Origin Story
by David Christian
(Allen Lane, 2018)
To understand the history of humanity, you have to understand how such a strange species evolved, which means learning about the evolution of life on planet Earth, which means learning about the evolution of planet Earth, which means learning about the evolution of stars and planets, which means knowing about the evolution of the universe.
Page viii.
All origin stories unify knowledge, even the origin stories of nationalist historiography.
Page ix.
Increasing cross-cultural contacts have shown ow embedded all origin stories and religions are in local customs and environments. That is why globalization and the spread of new idea corroded faith in traditional knowledge.
Page ix.
Build these vast maps of our universe and its past partly because we have large brains, and, like all brainy organisms, we use our brains to create internal maps of the world.
Page 4.
We can create simple maps of a fantastically complicated reality, and we know that those maps correspond to important aspects of the real world.
Page 4.
What makes humans different from all other brainy species is language, a communication tool that is extraordinarily powerful because it allows us to share our individual world maps and, in so doing, form maps much larger and more detailed than those created by an individual brain.
Page 4.
In a globally connected world, there are so many local origin stories for people’s trust and attention that they get in one another’s way. So most modern educators focus on parts of the story, and students learn about their world discipline by discipline.
Pages 8-9.
We do know that when our universe emerged from a vast foam of energy, it was extremely simple. And simplicity is still its default condition. After all, most of our universe is cold, dark, empty space.
Page 11.
Understanding how complex things emerged and what Goldilocks conditions allowed them to emerge is a great way of understanding ourselves and the world we live in today.
Page 11.
The early universe had no stars, no planets, and no living organisms. Then, step by step, entirely new things began to appear.
Page 11.
The appearance of something new and more complex than what preceded it, something with new emergent properties, always seems as miraculous as the birth of a baby, because the general tendency of the universe is to get less complex and more disorderly.
Page 12.
It’s as if the creation of our universe was so violent that any information about what it came out of was erased.
Page 20.
In modern quantum physics, it is impossible to determine precisely the position and motion of subatomic particles. This means you can never say for sure that a particular region of space is empty, and that means that emptiness is tense with the possibility that something might appear.
Page 21.
The emergence of something with distinctive new qualities is always magical.
Page 22.
New things with new properties emerge from already existing things and forces that are arranged in new ways.
Page 22.
In the extreme temperatures of the big bang, almost anything was possible. But as temperatures dropped, possibilities narrowed. Distinct entities began to emerge like ghosts within the chaotic fog of e cooling universe, entities that could not exist in the violent cauldron of the big bang itself.
Page 23.
Understanding dark energy is one of the great challenges of contemporary science.
Page 24.
Until just over a century ago, scientists and philosophers assumed that matter and energy were distinct. We now know that matter is really a highly compressed formof energy.
Page 24.
So powerful is entropy that it is not easy to understand how any structures appeared in the first place.
Page 27.
Almost three-quarters of all the atoms in it are hydrogen, and most of the rest are helium.
Page 30.
A lot more matter consists of dark matter, stuff we don’t yet understand, though we know it exists because its gravitational pull determines the structure and distribution of galaxies.
Page 30.
Heat is really a measure of the motion of atoms.
Page 30.
The first clue that the big bang really happened was the discovery that the universe is expanding.
Page 31.
Over time, astronomers have learned how to tease out more and more information about stars from the light they emit.
Page 32.
Early in the twentieth century, most astronomers believed that the entire universe was contained within our galaxy, the Milky Way.
Page 34.
Today we know of no astronomical objects older than 13.82 billion years, which is a strong argument in favor of big bang cosmology. After all, if the universe were unchanging and eternal, there really should be lots of objects more than 13.8 billion years old.
Page 36.
The discovery of cosmic microwave background radiation persuaded most astronomers that the big bang was real because no other theory could explain this all-pervading radiation.
Page 37.
Stars are held together by flows of energy generated in their cores. Living organisms, including you and me, are held together by delicate and precisely directed flows of energy managed by intricate metabolic processes in our cells. In a post-big bang universe, it takes work to build and maintain new complex structures.
Page 40.
Together, gravity and matter provided the Goldilocks conditions for the emergence of stars and galaxies.
Page 42.
We know the early universe was homogenous because we can measure temperature differences in the CMBR, and we find that the hottest parts of the early universe were only about one one-hundredth of a degree warmer than the coolest parts. Page 42.
The gravity began to shape this unpromising material into something more interesting. While the big bang was pushing space apart, gravity was hustling around trying to pull energy and matter together.
Page 43.
Einstein made another important prediction about gravity: It was a form of energy, so, like electromagnetism or sound, it ought to generate waves.
Page 43.
Once it got going, gravity took just a few hundred million years to turn the smooth particle mist of the early universe into a messier and lumpier space full of stars and galaxies.
Page 44.
The star’s life history will depend primarily on its birth mass: how much stuff it contains at the start. Massive stars generate more gravitational pressure, so they are much hotter than stars with less mass.
Page 46.
Increasing complexity is not a triumph over entropy. Paradoxically, the flows of energy that sustain complex things (including you and me) are helping entropy with its bleak task of slowly breaking down all forms of order and structure.
Page 48.
Hydrogen and helium were the first elements to be made because they are the simplest.
Page 48.
Visible light make sup only a tiny portion of the energies emitted by stars and galaxies. Modern telescopes let astronomers study emissions at all frequencies of the electromagnetic spectrum.
Page 54.
The ideal environment seems to be near a star, but not too near, in regions with sustained but gentle flows of free energy.
Page 57.
About 98 percent of the mass of interstellar dust clouds consists of hydrogen and helium.
Page 57.
Spectroscopes can tell us what elements are present in galactic clouds and in what amounts.
Page 57.
Don’t think of atoms as solid balls of matter. They consist almost entirely of empty space.
Page 58.
Quantum physics showed that we can never pin down their exact speed or position. We can tell where an electron probably is, but neve exactly where it is, because any attempt to locate it will require the use of energy (imagine shining a flashlight on it), and electrons are so light that the energy used to detect them will alter their speed and trajectory.
Page 58.
The basic rules of chemistry seem to be universal. We know this because spectroscopes show that many of the simple molecules we find on Earth also exist in interstellar dust clouds.
Page 60.
The formation of planetary systems is a messy and chaotic process, a by-product of star formation in chemically enriched regions of space.
Page 62.
All planetary bodies are cooler than stars, and chemically richer and more diverse, and that’s why they provided Goldilocks conditions that allowed the building of new forms of complexity. Eventually, at least one of these objects, and probably many more, generated life.
Page 64.
The young Earth heated up and melted. It was heated by the violent collisions of accretion, by the presence of radioactive elements (created in the supernova that provided much of the material for our solar system), and by increasing pressure as it grew in size. Eventually, the young Earth was so hot that much of it melted into a gooey sludge, and as it liquefied, its different layers sorted themselves by density, giving it the structure it has today.
Page 65.
As Earth spun, the core generated a magnetic field that shielded the surface from the damaging charged particles of the solar wind.
Page 65.
Beneath the oceans, the crust is sometimes just five kilometers thick, but under the continents, it can be up to fifty kilometers thick.
Pages 65-66.
We can track the movement of the surface using GPS systems, and we know that crustal plates on the surface move around at about the speed that your fingernails grow; the fastest of them cruise at about twenty-five centimeters a year.
Page 66.
Despite what Hollywood might have us believe, we cannot dig deep into Earth.
Page 67.
Techniques, based on careful study of processes such as radioactive decay, as well as the development of new instruments for measuring them precisely, have given us the timelines around which the modern origin story is built.
Page 70.
If life exists elsewhere, it might look so strange that we wouldn’t recognize it.
Page 75.
Cells are the smallest units of life that can replicate independently.
Page 76.
The appearance (or, perhaps, illusion) of purposefulness is new. It is not a feature of the other complex entities we have seen so far.
Page 76.
Living organisms constantly seek out new flows of energy from their environments in order to maintain themselves in a state that is complex but unstable.
Page 77.
The average human takes in about 2,500 calories each day, about 10.5 million joules (a measure of work or energy; a calorie represents about 4,184 joules). Divide this by the 86,400 seconds in a day, and an individual mobilizes about 120 joules every second. This is the “power rating” of a human being: 120 watts, just slightly greater than the power rating of many traditional lightbulbs.
Page 77.
Energy causes change, so you can usually see it at work, but information directs change, often from the shadows.
Page 78.
All forms of life require mechanisms to interpret local information. … In fact, all living organisms are informavores. They all consume information, and the mechanisms they use for reading and responding to local information - whether they are eyes and tentacles or muscles and brains - account for much of the complexity of living organisms.
Page 79.
Natural selection is a fundamental idea in modern biology because it is an extraordinarily powerful driver of increasing complexity. Natural selection filters out some genetic possibilities, allowing only those compatible with local rules.
Page 83.
In the biological realms, it is the local rules of particular environments, not the universal rules of physics, that determine what survive.
Page 83.
Natural selection links necessity and change. Variation provides multiple possibilities; naturel selection uses local rules to pick out those that will work under local conditions.
Page 83.
The idea of natural selection shocked Darwin’s contemporaries, because it seemed to do away with the nee for a creator god. And that idea was fundamental to the Christian origin story that most people accepted in Victorian England.
Page 84.
We should expect the most interesting chemistry to be on planets whose average surface temperatures lie roughly between zero and one hundred degrees Celsius, the freezing and boiling points, respectively, for water. That’s rare, but our Earth happens to be at just the right distance from the sun to have liquid water.
Page 87.
Life appeared early in the history of planet Earth, and that suggests that creating simple forms of life may not be too hard where the right Goldilocks conditions exist.
Page 89.
Though they don’t know exactly what it looked like, biologists refer to the first living organism as Luca (or LUCA, or “last universal common ancestor”).
Page 90.
While proteins are made from strings of amino acids, and membranes are made form phospholipids, DNA and RNA are made from long strings of nucleotides. These are sugar molecules to which are attached small groups of molecules knows as bases. The bases come in four types: adenine (A), cytosine (C), guanine (G), and thymine (T).
Page 95.
Together, Earth and life make up the biosphere.
Page 99.
One of modern science’s most important paradigms: plate tectonics.
Page 101.
Humans have been able to visualize Earth’s surface only in the past five hundred years, when, for the first time, they were able to sail all around it.
Page 101.
Hot magmas rising from deep within the Earth circulate under the crust, like water boiling in a saucepan. It is these convection currents of semiliquid rock and lava that move the tectonic plates floating above them.
Page 104.
Plate tectonics was a powerful unifying idea. It explained and showed the links between many different processes, form earthquakes to mountain building and the movement of continents. It explains why so many violent geological events take place where tectonic plates meet and grind their way past, over, and under each other. Plate tectonics also explains why Earth’s surface is so dynamic, as it is continually renewed by the arrival of new materials from the mantle, while surface material, in turn, is subducted deep into the Earth.
Page 105.
At divergent margins … material rises from the mantle and pushes plates apart. Elsewhere, though, at convergent margins, plates are pushed together. If the two plates have about the same density - if, s ay, they both consist of granitic continental plates - then, like two bull walruses competing for mates, they will rear up. … But if two converging plates have different densities - if, say, one consists of heavy, basaltic oceanic crusts and the other of lighter granitic continental crust - the story is different. The heavier oceanic plate will dive under the lighter plate at a subduction zone.
Page 105.
Plate tectonics give planet Earth an exceptional chemical and geological dynamism.
Page 106.
Two major forces determine average temperatures at Earth’s surface: heat from the interior and heat from the sun.
Page 106.
A greenhouse atmosphere was one more important Goldilocks condition for life on the young Earth.
Page 107.
While tectonics builds mountains up, erosion grinds them down.
Page 108.
The tectonic conveyor belt removes carbon from the atmosphere, and that should eventually reduce carbon dioxide levels and generate colder climates. Today we know that much more carbon is buried within the mantle than is present on Earth’s surface or in its atmosphere.
Page 108.
All organisms alive today are related genetically. … if you zoom down to the level of cells, it’s hard to distinguish between a human being and an amoeba.
Page 110.
We can’t make sense of the biosphere’s recent history without understanding the much longer era of little life.
Page 113.
By about 3.5 billion years ago, a new evolutionary innovation, photosynthesis, was letting some organisms tap into flows of energy from the sun. This was life’s first energy bonanza.
Page 115.
Oxygen is an electron thief and will combine eagerly with any element that has spare electrons. That is why atoms that have had their electrons stolen are said to have been oxidized.
Page 117.
The appearance of an oxygen-rich atmosphere beginning about two and a half billion years ago (the “great oxygenation event”) transformed the biosphere.
Page 118.
Respiration is the reverse of photosynthesis and is really a way of releasing solar energy that has been captured and stored within cells through photosynthesis.
Page 120.
Respiration gives you the energy of fire without its destructiveness.
Page 120.
Even if bacterialike organisms are common in the universe, large organisms like us may be extremely rare.
Page 123.
is not just a matter of competition. Nor is it just a matter of constant divergence as new species appear. We also see collaboration, symbiosis, and even convergence.
Page 123.
Many molecular mechanisms had to be in place before you could think of building multicellular organisms.
Page 125.
Earth needed one more Goldilocks condition: stability. Life-friendly conditions are not enough. You also need those conditions to persist for a long time so that life can keep evolving and experimenting.
Page 126.
Somehow or other, our Earth avoided these dangers and remained life-friendly for more than three billion years. That was enough time for big life to evolve.
Page 126.
In fully multicellular organisms, each cell is so specialized and so interdependent that it cannot survive alone.
Page 128.
The rise of big life was driven by extreme climatic swings late in the Proterozoic eon.
Page 129.
With the emergence of huge numbers of organisms that got their energy by consuming other organisms, the biosphere became more complex, more diverse, and more hierarchical as energy from sunlight was passed through different trophic levels, from plants to animals and fungi.
Page 131.
Approximately 90 percent of the energy captured by photosynthesis is lost at each trophic level, so much less energy is available for the late links in the food chain. That’s why you find fewer animals than plants on Earth, and fewer carnivores than herbivores. But the fungi do well either way, as they recycle corpses.
Page 131.
To nineteenth-century paleontologists, life seemed to pop up, fully formed, which delights those who believed in a creator god. Now we know that life had already been around for three and a half billion years; it was just hard to see the evidence. What the Cambrian era marks is not the beginning of life but an exuberant adaptive radiation of multicellular life-forms.
Page 133.
The history of big life was an unpredictable and dangerous rollercoaster ride.
Page 135.
During mass extinctions, whole groups of species vanish suddenly and apparently randomly. Like human wars, mas extinctions took a horrifying toll. They were particularly rough on specialized species because extreme specialists, like modern koalas, had little room to maneuver in periods of rapid change. Mass extinctions were also hard on the largest organisms, which need more food and reproduce too slowly to keep up with rapid changes.
Page 135.
In an extreme greenhouse world, larger organisms survived only in the cooler polar environments in the far north and south of the vast supercontinent of Pangaea.
Page 137.
A flea can happily jump off a cliff. But for larger organisms, gravity was a problem. They needed bracing from girders of bone or wood if they were to stand up.
Page 138.
Amphibians evolved from fish that could breath out of water and walk in the shallows to drying lakes and rives, like modern lungfish. But all amphibians have to stay near water, where they lay their eggs. The first amphibians were the first large, land-based vertebrates.
Page 138.
Since about 370 million years ago, oxygen levels have mostly remained between 17 and 30 percent of the atmosphere. We know this because over this entire period researchers see evidence of spontaneous fires, and fires cannot ignite if oxygen levels fall much below 17 percent.
Page 139.
The first plants with woody skeletons that allowed them to stand up against gravity appeared about 375 million years ago, and the first forests appeared soon after.
Page 139.
Evolution was never a matter of chance alone. Some changes were more likely than others.
Page 141.
Being a giant often made good evolutionary sense. After all, larger organisms have fewer predators. Try getting your teeth into a blue whale! Large organisms also need less food for each until of body weight, and it/s usually easier for them to avoid the catastrophe of desiccation.
Page 141.
It seems likely that very large organisms flourished best when oxygen levels were highest, which usually meant during periods of low carbon dioxide and cooler climates.
Page 141.
Throughout the Triassic, Jurassic, and Cretaceous (form 250 million yuea5s ago to 65 million years ago), most mammals were small, burrowing creatures, a bit like modern-day rodents.
Page 143.
Mammals differ from reptiles and birds in crucial ways. The mammal brain has a neocortex, which makes mammals superb calculators. They have fur (yes, even humans have fur, though less than most mammals), and for the most part, mammals take more dare of their offspring.
Page 143.
All mammals nourish their young with milk from mammary glands. For paleontologists, the most visible distinguishing feature of mammal fossils is their teeth. Even the earliest mammal teeth have cusps so that the upper and lower teeth can mesh together, allowing them to chomp down on new types of food and grind it more efficiently than most reptiles.
Page 143.
But as organisms became larger and more complex, they needed more information about their environments. Natural selection equipped large organisms with a desire for more information, because good information was vital to their success.
Page 144.
No brainy creature (not even you or I) is in direct contact with its environment. Instead, we all live in a rich virtual reality constructed in our b rains. Our brains generate and constantly update maps of the most salient features of our bodies and our surroundings, just as climate scientists model changing environments today.
Page 144.
Emotions drive decision-making in all animals with large brains, and some emotions, like fear, are probably present in all vertebrates and maybe in some invertebrates, particularly the most intelligent ones such as the octopi. The preferences emotions create for particular outcomes and behaviours lie behind the human sense of meaning and ethics.
Page 145.
The state that we escribe as consciousness seems to be a mode of sharply focused attention summoned by the brain.
Page 145.
Add memory to these decision-making systems, and we have the foundations for complex learning, the ability to record the results of earlier decisions and use those records to make better decisions in the future.
Page 146.
Memory can store the results of decisions made consciously and use them for fast, automated responses.
Page 146.
The world of the dinosaurs vanished in just a few hours when a ten-to fifteen-kilometer-wide asteroid crashed into Earth. The crash caused a major extinction event, during which about half of all genera disappeared.
Page 147.
In the Hell Creek Formation, in Montana and Wyoming, you can find fossils of fish whose gills are full of glass from the asteroid impact.
Page 148.
As is typical in such crises, large species were particularly hard hit, because they need more energy, are less numerous, and reproduce more slowly than smaller creatures. That is why the large dinosaurs perished.
Page 148.
Flowering plants provided a food bonanza for those mammals with teeth designed to munch on fruit and seeds or on the many insets that also munched on flowering plants or helped pollinate them.
Page 150.
Though the first primates already existed in the world of dinosaurs, they flourished only after the dinosaurs had left the scene.
Page 151.
Because we humans can share individual maps of our surroundings, we have built up a rich collective understanding of space and time that lies behind all our origin stories.
Page 157.
Culturally, we humans are astonishingly diverse, and that is part of our power.
Page 158.
Why are primate brains so big? This may seem (pardon the pun) a no-brainer. Aren’t brains obviously a good thing? Not necessarily, because they guzzle energy. They need up to twenty times as much energy as the equivalent amount of muscle tissue. In human bodies, the brain uses 16 percent of available energy, though it accounts for just 2 percent of the body’s mass. That’s why, given the choice between brawn and brain, evolution has generally gone for more brawn less brain. And that’s why there are so few very brainy species.
Page 159.
Primates are sociable, because living in groups provides protection and support.
Page 160.
To live successfully with other members of your species, you have to keep track of the constantly changing relationships among family, friends, and enemies.
Page 160.
To lie in groups, you also need some insight into the brains of others.
Page 160.
Sociability, cooperation, and brainpower seem to have evolved together in the history of primates. Indeed, there seems to be rough correlation between the size of primate groups and the size of their brains.
Page 160.
The great apes (or hominids) include, today, the orangutans, gorillas, and chimpanzees, as well as humans.
Page 161.
Somewhere in Africa six or seven million years ago, there existed a creature form which modern humans and chimpanzees are both descended.
Page 161.
We are the only surviving hominin species. That is unusual, because until as recently as twenty or thirty thousand years ago, several different species of hominins cruised the savannas of Africa and Eurasia at the same time. The recent disappearance of other hominin species as we humans took up more and more land and resources is a sign of how dangerous we are.
Page 162.
Walking on two legs required rearrangements of the back, the hips, even the braincase. It also favored narrower hips, which made childbearing more difficult and dangerous.
Page 165.
Extreme braininess was not the first distinguishing feature of the hominis. Bipedalism was.
Page 165.
Tool use does not make them human, because we now know that toolmaking is not unique to humans.
Page 166.
The importance of social calculations shows up clearly in the human brain structure, which devotes an exceptional number of neuronal pathways to social calculations.
Page 167.
As brain size increased in the past two million years, the size of hominin groups increased, too. Homo erectus was probably the first hominin species to live in groups that linked more than fifty individuals.
Page 167.
Cooking reduced the digestive work required of the gut, so the gut shrank (and, yes, there is fossil evidence for this), releasing some of the metabolic energy needed to run larger brains.
Page 168.
The oldest skull normally assigned to our species is almost two hundred thousand years old.
Page 169.
Without planning it, we have become a planet-changing species.
Page 170.
When we see human history as part of the larger history of the biosphere and the universe, the distinctive features of our species stand out more clearly.
Page 171.
Many different features make us the human package, from dextrous hands to large brains and sociability. But what makes us radically different is our collective control of information about our surroundings. We don’t just gather information, like other species. We seem to cultivate and domesticate it, as farmers cultivate crops. We generate and share more and more information and use it to tap larger and larger flows of energy and resources.
Page 171.
Human language crossed a subtle linguistic threshold that allowed utterly new types of communication. Above all, human languages let us share information about abstract entities or about things or possibilities that are not immediately present and may not even exist outside of our imagination.
Page 173.
Linguistic enhancements allowed humans to share information with such precision and clarity that knowledge began to accumulate form generation to generation.
Page 173.
Human language is powerful enough to act like a cultural ratchet, locking in the ideas of one generation and preserving them for the next generation, which can add to them in its turn. I call this mechanism collective learning. Collective learning is a new driver of change, and it can drive change as powerfully as natural selection. But because it allows instantaneous exchanges of information, it works mush faster.
Page 173.
Collective learning unleashed a bonanza of information about plants and animals, about soils, fire, and chemicals, and about literature, art, religion, and other humans.
Page 174.
Cultural evolution, a nonbiological mode of adaptation, acts in parallel with biological evolution as the means of transmitting knowledge of the past and adaptive behaviour across generations. All human accomplishments, from antiquity to modern times, are products of a sha4ed memory accumulated over centuries.
Page 175.
Human history begins … with collective learning. But when did collective learning begin?
Page 175.
Early evidence of ritual or symbolic or artistic activity is particularly significant because it suggests an ability to think symbolically or tell stories about imaginary beings, and that may indicate the arrival of modern forms of language.
Page 176.
There is an evolutionary mechanism known as competitive exclusion that explains whey two species can never share exactly the same niche. One will eventually drive out its rival if it can exploit the same niche slightly more effectively.
Page 176.
During the Pleistocene epoch, which encompasses the two million years since the evolution of Homo erectus, there were many ice ages. They normally lasted for one hundred thousand years or more, with briefer warm periods, or interglacials, between them. The period we live in now is a warm interglacial that began ten thousand years ago, at the start of the Holocene epoch.
Page 179.
Over thousands of years, small-scale migrations would eventually take our species, kilometer by kilometer, to every continent other than Antarctica.
Page 180.
One hundred thousand years ago, during the last interglacial, almost all humans lived in Africa, though a tiny number had left for the Middle East.
Page 180.
Twenty thousand years later, at the coldest phase of the last ice age, some Siberians trekked east across the land bridge of Beringia, which was crossable because so much water was locked up in poplar glaciers that ocean levels were lower than today. From Beringia, humans spread into the Americas, either by going through Alaska or by traveling in small boats along the northwestern coast of North America.
Page 181.
At present, the earliest firm evidence for the presence of humans in North America dates to about fifteen thousand years ago.
Page 181.
The English anthropologist Robin Dunbar has argued that 150 people represents the largest groups size that human brains can normally cope with, so it may be that communities naturally split if they got any larger.
Pages 181-182.
It makes sense to think of Paleolithic communities as families rather than societies.
Page 182.
Paleolithic societies were embedded in their surroundings ecologically and culturally in ways that modern urban dwellers struggle to understand.
Page 182.
In Australia, Siberia, and North America, the megafauna vanished not long after the arrival of humans.
Page 184.
Removing megafauna changed landscapes. Large herbivores can chomp their way through a lot of plants. Eliminating them increased the frequency of fires, as plant remains were left uneaten.
Page 184.
Humans used fire systematically to fertilize the land.
Page 184.
Systematic use of fire, not just to cook or protect yourself but to transform your environment, represents one of the first signs of the growing ecological power of our species.
Page 184.
Paleolithic science included knowledge about usable resources, whether hunted or gathered, whether for eating or making clothes or healing; knowledge about techniques, whether for navigation or hunting or digging for root crops; knowledge about astronomy; and social knowledge about how to approach and talk to elders or strangers and how to mark important transitions in the lies of individuals.
Page 185.
As humans spread, so did knowledge.
Page 186.
The Italian demographer Massimo Livi-Bacci estimates that thirty thousand years ago, there may have been five hundred thousand humans, and by the beginning of the Holocene, just ten thousand years ago, there may have been five or six million.
Page 186.
In the past ten thousand years, human lifeways were transformed by a cascade of innovations that we describe as farming or agriculture.
Page 188.
As farming societies grew, they supported much larger populations.
Pages 188-189.
More energy, resources, and people and more links between communities generated positive feedback cycles that accelerated change.
Page 189.
Farmers weeded and watered the land to help grow the plants they wanted, such as wheat and rice, and fenced in animals they valued, such as sheep and goats, but they removed weeds and shooed away or killed animals they didn’t like, such as snakes and rats. These activities changed entire landscapes, and plants and animals responded to these new environments, as they respond to all environmental changes, by adapting genetically, by evolving.
Page 190.
Farming was an energy and resource grab by a single, very resourceful species with access to increasing amounts of information about how to exploit its environment.
Page 191.
Symbiosis changes all species involved, as they coevolve.
Page 192.
Humans changed, too, but in different ways. Most of their adjustments were cultural rather than genetic.
Page 192.
Cultural change happens much faster than genetic change, and this explains why farming transformed human lifeways within just a few generations.
Page 193.
Farming spread around the world in less than ten thousand years, as farmers adjusted their farming methods to different species, soils, and climates.
Page 193.
Rising sea levels after the end of the last ice age severed links between Eurasia and the Americas, and there was hardly any communication between Eurasia and Australasia or with the islands of the western Pacific.
Page 193.
Farming, or near-farming, evolved quite independently in different parts of the world. It was not a one-off invention.
Page 195.
At the end of the last ice age, two worldwide changes coincided to create a small number of regions in which farming began to look tempting. First, climates began to get warmer and wetter around the globe; second, foragers now occupied so much of the Earth that some regions were beginning to feel overpopulated. Both changes nudged humans toward farming.
Pages 195-196.
Warmer, wetter climates and exceptional climatic stability made farming more viable than it had been for at least one hundred thousand years, providing the goldilocks conditions for the entire agrarian era.
Page 196.
In villages, having lots of children provided plenty of labor for the household as well as protection and care for the old. That’s why, in most sedentary communities, women were expected to bear as many children as they could, partly because they knew that perhaps half would die before they reached adulthood. Such attitudes sharpened differences in gender roles and ensured that most women’s lives would be dominated by the bearing and rearing of children throughout the agrarian era of human history.
Page 197.
As always with collective learning, the accumulation of new knowledge eclipsed ancient knowledge and insights.
Page 198.
We can be pretty sure that the first farmers took up farming reluctantly, because living standards seem to have declined in early agrarian villages.
Page 199.
Though famers could produce more food, they were also more likely to starve, because, unlike foragers, they relied on a small number of staple crops, and if those crops railed, they were in serious trouble.
Page 199.
Villages also produced refuse, which attracted vermin, and their populations were large enough to spread diseases that could not have survived in smaller, more nomadic foraging communities.
Page 199.
Foragers were attracted to regions liked the Fertile Crescent, areas that had plants and animals that were ripe for domestication.
Page 200.
From the Fertile Crescent, farming extended into Central Asia, Turkey, and then into the Balkans, Eastern Europe, and Western Europe between eight thousand and four thousand years ago.
Page 202.
Why farming increased so rapidly is not immediately obvious, because the farming life could be tough, and that’s why foragers survived, often alongside farmers, for many millennia.
Page 203.
As farmers spread, they transformed their surroundings. … By its very nature, farming requi4ed a manipulative attitude to the environment. While foragers normally thought of themselves as embedded within the biosphere, farmers saw the environment as something to be managed, cultivated, exploited, improved, and even conquered.
Page 203.
By modern standards, farming villages may look simple. But by Paleolithic standards, they were social, political, and cultural juggernauts.
Page 204.
The hugs, complex societies that have dominated the last five thousand years of human history appeared only after faring had spread far and fast enough to create a critical mass of people, resources, and new technologies.
Page 205.
Traditional rules of kinship were challenged as villages and networks of villages grew larger.
Page 206.
Everywhere, as farming spread, we begin to see new and more hierarchical structures that overlay village communities organized by traditional kinship rules.
Page 206.
Some innovations were game changers. Two particularly important innovations were the domestication of large animals and the emergence of large-scale irrigation.
Page 207.
Farming advanced by leaps and bounds in regions suitable for irrigation, including North India, China, Southeast Asia, and, eventually, some regions in the Americas.
Page 208.
Populations rose fast as farming methods improved and farming spread. It had taken at least one hundred thousand years for human populations to reach five million, at the end of the last ice age. By five thousand years ago, human numbers had quadrupled, rising to about twenty million. By two thousand years ago, there were two hundred million humans, forty times the number at the end of the last ice age.
Page 209.
Disease, famine, war, and death - the Four Horsemen of the Apocalypse - flourished in the agrarian era.
Page 209.
Farmers were also more vulnerable to famine than foragers were, because they relied on so few crops.
Page 209.
Agrarian civilizations were built on foundations created by the evolution of farming communities over several millennia, so we will treat their appearance not as an entirely new threshold but as a second phase of the threshold that gave us agriculture.
Page 211.
In foraging societies, the slow accumulation of knowledge encouraged migration into new environments rather than the accumulation of material goods. By contrast, farming societies to store goods, and in large quantities because many plants and animals were harvested over just a few weeks but eaten or processed over a year or more.
Page 212.
Surplus people, surplus food, surplus goods, and surplus energy represented new forms of wealth, which raised the question: Who was going to control (and enjoy) this wealth?
Page 212.
Surplus wealth meant surplus people. As productivity rose, not everyone needed to farm, so new social roles appeared.
Page 212.
The division of labor also created new forms of dependence.
Page 212.
Specialization encouraged new skills and techniques, so it was goth a measure and a driver of technological change.
Page 213.
Coppersmiths, goldsmiths, silversmiths, and blacksmiths all used technologies pioneered by professional potters.
Page 213.
In most agrarian civilizations it took about ten farmers to support one nonfarmer.
Page 214.
While farmers made up most of the population and provided most of society’s resources, specialists became increasingly important as societies became more interdependent.
Page 214.
Specialists provided the struts and bracing for agrarian civilizations.
Page 214.
As specialization increased, so did inequality.
Page 214.
When archaeologists find small children buried with great wealth, they can be sure that there are not just hierarchies but hierarchies that cross generations, because children could not have attained high status on their own.
Page 215.
The use of force to extract labor or produce or wealth became ubiquitous in agrarian civilizations. That is why slavery and forced labor were common in agrarian civilizations.
Page 216.
We have plenty of evidence that extortionate methods were used in all agrarian civilizations to maintain order and to extract labor and resources from the majority of the population.
Page 216.
Jericho, one of the oldest sites of continuous settlement anywhere in the world … because it had a well that never ran dry.
Page 217.
The diversity of skills, jobs, goods, and people found in cities explains why they became technological, commercial, and political dynamos in all agrarian civilizations and why they sucked people in from the surrounding countryside.
Page 217.
Away from the major population centers, the power of rulers depended on loose, hierarchical networks of local lords who often governed their own territories as more or less independent fiefdoms.
Page 218.
More complexity meant more information, and writing was the new technology that allowed the wealthy and powerful to keep track of the increasing resources and energy flows at their disposal.
Page 219.
Agriculture increased the resourced available to humans, so states could add one more trophic level at the top of the hierarchy.
Page 221.
Wealth never really consists of things; it consists of control over the energy flows that make, move, mine, and transform things. Wealth is a sort of compressed sunlight, just as matter is really congealed energy.
Page 221.
States, like farming, appeared independently in different parts of the world. Not surprisingly, they appeared where farming had already rflou4rished for centuries of millennia and was sufficiently developed to support large populations, large surpluses, networks of commerce and trade, and towns and cities.
Page 227.
We can trace the spread of agrarian civilizations within the different world zones almost as if we were watching the spread of an infectious disease.
Page 227.
The spread of states and civilizations stimulate new forms of collective learning as technologies, commodities, ideas, religions, and philosophies diffused over fast areas within the larger world zones. Page 229.
Roads were … the arteries of empires. Rulers build roads so their armies and merchants could move faster and farther, but they also established courier systems so that they could learn quickly of revolts or enemy threats.
Page 229.
Writing allowed rulers to store important information about their empires and their subjects.
Page 229.
From about three thousand years ago, furnaces were efficient enough to smelt iron, which was tougher than bronze and also cheaper, because iron ores were much more common and accessible than tin or copper ores.
Page 230.
The earliest states worshipped local deities, but as states expanded over larger areas, their gods, too, seemed to acquire greater powers and greater reach.
Page 230.
As states expanded, so, too, did networks of exchange. … these international exchange networks also carried goods no one wanted, including diseases such as smallpox and bubonic plague.
Page 231.
By two thousand years ago, humans were using seventy times the amount of energy they consumed at the end of the last ice age. This colossal energy bonanza from farming paid for population growth, for entropy’s complexity taxes, and finally for the wealth of the rich and powerful. There is little sign that it improved the lives of most humans.
Page 233.
All the evidence we have suggests that, though people surely enjoyed occasional luxuries, most of the time, most of them lived close to subsistence level throughout the agrarian era.
Page 234.
As human numbers increased, so did the pressure to find new land, new resources, new sources of wealth.
Page 237.
Europe lay at the western edge of the Eurasian landmass, far from the rich streams of commercial wealth that passed through the Mediterranean and Indian Oceans.
Page 240.
Globalization would transform the biosphere as much as it transformed human history.
Pages 240-241.
In the past, collective learning had worked at local or regional scales, which is why it took ten thousand years for farmers to spread around the planet. In a world of global networks, it took just a few centuries to transform much of Earth.
Page 241.
By the 1450s, Portuguese navigators had already established profitable maritime trades with the Mali Empire for the gold, cotton, ivory, and slaves that had previously been moved by camel caravan across the land routes of the Sahara.
Page 242.
Many, perhaps most, of the early encounters between people from the different world zones were violent, chaotic, and destructive. Suspicion of strangers played a role. But so did the many differences in population densities, technologies, patterns of social and military organization, and even resistance to diseases that had accumulated over many millennia.
Page 243.
The invention of efficient new ways of printing by Johannes Gutenberg in the mid-fifteenth century magnified the impact of new information flows. Almost thirteen million books were published between 1450 and 1500, and more than three hundred million between 1700 and 1750. Books, and the information they stored, ceased to be a rare, pricey luxury and became an everyday acquisition for people with education.
Page 245.
The tsunami of new information shook up education, science, and even religion throughout Europe, because this was the region through which new information flowed first and fastest.
Pages 245-246.
The idea of discovery is … a precondition for the invention of science. Study the world itself rather than what has been said about the would.
Page 246.
In Shakespeare’s time, even the most educated Europeans generally believed in magic and witchcraft, in werewolves and unicorns; they believed that Earth stood still and the heavens turned around it; that comets portended evil; that the shape of a plant advertised its medicinal powers because God had designed it to be interpretable; that was a true history.
Pages 246-247.
New information provided the intellectual bricks and mortar for new types of knowledge.
Page 247.
Rulers who borrowed from merchants were naturally eager to support commerce.
Page 248.
Though capitalism generated new forms of inequality, economists admired it because it was also good at generating both wealth and innovation.
Page 249.
The most important mega-innovations were usually those that released new flows of energy, such as fusion or photosynthesis. Farming counts as a mega-innovation because it let farmers tap larger shares of energy flows from rennet photosynthesis.
Page 251.
There were limits to the energy flows from farming, because it tapped only recently captured sunlight.
Page 251.
Like the activation energies that kick-start chemical reactions, energy from fossil fuels provided a pulse of energy that started the technological equivalent of a global chain reaction.
Page 254.
Cheap energy encouraged experimentation and investment in many new technologies. One of the most important was electricity.
Page 256.
Innovation, propelled by cheap energy, was the main driver of change. Innovations created steeper gradients of wealth and power that encouraged competition, which drove innovation, in a powerful feedback cycle.
Page 263.
Unlike the steam engine, whose heat source was external to the engine’s moving parts, in internal combustion engines, the het from fossil fuels drove pistons or rotors or turbine blades directly.
Page 264.
Albert Einstein developed his theory of relativity in the first two decades of the twentieth century. It improved on |Newton’s understanding of the universe by showing that matter and energy warped space and time, and this warping was the real source of gravity.
Page 265.
The noösphere, the sphere of mind, became a dominant driver of change within the biosphere.
Page 267.
Just as memory skills probably declined with the spread of writing, so calculating skills declined with the spread of computers and calculators.
Page 267.
Once, all humans had been foragers, and government really meant family relationships. After farming appeared, more and more people lived in peasant villages and supported themselves by farming. In farming societies, government meant, above all, mobilizing energy and resources from peasants. Today, move humans no longer gather or farm to produce their food and other necessities. They become wage earners. Like the potters of ancient Sumer, they live on wage ear4ners. Like the potters of ancient Sumer, they live on wages earned by doing specialized work. And that transformed the nature of government, because now governments had to become involved in the day-to-day live of all their citizens. This is because wage earners, unlike peasants, cannot survive without governments. ..… wage earners depend on the existence of laws, markets, employers, shops, and currencies. A specialist wage earner, like a nerve cell, cannot survive alone. This is why a world of wage earners is much more tightly integrated than a world of peasant farmers.
Page 268.
The governments of revolutionary France and the United States began to mobilize the loyalty of their subjects through democratization, which brought more of the population into the work of government, and through nationalism, which appealed to people’s sense of a shared national community.
Page 269.
The wars of the early twentieth century forced governments to intervene more actively in economic management.
Page 270.
Today, most farmers are entrepreneurs or wage earners. They work on huge industrial farms that specialize in just a few crops, some of them genetically engineered. They cultivate and transport their crops using lashings of fertilizers and pesticides and energy-hungry harvesters, tractors, and trucks. Modern farmers grow crops not to eat but to sell. They manage businesses. They borrow money form banks and buy their sees, fertilizers, and tractors from large corporations.
Page 271.
As different jobs and skills and forms of expertise proliferate, people spend more and more time learning. Information - expert knowledge - is what counts, rather than the generalized skills of peasants.
Page 271.
Despite the wars of the twentieth century, interpersonal relations have also become, for the most part, less violent. There is a clear logic to this change, as coercion has become a less effective way of controlling behavior in the last century or two.
Page 272.
Personal violence is still all too common, but, relative to the number of people in the world, it is much rarer than it used to be and no longer regarded in most of the world as an acceptable way of controlling behavior.
Page 272.
The idea of progress, which most of us take for granted, is also new. For the majority of human history, people assumed that, barring catastrophes, children would live much as their parents had.
Pages 272-273.
The fall in fertility rates after the earlier fall in mortality rates is what demographers call the demographic transition: the emergence of a new demographic regime of low fertility and low mortality.
Page 273.
Reduced pressure on women to spend their entire adult lives bearing or rearing children blurred traditional divisions between male and female roles and allowed women to take up roles form which they had been excluded during most of the agrarian era.
Page 273.
The activities of humans are changing the distribution and number of living organisms, altering the chemistry of the oceans and the atmosphere, rearranging landscapes and rives, and unbalancing the ancient chemical cycles that circulate nitrogen, carbon, oxygen and phosphorous through the biosphere.
Page 274.
In the two centuries since the industrial revolution, levels of atmospheric carbon dioxide had risen to levels higher than any seen for almost a million years.
Page 275.
Rising carbon dioxide levels will mean warmer climates, and warmer climates will mean more energetic hurricanes, storms, and wind currents and rising ocean levels that will flood low-lying cities. The effects will persist for many generations because, once released into the atmosphere, carbon dioxide stays there for a long time.
Page 275.
Levels of methane have risen even faster in the past two centuries, driven largely by the spread of rice-growing in flooded fields and the increasing number of domestic livestock. Ethane is an even more powerful greenhouse gas, tough it breaks down faster.
Page 275.
Most species of animals and plants that are not of immediate value to humans are declining in numbers.
Page 277.
The fossil-fuels revolution has magnified the scale of human impacts.
Page 277.
New flows of information and energy have woven humans, and plants, as well as the of the earth, seas, and atmosphere, into a single system constructed primarily for the benefit of our own species.
Page 278.
Rapid population growth depended on huge increases in the energy available to our species.
Page 278.
Paradoxically, increasing wealth also means increasing inequality, and even as the numbers living above subsistence are rising, the numbers living in extreme poverty remain higher than ever before in human history.
Page 280.
In the early twenty-first century, inequality seems to be on the rise, and the huge number of people alive now means that, in absolute terms, there are far more people living n extreme poverty today than there were in the past.
Page 281.
For most of human history, life expectancies at birth were less than thirty years. This was not because people didn’t live into their sixties and seventies but because so many children died young and so many adults died of traumas and infections that would not have killed them today.
Page 281.
Though it is tempting to think that the modern world has abolished slavery, the 2016 Global slavery Index estimated that more than forty-five million humans today are living as slaves.
Page 282.
The flows of energy and resources that support increasing human consumption are now so huge that they are impoverishing other species and jeopardizing the ecological foundations on which modern society is built.
Page 282.
Few modern educational systems spend much time teaching systematically about the future.
Page 287.
As quantum physics has shown, at the smallest scales, the universe is not deterministic. Unexpected things do happen and, like the flapping of a butterfly’s wings, they can cascade through causal chains with sufficient power to send the future off in many possible directions.
Page 289.
Is it, perhaps, the fate of all species capable of collective learning to hit a wall of complexity, at which point their societies collapse? Is that why we have not yet contacted any other species capable of collective learning?
Page 290.
Alertness, determination, and hope - these are the crucial virtues of anyone on a quest, because the journeyer who misses opportunities or who gives up too soon or who despairs must fail.
Page 291.
Activation energies provide the initial kick that gets vital chemical reactions going but once they are under way, less energy is needed.
Page 294.
The turbulent dynamism of recent centuries is typical of all periods of creative destruction. … once the violent energies of creation have done their work, we expect a new and more stable dynamism, as something new takes its seat in the universe.
Page 294.
How resilient is the biosphere, after all? We don’t really know.
Page 296.
The world’s economies will wean themselves off fossil fuels sometime later in this century.
Page 298.
Governments are national and they are competitive, which means that the wealth and power of each individual nation tends to loom larger in political calculations than the needs of the world as a whole. Most governments are also tied to short-term goals by the methods by which officials are chosen or elected.
Page 299.
In a capitalist world, most enterprises are governed by need to make profits, and at present profit-making all too often points in dirre4ent directions from the quest for sustainability.
Page 300.
Today, in a more complex world, the behavior of governments will depend, in part, on the existence of voters who take the quest seriously.
Page 300.
We can track the movements of tectonic plates, so we can guess roughly where the continents will be in one hundred million years. At present, it looks as if continental plates will regather in a new supercontinent that has already been dubbed Amasia because it will join Asia and the Americas.
Page 303.
The future of the universe seems to depend on a small number of variables. The critical ones are the rate of expansion and the amount of matter/energy in the universe.
Page 304.
Since it was discovered int eh late 1990s that the rate of expansion is increasing, it seems there must exist some kind of dark energy that is powerful enough to override the gravitational pull of all the mass and energy in the universe. That suggests that the universe will keep expanding forever and will do so faster and faster and faster.
Page 304.
It will turn out that everything that seemed permanent in our universe was actually ephemeral.
Page 305.