on."

But perhaps the most popularly known counter-argument employed by Lovelock at this time (in fact in 1983) was the systematic behavior of the theoretical planet of Daisyworld which, like the earth, maintained its global temperature reasonably constant in the face of time and the increasing energy output of its sun.

 

Daisyworld

The following account of the Daisyworld is an extract from Guide to the Blue Planet by M. Bjornerud, J. Hughes and A. Baldwin, 1995.

I would therefore like to expressly thank Marcia Bjornerud and the Department of Environmental Studies at Lawrence University for its original preparation:

"James Lovelock’s Daisyworld is a hypothetical Earth-like planet, the same size as Earth and orbiting the same distance from a star similar to Earth’s Sun. Like our Sun, this star has grown progressively brighter through time, radiating more and more heat. Yet the surface temperature on Daisyworld has remained nearly constant for most of the planet’s history.

 

This is because the biosphere on Daisyworld, which consists only of dark-, light-, and gray-colored daisies, has acted to moderate the temperature. The daisies influence the surface temperature simply through their albedo or reflectivity. Dark daisies absorb most of the Sun’s heat; light-colored daisies reflect much of it back to space. Gray daisies absorb about as much heat as they reflect.

 

But how could the reflectivities of individual daisies affect the global temperature?"

 

[A] Early in the history of the planet, when the young Sun was still relatively cool (see figure below), dark daisies would be the fittest species, because clusters of them create local warm spots that favor the growth of more daisies. Soon the planet would be covered by dark daisies, and their collective effect would be to increase the global temperature above what it would have been in the absence of life

[B] When the dark daisies had established a comfortable temperature, gray and white daisies would begin to take advantage of the pleasant conditions. At first, gray daisies would do better than light ones because clusters of reflective light daisies wouldn’t be able to keep local temperatures warm enough for survival.

 

Global Temperature and Daisy Population
vs. Time & increasing Sun on Daisyworld

 

[C] Eventually, the Sun’s output would reach the point where unmoderated surface temperatures would exceed the maximum tolerable to daisies.

[D] At this point, light-colored daisies would begin to become the fittest species because clusters of them would create cool spots that would favor the growth of more daisies. As light-colored daisies spread, their collective effect would be to decrease the global temperature well below what it would have been in the absence of any life forms. In this way, individual daisies, without knowledge of or concern for the planet as a whole, would have acted to control the global environment.

[E] Finally, the heat produced by the Sun would be so great that neither type of daisy would be able to moderate the temperature, and all species would die out.

 

NOTE: In the lower plot, shaded area indicates temperature range tolerable by daisies.

Thus Lovelock attempted to answer the critics who perceived Gaia to be teleological.

Daisyworld as depicted above is a model that shows the manner in which a homeostatic state can be maintained by individual organisms acting only in their own interests - affording the global system a reasonably constant temperature range in the face of growing solar strength.

The traditional physical earth sciences of geology, oceanography, meteorology and geography had beforehand never seriously considered or analyzed the complex nature of the ecological systems abounding in their respective domains and cross-domain systems. However it is interesting to note that James Lovelock and Lynn Margulis acknowledge the geologist-physician James Hutton’s concept of a living Earth as a forerunner to the Gaia hypothesis.

In fact, James Hutton (1727–1797), often considered to be the father of modern geoscience, authored the concept of the rock cycle, which depicts the interrelationships between igneous, sedimentary, and metamorphic rocks.

The upper part of the earth (mantle, crust and surface) can be envisioned as a giant recycling machine; matter that makes up rocks is neither created nor destroyed, but is redistributed and transformed from one rock type to another. It was Hutton who suggested that the proper study of the Earth should be by "geophysiology".

Just as human physiology can be viewed as a system of interacting components (nervous, pulmonary, circulatory, endocrine systems, etc), so too can the Earth be understood as a system of four principal components (atmosphere, biosphere, geosphere, and hydrosphere). Thus we find this more holistic approach the Gaian specification being made by Lovelock’s use of this term "geophysiology" for the investigations of Earth, life and ecological science. As with human physiology, it emphasizes its biological base, the perspective of the whole system, and an interest in systemic health.

In the same year (1988) that this second book was published, the debates concerning the Gaia Hypothesis within the scientific community were still in full swing, and it was therefore decided to hold a symposium in relation to this matter, at which various scientists had the opportunity of presenting papers.

The collective information presented at this meeting was - three years later - to become the substance of the third book concerning the Gaia Hypothesis to which Dr James Lovelock had contributed.

 

Scientists on Gaia - The Symposium [1988]

And the publication Scientists on Gaia
Edited by Stephen Schneider and Penelope Boston, MIT Press 1991

Clearly, as was evidenced at this symposium and in the resultant publication, there existed a great range of scientific opinion on the Gaia Hypothesis - dependant upon which issue of the concept was being discussed. And this is not really surprising in consideration of the implications of the hypothesis.

Implication in short ... That the Earth could be considered a vast living system in its own right.

That such a meeting of eminent physical scientists would actually convene over the discussion of such a matter would have been inconceivable to the traditional physical scientist a mere quarter-century earlier. In fact, just over one century earlier (1882), James Clerk Maxwell, the founding father of the modern physical sciences - specifically Electromagnetic Theory - published a book entitled "Matter and Motion".

Although it was written in non-technical terms for the aspiring nineteenth century "NewAge scientist", owing to its easy presentation, clarity and methodical exposition of the contemporary body of scientific knowledge, it was to become one of the standard texts for all future physical scientists - students and professors alike.

The very first article of the introduction is as follows:

Article 1 - Nature of Physical Science
Physical Science is that department of knowledge which relates to the order of nature, or in other words, to the regular succession of events. The name of physical science, however, is often applied in a more or less restricted manner to those branches of science in which the phenomena considered are of the simplest and most abstract kind, excluding the consideration of the more complex phenomena, such as those observed in living beings.

And yet here in 1988, a group of geophysical scientists convene a meeting over the Gaia Hypothesis - the hypothesis which implies that the Earth may be considered as a vast living system.

This would have been inconceivable - only prior to the time of space-flight. As a direct consequence of space flight - and through the technology of computerized image communications - for the first time in his generic history, man was able to physically perceive his native global terrestrial home from an extra-terrestrial vantage point.

And if it was not the early pictures of the earth which captured the attention of the planetary inhabitants, then it was the time in the year of 1969 when the Eagle landed on the moon.

As a result of this symposium of 1988, while it was still clear that the Gaia Hypothesis was not accepted by many of the contemporary peers of Lovelock, it was equally clear that there was growing support from the non-scientific members of the global community.

While the scientific community’s consideration of the Gaia Hypothesis was being readied for entry into its second decade of debate, the holistic ontology which it represented was eagerly applied to an extremely wide spectrum of ecological and environmental sciences, social sciences, intellectual and philosophical movements and other not-specifically-intellectual reforms which collectively grouped themselves - as a spectrum of humanity through the prism of Gaia - as "New Age".

Certain claims concerning the Gaia Hypothesis could not be refuted - in particular the claim that the biota has a substantial influence over certain aspects of the abiotic world.

We thus find Lovelock confident enough with the Gaia Hypothesis to the extent that he puts it forward - not as a hypothesis - but as the Gaia Theory:

"Gaia theory is about the evolution of a tightly coupled system whose constituents are the biota and their material environment, which comprises the atmosphere, the oceans, and the surface rocks. Self-regulation of important properties, such as climate and chemical composition, is seen as a consequence of this evolutionary process.

 

Like living organisms and many closed-loop self-regulating systems, it would be expected to show emergent properties; that is, the whole will be more than the sum of its parts.

Quite clearly, for many scientists - feet firmly planted upon Earth - who were immediately unprepared to relinquish the traditional scientific methodology, there were many flaws in Lovelock’s arguments. However, it also became evident at this symposium (Scientists on Gaia) that the Gaia Hypothesis presented not just one but a range previously unrelated issues concerning the complex nature of the global ecology.

This important point was addressed by James Kirchner (UC Berkeley). His constructive criticism was that the Gaia Hypothesis may be better viewed as a collection of related hypotheses, which could be classified within a spectrum from weak Gaia (which related to the known evidence of biochemical cycles) to strong (as a form of global physiology). Hence the polarization of pro- vs. anti-Gaia scientists is unnecessary and unproductive.

His preparation of this analysis was well received by other critics as a suitable working definition of terms, has been since commonly quoted in internet FAQ’s relating to Gaia, and is set out below:

James W. Kirchner went on to publish further critique in his article "The Gaia hypothesis: can it be tested?" in Reviews of Geophysics 27:2, 223-235, 1989.

In fact there is much traditional resistance to Gaia simply because it is claimed that it is not a scientific hypothesis in the Popperian sense as it cannot be falsified. On the other hand there are those who would argue that the Popperian definition implies the methodology of reductionism, and that reductionism may not be able to fully define the quintessence of extremely complex and inter-connected systems.

In response to such criticism Lovelock writes:

"Fortunately for me I was brought up in that school of science that
believes in reading the books after rather than before an experiment."

In conclusion to this section relating to the debate and development of acceptance of issues relating to Gaia during this 1988 Symposium, presentation of papers and their later publication in a book entitled "Scientists on Gaia" by Stephen Schneider and Penelope Boston (MIT Press).

The following extract provides a summarization of the development of the Gaia Hypothesis as at the 1990’s and attempts to delineate the relationship between it and the traditional doctrinal stream which has been named Earth System Science:

"For more than a century students of the evolution of the living and nonliving parts of the Earth have known that life influences the physical and chemical characteristic of the planet. Nevertheless, the dominant paradigm in earth sciences has been that inexorable inorganic forces, such as changing energy output from the Sun, collisions of the Earth with extraterrestrial bodies, continental drift, or other orbital element variations have been the principal driving forces behind climate twenty years ago.

 

James Lovelock and Lynn Margulis coined the phrase the Gaia hypothesis to suggest not only that life has a greater influence on the evolution of the Earth than is typically assumed across most earth science disciplines but also that life serves as an active control system. In fact, they suggest that life on Earth provides a cybernetic, homeostatic feedback system, leading to stabilization of global temperature, chemical composition, and so forth.

When first introduced in the early 1970s the Gaia hypothesis attracted the most attention from theologians interested in the possibility that the Earth controlled its environment on purpose (i.e., teleological implications), from those looking for "oneness" in nature, and from those defending polluting industries, for whom the Gaia hypothesis provided a convenient excuse whereby some collective set of natural processes would largely offset any potential damages from human disturbance to earth systems.

 

Although none of these aspects was underlined in the scientific work of Lovelock and Margulis, these nonscientific side issues diverted attention in the scientific community away from a serious analysis of the Gaia hypotheses and its implications.

 

By the mid 1980s, Gaia advocates and detractors began a series of critiques and counter-critiques, often carried out through third parties such as television documentary producers One of us (Schneider) having been party to such a debate came to realize the absurdity of the situation in which an interesting and controversial idea like the Gaia hypothesis was being debated largely in nonscientific forums, if at all"

Earth System Science is not entirely equivalent to the Gaia Hypothesis, although both take an interdisciplinary approach to studying systems operations on a planetary-scale.

Earth System Science seeks to understand the mass and energy transfers among interacting components of the Earth System (biosphere, hydrophere, geosphere, atmosphere, and anthrosphere), which is not entirely synonymous to the the Gaia principle which purports that for practical purposes it may be useful to consider the earth as if it were a living organism.

Clearly however, the new insights of global environmental and ecological modelling afforded by the Gaia Hypothesis, now Theory, by Lovelock and Margulis were beginning to open up an entirely new range of research projects, experimental programs and inter-disciplinary areas which beforehand were inconceivable to the structure of the traditional physical sciences.

In the closing years of the 1980’s and through the 1990’s many such new research areas were to be formally chartered, and it is not within the scope of this document to specify them all.

However, it is perhaps interesting to see an example, and the following brief account, given by Richard H. Gammon at Harvard University, concerns the specification of "geophysiology":

The habitability of the planet depends directly on the radiative/photochemical properties of biologically produced trace gases, which together constitute less than a percent of the total atmospheric burden.

These trace gases are generally the volatile, often methylated products of microbial metabolic processes occurring in low-oxygen sites in both terrestrial and marine environments. The present atmospheric composition, and consequently the present climate, reflects a balance of the flux of these reduced volatile species (e.g., CH⁴, CH³SCH³, N²O, reactive hydrocarbons, methyl halides) from microbial sources vs. the subsequent dispersal, photochemical oxidation, and redeposition of degradation products as nutrients to the planetary surface and awaiting microbes.

VENUS	EARTH	MARS
CO2 (95%)	N (77%), O (21%)	CO2 (95%)

The elucidation of the relevant chemical species, reactions, and fluxes governing the natural recycling of the element essential for life is the primary goal of the interdisciplinary research field called "biogeochemistry."

 

The controversial hypothesis that the living earth can best be understood as a self-regulating biochemical system which controls, or at least strongly influences, the mean state of the planet has stimulated recent research in which might be called "geophysiology" or "biochemical climatology."

Such it was then, that at the closing years of the 1980’s, although the Gaia hypothesis was still being debated from various traditional scientific disciplinarian viewpoints, the concept itself had promulgated a renewed research into the global (extra-terrestrial) perspective of the living and the non-living terrestrial systems.

The seed of ideas and research which in the past, prior to space flight and the Gaia Hypothesis, had fallen through the cracks of the floor of the traditional scientific structures, were now being caught in the newly spun networking of emergent inter-disciplinary scientific fields, and were flourishing.

 

James Lovelock - and the Gaia Theory - the 1990’s

To conclude this section on the presentation of the Gaia Theory and its development, I would present two more recent quotations from the continuing work by Lovelock in the publication of his ideas.

The first is to be found in a book by the author Christian de Duve, entitled "Vital Dust: A Cosmic Imperative" - Models assembled from spare parts in review of which Lovelock comments:

"The distinguished cosmologist Fred Hoyle made a rare error when he rejected the possibility that life might have originated on the earth’s surface. He thought it impossible for a living cell to evolve from the mix of chemicals coating the surface of the new-formed planet. He held this view strongly and said: such an event is as unlikely as that of a Boeing 747 rising, ready to fly, from a tornado-swept junk yard."

Further in this review, and concerning the microbiological research results which had been so supportive (in the work of Dr Lynn Margulis) of the Gaia Hypothesis and Theory, Lovelock acknowledges the ground breaking work of that field of science. Clearly, the advent of means whereby the behaviour of extremely complex systems may be analyzed - via data processing machinery - has assisted scientific understanding in many fields, no less in the fields of the Life Sciences.

In 1989, James Lovelock prepared the Forward to a work by the writer Elisabet Sahtouris entitled Earthdance: Living Systems in Evolution.

Recently, the entirety of the work has been made available on the web, with the author’s invocation of To my planet and its people, and the following continuation of Lovelock’s thoughts have been extracted and are presented:

The Gaia hypothesis, now accorded the status of Gaia theory, is maturing with experience and the tests of time, not unlike the humans of this book.

 

It is spurring a great deal of scientific research into the geophysiology of our living planet. It is also spurring philosophic conceptions of what it means to our species to be part of a living planet. Some of these conceptions stay carefully within the accepted limits of science; others have a religious bent.

 

Most, especially environmentalist conceptions, advocate for humanity, being primarily concerned with human survival. A few, taking a clue from my partner Lynn Margulis and myself, advocate for the planet and the much maligned microbes with which the Gaian system originated and which continue to do its basic work.

 

In the intervening years, even in the short time since I wrote my own words about Gaia being an unconventional topic, less eccentric scientists than I have declared Gaia more conventional, meaning that Gaia theory is now recognized as a legitimate and fruitful basis for scientific investigation and is thus being brought into the scientific fold. In our first account of Gaia as a system neither Lynn Margulis nor I fully understood what it was we were describing. Our language tended to be anthropomorphic and, especially in my first book, Gaia, poetic.

 

Not surprisingly, some scientists misunderstood our intentions and accused us of saying that organisms acted from some in-built purpose to regulate the planet’s climate and chemical composition. The notion of purpose in natural systems is of course a scientific taboo, a sin of heresy.

 

That heresy is avoided in the clearer modern version, which is Gaia theory. This theory sees the evolution of the material environment and the evolution of organisms as tightly coupled into a single and indivisible process or domain.

 

Gaia, with its capacity for homeostasis, is an emergent property of this domain. There is no more need to invoke notions of purpose or foresight in the evolution of this domain than there is in the evolution of our own bodies within Gaia

As the title of a recent article in Science put it, "No Longer Willful, Gaia Becomes Respectable."

 

This means that Gaia scientists will be constrained by bureaucratic forces, by the pressures of tenure, and by the tribal divisions and rules of scientific disciplines. That, in turn, means we will need some antidote to the inevitable separations and constraints.

 

We will need independent synthesizers and visionaries who can make sense of the data produced by the scientific establishment and present it to us in ways that make our living planet real to us within the Gaian context and thus give meaning to our own lives and those of our children and grandchildren.