The human species has long lived on the edge of starvation. Now we produce enough food so that all 7 billion of us could eat nearly 3,000 calories every day. This is such an astonishing transformation as to verge on the miraculous. The Big Ratchet is the story of how it happened, of the ratchets—the technologies and innovations, big and small—that propelled our species from hunters and gatherers on the savannahs of Africa to shoppers in the aisles of the supermarket. To some, these technologies are a sign of our greatness. To others, they are monuments to our hubris, as each new innovation has created new opportunities for disaster. MacArthur fellow and Columbia University professor Ruth DeFries argues that this debate—played out every day between technophiles and environmentalists— is the wrong one to have. This cycle of crisis and growth is the story of our species, and understanding this pattern explains not just how we reached this point in our history, but how we might survive and thrive in millennia to come. (from book website)
The word “Anthropocene” does not appear in Ruth DeFries’ account of “the long arc of our species’ quest to feed itself” (p. 15). But the richly interdisciplinary story she tells will sound familiar to anyone who has followed discussions of the concept. An obvious point of contact can be seen in her title. The “big ratchet” is the expansion in the capacity to produce food that is more or less coincident with the “Great Acceleration” described by Steffan et al (2015) that occurred after World War II.
That moment, of course, is a candidate for the beginning of the Anthropocene. But even advocates of the view that the Great Acceleration marks the transition away from the Holocene acknowledge that what was accelerated were existing trends. For DeFries, the big ratchet of the second half of the twentieth century is, similarly, only the biggest of a series of qualitatively similar developments that stretch back 13,000 years, to the emergence of agriculture.
Thus, though I don’t know if she has taken a position on the start-date question, DeFries does point to key phenomena that are associated with the “early Anthropocene” view. To be sure, she does not discuss the climate-altering effects of early agriculture. And although she does address ways humans have, for millennia, intervened in the natural cycles of nitrogen and phosphorus, she does not focus on this from a specifically geological (or Earth System) perspective. Nonetheless, her explanation of the “human ingenuity” deployed in agriculture draws on ideas about human sociocultural evolution we discussed in this blog as part of the Anthropocene Biosphere Project earlier this year. Like Erle Ellis (with whom she has published) she seeks to understand the pervasive human modification of the Earth we see now in terms of an understanding of core and distinctively human capabilities—what it is about homo sapiens that has led to a condition of the planet where it seems reasonable to say that our species has pushed it into a new geological period.
Although DeFries does not explicitly address the Anthropocene, she does take up the other central theme of this blog, habitability. She emphasizes an idea I have tried to deemphasize, in a way. In my posts I have often stressed the ways that people (and other creatures) make the places they live habitable; I have tried to present habitability as an accomplishment, not a given (hence my fascination with niche construction). The Big Ratchet is an important corrective. DeFries points to physical conditions that must be in place in order for Earth to support the kind of life which can then engage in the activity of transforming those conditions to make them more habitable.
Some of those conditions are cosmic—Earth is at the right distance from the sun, so that over the period of time needed for complex life to evolve water occurs as a liquid, rather than a solid or a vapor. Others have to do with the characteristics of Earth itself. It has a magnetic core, affording protection from the radiation in the solar wind. More importantly, for DeFries, key elements—carbon, nitrogen, phosphorus—are cycled through the Earth system. This is “the most precious, and the least appreciated, foundation for human civilization” (p. 23). Finally, Earth is home to a staggering diversity of life forms. Human beings make use of a small number directly, but depend in known and unknown ways on incalculably complex interactions among countless others.
DeFries concludes that “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” (p. 33). In other words, there are some givens without which Earth would not be habitable; habitability is not constructed all the way down.
DeFries thus provides a crucial reminder that to the extent that habitability is “accomplished” it is done so with given materials, and under given constraints. Understanding those constraints is obviously essential to understanding the human project of improving the conditions for their lives. For me, her explanations of the roles of nitrogen and phosphorus as constraints on human wellbeing (in terms of individual nutrition and hence of population growth) are particularly illuminating. For she shows precisely how people have enhanced habitability by making those elements available for agriculture in ways unmanipulated nature does not.
Thus, DeFries is clear that human beings contribute substantially to habitability; that is the role of human ingenuity, which takes advantage of the materials it finds and the processes it learns to control. But she is also clear that this human effort is not uniformly or consistently successful. She presents a recurring pattern. First, ingenuity “ratchets up” habitability by deploying some technique—for example, by planting crops. Second, a “hatchet” falls, impinging on habitability—for example, the soil becomes depleted. Third, people “pivot” away from the first strategy for enhancing habitability (which led to the hatchet), and use their ingenuity to develop a new technique—for example, by learning to apply fertilizer to improve the soil.
DeFries assumes that this dynamic is on-going: for each ratchet there will be some hatchet, followed by a pivot—or as she puts it, “Solutions will create new problems, and problems will generate new solutions” (p. 15). Such has been the broad outline of human history, which gives some grounds for thinking that the pattern will continue—but does not constitute a guarantee.
The Big Ratchet deepened my appreciation of the physical dimension of habitability—the features of the planet that must be in place, the kinds of manipulations human beings have performed to make their civilizations physically possible, and the adverse consequences that inevitably attend those manipulations. But it is important to note that the conception of habitability the book informs is, so to speak, a metabolic one: it is habitability as the set of physical conditions that underlie organic survival. DeFries does not address the normative dimension of habitability we have explored in this blog. To be a normative concept habitability must be seen not simply in terms of providing for survival, but of enabling a good life—where physical requirements are necessary but not sufficient for living well (see this post, for example). The story DeFries tells is thus a necessary part of an understanding of habitability; it identifies constraints within which ways of supplementing our understanding must operate.