GAIA Hypothesis, most simply expressed is that: "The Earth
is Alive". The Gaia Hypothesis conjectures that our planet
functions as a single organism that maintains conditions (not
unlike homeostasis in humans) necessary for its survival. Formulated
by James Lovelock in the mid-1960s and published in a book in
1979, this controversial idea has spawned several interesting
ideas and many new areas of research. While this hypothesis is
by no means substantiated, it provides much to ponder about the
symbiosis of physical, chemical, geological, and biological processes
on Earth. In short, it is a very pretty hypothesis.
thing making the theory pretty is that it seemingly forces a conjunction
to occur between what I will call the spiritual and the scientific
belief systems. These belief systems have evolved for centuries
in a sort of détente, with an unspoken agreement to be
non-antagonist to each other (unless one went too far, like Galeleo).
On the spiritual side is the concept of Mother Earth that we have
all heard, simply because it has been very much a part of human
culture (part of our brief existence as a species) in myriad forms.
The concept was central to the religion of Native Americans and
is prominent in Hinduism as the goddess Kali. It is perhaps the
ancient Greeks who had the best metaphor. They named their Earth
goddess Ge or Gaia. An embodiment of the notion of a Mothering
Earth, the source of the living and non-living entities that make
up the Earth. Both Kali and Gaia was gentle, feminine and nurturing,
but also ruthlessly cruel to any who crossed her. Gaia was the
Greek goddess who drew the living world forth from Chaos. The
prefix "ge" in the words geology and geography is taken
from the Greek root for Earth. I believe it is fair to say that
the concept of Mother Earth has been omnipresent and ubiquitous
in human history, and anything but "new age".
sure that most of us can see how such a spiritually framed concept could be difficult
pill for some scientists to swallow, creating controversy. Regardless, the hypothesis
persists. My own viewpoint is that it is not unlike Einstein's search for a Universal
Field Theory, a set of natural laws equally applicable to systems of any size,
from sub-nuclear to cosmic. Let's look of some of the many facets involved in
primary tenet of GAIA is reciprocal interaction between everything on Earth and
the Sun. The sun interacts with life (primarily through photosynthesis) and life
interacts with rocks (primarily in soil making). The Earth's mantle transmits
nutrients to the surface through volcanoes, particularly at spreading ridges,
and reciprocally, the earth's crust feeds the mantle at subduction zones. The
diving plates at subduction zones also make the andesite and granite associated
of Earth is indeed governed and caused by life. Level bottom marine habitats with
soft sediments deeper than wave base, have sediment entirely made by the biota.
Wherever waves affect things (sandstones and the like) sedimentology plays a role,
but not in any fine grained sediment -- these in rocks are fine limestones and
shales. Thus the structure of most marine rocks is biologically determined. Terrestrial
rocks (e.g., the badlands of South Dakota) are a series of soils formed on overbank
deposits and so, being soils, most of the structure is biologically determined.
Hence, most marine and terrestrial rocks derive their structure biologically.
Also, life controls both the much high free oxygen and small free Carbon dioxide
levels of our atmosphere. Our atmosphere composition is inextricably liked to
the atmosphere, that life maintains. Plate tectonics is enabled because the plates
cool and can subduct. Before life diminished the carbon dioxide, the planet was
hot owing in part to a greenhouse effect, suppressing subduction (like the lifeless
planet Venus is today). Hence, plate tectonics also is biologically caused, with
profound importance to life. Degassing is most prominent at spreading ridges and
this would supply much nutriment. Most mountain building is caused by plate tectonics,
so, in effect, life caused plate tectonics.
summary, the GAIA hypothesis says that the temperature, oxidation, state, acidity,
and certain aspects of the rocks and waters are kept constant, and that this homeostasis
is maintained by active feedback processes operated automatically and unconsciously
by the biota.
as Darwin put it:
this planet has gone cycling on according to the fixed law of gravity, from so
simple a beginning endless forms most beautiful and most wonderful have been,
and are being evolved."
to me encompasses what I believe Darwin was thinking as he was awed by an ostensible
interconnectedness of the all the natural terrestrial systems - GAIA, to me is
a very pretty theory.