Gaia hypothesis
The Gaia hypothesis was developed by the microbiologist Lynn Margulis and the chemist, biophysicist and physician James Lovelock mid -1960s. It says that the Earth and its biosphere can be considered as a living being, so far as the biosphere ( the totality of all organisms) creates and maintains conditions that allow not only life, but also an evolution of more complex organisms. The Earth's surface is thus a dynamic system, which stabilizes the entire biosphere by human influences responsive mechanisms. This hypothesis assumes a specific definition of life, according to which living beings are characterized in particular by the ability to self-organization. The name is derived from Gaia, the earth goddess and the Great Mother of Greek mythology, from. The Gaia hypothesis in turn motivated employment fields such as Geophysiology, landscape ecology provides in a holistic context.
Empirical foundations for the Gaia hypothesis
In her books, the founder of the Gaia hypothesis wear together various facts used to justify the image of self-organizing, "living" planet. Younger geoscientific findings have further fueled the discussion.
As oxygen
Molecular oxygen is a highly reactive substance that compounds with other elements received in a short time and then disappears. Iron rusts, wood burns. The amazing thing is now, however, that the oxygen content of the atmosphere is constant: No matter how much iron rusts and how much wood burns, the global oxygen content remains unchanged. 'll Especially exciting this when one considers that " fossil air " from ice cores or amber a very similar, often has the same composition as the present. Obviously, the oxygen content of the air has, since the life in the country is active, changed only slightly. The Gaia hypothesis is that the system itself keeps " life " stable the unit. ( One consequence of this consideration is that another planet with an atmosphere containing oxygen and a gas that reacts with oxygen, must harbor life -. Yet no one is discovered, the atmosphere of Jupiter 's moon Europa contains oxygen, but not appreciably different substances. )
Example, climate variability
Increasingly, evidence is accumulating that up to 600 million years ago the climate was exposed to extreme fluctuations, which no longer existed ever since. At times, the earth was therefore of a layer of ice literally covered ( " Snowball Earth " ) while she was completely free of ice at other times. Critics of the Gaia hypothesis argue, therefore, that such extreme variations in the idea of a balance held in the Earth contradict each other.
Proponents see it the other way around: An explanation for these early climate variability is that there were no complex organisms with calcareous shells or skeletons in that early time ( Precambrian). Because today the calcareous marine plankton plays an enormous role in the CO2 budget of the oceans. When these organisms grow, they take carbon dioxide ( CO2) from the water, and when they die again, they fall together with its calcareous shell on the seabed, where then form massive carbonate sediments over millions of years. In this way, chemically stabilized, the CO2 content of the oceans - thus indirectly of the atmosphere. The emergence of these organisms would therefore have helped to stabilize the conditions of life on earth and thus to improve.
Example salinity of the oceans
The salinity of the oceans is constant at 3.5%. Although considerable amounts continue to be resolved in minerals and transported into the sea from the land, the salt content for millions of years has not risen. Assuming that the mineral cargo in earlier times was similarly high as today, would become as much salt in the oceans be that higher life forms could no longer exist. Actually, there are processes that remove the salt and out of the ocean. For this purpose, on the one part of the formation of lagoons and enclosed sea basins in which seawater collected evaporates and thus form thick salt deposits. On the formation of such lagoons reef-building organisms are involved. This, too, is thus according to Lovelock, a process in which the community of the living being itself ensures that their living conditions are maintained. On the other methylene chloride and methyl iodide are produced by seaweeds and then released into the atmosphere. Also by this biological process salt constituents such as chlorine are removed from the sea water.
Counter some of these arguments recent research. The theory of the primeval ocean has become saltier always with time, could not be confirmed. Apparently, the salt content of more than a billion years was already higher than today - what could have been one reason that it took so long to be higher life forms developed in the oceans.
History
The origins of the Gaia hypothesis lie in the scientific background of the two scientists James Lovelock and Lynn Margulis. The geochemist Lovelock worked intensively with how the biosphere has changed the atmosphere in the course of the earth and still changed. One result of these considerations, the CLAW hypothesis, which was formulated in the late 1980s and refers to the relationship between phytoplankton and global climate. " These phenomena ," Lovelock wrote, " can only be understood if the planet as a single living organism is considered. " The term " Gaia hypothesis " is based on a suggestion of the writer William Golding, who lived in the same village as Lovelock ( Bowerchalke, Wiltshire, UK). Golding's proposal was based on Gea, an alternate spelling for the name of the Greek goddess, which is used as a prefix in geology, geophysics and geochemistry. Golding themed " Gaia Mater" in 1983 in his Nobel Prize acceptance speech.
The biologist Lynn Margulis, in turn, is considered one of the founders of the endosymbiont theory, according to which the cells are present once emerged from the symbiosis of independent organisms. The idea of symbiosis has shaped their entire biological thinking. " Gaia ," said Greg Hinkle (student of Lynn Margulis and now a professor ), " symbiosis of space considered " was. Finally, the Gaia hypothesis implies that the whole of the organisms to form a larger body of the earth to a certain extent in symbiosis.
Several scientific symposia have dealt with the Gaia theory, the most recent of which, 2006 in Arlington. Some scientists have now formulated a counter-thesis, in which they describe the biosphere rather than Medea, since in certain cases can also be self-destructive. As evidence they lead among other things to younger findings, which produced by bacteria halogenated hydrocarbons could have caused the mass extinction at the Permian-Triassic boundary.
Understanding of life
The Gaia hypothesis is a system- theoretical understanding of life is based. A living being is thus an open and entropy - producing system, which can be reactive and self-organizing to adapt to its environment in a way that it is able to keep its entropy dynamically below its maximum entropy by entropy export. A central characteristic of living things is also the reproduction.
Modeling
To substantiate the Gaia hypothesis and to counter the criticism that it was purely teleological Lovelock created with Daisyworld a simple computer simulation, in which life in a self-regulating process, despite changing external parameters maintain constant environmental conditions on a planet.
Effect and spiritual transfiguration
Since the formulation is the hypothesis in the discussion between criticism and fascination with the image that it conveys.
The founder of the Gaia hypothesis, James Lovelock, comments:
As part of the ecology movement, the Gaia hypothesis has found many followers in the hippie and New Age Movement. Here the earth is sometimes portrayed as " soulful " organism - like a Earth Goddess - punished and rewarded. Thus, processes of an ecosystem is given a meaning which leads to teleological explanation attempts. The founder of the hypothesis have always distanced himself from such an interpretation of their hypothesis.