Tuesday, February 17, 2009

Organism Earth: The Gaia Theory...

The Gaia Hypothesis:

"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...A complex entity involving the Earth's biosphere, atmosphere, oceans, and soil; the totality constituting a feedback or cybernetic system which seeks an optimal physical and chemical environment for life on this planet."

"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?" -James Lovelock (1960s).

"Earth is a perfect planet for life but, according to Gaia theory, this is no coincidence. From the moment life first appeared on Earth it has worked hard to make Earth a more comfortable place to live. Gaia theory suggests that the Earth and its natural cycles can be thought of like a living organism. When one natural cycle starts to go out of kilter other cycles work to bring it back, continually optimising the conditions for life on Earth.

Named after the Greek Earth goddess, Gaia, the theory was developed in the 1960s by scientist Dr James Lovelock. At the time, Lovelock was working for NASA, looking at methods of detecting life on Mars. The theory came about as a way of explaining why the Earth's atmosphere contains high levels of nitrogen and oxygen.

Initially, Gaia theory was ignored, and then later ridiculed by scientists such as Richard Dawkins and Stephen J Gould. However, in recent times stronger evidence for the theory has emerged and Gaia has started to gain support. The theory helps to explain some of the more unusual features of planet Earth, such as why the atmosphere isn't mostly carbon dioxide, and why the oceans aren't more salty.

In its early years Earth's atmosphere was mostly carbon dioxide - the product of multiple volcanic burps. It wasn't until life arrived that the balance began to change. Bacteria produced nitrogen, an inert gas, and photosynthesising plants produced oxygen, a very reactive gas. Ever since that time, about 2,500m years ago, Earth's atmosphere has contained significant amounts of nitrogen and oxygen, supporting life on this planet. The nitrogen helps to keep things stable, preventing oxygen levels from climbing too high and fuelling runaway fires. Meanwhile, the oxygen supports complex life.

Gaia also helps to explain how the oceans are kept in balance. Rivers dissolve salt from rocks and carry it to the ocean, yet ocean salinity has remained at about 3.4% for a very long time. It appears that the salt is removed again when water is cycled through cracks on the ocean floor. This process keeps the oceans' salinity in balance and at a level that most lifeforms can tolerate.

These processes are not thought to be conscious ones, or to favour any one life form over another. Gaia theory simply maintains that Earth's natural cycles work together to keep the Earth healthy and support life on Earth.

Lovelock argues that humans have now pushed Gaia to her limit. In addition to filling the atmosphere with carbon dioxide, we have hacked our way through the "lungs" of the planet (the rainforests) and driven many species to extinction. He thinks we are heading for a very warm world, where only polar regions are comfortable for most life forms. Eventually, he suspects, Gaia will pull things back into check, but it may be too late for the human race.

Feedback Loops:

Feedback loops often appear to keep the planet in balance. One good example of this is the way in which atmospheric carbon dioxide is kept in check. Carbon dioxide is pumped into the atmosphere by volcanoes, and removed by the weathering of rocks (encouraged by bacteria and plant roots in the soil). When it reaches the sea, the dissolved carbon dioxide is used by tiny organisms, known as coccolithophores (algae), to make their shells. When coccolithophores die they release a gas - dimethyl sulphate - which encourages the formation of clouds in the atmosphere.

When atmospheric carbon dioxide levels become too high, coccolithophores get busy, locking up more carbon dioxide in their shells and pumping dimethyl sulphate into the atmosphere when they die - producing clouds which reflect back sunlight and help the Earth to cool. Conversely, if atmospheric carbon dioxide levels become low, coccolithophores reduce their activity. Over the past 200 years mankind has greatly increased atmospheric carbon dioxide levels, and recently there has been evidence that algal blooms in the ocean are increasing. Could Gaia be trying to correct our mistake?

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 the 20th Century."

-Kate Ravilious ("Perfect Harmony," Guardian UK, 4.28.2008. Image:-Hieronymus Bosch, Detail from the Triptych: "Garden of Earthly Delights", Museo del Prado, Madrid, 1500 ).

4 comments:

Qupid said...

Final Fantasy 7's world was known as Gaia, and the story played on much of the Gaia theory. I've rarely heard the theory mentioned seriously in reality, but I think it's interesting. The summarized theory seems to avoid issues such as volcanic eruptions, tornados and earthquakes, which would suggest that Gaia attempts to eradicate life at times rather than nourish it. It's almost like a "god of the gaps" argument, where the Earth becomes an intelligent being because we just can't fathom how else the planet could sustain life so well. Then someone makes a discovery, like the one about the cracks in the ocean floor maintaining the ocean salinity, and it's like... okay, so it just because there are cracks, or does it really have anything to do with intention?

Are the other planets just too selfish to welcome life, or are they, perhaps, "psychologically" dysfunctional? Are they dead?

I think if a planet could actually try to make itself inhabitable, its lifeforms would be dominantly planet eaters. The fact that so many creatures devour each other to survive makes it sound like survival is more of a desperate matter than one of being nourished by a greater being.

In any case, Gaia theory is a good discussion starter.

Lilika said...

I grew up with the belief that the Earth is our Mother and we are all connected. The Universe - everything... Alive and Connected. I personally think to anthropomorphise the Earth is just a way (mine) to understand that connection. Since we were born here - the Earth pretty much *is* our Mother. Native Americans believe that everything has Mana or energy/lifeforce even rocks. On the Subatomic level everything is energy. I also believe we are reflections of our Mother and her condition. Love the Bosch picture btw.

Jason said...

Most working scientists already accept that organic/inorganic distinction they make is an arbitrary one. Given that's the case, newly defining Earth as an organism makes little or no difference to improve our current understanding of biology. It's simply shuffling of language that we are doing here. Sure, it sounds more grandure and mystical to say that entire Earth is living, but what difference does it make?

ian said...

I disagree.

The Earth (Gaia), has not evolved in an environment competing for resources with other organisms of it's own kind.

Yet.

Once we (it), "reproduces", and the terraformed children - Mars and Venus start evolving on their own, we may be in contention for sunlight as our only source of energy after we have used up all of our own. Then it's just a race to see who gets to be the Dyson Sphere!