In the 1960's, James Lovelock, a British atmospheric chemist, was engaged in research commissioned by the National Aeronautic and Space Administration
NASA) in the United States. Specifically, the studies were intended to develop a method for determining reliably whether or not biological life existed on Mars. Part of Lovelock's work involved analyzing certain elements of Earth's atmospheric properties and mechanisms, in order to understand how a planet teeming with biological life might be differentiated accurately from interplanetary distances from a planet completely devoid of biological life (Enteractive, 1995).
While Lovelock's NASA research project originally pertained to Mars rather than to the Earth, his findings led him to postulate a theory in which he characterized
Earth as a complex living organism, rather than merely an inanimate host for the many terrestrial life forms dependent on it for sustenance. Lovelock called his theory
Gaia" after an ancient Greek Goddess of the Earth and published his ideas outlining the principle elements of Gaia Science in 1968. In his book GAIA: The Practical
Science of Planetary Medicine, Lovelock suggests that the Earth is itself a tremendously large and complex super-organism, comprising all of the (other) life forms dependant upon it in very much the same fashion that the human body comprises the many trillions of individual living cellular organisms that, collectively, constitute a human being (Lovelock, 1991).
Initially, mainstream scientists rejected the notion of a living Earth outright, and others objected to the characterization of Gaia as a scientific theory, suggesting that it represents merely a metaphor for what Earth scientists already know about the delicate balance of terrestrial life, rather than a new scientific postulate capable of empirical proof or disproof (Gould, 1991). More recently, Lovelock has found support for his ideas from other scientists such as Peter Liss, an environmental researcher, and renowned Harvard University sociobiologist, Edmond O. Wilson, author of the 1998 best seller Consilience: The Unity of Knowledge. Together,
Lovelock, Liss and Wilson launched a new venture in 1998 dedicated to promoting
Gaia science and research on Earth as a self-regulating system (AAAS, 1998).
Essential Elements of Gaia Theory:
Initially, what struck Lovelock about the chemistry of Earth's atmosphere was the preponderance of some of its individual gaseous elements without any apparent explanation for their failure to have combined into other substances, given the timescale involved. According to Lovelock, nitrogen in particular readily combines with oxygen, and his calculations suggested that the atmosphere contains billions of times more solitary nitrogen than it should. His conclusion was that the perpetual existence of so much elemental nitrogen in the atmosphere could not be explained by natural chemical mechanisms, but only by the effects of metabolic processes of living organisms and their interaction with the atmosphere.
Similarly, Lovelock suggests that the stability and relative uniformity of the gaseous composition and temperature of Earth's atmosphere could not be explained by ordinary inorganic chemistry. Furthermore, global climate has remained essentially the same despite the fact that the amount of solar energy that reaches the Earth varied significantly during that time, increasing quite substantially since the first appearance of terrestrial life. Lovelock (1991) proposed that a feedback loop or similar mechanism is responsible, whereby the organic processes of living organisms release so-called "greenhouse" gases to warm the planet when necessary, and that a stable temperature is maintained by their many deaths when the planet becomes too warm for them to survive.
According to Gaia scientists, complex mechanisms would also have had to replenish the atmospheric ammonia, carbon dioxide and methane in order to maintain such a stable global temperature via the greenhouse effect. Conversely, any global temperature increases beyond the normal range (whether from increasing solar radiation or organic overpopulation) would quickly result in the deaths of a proportionate amount of organic life to reduce the greenhouse effect in order to maintain the Earth's stable climate over time. Gaia theorists regard this as precisely the same type of biofeedback loops that enable (other) living organisms to maintain homeostatic equilibrium (Lovelock, 1991).
Lovelock (1991) proposes a very similar feedback loop-type of relationship between nitrous oxide produced by anaerobic microbial organisms living in the soil of the seabed to account for the stability of the correct proportion of oxygen to support biological life on Earth.
As far as the oceans are concerned, Lovelock (1991) explains the delicate maintenance of the optimal salinity for biological life through a complicated interrelationship between the terrestrial sources of salt that increase ocean salinity and the relative numbers of creatures with calcium carbonate-based shells. Likewise, he suggests that excessive salinity increases the death rates of minute oceanic creatures whose shells and skeletons become buried in the sea soil, thereby reducing ocean salinity when necessary.
In many respects, Gaia theory is neither such a radical concept, nor very different, necessarily, from the more traditional scientific descriptions of the Earth and its interrelationship with biological life. So many ancient cultures recognized the relationships" between terrestrial processes and biological forms of life, precisely because the myriad ways that living creatures are dependent on and interact with elements of the Earth and its atmosphere seem so obvious. In the absence of any scientific understanding about what life is, the planet may indeed seem too be "alive."
To be sure, this presumption of a consciousness expressing itself, through weather phenomena, for example, engendered the first beliefs in a supernatural
God." While our modern scientific understanding removes the supernatural association, the sheer complexity and complete ubiquity of terrestrial processes' supporting biological life is utterly breathtaking. Likewise, our modern medical understanding of biological processes and the microscopic organisms such as the beneficial bacteria that inhabit our digestive tract and assist in our digestion do seem to parallel the way Gaia theorists characterize the Earth.
On the other hand, the Earth does not qualify, automatically, as a living entity, simply by virtue of the fact that it takes part in physical processes involving living organisms. The existence of unequivocally inanimate interactive feedback loops that maintain stable conditions is not that rare in the universe, between and among entities that are clearly not alive in any sense of the word.
All the stars of our universe maintain a very delicate balance between the competing forces of gravity and outward pressure for billions of years. Those in the same class as our Sun maintain thermal equilibrium for ten or fifteen billion years.
During that time, their energy output is precisely controlled by the nuclear physics underlying the fusion of hydrogen into helium. More massive stars always burn out or "die" before less massive stars, and the even the galaxies organize themselves into fascinating spirals that seem to have "lives" of their own. Within many of those galaxies, massive black holes continually consume or "eat" matter that strays too close (Smolin, 1997). That does not suggest to anybody that stars and galaxies are living entities.
From an evolutionary perspective, it is difficult to consider the Earth to be capable of "evolving" in any manner similar to living creatures, precisely because Darwinian evolution is based, fundamentally, on the concept of competition between and among species. In evolutionary terms, "success" simply means increased likelihood of surviving to procreate and "failure" means decreased likelihood of surviving to procreate. Multiple species can certainly be said to evolve together, such as in predator-prey and parasite-host relationships, because their respective evolutionary success or failure may be interdependent (Gould, 1991).
One of the most fascinating aspects of biological evolution is that it takes place without any knowledge or purposeful participation of the organism, which would seem to allow the Earth to "co-evolve" along with (other) terrestrial living things in the exact same manner as do multiple species, at times. The problem is, whether they have any awareness of it or not, when living biological species automatically evolve (or co-evolve), whatever spontaneous adaptations and mutations are in their mutual "interest" (Gould, 1991).
This is an aspect of Gaia theory that seems to fail, because none of Earth's living organisms has any evolutionary incentive to benefit the Earth beyond its own brief existence; more significantly, the Earth does not reproduce and is not in Darwinian competition with any other planets or species. Therefore, while the earth changes and evolves over time, it would seem more characteristic of the way inanimate stars and galaxies change and evolve, rather than the way sentient living creatures do.
Critics point out that Gaia theories could apply to the entire universe as well as to the Earth and her many biological residents. All known life forms are carbon-based and all of elements that combine in the countless ways necessary for life to evolve were synthesized in the nuclear furnaces of long-dead stars. In that sense, Gaia concepts could include all of the trillions of stars and planets represented in the hundreds of billion known galaxies.
Fundamentally, it is inconceivable (to this writer, anyway) that the spherical lump formed from congealed interstellar dust and rock that we call "Earth" is a living…