Origin Story: A Big History of Everything

by David Christian

The conventional diagram of the London Underground ignores most of the twists and turns, but it still helps millions of travelers get around the city. This book offers a sort of London Underground map of the universe.

Stephen Hawking argues that the question of beginnings is just badly put. If the geometry of space-time is spherical, like the surface of Earth but in more dimensions, then asking what existed before the universe is like looking for a starting point on the surface of a tennis ball. That’s not how it works. There is no edge or beginning to time, just as there is no edge to the surface of Earth.

Frankly, today we have no better answers to the problem of ultimate beginnings than any earlier human society had. Bootstrapping a universe still looks like a logical and metaphysical paradox. We don’t know what Goldilocks conditions allowed a universe to emerge, and we still can’t explain it any better than novelist Terry Pratchett did when he wrote, “The current state of knowledge can be summarized thus: In the beginning, there was nothing, which exploded.”

Today, the evidence that our universe began in a big bang is overwhelming. Lots of details remain to be worked out, but for the time being, the core idea is firmly established as the first chapter of a modern origin story. That’s the bootstrap. And, as quantum physics allows things to appear from a vacuum, it seems that the entire universe really did pop out of a sort of nothingness full of potential.

We now know that there are many simple molecules in galactic dust clouds, and they include some, such as amino acids (the building blocks of proteins), that are crucial for life on Earth.

Two processes turned a spinning disk of matter into planets, moons, and asteroids. The first was a type of chemical sorting. Violent bursts of charged particles from the young sun, known as the solar wind, blasted lighter elements, such as hydrogen and helium, away from the inner orbits to create two distinct regions. The outer regions of the young solar system, like most of the universe, consisted mainly of the primordial elements, hydrogen and helium. But the inner regions, where the rocky planets—Mercury, Venus, Earth, and Mars—would form, lost so much hydrogen and helium that they had a rare chemical diversity. Oxygen, silicon, aluminum, and iron make up over 80 percent of Earth’s crust, with elements such as calcium, carbon, and phosphorus playing lesser roles. On Earth, hydrogen plays only a medium-size role, and helium is hardly ever sighted.

Despite what Hollywood might have us believe, we cannot dig deep into Earth. The deepest dig so far is about twelve kilometers, which is about 0.2 percent of the distance to Earth’s core. That hole was drilled in the Kola Peninsula in the far northwest of Russia as part of a geological investigation.

Entropy is rubbing its hands at the thought of the energy taxes and fees it can levy as complexity and information increase.7 Indeed, some have argued that entropy actually likes the idea of life (and may encourage it to appear in many parts of the universe), because life degrades free energy so much more efficiently than nonlife.

Since then, we have learned that many of these molecules can form even in the less chemistry-friendly environments of interstellar space, so lots of simple organic molecules may have arrived on Earth, ready-made, inside comets or asteroids. For example, the Murchison meteorite, which fell to Earth near Murchison, Australia, in 1969, contained amino acids and several of the chemical bases that we find in DNA. Such meteorites were much more common early in Earth’s history than they are today, which suggests that the early Earth was already seeded with many of the raw materials of life and quite capable of manufacturing more.

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.

Respiration gives you the energy of fire without its destructiveness.

So much could have gone wrong. A supernova in a neighboring star system could have blown up. Or we could have collided fatally with another planet. 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. And big life really is big. We are to bacteria what Dubai’s 830-meter-tall Burj Khalifa is to an ant crawling past the doorman’s shoes.

Since about 370 million years ago, oxygen levels have mostly remained between 17 percent and 30 percent of the atmosphere.11 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.

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. They fixed huge amounts of carbon through photosynthesis, so as the Earth turned green, carbon dioxide levels fell to perhaps a tenth of earlier levels.12 The impact of the first forests was particularly significant because as yet, there were no organisms that could break down the lignin in wood. That’s why forests from the Carboniferous period (from 360 to 300 million years ago) were mostly buried beneath the soil, along with the carbon they had drawn down from the atmosphere. Over time, they fossilized to form the coal seams that later powered the industrial revolution.

Carboniferous forests may have doubled rates of photosynthesis, and that effectively doubled the biosphere’s total energy budget, allowing the production of many more organisms.

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 do.

When the asteroid hit, it was moving at thirty kilometers a second (about one hundred thousand kilometers an hour), having taken just seconds to fly through Earth’s atmosphere. We know exactly where it fell: in the Chicxulub (pronounced “Chikshulub”) crater in the Yucatán Peninsula of modern Mexico. The asteroid evaporated as it punched through the crust, leaving a crater almost two hundred kilometers across. Molten rocks were hurled into the air, where they formed dust clouds that blocked sunlight for many months. Limestone evaporated, spraying carbon dioxide into the atmosphere. An area hundreds of kilometers around the impact point was stripped of life. Hundreds of kilometers beyond that zone, forests lit up in massive firestorms. At sea, a tsunami formed a wall of water that crashed down on the shores of the Gulf of Mexico and killed fish and dinosaurs hundreds of kilometers away. 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.

There was one more crisis to be survived before mammals could take over the Earth. That was the Paleocene-Eocene thermal maximum (PETM, for lovers of acronyms), a short, sharp shock of greenhouse warming at the border between the Paleocene and Eocene epochs, about fifty-six million years ago. It was damaging enough to drive many species to extinction. The PETM is of interest today because it is the most recent period of rapid greenhouse warming in Earth’s history, so it may help us understand climate change today. The parallels are eerie. The amounts of carbon dioxide released into the atmosphere during the PETM were similar to those being released today by the burning of fossil fuels, and fifty-six million years ago, the result was an increase of between five and nine degrees Celsius in average global temperatures.

Culturally, we humans are astonishingly diverse, and that is part of our power. Genetically, though, we are more homogenous than our closest living relatives, the chimps, gorillas, and orangutans. We just haven’t been around long enough to diversify much. Besides, we are extraordinarily sociable, and we love to travel, so human genes have moved pretty freely from group to group.

Primates are exceptionally brainy. Their brains are unusually large relative to their bodies, and the top front layer of the brain, the neocortex, is gigantic. In most mammal species, the cortex accounts for between 10 percent and 40 percent of brain size. In primates, it accounts for more than 50 percent, and in humans for as much as 80 percent.

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.

But in 1968, two geneticists, Vincent Sarich and Allan Wilson, showed that we could estimate when two species diverged by comparing the DNA of species that are alive today. This is because large stretches of DNA, particularly those parts that do not code for genes, change randomly and at a relatively consistent pace. Genetic comparisons using these insights showed that humans, chimps, and gorillas shared a common ancestor until about eight million years ago, at which point the ancestors of modern gorillas decided to go their merry way. Humans and chimps shared a common ancestor up to about six or seven million years ago. In other words, somewhere in Africa six or seven million years ago, there existed a creature from which modern humans and chimpanzees are both descended. We do not yet have fossil remains of this creature, but modern genetics tells us it was really there.

The favored species on which farmers lavished so much care and work (the domesticates) gained little in quality of life. But they did well demographically. Their numbers soared, while the number of wild animals (the animals farmers were not interested in) plummeted. In the year 2000, the total biomass of all wild land mammals was about one-twenty-fourth that of domesticated land mammals.

However, in villages, infants no longer had to be carried and they could eventually be put to work. That changed attitudes to families, to children, and to gender roles. 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.

The human remains reveal how tough life could be for the first farmers. All have heavily worn teeth from a diet dominated by grains, though tooth wear diminishes with the appearance of pottery, which made it possible to process grains into gruels. Women’s bones show clear evidence of wear from long hours of rocking back and forth on their knees as they ground grain.

potters needed furnaces to fire their pots, and over time they built more efficient furnaces that operated at higher temperatures and yielded better finishes. But better furnaces were just what was needed to separate copper, tin, or iron from the ores in which they were embedded so the metals could be molded, bent, or hammered into household goods, ornaments, and weapons. Coppersmiths, goldsmiths, silversmiths, and blacksmiths all used technologies pioneered by professional potters.

European navigators found new continents and islands, saw new constellations in the southern skies, and encountered peoples, religions, states, plants, and animals never mentioned in ancient texts. 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. That information forced European scholars to question ancient science, and even the Bible. It began to undermine traditional origin stories. In sixteenth-century England, Francis Bacon argued that science and philosophy should no longer rely mainly on ancient texts but should actively seek out new knowledge, like Europe’s navigators: “By the distant voyages and travels which have become frequent in our times many things in nature have been laid open and discovered which may let in new light upon philosophy.”6 “There is,” wrote Joseph Glanvill in 1661, “an America of secrets, and [an] unknown Peru of Nature” waiting to be found.

The steep gradients of wealth and information in the first global-exchange networks opened such vast commercial opportunities for European merchants and entrepreneurs that their wealth and political influence increased until even emperors, such as the Holy Roman emperor Charles V, began to borrow from merchants. European rulers were generally keener to work with merchants than traditional rulers such as the Ming emperors of China had been because most European states had modest resources, fought endless wars, and were constantly short of cash. And rulers who borrowed from merchants were naturally eager to support commerce. In this way, there emerged a close symbiotic relationship between European traders and rulers. Rulers protected and supported commerce, and in return they got the right to tax and profit from commercial wealth. This was the earliest and crudest form of capitalism, a system admired by European economists from Adam Smith to Karl Marx.

To get a sense of the energies locked up in fossil fuels, imagine carrying a car full of passengers over your head and running very, very fast for several hours, then remind yourself that a few gallons of gasoline pack that much energy and more (because a lot of the energy is wasted).

By the middle of the nineteenth century, England produced a fifth of global GDP (gross domestic product) and about half of global fossil-fuel emissions. Not surprisingly, global levels of atmospheric carbon dioxide began to rise from about the middle of the nineteenth century. And as early as 1896, the Swedish chemist Svante Arrhenius recognized both that carbon dioxide was a greenhouse gas and that it was being generated in large enough amounts to start changing global climates.

There were many powerful feedback loops. Improved steam engines allowed access to deeper mines, which lowered the cost of extracting coal, so the amount of coal that was mined increased by fifty-five times between 1800 and 1900. Cheaper coal made steam engines more economical, while steamships and locomotives slashed the cost of transporting cattle, coal, produce, and people by land and sea, which stimulated global trade. Railways increased demand for iron and steel, and innovations in steel production made it economical for the first time to use steel in mass-produced goods such as tin cans, a new way of storing and preserving foodstuffs. There were unexpected side effects. Using steam to spin and weave textiles increased the demand for raw cotton, which stimulated cotton planting in the United States, Central Asia, and Egypt. Industrial production of textiles increased demand for subsidiary products such as artificial dyes and bleaches, which kick-started the modern chemicals industry, many of whose products came from coal.

Total energy consumption doubled in the nineteenth century and then rose by ten times in the twentieth century. Human consumption of energy rose much faster than human populations.

In 1890, human impacts on the nitrogen cycle were insignificant. Each year, humans extracted about fifteen megatons of nitrogen from the atmosphere, mainly through farming, while wild plants extracted about one hundred megatons, or almost seven times as much. One hundred years later, humans and plants had swapped roles. By 1990, the area of farmed land had increased to such a degree that wild plants were extracting only about 89 megatons, while human extraction of nitrogen through farming and fertilizer production had risen to 118 megatons. Our impact on other large mammals has also been profound. In 1900, wild land mammals accounted for the equivalent of about ten megatons of carbon biomass. Humans already accounted for about thirteen megatons, while domesticated mammals—our cows, horses, sheep, and goats—accounted for an astonishing thirty-five megatons. In the next century, these ratios would get even more warped. By 2000, the total biomass of wild land mammals had fallen to about 5 megatons, while that of humans had increased fast (not surprising, given what we know of population growth) to about 55 megatons and that of domesticated mammals to an astonishing 129 megatons. This is a powerful indicator of the extent to which expanding human activities have squeezed out other species of large animals by taking more and more of the biosphere’s resources. The point is a general one. Most species of animals and plants that are not of immediate value to humans are declining i...