Book Summary: “The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis” by Ruth DeFries


Title: The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis
Author: Ruth DeFries
Scope: 4 stars
Readability: 4 stars
My personal rating: 5 stars
See more on my book rating system.

If you enjoy this summary, please support the author by buying the book.

Topic of Book

DeFries traces human history with a particular focus on food production.

My Comments

While many people today are convinced that we have entered a time period when natural limits (particularly global warming) put hard constraints on progress, DeFries reminds us that human history is full of examples of innovations overcoming perceived limits.

Key Take-aways

  • Food is the ultimate energy source for all human endeavors. Without food, no other achievements are possible.
  • Humans required:
    • A planet that was in the Habitable Zone: the correct distance from the Sun for liquid water.
    • Plate tectonics which naturally recycle carbon and other organic elements.
    • An abundance of plants and animals that can be manipulated for the benefit of our species
  • The biggest problem for traditional societies was to transform energy from the sun into a form that people can eat.
  • Humanity has repeatedly overcome natural limits to food production by innovating new agricultural technologies and techniques:
    • Use of animal-driven plows.
    • Medieval three-field system
    • Norfolk four-field system
    • Guano and nitrates
    • Justus von Liebig’s mineral theory
    • Haber-Bosch process to create synthetic nitrogen fertilizer.
    • Hybrid corn
    • Pesticides
    • Genetic engineering of crops

Important Quotes from Book

This book is an attempt to reconstruct how we became extraordinary, how human civilization evolved to manipulate nature so much that most people live in cities. Our journey began by living off the plants and animals that nature made available. Now we are the only species with most of its members subsisting on food produced in some distant location.

Humanity’s unmistakable imprint on the planet typically evokes one of two antagonistic reactions. In one, the Earth’s dramatic transformation is proof that human ingenuity can trump any barriers nature presents. Every problem has a technological solution.

The counterargument views our enormous imprint as the height of folly and proof that humanity is headed toward disaster.

A broader and longer-term perspective reveals a species that, like any other, manipulates its surroundings to expand its territory and grow in numbers. The difference is the extraordinary ability of our species to twist food from nature… A broader perspective views human civilization as neither right nor wrong, neither good nor bad, but as part of the evolution of life on this planet.

This book traces humanity’s remarkable journey from an ordinary mammal to a world-dominating, urban-dwelling species. Striking patterns emerge from this long-term view. One is that we have always lived off of the food that we have managed to squeeze from our surroundings, just like any other species, from the smallest microbe to the largest carnivore. Another is that civilization’s attempts to extract food from nature are experiments. Through trial and error, we have found new ways to extract more food with less work. Our capacity to build knowledge across generations, a hallmark of our species, has allowed one experiment to build on the last in a never-ending progression. If one experiment fails, we lurch, stumble, and try some other path. Even today’s massive manipulation of nature to feed billions is simply one more experiment in a long chain.

The process goes something like this. It starts with a hungry person in search of the easiest and quickest way to get a meal. At some point, a way to manipulate nature emerges, perhaps when someone tames an edible plant or devises a way to spread scarce nutrients so crops can grow.

With more food to go around, the success ratchets up the number of our species, and people expand into new places. Inevitably, any innovation reaches its limit, creating demands it cannot satisfy, generating too much pollution, or creating some other unforeseen obstacle. Once again, specters of not enough food to go around appear, and prospects look grim. The hatchet falls. Then a new pivot, a new way to use nature’s endowments, emerges. The ratchet turns again, providing more and more people with food, committing civilization to keeping the growing number of people fed. At some point there’s an even bigger hurdle, perhaps from the sheer number of people or from disease, drought, or some other calamity. Ratchet, hatchet, pivot; ratchet, hatchet, pivot. In every cycle, the stakes get higher, as our species expands in numbers and in the extent of its reach across the world. In every cycle, new obstacles emerge. And in every cycle, millennium after millennium, humanity as a whole has muddled through.

Those cycles continue today, but in a different guise. For most of human history the hatchets were famine and shortage. As we will see in later chapters, our current problems are more about abundance than about lack of food.

We have lived through the Big Ratchet—the extraordinary second half of the twentieth century—when our twists of nature sped up so fast that the trajectory of human civilization changed course.

But now, at the Big Ratchet’s crest, most of us live in cities and consume food that is produced far away by a minority of the human population. This change makes us unique.

Our species passed this milestone in May 2007. After that fateful date, more than half of us have lived in cities… itself. The shift is as fundamental as our transition from forager to farmer more than 10,000 years ago.

Food is the ultimate energy source for every human endeavor. It is more essential than coal, gas, or any of the other sources that power our machines. Without food, there can be no cities, trade, cuisines, language, great artwork, symphonies, novels, theater, or any of the other hallmarks that set our species apart from others.

But without a planet that can provide nourishment and habitat for a wide variety of plant and animal species, even the most intelligent life forms could not manipulate nature to produce food on such a grand scale. A confluence of fundamental features collectively forms the foundation for life on our planet. The Earth has the right location in the solar system, an internal magnet, the machinery necessary for regulating greenhouse gases and recycling nutrients, and, above all, a long enough period of time with a stable enough climate to support varied forms of life as they evolved. Together, these features satisfy three fundamental requirements for a planet that can support an ingenious species such as ours: a stable climate, a planetary recycling apparatus, and a smorgasbord of life. These features were present on Earth long before humans walked on the planet, and they will likely be present long after humans have left the scene.

For a planet, location, as for real estate, is the first crucial feature. Distance from the sun is paramount. This distance dictates whether liquid water—the solvent in which life emerged on Earth and the substance that sustains life—is present.

A planet where life can evolve must be not just in the Habitable Zone, but in the Continuously Habitable Zone, the zone that remains habitable over a long enough time for complex animal life to evolve. Our planet has been in the Continuously Habitable Zone for some 5 billion years, and it will remain there for a billion more.

The regulatory machinery that makes it possible for a planet to recycle water, carbon, and much more is the truly distinguishing feature of our planet. More than anything else, it has saved the planet from the scorching fate of Venus and the frozen fate of Mars. It has kept nutrients for plants and animals cycling from land to ocean to deep beneath the surface to the atmosphere and back. It is the most precious, and the least appreciated, foundation for human civilization.

The slow movement of dozens of plates that carry continents across the Earth’s surface and give rise to mountains powers carbon’s recycling machinery. The churning of the Earth’s mantle, driven by the planet’s internal heat, underlies the plates’ movements. Plate tectonics does not exist on either Venus or Mars.

The extraordinary, life-enabling feature of this cycle is that it operates

faster or slower depending on the temperature. When times are hot, the acid-producing chemical reactions speed up, eroding more rock. This is what happened during the warm reign of the dinosaurs about 65 million years ago. With faster reactions, more carbon dioxide gets pulled from the atmosphere, and temperatures cool. When times are cool, the process slows down, more carbon dioxide accumulates in the atmosphere, and temperatures warm. The self-correcting cycle oscillates between what geologists call hot houses—times of fervent volcanic activity—and ice houses—times when weathering outpaces volcanoes. Over time scales of millions of years, weathering serves as a thermostat to regulate our planet’s climate. The thermostat prevents a runaway greenhouse like Venus or a frozen state like Mars.

As far as we know, ours is the only planet with the machinery for recycling nutrients from plants to animals and to soil, rocks, and the air and back again to plants.

Both nitrogen and phosphorus have their own distinct life-enabling recycling machinery. But the two cycles are alike in one key respect: the pace at which they operate has constrained humanity’s ability to feed itself for nearly all of human history.

But there is a third requirement for the success of a species like Homo sapiens: an abundance of plants and animals that can be manipulated for the benefit of our species.

In essence, a series of ratchets, hatchets, and pivots over geologic time guided a lifeless planet to one with staggering diversity. And each time, the complexity ratcheted up a notch.

The first pivot occurred around 3.5 billion years ago, when self-replicating single-celled organisms arose from the primordial stew of the building blocks and the precursors for life.

The next pivot brought another layer of complexity and the most consequential ratchet for the diversity of life: Photosynthesis

Communication. Sharing information. Transmitting knowledge. These tools constitute the lifeblood of all cultures and the foundation for all life. When ancient forms of life acquired the machinery to store DNA and pass their genes to their offspring, they secured a means to transmit information to the next generation about how to survive in the environment.

In cumulative learning, skills are not just passed from one generation to the next and between peers, but generations can improve or modify the skills and pass on the improved versions. Innovations can build up more quickly in cumulative learning than in hard-wired natural selection; trial-and-error learning, which restarts with each generation; or social learning that does not spread beyond a few peers.  

Humans have taken cumulative learning to a level unprecedented in other species. As a result, our species is agile, adaptable, and capable of the ingenuity it has used to dominate the world.

Nitrogen gas is the most abundant of all gases in the atmosphere. For each scoop of air, about eight out of ten parts are nitrogen gas. The irony is that nitrogen is of no use to plants or animals in its atmospheric form. Nitrogen in the atmosphere is a gas, with two nitrogen atoms bound to each other. The bond is among the tightest found in nature. Unless the bond is broken apart, the nitrogen is simply inert gas. Plants can only make good use of nitrogen in a different chemical form. Most plants need nitrate, a compound of a single nitrogen atom bound to three oxygen atoms, to do the job. Unlike nitrogen gas, nitrate can dissolve in water in the spaces between soil particles, so that plants can slurp up the nitrogen through their roots.

Consider Justus von Liebig’s brilliant Law of the Minimum. Lack of a single nutrient, he said, keeps a crop from thriving, even if other nutrients are plentiful. And here Liebig was onto something: once nitrogen is sufficient, the next nutrient to be in short supply is likely to be phosphorus. The two go in lockstep.

Like nitrogen, phosphorus is a basic building block for all forms of life. Plants need phosphorus in their cells to transfer energy for photosynthesis. In animals, the nutrient is critical for bones and teeth. In cells, it transfers energy in the food we eat into a form usable for growth and movement. Also, as with nitrogen, humans and other animals can only obtain phosphorus by eating plants that contain it or by eating animals that have eaten phosphorus-containing plants.

Phosphorus’s slow journey presents a challenge for human ingenuity: how to break into the cycle and speed it up. And we have, indeed, found two basic ways to do this: we can keep the phosphorus in manure and dead plants and animals cycling in a short-term loop, or we can dig up the phosphorus and move it to a place of our own choosing.

The problem for humanity is not a shortage of energy from sunlight. The problem is getting the sun’s energy into a form that people can eat. There are plenty of plants, but most are too woody or leafy to digest. It’s a lot of work to channel the sun’s energy to the plants and animals that we can eat.

So long as the animals can get enough calories to eat and are tame enough to do the work, it’s a way out of the energy conundrum.

The Black Death killed a third of Europe’s population and demolished the economy… The centuries-long pivot that followed that devastating time relied on animals for labor and manure and clover for its nitrogen-fixing magic. The system at the time had been to rotate crops and fallow in a three-year sequence. One year, a farmer would plant his field with a winter cereal such as wheat, barley, or rye. The next year, he would switch to a spring cereal, such as oats, peas, or beans. In the third year, he would allow grass to grow back as fodder for animals. Manure from livestock grazing on the grass replaced the nitrogen lost from the soil in the cereal crops. In this system, a third of the fields were fallow at any given time.

A major break from the pattern came with the famous Norfolk four-course system of the mid-eighteenth century. The critical element was clover, introduced to England from the Netherlands. Nitrogen-fixing clover could replace the grass fallow. The Norfolk system, named for the English county where the system was first developed, rotated plots on a four-year cycle of winter wheat, turnips, barley, and clover. Clover meant more fodder and nitrogen-enriched soils. Turnips meant more winter feed for livestock, more meat, and more manure.

At an 1840 meeting of the British Association for the Advancement of Science in Glasgow, Justus von Liebig had proclaimed a civilization-changing theory. The “humus theory” that had previously prevailed purported that plants lived off extracts derived from organic matter, such as manure, and that a plant’s internal vital force generated other critical constituents. Liebig’s opposing “mineral theory” countered that plants could get their nutrients as readily from salts and rocks as from farmyard manure and night-soil.

By the century’s end, the mineral theory was firmly established as a basis to produce chemical fertilizers on a commercial scale.

This discovery promised to usher in a new era of agriculture. No longer would humanity’s food supply be tethered to manure, guano, or human waste. Here was a titanic pivot that could change the course of civilization.

Haber’s invention to industrially fix nitrogen pivoted humanity into a new era in the twentieth century.

The Haber-Bosch process became a mainstay of American agriculture after World War II. Production of nitrogen fertilizers, whether from repurposed, war-era factories or new ones built for the purpose, mushroomed more than eightfold in the second half of the century.

The total amount of food produced in the industrialized world skyrocketed with the invention. But that’s not all: Haber-Bosch also transformed what people ate. More grain meant more animals at the trough, which meant more people enjoying meat, eggs, and dairy more often. Four out of ten people alive at the beginning of the third millennium were subsisting on foods that farmers would not have been able to produce without fertilizer made with the Haber-Bosch process, including grains to feed meat- and dairy-producing animals. There is no mistaking that the Haber-Bosch process was one of humanity’s all-time pivot points, changing diets and ratcheting up the number of mouths that the world’s supply of food could feed.

Today, the industrial process fixes more nitrogen from the air than the natural processes of soil microbes and lightning could ever accomplish. In essence, Haber opened the faucet for nitrogen to flow from the air to the living world.

Just as Haber-Bosch had replaced the saltpeter trade, so phosphate rocks replaced bone.

By the beginning of the twentieth century, human ingenuity had essentially dismantled the natural phosphorus cycle. Phosphorus in ancient rocks was replacing the nutrients lost with each harvest.

The Belgian engineer Jean J. Lenoir took not a small step, but a big leap. His mid-nineteenth-century internal combustion engine ushered in gasoline-powered tractors in the early part of the twentieth century. These proved vastly more practical than the steam-engine tractor.

Fuel to propel heavy machinery didn’t just add massively to the energy available from human and animal power on the farm. It also powered machines to build dams that could store water and quench a crop’s thirst where rainfall was too scarce.

In 1926, future US vice president Henry Wallace founded Hi-Bred Corn Company in Iowa, the first to sell hybrid seeds to farmers. Hybrid seeds took off like wildfire throughout the Corn Belt, encouraged by New Deal programs during the Great Depression. Yields were phenomenal. By the mid-1940s, all of the corn planted in Iowa was from hybrid seed. By the mid-1950s, hybrids were planted on nine out of ten acres of corn in the United States. By 1960, corn yields had nearly doubled from the early decades of the century when blowing pollen had fertilized crops. Ultimately, about half the staggering explosion in corn yields in the twentieth century could be traced to hybrid seeds. The other half of the growth came from the use of chemical fertilizers, pesticides, and new machinery.

At the end of the nineteenth century, the US Department of Agriculture had formalized the acquisition of plant specimens through an Office of Foreign Seed and Plant Introductions. A few decades later, two scientists on the staff, Howard Morse and Bill Dorset, packed up their families and took off on a soybean-collecting odyssey. Between 1929 and 1931, they traveled throughout China, Japan, and Korea. From fruit and vegetable markets, food and flower shops, botanical gardens, farms, factories that made food from soy, and the wild, they brought back more than 10,000 specimens of soybeans.

In 1922, entrepreneur Augustus Staley, of Decatur, Illinois, had seen the commercial potential in the crop. He paid Illinois farmers to grow soybeans and built the first factory to process the harvest. The profitable products turned out not to be soy sauce, tempeh, and tofu, but oil crushed from the bean, and soymeal to feed cows, chickens, and pigs. The crop made the company’s fortune and over time made Decatur the soybean capital of the world.

The prairies and flat expanses of fertile soil went on to become one of the world’s main centers for industrial agriculture. When the century started, almost every farm in the country was multifunctional, growing vegetables, harvesting fruit trees, and raising chickens, horses, dairy cows, and pigs, all at the same time. As the century progressed, small farms amalgamated into larger ventures. The large farms became more specialized, growing only a handful of crops, most often including corn, wheat, or soy. And as new machinery arrived to do the jobs of the laborers, only a small fraction of the population remained to work the large farms. Most of the rural population moved to the cities.  

Of all the people whose ideas of and innovations sent the world hurtling toward the post–World War II explosion in what and how much people eat, one name stands out: Norman Borlaug, the plant breeder from the American Midwest who countered Rachel Carson’s criticisms of chemical pesticides. Some revere Borlaug as a humanitarian saint. Others revile him for the enormous changes he ushered in throughout the developing world.

Where the Green Revolution had taken hold, tractors were replacing water buffaloes in the fields, and herbicides were replacing people who pulled weeds out by hand. As in North America earlier in the century, people were leaving the countryside and moving to the cities for jobs in factories and offices. Three out of every ten people lived in cities in 1950.

This was the Big Ratchet: In the second half of the twentieth century, all the twists of nature—nourishing the soil, extracting energy from the ancient sun, warding off unwanted pests and manipulating genes— built on each other. Just as the pivot to chemical fertilizers would not have been possible without coal for factories and oil for machinery, the genetic twists to breed dwarf plants and vigorous hybrid seeds would not have been possible without chemical fertilizers and irrigated fields. Without the genetic twists, in turn, yields would not have soared around the world. The Big Ratchet’s abundance of rice, wheat, and corn—the staples of modern civilization—helped set the stage for the remarkable times in which we now live. In the long arc of the history of human civilization, our times rival the Earth-changing transition from forager to farmer. This time, the pivotal transition is from farmer to urbanite.  

If you would like to learn more about how humans have solved problems throughout their history, read my book From Poverty to Progress.

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