Living Systems in Evolution
copyright © 1999 by Elisabet Sahtouris
Charles Darwin was an English gentleman scientist who lived during most of the nineteenth century and who traveled far and wide to study nature. Seeing the great variety of plants and animals around the world, he was struck by the way each kind seemed uniquely suited to the place in which it lived. He believed, as had a few other scientists, that all these living things must have changed over time to suit their particular environments so well. This was a novel idea at a time when almost everyone believed that the world itself was unchanging and that God had created all species at the same time, just as they are. How could they have changed? Despite Darwin's careful observations and ideas of likely changes, he had no theory, no way to explain how they could occur.
Nature, he noticed, produced great numbers of seeds and eggs for all kinds of plants and animals, though only few of each kind grew up. Somehow it seemed that only those best suited for survival in their environments -- the fittest of each generation -- grew up to reproduce offspring like themselves. But how could nature recognize and choose them?
Darwin had seen plant and animal breeders choose the fattest grains or the fastest horses of each generation to be the parents of the next generation. This was possible because, in each species, the young were not all exactly alike, but were as varied as human brothers and sisters. By such selection, generation after generation, the breeders changed the species, producing ever fatter grains or faster horses. This was exactly the kind of thing nature seemed to be doing, but it still puzzled him how nature selected the fittest creatures of each generation.
The theory of evolution finally came to him when he read an article about food shortages and starvation. Could it be that all nature's young had to compete for food when there wasn't enough for all? Was this how nature put creatures to the test? If so, then surely the fittest in this competition would pass the test and survive to grow up.
The fittest bears, for instance, would be the ones with heavy coats to keep them warm as they hunted for food in cold places; in warm places bears with lighter coats would more likely survive. Birds with long beaks were the fittest where worms had to be pulled out of holes; birds with short, strong beaks would survive where seeds had to be cracked. The bears or birds born with the fittest coats or beaks would win the struggle for food and grow up to produce babies while others starved or froze or were eaten. Their babies would inherit varying degrees of `fit' coats or beaks, and again the fittest of all would be selected in competition.
Everything seemed clear now. Large numbers in the face of too little food produced competition, and competition led to natural selection. The selection itself was based on the natural variety of creatures, some of which were fitter than others.
In Darwin's time, of course, environments -- such as deserts or mountaintops or sea bottoms -- were seen as places in which living things made their living, not as live parts of a great living planet. Each environment would select for different kinds of fitness in the competition for food, for mates, for the best hiding or nesting places, and so on.
If the wind scattered the seeds of the same plant into different places, a desert would select for young plants that could live on the least water, while a windy mountaintop might select for those with the strongest grip on rocks. Just so, some thick-coated wolves that could do well in cold environments might wander to warmer places and die out while wolves with thinner coats survived.
Offspring of the same original parents might therefore become quite different over many generations as a result of settling in different environments that selected for different body patterns or features. When they became so different that they could no longer mate with each other, they had become different species. Thus Darwin explained the evolution of new species.
In Darwin's theory, then, unexplained accidents of birth that made creatures fit better into their environment were selected for survival and passed on to future generations. Unlucky accidents that made creatures less fit were rejected by natural selection and died out.
Scientists quickly made Darwinian evolution fit the idea of nature-as-mechanism by regarding creatures more or less as wheels fitting the cogs of other wheels in the great clockwork of nature. Some wheels just happened to be made better than others by lucky mechanical accidents during their replacement, or reproduction. The idea of natural competition leading to the survival of the fittest appealed to men who were obsessed with the new social structure of industrial capitalism.
With the advent of genetics, accidents of birth were discovered to reflect changes in genes. When the structure of DNA and its copy process were understood, these accidents were believed to occur on a random basis -- meaning without any pattern -- as DNA copied itself or was damaged. Most biologists today still see accidents, now known to occur in DNA, as the only source of natural variation, despite growing evidence that such accidents are detected and repaired very quickly.
Ever since Darwin, our general view of evolution has been of a battle among individual creatures pitted against one another in competition for inadequate food supplies. Only now are we in a position to understand the Earth as a whole -- a single geobiological dance woven of many changing dancers in complex patterns of interaction and mutual transformation.
Competition and cooperation can both be seen within and among species as they improvise and evolve, unbalance and rebalance the dance. Consider again the spiraling pattern described as unity-> individuation-> competition-> conflict-> negotiation-> resolution-> cooperation-> new levels of unity, and so on. Note that competition and cooperation are different phases of the cycle. Young species tend to grab territory and resources, maximizing the numbers of their offspring to spread themselves where they can. As species encounter each other, conflict develops in the competition for space and resources. Eventually negotiations leading to cooperation prove useful to the competing species and they reach the higher level of unity, as we saw happening in the transformation of monera into protists.
Evolution is this improvised dance of transformation in which ecological balance is worked out again and again. Remember that living things have to change, even to stay the same. They have to renew themselves and adjust to the changes around them. Rabbits evolve together with their habitats, and we might call that the dance of rhabitats! All creatures evolve in concert or connection with all else evolving around them. New levels reached in the unity spiral through phases of competition and cooperation are examples of what we described as mutual consistency. The internal harmony of our evolved multicelled bodies is a good example, but our global society is not, as it is still struggling to get beyond its competitive phase.
It took a century and more after Darwin's theory was published for us to understand that environments are not ready-made places that force their inhabitants to adapt to them, but ecosystems created by living things for living things. All the living things belonging to an ecosystem, from tiny bacteria to the largest plants and animals, are constantly at work balancing their lives with one another as they transform and recycle the materials of the Earth's crust.
Darwin, along with Lamarck, and Wallace, were modern pioneers in showing us that species evolve and attempting explanations of how this could happen. Their theories were a great step forward for science, since religion had put an end to all theorizing about evolution since a few ancient Greek philosophers, such as Anaximander, had thought about it. Anaximander had said that everything forming in nature incurs a debt, which it must repay by dissolving so other things could form -- a marvelous description of evolution through recycling in a single sentence!
Now we can see that Darwinism -- and its updated version, neo-Darwinism -- is a misleading way of seeing nature. The notion of the separateness of each creature, competing with others in its struggle to survive, had well described, and justified, English and American societies' new forms of competitive and exploitative industrial production in a world of scarcity. But we are now beginning to understand that humans must learn to harmonize our ways with those of the rest of nature instead of exploiting it and one another ruthlessly. The social view of individual people pitted against one another in such struggle makes little more sense as an ideal than the notion that our bodies' cells are competing with one another to survive in hostile bodies. It is simply no longer useful or productive to see ourselves as forced to compete with one another to survive in a hostile society, surrounded by hostile nature.
The point here is that we do see ourselves in such competition, not because this is inevitable, but because Western science developed in close harmony with social and political traditions that welcomed these ideas. The Darwinian theory of evolution was applied to forming a society, a social system, designed in accord with, and justified by, the Darwinian concept of nature. If we learn to see evolution as a single holarchy of holons working out the mutual consistency of cooperative health and opportunity, we can set up a social system to match that view.
History may someday record the greatest discovery of twentieth-century science not as nuclear power or electronics, but as the recognition that there is no absolute truth to be discovered about the world -- that scientific theories can be judged only by their usefulness to science and ultimately to all society. Definitions of usefulness often change over time, and thus scientific `truths' must necessarily evolve along with human society.
Neo-Darwinism insists that random accident and natural selection are the sole `mechanisms' of evolution. Yet the self-organized creatures and ecosystems -- habitats -- such as that which we saw evolving through the genetic information exchange web of bacteria, including their negotiated organization of nucleated cells are not readily explained as simple accumulations of lucky accidents. Nor does natural selection amount to a real theory, since it tells us little more than that some creatures die before they reach the age of reproduction. A modern theory of evolution must concern itself with the way in which natural holons are organized and maintained in holarchies, with descriptions of continual interactions among the levels of DNA, organisms and whole ecosystems. It must also deal with the aesthetics of orchids and butterfly wings and dolphins creating bubble rings and other games for the pure joy of it.
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As pointed out earlier, no place on Earth today, not even the barest-looking mountaintop or the deepest part of the sea, has fewer than a thousand different species from various kingdoms -- monera, protists, fungi, plants, and animals. Yet what we humans see as living things are only the largest of the plants and animals -- beings the size of bugs and bushes and beluga whales, creatures on our own size scale. The vast majority of Earth creatures, however, continue to be microscopic monera and protists. Think once again of our rocky planet rearranging itself through chemical activity into a rich network of bacteria and environments that are good homes for bacteria. This is what most of the activity of our living planet is still all about.
The age of protists was a long age of creating amazing diversity in the larger single-celled body forms and lifestyles before multi-celled creatures arose. As Gaian evolution continued, ecosystem holarchies went on transforming themselves, as we will see, into ever larger living bodies grown from single cells: worms and insects, fishes and amphibians, funguses, flowers and trees, reptiles, birds, and mammals. Still, the smallest living creatures are even now those that work hardest to create the environments needed to sustain the larger plants and animals. For that matter, larger creatures are really extensions of the microcosm. As eukaryote cells are evolved from prokaryote cooperatives, multi-celled creatures are later cloned upon them, as we will see.
If we think of every ecosystem holon as a kind of body, we can regard each creature as a cell, each species as an organ with a unique function. Their holon evolves its ecological balance as a whole. We really should talk about co-evolution, rather than evolution, to remind ourselves that no species can or does evolve by itself, but that all must cooperate by adapting to, or negotiating with, the others' steps in the dance of life. Thus they reach mutual consistency with one another and with the rest of their surround. The story of co-evolution is still being put together as we try to understand that creatures are not just passive mechanical cogs in a wheel but active agents in their own evolution, or co-evolutionary process.
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To some extent we can study the co-evolution of species within their present ecosystems and find clues to how they must have co-evolved in the dim past, but we also have many other clues to life's long-ago patterns. Fossils -- the imprints and remains of creatures turned to rock -- are very important clues to what early creatures looked like, especially now that we know how to tell their age and have found fossils of even the most ancient bacteria in rocks, such as the stromatolites they built billions of years ago. Fossils alone cannot prove that one species changed into another, but the fossil record clearly shows that larger, more complicated creatures existed only after smaller, simpler ones had paved the way for their existence.
In Darwin's theory, species change very slowly but steadily as environments select for the tiny accidental changes that make some individuals of each generation slightly fitter than others. Since his time, however, many more fossils have been collected, and we see that most species must have changed in spurts from time to time -- far more quickly than such accidents can explain -- while others have scarcely changed at all, despite the slow, steady stream of accidents they must have endured.
The known rate of DNA accidents seems to have no relationship to the rate of change in creature patterns. Some bacteria living now are like those that lived billions of years ago. Squid and sharks and ants have stayed much as they were hundreds of millions of years ago, as we see clearly in the fossil record. Yet many of these slow-to-change creatures' fellow species in co-evolution, such as ourselves, have become very different modern species.
Species whose genetic plans have hardly changed are like bicycles in a world of jet planes -- they still work very well as they are, yet they have been steps along the way to bigger, more complicated inventions. They are, in a way, living fossils to compare with creatures that apparently continued to change or evolve. It seems that co-evolution has rhythms like any other dance -- some slow, some so fast in comparison that they seem almost to leap from being one kind of creature to being another. We ourselves are a good example of a species that changed very rapidly.
If all living beings were created at once -- as creationists still believe -- then all modern species should have fossil ancestors quite like themselves. But this turns out to be true of only very few creatures larger than monera. There are estimated to be somewhere between three million and ten million species alive today, yet well over 99 percent of all the species that ever lived are now extinct. It is worth noting here that in the times of most rapid extinction it is estimated that the rate was about one species lost every thousand years, while we humans have probably caused the extinction of a million species in the last quarter of this century alone! Many biologists acknowledge the present as the sixth great extinction, as we pointed out earlier.
Now and then fossils give us wonderful clues to change, such as those showing reptiles evolving into birds. The archaeopteryx -- Greek for `ancient-wings' -- was a kind of flying reptile with a horny beak and wings strong enough to propel its big body through the air. Its skeleton looks very much like those of modern birds, and the fossil imprints are so clear we can almost see reptile scales evolving into feathers, front legs into wings, and long snouts into hard beaks. The babies of birds, even today, still hatch from eggs just as their reptile ancestors did.
The fossil and chemical geological records show that dinosaurs and other large creatures of their time died out around sixty million years ago during a period when there were major changes in their environment. Apparently these large creatures could not adjust to big changes in climate caused, it now seems, by the impact of a giant meteor or planetoid. Smaller animals did survive the crisis, but they must have evolved so quickly that none of them left clear fossil records of the gradual changes inferred by Darwinian evolution.
The fossil record alone is simply not adequate to prove modern creatures' lines of descent. In fact, scientists have not found a single clear and complete fossil line of descent for any modern creature, and this has become a major argument used by the creationists, who don't believe in evolution. How can we be so sure that modern creatures actually descended from earlier ones that were quite unlike them?
We have, fortunately, other clues to evolution. For one thing, we can actually see evolutionary changes taking place in some living species. In bacteria, protists, fungi, plants, and animals that reproduce quickly and often, we can follow the changes over many generations. With electron microscopes and other modern instruments we can actually track their changing patterns of DNA as well as the more obvious changes in cell or body structure that follow from the microscopic changes.
It was of course a big surprise for biologists to find that creatures can rearrange their own DNA in ways that can hardly be called accidental. In using antibiotic drugs to kill particular kinds of bacteria, as mentioned earlier, we often find that a species we attacked successfully has suddenly changed into a species that cannot be harmed by the drug. We say it has become resistant. But such new resistance implies genetic change -- the kind of genetic change we now know all bacteria to be capable of through their WorldWideWeb of DNA recombination -- the system that helped them cope billions of years ago with such life-threatening matters as ultraviolet radiation and poisonous oxygen in their environment.
Individuals in bacterial colonies change their DNA rapidly and effectively when the colonies are deprived of their usual foods and forced to live on what they were previously unable to digest, as Ben Jacob has shown. Even more impressive is the fact that larger, more complex creatures also can change their DNA in emergencies. Many insects and plants that we humans consider pests have made themselves resistant to our chemical poisons in just a few generations. Recent work in biology, such as that of Mae-Wan Ho, shows that instructions do not flow only one way from nuclear DNA to bodies, but that bodies can register changes in the environment and in themselves, communicating these changes to their DNA in ways that offspring may inherit.
Many other examples of intelligent and specific genetic change in response to circumstances outside organisms have been shown over the last half century. Just as we are finding that organisms are not separate from their environment, we are also finding that DNA is not separate from its environment within and without its organism. We know now that the DNA recombination capabilities of cells include the ability to reproduce DNA between cell divisions -- that genes can be copied and relocated when necessary. And this is only the beginning of our understanding of how organisms change their plans in order to survive in health.
The idea that the environment can trigger inheritable changes in creatures had actually been proposed before Darwin's opposing idea that environments can only select among changes produced independently of environments. Jean Lamarck, who named the study of living things biology, proposed it as the first modern theory of evolution. Lamarck's explanation of how living things changed themselves -- the classic example being giraffes stretching their necks to reach higher leaves and then passing on long necks to their offspring -- was not as convincing to Western scientists as Darwin's theory of accidental variety and natural selection through competition. Thus Lamarck's theory was ridiculed while Darwin's was adopted in the West, though Lamarck continued to be respected in Russia.
Neither Lamarck nor Darwin, of course, knew about DNA or even had a theory of genes, so they could not even guess that bacteria can trade around their genetic material or that larger multicelled creatures can rearrange their genetic material on the basis of experience in their environment. For that matter, many biologists still resist accepting the new evidence consistent with Lamarck's theory.
There is still a great deal to learn about biological information systems. Earlier we mentioned that the role of most nuclear DNA is still unknown and that it contains many extra copies of some genes. We guessed that the excess may be a hangover from the time when many bacteria contributed to the nuclear DNA. But it may also be, as some biologists believe, that all through evolution species collect and pass on reserve genes which may someday be useful in an emergency. After all, we keep libraries filled with books, the vast majority of which are unused at any given time.
It is certainly obvious by now that DNA can reorganize itself and repair the kind of accidental change that was thought to be the only way to evolution. It is a relief to know we are not just a lot of piled-up accidents and copying mistakes, but beings who have organized and evolved ourselves in harmony with the other living beings that form our environment. It is good to know that life is too intelligent to proceed by accident!
Environments simply are not fixed places that living things must fit into, adapt to, as we had thought, but the busy activity of living things themselves, working out their ways of life together as parts of the live Earth. This co-evolution in ecosystems now seems a matter of creatures changing themselves from the inside, in response to their environment, and also prodding changes in other creatures that are part of their environmental holon. A change in one species will thus be reflected by changes in some others. The Unity cycle reflects these `negotiations' in which living things evolve themselves and are evolved by one another, together evolving mature balanced ecosystems -- such as rainforests -- from immature ones with relatively few initially-competitive species. Note that each species is continually incorporating raw materials into its bodies, and being transformed in turn into raw materials for others, as Anaximander observed.
We only began studying ecology a few decades ago, when we recognized things going wrong in our environment because of changes we were making, especially after Rachel Carson called our attention to this enormous problem. We had been creating erosion and deserts by cutting down forests, poisoning land and sea creatures all over the planet with our pesticides and herbicides, polluting and destroying our air, water and soil with various chemicals, creating monocultures and warming the climate unnaturally.
Suddenly we began to study our planet's ecologically balanced body with attention to ecological `illnesses' and their possible cures, just as we had begun earlier to study our own bodies with attention to what went wrong with them -- to their illnesses. As Lovelock has pointed out, medicine began to make real progress only when we began studying the physiology of our bodies -- the way their interwoven systems work under normal, healthful conditions -- and so we will make more progress in understanding ecology and evolution as we learn how our planet's normal physiology works. How are its many kinds of supplies recycled? How do its information systems work to adjust imbalances? How do its countless and varied creatures contribute to its overall health?
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Much groundwork for planetary physiology can be found in the work of Vernadsky, the Russian biologist who described life as a disperse of rock, or rock rearranging itself, as we have been calling the same concept. Vernadsky pointed out that living organisms were originally built of the inorganic minerals of the Earth's crust and still contain such inorganic minerals, that they transform such inorganic minerals into living matter and living matter back into inorganic minerals. For this reason he saw no separation between biology and geology, but became interested in the constant transformation going on from the one domain to the other.
His concept of all living creatures together as living matter was used to propose that their part of the Earth's crust is energetic enough to actively transform the more passive parts -- what we have called the geological parts -- into itself and its products, literally feeding on it. On the surface, this concept of living matter is the same as Lovelock's concept of biota, as the sum total of living creatures, contrasted with their abiotic, or nonliving environment. But in Vernadsky's conception the emphasis is on geological continuity -- on each part as a transformation of the other -- whereas in Lovelock's conception the emphasis is on their interaction as separate parts of a working system. Oddly, Vernadsky, who apparently did not see the planet alive as a whole, perceived its integrity more fundamentally than Lovelock, who does see it as alive. Vernadsky was interested in the fact that the same atoms over time would alternate as part of animate and inanimate matter.
The processes by which organisms build up and destroy their own bodies -- their particular structures built of proteins, water, carbon compounds, and minerals -- is called metabolism, from the Greek word for change. Metabolism, which we touched on earlier in discussing the law of entropy, is a process of chemical changes in living matter by which energy is provided for taking in new matter, building and repairing cells, collecting and excreting wastes. Metabolism is divided into two parts: anabolism and catabolism, the buildup and breakdown of body substance, or protoplasm.
Metabolism, then, is the most basic autopoietic activity of all life. It recycles the materials of the Earth's crust into animate matter and then back into inanimate matter that can be used again to create more living matter. Vernadsky understood metabolism as the activity of all Earth's living matter taken together, as well as that of any particular organism, since he saw all living matter as a constantly shifting high-energy portion of the Earth's crust. We earlier observed that virtually all of the Earth's atmosphere, seas, soil, and rock are made from the products and dead bodies of organisms.
Even the hardest pure-carbon diamonds are pressed coal, which earlier was pressed animal and plant bodies. The sedimentary rock formed by pressure on the ocean floor, as another example, begins as sediment, including vast quantities of algae and animal shells, all passed through the guts of sand and mud-eating worms to further transform them, just as soil is transformed by the related Earth-eating Earthworms of dry land. Life, then, is the most powerful of geological transformers. That the record of Earthlife's evolution lies everywhere in geology, not only in recognized fossils, is referred to in the title of a book on Vernadsky's work, called Traces of Bygone Biospheres.
The geological activity of creatures also includes their production of atmospheric gases and their transfer of groundwater back into the atmosphere, a process that is clearly visible in the pumping action of rain forests, the rain then falling to dissolve more earth and rock. On the whole, however, the geological activity of creatures is less the larger they are, most of this work being done by microbes and rock- or mud- or earth-eating worms.
Some microorganisms contain half a million to a million times as much of some mineral, such as iron, manganese, or silver, as their environment does. The concentration of elements is another way in which life alters Earth's crust. Microorganisms are responsible for concentrating the radioactive materials, such as uranium, that we mine to produce atomic energy -- perhaps concentrating it in their habitats to keep themselves warm! Copper and other metals we mine have similar origins. From metal veins to continental shelves and the entire atmosphere, not to mention the composition of seas and soils, we see the staggering work of Earth's microbes.
It was so clear to Vernadsky that the activity of living matter was metabolic that he proposed we reclassify living organisms on the basis of their metabolism. He argued that our present classification from kingdom to species by way of phylum, class, order, family, and genus had led us to classify as related organisms many that really are not related under natural conditions. A better scheme, he felt, would be to divide kingdoms according to the way in which each of their species metabolizes supplies from its environment. The different ways in which organisms feed themselves had already been named by the German biologist Wilhelm Pfeffer. Vernadsky proposed them as a biological classification scheme.
In this scheme the metabolic process of organisms begins with the category called autotrophs -- self-feeding organisms that can build their own giant molecules, such as protein and nucleic acids, from simple molecules and elements such as minerals, water, and carbon dioxide. This category includes the photoautotrophs -- self-feeders that use sunlight in metabolizing basic molecules. A second major category of organisms is called heterotrophs -- meaning feeding off others, because its members cannot make large molecules from basic ones but must eat other organisms for their ready-made large molecules. A third category is called saprotrophs -- meaning to feed on the dead, because its members eat dead bodies and reduce their large molecules back to the basic ones the autotrophs can use. The fourth category is mixotrophs, which can metabolize in more than one way.
Finer distinctions within these categories are made as heterotrophs feed off other heterotrophs, and so on. What is important about this scheme is that organisms are classified not by their structures but by their functions within the whole geobiological life process. It recognizes organisms as self-organizing packets of the Earth's crust with enough energy to move about the more sluggish matter around them. Vernadsky even suggested that evolution may proceed by the natural selection of organisms which most increase biogenic, life-originated, energy -- the energy to move around the atoms and molecules of the Earth's crust at the highest speed.
The energy of living matter sometimes explodes almost beyond belief. A locust plague of a single day has been estimated to fill six thousand cubic kilometers of space and weigh forty-five million tons! It is the locusts' heterotrophic metabolism, of course, that makes them a plague as they suddenly convert vast quantities of the autotrophic crops planted by humans into their bodies. Most biogeologic activity goes on less dramatically, though it is impressive enough to consider that a single caterpillar may eat two hundred times its weight each day. All ecological areas have more autotrophs than heterotrophs -- it takes more of the former to sustain the latter. Thus, a forest may have 2,000 to 5,000 times as much autotrophic as heterotrophic living matter.
Vernadsky did not consider this classification scheme the only one possible; he recognized that one can learn much by trying other methods. One of his schemes was based on the type and amount of mineral content in organisms. Certainly he was one of the first modern scientists to see the Earth in a truly holistic way and to provide evidence of its evolution through the transformation of rock into living creatures and back into rock.
Many scientists have since built on his work or developed independent studies of the Earth from a holistic perspective, but Vernadsky's work has been given particular attention here because its fundamental conception of biogeochemical unity is so important and so little known in the West. Our best western scientific progress in understanding Gaian physiology has been through the work Lovelock, Margulis and their co-workers.