Living Systems in Evolution
copyright © 1999 by Elisabet Sahtouris
We are still not sure why warm-blooded animals dream during sleep. Sleeping and dreaming are special behaviors that evolved in mammals and were passed on to their descendants, yet no one really knows why. Scientists used to think sleep restored worn bodies, but there is no good evidence for this theory. Some people sleep very little, even never, and have no problems as a result. For most of us, however, sleep is clearly an unavoidable aspect of our physiologies. That makes it highly likely that sleeping and dreaming evolved because somehow they did our ancestors some good.
One guess is that sleeping was a way to keep warm-blooded bodies, which worked just as well by night as by day, quiet and in hiding during the hours when dinosaurs hunted, as mentioned above. Perhaps dream images of dinosaurs kept the mammals just close enough to waking so they could get up and run fast if a dinosaur poked its head into the nest. This theory seems to fit mammals that are active by night. But shrews, small mouse-like mammals, are active day and night, while bats, which are small mouse-like mammals with big wings, sleep almost the whole day and night. Many mammal species, including humans, do their sleeping at night instead of by day.
Another theory says that we are put to sleep by a chemical that daylight builds up in our bodies, making us more and more tired by nightfall. That still does not explain what good sleep and dreaming did us. All we know for sure is that they were among the many new kinds of behavior organized in the larger, more complicated brains of early mammals such as the possums. Perhaps we sleep simply to prolong our lives, for sleep does slow down body activity and thus makes a body last longer. Bats live about five times as long as their super-active shrew cousins with the same body size, though both species have about the same number of heartbeats per lifetime! But long life in individuals does not necessarily mean their species survives longer, as it is clear that bat and shrew species have survived equally well.
Possums, besides being warm-blooded, hunting by night, and sleeping with dreams by day, take care of their young. Caring for babies through an extended nursing period became the basis for more complex social behavior. Bigger brains had room for more complicated ways of seeing, feeling, and doing, of understanding and acting. Among the new ways of seeing and feeling was the ability of parent animals to recognize their babies and feel the need to care for them -- to feed them, clean them, protect them, and teach them, as both birds and mammals do.
Again we must note that nature does not keep things in neat human categories, and so we find insects, such as wasps, providing for their young in advance of their hatching by storing food, and frogs that keep live young in their stomachs, regurgitating them now and then to see if they are ready to function on their own. Some species of fish have evolved quite elaborate care of live young by their parents, though they are not warm-blooded. Seahorse daddies keep babies in kangaroo-like pockets, and some daddy cichlid fishes keep hatched babies in their mouths. After they learn to swim on their own, the fathers herd them and let them back into their mouths any time danger threatens.
Still, if you could watch and compare a fish father and a cat mother caring for their young, you would quickly see that the fish has simpler movements and acts more automatically, while the cat often seems to have a choice about what to do next. The tendency toward particular patterns of behavior evolved in animals together with the structure of their bodies. Such innate, or built-in, behaviors -- say, nest building or courting rituals -- are popularly called `instinctive,' though most scientists, having dropped the old concept of instincts, call them `species-specific behaviors' or simply `innate behaviors.' Whatever we call them, the animal performs them without having learned them in the way we understand learning, and so they appear automatic, performed without choice or flexibility. Sometimes they are therefore called `fixed action patterns.'
As evolution transforms creatures from simple animals to amphibians, to reptiles, and then to mammals, we find nervous systems getting more complex and behavior becoming more flexible. As brains grow larger and more complicated, some of the innate behaviors loosen up, giving the animal more freedom of choice in responding to its environment and to its own inner urges. The brain is increasingly a flexible coordinating system for changing behavior to fit changing circumstances.
As animals gained more freedom in what to do, and how and when to do it, they gained more freedom in acting on feelings as well as information and in learning new behaviors. Mammals clearly began to show what we recognize as feelings, and some of these feelings seem to be the beginning of evident love in animal evolution. Animal mothers apparently felt good staying close to their babies, feeding them on milk from their own bodies, licking them clean, and hiding them from danger. Whenever mothers and babies got separated, both felt distress and cried. They got back together by listening to each other and tracking the cries. That was the beginning of the voice communications we humans have evolved into complex languages that can be used to express extremely complex ideas and information. Birdsong is a more innate pattern of voice communication, though baby birds often have to learn the exact pattern for their species from the adults. Whales and dolphins have reasonably complex languages they teach their young.
One of the most important things mammals learned and taught one another was to play. Play in baby animals seems to be practice for more serious grown-up behavior such as hunting or winning a mate. You can see wide varieties of baby mammal play, from kid goats butting one another to puppies hiding from and pouncing on one another. Mother cats clearly show their kittens how to practice hunting on one another without being too rough, and the kittens come to enjoy the activity. Ever since it evolved, play has been an important part of social life -- the life of animals living together, making a living together, communicating, and caring for one another.
Mammals such as cats, dogs, and monkeys have flexible bodies that make it easy for them to care for babies and to tumble about in play. Flexible feet with toes and nails, or claws, can become very useful paws with which an animal can do many things, as we see watching raccoons manipulate food in complex ways. Stiff-legged mammals without flexible toes, such as goats, antelope, and horses, are specialized for climbing and running, but not for tussling or washing their food! Thus they lead simpler lives, grazing rather than hunting other animals, running from their predators, shielding their babies as best they can. While their strong, slender legs and hooves make them surefooted runners, such legs are too specialized for baby care and play, so their young stand and run on their own stiff legs early.
Mammals of all shapes and sizes -- some very specialized, some more flexible -- branched off from early possum-like ancestors. Each new species created new steps in the Gaian dance of life as it wove itself into a complex environment. While the oceans filled with animals from microbial plankton to sea snails, from fishes to mammalian whales and sea lions, forests grew thick with colorful insects, birds; and furry mammals, plains rang with the clattering of fleet-footed hooves or shook with the heavy tread of pachyderms.
With the dinosaurs gone, mammals were the largest of land animals, just as trees were the largest plants. All through evolution, larger and larger individuals had evolved in both the plant world and the animal world. But there was a size limit beyond which individuals did not work so well. Trees that grew too tall could not stand upright in storms or pump water to their highest leaves. Giant dinosaurs were too large to survive a catastrophe that smaller creatures did survive. Mammals the size of whales and elephants seem to be about as big as the Gaian life system can manage successfully. Larger bodies, among other problems, would have trouble getting enough food and oxygen. An animal ten times as big as another in each direction weighs a thousand times as much and needs a thousand times as much food. The large animals that have evolved are very few in number compared with smaller species, down to the most numerous of all, the endlessly hardworking bacteria.
While some Gaian animals reached size limits, there seemed to be no limits to variety in their body designs and behaviors. They evolved countless wonderful ways of swimming, slithering, crawling, running, climbing, and flying; of hunting, fighting, playing, and learning. They had senses to see, hear, smell, feel, and otherwise perceive their world. They communicated with one another and found endless ways of making homes and feeding themselves, often developing complex social interactions. They developed marvelous furred and feathered body designs, many with striking colors and seductive dances to attract their mates.
Where could Gaian creation go next? What was possible that had not already been developed?
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Think about the world as it was with this tremendous variety of monera, protists, funguses, plants, and animals woven into and weaving the patterns of life. Rock had transformed itself into countless creatures, which had created a rich atmosphere, nourishing seas and soils, producing vast sea and land ecosystems for themselves. Every species of Gaian creation had its part in the dance. Their co-evolution contributed enormously to the overall evolution of their entire planet body.
This great Earth being knew itself in the same sense that we have talked about our bodies knowing themselves. It had and still has the body wisdom to take care of itself and to keep on evolving. In particular, it had learned a great deal through so many generations of creatures living out their lives in concert -- in cycles of individuation, conflict and negotiations to new cooperative arrangements. All this went on without those creatures thinking about their lives or relationships with one another any more than do our own cells and organs ponder the meaning of their lives.
Like the cells in our own bodies, they played their parts well. Their perceptions and communications were good enough so that even if they suffered from conflicts and had to learn to resolve them through all sorts of trial and error, the one thing they did not suffer was confusion. In a way, they were like actors who played their parts very well even when improvising -- actors who said their lines appropriately. But could they have imagined what the whole play was about in the ways we try to figure it out?
This seems to be where the next step in the dance came in -- with the evolution of a very complex and flexible big brain, in a flexible body with a variety of sensing devices, dextrous hands including opposing thumbs, and a throat with vocal-chords uniquely suited to speech between lungs and mouth. This would be a brain capable of finding external ways to communicate with other such brains through language far more complex in expression than body gestures, grunts, roars and whistles could achieve. Through the social use of language, the new big-brained creatures were to become more overtly aware of themselves and one another and of the play they were part of -- to wonder about it and about their roles within it.
The biggest-brained mammals in the sea were the whales and dolphins. And what successful creatures they were! Their bodies had evolved in perfect harmony with the sea to which they had long ago returned. They could roam the watery three-fourths of Earth's surface, seeing by sonar when the water was murky and with their eyes when it was clear. They could adjust to the coldest and warmest, the deepest and shallowest waters, and they could devise a language in which to talk and sing to one another from one side of an ocean to the other.
It is quite possible that cetaceans -- whales and dolphins -- have evolved the ability to think about their world and to share their thoughts with each other. Dolphin language, for example, is very complex and apparently very much faster than ours. We have just begun seriously to study it, and so far we have made little progress in understanding it. We have even less understanding, or even comprehension, of what their telepathic communications may be like. All we do know is that if brain size and anatomical complexity are clues to intelligence, they outstrip us.
Until very recently we humans believed ourselves to be the only intelligent creatures, and we didn't treat other creatures with much respect. In fact, we have come close to killing off the whales and dolphins just as, earlier in our history, we apparently killed off most species of elephants -- the only other land mammals with brains bigger than our own. Homo sapiens may even have killed off other species of early humans while competing with them for food. The last other known human species was Neanderthal, who disappeared from the evolutionary record only about forty thousand years ago. Some scientists think they may have disappeared through interbreeding with our own species; others think we killed them off.
In any case, cetaceans had little to worry about until our own human species evolved brains as big and clever as their own, thirty million or more years after theirs had evolved. Though we humans evolved so much later than cetaceans, by Gaian standards we evolved with incredible speed, our brains blossoming suddenly, expanding in size almost explosively from the much smaller brains of our apelike ancestors.
Stories abound about our human origins, from the better known religious stories to no few scenarios in which we result from interbreeding between extra-terrestrials and apelike Earth creatures, or from the takeover of the apelike creatures' bodies by more evolved non-physical beings. While we have, at least as yet, no clear confirmation of any such stories, we would do well to recognize that the purely Earth-evolutionary story of human evolution still contains plenty of gaps and mysteries. With those limitations in mind, let us continue the story as scientists have pieced it together.
To become human, those ancestral apes would have to do something similar to what their much more ancient polyp ancestors did. They would have to practice neoteny -- that is, they would have to remain childlike by not growing up into mature apes at all!
Piecing our own history together from fossils and other biological evidence, we get a story of human evolution goes something like this: Generation after generation, some baby apes were born prematurely, until at birth the bones on the tops of their heads were still soft and not grown together. This permitted their brains to grow much larger after being born through the limited diameter of their mothers' pelvic bone door to the world.
In the first year of a human baby's life its brain grows three times bigger than at birth, quickly passing the size of a grown-up chimpanzee or gorilla brain. But human faces keep a babyish flatness instead of developing grown-up snouts and jaws and bony eye ridges. If you look at chimpanzee families, you will easily see that people, even grown-up people, look much more like baby chimps than like adult chimps.
Scientists have shown that our DNA is 99 percent identical with that of chimpanzees, and have estimated that we branched off from common ancestors only two or three million years ago. Some scientists find it difficult to believe our species can be so different from our large ape relatives with so little difference in genes, but perhaps the major changes in our bodies have been due simply to a few genes that regulate maturation. The potential for greater size and complexity in ape brains may be there, but locked up by the early sealing of their skull bones.
However humans came about, it is clear that genetically we are very closely related to our much more peaceable chimp and gorilla cousins, and this may help us overcome the obsessive idea that we are naturally violent creatures. On the other hand, eager to see our own violence as natural -- and at the same time to see ourselves as better than our ancestors -- we emphasize the occasional violence we do find among great apes, as well as among pre-modern peoples.
Our obsession with violence is worth a brief digression. We teach history as the history of warfare, naming its great ages after metals from which human males made weapons. We teach history, rather than herstory, though half of humans are female. Schoolchildren, asked to tell what they know about Incas and Aztecs, are far more likely to remember warfare and human sacrifice than their phenomenal agricultural sciences and architecture, their metallic arts and weavings -- as if such great economic and artistic cultures could have been built on mayhem and murder. Of course we do not teach children that European culture at the same time was built primarily on the massive human sacrifice of the Inquisition, which was also Europe's chief export to the Incas and Aztecs, in turn for their gold and silver, which financed Europe's industrial revolution.
All this to say that questions of violence are truly of huge importance for humanity, but social bias in discussing them clouds the real issues. Violence is not `good if ours and bad if theirs' -- it is a danger to all. The really important issue is that we endanger ourselves as a species by believing we cannot evolve from the violence we do to each other and to other species -- the competitive belligerence from which we must evolve to peaceful cooperation as so many other Gaian species have done.
Back to our story, the babyish new apes, without big snouts in the way, could easily see what they were doing with their hands, which had long been good at grabbing and holding on to things. After all, they had been living a life of swinging through trees for millions of years. Now, more and more, perhaps for lack of adequate food, these evolving creatures foraged and made their homes on the ground instead of up in the trees. Their arms and hands, no longer so engaged in swinging, were free to do new things. In time, their opposing thumbs grew increasingly dextrous at holding and making things. Meanwhile, their necks and hipbones, legs and feet, were gradually re-patterned for walking and running upright.
The longer these new upright mammals stayed babyish, the later their teeth came out and the less hair they grew, though they may also have lost hair in evolving a cooling system that let sweat out all over their bodies. This cooling system helped them run for such a long time that the animals they learned to chase for food and clothing tired out before they did.
Young humans needed warmth, protection, and affection. They needed to be taken care of much longer than other young mammals. But their long childhood gave them time to play and be curious and learn new things, and parents had plenty of time to teach their children before they grew up. In fact, it is because we never really grow up the way apes do that we can keep on playing and learning new things all our lives -- providing we don't seal our own brains up with fixed ideas as inflexible as the old innate behavior patterns.
There were endless new challenges for these first humans. Without the warm coats, strong claws, and long teeth that other animals their size had, they had to survive by using their big brains, their clever hands, and their ability to run longer, if not faster, than many other animals. But perhaps this was in their favor, for even today the most creative and successful people are often those who didn't have everything they wanted early in life and had to work hard to overcome disadvantages.
Early human diets included a wide variety of leaves, roots, seeds, nuts, fruits, eggs, grubs and easily caught small animals, including fish and shellfish. Nets and snares for birds, fish and rodents were probably the primary hunting and gathering tools for a long time. But our ancestors also learned to drive successful predators away from their game catches and acquired a taste for hunting such game themselves. No doubt this made them more inventive. Tools and weapons extended the use of their hands; keeping warm by turning the larger animal skins into warm clothing for themselves was as important as eating their meat.
We can be quite sure that that early humans were both cooperative and scrappy, with emotions from avarice to anger, from lust to laughter, from fun to fear, playing important roles in determining their behavior. Families and groups of families shared caves and other shelters as well as their ways of life, living together where food was plentiful, traveling together when food got scarce. As they became ever more social and communicative, we can imagine them laughing and dancing with joy when life was good, growing frightened and hostile when food was scarce, when dangerous animals prowled near, or when fires were started by lightning near their homes. Yet there is no reason to assume they were any more hostile to one another than chimps or gorillas are. Even if we became a predator species through hunting, it would have been highly unnatural for us, as a mammalian species, to kill our own kind. The question may be, who did we recognize as our own kind?
It's easy to imagine how exciting it must have been when truly new improvements were invented. Who were the first people to carry burning sticks to their caves, learning to feed flames without letting them spread, learning to cover coals so they could be re-lit the next day or carried to a new home. How proud they must have been to teach such discoveries to their clan or tribe.
Like apes, humans had very flexible, expressive bodies and a natural talent for imitation. Human language probably began with dances and making decorative marks on their ever more naked bodies, to show each other, and later remind each other, of their experiences. Wearing clothing gave opportunity for elaboration into special costumes with headdresses and adornments as they created these rituals. We can imagine them dancing their hunting adventures, copying animals in courtship dances, and so on.
We can also guess that the sounds they made as they danced took on meaning, eventually becoming spoken words that were symbols for actions and things, just as their drawings on rock or on the ground became picture symbols. Once there was spoken language, it must have been much easier for them to learn and teach ever more complicated ways of life to one another.
Quite as the ancient bacteria had gotten together to do different jobs within the same cell walls, and as the cells of protist colonies, or the ants of ant colonies, divided their jobs among themselves, so humans now organized themselves into communities where different people did different jobs. Some hunted or fished; others scraped skins for clothing. Some became specialists in making tools or baskets or clay pots, which were hardened in fires. Some were no doubt better than others at drawing, dancing, or telling stories. And some became leaders -- wiser elders, chiefs or medicine people -- who organized jobs, drew up rules to live by, and made decisions on what to do when others could not agree.
Human communities, as they got larger and more complex, evolved leadership and governments just as eukaryote cells had evolved nuclei and just as animal bodies had evolved brains. Every holon that grows larger and more complicated must evolve some way of organizing itself to simplify and manage its complexity if it is to survive. When human communities got too large, they split up, or budded off, into new colonies, thus reproducing themselves much as ancient bacteria had.
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Among the oldest artifacts of Stone Age societies are motherly female images carved in stone or modeled in clay. Some of the oldest stone-age temples we have found were actually built in the shape of human female bodies, such as those in Malta, or in mounds that symbolized them, with internal womb chambers and birth passages, as in Newgrange, Ireland. So many such images and temples have been found by now, without any male images from the same times, say of hunters or warriors, that it is clear their makers were more interested in the giving of life than in the taking of it.
The giving of life is actually a lifelong business of feeding and otherwise nurturing people. Early humans probably began agriculture simply by leaving pits and seeds along their habitual tracks, as Amazon hunting cultures still do today. This rearranges ecosystems favorably for humans -- a kind of intermediate stage between gathering and gardening. Gradually they learned to grow reliable food supplies in their settlements and to keep and breed captive animals. Where climate and soil permitted, they organized themselves into villages with fields. The art of agriculture evolved from simply planting seeds to selecting the best seeds from each harvest for planting and giving as gifts, as well as to preparation of food for storage against times of need. As humans cleared larger and larger stretches of land, they began to seriously alter their environments, eliminating some species to nurture others, changing the genetic identity of plants and animals through their selection.
The agricultural revolution of the Stone Age was no doubt the greatest transition in human history, forging our destiny as a species that would change the face of the whole planet, destroying and rearranging things to our desire. Evidence suggests it all began peacefully and modestly with simple agricultural techniques for growing plant foods and keeping herds of animals for milk and meat and wool. In nurturing one another, people learned to spin yarn and weave cloth, to mold clay into vessels, to make houses of earthen bricks and furniture of wood. They learned to smelt metals from the earth for making images of worship, adornments to wear, and stronger tools, as well as for weapons.
They made musical instruments and danced and sang in worship of deities as well as to celebrate and tell colorful stories about their world and themselves. Some of those stories were reports, others were used as lessons, still more were told just to exaggerate, boast and entertain. We assume it was difficult for early people to explain their world to themselves -- that nature was an incomprehensible and unpredictable power to them and death a frightening mystery -- but this is not really likely. Today's surviving indigenous cultures -- tribal cultures still living on their ancestral lands -- have a much closer relationship with nature than does our technological society. Those that have been able to maintain their ancient ways despite all efforts by conquerors to destroy them, tend to see themselves as active and responsible co-creators of their ecosystems, something our dominant culture needs badly to learn from them. More on this in Chapter 19.
When we continue the story of human social evolution in the Stone Age and after, we will see that sustained violence among humans was quite likely a distortion of our humanity that came fairly late on the scene of human civilization. This should give us hope that our violent phase may be a temporary aberration from which we may recover. But let us first take a look back and reflect on the fact that for the greater part of our existence we were not so different from the rest of the animal world.
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Looking at ourselves today, it's hard to see humans as natural animals. But from Gaia's perspective that is just what we are -- and a very new animal species at that. For most of our history we did little more than mimic adults as children, mate and give birth, shelter and care for our young, gather food, defend ourselves and our homes against other animals, then rest or play with one another before we fell asleep to dream our restless dreams. Compared with the few million years in which human life was not very different from that of other mammals, our civilizations are still a very new development in a still juvenile species.
Imagine squeezing the four and a half billion years of Earth's existence into just twenty-four hours. While bacteria were born long before dawn and had the world to themselves until midday, humans came on the scene only for the very last minute before midnight! And only in the last second of that minute have we formed settled societies we call civilizations. We really have just begun to become fully human. Consider the experience whales have gained being already in their present form for some thirty millions of years.
Since people evolved -- however recently by these timescales -- we have survived many ice ages, which were believed until now to have been abnormal times for our planet. Lovelock and others presently working out Gaian physiology suggest that ice ages may be the Gaian norm during phases when continents are separate and spread out. Between these phases the Earth seems to warm up, creating periods between the waves of ice ages that are abnormally warm, like fevers. We now know of seventeen distinct ice age phases, most of which occurred before humans evolved.
Ice ages are only a few degrees of temperature colder on the average than the times between them, though we sensitive creatures consider them great extremes. In any case, during ice ages, great patches of ice move, as we know, from the poles over parts of the Earth that are warm between ice ages. As more ice is produced, the sea level is lowered and more land is exposed near the equator -- as much land as there is in the whole continent of Africa. When the ice recedes again, these areas are flooded, but ice-covered areas warm up, melt the ice, and produce rich new forests and grasslands.
Humans were apparently driven ahead of the great sheets of ice when they advanced, and humans later followed in their wake as the ice sheets receded. They wandered to places that were rich in food and water and settled down until, many generations later, a new wave of ice drove them back. By the time the last ice age was over, around ten thousand years ago, people had spread themselves out over much of the Earth's land, taking with them their early civilizations, their ways of changing the land, their seeds, and their stock. But before we go on with their history, let's look a bit more closely at the spectacular brains that made all this possible.