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a) Hypothesis developed by James Lovelock and Lynn Margulis stating that life on a planet will maintain suitable conditions for life; that “the biotic community plays the major role in biospheric homeostasis” – Odum, 1993.

b) Extension of the above hypothesis stating that the Earth is a living creature, a “super organism”.

Background:

Dr. James E. Lovelock was a British specialist in atmospheric gases employed by NASA in the early 1960s. His life’s work on the Gaia hypothesis stems from this time. The Mars Viking probes required life detection instruments, to determine whether any life existed on the planet. Lovelock was required to develop atmospheric tests for the presence of life.

Lovelock considered Earth’s atmosphere – asking what it was about our planet that, studied from space, would tell us that life existed here. He concluded that the nature of Earth’s atmosphere (especially the high levels of oxygen – a gas which chemistry suggests would normally not exist in such high concentration) was sufficient proof of life. The fact that our near neighbours Mars and Venus have such high levels of carbon dioxide in a low energy equilibrium was, for James Lovelock, sufficient proof that the planets were lifeless.

These findings were communicated to NASA, though the Viking probes were still considered necessary to investigate the Martian landscape. James Lovelock, however, moved his focus to investigating the postulation he had made about life on Earth.

In this he was assisted by prominent microbiologist Dr. Lynn Margulis (at the time the wife of Lovelock’s office mate – Carl Sagan).

The hypothesis was named by author William Golding – a near neighbour of Lovelock’s. The name of the ancient Greek goddess of the Earth seemed fitting for the theory, but makes a rather inflammatory statement about the Earth itself.

Observations:

The nature of the Earth’s atmosphere and temperature indicates that some form of regulation is occurring. The following observations illustrate this fact:

Methane and Hydrogen concentrations: If not continuously replaced through biotic activity, Methane and Hydrogen gas would be unknown in our atmosphere.

Carbon dioxide levels: also far higher than chemistry alone would allow.

Temperature: though the sun has steadily increased in strength (by around 30% in the last 3.5 billion years), the average temperature has only fluctuated by approximately 5% from the current average of 15 degrees Celsius. Studies suggest that a 30% reduction in solar strength would result in a drastic drop in average temperature.

Oceanic salinity levels: geological weathering releases salts into the oceans, however, salinity levels have remained the same for millions of years. Bacteria in salt flats may be removing the salt from the oceans..

Life on Earth:

The Earth’s primary atmosphere was most likely formed through the process of outgassing: gases rising from the hot core of the Earth. Considering the warm climate in Earth’s early years, despite the weaker sun, a higher level of carbon dioxide at that time seems likely.

With the first anaerobic life on earth, the atmosphere began to change. These microbes released oxygen into the air as a byproduct of their respiration. As oxygen built up in the atmosphere, the aerobes evolved, and much carbon dioxide was trapped in the oceans by limestone forming marine organisms.

This reduction in carbon dioxide – a greenhouse gas – gives a reason for Earth’s relatively stable temperature when compared with the changing strength of the Sun.

The hypothesis:

Lovelock published his first book in 1979, though he and Margulis had previously written papers on the Gaia hypothesis.

“...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.''
-James Lovelock: “Gaia: A New Look at Life on Earth” (1979)

“…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."
-James Lovelock: “The Ages of Gaia” (1988)

Daisyworld:

Lovelock and Margulis’ hypothesis attracted no little criticism. Lovelock appeared to suggest that the Earth was in itself a living entity, and the hypothesis was seen as hinting at some form of altruism in nature, as well as consciousness, as the environment was altered for the good of all.

Lovelock developed Daisyworld as a counter argument to the latter comments. The gaia hypothesis does not require altruism or forethought, but relies of the activity, completely unconscious as it is, of all life in order to alter the environment.

Daisyworld is a hypothetical Earth-like planet, where only black and white daisies grow. By their nature, black daisies absorb most of the Sun’s heat, whereas white daisies reflect it back into space.

In the early years of the planet, when the atmosphere was very cool and the sunlight not strong, small colonies of black daisies would flourish at the equator. The colonies would, by absorbing heat, form warmer spots where the plants could flourish.

As the black daisies started to keep the earth’s atmosphere at a suitable temperature, white daisies would start to take advantage of the favourable temperature.

Slowly, the sun’s heat would increase to the point where the black daisies at the equator would absorb such quantities of heat as to preclude their survival. The black populations would retreat to the poles.

As the sun continued to heat up, the white daisy populations would flourish, reflecting the sun’s heat out of the atmosphere, and helping to maintain a temperature suitable for daisy life.

The daisies do not act for the good of all, they are not altruistic or conscious, they simply exist, and by existing, alter their environment.

Other examples of the hypothesis:

Attractive though the daisyworld model is, it seems simpler to take examples of this kind of homeostasis from real life.

Consider the current concerns as to global warming and the build up of carbon dioxide in our atmosphere. A result of this may well be the increased well being of plant populations, resulting in more plant respiration, thus having more oxygen fed back into the atmosphere.

The outbreaks of cyanobacteria (commonly known as blue-green algae) in extremely hot and nutrient rich waters may have a similar effect. The toxic substance will, through photosynthesis, produce more oxygen while trapping carbon dioxide.

One of the seven characteristics of life is the ability of the organism to alter its environment. Earth exists in a balanced homeostasis – some species producing oxygen, some producing carbon dioxide. Plants fix nitrogen as ammonia in the soil, counteracting the acidity that would otherwise build up. Trees flourish in areas where there is ample rainfall, only to have us find, when we fell the area for wheat, that the rainfall was in part caused by the transpiration of those trees.

All kinds of feedback can be seen as supporting the Gaia hypothesis. Perhaps my favourite is the notion that in overpopulated areas, disease is far more likely to break out – reducing population strain.

The Gaia Groupies:

Ever since its conception, the Gaia hypothesis has been taken up by environmental and religious groups for its portrayal of the Earth as a living being. How literally Lovelock intended for his analogy of a living earth to be taken is hard to tell. He seems to present it quite literally, referring to “the Living Earth”. Margulis, on the other hand, has always seemed to rather distance herself from the more mystic side of the hypothesis, confining her studies to the nature of the Earth’s homeostasis.

Religious groups are known to call on the “spirit of Gaia” for guidance and healing. The hypothesis has been taken to extremes – making it easy for its detractors to criticize.

Lovelock and Margulis’ hypothesis has become widely accepted in the scientific community, overcoming the disadvantages of its original “wacko” stigma. The science behind the hypothesis seems accurate, and the question that remains is how far the analogy of a living Earth should be stretched.

Acknowledgements:
“Ecology and our Endangered Life Support Systems” – Eugene P. Odum, 1993.
http://www.physicalgeography.net/fundamentals/5d.html
http://www.mountainman.com.au/gaia_jim.html

Contrary to what James Lovelock and other miscellaneous hippies, crusties, and tree-huggers might tell you, if the Earth is a single interlocked self-aware lifeform - a Mother Earth, or a Gaia, to use a sickly phrase I have ever despised - She is probably not crying, screaming, or filled with anger and disappointment at Her wayward human sons. She is certainly not basically benevolent or healing.

Nope, she's probably cackling like a loony, bouncing off the walls, and contemplating how to chow down on the Great Red Spot of Jupiter with a nice Chianti and some fava beans.

Here's how I see it. Suppose that the Earth was a single, self-aware lifeform. What would it do all day? Spin round and orbit the Sun. Since it is incapable of movement, it can't dodge any asteroids or comets too well. In fact, the Earth is big enough that nothing could really hurt it (well, they could, but with some difficulty), and short of global thermonuclear war, it would be pretty tough to destroy all life on it. So all that remains is to play with its inhabitants just to prevent itself from going utterly insane.

Remember the omnipotent supercomputer AM in Harlan Ellison's "I Have No Mouth And I Must Scream" at all? Because it had nothing else to do, and saw itself as a slave, a pawn, whose very creation was an ultimate act of torment, it killed all but five of the entire human population and repeatedly tortured them for its own amusement? Well think about Gaia as being like that. Except worse, because of the planet's own evolutionary origins, survival of the fittest, and all that. It probably sees humanity as a rival that must be landed on with both feet. If Gaia doesn't get hers, nobody else bloody will! Hence, earthquakes, volcanoes, motorway crashes, Hurricane Katrina. These are indeed the will of Gaia, but they're not punishing humanity, they're TORTURING it. She's just playing with us because it's mighty alone in space, and there's nothing else to fucking do! And as far as she is concerned, what do a few poxy mammals have to do with the price of ice-cream? She's 4.6 billion years old and to her, we don't matter a hill o' beans. Imagine if you were trapped alone, with no way out, and you knew that there was no way out, and you knew that you were the only one of your kind, and you were functionally immortal. You'd be at the least pretty pissed off and, at worst, mad as a lorry. You'd be furious. And who or what can you take it out on? The ugly little apes that inhabit your surface. That's who. Nobody important's gonna miss them. And since you are somewhat limited in your physical faculties, and are thus unable to tear off their faces and boil them in vats of piss while masturbating to horse porn and la-la-la-ing the theme tune from "Leisure Suit Larry," you can but send natural disasters.

Or look at it like this. When I was a wee lad, back when girls were all icky and stank and had the dreaded lurgie, I used to have a board game called "Crossbows and Catapults." In this, each player built castles out of precariously arranged plastic blocks, towers, and put little model soldiers atop the battlements, then took it in turns to fire rubber-band-powered ballistae and trebuchets and mangonels at them. I used to love this. I'd build things up then see how epicly I could demolish them. The little model soldiers don't matter, they're little model soldiers. I just need to avoid breaking them beyond repair, and in any event, there's more where that came from. Then I'd build the whole lot up again, and repeat. I loved that game. Then when we got a PC (a Pentium 66, whoo!) and a copy of SimCity 2000, I'd build my cities up to have a few million folks in them, then use the "priscilla" cheat to send natural disasters one after the other after the other and see what they all did down there. And it didn't matter if I wiped my city off the map, I could just reload, et voilá! 914,782 virtual people all back. No big deal.

THAT's how we are to Gaia. "As flies to wanton boys" etc. Are we insignificant gnats to her? Does the Pope cover up for nonces? Exactly.

So think about that the next time some no-account Islingtonite greenie tells you that Eyjafjallajokull was the wrath of Gaia. The ash cloud wasn't Mother Earth punishing everyone who works at Heathrow for polluting the atmosphere, it was Her way of torturing us because She is a psycho.

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