issue 193 - March 1989
Life in the balance
The Earth is uniquely suited to sustaining life of many kinds. Patrick Rivers
explains the principles on which this global organization is based.
In comparison with its sister planets, our own blue-green Earth is a unique haven for life that we take far too much for granted. The configuration of conditions on Earth, exactly right for life, are rare and miraculously ordered. Lying at the optimum distance from the sun, our planet is neither too hot nor too cold for life to arise and continue. The speed at which the Earth spins on its axis is equally critical, for by rotating once every 24 hours it retains most of each day's precious warmth.
Earth is positioned at such a distance that the sun's rays arrive with the precise amount of energy needed to maintain life. Our atmosphere is unique within the solar system. Other planets are surrounded by poison brews such as methane, ammonia and carbon dioxide. Earth in contrast is enveloped in a benign mixture of oxygen and inert nitrogen, together with low concentrations of carbon dioxide and water vapour: all the gases that life requires. It is indeed a blessed planet.
Into this scene, when the time seemed right, humankind entered and became the vessel for the unprecedented phenomenon of consciousness: the miraculous state of self-awareness. Yet evolution, not for the first time, had blundered. As a species we were not yet ready to be the vessel for so powerful a phenomenon, and so instead of employing the gift to enhance Earthly life, we set about destroying it.
The Gaia hypothesis
So accustomed have we now become to treating Mother Earth as something between treasure trove, casino, and woman to be conquered, that a view suggesting we approach it gently, or which challenges our role of manager or steward, is naturally threatening. This being so, we are sure to feel uneasy with a concept that Earth and the thin green mantle laid upon it act as if they were a single, if complex, living organism - with needs just like any other living being. Moreover it would run contrary to prevailing religious belief to suppose that Earth itself and its green mantle, the biosphere, helped to create the exceptional conditions that made life possible in the beginning.
This revolutionary concept was formulated in 1970 by the British inventor and geochemist James Lovelock, while he was working with NASA's space programme. He named it the Gaia hypothesis after the mythological Greek Earth goddess, and it has been the subject of serious if controversial study and speculation ever since. This hypothesis challenges the conventional view that life exists on Earth only because material conditions just happen to be right for it. Mystical though it may seem, hypothetical though it remains, its underlying premises seem to have a sound scientific base.
Intensive comparison of Mars with Earth suggested to James Lovelock that '.the entire range of living matter on Earth, from whales to viruses, and from oaks to algae, could in many ways be regarded as a single living entity, capable of manipulating Earth's atmosphere to suit its overall needs, and endowed with faculties and powers far beyond its constituent parts'.
It was already known that life itself had played a major role over three billion years ago in creating conditions on Earth suitable for it to flourish and blossom into all the myriad complex forms we know today. The very first simple cells of life were bacteria and algae, unable to breathe oxygen. Instead they actually produced oxygen as a waste product from the process of photosynthesis. Over a period of a billion years or so, this oxygen combined with minerals to form oxides. When the minerals could absorb no more oxygen, the rest escaped into the atmosphere, some of it to form a high-altitude layer of ozone.
This amounted to a curious turn of events. Until then the sun's ultra-violet light had helped to synthesize the amino acids of primitive life. To more complex and susceptible oxygen-breathing life forms, however, the ultra-violet light posed a lethal threat. The ozone layer neutralized this threat by acting as a shield. In consequence evolution had no need to stop at the level of anaerobic bacteria and algae, but was able to achieve the efflorescence of life we know today.
To assume that all the elaborate and interrelated conditions for life to evolve and continue could be attributed to no more than sheer coincidence was too much for James Lovelock to swallow. He took the intriguing implications a stage further. He posed the hypothesis that life itself continued the evolutionary process by co-operatively carrying out control functions necessary to maintain the right conditions for life. The process whereby control is achieved by immediate and automatic reactions is known as cybernetics; the steady state it accomplishes is called homeostasis. These two processes go on within our own bodies every moment of our lives. Gaia is no different.
The ozone layer is one such homeostatic mechanism. Four others may briefly be described: oxygen, temperature, acidity and salt.
The mechanism which regulates the amount of oxygen in the air is perhaps the most important. Gaia, Lovelock's living Earth, keeps the oxygen level constant at exactly 21 per cent: any less and life as we know it would not survive; any more and spontaneous combustion would ensue. Forest fires would burn until every tree had been reduced to ash.
Living plants play a major role in regulating oxygen and carbon dioxide levels. By the amazing process of photosynthesis, trees and other plants are able to feed directly from sunlight: overall, taking in carbon dioxide and producing oxygen as a by-product. Their constant exchange of these gases contributes to the global cycling of gases through air, ocean, rocks and soil. Of all Earth's plants, the 25,000 species of marine algae are the most crucial. Dominated by microscopic plankton, they release from the oceans a vast proportion of the atmosphere's oxygen.
The second regulating mechanism involves the Earth's temperature. As in our own bodies, a stable temperature is also important if life on Earth is to continue. Despite dramatic cosmic changes, the Earth's surface temperature has stayed within tolerable limits for hundreds of millions of years. And just as several agents are responsible for keeping our own temperature constant, so many are involved in stabilizing the Earth's.
Unlike any of its sisters, Earth is an ocean planet. Covering roughly four-fifths of its surface, the oceans help to stabilize its temperature. Within them are found most of its life forms and, but for the unique properties of its atmosphere, Earth would know no other life, for the sea would lie inert, the land arid. Yet because the Earth's atmosphere has the remarkable capacity to absorb evaporating water, the oceans have been able to share water with the land. Watered by rain and snow, the land teems with all the life forms we know.
Within the Earth's atmosphere a small proportion of carbon dioxide acts as an insulating blanket, trapping much of the heat energy radiated from Earth that would otherwise be lost in space - the 'greenhouse effect'. Plants too play a significant role, for water vapour helps to stabilize temperature. Transpiration from the leaves of plants adds to the humidity, which encourages rain to fall - an effect that can be witnessed dramatically in tropical forests where rain stops short at the very point that the lush greenery ends. Cloud and the greenery of plants and forests together affect Earth's albedo, a measure of its 'shininess'. This too affects its temperature by its capacity to reflect the sun's light and heat back into space.
A third mechanism maintains the rain's acidity. For soil to make available the mineral salts that plants need for nourishment, the rain falling on it must be sufficiently acid: too little and the nourishment remains locked up; too much and plant life succumbs. Normally the right acidity is maintained by the presence of ammonia in the air in small proportions kept constant by Gaian means.
Albedo: a measure of the 'shininess' of an object such as a planet. This is the ratio of the intensity of light reflected from the object to that of the light it receives from the sun.
Cybernetics: control of a system by automatic responses.
Ecosystem: a system of interactions between species and their environment.
Gaia hypothesis: the suggestion that the entire range of living matter on earth can be regarded as a single entity, capable of manipulating its environment to suit its needs.
Homeostasis: the maintenance of equilibrium within a system by a tendency to compensate for disruptive changes.
Photosynthesis: using light energy to combine carbon dioxide and water, producing organic matter and releasing oxygen.
Our last example involves the oceans. Life began in the oceans. Moreover they not only support at least half the total weight of life on Earth today, but they play a major role in maintaining life on land, in regulating climate and in moderating excesses such as those brought on by industrial man.
The health of the oceans, so demonstrably essential for life, depends principally on the amount of salt they contain. Over time so much salt has been washed down by rivers that now the oceans should have become as intolerant of life as the 'closed cycle' Dead Sea: nevertheless ocean salinity stays at the 3.4 per cent maximum that life can stand. Had it ever risen even to four per cent, life could not have evolved as it has; if it had soared to six per cent even briefly, ocean life would have promptly succumbed. Since so much of Earth's living matter is found in the sea, it may be conjectured that here lies the key to whatever regulates salt levels.
The oceans too have their complex systems of currents, tides and food chains, transporting the sun's energy to the depths and distributing fertility to all regions. The oceans interact with the air and land, renewing the air's spent oxygen and absorbing its excess carbon dioxide, as well as receiving the land's excess fertility. The whole functions as one giant system, perfected over aeons, sustainable for as long as the sun shines, in controlled balance and charged with incomprehensible order.
In exploiting Earth we have interfered with the critical physical and living cycles in all three elements: air, land and sea. In doing so we have placed at risk the balance which Gaia endeavours to maintain so that life may continue. On land we have drastically reduced the green mantle of forests and other plant life, and the destruction is proceeding faster than ever before. This process has been accelerated by acid rain, caused chiefly by sulphur dioxide emissions from fossil fuel power stations and car exhausts.
Through years of burning fossil fuel and deliberate forest fires, we have raised the amount of carbon dioxide in the air by 12 per cent in less than a century. All these actions could raise Earth's temperature and seriously affect climates everywhere. It remains to be seen how Gaia attempts to restore equilibrium.
Since ocean life plays a major role in preserving stability, we should take heed of warnings from organizations like Greenpeace and Friends of the Earth. To exterminate the whales, dolphins and porpoises, to over-farm the rich continental shelves, to demean the ocean by dumping radioactive waste and other toxic man-made rubbish regardless of consequences . . . such acts could be pushing Gaia too far.
Contrary to general belief, the natural living world is not some disordered, distant jungle. Despite superficial chaos it is subject to strict laws which sustain it over time and keep it in balance.
The principles that maintain order in the natural living world could be expressed in purely scientific terms, but then only the minority who are scientifically disposed would trouble to read them. The summary below attempts to convey in simple language the excellence of the natural design that surrounds us and how it comes about.
The living world is divided into ecosystems, all connected to each other. An ecosystem comprises many different species, each with its own niche, and all living off a common environment which functions as a more or less self-sustaining unit. An ecosystem might comprise a substantial area of marshland with its unique, self-sustaining population of fish, birds, animals, insects, plants and bacteria; or a tropical rainforest, similarly teeming with life; or a 'meadow' of waving seaweed, rich in fish and crustaceans.
It has long been held that the greater the number of different species that there are in an ecosystem, the more it is able to withstand damage, for diversity from Nature's point of view is a kind of insurance policy against the loss of any one species through over-swift or excessive change. The principle that diversity means stability has recently been challenged by reference to specific examples, but until a satisfactory computer model of the global ecosystem has been devised, it would seem prudent to follow common sense and play safe.
If there should be a change so sudden or violent that an ecosystem collapses, the stability of ecosystems everywhere is affected - just as they are affected by the expansion of any ecosystem. If an ecosystem - or indeed any individual within it - gains an undue advantage over others, it does so at some cost to the rest. Biologist and ecologist Barry Commoner has neatly summed this up: 'There is no such thing as a free lunch'. Payment cannot be avoided, merely delayed.
History abounds with examples of the consequences of ignoring connections. When the Romans made a desert of North Africa by using the land to grow ever more grain, they affected the climate from the Middle East to the Gulf of Mexico, and even to Britain, right through to the present day.
The splendour that is Venice was responsible for the eventual destruction of Mediterranean forests from Spain to Greece and as far north as the Baltic, felled for shipbuilding and for sunken piles to support its island palaces.
So much for the past. Today, agribusiness farmers boost crop growth with fertilizers and poisonous sprays that leach into streams and underground reservoirs so that drinking water becomes contaminated with potentially carcinogenic nitrates and other toxins. For this unfair advantage both town and country dwellers pay dearly. Eventually the farmers' own families share in the misery: a case of 'Prosper now, pay later'.
2. Unique niches
Within the overall system, each species occupies its own unique niche. A niche in this context is not specifically a crevice in a rock or a cleft in a tree trunk. It is not so much a physical location as a vocation. Each species has a job to do, basically that of feeding itself and reproducing, and each does its work in a unique way. The 'higher' species have the extra task of rearing their young and once again each has its own way of doing so. The uniqueness of each species grants it a specific space in the complex society of life, not unlike a piece in a jigsaw puzzle.
A niche is multi-dimensional. Within its niche an animal, insect or fish seeks the specific diet it needs, and a plant the soil type it thrives on. The niche may also provide the most suitable microclimate for a species, as well as the space and the amount of water and other resources it needs. Here too it must be able to reproduce itself with a fair degree of safety from predators, while enjoying whatever shelter from the elements that it requires. (It is of course the ability to reproduce that chiefly distinguishes living matter from dead matter.) Each species over time becomes uniquely adapted to life within its niche and suffers if it is forced to deviate from its lifestyle. Sometimes a species can live outside its niche, but since such an existence can be harsh and subject to stress, the species seldom thrives for long.
The niche allows many different species, predator and prey, large and small, weak and strong, to partition resources and live side by side. Since each has its own job to do, its own way of breeding, its own specific diet and its own way out of danger, each species is able to thrive. As the ecologist Paul Colinvaugh explains, by obeying the principle of muted competition, territorial animals respect the neighbourhood of others. It is the system of niches that enables foxes, rabbits, reptiles, birds and insects to inhabit the same patch of heathland in relative harmony. From time to time individual members may get eaten, but their numbers ensure that the species as a whole survives.
To 'trespass' on the niche of another is to come into direct as opposed to muted competition and so run a greater risk of being eaten. Since every individual is food for the members of one or more other species, life is naturally hazardous. Nature is not cruel in the way humankind is however. All this killing is solely for survival; deliberate cruelty is confined to our own species. When a cat plays with a mouse it is only 'keeping its paw in' - practising for the next hunt.
The system of niches accounts for the amazing order that prevails despite the world's seeming chaos. It enables most plants and animals to live their lives without stress, largely free from the constant risk of being eaten. There is not the perpetual massacre that most of us imagine but peaceful co-existence: a muted struggle in which each species devises 'tricks' and strategies of opportunism to avoid wasting energy in futile, all-out competition.
Humankind is probably the only species to ignore the principle of interdependence and leave its niche of hunter-gatherer to poach systematically on the niches of others. As a species we are 'swarming'. We have relinquished muted competition in favour of unashamed aggression. It is a situation that the whole will not tolerate indefinitely. Paul Colinvaugh points out that we humans enjoy little peaceful coexistence, either with our own kind or with the rest of Nature. We are engaged in a deadly struggle and so, even though some may fare well, the majority must expect a harsh existence.
Each living organism has evolved over time to be just about right for its niche, though never more than adequately so. The giraffe's neck is not really excessively long but just right for browsing parts of the tree that other animals cannot reach. If circumstances change, species evolve and change as much as is necessary to survive, but again no more than is adequate. Those that fail become extinct.
In the natural world, individuals normally kill others only from necessity, to defend themselves, their young or their territory or, if carnivores, when hungry, but never more than they need. In ordinary circumstances without pressures they rarely kill members of their own species, though they will if overcrowding occurs. We should not be too hard on the fox that kills all the henhouse poultry in one go: in Nature the hens would all be roosting high up beyond his reach. The first bird's startled cry would despatch any other foolish ones into the trees, and the fox would be lucky if he took more than one; any blame lies with the farmer for creating a situation for which the fox isn't programmed.
When members of any of the more intelligent species are in dispute, ritualized, non-mortal aggression is the common alternative to killing, intended as a warning or a gesture of supremacy, at most a wrestling match where the loser is allowed to escape. The spectacular clash of skulls of reindeer, rams or billy goats is a familiar example.
Within the whole there is never any lasting surplus. Waste, as we humans understand the word, is unknown. Anything left over by one individual - whether inedible husks, faeces, discarded skin or corpse - is delectable to another species. What one discards becomes another's nourishment. Vultures and dung beetles may not be cuddly but they do an invaluable job by cleaning up carrion and cow pats, while the dreaded woodworms helpfully turn fallen branches into good soil when nobody is around to gather firewood.
4. Response to change and stress
Change is constant. Any time that the environment or niche of any species materially changes, the species is subjected to stress. The new situation then represents a challenge that calls for an appropriate response. If the species is adaptable enough to make the necessary change, the stress disappears and all is well. However if it cannot, possibly because the change in its environment was too swift or violent for it, the species becomes so stressed that it either fails to breed or becomes easy prey to others until it is reduced to extinction. If this happens, other species then move into its niche and overall balance is usually restored. Sometimes however an ecosystem maybe invaded by a species so aggressive that it takes over to the detriment of others. This is known as opportunism and happened when Europe colonized most of the world and introduced all manner of foreign species, from rats and mosquitoes to prickly pears. Original balance is then never restored.
Adaptability is a highly-prized survival mechanism. As a species well endowed with it, we have been able to spread throughout the globe. Yet it can be a gun that fires both ways: it can create a population explosion with subsequent unpleasant destabilizing measures; and it can enable a species to survive in a degraded form, as is now evident in our willingness to accept a lower quality of life rather than make changes to improve it. In contrast, the popular giant panda and the koala bear are both endangered species because they have evolved to feed on only one species of plant - bamboo and one kind of eucalyptus respectively. They are only endangered because we are encroaching on their habits and they cannot switch to alternative diets.
5. The cycle of life
Constant change means that both living and dead matter is for ever being rearranged all over the face of the Earth. Nothing ever disappears, however, it is simply moved to somewhere else or converted into some other substance. A growing tree harbours a hundred species of bird, animal and insect whose droppings help it grow; someone fells the tree, burns it, the smoke settles miles away; the ash is dug into the garden to grow' vegetables which are eaten; she or he dies, is buried: a tree is planted above the grave. . . and so the cycle is repeated.
In the web of life everything is connected to everything else. In a never ending cycle of birth, death, decay and rebirth there is continuous replenishment and renewal. For three billion years, life on Earth has survived natural disasters both from its molten interior and from outer space. Over time the whole has maintained its crucial stability and balance. Life on Earth - if we would only leave it alone to look after itself - could continue for as long as the sun shines.
6. Everything is connected
The entire network acts like an amplifier. Because of a 'knock-on' effect, a disturbance in one place can cause considerable, distant and possibly long-delayed effects elsewhere.
When Egypt's Aswan dam was built, the trapped waters denied the once-fertile lower plains their annual silt-laden flood. The deprivation had two major effects. Not only did it cost Egypt millions of square metres of cropland, it also cost the eastern Mediterranean its great beds of marine algae, and with them Egypt's huge dependent sardine catch. Here the 'knock-on' effect contributed significantly to the near-extinction of this inland sea's whole fish population. It also forced Egypt to use much of the dam's hydro-electric power to manufacture fertilizers as partial substitutes for the lost silt, which is now displacing water in the dam. Clearly no one foresaw the connections.
The principle is not always based on erroneous technology. Trendy gourmets throughout the West have developed such a penchant for frogs legs that Bangladesh and Indonesia alone export millions of kilograms a year. Now the paddy fields need heavy spraying with toxic pesticides to cope with the plagues of insect predators that the inhumanely-killed frogs once effectively kept in check. Rice gourmets beware.
Limits to growth
There are constraints that operate to limit the growth of individuals and the species they belong to, for nothing - not even a cancerous growth - can keep on growing for ever: it is checked, either by the host's immune system or by her or his eventual death. Some constraints on growth are imposed from within individuals, while others work from outside. If, despite this, any one species becomes so dominant that it poses a threat to the rest, the whole eventually takes action to reduce the offending species' numbers so that balance may reign once more. This principle would operate if the world became so overpopulated by humans that they commandeered every possible acre of land for the sole purpose of feeding themselves. The most likely remedies would then be death-dealing famine and accompanying disease.
For the top job of Earth Manager humankind's curriculum vitae is not impressive, as any objective look at our past performance reveals. If we search for evidence that we have added anything worthwhile to Earth's variety, and diversity over the past 10,000 years or so, we draw an embarrassing blank. We have made no improvements to the whole. Any changes we may have made have been no more than local or temporary. We have indeed bred new strains of farm crops and livestock, but since they have widely supplanted original strains, their introduction has been made at the expense of overall diversity. The picture worldwide is one of alarming decline, gathering momentum with every year. Deserts are advancing, forests receding, soil eroding and fertility deteriorating as land, sea and air becoming ever more polluted. Moreover - for the first time in our history - the total number of species on Earth has decreased. Throughout the evolution of life on Earth, species have become extinct at the rate of one a year; now, under our management the rate is one a day, expected to accelerate to one every hour. It is estimated that by the turn of the century two million species of plants, animals, birds and reptiles will be gone forever.
From Earth's viewpoint the value of any species is not its intelligence, its beauty, its size or its engineering accomplishments but only' its contribution to the good of the whole - of all life. From this vantage point humankind takes on a different aspect. We get a glimpse of ourselves as others see us, and it is not at all flattering. It implies that we can claim no special status on Earth apart from our awareness.
Renewal is paramount. Replenishment and renewal are implicit in the cycle of birth-life-death-rebirth. Together they are the means by which life on Earth maintains itself, the key to continuity, the chief hope for our future.
|This article is adapted from The Stolen Future: How to Rescue the Earth for our Children by Patrick Rivers, recently published by Green Print, an imprint of the Merlin Press, 10 Malden Road, London NW5 3HR, price £5.95. Green Print books are available in Canada from DEC books (Toronto) and in Australia from Cambridge University Press (Oakleigh, Victoria).|