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May 24, 2013

The Gaia Hypothesis

If you left Earth on a long spaceflight out into the universe because it was too lonely a thought to think that Earth was the only harbor of life in the universe, how would you search for it?  How would you recognize it?  What tools and perspectives would you take with you to help you find it?  Would you expect to find plants and animals just like here somewhere else?  Would you take a microscope and look for microbes because they are the hardiest and most survivable organisms known to us?  Would you only search for Earth-like planets with water and mild climates?  Would you look for massive societies that have changed the whole landscape of their planets?  Would you expect to pass someone wandering through space looking for life just like you?  Could you recognize it if you saw it at all?  Do we even recognize all the lifeforms that exist on Earth or are there still lifeforms that are commonplace, but unsuspecting--like a rock perhaps--because we lack the definition, perspective or technology to identify it?  Are viruses alive?  Modern science doesn't think so (still hotly debated) even though viruses reproduce.......in a way, metabolize..........in a way, and have bodies.........in a way.

You might realize by now that there's a glitch and that is that life is difficult to define.  Most definitions of life have an obvious bias, and that is that humans define as life what is most human-like and the further away the resemblance becomes the more leery people become to bestow the title of "life."  James Lovelock, an independent scientist and subject of this blog, pointed out something interesting by noting how we all must have some kind of instinctual life-finding mechanism.  It helps us survive if we know that something is alive and what kind of life it is.  Is it edible, dangerous, diseased, friendly, sexy, useful, etc.?  But our life-finding instinctual program isn’t infallible, up to the late 1800’s people thought yeast was a mere chemical catalyst that fermented sugar to alcohol.  We now know that yeast is a living organism that eats sugar and excretes alcohol as a waste product. 

James Lovelock was working for NASA in the 1960’s and 1970’s when he got the project to design a method of life detection for the space probes that were to be sent to Mars and elsewhere in the solar system.  He was an atmospheric scientist by training, but he had a vast interest in and knowledge of many subjects which he called upon to come up with a simple, but rather revolutionary idea.  His neighbor proposed the name Gaia, after the Greek God for Mother Earth, for the idea and it has appropriately become known as ‘The Gaia Hypothesis’ ever since.

The Gaia Hypothesis in aphorism form might go like, ‘if you want to find life, look for paradoxes.’  If you see a volatile atmosphere that maintains an equilibrium of volatile compounds without reacting to an inert state….life must be there maintaining the tense equilibrium.
An example…….

If we agree for the sake of making a point that a ladder is a non-living object and that a human being is alive we can try an experiment that involves a tightrope between skyscrapers!  If James Lovelock were to prove to you (albeit in a grossly over-simplified way) with The Gaia Hypothesis that a human is alive and that the ladder is non-living, he might try to balance the ladder with its two feet on a tightrope and point out that even when it is balanced and stays standing the slightest disturbance will topple it.  It can’t adjust itself to the improbable circumstance of staying balanced on a tightrope for long.  Whereas, not only can a human being be balanced and stay balanced on a tightrope between skyscrapers, but a human can also adjust to wind, sun and rain (and fear!) while purposefully walking the distance to safety.

The point to James Lovelock is that both a ladder, tall and skinny on two feet, and a human, tall and skinny with two peg legs, have a similarly, unstable shape and one would predict that neither would stay balanced for long on the wire.  Yet the ladder topples as one would predict whereas the human (albeit a highly skilled human), against predictions, stays standing and moves about with a self-regulating sense of balance.  Life, to James Lovelock, maintains by self-regulation a kind of intensity, an improbable equilibrium, against the forces of entropy that want to take all high-energy systems to their lowest and most stable state (planted in the pavement below).

Of course, James Lovelock, didn’t propose a tightrope walking proof to the scientific community when presenting his theory.  Rather he relied upon his scientific expertise and showed the insight he’d had while considering the atmospheric chemistry of Earth itself.  Before the Gaia Hypothesis meteorologists, geologists and chemists had explained the constant levels of the different atmospheric gases as the result of inorganic processes.  For example, the 21% oxygen content of the atmosphere was accounted for by the breakdown of oceanic water by sunlight into hydrogen gas (which mostly escapes into space) and oxygen gas.  When Lovelock examined this process closer he realized that for the amount of methane produced by living organisms (which readily reacts with oxygen in sunlight producing water and carbon dioxide) there was no way that the current levels of atmospheric oxygen could remain as high as they are; there had to be another source or process that was keeping atmospheric oxygen as high as it is.  Similarly, he looked at many of the gases that compose the atmosphere at constant levels and realized that the atmosphere is too volatile a place for inorganic processes to be regulating it.  If it were controlled by inorganic processes alone he believed that the atmosphere should be nearly 98% carbon dioxide and all other gases should only occur in trace amounts; but in fact, carbon dioxide is only at a current level of .03%.  It was facts like these that led James Lovelock to propose that life itself was regulating the composition of the atmosphere and that in fact the Earth itself could be seen as a kind of living entity where all organisms are collectively contributing to the stabilization of the environment.

Lovelock points out that despite variations in the climate of Earth over time (including hot periods and ice ages) that the environment has always been hospitable for life, as proven by the unbroken, 4 billion year long fossil record.  And not only has it been hospitable, but it has also allowed for an unbroken trend towards ever more organized levels of complex lifeforms.  He continues that it is safe to predict from scientific knowledge that the sun’s output, combined with geologic factors from Earth's past, has varied greatly enough in that time period that the oceans of the Earth should have completely frozen in some geologic eras and boiled mostly away during others, but the fossil record proves that this has never happened and that life has inhabited the oceans the whole 4 billion years.  This, he argues, is further proof of Gaia (that, collectively, life is regulating the climate on Earth to be hospitable for life).

A clarifying example would be the way we regulate our body temperature.  If we were dead we’d expect that our body temperature would passively match the environment’s temperature, but if we’re living, self-regulating and Gaia-like then we’d expect that our body temperature would stay steady no matter if the environment’s temperature were 40 degrees Fahrenheit or 110 degrees Fahrenheit.  Our body heat is very Gaia-like because it maintains the improbable equilibrium (considering how small we are compared to the forces of the surrounding environment) of 98.6 degrees Fahrenheit.  It is just these improbable equilibriums that one should be looking for when searching for life in the universe, according to Lovelock.

Gaia is about a collective, yet unconscious mutual effort to survive in which all organisms from whales to viruses, redwoods to spiders, lizards to humans, participate in regulating the planet’s atmosphere, oceans and land by offsetting each other’s negative impacts to keep Earth habitable.  By James Lovelock’s estimation all living things change their environment to meet their needs and all things “pollute” as a result of their activities.  Evolution is a process by which Gaia is maintained and the environment, rather than being overwhelmed by the pollution of certain organism’s activities (like humans for example), remains habitable as organisms evolve to offset the effects of others.  It’s all about cycles, balance and symbiosis.

Lovelock makes a philosophical argument to meld The Gaia Hypothesis into a coherent theory by explaining how organisms come to participate in the life-regulated Earth.  He asks if it’s unreasonable to suppose that by some instinct/disposition we might derive pleasure from seeing a beautiful, healthy environment.  If we do have such an "aesthetic sense" for our environment then it follows that we may be instinctually programmed to recognize our optimal role in relation to the life around us and thus derive pleasure from pursuing that harmony.

Perhaps James Lovelock paints too rosy a picture of life and the relationships it has amongst its members and the environment though, in truth, he has quite cynical opinions about the prospects for humanity.  The Gaia Hypothesis has been heavily criticized by orthodox scientists, but the volume of criticism has toned down since he proposed a mathematical model about how Gaia might work called Daisyworld.  Only time and further scientific evidence will determine what parts of The Gaia Hypothesis are correct and what parts are mere wishful thinking.  Regardless of outcomes, it is an influential idea of our time and an interesting one at that. 

Watch a Video
A recent measurement of the annual fluctuations of carbon dioxide gas in the atmosphere has been measured by a NASA satellite orbiting the Earth.  It actually affirms The Gaia Hypothesis because it shows that carbon dioxide, a greenhouse gas, naturally builds up in the atmosphere during the winter, helping keep Earth warm enough for life to survive, and gets removed from the atmosphere in the process of photosynthesis throughout the spring and summer to keep the Earth cool enough for life.  (By contrast, our orbiting moon, without an atmosphere at all has temperature fluctuations from 225 degrees Fahrenheit during daytime to -243 degrees Fahrenheit by night!)  Click the below link to see Earth "breathe".  The global fluctuations of carbon dioxide are shown about half way through the video. 

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