The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis (6 page)

Geologists did not always appreciate the dynamism and cycling in nature. The prevailing view in the 1700s was that floods dumped rocks
on the surface. The much-maligned Scottish gentleman farmer, naturalist, and geologist James Hutton argued that soils, rocks, and mountains were destroyed and created in a perpetual cycle. “We find no vestige of a beginning—no prospect of an end,” he wrote. These words were as true in the 1700s as they were for the previous millions of years and as they will be for
millions of years hence.

Carbon is the key element of life, but plants and animals can’t live from carbon alone. Like animals, plants need a host of nutrients in order to grow and thrive. Protein-enabling nitrogen and bone-building phosphorus are crucial elements for life on Earth. Plants draw their nutrients from the soil, and animals get theirs from eating plants. As for the cycling of carbon, the planet’s basic machinery keeps these other elements cycling and provides civilization with these critical ingredients for life. Here again, our dynamic planet stands alone. 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. The incredible lengths that people have gone in the effort to manipulate the machinery—among them hauling buckets of human waste from Chinese towns back to farms, scavenging bison skulls across the North American prairie, and bribing German factory-workers to reveal industrial secrets—have resulted in some of the most profound of humanity’s achievements and changed civilization’s course. We’ll return to these achievements in later chapters.

Time to Fill the Pantry

A stable climate over geologic time and the recycling apparatus for life’s essential nutrients are two of the fundamental foundations for our
planet’s success, and therefore for our success. 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.

Think of the fruits, vegetables, grains, dairy products, and meat in grocery store aisles. You’ll be able to count the number of species on a few hands: mostly corn, wheat, rice, cows, pigs, chickens, and a few others. Even considering fruit and vegetable species, the total is only a tiny percentage of all the species on the planet. These are the species that grow fast enough and are easy enough to collect to make them possible to cultivate on a large scale. But the small number that we eat belies the importance of the diversity of life.

Other, less edible species carry out essential functions
that we cannot live without. Imagine a world without the fungi to decompose dead leaves and branches. We would be buried in debris. Without the species that prey on the pests that eat crops, like the ladybugs that eat aphids and mites, we would have to share more with those nuisances. Bees, beetles, and butterflies fly from flower to flower carrying pollen grains that enable almonds, apples, squash, and many other crops to reproduce. The diversity—even redundancy—of life, with multiple species performing the same function, provides humanity with insurance that if climate change or some other catastrophe wipes out some, there will still be others to do the job. And we need not just a few specimens of each species—we need many. Diversity of genes across individuals ensures that when diseases or other problems arise, some members of a species will withstand the onslaught and survive. These supporting roles are just a few of those performed by species that are not found on the grocer’s shelf. Without these supporting species, humanity would not be able to feed itself. And the functions of the millions of known species, and the millions yet to be discovered, remain largely unknown. Little noticed, these worker species make the difference between a full
and an empty plate.

Today’s Earth teems with life. Life is found in places as varied as the deep sea and glacial ice. No one knows how many species exist on Earth, probably somewhere between 5 and 30 million. The overwhelmingly vast majority of species are the creepy, crawly variety. Species of beetles alone may number half a million. Then there are the many millions of species that are too small to see, such as the thousands of species of tiny, soil-dwelling creatures that recycle our wastes, or those in the sea that are only
visible with a microscope.

The dazzling array of life-forms and the roles different species play in the planetary machinery set our planet apart from all others known so far. It was not always so. On the early Earth, life was not part of the planetary machinery. The first billion years after the planet formed from swirling gases was barren of life. But during that time, the building blocks essential for life somehow appeared. Bombarding comets and meteorites may have brought carbon, water, nitrogen, and maybe phosphorus to the Earth. Or perhaps these building blocks were already present in the early lifeless Earth. The road from these building blocks to the array of life on Earth today was long and winding. 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. Some of these simplest forms of life lived in rotten-smelling sulfur swamps, others in deep-sea vents where they could use energy from heat as it escaped
from the Earth’s interior. For 2 billion years, these simple purple and green bacteria were the dominant forms of life. The next pivot brought another layer of complexity and the most consequential ratchet for the diversity of life. Photosynthesis using water, carbon from the air, and the sun’s energy meant that life could prosper anywhere with sunshine and a little
moisture. Stromatolites, fossils formed by mats of blue-green algae that changed the world billions of years ago, can still be seen today off the western coast of Australia.

From the perspective of the organisms that were used to living in the low-oxygen atmosphere of the time, the evolution of
photosynthesis was a disaster. Oxygen, a by-product of photosynthesis, spiked upward in what geologists variously call the Great Oxygen Event, the Oxygen Catastrophe, the Oxygen Crisis, or the Oxygen Revolution. To organisms accustomed to a no-oxygen atmosphere, the oxygen was toxic. As that hatchet fell, those organisms retreated to stagnant waters and other airless environments. But the crisis made possible other forms of life. With oxygen in the atmosphere, microbial life could eventually evolve to complex plant and animal forms that relied on breathing oxygen to convert food to energy. The oxygen in the atmosphere also gave rise to the ozone layer, the thin shield that protects against the sun’s harmful,
cancer-causing ultraviolet rays.

Sometime around 1.5 billion years ago, more pivot points occurred. Organisms could reproduce sexually. Species could evolve more rapidly to change their shape and size and adapt to their environment based on inherited traits. Plant species evolved based on the precedent of obtaining energy through photosynthesis. An abundance of sponges, jellyfish, corals, and flatworms burst onto the scene about a half billion years later, followed by
fish, insects, birds, and mammals. Here was a new life strategy. Animals could obtain energy not directly from the sun but through digesting plants and other animals in their guts. Fungi, such as yeasts, molds, and mushrooms, wound up with a strategy similar to animals. They, too, absorb their food from other plants and animals, but through their cell walls, without the benefit of stomachs.

New species formed as continents spread apart by plate tectonics, mountain ranges, oceans, and other geographic barriers separated groups of individuals, who exchanged genes with one another and
over time became distinct species. Or individuals mated with others nearby to exploit
a new niche or a new source of food. But the path to the diversity of plant and animal life was not smooth. The geologic record shows devastating, global-scale extinctions of plant and animal species that punctuate the long-term climb to increased diversity. At least five times these life-extinguishing hatchets fell. The most well-known hatchet is the extinction of the dinosaurs about 65 million years ago. Another occurred 250 million years ago and wiped out ninety-six out of every hundred plant and animal species. What caused these extinctions is not exactly clear. Spates of volcanic activity might have raised temperatures from the carbon dioxide or rained down sulfur-laden acid. Perhaps impacts from meteorites spewed dust into the air and blocked light, the likely explanation for the dinosaurs’ death knell. Although these events were devastating, they also created opportunities. With the reset button pushed on the evolutionary trajectory, less dominant groups got a new chance. Were it not for the extinction event that spelled the end of the dinosaurs’ reign, for example, mammals may not have come to be a dominant life form on the planet.

No amount of human ingenuity could re-create the diversity of species. From the inner workings of photosynthesis to the webs of energy-exchanging plants and animals, even the most sophisticated computers cannot mimic the complexities. The result is an amazing endowment from nature, ripe for human ingenuity’s grasp, as we select those species that are useful, tweak those that are not quite right for our needs, and even destroy those that are harmful. But humanity cannot create new species from the building blocks of life, at least not yet. This is another foundational feature of the planet on which we depend for survival, but over which we have no control.

The basic foundations for our success as a species are far beyond our reach. The nonnegotiable conditions for the rise of humans on the
planet and our prominence today rest on long-term geologic features and an evolutionary history that we did not shape. We cannot alter the magnet in a planet’s core, churn the wheel of plate tectonics, or push a planet into a Habitable Zone. We cannot re-create the diversity of life. We cannot restage the physics and chemistry that governed the early Earth, or the biology that came later. But there is still plenty of leeway. The story that leads to the Big Ratchet is about the manipulation of those shorter-term features of our amazing planet, the features that we can control. The planetary platform provides the opportunity. Human culture provides the ingenuity.

3: ENTER HUMAN INGENUITY

O
N THE
19
TH OF
M
AY
, 1845, the HMS
Erebus
and the HMS
Terror
set sail from Greenhithe, England. The Lords of the Admiralty of the United Kingdom had charged the leader of the expedition, Sir John Franklin, with finding the Northwest Passage, the elusive and much-sought navigable path linking Europe and Asia through the icy northern seas.

This was Franklin’s fourth trip to the Arctic. He had experienced the treachery of the icebergs; the dark, cold winters; and the danger of starvation. Despite the prejudices of the times and the common presumption of British superiority over native cultures, Franklin knew that the Inuit were experts at surviving the Arctic’s stark winters. He was prepared to go outside the norms of British culture, to eat seal blubber and hunt walrus, if provisions ran bare. Before setting forth on the
Erebus
and
Terror
, Franklin remarked with confidence, “Where Esquimaux do live out a fair period of life, it is but reasonable to suppose that Europeans may subsist and
survive for many years.”

The expedition set sail with 132 crewmen and officers. Provisions included 16,884 pounds of biscuits, 2,490 gallons of ale and porter,
15,664 pounds of preserved meat in tin cans, 6,859 pounds of sugar, 1,608 pounds of butter, 500 pounds of mustard, and 100
pounds of pepper. The men crossed the Atlantic and spent the first winter docked at Beechey Island above the Arctic Circle. Pneumonia claimed the lives of three crewmen that winter.

As winter thawed in 1846, the
Erebus
and
Terror
sailed southward toward King William Island. Somewhere along the way, the ships became snarled in ice. Provisions dwindled. The crew grew weak with scurvy. By April of the following year, 24 more men had died. Sir John himself died in June of that year. The remaining 105 men abandoned the ships and headed on foot toward the mouth of the Great Fish River on the mainland. Many died along the way. For the crew who survived, Great Fish River turned out to be an unfortunate choice. It was such poor hunting ground that native Inuit avoided it. The men starved. Every last man who had set sail from Greenhithe five years earlier perished from tuberculosis, scurvy, or starvation.