Broadly speaking, a society facing the end of an anabolic cycle faces a choice between two strategies. One strategy is to move toward a steady state in which C(p) = M(p), and d(R) . r(R) for every economically significant resource. Barring the presence of environmental limits, this requires social controls to keep capital stocks down to a level at which maintenance costs can be met from current production, so that intake of resources can be kept at or below replenishment rates. This can require difficult collective choices, but as long as resource availability remains stable, controls on capital growth stay in place, and the society escapes major exogenous crises, this strategy can be pursued indefinitely.
The alternative strategy is to attempt to prolong the anabolic cycle through efforts to accelerate intake of resources through military conquest, new technology, or other means. Since increasing production increases W(p) and increasing capital stocks lead to increased W(c), however, such efforts drive further increases in M(p). A society that attempts to maintain an anabolic cycle indefinitely must therefore expand its use of resources at an ever-increasing rate to keep C(p) from dropping below M(p). Since this exacerbates problems with depletion, as discussed above, this strategy may prove counterproductive.
If the attempt to achieve a steady state fails, or if efforts at increasing resource intake fall irrevocably behind rising M(p), a society enters a state of contraction, in which production of new capital does not make up for losses due to waste:
n C(p) < M(p) â> contraction (4)
The process of contraction takes one of two general forms, depending on the replenishment rate of resources used by the society. A society that uses resources
at or below
the replenishment rate (d(R)/r(R) . 1), when production of new capital falls short of maintenance needs, enters a maintenance crisis in which capital of all kinds cannot be maintained and is converted to waste: physical capital is destroyed or spoiled, human populations decline in number, large-scale social organizations disintegrate into smaller and more economical forms, and information is lost. Because resources are not depleted, maintenance crises are generally self-limiting. As capital is lost, M(p) declines steeply, while declines in C(p) due to capital loss are cushioned to some extent by the steady supply of resources. This allows a return to a steady state or the start of a new anabolic cycle once the conversion of capital to waste brings M(p) back below C(p).
A society that uses resources
beyond
the replenishment rate (d(R)/r(R) > 1), when production of new capital falls short of maintenance needs, risks a depletion crisis in which key features of a maintenance crisis are amplified by the impact of depletion on production. As M(p) exceeds C(p) and capital can no longer be maintained, it is converted to waste and unavailable for use. Since depletion requires progressively greater investments of capital in production, the loss of capital affects production more seriously than in an equivalent maintenance crisis. Meanwhile further production, even at a diminished rate, requires further use of depleted resources, exacerbating the impact of depletion and the need for increased capital to maintain production. With demand for capital rising as the supply of capital falls, C(p) tends to decrease faster than M(p) and perpetuate the crisis. The result is a catabolic cycle, a self-reinforcing process in which C(p) stays below M(p) while both decline. Catabolic cycles may occur in maintenance crises if the gap between C(p) and M(p) is large enough, but they tend to be self-limiting in such cases. In depletion crises, by contrast, catabolic cycles can proceed to catabolic collapse, in which C(p) approaches zero and most of a society's capital is converted to waste.
A society in a depletion crisis does not inevitably proceed to catabolic collapse. If depletion is limited, so that decreased demand for resources as a consequence of diminished production brings d(R) back below r(R), the accelerated fall in C(p) may not take place and the crisis may play out much like a maintenance crisis. If the gap between C(p) and M(p) is modest, nonproductive capital may either be diverted to production to raise C(p) or preferentially converted to waste to bring down M(p), forcing C(p) and M(p) temporarily into balance in order to buy time for a transition to a steady state. A society in which depletion is advanced and M(p) rapidly increasing relative to C(p), though, may not be able to escape catabolic collapse even if such steps are taken. Cultural and political factors may also make efforts to avoid catabolic collapse difficult to accomplish, or indeed to contemplate.
Testing the Model
These two forms of collapse, maintenance crisis leading to recovery, and depletion crisis leading to catabolic collapse, are to some extent ideal types, forming two ends of a complex spectrum of societal breakdown. Most historical examples of collapse fall somewhere in between the two. The limitations of the abstract and extremely simplified model on which the theory is based should also be kept firmly in mind when attempting to apply it to past or present examples. Still, a survey of historical examples shows that many of them have features which support the model proposed in this section.
Closest to the maintenance-crisis end of the spectrum are tribal societies such as the Kachin of Burma. Kachin communities cycle up and down from relatively decentralized to relatively centralized social forms without significant losses of physical, human, or information capital. In this case, anabolic cycles lead to the growth of organizational capital in the form of relatively centralized social forms, but the maintenance costs of this organizational capital turn out to be unsustainable, leading to maintenance crises, loss of social capital, and the restoration of more decentralized and thus less resource- and capital-intensive social forms (Leach 1954).
Essentially the same process on a larger and more destructive scale characterizes the history of imperial China from the 10th century bce to the end of the 19th century ce. Efficient cereal agriculture and local market economies provided the foundation for a series of anabolic cycles resulting in the establishment of centralized imperial dynastic states (Gates 1996; Di Cosmo 1999). These anabolic cycles drove increases in population, public works such as canals and flood control projects, and sociopolitical organization, all of which proved unsustainable over the long term. As maintenance costs exceeded the imperial government's resources, repeated maintenance crises led to the breakup of national unity, invasion by neighboring peoples, loss of infrastructure, and steep declines in population (Ho 1970; Di Cosmo 1999). Imperial China's resource base had a relatively high replenishment rate, due largely to the long-term sustainability of traditional Chinese agriculture and the use of human and animal muscle as the primary energy sources, so any significant resource depletion could be reversed once population levels dropped (Elvin 1993). Though resource depletion played a limited role, the maintenance crises of imperial China were self-limiting and resulted in contraction to more modest levels of population and sociopolitical organization, rather than the total collapse of the society.
The collapse of the western Roman Empire, by contrast, was a catabolic collapse driven by a combined maintenance and resource crisis. While the ancient Mediterranean world, like imperial China, was primarily dependent on readily replenished resources, the Empire itself was the product of an anabolic cycle fueled by easily depleted resources and driven by Roman military superiority. Beginning in the third century bce, Roman expansion transformed the capital of other societies into resources for Rome as country after country was conquered and stripped of movable wealth. Each new conquest increased the Roman resource base and helped pay for further conquests. After the first century ce, though, further expansion failed to pay its own costs. All remaining peoples within the reach of Rome were either barbarian tribes with little wealth, such as the Germans, or rival empires capable of defending themselves, such as the Parthians ( Jones 1974). Without income from new conquests, the maintenance costs of empire proved unsustainable, and a catabolic cycle followed rapidly. The first major breakdown in the imperial system came in 166 ce, and further crises followed until the Western empire ceased to exist in 476 ce (Grant 1990; Grant 1999).
The Roman collapse has an instructive feature which offers further support to the model presented above. In 297, the emperor Diocletian divided the empire into western and eastern halves. Coordination between them waned, and by the death of Theodosius I in 395, the two halves of the empire were effectively independent states. Since the western empire produced one-third the revenues of the eastern empire, but had more than twice as much northern frontier to defend against barbarian encroachments, this placed most of the original empire's vulnerabilities in the western half and most of its remaining resources in the eastern half. In terms of the catabolic collapse model, the eastern empire allowed massive quantities of relatively unproductive, high-maintenance capital to be converted to waste, bringing its M(p) below its remaining C(p) and breaking out of the catabolic cycle. The eastern empire's territory decreased further with the Muslim conquests of the seventh and eighth centuries ce; while this was involuntary, the effects were the same. Successfully shifting to a level of organization that could be supported sustainably by trade and agriculture within a more manageable territory, the eastern empire survived for nearly a millennium longer than its western twin (Bury 1923).
Near the depletion crisis end of the spectrum is the collapse of the Lowland Classic Maya in the eighth, ninth, and tenth centuries of the Common Era. The most widely accepted model of the Maya collapse depends on demographic and paleoecologi-cal evidence that Maya populations grew to a level that could not be indefinitely supported by Mayan agricultural practices on the nutrient- poor laterite soils of the Yucatan lowlands. In terms of the present model, the key resource of soil fertility was used at a rate exceeding its replenishment rate, suffering severe depletion as a result. Mayan polities also invested a large proportion of C(p) in monumental building programs, which raised maintenance costs but could not be readily used for production, and they maintained these programs up to the beginning of the Terminal Classic period. The result was a “rolling collapse” over two centuries, from c. 750 ce to c. 950 ce, in which Lowland Maya populations declined precipitously and scores of urban centers were abandoned to the jungle (Willey and Shimkin 1973; Lowe 1985; Webster 2002).
The Lowland Classic Maya collapse is particularly suggestive in that it appears to have been preceded by at least two previous breakdowns. Preclassic sites such as El Mirador and Becan show many of the same artistic and cultural elements as Classic Maya urban centers, but they were abandoned in a poorly documented earlier collapse around 150 ce (Webster 2002). A second episode, the so-called Hiatus between the Early Classic and Late Classic periods (500â600 ce), saw sharp declines in monumental building and the breakdown of centralized political systems (Willey 1974). Whether these events were maintenance crises preceding the final resource crisis of the Terminal Classic, or whether some other explanation is called for, is difficult to determine from the available evidence.
Features of comparative sociology outside the realm of collapse processes also offer support to the catabolic collapse model. One implication of the model is that societies that persist over extended periods will tend to have social mechanisms for limiting the growth of capital, thus artificially lowering M(p) below C(p). Such mechanisms do, in fact, exist in a wide range of societies. Among the most common are systems in which modest amounts of unproductive capital are regularly converted to waste. Examples include aspects of the potlatch economy among Native Americans of northwest North America (Kotschar 1950; Rosman and Rubel 1971; Beck 1993) and the ritual deposition of prestige metalwork in lakes and rivers by Bronze and Iron Age peoples in much of western Europe (Bradley 1990; Randsborg 1995). Such systems have been interpreted in many ways (Michaelson 1979), but in terms of the model, one of their functions is to divert some of C(p) away from capital stocks requiring maintenance, thus artificially lowering W(c) and making a catabolic cycle less likely.
Such practices clearly have many other meanings and functions within societies. Nor does this interpretation require any awareness within societies themselves that systems of capital destruction prevent catabolic cycles. Rather, if such systems make catabolic collapse less likely, cultures that adopt such systems for other reasons are more likely to survive over the long term and to pass on such cultural elements to neighboring or successor societies.
Conclusion: Collapse as a Succession Process
Even within the social sciences, the process by which complex societies give way to smaller and simpler ones has often been presented in language drawn from literary tragedy, as though the loss of sociocultural complexity necessarily warranted a negative value judgment. This is understandable, because the collapse of civilizations often involves catastrophic human mortality and the loss of priceless cultural treasures, but like any value judgment it can obscure important features of the matter at hand.
A less problematic approach to the phenomenon of collapse derives from the idea of succession, a basic concept in the ecology of nonhuman organisms. Succession describes the process by which an area not yet occupied by living things is colonized by a variety of biotic assemblages called “seres,” each replacing a prior sere and then being replaced by another, until the process concludes with a stable, self-perpetuating climax community (Odum 1969).
One feature of succession true of many different environments is a difference in resource use between earlier and later seres. Species characteristic of earlier seral stages tend to maximize control of resources and production of biomass, even at the cost of inefficiency; thus, such species tend to maximize production and distribution of offspring even when this means the great majority of offspring fail to reach reproductive maturity. Species typical of later seres, by contrast, tend to maximize the efficiency of their resource use, even at the cost of limits to biomass production and the distribution of individual organisms; thus, these species tend to maximize energy investment in individual offspring even when this means that offspring are few and the species fails to occupy all available niche spaces. Species of the first type, termed “R-selected” species in the ecological literature, have specialized to flourish opportunistically in disturbed environments, while those of the second type, or “K-selected” species, have specialized to form stable biotic communities that change only with shifts in the broader environment (Odum 1969).