The Dirt on Ancient Civilization: Lost Soils and Lessons Lost

     Recently, the Mermaid’s Tale hosted a lively discussion about the impact of agriculture on society, from its Neolithic beginnings until the present day. I personally see the move from hunting and gathering to farming not unlike a visit to the dentist: painful but necessary. Painful because, too often, its come at environmental cost, but necessary because the hallmarks of society (art, modern medicine, the Yankees) could never have been realized without the social organization that farming demands. Still, there was consensus that not all farming is the same, that certain agricultural practices are more sustainable than others, and that the repeat offender, human shortsightedness, is not inherent to agriculture, but to people (and here we can agree with the prophet of Ecclesiastes who said there is nothing new under the sun). But that doesn't discount agriculture's unique expression of this all too human flaw. Perhaps today's greatest threat in this regard, provoked under current agricultural regimes, is topsoil degradation and loss. The problem, exacerbated by global markets and soaring demographics, has blown by any measure of sustainability, with annual rates of worldwide topsoil loss at 24 billion tons. With business remaining as usual, the planet will be stripped of all topsoil within a century's time. If you value humanity, you should be outraged.
      As a student of archaeology, I thought a deep-time perspective on soil loss might help. After all, both farmers and archaeologists value dirt, the one for what lies above it, the other for what lies below; and besides, soil and civilization have long shared an intimate relationship, each dependent on the other for health and survival. Healthy soils are home to billions and billions of microbes. When stripped of plant cover and sapped of life, the remaining dirt can no longer support crops. In order for meaningful soil conservation to take effect, an individual's sense of responsibility has to extend beyond physical space (be it local or global, though that's an important part, too) into historical space, as well. Only then can we regard agriculture for what it was, is, and must remain: a social institution to be valuated beyond dollars and cents.
     Moreover, a recent article in Science, "Dust Unto Dust," made the oft repeated distortion that ancient farmers had little regard for environmental stewardship. This simply isn't true. My six mentally stimulating but fiscally foolish years spent stooped over Greek and Latin texts in fusty libraries with fools in old style hats and coats will prove it. The Greeks and Romans, just like the early settlers of America, saw the harm in their practices, but for various and sundry reasons failed to change course, at times resulting in social catastrophe (for the U.S., this was epitomized in the North American "dust bowl" of the 1930s; for the Greeks and Romans, the abandonment of numerous cities and towns, such as Timgad in present day Algeria). The age-old struggle with soil preservation does not represent nature's inherent inability to accommodate civilization, but civilization's inability to accommodate nature.

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The Roman colonial town of Timgad, once famous for its fertile hinterland, had even in antiquity been reduced to desert 

    Topsoil is quite literally the foundation of every society - footings and stomachs depend on it. Perhaps it's not coincidence that the name Adam, related to the noun adamah in Hebrew, means "soil" or "earth" (from the Semitic root "ADM"), while the name Eve, Adam's female counterpart, is related to the noun havvah (the Semitic root "HYW"), meaning "life-source," with the result that the biblical creation narrative links soil to life (and vice versa) from the beginnings of time. In the Babylonian creation myth of Atrahasis, man is fashioned from the alluvial clays of southern Iraq. In fact, the Latin word for man, homo, is a derivation of the word humus, meaning "soil" and "earth." Fun etymologies aside, when topsoil is exhausted for short-term gain, decay and loss unleash a cascade of direct and indirect consequences for farmlands, forests, wetlands and watersheds, many of long-lasting effect.

   

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     Henry David Thoreau once said that

The civilized nations — Greece, Rome, England — have been sustained by the primitive forests which anciently rotted where they stand. They survive as long as the soil is not exhausted. Alas for human culture! Little is to be expected of a nation, when the vegetable mould is exhausted, and it is compelled to make manure of the bones of its fathers.

Unfortunately, the automaticity of our everyday experience lacks the immediacy of Thoreau's words. Even at today's rate, soil loss occurs slow enough to go unnoticed by the average viewer. It doesn't help that less than 1% of the U.S. population, for instance, feeds the other 99%, meaning that our eyes are not only metaphorically but also physically averted. In his excellent novel, Dirt: The Erosion of Civilizations, David R. Montgomery points out that soil is an undervalued resource in the modern world. In fact, he goes so far as to say that within dirt (or more specifically, its geological narrative of misuse) can be found the graveyard of successive civilizations.

Photo taken by the author in Oxford, UK

     Agricultural harm to the environment has a long and complicated history. It wasn't until the 7th and 8th centuries A.D. in northern Europe that plows began to employ a vertical knife, horizontal share and moldboard to cut furrows, directly scarring the earth's surface. Prior to this, enough indirect damage was caused, through violation of fallow, disregard for overgrazing and/or lack of crop diversity, that eventually, divested of nutrients and biota, soil was no longer fertile soil, but simply sterile dirt. For the Mediterranean environment especially, a healthy topsoil required forests to preserve soil structure, preventing erosion and flooding. Unfortunately for the Greeks and Romans, deforestation became widespread, the result of resource extraction and clearance for agriculture.
     Forests supplied the very fabric of life in the Classical world: materials for construction and fuel, as well as medicinals and dyes. Wood and charcoal fired ceramics to be found in every house; drew pitch from pinewood; smelted the metals in foundries; and leached fertilizer from limestone. For most private houses and public buildings, timber was the material of choice. Navies depended on lumber for the construction of their vessels, while armies used wood to build siege engines, weapons, and armor. It's no wonder that the Greek word for wood, "hyle", became synonymous with "matter" and "substance." The word "materia" in Latin represented all three.
     While populations were relatively small, daily existence depended on wood and its by-products, laying whole landscapes bare. Presumably, many could sympathize with Vergil (70 - 19 B.C.) when he said,

My hearth is piled with branches of pitch-pine;

Free burns my faithful fire, and every hour

My walls are black with smoke (Ecologues 7.49-50).

Moreover, cleared forests weren't given time to regenerate, but were replaced with agricultural land. Ancient writers were aware of the environmental consequences. Vitruvius (first century B.C.), Roman author and engineer, knew well the role of forests in supporting the flow of water for natural springs:

Water ... is to be most sought in mountains and northern regions, because in these parts it is found of sweeter quality, more wholesome and abundant. For such places are turned away from the sun's course, and in these especially are many forest trees; ... nor do the sun's rays reach the earth directly and cause the moisture to evaporate. Valleys between mountains are subject to much rain, and because of the dense forests, snow stands there much longer under the shadow of the trees and the hills. Then it melts and percolates through the interstices of the earth and so reaches the lowest spurs of the mountains, from which the product of the spring flows and bursts forth (De Architectura 8.1.6-7).

And Plato (427-347 B.C.) lamented the state of the denuded landscape following torrential rains:

What now remains compared with what then existed is like the skeleton of a sick man, all the fat and soft earth having wasted away, and only the bare framework of the land being left (Critias 111B).

Over time, intensive farming and deforestation led to soil loss in upland valleys, with resulting sedimentation and siltation in lowlands and coastal plains. The consequences were often complex, including reduced water retention for underground aquifers, the formation of new disease vectors (such as malarial swamps and marshes), increased aridity and wind damage, as well as the marginalization of agriculturally (farm) and socially (urban) productive land, creating dependencies of distance that only heightened ecological burdens.
     In Greece and Rome, geo-archaeology has shown that meaningful erosion only followed settlement and farming. After certain environmental thresholds were crossed, great periods of seeming stability gave way to outright destabilization. Archaeological investigations near Rome have shown that erosional rates spiked during the second century B.C., a time of the Gracchan reforms that extended land clearance. Before agricultural reform, erosion rates averaged from 2-3 centimeters per every thousand years; following reform, the rate climbed to 20-40 centimeters. Similar phenomena have been seen in the archaeological record of Greece. Thermopylae (the "hot gates" of Frank Miller's 300 movie), famous for the battle that took place there in 480 B.C., saw a vastly outnumbered Greek force successfully repel an advancing Persian army, precisely because the narrow coastal strip, hemmed in by cliffs and sea, provided a tactical advantage. Today, years of accumulating river silt have left the shoreline some 5 miles from the site of the ancient confrontation. Unfortunately for Xerxes, he was two millennia too early.

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Again, the textual sources show a keen awareness of topsoil degradation, even though that awareness often failed to bring about systematic change. Columella (4 - 70 A.D.), for instance, noted in his De Re Rustica that, following the clearance of forest for agricultural land, crop production waned in successive years, not because the cleared lands were "young," but because the soil, now deprived of the roots and foliage of woodland plants, was malnourished (2.1.5-6).

   The expansion of agriculture was a prime contributor to erosion. Lucretius said that entrepreneurial farmers "made the woods climb higher up the mountains, yielding the lowlands to be tilled and tended (De Rerum Natura 5.1370-71)." Over time, this forced both farmers and loggers into hillier land that, when exploited, posed an ever greater risk to topsoil runoff and flooding. In the Mediterranean basin, timing and intensity of rainfall mattered far more than annual totals.  Following deforestation, the mountainous landscape was especially vulnerable to sudden, violent rains. Unprotected first by the previous forest cover and then destabilized without the natural root system, soil didn't have a fighting chance. Pliny wrote, "often indeed devastating torrents unite when from hills has been cut away the wood that used to hold the rains and absorb them (HN 31.30 (53)." 
     In addition to land clearance for farming, animals that wandered the land posed an even greater danger. Varro (116-27 B.C.) wrote, "Grazing cattle do not produce what grows on the land, but tear it off with their teeth (De Re Rustica 2.2.8, 11-12)." Foraging animals (particularly goats on hill slopes) functioned as a sort of secondary threat, making whatever degradation came before, permanent, ensuring that ecological niches were never given adequate time to regenerate. Ultimately, soil loss required the complicity of entire ancient societies: merchants, farmers, and pastoralists.
    For some, it's interesting in its own right to know that the Greeks and Romans knew how to use natural fertilizer, to practice crop rotation, and to construct terraces, that is, knew how to treat the environment responsibly. But it's perhaps universally important to know that, despite that knowledge, they often failed to do so, with topsoil loss leading to famine, disease, and fragile social structures. Today, we as a global community are facing a similar crisis, together with a similar knowledge base. But we have the unique advantage of historical perspective. My current area of study, Mesopotamia, experienced social collapse because of over salinization from the maximizing strategies of short-sighted agriculture, millennia before men wore togas. Mesopotamian tyrants, like modern politicians, were consciously aware of their short shelf-life, with the result that policies affecting a future beyond their own terms in office were little more than afterthoughts. Today, if we fail to adapt, to ask ourselves and our politicians for long-term solutions, we can expect the same outcome. To think otherwise is fatal hubris, the prime mover of historical change seen in the works of men like Herodotus, Thucydides and Polybius.
     Topsoil loss is inevitable in both the agricultural and natural world, but that doesn't mean we can't treat it sustainably. In past and present, local production for global consumption has had devastating effect. Whether it was Rome's monopolization of North Africa for cash crop industries, or America's impetuous push west to sustain tobacco exports, formerly fertile lands were impoverished in the name of capital. When this happened, a type of economic colonialism occurred, dividing formerly sustainable lands into decadent cores and imbalanced peripheries. The difference now, however, is that societies in the plural is now society in the singular, and the loss of mankind's ability to produce food will be of global consequence.
    In the modern regimes of soaring populations and unpredictable climate, crop rotation and diversification are critical, as well as the move to lower-input, no-till farming. In addition, governments should stop subsidizing harmful agricultural practices, and consumers have to adapt to appropriate-scale markets. Only then will soil increase in biodiversity and organic content, bringing with it the much needed benefit of carbon sequestration. Most importantly, individuals need a lived sense (past, present and future) of social responsibility. And we would be wise to keep in mind Faulkner's famous line: "The past is never dead. It's not even past." Indeed, I would say it's right under our feet.