By Dr. Robert Thorson
Curving across America’s Deep South is a “Black Belt” that runs from western Tennessee down to Montgomery, Ala., then back northeast through the Carolinas. During the 2016 presidential election, this swath was an anomaly of Clinton Democrats surrounded by a sea of Trump Republicans. It coincides with a demographic belt dominated by African-American voters, which, in turn, lies above a geological belt of soft rock: a band of nutrient-laden shale created about 75 million years ago when sea levels stood much higher than today. When weathered into soil, this shale is perfect for growing cotton, a cash crop planted at a time when chattel slavery was an accepted way of life, and when the water-powered textile mills of New England were hungry for raw material.
In “Origins: How Earth’s History Shaped Human History,” astrobiologist and professor of science communication Lewis Dartnell argues that “there is a clear causal chain taking us from the politics and socio-economic conditions of today, to their roots in historical agricultural systems, and then further back to the geological tapestry of the ground beneath our feet.” This linkage between ancient rock and modern democracy is one among hundreds of compelling examples he uses to prove what the book’s subtitle proclaims—that our biological beginnings and cultural histories have been shaped by earth history in ways that have been sadly neglected by school curricula and cultural understandings.
Origins
By Lewis Dartnell Basic, 346 pages, $30
“Origins” is a Big History, a grand synthesis that draws from many fields. A different black belt in Europe, Mr. Dartnell notes, links Britain’s Labor Party to much older Carboniferous-era coal, and to the miners who toiled to extract it. Ancient Egypt emerged when a weakened monsoon forced inhabitants to cluster together in the Nile Valley. Modern banking was developed as a 17th-century Dutch solution to rising seas—a way to finance coastal defenses “with the pooling of resources from the community.” China is poised to monopolize an economically vital supply of rare-earth metals, particularly the indium and gallium used in our screens.
Mr. Dartnell explores, in sequence, human origins, the tectonics and climates governing ancient history, the whys of the rise of civilizations, the ur-causes of maritime geographies, nonmetallic and metallic resources, the earthly underpinnings of nomadic and sedentary cultures, the influence of winds and ocean currents throughout history, and the recent acceleration of energy use and its consequences. The final sentence he offers as summation—”The Earth made us”—can be read two ways, capturing the parallel themes of “Origins.”
With emphasis on “us,” it refers to the origin of the genus Homo, a clade of naked apes giving rise to our species, H. sapiens, the greatest biological superpower of all time, one so potent that all others in our genus are extinct. Why did this emergence take place in the cradle of the East African Rift and nowhere else? And why did the arrival of our genus broadly coincide with the onset of highfrequency climatic swings about two million years ago? Mr. Dartnell concludes that this recently uplifted and intricately rifted landscape created a mosaic of habitats dominated by lakes that further amplified the climatic oscillations between dry-wet and hot-cool conditions. Change was dramatic, frequent, unpredictable and stressful. Thus “intelligence” became “the evolutionary solution to the problem of an environment that shifts faster than natural selection can adapt the body . . . driving . . . ever more flexible and intelligent behavior.”
With emphasis on “made,” it refers to the determinism of physical geography and of the material and energy resources we’ve used to create our civilizations and defeat our enemies. “We not only build our cities,” he writes, “within the landscape—near the coastline, in a fertile river valley or close to hills with mineral resources—but we also make them of the landscape.” Ranging in time from the mud bricks of ancient Babylon to the glass-steel towers of modern megacities, he chronicles how the stepwise geological history of our planet set the stage for the stepwise technological history of our world: in material from stone to copper to iron to alloys to composites; and in energy from human muscle to draft animals to steam to gasoline to nuclear fission. Modern digital technology is the culminating grand sum of all these cumulative steps: “of the 83 stable (non-radioactive) elements in existence, around 70 are used in making an everyday consumer device like a smartphone.”
Mr. Dartnell’s breezy style is full of word play, setting him far from the plodding crowd of many science writers. Teasing Californians in a footnote, he claims that the world’s “original Silicon Valley” was the great rift valley of East Africa, where our ancestors made silica-rich tools of quartzite, flint, chert and obsidian. Explaining the evolution of Perissodactyla, an order of modern mammals who have odd numbers of toes, he offers a clever analogy: “In effect, horses gallop around on the same finger you would use to flip someone the bird.” Invoking a touch of black humor, he describes the catastrophic cascade of death during Earth’s greatest mass extinction (volcanic eruptions, ignited coal beds, acid rain, neurotoxic metals, roasting greenhouse gases, oxygen-deprived oceans)—as a “multi-whammy at the end of the Permian.”
This lively style is peppered by pithy summaries. Noting that ancient civilizations align with plate boundaries, he writes, “We are the children of plate tectonics.” Explaining how the rock of our homeland continents came to be: “Granite is the sweat of plate tectonics.” And my favorite: “And so the planet rusted.”
This last is a nonchalant reference to Mr. Dartnell’s candidate for “the most significant revolution in the history of the planet,” the GOE, the Great Oxidation Event dating to 2.42 billion years ago. Species-scale revolutions such as cognition, agriculture, fossil fuels and digital technology are dwarfed by true planetary revolutions like the GOE. That’s when oxygen, a waste gas of photosynthetic microbes, was vented into a previously stable atmosphere, creating blue skies from a yellowish “smoggy photochemical haze.” Oxygen, a precondition for advanced life, gave us the air we breathe, the steel of our lives and the fire on which our species depends, whether for flaming defense against savanna predators or for the internal combustion engines of our transportation network.
Though Mr. Dartnell’s style is light, extensive footnotes offer delightful expansions of specific topics. Scholarly documentation is reserved for numbered notes linked to an exhaustive bibliography. There a few minor errors of fact and overgeneralization that only specialists would quibble with: The “entire history of civilisation,” for example, is far longer than a “flash in the current interglacial period,” which is not a “transient spell of climatic stability.”
Throughout my teaching career, I’ve been using the mantra “No rock, no ecosystem, no culture” as shorthand for the larger story that “Origins” elucidates. Ultimately, everything in world history traces back to the deep time of planetary history, obliterating the human conceit that there is such a thing as “prehistory.” “The Earth made us”: That’s past tense. The Earth will continue to make us: That’s future certainty.