Memes about the history of the universe and the evolution of life on Earth to build into a timeline.
Folksonomies: history enlightenment big history
Man has been here 32,000 years. That it took a hundred million years to prepare the world for him is proof that that is what it was done for. I suppose it is. I dunno. If the Eiffel tower were now representing the world's age, the skin of paint on the pinnacle-knob at its summit would represent man's share of that age; & anybody would perceive that that skin was what the tower was built for. I reckon they would. I dunno.
Eventually, many billions of years ago, a molecule was formed that had a remarkable capability. It was able to produce, out of the molecular building blocks of the surrounding waters, a fairly accurate copy of itself. In such a molecular system there is a set of instructions, a molecular code, containing the sequence of building blocks from which the larger molecule is constructed. When, by accident, there is a change in the sequence, the copy is likewise changed. Such a molecular system – capable of replication, mutation, and replication of its mutations – can be called "alive." It is a collection of molecules that can evolve by natural selection. Those molecules able to replicate faster, or to reprocess building blocks from their surroundings into a more useful variety, reproduced more efficiently than their competitors – and eventually dominated.
But conditions gradually changed. Hydrogen escaped to space. Production of the molecular building blocks declined. The foodstuffs formerly available in great abundance dwindled. Life was expelled from the molecular Garden of Eden. Only those simple collections of molecules able to transform their surroundings, able to produce efficient molecular machines for the conversion of simple into complex molecules, were able to survive. By isolating themselves from their surroundings, by maintaining the earlier idyllic conditions, those molecules that surrounded themselves by membranes had an advantage. The first cells arose.
With molecular building blocks no longer available for free, organisms had to work hard to make such building blocks. Plants are the result. Plants start with air and water, minerals and sunlight, and produce molecular building blocks of high complexity. Animals, such as human beings, are parasites on the plants.
Changing climate and competition among what was now a wide diversity of organisms produced greater and greater specialization, a sophistication of function, and an elaboration of form. A rich array of plants and animals began to cover the Earth. Out of the initial oceans in which life arose, new environments, such as the land and the air, were colonized. Organisms now live from the top of Mount Everest to the deepest portions of the abyssal depths. Organisms live in hot, concentrated solutions of sulfuric acid and in dry Antarctic valleys. Organisms live on the water adsorbed on a single crystal of salt.
Life forms developed that were finely attuned to their specific environments, exquisitely adapted to the conditions. But the conditions changed. The organisms were too specialized. They died. Other organisms were less well adapted, but they were more generalized. The conditions changed, the climate varied, but the organisms were able to continue. Many more species of organisms have died during the history of the Earth than are alive today. The secret of evolution is time and death.
Among the adaptations that seem to be useful is one that we call intelligence. Intelligence is an extension of an evolutionary tendency apparent in the simplest organisms – the tendency toward control of the environment. The standby biological method of control has been the hereditary material: Information passed on by nucleic acids from generation to generation – information on how to build a nest; information on the fear of falling, or of snakes, or of the dark; information on how to fly south for the winter. But intelligence requires information of an adaptive quality developed during the lifetime of a single individual. A variety of organisms on the Earth today have this quality we call intelligence: The dolphins have it, and so do the great apes. But it is most evident in the organism called Man.
In Man, not only is adaptive information acquired in the lifetime of a single individual, but it is passed on extra-genetically through learning, through books, through education. It is this, more than anything else, that has raised Man to his present pre-eminent status on the planet Earth.
We are the product of 4.5 billion years of fortuitous, slow, biological evolution. There is no reason to think that the evolutionary process has stopped. Man is a transitional animal. He is not the climax of creation.
Sex and death evolved – processes that vastly increased the rate of natural selection. Some organisms evolved hard parts, climbed onto, and survived on the land. The pace of production of more complex forms accelerated. Flight evolved. Enormous four-legged beasts thundered across the steaming jungles. Small beasts emerged, born live, instead of in hard-shelled containers filled with replicas of the early oceans. They survived through swiftness and cunning – and increasingly long periods in which their knowledge was not so much preprogrammed in selfreplicating molecules as learned from parents and experiences.
All the while, the climate was variable. Slight variations in the output of sunlight, the orbital motion of the planet, clouds, oceans, and polar icecaps produced climatic changes – wiping out whole groups of organisms and causing the exuberant proliferation of other, once insignificant, groups.
And then … the Earth grew somewhat cold. The forests retreated. Small arboreal animals climbed down from the trees to seek a livelihood on the savannas. They became upright and tool-using. They communicated by producing compressional waves in the air with their eating and breathing organs. They discovered that organic material would, at a high enough temperature, combine with atmospheric oxygen to produce the stable hot plasma called fire. Postpartum learning was greatly accelerated by social interaction. Communal hunting developed, writing was invented, political structures evolved, superstition and science, religion and technology.
And then one day there came to be a creature whose genetic material was in no major way different from the self-replicating molecular collectives of any of the other organisms on his planet, which he called Earth. But he was able to ponder the mystery of his origins, the strange and tortuous path by which he had emerged from star-stuff. He was the matter of the cosmos, contemplating itself. He considered the problematical and enigmatic question of his future. He called himself Man. He was one of the starfolk. And he longed to return to the stars.
Once upon a time, about ten or fifteen billion years ago, the universe was without form. There were no galaxies. There were no stars. There were no planets. And there was no life. Darkness was upon the face of the deep. The universe was hydrogen and helium. The explosion of the Big Bang had passed, and the fires of that titanic event – either the creation of the universe or the ashes of a previous incarnation of the universe – were rumbling feebly down the corridors of space.
But the gas of hydrogen and helium was not smoothly distributed. Here and there in the great dark, by accident, somewhat more than the ordinary amount of gas was collected. Such clumps grew imperceptibly at the expense of their surroundings, gravitationally attracting larger and larger amounts of neighboring gas. As such clumps grew in mass, their denser parts, governed by the inexorable laws of gravitation and conservation of angular momentum, contracted and compacted, spinning faster and faster. Within these great rotating balls and pinwheels of gas, smaller fragments of greater density condensed out; these shattered into billions of smaller shrinking gas balls.
Compaction led to violent collisions of the atoms at the centers of the gas balls. The temperatures became so great that electrons were stripped from protons in the constituent hydrogen atoms. Because protons have like positive charges, they ordinarily electrically repel one another. But after a while the temperatures at the centers of the gas balls became so great that the protons collided with extraordinary energy – an energy so great that the barrier of electrical repulsion that surrounds the proton was penetrated. Once penetration occurred, nuclear forces – the forces that hold the nuclei of atoms together – came into play. From the simple hydrogen gas the next atom in complexity, helium, was formed. In the synthesis of one helium atom from four hydrogen atoms there is a small amount of excess energy left over. This energy, trickling out through the gas ball, reached the surface and was radiated into space. The gas ball had turned on. The first star was formed. There was light on the face of the heavens.
The stars evolved over billions of years, slowly turning hydrogen into helium in their deep interiors, converting the slight mass difference into energy, and flooding the skies with light. There were in these times no planets to receive the light, and no life forms to admire the radiance of the heavens.
The conversion of hydrogen into helium could not continue indefinitely. Eventually, in the hot interiors of the stars, where the temperatures were high enough to overcome the forces of electrical repulsion, all the hydrogen was consumed. The fires of the stars were stoked. The pressures in the interiors could no longer support the immense weight of the overlying layers of star. The stars then continued their process of collapse, which had been interrupted by the nuclear fires of a billion years before.
In contracting further, higher temperatures were reached, temperatures so high that helium atoms – the ash of the previous epoch of nuclear reaction – became usable as stellar fuel. More complex nuclear reactions occurred in the insides of the stars – now swollen, distended red giant stars. Helium was converted to carbon, carbon to oxygen and magnesium, oxygen to neon, magnesium to silicon, silicon to sulfur, and upward through the litany of the periodic table of the elements – a massive stellar alchemy. Vast and intricate mazes of nuclear reactions built up some nuclei. Others coalesced to form much more complex nuclei. Still others fragmented or combined with protons to build only slightly more complex nuclei.
But the gravity on the surfaces of red giants is low, because the surfaces have expanded outward from the interiors. The outer layers of red giants are slowly dissipated into interstellar space, enriching the space between the stars in carbon and oxygen and magnesium and iron and all the elements heavier than hydrogen and helium. In some cases, the outer layers of the star were slowly stripped off, like the successive skins of an onion. In other cases, a colossal nuclear explosion rocked the star, propelling at immense velocity into interstellar space most of the outside of the star. Either by leakage or explosion, by dissipation slow or dissipation fast, star-stuff was spewed back to the dark, thin gas from which the stars had come.
But here, later generations of stars were aborning. Again the condensations of gas spun their slow gravitational pirouettes, slowly transmogrifying gas cloud into star. But these new second- and third-generation stars were enriched in heavy elements, the patrimony of their stellar antecedents. Now, as stars were formed, smaller condensations formed near them, condensations far too small to produce nuclear fires and become stars. They were little dense, cold clots of matter, slowly forming out of the rotating cloud, later to be illuminated by the nuclear fires that they themselves could not generate. These unprepossessing clots became the planets: Some giant and gaseous, composed mostly of hydrogen and helium, cold and far from their parent star; others, smaller and warmer, losing the bulk of their hydrogen and helium by a slow trickling away to space, formed a different sort of planet – rocky, metallic, hard-surfaced.
These smaller cosmic debris, congealing and warming, released small quantities of hydrogen-rich gases, trapped in their interiors during the processes of formation. Some gases condensed on the surface, forming the first oceans; other gases remained above the surface, forming the first atmospheres – atmospheres different from the present atmosphere of Earth, atmospheres composed of methane, ammonia, hydrogen sulfide, water, and hydrogen – an unpleasant and unbreathable atmosphere for humans. But this is not yet a story about humans.
Starlight fell on this atmosphere. Storms were driven by the Sun, producing thunder and lightning. Volcanoes erupted, hot lava heating the atmosphere near the surface. These processes broke apart molecules of the primitive atmosphere. But the fragments reassorted into more and more complex molecules, falling into the early oceans, there interacting with each other, falling by chance upon clays, a dizzying process of breakdown, resynthesis, transformation – slowly moving toward molecules of greater and greater complexity, driven by the laws of physics and chemistry. After a time, the oceans achieved the constituency of a warm dilute broth.
Among the innumerable species of complex organic molecules forming and dissipating in this broth there one day arose a molecule able crudely to make copies of itself – a molecule which weakly guided the chemical processes in its vicinity to produce molecules like itself – a template molecule, a blueprint molecule, a self-replicating molecule. This molecule was not very efficient. Its copies were inexact. But soon it gained a significant advantage over the other molecules in the early waters. The molecules that could not copy themselves did not. Those that could, did. The number of copying molecules greatly increased.
As time passed, the copying process became more exact. Other molecules in the waters were reprocessed to form the jigsaw puzzle pieces to fit the copying molecules. A minute and imperceptible statistical advantage of the molecules that could copy themselves was soon transformed by the arithmetic of geometrical progression into the dominant process in the oceans.
More and more elaborate reproductive systems arose. Those systems that copied better produced more copies. Those that copied poorly produced fewer copies. Soon most of the molecules were organized into molecular collectives, into self-replicating systems. It was not that any molecules had the glimmering of an idea or the ghostly passage of a need or want or aspiration; merely, those molecules that copied did, and soon the face of the planet became transformed by the copying process. In time, the seas became full of these molecular collectives, forming, metabolizing, replicating … forming, metabolizing, replicating … forming, metabolizing, mutating, replicating… Elaborate systems arose, molecular collectives exhibiting behavior, moving to where the replication building blocks were more abundant, avoiding molecular collectives that incorporated their neighbors. Natural selection became a molecular sieve, selecting out those combinations of molecules best suited by chance to further replication.
All the while the building blocks, the foodstuffs, the parts for later copies, were being produced, mainly by sunlight and lightning and thunder – all driven by the nearby star. The nuclear processes in the insides of the stars drove the planetary processes, which led to and sustained life.
As the supply of foodstuffs gradually was exhausted, a new kind of molecular collective arose, one able to produce molecular building blocks internally out of air and water and sunlight. The first animals were joined by the first plants. The animals became parasites upon the plants, as they had been earlier on the stellar manna falling from the skies. The plants slowly changed the composition of the atmosphere; hydrogen was lost to space, ammonia transformed to nitrogen, methane to carbon dioxide. For the first time, oxygen was produced in significant quantities in the atmosphere – oxygen, a deadly poisonous gas able to convert all the self-replicating organic molecules back into simple gases like carbon dioxide and water.
But life met this supreme challenge: In some cases by burrowing into environments where oxygen was absent, but – in the most successful variants – by evolving not only to survive the oxygen but to use it in the more efficient metabolism of foodstuffs.
Pelorat said, "Tortoises are cold-blooded. Terminus doesn't have any, but some worlds do. They are shelled creatures, very slow-moving but long-living.”
"Well, then, isn't it better to be a human being than a tortoise; to move quickly whatever the temperature, rather than slowly? Isn't it better to support high-energy activities, quickly contracting muscles, quickly working nerve fibers, intense and long-sustained thought-than to creep slowly, and sense gradually, and have only a blurred awareness of the immediate surroundings? Isn't it?"
"Granted," said Trevize. "It is. What of it?"
"Well, don't you know you must pay for warm-bloodedness? To maintain your temperature above that of your surroundings, you must expend energy far more wastefully than a tortoise must. You must be eating almost constantly so that you can pour energy into your body as quickly as it leaks out. You would starve far more quickly than a tortoise would, and die more quickly, too. Would you rather be a tortoise, and live more slowly and longer? Or would you rather pay the price and be a quick-moving, quick-sensing, thinking organism?"
The first Australopithecine to be discovered, and the type specimen of the genus, was the so-called Taung Child. At the age of three and a half the Taung Child was eaten by an eagle. The evidence is that damage marks to the eye sockets of the fossil are identical to marks made by modern eagles on modern monkeys as they rip out their eyes. Poor little Taung Child, shrieking on the wind as you were borne aloft by the aquiline fury, you would have found no comfort in your destined fame, two and a half million years on, as the type specimen of Australopithecus africanus. Poor Taung mother, weeping in the Pliocene.
Inside my skull is a brain that was designed to exploit the conditions of an African savanna between 3 million and 100,000 years ago. When my ancestors moved into Europe (I am a white European by descent) about 100,000 years ago, they quickly evolved a set of physiological features to suit the sunless climate of northern latitudes: pale skin to prevent rickets, male beards, and a circulation relatively resistant to frostbite. But little else changed: Skull size, body proportions, and teeth are all much the same in me as they were in my ancestors 100,000 years ago and are much the same as they are in a San tribesman from southern Africa. And there is little reason to believe that the gray matter inside the skull changed much, either. For a start, 100,000 years is only three thousand generations, a mere eye blink in evolution, equivalent to a day and a half in the life of bacteria. Moreover, until very recently the life of a European was essentially the same as that of an African. Both hunted meat and gathered plants. Both lived in social groups. Both had children dependent on their parents until their late teens. Both used stone, bone, wood, and fiber to make tools. Both passed wisdom down with complex language. Such evolutionary novelties as agriculture, metal. and writing arrived less than three hundred generations ago, far too recently to have left much imprint on my mind.
There is, therefore, such a thing as a universal human nature, common to all peoples. If there were descendants of Homo erectus still living in China, as there were a million years ago, and those people were as intelligent as we are, then truly they could be said to have different but still human natures.'* They might perhaps lave no lasting pair bonds of the kind we call marriage, no concept of romantic love, and no involvement of fathers in parental care. We could have some very interesting discussions with them about such matters. But there are no such people. We are all one close family, one small race of the modern Homo sapiens people who lived in Africa until 100,000 years ago, and we all share the nature of that beast.
Then for more than a million years people lived in a way that couldn't have changed much. They inhabited grasslands and woodland savannas, first in Africa, later in Eurasia, and eventually in Australasia and the Americas. They hunted animals for food, gathered fruits and seeds, and were highly social within each tribe but hostile toward members of other tribes. Don Symons refers to this combination of time and place as the "environment of evolutionary adaptedness," or EEA, and he believes it is central to human psychology. People cannot be adapted to the present or the future; they can only be adapted to the past. But he readily admits that it is hard to be precise about exactly what lives people lived in the EEA. They probably lived in small bands; they were perhaps nomadic; they ate both meat and vegetable matter; they presumably shared the features that are universal among modern humans of all cultures: a pair bond as an institution in which to rear children, romantic love, jealousy and sexually induced male violence, a female preference for men of high status, a male preference for young females, warfare between bands, and so on. There was almost certainly a sexual division of labor between hunting men and gathering women, something unique to people and a few birds of prey. To this day, among the Ache people of Paraguay, men specialize in acquiring those foods that a woman encumbered with a baby could not manage to—meat and honey. for example."
Kim Hill, at the University of New Mexico, argues that there was no consistent EEA, but he nonetheless agrees that there were universal features of human life that are not present today but that have hangover effects. Everybody knew or had heard of nearly all the people they were likely to meet in their lives: There were no strangers, a fact that had enormous importance for the history of trade and crime prevention, among other things. The lack of anonymity meant that charlatans and tricksters could rarely get away with their deceptions for long.
Another group of biologists at Michigan rejects these EEA arguments altogether with two arguments. First, the most critical feature of the EEA is still with us. It is other people. Our brains grew so big not to make tools but to psychologize one another. The lesson of socioecology is that our mating system is determined not by ecology but by other people—by members of the same gender and by members of the other gender. It is the need to outwit and dupe and help and teach one another that drove us to be ever more intelligent.
Second, we were designed above all else to be adaptable. We were designed to have all sorts of alternative strategies to achieve our ends. Even today, existing hunter-gatherer societies show enormous ecological and social variation, and they are probably an unrepresentative sample because they mostly occupy deserts and forests, which were not mankind's primary habitat. Even in the time of Homo erectus, let alone more modern people, there may have been specialized fishing, shore-dwelling, hunting, or plant-gathering cultures. Some of these may well have afforded opportunities for wealth accumulation and polygamy. In recent memory there was a preagricultural culture among the salmon-fishing Indians of the Pacific Northwest of America that was highly polygamous. If the local hunter-gathering economy favored it, men were capable of I being polygamous and women were capable of joining harems over the protests of the preceding co-wives. If not, then men were capable of being good fathers and women jealous monopolizers. In other words, mankind has many potential mating systems, one for each circumstance.
This is supported by the fact that larger, more intelligent and more social animals are generally more flexible in their mating systems than smaller, dumber, or more solitary ones. Chimps go from small feeding bands to big groups depending on the nature of the food supply. Turkeys do the same. Coyotes hunt in packs when their food is deer but hunt alone when their food is mice. These food-induced social patterns themselves induce slightly different mating patterns.
We stand upright-after a little practice-on a ship that rolls because we possess an array of sensory nerve cells buried in our muscles, skin, and joints. The function of these sensors is to provide a constant flow of information to the brain about the movements and location in space of the various parts of our bodies, as well as the environmental forces currently acting on them. We also have a pair of balance organs associated with our ears which work like spirit-levels, each having a bubble moving in a fluid medium to record any change in the position of the head; and we have our eyes to scan the horizon and tell us how we stand in relation to it. All this flow of information is processed by the brain, usually at an unconscious level, and is immediately compared with our consciously intended stance at the time. If we have decided to stand level in spite of the ship's motion, perhaps to look at the receding harbour through binoculars, this chosen posture is the reference point used by the brain to compare with departures from it caused by the rolling of the vessel. Thus our sense organs continually inform the brain about our stance, and counter-instructions pass constantly from the brain down the motor nerves to the muscles. As we tip from the vertical, the push-and-pull of these muscles changes, so as continuously to maintain the upright position.
This process of comparing wish with actuality, of sensing error and then correcting it by the precise application of an opposing force enables us to stand erect. Walking or balancing on one leg is more difficult and takes longer to learn; riding a bicycle is even trickier, but this also can become second nature through the same active control process which keeps us upright.