Living Systems in Evolution
copyright © 1999 by Elisabet Sahtouris
Shall we think of the young Earth at this point as a lifeless planet on which life is about to evolve? Most of us have been taught in school that animate matter is one thing -- it is alive -- and that inanimate matter is quite another, for it is not alive. Are the Earth's rocky crust and watery seas inanimate, lifeless matter while the plants and animals we know this story is leading up to are made of animate, or living, matter? Just what do we mean by the word life?
It may surprise you to learn that scientists do not agree on what life is. Some change their minds from time to time; others don't worry about the question "What is life?" believing the answer is known in some other science. In ancient Greece, when philosophers believed that all nature was alive, a physicist was someone who studied nature -- physis -- and so was concerned with living things. Later, when scientists decided to divide the world into animate and inanimate matter, physicists took on the job of describing how inanimate matter is put together, and biologists, whose name comes from bios -- way of life -- took on the job of describing living things.
Physicists think biologists know what life is because it is their job to know, but biologists keep changing their definition of life and they pass the question of how to tell life from non-life on to chemists, whose name comes from ancient roots having to do with the transformation of matter from one kind into another. So chemists divide chemistry up, in their turn, into two kinds: organic chemistry, the study of living matter, and inorganic chemistry, the study of nonliving matter. Chemists know something about the transformation of inorganic matter into organic matter, but the question of just when and where life began on our planet still gets tossed back and forth among them, or taken back to ideas from physics.
Some scientists talk about life in terms of non-equilibrium thermodynamics. This contrasts it with the equilibrium dynamics of nonliving things -- the physicists' way of solving the problem they created long ago when they declared that life was separate from non-life. Whether or not physics is the appropriate branch of science to define life, this new view at least talks about life as a process rather than as a kind of matter, and that seems closer to what life is all about.
Before religion and science parted company, the answer to the question of how life began was easy. Scientists themselves believed that God created living things, such as plants and animals and people, putting them into the nonliving world he had created for them. But later, when scientists tried to explain the world without bringing God into the picture, they were stuck with believing that life is a special kind of matter that somehow comes from lifeless matter. One version of this belief was known as spontaneous generation -- the belief that worms, for example, sprang from bits of dead garbage or rotting meat.
Louis Pasteur put an end to that, as we are also taught in school. Or did he? His very careful experiments showed that worms come only from eggs, and never directly from garbage. But where did eggs, which are living things, come from? Flies or other insects, also living things. The explanation seemed easy with a theory of evolution: they came from other worms, which had evolved from the smaller, simpler creatures we traced all the way back to microbes -- living things so small they can be seen only through microscopes.
But where do microbes come from? That is still difficult to tell, but we assume they come from the simplest molecular systems that could maintain and reproduce themselves. Some biologists believe that life began with small clumps or sacs of organic molecules. The organic molecules themselves are considered nonliving matter that comes alive when they get stuck together in certain ways that permit them to act on each other to form a living system. In other words, scientists still believe that life comes from lifeless matter. In this sense, spontaneous generation was not so much disproved as pushed down to things much smaller than dead meat and worms.
We are still stuck with the question of just what life is. What is it that brings the lifeless molecules in some places, on some planets, to life when they are chained and clumped together in certain ways? Even though we are talking about very tiny things, there is still a big jump from nonliving matter to life.
We have already suggested that it might be better to see life as a process than as a kind of matter. Perhaps it would also help if scientists did not keep looking for the answer only in tinier and tinier parts of nature, believing that in doing so they would see just how things are built from the bottom up.
If we begin, instead, by thinking of wholes, or holons, that form their own parts from the top down, so to speak, everything looks very different. Think, for example, of the huge protogalactic cloud holons we talked about in Chapter 2. If we could watch a movie of the evolution of a protogalaxy sped up so that billions of years happened in a few minutes, what would we see? We would see it whirl and throb, grow and change, its parts dissolving and exploding, more complicated new parts forming in their place and even reproducing themselves as the mature galaxy took on its complicated form. Galaxies themselves split apart and merge with others on collision. And within galaxies -- perhaps within all of them -- some planets produce what we all agree, here on Earth, to be life.
While astronomers may speak of the lives of stars, they do not seriously count stars or galaxies as living beings. Yet galaxies do some of the things by which we all recognize living beings in our everyday experience of Earth, such as keeping their form through many changes within them, creating and replacing their own parts, sometimes even growing and/or dividing to form offspring galaxies.
The most promising definition of life among biologists, in fact, seems very nearly to fit galaxies, if not stars. This is the definition of life we owe to the Chilean biologists Humberto Maturana and Francisco Varela. Their concept of life is a process called autopoiesis (pronounced auto-po-EE-sis), which in Greek means self-creation or self-production.
An autopoietic unity, or holon, produces the very parts of which it is made and keeps them in working order by constant renewal. An autopoietic holon works by its own rules and creates a boundary that distinguishes it from its environment and through which it exchanges materials with its environment. We do not see such boundaries around galaxies, yet galaxies are visible as distinct entities that maintain their shape while producing and reproducing their parts. The Earth, as we will see, also produces and renews its parts, including the thick atmospheric boundary through which it exchanges radiation energy with its environment.
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It seems that as we learn more about our universe, we need to change our scope and the questions we ask about life. Until now we have assumed that all the universe is nonliving matter except for some matter on planets such as ours. But why should we divide the universe up in this way? Physicists now tell us, as we will discuss further in the last chapter, that the matter-energy of the earliest universe was already, by its very nature, bound to form living systems. Had things been just the tiniest bit different at the beginning, this would not be so and we could not have evolved. Perhaps, then, life evolves as the essential process of the cosmos as a whole and is not just something happening at a special point we hunt for in vain.
This is, in fact, becoming an increasingly acceptable hypothesis among physicists who have revived the ancient Greek concept of the source potential, or plenum, as a zero-point energy field (ZPF) -- the infinite energies existing at every point in spacetime and from which source all matter is created. And even beyond that, ever since quantum theory proved so powerful, some physicists have proposed consciousness -- a basic universal consciousness -- as the source of all creation.
Historically, we see that science took a big step away from religious explanations of the world, and that it is now taking another big step toward a merger with spiritual explanations. The first step involved a shift from seeing the universe as created by an outside intelligence called God, to seeing it as happening solely through the purposeless mechanics of evolved forces and parts. The second step is a shift from mechanical to organic models of nature, with its organics as self-creation process, not blind mechanics. If science `officially' acknowledges cosmic consciousness to be the continually self-creative source of the material universe, as many individual scientists now do, this step toward an integrated spirit-energy-matter worldview will be completed, while older worldviews, both religious and scientific will fade into history.
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Galaxies are surely a very significant part of cosmic life processes. It certainly seems that our Earth, born from our galaxy, is alive in its own right.
We do not know whether in our own solar system planets such as Mars and Venus began coming to life and then failed to evolve because they could not keep themselves alive. It is ever clearer that, as with the seeds and eggs of plants and animals, far more planets are produced than actually come to life. Planets must have just the right composition and be in just the right relationship to their star to come as alive as has our Earth. Yet even if only a few planets among many succeed in coming to life, there must be billions of living planets in the universe. And the others -- the majority of planets that do not come alive in their own right -- may still play a supporting role in the life of their galaxies.
The creatures we are used to thinking of as alive, such as plants and animals, contain much supporting `nonliving' matter in their woody trunks and shells and bones, their thorns and hooves and nails, their hair and scales. Nonliving planets may also be very much a part of live galaxies, perhaps even playing important structural roles in their dynamics.. What about the Earth itself? Many scientists argue that it cannot be a living being because only its outermost layer -- thin as the dewy mist on an apple at dawn -- shows signs of life. What, then, we may ask, about a redwood tree, which is ninety-nine percent deadwood with just a thin skin of life on its surface? No one argues that redwoods are not alive.
It is new in modern science to look at the cosmos and the nature of our planet in this way. It is not easy for scientists to jump from seeing the Earth as a nonliving planet that became a home for living creatures, to seeing it as a single living being with its creatures as much a part of it as cells are a part of our bodies. The scientific studies of Earth have been divided, as we said, into studies of living and nonliving matter. Geologists have had the task of explaining how the geological `mechanisms' of nonliving matter, such as rock, change with time and weathering. Their work was not intended to be mixed up with that of the biologists who study living things, since these living things have been and still are believed by most scientists to arise in ready-made geological environments and either adapt to them or die out.
Now, however, the jobs of geologists and biologists are getting mixed up whether they like it or not, for the same stardust that was transformed into a rocky planet continues to be transformed into living creatures. What we are made of was stardust long ago, transforming itself into rocky Earth crust and, after a long transformative history of evolution, into us.
To make things more complicated, much of the rock that is transformed into live creatures is later transformed back into rock. And so, just as creatures are made of atoms that were once part of rock, almost all rocks on the Earth's surface are made of atoms that were once part of creatures -- creatures that built themselves from the atoms of still earlier rocks.
Think about that. The recycling of stardust gets to be a complicated matter as a planet comes to life. Geologists are now just beginning to believe the Russian scientist V. I. Vernadsky, about whom we will say more later, who understood life on Earth as "a disperse of rock" -- rock rearranging itself over billions of years; rearranging itself into ever more complicated forms of life from microbes to men.
That alone is enough to mix up geology and biology, but there is even more to it. Our planet never was a ready-made home, or habitat, in which living creatures developed and to which they adapted themselves. For not only does rock rearrange itself into living creatures and back, but living creatures also rearrange rock into habitats -- into places comfortable enough for them to live in and multiply.
But let's take it one step at a time and look first at life as rock rearranging itself. How can this happen?
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We begin to see that there is more than one way to understand what life is. We just saw it as a mixture of geology and biology. Let's now try looking at it as a mixture of physics and chemistry.
Remember the forces, such as gravitation, that helped create patterns in the cosmic dance of particles and atoms? One of those forces is the electric force that holds atoms together. This force keeps the outer particle dancers of atoms, their electrons, from flying off into space away from their nucleus of heavier particles. This is not entirely unlike the way gravitation keeps planets from flying off into space away from the Sun, though the orbiting electrons are not hard balls like the ones on the old-fashioned atom models that looked like miniature solar systems.
Powerful electrical, or magnetic, fields were set up by the interaction, through the Earth's crust, of the Sun's energy and the molten metal of Earth's core. We might compare this with a giant battery whose energy can be used to do all sorts of work. At the microcosmic level, the electric force allows electrons to dance in two atoms at once, thus holding the atoms together as a molecule. The more atoms that dance together in this way, the larger the molecules formed.
The strong energy of Sunlight coming to the Earth's crust through the thin early atmosphere stirred up the molecular electric force within the great electric fields, creating storms above and breaking up molecules in rock dust, mud, and seawater near deep ocean rifts below, re-forming them into new and larger molecules. When molecules break up and recombine in new patterns, we call it a chemical reaction, since chemistry is the study of such transformations in the patterns of molecules. The energy that stirred up the electrical force recombined many molecules of the Earth's crust.
Such chemical reactions also happen elsewhere in our galaxy. The larger organic molecules such as those of sugars, acids, and lipids (fats) that were formed on the young Earth are also formed in large quantities and great variety somewhere in the center of our galaxy and perhaps all over it. Some of them come to Earth by way of meteors. It is even possible that those planet `eggs' which come to life may be fertilized by meteors.
Some chemical transformations, as we said, were due to electrical storms created among clouds of cooled steam in the early atmosphere as the Sun's energy heated Earth's surface. Besides helping large molecules to form, these storms drove a water recycling system, collapsing clouds into rain, which fell on land and sea, the water rising again by evaporation and collecting back into clouds.
Rainwater ran over the rocks, creating grooves that over the eons formed riverbeds and valleys, carrying ground sand and dust full of rock salts to the seas. Rivers and streams thus formed as the bloodstream of our embryo planet, carrying the supplies needed to develop or evolve its life. For a live planet needs not only a great deal of energy but also flowing matter such as atmospheric gases and water to move things about. As we will see, planetary life is not something that happens here and there on a planet -- it happens to the planet as a whole.
The largest new molecules probably formed in shallow waters with the help of Sunlight and lightning storms, or perhaps with the help of the Earth's internal energy around cracks in the Earth's crust on the sea floor. Even the Sun's drying heat at the water's edge may have played a role in forming large molecules and packaging them.
Large molecules, such as naturally forming sugars and acids, absorbed a lot of electrical energy, which was then useful in speeding up their chemical reactions to form ever larger molecules -- giant molecules built from the simpler sugars and acids. Some scientists believe the giant molecules formed as large molecules lined themselves up on molds or templates of clay or other crystal matter that had regular, repeating surface patterns or notches for the molecules to hold on to. Others believe that the production of giant molecules happened only after the earliest molecular life systems were already organized within tiny capsules.
Earthlife may be described as autopoietic-self-creating-holons forming within the great Earth holon. In all its creatures, from its earliest microbes to later organisms, we find carbon, or rather reduced carbon compounds, which are carbon atoms surrounded by hydrogen atoms, playing essential roles. The lively energized carbon of the Earth combined easily with oxygen, nitrogen, sulfur, and phosphorus to form all sorts of organic molecules and substances. In fact, you are made of very little other than these six elements in their rich variety of combinations.
Among the giant molecules formed from smaller ones were proteins -- long strings of amino acids, which are themselves molecules made of various combinations of a dozen or fewer carbon, nitrogen, hydrogen, and oxygen atoms. Other giant molecules, assembling from both acids and sugars, were those we call ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). DNA may actually have been a later development of early living systems based on RNA. Whatever the exact sequence, DNA and RNA came to work together with proteins as the copying and building system of life.
DNA molecules are long chains of smaller molecules joined into long, twisted zippers. We have discovered that the teeth of these DNA-molecule zippers act as a four-letter code that can be arranged in endlessly different patterns, just as letters of the alphabet can be written into words and sentences and books. Because of this, a DNA molecule can hold information. After all, information is really anything in formation -- anything that is in an ordered pattern rather than in chaos. Some scientists argue that whatever is in formation becomes information only when used by a living system; in this book we define information as anything that is in formation. A book, for example, contains information even if no one reads it, as does a solar system even if no one uses it.
Information, if it can be copied, can be a plan -- a plan for a new copy, or a code plan for something else. DNA can copy, or replicate, itself, but not without the help of proteins that can unlock DNA zippers. Once unlocked, the DNA unzips itself into two half-zippers. As these float around in a soup of smaller molecules, the teeth of each half -- all letters of the DNA code -- attract new partners just like those that were opposite them in the closed zipper, because those are the only ones that fit into place.
Presto! We have two zippers where there was one, and the two are exactly alike if no mistakes have been made. The DNA-protein partnership evolved in such a way that while proteins unlocked DNA zippers, they also got DNA to store plans coded for building more protein as well as more of itself. Thus the DNA-protein partnerships as wholes were capable of reproducing themselves.
This is a bit oversimplified, since viruses, our only examples of RNA or DNA coated by protein alone, have to get inside cells where other things are available in order to reproduce. Nevertheless, protein with DNA or RNA, or both DNA and RNA, formed molecular cooperatives that became the basic reproduction system of carbon-based life. This genetic system -- DNA is composed of sequences we call genes (from the same root as genesis) -- is usually described as one-way, the DNA code strictly determining the production of proteins, which are the main building materials of living holons within the Earth holarchy. But recent evidence indicates that proteins can in turn affect and change the DNA code. We will get back to this form of cooperation in later chapters.
Less than five percent of DNA is composed of the genes which are blueprints for the specific proteins of which living creatures are composed. The role of the remaining more than ninety-five percent is still largely a mystery. It is as though we know just what kind of bricks or stones, wood, glass, etc. are used in building an elaborate building, but still do not know how to read the architectural blueprint.
At some point early in the Earth's history there were plenty of the sugar and acid molecules that were needed to build the long chain molecules of RNA, DNA, and protein. And so the formation of these cooperative partnerships very likely became inevitable in the Earth's warm wet mud and shallow seawater where molecules could move about freely and bump into one another. Possibly there was a long time when these partnerships could hardly have been told apart from the thick soup of building materials around them.
Some scientists, however, argue that such partnerships really could not have gotten under way until the molecules were enclosed in sacs, or membranes, that held them together with other supply molecules and protected them from being dissolved. The most likely candidates for such sacs are called liposomes, literally meaning fat bodies. Liposomes, so tiny they can be seen only with an electron microscope, form as hollow spheres of lipid-fat-molecules, something like microscopic soap bubbles, whenever lipid molecules find themselves in water. This is because the tails of these lipid molecules are hydrophobic, or water avoiding, swinging quickly away from water, protecting one another from it by turning inward so that their heads form a tight sphere around them. Sometimes a double-layered sphere forms with water inside and outside, the double layer having all the lipid molecule heads on both surfaces, with all tails between the two layers of heads. This is the typical formation of simple cell walls and persists even in the most complex cells today.
If a soup containing liposomes and a variety of large molecules is repeatedly dried out and liquefied again, the liposomes break open and flatten out during dry times and re-form their spheres in wet times, sometimes around large molecules -- even as large as DNA and protein molecules -- that may become trapped inside them while they are broken open. Such conditions must often have occurred at the edges of early seas. The liposomes themselves then function as a skin, or membrane, which serves the molecules inside it both as a protection from, and as a connection to, the outside world. The membrane permits selective chemical crossings, allowing some kinds of atoms or molecules to come in and other kinds to pass outward through them. This soon makes the inside environment chemically different from that outside. Such an arrangement fosters the development of chemical cycles that are basic to living cells.
However the first cells formed, protein became the main material of which living creatures built themselves, while RNA and DNA stored the plans and made it possible for living things to multiply. Some protein molecules came to play a particularly important role by speeding up what other molecules did -- say, by speeding up the chemical reactions that build new protein or copy DNA. We call these special proteins enzymes, and their wonderful talent for speeding up the chemical dance is very important to our planet's life. In fact, the presence of enzymes has been suggested as one way of defining the presence of life, and the first enzymes likely occurred as a widespread chemical Earth event, perhaps both outside and inside early cells.
While details are still missing, this is essentially how the solid and molten crust of the Earth began to rearrange itself into living creatures. Some of its material gassed off into atmosphere, part reformed into seas, some broke up and was washed into the seas. With the help of great amounts of energy, larger molecules formed and joined into partnerships, set up chemical cycles in early liposomes, speeded up their own reactions with enzyme activity, reproduced themselves, and through all this established themselves as living, or autopoietic, holons -- the earliest creatures in their own right. These creatures dwelt within the larger living holon that had given them life and to which they gave a new kind of life in turn. Thus on the one hand we can say that tiny separate living holons evolved all over the Earth, but on the other hand we can say that the Earth holon was coming ever more alive as it evolved its own autopoiesis through a new kind of self-packaging chemical activity.
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From our old point of view we could see the beginnings of life only as a collection of microbes descending from some primeval cell that formed accidentally somewhere on Earth, giving rise to offspring that were forced to adjust or adapt their way of life to it by natural selection, which we will discuss in Chapter 7. This was a logical way to see things when we formed our concept of life from our study of individual creatures small enough for us to see as wholes. In our new way of seeing life as autopoietic systems that may be as large as the Earth or even larger, we can think of Earthlife as a planetary process -- as the chemical reactions of the planet's crust speeding up, transforming the crustal matter into a blanket of masses of microbes, which in turn transform more of the crust into their livable home, as we will see in the next chapter. And while all this happens at the microcosmic level, the macrocosmic events of the largely molten, still radioactive planet keep its crust heaving, cracking, and sliding, pushing up mountains, buckling in valleys, changing the shapes and positions of continents amid its deepening seas. All together, this is the self-creating dance of a living planet driven by its Sun and by its own energy.
One way of looking at all this is to see the Earth as having come alive through all sorts of `border activity.' The crust that stirred to life was the boundary enclosing the Earth and at the same time connecting it to outside energy from the Sun and to new materials coming in as meteors. Then, the first cells seem to have formed specifically at the boundaries separating and connecting the land and the sea, or separating and connecting the inner magma with the crustal surface at volcanic sea floor vents. These cells' own boundaries made their individual lives possible by separating them from and connecting them to their environment. At all levels from great to small, this border activity can be seen as highly creative and cooperative -- a lesson we humans, with the boundaries we have created among ourselves, might well take to heart.
Let's stop to imagine that we are watching a fast-running movie of the early Earth as it evolves within the larger being of our Milky Way galaxy. As we approach the Earth, we see it whirling and heaving, its thin crust rising and falling, breaking and slipping, bleeding lava where it tears open and sighing bursts of steam. Meteors and planetoids, which are part of the supernova's debris, strike and wound the Earth, making great splashes of molten rock and gas. The thin atmosphere is often reddish with smog produced by the reactions of its own gases. Lightning flashes, and seas form during heavy rains until masses of land and sea become distinct, though the seas are brownish beneath the murky atmosphere.
Slowly the crust thickens and cracks into plates that slide slowly over the surface, carrying the land masses into new patterns. Patches of colored microbes appear and grow along the shores; gradually a tougher but clearer atmospheric skin develops, making the seas turn a sparkling blue. Meteor impact is low; turmoil subsides, and much of the land becomes covered in green. Now and then ice moves down over the green before withdrawing again to the poles, raising and lowering the level of the seas, covering and uncovering the land as though the whole planet is breathing in some gargantuan rhythm. Everything is in constant motion as the Earth shimmers and glows in the Sun against the darkness of space, its changing cloud patterns swirling over blue seas and varicolored lands.
These changes actually happened over billions of years, at a rate too slow for us to recognize as very active. Yet a billion years to our planet is less than a decade is to us. When we use our imagination to see these changes within the time span of a short film, the truly amazing thing is that our planet looks very much like a living creature -- perhaps the great cell that popular science writer Lewis Thomas saw it as.
Our movie makes the young planet appear to be trying hard to express itself in a new way as its materials churn about, its crust forms and reforms, its seas and clouds pool over the rocky crust. It has enormous energy of its own and receives more energy from the Sun, which sends it light and heat. It might remind you of a chrysalis transforming a caterpillar into a butterfly, or of a chick embryo turning and growing inside its shell.
Already at this early stage the Earth begins to fit the autopoietic definition of life as it is creating its own parts, including the tiny autopoietic microbes which, as we will see in the next chapter, create the thickening atmosphere that becomes a new boundary membrane or skin. In later chapters we shall see more evidence of autopoiesis as new complex holons form within the planet's holarchy.
Had our movie shown the other planets as well, we would have seen the sharp contrast as they settled into relatively stable patterns, the solid ones dull in color, while Earth's metabolic activity brought it to life with radiant blue and green colors beneath its swirling breath of white cloud.