Once again, if you missed the first three in this series they will be linked at the end. I am reviewing Dorion Sagan's book Notes from the Holocene {A brief History of the Future} with a lot of material thrown in from my own probing into these same issues. One of the influences behind my world view is the late Robert Rosen whose bibliography is listed on the VCU Complexity Research Group's Website. I encourage you to take a minute to click on the "bibliography" link because you will get a jolt from doing so. Most of you will never have heard of Rosen yet here is this vast amount of very exciting work about biology, life, etc. that began over a half century ago. It seems clear from Sagan's writing that he also was not aware of Rosen's work and that is a shame for he would have benefitted from it greatly. The best we can have is to look at them side by side and make our own synthesis. That is what we will do beneath the break
The topic I wish to examine in this diary is Sagan's idea that the earth System is like an organism that has a very highly regulated "homeostatic" system. From Wikipidea
Homeostasis (from Greek: ὅμος, homos, "equal"; and ιστημι, histemi, "to stand" lit. "to stand equally"; coined by Walter Bradford Cannon) is the property of either an open system or a closed system, especially a living organism, that regulates its internal environment so as to maintain a stable, constant condition. Multiple dynamic equilibrium adjustments and regulation mechanisms make homeostasis possible. The concept was created by Claude Bernard, often considered as the father of physiology, and published in 1865.
I have already established that the Earth system can be shown to fit Rosen's definition of "organism" as a result of some work I did some time ago. Rosen's definition of organism is the result of his grappling with Schroedinger's ill posed question "What is life?". I reviewed this in a paper I gave at the 1999 annual meeting of the International Society for the Systems Sciences when I was asked to fill in for Rosen after his death. You can read that review here. In summary, Rosen developed a mathematical model using Category Theory which he had begun to work on before I arrived at the University of Chicago in the early 1960s. He was in Rashevsky's Mathematical Biology Program and I was doing my doctorate in physiology. It took many years before I exhausted every approach I could learn, including the development of large computer models of physiological systems, and looked at Rosen's work as more than an interesting and deep study of a particular model. It was clear to me that Rosen had previewed the Complexity Science that would come to be a part of major universities all over the world. It was also clear that complexity science was the way to tackle the really hard problems of modern science.
Homeostasis is the the central theme of physiology. Ironically, the reduction of homeostasis to a bunch of "feedback" mechanisms was the best science could do to deal with this phenomenon of such great importance. Intrinsically, homeostatic regulation is an example of the closed loops of causality that define the organism as something apart from feedback regulated machines. Complexity science has allowed us to progess beyond that misrepresentation by acknowledging that these impredicative closed loops are not only a valid part of science but the core issue in most of complex reality.
So Sagan has presented us with a part of the picture, but his ideas gain a lot of strength when coupled with the still to be fully recognized work of Robert Rosen and his students. The homeostaticly regulated organism metaphor is the best way I know of beginning to grasp the very complex system that is our planet.
Let us examine some of the examples Sagan presents keeping in mind that as we speak about them piecemeal, they have interactions with each other and other important processes in the system, usually through the biosphere.
One clear player in the temerature regulation of the planet is the rainforest and other masses of vegitation. I have discussed this elsewhere in Who cares about rain forests? and Sagan discusses it in more detail in his book with Eric Schneider Into the Cool. There are a myriad of examples of the homeostatic levels of various substances in the oceans being in need of regulation to remain at their life and temperature sustaining levels. Among them:
Ocean salt levels:
Life's effect upon the Earth's crust is so pervasive that even the great tectonic movements beneathh the oceans may be connected to, if not prompted by , organismic collectives. Though not yet proven, a series of possible links suggests that the most apparently Herculean geological processes may be under biological dominion...To glimpse how life might be implicated in plate tectonics, consider first that the amount of salt we might expect to find in the ocean-ten times the existing levels-isn't there: Chemical and physical calculations show that salt from rivers and streams should pile up cumulatively in the great marine basins. Since there is no geological means to remove this salt, we have to assume tthat life itself keeps oceans free from the high levels of salt that would otherwise accumulate there. Marine creatures can not tollerate high salt concentrations, they are poisoned, not tickled but pickled to death, by such levels. So somehow the salt is removed... The missing salt appears to lie at the edges of the sea, dried up in costal deposits called evaporites... We now know that what Darwin saw were packed communities of bacteria. The exudates, or cellular secretions, of these beings wrap around particles of salt, preventing them from being dissolved again into the water. Such natural salt mining might work to hold vast quantities back from the ocean, but only if the land is broad and flat and in the tropics or subtropics so that sufficient evaporation can take place. With limestone acting as a lubricant, landmasses slide over the mantle, slipping especially over stationary sources of tremendous heat coming from within the Earth. The mobile plates tend to accumulate in the tropical and semi tropical zones where the slippery limestone is produced. Slipping about, they may create platforms for salt removal in their wake. While details of sifting salt from the oceans remain unclear, ocean salinity is probably being regulated.
Another example is ocean acidity as was pointed out by leming22 in the comments after the previous diary: peak fish
In the last diary we discussed the human side of the issue. We humans are a special case among living things. Can we ever really be an integral partr of the system without being a problem? Here's what Sagan says:
To explore how we might "become integrated in the biosphere system" and perpetuate our survival, consider the evolution of birds. Precisely their waste may have ensured them longevity. coming from reptilian progenetors, birds could have precipitated an improvement in the recycling of an element vital to the biosphere functionin: phosphorous, found in DNA. Birds may have bichemically "pushed" the biosphere, increasing global metabolism, the efficiency of the distribution of nutrients in a globally recycling system. It appears that birds not only did what it took for them to survive on their own, but were perpetuated because they found a niche within the planetary nexus, enhancing the connected activities of other porganisms. They were "selected" not only by competition in various environments but also by Gaia, the global environment as a thermodynamic whole.
For a long time there has been what ammounts to a "phosphorous crisis" in the biosphere....The chronic shortage of phosphorous imposes an absolute limit on the abundance of life in shallow waters....Birds may have alleviated this bioshere shortage by doing something often advocated in the human realm: They improved not the quantity of food but the means of distribution....Bird droppings- a major component of which is biologically assinilable phosphorous-long ago spread phosphorous on a global scale.
Then there are the termites. Yes, those miserable creatures that eat our houses are also knights in shining armour in the Earth system.
The equivalent of one-third of the matter grown by plants each year is devoured by wood-eating termites and moves through their insides ; much of this matter becomes the atmospheric gas methane. Methane is a more powerful greenhouse gas than carbon dioxide. It reacts with oxygen to make carbon dioxide and water. Does it-like trace chemicals in our own body-have a natural function?
Termites occur over about two-thirds of the earth's land surface; there may be as many as three-quarters of a ton of termites for every person in the world. Moreover, termites convert roughly 1 percent of the carbon in wood into methane, in the process producing as much as half the methane in the atmosphere. Since methane may be necessary to stabilize the atmospheric level of oxygen, and since termites produce so much "natural gas" they may be playing a crucial role in the atmosphere, the biosphere's circulatory system.
Rather than make this longer I will refer you to Sagan's book for more details and examples. I want to close by pointing out these examples of regulation almost always involve an interplay between life forms, physical processes, and the chemical composition of large parts of the system. Anyone who thinks we can do a better job of controlling this myriad of variables and processes had better think twice. We are only beginning to understand.
Here are links to the first three diaries in this series:
My first Eco-diary: The earth is Alive?
Eco-diary series #2: Earth, Water, Air, and Fire
Eco-diary #3: The human side of the issue