|'The Gaia hypothesis is an ecological
hypothesis proposing that the biosphere and the physical components of
the Earth (atmosphere, cryosphere, hydrosphere and lithosphere) are closely
integrated to form a complex interacting system that maintains the climatic
and biogeochemical conditions on Earth in a preferred homeostasis.
Originally proposed by James Lovelock as the earth feedback hypothesis,
it was named the Gaia Hypothesis after the Greek supreme goddess of Earth.
The hypothesis is frequently described as viewing the Earth as a single
organism. Lovelock and other supporters of the idea now call it Gaia theory,
regarding it as a scientific theory and not mere hypothesis, since they
believe it has passed predictive tests."
||-an ecological hypothesis
-proposed by Dr. James Lovelock
-The hypothesis is frequently described
as viewing the Earth as a single organism.
-A hypothesis becomes a theory by passing
|Formulation of the Gaia Hypothesis
||- it started with the idea of the search
for evidence of extra-terrestrial life
- NASA targeted Mars as more likely
- Lovelock predicted the absence of life
- Martian atmosphere was chemically
dead, showed no change compared to earth's which is active and changing
|Why was the Earth different?
|- Venus atmosphere is 95-96%
carbon dioxide, 3-4% nitrogen, with traces of oxygen, argon
- Mars is 95.3% carbon dioxide,
2.7% nitrogen, 1.6% argon, only 0.15% oxygen and only 0.03% water.
- Earth's is 77% nitrogen,
21% oxygen with traces of carbon dioxide, methane and argon.
- the atmospheric gases which comprise
the Earth's atmosphere is unique in our solar system.
|Lovelock asked the question ... so what
happened on Earth?
||- did it start with a different makeup?
- did something happen to change earths
atmosphere? Especially so little CO2, so much oxygen and nitrogen?
- What complex processes are at work maybe
for billions of years that would explain this uniqueness? What is the driving
force to maintain such a unique combination?
|In the late 1960's Lovelock considered
the beginnings of life on Earth.
||1. The earliest of life forms existed
in the ancient oceans
2. They were the smallest and the simplest
- bacteria and algae, there is fossil evidence for these now
3. almost 3 billion years ago, bacteria
and photosynthetic algae began removing/using the carbon dioxide from the
atmosphere. A lot went into energy molecules like glucose and other sugars,
proteins, DNA etc... but huge quantities were permanently LOCKED UP in
calcium carbonate.. better known as limestone.
4. AT THE SAME TIME, cyanobacteria and
then algae photosynthesized and released oxygen.
5. over vast geological time spans - the
atmosphere went from a typical high carbon dioxide or the other planets
towards a mixture of nitrogen and oxygen. And oxygen based metabolism or
aerobic combustion was REALLY the monolith in the 2001. It was the quantum
leap of evolution.
6. This was the first time somebody
put together the idea that LIFE could profoundly change the physical planet.
|Why Gaia Hypothesis ?
||- Lovelock, began to formulate the explanation/
methods by which Earth was transfigured and transformed by a self evolving
and self regulating living system.
- "Gaia" - after the Greek goddess who
drew the living world forth from Chaos
|The scientific community was not happy.
Where's the proof?
|- Up until this point, there was a very
STATIC view of the Earth. The physical Earth simply was and life adapted
to WHAT WAS ... but life did not CHANGE the physical Earth.
- By 1979 James Lovelock had published
some of his ideas in a first book "Gaia: A New Look at Life on Earth" in
which the statement of the specification of the Gaia Hypothesis had become
somewhat better defined.
|"'...the physical and chemical condition
of the surface of the Earth, of the atmosphere, and of the oceans has been
and is actively made fit and comfortable by the presence of life itself.
This is in contrast to the conventional wisdom which held that life adapted
to the planetary conditions as it and they evolved their separate ways.''
||- has been and is actively made fit and
comfortable by the presence of life itself. The coevolution of physical
- in contrast to the prevailing idea that
life adapted to the planetary conditions as is and evolved to adapt
|"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... [Gaia can be defined] as a
complex entity involving the Earth's biosphere, atmosphere, oceans, and
soil; the totality constituting a feedback of cybernetic systems which
seeks an optimal physical and chemical environment for life on this planet."
||- this is a very important concept, that
life itself on Earth regulates and moderates the physical Earth to make
it habitable. An example is the response by plants to increased CO2 in
the air which results in an increased growth of plants that lock up more
|* "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?"
||- of course, what this brings up is that
intelligence is an evolutionary adaptation that can be used to moderate
the physical world, to change it to make life more possible. Certainly
the evolution of high level intelligence made it possible to handle and
control fire, to build housing to keep us warm, to make clothing to keep
us warm and let us spread out into very INHOSPITABLE parts of the globe.
Irrigation allows us to grow food which wouldnt be able to grow there without
human intervention. Humans as a species have been very successful terriformers,
changing every aspect of the planet.
|* "The name of the living planet, Gaia,
is not a synonym for the biosphere - that part of the Earth where living
things are seen normally to exist. Still less is Gaia the same as the biota,
which is simply the collection of all individual living organisms. The
biota and the biosphere taken together form a part but not all of Gaia.
Just as the shell is part of the snail, so the rocks, the air, and the
oceans are part of Gaia. Gaia, as we shall see, has continuity with the
past back to the origins of life, and in the future as long as life persists.
Gaia, as a total planetary being, has properties that are not necessarily
discernible by just knowing individual species or populations of organisms
living together. Specifically, 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
||The Ages of Gaia: 1988] A Biography of
Our Living Earth
- the interconnectedness of the all the
natural terrestrial systems - not just the atmosphere - is beginning to
|Lovelock goes on to say ...
* "You may find it hard to swallow the
notion that anything as large and apparently inanimate as the Earth is
alive. Surely, you may say, the Earth is almost wholly rock, and nearly
all incandescent with heat. The difficulty can be lessened if you let the
image of a giant redwood tree enter your mind. The tree undoubtedly is
alive, yet 99% of it is dead. The great tree is an ancient spire of dead
wood, made of lignin and cellulose by the ancestors of the thin layer of
living cells which constitute its bark. How like the Earth, and more so
when we realize that many of the atoms of the rocks far down into the magma
were once part of the ancestral life of which we all have come."
- A MODEL system for GAIA
- a redwood tree is 99% dead, but the
tree is alive.
|SCIENTIST WERE NOT HAPPY. For a start,
it implied that studying the "parts" could never show the whole picture.
Like saying we cant study birds without also studying the trees they live
in, the food they eat .. but on a much larger scale. And that LARGE scale
was extremely interdisciplinary.
"Theoretical ecology is enlarged. By taking
the species and their physical environment together as a single system,
we can, for the first time, build ecological models that are mathematically
stable and yet include large numbers of competing species. In these models
increased diversity among the species leads to better regulation."
|- this theory of complexity is well illustrated
by an examples of not seeing the WHOLE picture
1. killing pest with pesticides that also
kill the prey species that ordinarily control the pests.
2. This leads to having to apply more and
more pesticides as the pests adapt and become resistant. It is the kind
of thinking where there is zero tolerance, rather than understanding there
is an equilibrium and we can only push on it a bit by bringing in more
The first great extinction occurred when
photosynthetic and oxygen producing bacteria killed off all the bacteria
that couldnt tolerate oxygen. This was a CHEMICAL change in the Earths
homeostasis. The oxygen and nitrogen atmosphere is why our skies
Oxygen made it possible for the quantum
leap forward in energy production called respiration. It provided
the energy for the evolution of multicellular organisms.
| Blue green bacteria
||Colonies of bacteria that form the rocks
call Stromatolites. They are "living fossils" and these rocks
are found in the fossil record 3.5 billion years ago.