LIFE ACCORDING TO GAIA
COOPERATION, NOT COMPETITION, MAY DRIVE EVOLUTIONARY DIVERSITY ON
EARTH
In the beginning there were bacteria, simple one-celled creatures that formed
from the
young earth's gas and mineral seas. These primitive organisms quickly
began devouring the
chemical Garden of Eden that surrounded them. They were
fruitful and multiplied, expanding
throughout the oceans and onto the rocky
shores. When the garden began to grow sparse, the
bacteria adapted, mutating
into altered versions of themselves. These creatures thrived as
well.
And then something remarkable happened. Bacteria began to merge with one
another in
cooperative unions. What one bacterium could not do by itself, it
achieved with the aid of
another. They divided up the labors of life, each
partner specializing in different tasks.
Over time, the bacteria that had
entered into mutual alliances, or symbiotic partnerships,
lost their ability to
survive on their own. Eventually, these cohabiting bacteria evolved
into a
dramatically new type of two-part being-the eukaryote, an advanced cell that
carries
within itself a powerhouse of an organ called a nucleus, a specialized
vessel for genes.
The emergence of eukaryotes was a leap in evolutionary
complexity far greater than any that
has occurred since. All the plants and
animals we know today, everything from the daffodil
to the dolphin, developed
from these early symbiotic unions.
Once life on Earth was
omnipresent its power over the environment escalated.
Living things consumed huge amounts
of some atmospheric gases and exhaled
massive amounts of others. Their presence in the
oceans altered the water's
acid and base content. In short, living things were no longer
passive
passengers that merely adapted to physical events like volcanic eruptions and
asteroid
impacts. They were energetic participants in the regulation of their
world. Organisms that
kept the environment hospitable for their progeny
survived; those that didn't became
extinct. Living things and the planet Earth
were constantly interacting and the world had
forever changed.
If this scenario sounds unfamiliar, it shouldn't be surprising. It is
part of a
daring theory of nature known as the Gaia hypothesis. Proposed by British
scientist
James Lovelock some 20 years ago, the Gaia hypothesis proposes that
all living things and
the chemical and physical environment in which they live
work together like the parts of
one vast organism. Ultimately, Lovelock says,
this "composite organism" manipulates the
air, the land, and the sea to generate
the conditions most suited to supporting life.
"Life
and its environment," Lovelock explains, "constitute a single entity,
which regulates
physical conditions in order to keep the environment at a
comfortable state for the
organisms themselves."
In other words, teamwork between the physical world and the life it
bears is
responsible for the richly diverse living earth. It is Gaia that has kept
global
temperatures from rising high enough or dropping low enough to destroy
all life. It is Gaia
itself that has sustained the atmosphere and the oceans so
that they are suitable for
living organisms.
Lovelock's vision of a cooperative world is bolstered by the work of
American
microbiologist Lynn Margulis, a professor at the University of Massachusetts.
For
Margulis, cooperation among organisms, especially in the form of symbiotic
unions, is the
driving force behind evolution. The bonding of simple bacteria
into a symbiotic union, she
argues, was essential to the evolution of more
sophisticated organisms. And, according to
Margulis, Gaia is the largest
manifestation of the symbiotic process. Like Lovelock, she
believes that the
earth's organisms have joined with physical processes to form one massive
self-regulating organism, Gaia itself.
To say the Gaia hypothesis is controversial is
putting it mildly. When Lovelock
first proposed Gaia (named after the Greek goddess of the
earth), the most
positive response came from New Age types and "ecofreaks" who grabbed on
to the
idea with religious fervor. Here at last, some thought, was a scientific theory
that
implied a purposeful order, even consciousness, in nature. Some scientists
who study the
earth's physical and chemical cycles-they're called Earth systems
scientists-were also
intrigued by Gaia, primarily because of its focus on global
feedback loops, the intricate
cycles that keep oxygen levels, say, or global
temperatures from fluctuating wildly.
But
most of the scientific community dismissed the idea as being, at best,
untestable and, at
worst, poetic nonsense. Gaia's most outspoken critics were
and continue to be
Neo-Darwinists, evolutionary biologists who have blended
Darwin's theory with studies of
modern genetics. Neo-Darwinists see the world
not as a sphere of cooperation, but rather
as a jungle of organisms battling
against one another in a fight for survival. Organisms
evolve, say
Neo-Darwinists, when a genetic mutation makes the organism a better competitor
and thus better at passing along its genes to the next generation.
What led Lovelock and
Margulis to part company with such established scientific
thought? For Lovelock, it all
began with Mars. In the early Sixties NASA asked
Lovelock to participate in the search for
life on the red planet. Lovelock
viewed the space agency's approach-literally searching
the planetary surface for
critters-as arbitrary, something akin to looking for a needle in
a haystack. "I
was sure there was a better way," Lovelock recalls, and, working with NASA
philosopher Dian Hitchcock, he came up with an idea. Instead of searching the
surface of
Mars, he suggested, why not analyze its atmosphere for the metabolic
products of life? If
life existed, the gases produced by photosynthesis and
other biological processes would be
everywhere.
Though NASA did not do it his way (later research would show the agency should
have), the idea set Lovelock to thinking about the difference between dead
planets like
Mars and living ones like the earth.
Back home in England, he began searching scientific
literature for a
"comprehensive definition of life as a physical process" and was shocked
at how
little had been written about it. He formulated his own theory, Gaia, which he
presented
at a scientific conference on the origins of life in 1969. Perhaps,
Lovelock muses, his
paper on Gaia had been poorly presented, because virtually
no one was interested, no one,
that is, but Lynn Margulis. Her own work on
symbiosis had rocked some biological hard hats
a few years earlier, and she
found Lovelock's hypothesis a promising model with which to
understand nature
and evolution.
Since their first meeting in the late Sixties, Lovelock and
Margulis have
willingly suffered the slings and arrows of outraged colleagues for the sake
of
Gaia. They are rebels with a cause who refuse to give in to accepted theory,
believing
that as scientists begin examining nature more carefully, the Gaian
worldview will prevail.
Indeed, a spate of current studies have reinforced their position. Most of the
studies
have come from Earth systems scientists, who are discovering strong
links between the
activity of living things and the physical environment. One
body of research, for example,
indicates that without life, global temperatures
would be as much as 45 degrees C (80
degrees F) higher than they are today. New
York University researcher Tyler Volk and his
colleague David Schwartzman, who
spearheaded the research, examined single-celled ocean
organisms that make
calcium carbonate shells and deposit them at the bottom of the sea.
The shells
absorb carbon, effectively removing it from the atmosphere and burying it in the
ocean. Removing carbon from the atmosphere cools the earth, creating conditions
favorable
to life.
Other research by Volk examines microorganisms that create soil by eating away
at
rock; without all the soil to absorb carbon from the atmosphere, the earth
might
conceivably be 80 degrees F warmer than it is today. "Under those
circumstances," says
Volk, the planet might be ,.uninhabitable for all but the
most primitive microbes."
Similarly,
new research has shown in more detail than ever how symbiotic unions
can create new
organisms. The most startling study really began by accident.
While conducting a series
of experiments on amoebas, single-celled
microorganisms, University of Tennessee scientist
Kwang Jeon noticed that one
batch of the creatures were sick. He studied the ill amoebas
under a microscope
and found that each one was infected with bacteria. Jeon nursed a
number of the
sick organisms back to health and found that the recovering amoebas began to
reproduce even though they were still infected with bacteria. A new symbiotic
organism had
evolved-bacterized amoebas.
Jeon took his study one step further and exchanged nuclei, the
cell organs that
contain the genes, between amoebas that harbored bacteria and those that
did
not. Curiously, the nuclei of noninfected amoebas survived the switch, but the
nuclei
from amoebas that had adapted to their bacterial companions began to die.
When Jeon
injected the ailing amoebas with bacteria, they recovered. The
symbiosis was complete: The
amoebas that had once been infected with bacteria
were now unable to survive without them.
Jeon's discovery of evolution in
progress occurred over a mere 18 months, and it was the
result of a symbiotic
union.
Such studies challenge the Neo-Darwinian view that evolution
occurs primarily
when individual organisms mutate and then pass on those mutations to
offspring
when and only when they confer a competitive advantage. Instead, in the
symbiotic
world the only individuals are primitive bacteria; all other forms of
life, even the most
complex creatures, are communities of bacteria. "Living
systems become embedded in living
systems," explains Gail Fleischaker, a Mellon
fellow at MIT and a former philosopher of
science at Boston University, "and
what survives as a symbiotic relationship is of
necessity a cooperation rather
than a competition."
Lovelock and Margulis are convinced that
as studies supporting Gaia grow in
number, the competitive Neo-Darwinian paradigm will
begin to crumble. In its
place will be a more holistic view of nature in which competition
is supplanted
by cooperation. The living earth will be seen as an integrated system in
which
organisms and the environment coevolve.
How do Neo-Darwinists and other scientists
respond to Gaia and the cooperative
paradigm? Ford Doolittle, a molecular biologist at
Dalhousie University in Nova
Scotia, may sum up the majority opinion when he says, "It
pisses me off. I get
irritated at what I think is fuzzy thinking." There's certainly no
malice in
Doolittle's judgment. He considers Margulis a good friend and a first-rate
biologist.
But he disagrees with her assertions about Gaia and symbiosis.
Like most biologists,
Doolittle questions the role of cooperation in evolution.
The evolutionary process, he
says, could not accommodate the kind of global
cooperation necessary in Gaia. "Natural
selection," he says, "only favors an
organism that has a mutation that allows it to make
more of itself. It does not
favor organisms that behave themselves in a global sense."
Moreover, Doolittle
argues, organisms that unite in a symbiotic union do so because they
gain some
advantage from it. "It is really just selfishness," he says. "Cooperative
efforts
can evolve out of symbiosis, but the driving force is not cooperation."
Other scientists
question what they see as Gaia's basic premise-that life
manipulates the oceans and
atmosphere to benefit itself. "Any change in the
atmosphere and the oceans might be
positive for some species and negative for
others," says Harvard geochemist Heinrich
Holland. "Who is Gaia optimizing the
planet for? The theory sounds something like a
post-Christian view of reality,
in which the hand of God, renamed Gaia, controls the fate
of the earth."
If mainstream scientific opinion is ever to embrace Gaia, Lovelock and
Margulis
will have to produce more rigorous evidence of its existence. In the meantime,
they will continue to struggle in the competitive world of science. It is
doubtful they
will give in. Margulis is accustomed to fighting for what she
believes, and she has
successfully changed scientific thinking in the past. And
Lovelock is quite at ease with
his role as "freelance scientist." With no
position in academe, he says, he has the freedom
to think and do science in his
own way. His laboratory, for instance, is in his home,
Coombe Mill, a small
mud-and-straw cottage set in the Thomas Hardy countryside of
southwestern
England. But in a larger sense his lab is not contained within the walls of
his
small house or even in his 30 acres of meadowland and woods, which he helped to
plant.
It stretches beyond the moors, the mysterious circle of Stonehenge, and
the stony coasts of
Cornwall. It spans the Atlantic Ocean, the deserts of
Africa, the towering Andes, the
Great Barrier Reef. Lovelock's laboratory is
the living earth in all its multifarious
incarnations. It is Gaia and he will
not allow her to be dismissed without a fight.