Book Review: The Ages of Gaia: A Biography of Our Living Earth by
James Lovelock
(Bantam Books 1988, 1990)
This was a fascinating read by the
main proponent of the Gaia Hypothesis. It was his second book about Gaia. Lovelock
is a keen scientist and seems a sensible fellow. The details of what Lovelock
calls ‘geophysiology’ are explored. The earth paired with life can be regarded
as a self-regulating system and life as a self-organizing system. Life seems to
regulate several cyclical chemical systems throughout land, ocean, and
atmosphere. Lovelock is also an inventor and prides himself in being an
independent scientist. One of his main ideas is that evolution is more closely
coupled to the environment than previously acknowledged. In more recent times,
biologists have verified this idea through acknowledgement of evolutionary
mechanisms like “niche construction,” (organisms alter environment to increase
survival chances) which may be as important to evolution as natural selection.
Gaian science is a systems view, with the goal being to promote the overall
health of the system, thus planetary medicine. Much of this book is about
chemistry. He notes that intricate geophysiological regulation systems evolved
without foresight or planning and followed the rules of natural selection.
Lovelock’s first inkling of Gaia
theory was when working on instrumentation design for early NASA moon and
proposed planetary missions. His background being in medicine and biology he
was soon involved in the task of detecting life on other planets and proposed
that the best way to do so was to analyze their atmospheres. Planets with life
would have different atmospheres than planets without life due to the chemical
cycles and metabolism between land, ocean, and atmosphere. Lovelock and his
colleague’s conclusion that Mars was lifeless due to its atmospheric
composition was not at first popular but turned out to be correct. In these
analyses in the early 1960’s the atmosphere of Earth and the beginnings of
determining how it developed was compared to that of Mars. The fact that life
in its various forms developed and regulates our atmosphere through various
chemical cycles led to the development of Gaia theory. Earth as alive was a
component of ancient cosmology and earth as an organism also had scientific
precedents such as those of geologist James Hutton and the Ukrainian scientists
Korolenko and his cousin Vernadsky. Eduard Suess first coined the term
“biosphere” in 1875 when studying the Alps .
Lovelock asserts that geology and biology are so intertwined that they can
hardly be studied separately. He uses the term “geophysiology” to study earth
as a bio-system. Gaia theory is a theory of a living earth – but not in a
comparable sense to a sentient earth in human terms.
He points out that the question:
“What is life?” is not so easy to answer. An organism is a collection of living
things, organs and tissues. Organs are composed of billions of cells. Our very
cells are communities of microorganisms that once lived independently, their
energy-transforming components as mitochondria in the case of animals and in
the case of plants, mitochondria and chloroplasts.
“Life is social. It exists in
communities and collectives.” Physics uses the term colligative to describe properties of collections. Properties like
temperature and pressure are the colligative properties of collections of
molecules rather than of a single molecule. The constant temperature of the human
body, called homeostasis, is a
colligative property. Can ecosystems and Gaia also have colligative properties,
their own homeostasis? This seems likely. Lovelock notes that Gaia is not
synonymous with biosphere. Biology and geology are intertwined. The biosphere
is the place, or part of Earth where life typically exists. The properties of
Gaia, like those of the human body, cannot be discerned through individual
species or populations. The homeostasis of Gaia involves “temperature,
oxidation state, acidity, and certain aspects of the rocks and waters are kept
constant, and that homeostasis is maintained by active feedback processes
operated automatically and unconsciously by the biota.”
The 2nd Law of
Thermodynamics – the conservation of energy – is discussed in terms of entropy,
negentropy, and the production and consumption aspects of life that transfer
energy. Lovelock was influenced by Erwin Schrodinger’s What is Life? where he noted that life exists within boundaries yet
transfers energy with environment beyond those boundaries. In a sort of
hierarchy there are also the boundaries of earth (such as the atmosphere), the
boundaries of ecosystems (forests, etc), of beings (skin, bark), and of cells
(cell membranes). In response to critics from the climate and microbiology
disciplines, Lovelock writes:
“Life has not adapted to an inert
world determined by the dead hand of chemistry and physics. We live in a world
that has been built by our ancestors, ancient and modern, which is continually
maintained by all things alive today.”
Lovelock here mentions two
criticisms of Gaia that he addresses. First is that it is teleological as
Richard Dawkins and Ford Doolittle argued – earth does not really regulate life
as it would have to do it consciously. Second is that biological regulation is
only partial, as climate scientist Stephen Schneider argued. Lovelock notes
that Gaia is a “tightly couple system of life and its environment…” He includes
a whole chapter on his theoretical construct, called Daisyworld, an imaginary world where different colored daisies
evolve as the only life on a planet and alter temperature by their color. He
made this model to show that self-regulation could come about through simple
evolution and energy transfer through feedback mechanisms without any
pre-conscious intent. To me this suggests that he is saying that Gaia is alive
but not conscious. Variables in the Daisyworld model are temperature, solar
luminosity, diversity, and color of the daisies (to absorb or reflect sunlight
in order to regulate climate). He compares his imaginary construct to
mathematical ecology models. He notes the difference between his geophysiology
and theoretical ecology is in the interpretation of perturbation:
“The geophysiologists see
temperature, rainfall, the supply of nutrients, and so on as variables that
might be perturbed. In their view the Gaian system evolved with its physical
and chemical environment and is well able to resist changes of this kind.
Forests of the humid tropics are normally well watered and shaded by their
canopy of clouds; during their existence they are never subjected to prolonged
drought as in a desert region. Theoretical ecologists, on the other hand,
ignore the physical and chemical environment; to them the environment means the
collection of species themselves and a niche is some piece of territory negotiated
among the species, …”
This is important as geophysiology
suggests that the natural link between ecosystem and environment is strong,
such that if that ecosystem were replaced (say tropical rainforests cut down
for agriculture) then such a perturbation would be more difficult to recover
from than the natural climatic variations of the previous ecosystem through
time. Homeostasis would be harder to achieve. This, he says, is in accord with
the “punctuated evolution” ideas (rapid and abrupt periods of evolution) of
Stephen Jay Gould and Niles Eldridge. Gaia theory simply notes that life and
environment evolve together. Biologist Alfred Lotka noted that modeling a whole
system would be simpler than modeling parts of it. It is apparently more
functional to do so as parts of systems are more liable to exhibit chaotic,
non-linear behavior and relationships, says Lovelock. He gives four points about
the Gaian view: 1) Life is a planetary-scale phenomenon, immortal in this sense
with no need to reproduce; 2) partial occupation of a planet is not possible to
sustain life (naturally) as sufficient life is needed to regulate the
environment; 3) Darwinian adaptation notions must be altered to include the
environment, which is tightly coupled to life; 4) models of species and
environment as a single system are mathematically stable and show that
increased diversity leads to better regulation.
Next the Archean (4.5 bya to 2.5
bya) is explored. Life is thought to have begun on earth 3.6 billion years ago.
He makes an interesting point about the ability of life to pass on information
better than any other means, further and with less distortion.
“There is every reason to believe
that we share with the first ancient bacteria a common chemistry, and that the
natural restrictions on the existence of those ancient bacteria tells us what
the environment of the early Earth was like. By transmitting coded messages in
the genetic material of living cells, life acts as a repeater, with each
generation restoring and renewing the message of the specifications of the
chemistry of the early Earth.”
Of course, the message mutated
through time. The Earth as a body likely came from an exploding star, a
supernova. This likely happened around 4.55 bya as dated through the precision
of radioactive decay. Before life came
about the planet was probably beset with violence in the form of multiple
planetesimals and volcanic eruptions. Lovelock and his collaborators note that
the atmosphere of a planet tells more about life than any other thing such as
the rocks or the oceans. Certain components present together like methane and
oxygen are related to life processes. The atmosphere has an immediate effect on
the climate and chemical state of a planet. On earth the chemistry and climate
were obviously favorable for the development of life. A cooler sun was offset
by a thicker blanket of CO2. Lovelock does note that exact conditions in the
Archean are unknown but much can be surmised about the atmosphere and its
components. Much more frequent volcanic eruptions and reaction between ferrous
iron from basaltic rock and water would make hydrogen gas. Hydrogen would have
escaped from the atmosphere until biochemical reactions occurred with it in the
ocean and later it reacted with oxygen in the atmosphere to form water. The
dead bodies of the first microbes likely became food for the next ones as they
were concentrated organic matter. It was also in the Archean that
cyanobacteria, the primary producers, first learned to tap the sunlight for
food by photosythesis. There were also methanogens, scavengers that rearranged
the molecular products of the producers. In Lovelock’s scenario life came
before Gaia. After microbes colonized most of the planet the regulatory
processes affecting the entire biosphere could commence. Photosynthesizers used
up CO2 but made oxygen which was immediately taken up by the oceanic oxidizers,
sulfur and iron. The methanogens utilized organic material and made as waste
products CO2 and methane but only in the absence of oxygen. Lovelock proposes
that this may have produced a layer of methane smog very high in the atmosphere
that had the same effect as the ozone layer does today – filtering ultraviolet light
and stabilizing the stratosphere. He goes into much more detail about possible
Archean atmospheric components but also cautions that his ideas here are quite
speculative. The end of the Archean
about 2.3 bya is marked by a fall in temperature and a sharp rise in
atmospheric oxygen and a disappearance of methane. Planetesimals may have
killed off half of the life on earth many times during the Archean but in each
case life recovered. He thinks the presence of life has led to Earth keeping
the oceans. He talks about much more here: carbon burial, hydrogen sulfide,
anoxic zones, anerobic organisms, denitrification, and free oxygen. He thinks
the point where free oxygen became present in the air signaled the end of the
Archean. Bacteria was the only life in those 2 billion years. It was both
mobile and motile – a single organism throughout the world exchanging
information “as messages encoded on low-molecular-weight chains of nucleic
acids called plasmids.” This was the first known global communication network.
We now come to the Proterozoic
period of the Precambrian era (2.5 bya to 570 mya). As in the Archean the earth
was populated by the bacteria known as prokaryotes but in the now mildly
oxidizing ocean emerged a new form of bacteria, the eukaryotes. “These are the
ancestors of large communities of nucleated cells, like the trees and
ourselves.” The boundary between the Archean and Proterozoic is not set in
stone. Lovelock likes to see it as the point in time when dominance by electron
donors like methane gave way to dominance by electron acceptors like oxygen –
which made the overall environment predominantly oxidizing. Now, instead of an
excess of methane there came to be an excess of oxygen in the air – the
environment went from anoxic to oxic. The composition of the atmosphere
changed. He speculates that a fall in the atmospheric concentration of methane
may have led to a known period of major glaciation 2.3 bya. Free
photosynthetically derived oxygen in the air may have caused hydroxyl radicals
to oxidize atmospheric methane and new consumers may have fed on organic matter
before it could reach the anoxic sediments, denying them of their fodder to
make methane. These would be positive feedbacks for the development of an
oxygenated atmosphere. Lovelock suggests that as oxygen was crucial to the
geophysiological development of the atmosphere so was calcium crucial to the
geophysiological development of the oceans. Oceanic limestone deposits are
apparently an adaptive strategy to quarantine potentially toxic ionic Calcium.
This was first done by bacteria in the building of stromatolites and is now
remnant in bone and teeth. Biological calcium carbonate deposition may have
powered the endogenic cycle – the
slow cycling of elements from the ocean surface to the crustal rocks and back
again. This may have even spurred plate tectonics from the basalt-eclogite
phase transition near subducting plate margins. This is apparently a
speculative idea not accepted by most geologists but if true it would be
powerful evidence for regulatory activity by living things. Even today there is
new research suggesting that life had regulating effects on atmospheric and
chemicals cycles such as the following geology article that suggests burrowing
animals stabilized oxygen and phosphorus. This is thought to have begun at the
end of the Proterozoic – about 540 mya as burrowing animals evolved. They
affected the rate of carbon burial and the amount of carbon buried affects
oxygen production as Lovelock notes. This sounds a lot like one of Lovelock’s
ideas:
Next he talks about salt
regulation. It is interesting that the salinity of the blood of most living
things is remarkably similar. Too much salt affects cell membranes. Most sea
creatures have evolved internal salt regulating mechanisms. Next he talks about
how vast limestone reefs serves to trap water in lagoons, water which
eventually evaporates and deposits the salts. This is another way oceanic
salinity is regulated. He notes that the evidence for this is strong. He does
note that the links between biomineralization (like biological deposition of
calcium carbonate), salt stress, and plate tectonics are tenuous – but he seems
to favor the idea. The new Proterozoic eukaryotes were communities of cells
that utilized the presence of oxygen. Cyanobacteria are ancestors of the
chloroplasts of plants and trees. Chloroplasts occur in eukaryotes as part of
the community within the membrane in what is called endosymbiosis. The need to transfer genetic information, easier in
the single-celled prokaryotes, now required a new process – sex.
Oxygen concentration affects
growth of organisms and growth of organisms
affect oxygen concentration. Where the lines intersect is the point of
regulation = ~21% atmospheric oxygen – which has apparently been remarkably
consistent – the geology article above suggests that it was helped by burrowing
animals at the end of the Proterozoic when oxygen levels were noted to have
risen to this level.
He gives an interesting account of
a place in southern Africa bout 1.8 bya where
algal mats processed and concentrated uranium isotopes coming from deposits
dissolved in a local stream – that served as a natural nuclear reactor! The
uranium isotope, could only be soluble in the presence of sufficient oxygen
which likely came about in that time period in that place.
We now come to the Phanerozoic which
begins about 570 mya and goes to the present. Soft-bodied cell communities and
skeletons came about just before this time. Reactions of free oxygen with other
elements like carbon and sulfur would lead to acids in the air and increased
weathering of crustal rocks, releasing more nutrients – another positive
feedback , beneficial for life. Lovelock suggests that plants began to make
lignin to detoxify oxygen by phenols reacting with it and locking it in – just
as sea creatures made calcium carbonate to detoxify calcium. In both ways the
poisons are captured and sequestered. In the case of calcium this made for vast
cell communities – stromatolites, reefs. In the case of oxygen sequestering in
these polymers, it allowed the development of plants and animals. Apparently,
it has been shown that below 15% oxygen nothing could burn and above 25% oxygen
it would burn everything – so about 21% is an interesting near-necessity for
many forms of life. The presence of charcoal going back at least 200 mya shows
that it was in this range. Fires themselves could theoretically also regulate oxygen
by regulating carbon burial but there is apparently not enough charcoal in the
rocks to account for this. He does speculate that it could have been regulated
by more flammable trees with more complete combustion that don’t leave much charcoal
Next we come to the carbon cycle.
Life certainly partially regulates carbon and carbon dioxide. It does this by
speeding up the carbon cycle through increasing rates of rock weathering. Rocks
are conveyed from plate margin subduction zones to mid-ocean ridges over
millions of years in a continuous slow cycle. Life takes carbon dioxide from
the air and brings it to the ground where it reacts with calcium silicate in
rocks to form silicic acid and calcium carbonate which in turn are carried by
streams back to the oceans to be used as shells then dropped on the sea floor
to be subducted. Lovelock suggests that the most abundant vegetation occurs
with the least atmospheric carbon dioxide - in periods of glaciation – which he
suggests are the healthiest periods of Gaia. Some of these glacial periods have
CO2 at the lowest level comfortable for plant life. In the Miocene, just 10 mya
new plants developed that could tolerate lower CO2. These are called C4 plants
and include some grasses. They tolerate the low CO2 periods of glaciation and
are better prepared for the next glaciation. He thinks the glacial periods have
the highest amount of life and the most efficient forms of life. The increasing
heat of the sun and the effect of the Milankovitch cycles may trigger glaciation
which he thinks is a regulating effect – the more normal earth-state with the
inter-glacials like now being less healthy and abnormal. Lower sea level would
mean more fertile ground exposed in the tropics to support tropical forests
which would sequester more carbon and lower CO2. This is all speculative but
very interesting.
Next he considers the sulfur
cycle. Here Lovelock has done some key scientific work. Hydrogen sulfide was
once thought to be emitted from the ocean in sufficient quantity to account for
its uptake of sulfur among life but this is now known not to be the case.
Lovelock invented a homemade gas chromatograph able to detect dimethyl sulfide
and halocarbons (such as CFCs) in parts per trillion. This he took or sent on a
few voyages across oceans to measure it. As an independent scientist he funded
much of the research himself in the early 1970’s. The results of this research
were published in the journal Nature.
He found that halocarbons were persistent in the atmosphere. He also found that
dimethyl sulfide and carbon disulfide were conspicuously present in the oceans.
Dimethyl sulfide is emitted by algae as a result of their salt-regulating
mechanism that involves betaines. The so-called smell of the sea is probably
the smell of dimethyl sulfide. Lovelock’s Gaia theory suggested its abundance
might account for sufficient atmospheric sulfur (as aerosols that eventually
fall back to earth via air currents or rain) to account for the missing sulfur
in the sulfur cycle and subsequent studies have proved this correct. He
speculates on how this salt-regulating mechanism of algae came about through
algae drying out, stranded on ebb tide beaches. Algae also release methyl
iodide which carries iodine to the land which along with sulfur is essential
for land life. The emission of sulfur by algae has also been proposed as an
efficient climate regulating mechanism. Stratospheric sulfur gases from
volcanoes are known to cool the climate as it forms sulfuric acid with water
vapor around small particulate matter (also from volcanoes) that falls much
slower. This cools the climate for a while until the aerosols drop. Some have
suggested that the algae can emit dimethyl sulfide as a climate regulating
mechanism but this is highly speculative. Apparently, it has been found that
the sulfur chemicals related to salt regulation of algae are released
eventually after their death and after it circulates through the ocean – as dimethyl sulfide,
particularly in the “desert” areas of the open ocean – and this makes the
aerosols that react to make sulfuric acid nuclei to form clouds. This increases
wind velocity which mixes the nutrient-depleted surface zones and the
nutrient-rich deeper zones of the upper part of the ocean – so the algae
benefit themselves. The rain also washes out nutrient-rich land dust out of the
air. The clouds also filter ultraviolet radiation. The atmospheric oxidation
product of dimethyl sulfide is methane sulfonic acid which has been found in
ice cores to correlate to global temperature which suggests that cloud cover
and low carbon dioxide acted in unison to cool the earth.
Next he seeks to look at the
problems of Gaia from the perspective of a planetary doctor. Some of this
material is just a bit outdated. He gives an account of global warming from a
late 80’s perspective. He talks about acid rain and how the problem is with
dosage as some is natural. It also depends on where it falls – if on already
acid land it brings the pH too low. He notes that perturbations caused by
humans can upset the Gaian regulatory systems. Acids and other components from
nitrate fertilizers and raw sewage also affects ecosystems, oceans and forests.
Then his discusses ozone and CFCs. As stated earlier he invented an extremely
sensitive gas chromatograph to detect CFCs in parts per trillion. These had
thinned the ozone layer. More problematic is that they are intensely potent
greenhouse gases. Lovelock originally thought that CFCs were harmless – he
calls it a great blunder. He got caught in the politics and notes that the
dangers of ultraviolet radiation are variable and with CFCs as with many other
things the dose makes the poison. It was once thought that unfiltered
ultraviolet light was lethal but experiments have shown that life has ways of
adapting. He also discusses nuclear radiation and ecology. He notes that oxygen
kills us the same way as nuclear radiation does by metabolizing oxidizing free
radicals. Thus, oxygen is a mutagen and a carcinogen that confers on us a
lifespan and we fight the same battle as was fought by life at the end of the
Archean when oxygen began to increase. We evolved antioxidants like vitamin E,
and other chemical neutralizing mechanisms like superoxide dismutase, catalase,
and others to mitigate problems related to oxygen toxicity. He does note that
our vast population of humans has given us the potential to cause harm on a
much greater scale than previously. If there were only a billion people instead
of 7 billion there would be less global warming, less pollution, etc. He
derides “bad farming” as one of the biggest threats to Gaia. By this he means
such things as deforestation for agriculture, intensive monoculture, and
extensive grazing that minimizes diversity and carbon sinks.
In one chapter he examines
imaginary scenarios of making Mars habitable for life. This is all very
speculative and he does think that Mars is probably too dry to support life
even with magnificent engineering feats like making a greenhouse atmosphere by
manufacturing CFCs and unlocking the ice deposits for water – though those ice
deposits may be much less than thought. He suggests that the only way for it
ever to happen is to make it habitable for life and have life do it through its
regulatory mechanisms over millions of years. This is all so very unlikely that
even reading about it is a bit over the top.
The last section is titled God and
Gaia. Since he was often asked much about his religious beliefs he included
this chapter. He states that he was raised among counrty folk, witches, and
Quakers. Though he admires religious festivities he is no religionist but a
scientist. He does see Gaia as both a religious and a scientific concept but
not in terms of any prevailing dogma. I suppose he enshrines mystery a bit,
maybe similar to how Einstein stated it. He sees himself as a positive
agnostic. As a Gaian he does seem to like the idea of a nature goddess, perhaps
like the Virgin Mary is venerated among rural Europeans. He invokes William
James and declares the scientist as inquisitive natural philosopher as religion
enough, without the dogma. I like such a view. Lovelock acknowledges that we
are the polluters, we demand and consume the products and resources that
pollute. He has been accused by environmentalists as pro-industry but he says
he is not. He simply thinks that Gaia is more powerful than what we can do to
her. In extreme circumstances we could destroy our species and many others but
the Gaia will recover.
He compares ideas of a
deterministic and mechanistic universe and those of a self-organizing universe.
He clearly favors the latter:
“It is concerned with the
thermodynamics of the unsteady state of which dissipative structures such as
flames, whirlpools, and life itself are examples.”
He sees the debate as a
continuation of older debates between reductionists and holists and notes that
reductionism will not fade away as a superb method for understanding and
working with the components of things but seeing holistically can also solve
problems and lead to deeper perspectives. He sees science being unnecessarily
polarized by these one or the other views. Reductionism is key to the
scientific method and needs to be free of subjectivity, yet we tread into areas
where it breaks down and holism offers better ways of knowing. Systems are more
than the sum of their parts, he notes. He notes his awe at chaos and non-linear
systems:
“In our guts and in those of other
animals, the ancient world of the Archean lives on. In Gaia, also the ancient
chaotic world of dissipating structures that preceded life still lives on. A
recent and relatively unknown discovery of science is that the fluctuations at
every scale from viscosity to weather can be chaotic. There is no complete
determinism in the Universe;”
Apparently the study of the
thermodynamics of the unsteady state suggests the presence of a self-organizing
universe.
In the epilog he talks about his
home with his wife and pets in the country between Kent
and Cornwall ,
the changing of the local landscape to promote industrial farming and remove
troublesome wild critters, and the accompanying habitat destruction. It is the same in many places.
Lovelock thinks that if we see the
world as a living organism which we are a part, then we will live in harmony
better with it – rather than seeing ourselves as dominant over it or as a mere
tenant of it.
