the plan for the future

The Collapse of Complex Societies

12 February 2022

Author of the book: Joseph Tainter


The breakdown of societies and civilisations is an underinvestigated domain considering the likelihood and implications of such an event. As humanity uses far more resources than nature can replace, it is a realistic possibility with dramatic consequences. Billions of people could die in famines and wars. The alternative would be a more graceful retraction to sustainable lifestyles.

This document contains redacted course notes on the book The Collapse of Complex Societies of Joseph Tainter. According to Tainter, societies and civilisations collapse due to diminishing marginal returns on investments in societal complexity. At some point, the cost of additional complexity starts to exceed the benefits. It may be a reason why interest rates have gone negative.

Going forward, Natural Money may be helpful in mitigating a collapse and turn it into a more graceful process. We live in a monetary economy, so with negative interest rates it become possible to sustain activities with low and even negative yields for a longer period than otherwise would have been possible. It may allow us to implement drastic measures without collapsing the economy and give us time to cope with the change.




Introduction to collapse

The nature of complex societies
Nature of complexity
Simple societies
Levels of complexity
The evolution of complexity

The study of collapse
Resource depletion
Insufficient response to circumstances
Economic explanations

Understanding collapse: the marginal productivity of sociopolitical change
Diminishing returns on investments in complexity
Agriculture and resource production
Information processing
Sociopolitical control and specialisation
Overall economic productivity

Evaluation: complexity and marginal returns in collapsing societies
The collapse of the Western Roman Empire
The Classic Maya collapse
The Chacoan collapse

Summary and implications


Introduction to collapse

Throughout history, there has been a universal trend towards higher levels of complexity, specialisation, and sociopolitical control, the processing of larger quantities of energy and information, the formation of larger settlements, and the development of more complex and capable technologies. This trend has been interrupted by instances of collapse.

A society or civilisation has collapsed when it displays a significant loss of an established level of sociopolitical complexity. To qualify as collapse, it must have been or was developing toward a level of complexity for more than two generations. The breakdown must be rapid and take no more than a few decades, and it must entail a substantial loss of sociopolitical structure. Collapse consists of many kinds of processes.

According to Tainter, collapse is a political process with consequences for other areas like the economy and the arts. It manifests itself in:
  • a lower degree of stratification and social differentiation
  • a reduced economic and occupational specialisation of individuals, groups, and territories
  • less centralised control; that is, less regulation and integration of diverse economic and political groups by elites
  • less behavioural control and regimentation
  • less investment in monumental architecture, art and literature
  • a reduction in information flows between individuals, political and economic groups, and between the centre and its periphery
  • less sharing, trading, and redistribution of resources
  • less overall coordination and organisation of individuals and groups
  • political units cover smaller territories

  • Collapse is a general process not restricted to a type of society or level of complexity. Complexity is a continuous scale. Collapse must be considered relative to the size of the polity where it occurs. Tribes and chiefdoms can lose an established level of complexity just as great empires. A region under a chiefdom may lose its hierarchy and revert to feuding villages. A group of foragers may be so distressed by environmental degradation that they abandon their social organisation.

    After a collapse, there is a breakdown of authority and central control. Government revenues decline, the former political centre loses its prominence and power. Petty states emerge. Law and order disappear. Local self-sufficiency replaces trade and craft specialisation reduces. Populations decline. No longer can people rely on external defence or internal order, maintenance of public works, or delivery of goods.

    The nature of complex societies

    Nature of complexity

    Complexity refers to the size of a society, the number and distinctiveness of its parts, the variety of specialised occupations, the number of distinct social roles, and the number of mechanisms for organising these into a coherent functioning whole. Hunter-gatherer societies contain only a few dozen distinctive social roles. Modern European censuses recognise 10,000 to 20,000 unique occupational roles.

    Two concepts to understanding the nature of complexity are inequality and heterogeneity. Inequality is vertical differentiation, ranking, or unequal access to material and social resources. Heterogeneity is the number of distinctive parts in society and how the distribution of the population among these parts. A population is homogeneously distributed when divided equally among the occupations and roles in society. The converse brings increasing heterogeneity and complexity. Inequality and heterogeneity are interrelated but respond to different processes and are not always positively correlated.

    Complex societies are decomposable if they consist of social units that are themselves potentially stable and independent and at one time may have been so. A newly established state may include formerly autonomous villages, and an empire may incorporate previously established polities. To the extent that these villages and states have retained the potential for independence and stability, collapse may result in a reversion to these building blocks of complexity.

    During the last 6,000 years, hierarchical, organised, interdependent states emerged. Complex societies tend to expand and dominate so that today they control most of the earth’s land and people. The most common political unit was the small autonomous community acting independently. These small communities were homogeneous and organised based on kinship. The degree of variation in size, complexity, ranking, and differentiation between these societies was substantial.

    Simple societies

    Simple societies have minimal leadership. It is personal, charismatic, and exists only for specific purposes. Equality in these societies comes from the individual access to the resources to sustain life. Social rules constrain leaders from exercising authority, amassing wealth, or acquiring excessive prestige. Personal political ambition is either restrained from expression or channelled to fulfil a public good. To achieve the elevated position of Big Man, an ambitious individual must acquire a surplus of subsistence resources and distribute them in the community. In this way, he can establish prestige in the community and create a following.

    When several ambitious individuals do this, there is competition and jockeying for position. A Big Man strives to create a following but is never permanently successful. His influence is limited to his faction, so expanding his influence means extending the size of his following. At the same time, he must constantly renew the loyalty of his existing followers through generosity. Big Man systems thus have a structural limit on scope and durability.

    Other simple societies are organised at higher levels of political differentiation in chiefdoms with permanent ranks. These ranks are often hereditary. There is a lot of inequality in such societies, which usually are larger and more densely populated. There is a political economy in which rank conveys the authority to direct labour and economic surpluses, for instance, to engage in public works. Economic specialisation, exchange, and coordination exist. Family politics limits the authority to command. Furthermore, there is no monopoly of force but only a marginal advantage.

    Chiefly generosity is the basis of politics and economics. The downward distribution of amassed resources ensures loyalty. Chiefly ambitions, like those of Big Men, are thus structurally constrained. Too much allocation of resources to the chiefly apparatus, and too little return to the local level, meets resistance. Hence, chiefdoms undergo cycles of centralisation and decentralisation, much like Big Man systems. Chiefdoms have many similarities with states but fall within the category of simple societies because of limits posed by the obligations of kinship and the lack of true coercive force.


    States differ from tribal societies in several ways. They have a territorial organisation, membership is based on residence rather than real or fictive kin relations, and in states, the ruling authority monopolises sovereignty and delegates all power. The ruling class tends to be professional and is largely divorced from the bonds of kinship. The ruling class supplies the personnel for government, which is a specialised decision-making organisation with a monopoly of force. A society-wide ideology exists, in part, to justify the political organisation of society.

    Emile Durkheim recognised that the evolution from primitive to complex societies entails switching from mechanical solidarity to organic solidarity. Mechanical solidarity comes from shared values and beliefs that work internally in individual members, while organic solidarity arises out of the need of individuals for each other's services. Mechanical solidarity comes with homogeneity, a lack of cultural and economic differentiation among the members of society. Organic solidarity entails heterogeneity and cultural and economic differentiation requiring interaction and cohesiveness.

    Rulers of states still need to establish and constantly reinforce their legitimacy. Legitimacy is the belief of the populace and the elites that the rule is proper and valid and the political order is as it should be. A regime can only survive with the support of the population. Coercion is costly and can never be permanently successful. Establishing moral validity is cheaper and more effective.

    Complex societies have a centre, which is the symbolic source of the framework of society. It is the location of legal and government institutions, but it is the source of order and the symbol of moral authority and social continuity. The centre is sacred. In this sense, every complex society has an official religion. One critical impediment to the development of complexity in stateless societies is the need to integrate many localised autonomous units, which could each have their peculiar interests, feuds, and jealousies. When a ruler comes from one of these units, people from other areas will fear favouritism.

    Linking leadership to the supernatural can overcome this limitation. When a leader has an aura of sanctified neutrality, a ritually sanctioned authority can supersede his identification with a natal group. Supernatural sanctions are thus a response to the stresses of change from a kin-based society to a class-structured one. A lack of coercive force may require such an arrangement. As soon as coercive institutions emerge, the need for religious integration declines, and a conflict between secular and religious authorities may ensue. The sacred aura remains a critical element in maintaining legitimacy, even in contemporary secular societies.

    Leadership support must have a material basis. Legitimacy declines in the case of output failure, which is a situation in which authorities fail to meet the demands of the support population or do not take anticipatory actions to counter adversities. Output expectations are continuous. They impose on leadership a never-ending need to maintain support. It requires the commitment of resources and is a cost to complex societies.

    Levels of complexity

    Anthropologists have typologies of societies based on complexity. The details of these classifications are not pertinent to understanding collapse, but their underlying assumptions and philosophy are. A typical categorisation is bands, tribes, chiefdoms, and states. A classification eliminates information about variety but produces information about similarities. The distinction between state and non-state is the most interesting, and anthropologists see it as the great divide of history. States are characterised by:
  • territorial organisation
  • differentiation by class and occupation rather than kinship
  • monopoly of force
  • authority to mobilise resources and personnel
  • legal jurisdiction

  • There is often no discontinuity between state and non-state societies regarding these characteristics. The development of complexity is a continuous variable, and so is collapse. It is a decline in complexity. Not using a typological approach allows for researching a range of social transformations. Prime examples are the development of complex chiefdoms and periodic reversions to smaller chiefdoms, and the collapse of societies that never were a state.

    The evolution of complexity

    The factors that lead to complexity are pertinent to understanding collapse. The emergence of complex social institutions and their failure are intertwined. Much about the origins of complex societies remains controversial. There are several lines of thought on the reasons for the first states to emerge (primary state formation). These are:
  • Managerial. As societies come under stress or populations increase, integrative requirements arise that only hierarchies can manage.
  • Internal conflict. Class conflict is the primary driver of complexity as the state emerged to protect the privileges of those with preferred access to resources.
  • External conflict. Stresses in bounded environments lead to conflict. Success at war necessitates the development of institutions to administrate conquered groups.
  • Synthetic. Several interrelated processes generate complexity and state institutions.

  • States are dominating and expansive organisations. They have a competitive advantage over less complex social forms. They tend to spread and stimulate similar developments among their neighbours. The emergence of complexity among competitors and trade partners of states is called secondary state formation.

    There are two principal schools of thought about states. These are conflict and integration (functional). The conflict view holds that states emerged to resolve intra-societal strife caused by economic stratification. They exist to maintain the privileged status of the ruling class. Marxism falls into this category. Marxism claims that production is the basis of society. The technical and social relations of production determine the sociopolitical organisation of society, which are the relations of appropriation between classes.

    Integration theories suggest that complexity and stratification arose out of the needs of a population. The integration view holds that there are shared rather than divided social interests, common advantages instead of dominance and exploitation, consensus not coercion, and societies being integrated systems rather than stages for power struggles. Complexity might arise as a response to:
  • circumscription and warfare in a limited, stressed environment
  • the need to process increasing amounts of information from ever more sources
  • the need to mobilise labour for public works and managing critical resources
  • the need for regional integration of specialised local economies
  • the need to import essential commodities

  • Both schools have strong and weak points. Since greed, oppression, exploitation, and class conflict are characteristics of complex societies, it is tempting to see them as a source of complexity. This view is not without merit, but complex societies do not arise solely from political goals. It is psychological reductionism to explain the emergence of the state out of the desires and needs of a small privileged group. There is a supposed universal tendency for self-aggrandisement. When survival requires egalitarian cooperation, people do not tolerate hoarding and self-aggrandisement. That is often the case in simpler societies. Individual ambition has benefits in some situations, while it causes problems in others.

    In integration theory, the benefits for those who fulfil society’s administrative roles are compensation for performing socially crucial functions. The cost of stratification is a necessary evil to realise integrative advantages. In basing the benefits of complexity on real observable needs, integration theory avoids psychological reductionism. Expression of ambition is a social variable rather than an independent psychological constant. However, the costs and benefits of social stratification are often not balanced, and the compensation for elites often does not reflect their contribution to society. Coercion and exploitative regimes are undeniable facts of history. And, governing bodies that provide goods or services have coercive power because they can withhold them. And so, coercion accompanies benefit.

    Legitimacy affects both views. If elites must rely on force to ensure compliance, the cost of coercion will consume much of their profit. All ideologies have the assumption that a government serves the common good. Some delivery on this promise is essential. Legitimising activities must include genuine outputs. Conflict and integration theory on their own are inadequate to account for the origin and the persistence of states. Integration theory better accounts for the distribution of the necessities of life, and conflict theory for the surpluses. Self-aggrandisement does not explain the development of states, but it helps to understand their history. In both views, states are problem-solving organisations. Both views see the state as a response to changing circumstances. The nature of complex societies as problem-solving organisations has much to do with understanding their collapse.

    The study of collapse

    Ancient and medieval writers saw collapse as the fall of political entities. Social scientists think of the end of a civilisation as a transformation of the features and behaviours that characterise a cultural entity, for instance, art, architecture, literature, and music. The rise and fall of civilisations do not correspond closely to specific polities or events. This view is problematic because the term civilisation is vague, and there is an element of unscientific value judgement in the concept. Usually, there is a lot of continuity in cultural behaviour when one civilisation ends and makes place for another. And cultures change continuously, so a transformation to a new civilisation is difficult to pinpoint. The question of value judgements is equally significant. What distinguishes civilised societies from uncivilised ones?

    Seeing civilisations as large and complex cultures is more fruitful. For this study, civilisation is the cultural system of a complex society and consists of social, economic, and political complexity. Civilisation thus emerges with complexity, exists because of it, and disappear when complexity does. Polities can rise and fall within a civilisation, but political complexity must disappear for civilisation to disappear. Explanations of collapse fall in the following categories:
  • depletion of vital resources on which a society depends
  • the establishment of a new resource base
  • an insurmountable catastrophe
  • insufficient response to circumstances
  • other complex societies
  • intruders
  • class conflict, societal contradictions, elite mismanagement or misbehaviour
  • social dysfunction
  • mystical factors
  • chance concatenation of events
  • economic factors

  • Resource depletion

    There can be deterioration or depletion of a resource base, often because of human mismanagement, or a rapid loss of resources due to environmental fluctuation or climatic shift. For instance, scientists have argued that climate change leading to resource insufficiencies stimulated the barbarian migrations that devastated the Roman Empire. Another explanation is that political stability, road networks, and centralised administration created a situation where local food shortages could be alleviated to a greater degree, promoting surplus production and population increases. It led to greater demands on agriculture and land exhaustion.

    Resource depletion arguments appear attractive because societies need a resource base, but they often presume that they do not take action to deal with them. Dealing with resource uncertainties is a habitual activity of complex societies and often a reason for their existence. They have centralised decision making, information flows, coordination of parts and pooling of resources. If they fail to deal with resource depletion, their characteristics may prevent an appropriate response.

    Insufficient response to circumstances

    This explanation assumes that complex societies are inherently fragile, static, or incapable of shifting directions because of fundamental limitations of social, political, and economic systems. Evidence does not support this. There are several views and models used in this reasoning.

    One view is that self-sufficiency and autonomy of local systems reduce as specialisation increases, causing instability. Another opinion holds that early empires have room to optimise their resource allocation, but in doing so, they become inflexible. Success can breed conservatism. The Law of Evolutionary Potential states that the more specialised and adapted a form is to a given environment, the less able it becomes to accommodate change.

    Another model suggests that simpler societies have a concentric organisation that extends from the individual to ever-widening spheres, such as family, village, and tribe. In concentric communities, the elites impose intergroup connections from above. As change is not in the interest of the ruling classes, and there is a lack of common interest between groups, there is no mechanism for gradual adjustment to changing circumstances.

    Various explanations exist for the collapse of the Roman Empire, such as economic stagnation and lack of lower- and middle-class incentives, large estates using slave or serf labour, lack of regional economic integration, taxation and the cost of government, a weak financial system limited by minimal credit and the supply of precious metals, and the end of geographical expansion.

    Researchers have claimed that the Mayan population and sociopolitical complexity increased in lockstep. State control over the economy led to greater efficiency in the production and distribution of food. That subsequently led to larger populations requiring more managerial control. Measures to increase food production then stretched the environment to the breaking point.

    Some have come up with an explanation for the weakness of the Aztec and Inca empires. Ideologies that were beneficial in the early history of empires became maladaptive later on. For the Aztecs, it was human sacrifice and required military expansion to acquire the victims. A new Inca emperor did not inherit property. As rulers ascended to the throne without an endowment, new conquests were necessary.

    These views acknowledge that the characteristics of societies cause collapse, and they fall into the following categories: the dinosaur model, the runaway-train model, and the house-of-cards model. The dinosaur model sees a complex society like a colossus incapable of rapid change. The runaway-train model implies that complex societies cannot change direction, remain static, or regress. That may be due to positive feedback mechanisms. The house-of-cards model suggests that complex societies are fragile as a rule and bound to collapse.


    The theme is antagonism and conflicting goals between social classes. Elite mismanagement or self-aggrandisement can prompt the populace to withdraw support or revolt. The fourteenth-century Arab historian Ibn Khaldun developed a cyclical theory of history. According to him, dynasties run their course in three to four generations as leaders become increasingly addicted to luxury and security. They raise taxes to pay for this. When taxes are low, the population is more productive. And so, the tax yield is higher. As taxes increase, productivity declines, and the polity cannot fund itself anymore.

    Another cyclical theory is that barbarians first rise to civilisation and then decline into barbarism again. The factors responsible are changing relations between elites and the populace, class conflict, and pursuit of self-interest. In civil society, discord fanned by demagoguery leads to abandonment of civic responsibilities and the pursuit of individual goals. That, in turn, leads to barbarism.

    Political scientists made similar points. The difficulties in empires tend to be pressure on resources caused by the extravagance of the elites, faulty administration in dealing with concrete problems, the distribution of power among groups and regions, and crises in relations between rules and elites or competition between elites. Rulers often implement policies to address immediate financial or personnel needs to the detriment of future economic development. As resources become depleted and the peasantry alienated, rulers increase taxes and delegate power to local authorities. Consequently, feudal systems emerge that undermine central authority.

    Some researchers attributed the Mayan collapse to peasant revolt or competition between polities leading to population growth, over-taxation, and destructive wars.

    Chinese political thought has long seen conflict and mismanagement as the sources of dynastic collapse. All dynasties began with prosperity and peace and bringing new land into production. They built roads, canals, palaces, and walls and maintained costly defence lines. But as imperial relatives, nobility, and the bureaucracy increased in numbers and grew accustomed to luxury, the ruling class used more resources, so less remained for administration. Increased expenditures and declining revenues caused dynasties to experience financial difficulties within a century after their founding. Official self-serving and corruption would worsen, administrative efficiency would deteriorate, and factional quarrels at the court would increase. The burden on the peasantry increased while dikes and canals went into disrepair. Famines previously met from government granaries began to cause starvation, banditry, and peasant uprisings. Frontiers become inadequately defended, and provincial officials and their armies defect. The resulting wars clear the slate for a new dynasty.

    Researchers have attributed the collapse of Rome to decadence, growth in bureaucracy, excessive taxation, a decline of martial spirit, ignorance of dangers, and poor leadership. Another explanation is that large slave estates replaced free peasants and that the landed gentry accepted monarchy for personal safety, which may have caused a demoralisation of the exploited classes.

    An explanation for the decline of the Byzantine Empire in the eleventh century is the rise of a landed aristocracy. The empire depended on free peasant soldiers for its defence. As great landowners absorbed small landholdings, free peasants disappeared. Conflicts between the emperor and the rising aristocracy brought civil wars. It drained resources at a time when new enemies appeared. The empire adopted a mercenary army, and the overtaxed peasantry lost concern for the state.

    Others argued that the poor in the cities who were on the dole and the army had eaten up the capital of the thrifty and that civilisation did not reappear until the thrifty and energetic could again safely use their abilities in wealth-producing activities. Conflict theories thus have appeal to Marxists and capitalists alike.

    The objections to conflict explanations for collapses mirror those for increasing complexity. The administrative capacity to control labour and allocate resources allows complex societies to deal with natural and social adversities. Both the population and the elites benefit from this. Conflict theories must acknowledge that any rational dominant class, however oppressive, must make some provision for the welfare of the populace on which they rely out of self-interest. Elite mismanagement and self-aggrandisement, if they are detrimental to the survival of a society, are matters to be explained. Exploitation and mismanagement are normal, regular aspects of complex societies and cannot explain collapses. Peasants are frequently disaffected, but they rarely revolt.

    Economic explanations

    Economic explanations often come down to declining advantages of complexity, increasing disadvantages of complexity or increasing costliness of complexity.

    The Ottoman Empire began to fall behind in military, administration, labour force, revenue, and resources. European expansion made the eastern Mediterranean an economic backwater, and the region became impoverished. The inflow of gold from the Spanish American colonies ruined the Ottoman economy. Against the background of economic weakness, the government had to expand its salaried personnel and expenditures in coin. Consequently, civil, religious, and military personnel experienced more difficulty making ends meet, with inevitable effects on honesty, prestige, and recruitment. As the bureaucracy became more inefficient and venal, the effectiveness of the tax system declined. As a result, the shrinking economy of the empire had to support an increasingly costly and cumbersome state.

    Economic explanations can be superior if they identify characteristics of societies that make them liable to collapse, specify controlling mechanisms, and indicate causal chains between these controlling mechanisms and observed outcomes.

    Other explanations

    New resources. New bountiful resources may cause complexity to disappear if it existed to deal with resource stress. It affects simple societies the most.

    Catastrophes. Complex societies regularly provide for disasters and routinely experience them without collapsing. When a society cannot weather catastrophe, its characteristics are often of greater interest.

    Other complex societies. It does not provide a satisfactory explanation for cases in history. Conflicts between states often lead to expansion and contraction rather than collapse.

    Intruders. The overthrow of a dominant state by a weaker one is an event to be explained, not an explanation in itself. Intruders are often difficult to detect in the archaeological records where they were supposed to have been.

    Social dysfunction. These explanations offer neither sources of strain nor causal mechanisms for objective analysis.

    Mystical. Mystical explanations contain no reference to empirically knowable processes and often introduce value judgements. They rely on concepts like decadence, virtue, vigour, and senility. Often biological analogies are used. For instance, all things must decay. Other explanations are the disappearance of great men or the introduction of democracy so that the poor take the money from the wealthy. Mystical explanations do not scientifically account for collapses.

    Chance concatenation of events. This theme provides no basis for generalisation. Random factors cannot explain collapses.

    Understanding collapse: the marginal productivity of sociopolitical change

    Diminishing returns on investments in complexity

    Human societies and political organisations require a continuous flow of energy. Energy flow and sociopolitical organisation are interdependent. Neither can undergo substantial change without altering the other and the balance between them. The amount of energy must be sufficient to support the complexity of the sociopolitical system. More complex societies are more costly to maintain than simpler ones, requiring greater support levels per capita. As complexity increases, more networks emerge among individuals, more hierarchical controls are installed to regulate these networks, and more information is processed. There is more centralisation of information flows, and there is an increasing need for support specialists not directly involved in resource production.
    The law of diminishing marginal returns
    The law of diminishing marginal returns

    In the conflict view and the integration view, complexity is a response to perceived problems. Its facility to resolve these problems is part of a ratio of benefits to investments. In many crucial spheres, the benefits of continued investment in sociopolitical complexity will at some point start to decline. Two concepts matter here. The average product is the output per unit of input. The marginal product is the increase of total output coming from one additional input. Similarly, the average cost is the cost per unit of input, and the marginal cost is the increase or decrease in total cost resulting from one more or less unit of output.

    The law of diminishing returns states that average product and average cost respond to, and ultimately follow, changes in marginal product and cost. The marginal return is the return per increased unit of investment. The increased cost of sociopolitical evolution frequently reaches a point of diminishing marginal returns. Complexity becomes increasingly costly and yields decreasing marginal benefits.

    The following concepts can help us to understand why complex societies collapse:
  • human societies are problem-solving organisations
  • sociopolitical systems require energy for their maintenance
  • increased complexity comes with increased cost per capita
  • investment in sociopolitical complexity as a problem-solving response often reaches a point of declining marginal returns

  • Agriculture and resource production

    It can be helpful to break down complexity into several constituent parts and examine them individually. These parts are agriculture and resource production, information processing, sociopolitical control and specialisation, and overall economic productivity. In 1965, the economist Ester Boserup claimed that increasing intensity in agricultural use of land comes from labour investments that are disproportionately greater than the returns received. The productivity per unit of land increases, for instance, by fertilisation and irrigation, but the productivity per unit of labour decreases. Boserup identified the following types of land use:
  • Forest-fallow cultivation, also known as swidden, milpa, or slash-and-burn, is a system in which plots are cleared in forests and planted for several years. As weeds encroach and yields decline, farmers abandon the land until the forest has fully returned. The fallow period may be as long as 25 years.
  • Bush-fallow cultivation employs a shorter fallow of six to ten years.
  • Short-fallow cultivation comes with a fallow of one or two years.
  • Annual cropping comes with a few months between harvest and next planting.
  • Multi-cropping is the most intensive system of land use. It is possible in a few regions where the climate is favourable.

  • An expanding population inevitably strains each form of land use. That forces a shift to a more intensive type of agriculture. As a result, the productivity of labour decreases.

    Animal husbandry follows the same pattern. The labour-intensive nature and costliness of animal husbandry are well known. The canals and railways built in England during the Industrial Revolution reduced the competition between people and horses for the produce of the land. Between 1850 and 1910, there were no major technological breakthroughs in the dairy industry. There were other changes like extending dairying into the winter months, improvements in feeding, and stricter sanitary requirements. Between 1850 and 1910, dairy output per unit of labour declined.

    Energy and minerals production follows the same productivity curve as subsistence agriculture. The resources used first are the most abundant, most accessible, and most easily converted to the needs at hand. When it becomes necessary to use more expensive resources, marginal returns decline. England witnessed jumps in population around 1300, around 1600, and in the late eighteenth century, each leading to the intensification of agriculture and industry.

    As the land became increasingly deforested in the late Middle Ages to provide fuel and agricultural space for an increasing population, there was not enough wood left for heating, cooking, and manufacturing needs. A gradual and reluctant switch to coal began. Mining coal was more costly than obtaining a quantity of wood with equal heating value. It became even more expensive after the depletion of the most accessible coal reserves. Mines became deeper. Groundwater flooding became a serious problem. The first steam engines pumped water out of the mines. The process of declining marginal returns to energy investment is continuing.

    Information processing

    Processing large quantities of information is an essential aspect of complex societies and one of the reasons that they came into existence. Investments in information processing often show declining marginal productivity. As the size of a social group increases, the communication load increases faster. Information processing increases in response until reaching capacity. After this point, information processing performance deteriorates, and less efficient and reliable processing comes with higher costs. At this point, information processing hierarchies may develop.

    Moore suggested that, as the amount of information increases, the marginal cost of attaining useful information increases rapidly, partly because redundancy increases. Areas of information processing are research and development, education, and the maintenance of information channels.

    General education has the most lasting and widespread value. Specialised training is costlier and builds on the former, and the learning that occurs yields decreased benefits at higher costs. The situation in research and development is similar. Specialised scientific knowledge depends on general principles and builds upon them. Science is not entirely cumulative. Rethinking or rejection of earlier work is commonplace.

    The decreasing benefits from specialised derivative work come at substantially higher costs. The cost to societies of early science was minimal. It often consisted of supporting individual naturalists and mathematicians. Science today is a costly process involving complex institutions, sophisticated technology, and large, interdisciplinary research teams. The marginal productivity of research and development in the United States declined significantly as the ranks of scientists, engineers and technicians increased. The effects of spending on medical research on life expectancy are also decreasing. Science today researches difficult-to-solve questions, and with every answer found, the costliness of solving the remainder increases. It is also applicable to archaeology. For a good part, this explains the declining productivity of research and development.

    Sociopolitical control and specialisation

    Complex societies feature a recurrent inexorable trend of declining marginal productivity in hierarchy and specialisation. Politicians rally voters against it. C. Northcote Parkinson conjured a vision of bloated bureaucracies growing ever larger, devouring more taxpayer resources, and producing ever less real value. He suggested that, beyond a certain point, increasing taxation yields declining marginal returns.

    Parkinson claimed that bureaucratic self-serving is to blame. That is too simplistic. A similar trend exists in private organisations. In the private sector, economic success depends on efficiency. And so, this pattern cannot be attributed to self-serving inefficiency. The reason is that increased complexity requires more information processing and greater integration of disparate parts.

    Control and specialisation are at the essence of complex societies. The reasons why investments in complexity yield a declining marginal return are the increasing size of bureaucracies, increasing specialisation of bureaucracies, the cumulative nature of organisational solutions, and growing costs of internal control and external defence. These spheres are intertwined.

    Human social evolution has proceeded from lower to higher complexity. More complex social forms require more support costs per capita. A common trend among human organisations is to respond to problems by developing specialised administrators and increasing the proportion of the population engaged in administrative tasks. At some point, this will yield no benefits. Organisational solutions tend to be cumulative. Once developed, complex features usually remain in existence. For instance, an ever-growing stock of monuments needs maintenance.

    Complex societies tend to experience cumulative organisational problems. As systems develop more parts and more complex interactions, the potential for difficulties, conflicts, and incongruities increases disproportionately. With new regulations and taxes, people seek loopholes, and regulators strive to close them. There is an increased need for specialists to deal with such matters. A spiral of loophole discovery and closure might follow with complexity and cost increases. In technological systems, the potential for catastrophic accidents increases with complexity, and the cost of preventing them rises.

    Complex hierarchies must allocate resources to solving problems of the population it administers, problems created by its own existence and problems caused by the complexity of society itself. To maintain growth in complexity, hierarchies levy higher taxes, but at some point, this yields declining marginal returns. Rulers must constantly legitimise their reign. Legitimising activities can be external defence, maintaining internal order, alleviating the effects of local productivity fluctuations, undertaking development projects, and providing food and entertainment for urban masses. Whatever activities a hierarchy initially undertakes to bond a population, for instance, public works or bread and circuses, it becomes a custom, so further bonding comes at higher costs without additional benefits to the hierarchy. The appeasement of urban mobs is a classic example.

    In Rome, bread and circuses became an expected minimum. Increased investment in bread and circuses, which seemed necessary to legitimise new rulers, did not improve returns beyond non-revolt. Rewards to Roman military personnel often followed the same pattern. Soldiers received bounties upon a ruler’s accession. Roman soldiers regarded such bounties as a right. The alternative course is to reduce legitimising activities and to increase other means of control, but the marginal cost of coercion at some point increases, and the marginal return declines.

    Overall economic productivity

    Complex societies with well-developed economies have relatively low rates of economic growth. It appears that in developed economies, the productivity of investments tends to decline. Technological innovations often occur along a curve of declining marginal productivity. An example is the reduction of fuel consumption of steam engines. When efficiency increases, the remaining possibilities for savings reduce. A possible explanation is that the upkeep of existing capital stock limits investment in growth or that the same amount of economic growth requires more and more investment, for instance, in research and development.

    Evaluation: complexity and marginal returns in collapsing societies

    The shift to increasing complexity, undertaken initially to relieve stress or realise an opportunity, begins as a rational and productive strategy that yields a favourable marginal return. Usually, stress, unanticipated challenges, and the costliness of sociopolitical integration lower this marginal return. As a result, complexity yields declining benefits at increasing costs. A society that cannot counter this trend becomes vulnerable to stress surges that it is too weak or impoverished to meet and waning support in its population. With the continuation of this trend, collapse becomes inevitable. Over time an insurmountable stress surge becomes increasingly probable. Until this happens, there may be a period of economic stagnation, political decline, and territorial shrinkage.

    The collapse of the Western Roman Empire

    The collapse of the Western Roman Empire cannot be attributed solely to an upsurge in barbarian incursions, economic stagnation, civil wars, or vague processes like a decline of civic responsibility, the spread of Christianity, or poor leadership. Several of these factors were involved in the process. Understanding the process requires going back in time to the formation of the empire. There was a tendency among Romans to migrate to newly conquered territories. It is unclear whether opportunities, perceived threats, policy, or demographic pressure made this happen.

    And so, there were pressures favouring a policy of territorial expansion. This policy was at first highly successful. The conquered provinces brought in loot, tributes and taxes. When the Romans seized the treasury of the king of Macedonia in 167 BC, they could eliminate taxes on themselves. New conquests increased the state budget as gold and silver flowed in, so they were economically self-perpetuating. Previous victories provided the economic base for further conquests. It culminated with the capture of Egypt when the booty allowed the emperor to distribute money to the plebeians of Rome. The expansion ended after losses to the Germans. The empire then concentrated on maintaining the army and restoring the prosperity ruptured by civil wars.

    With the end of the expansion, there was a corresponding drop in the windfalls of conquest, and the first fiscal shortages began to emerge. The principal imperial costs were wages, rations and fodder for the army, the civil service, and other state employees, which were in later times workers in the imperial arms factories, public works, postal service, and the public dole. The largest expense was the military, although the dole was significant. Around 200,000 heads of families received free wheat. A special fleet was needed for transport, as were wharves on the Tiber River, the port of Ostia, and numerous shipowners and bakers. Despite the stagnation of revenues, there were clear benefits to the early empire. It provided foreign and internal peace and security, defended borders, protected commerce, and undertook public works. The early empire was prosperous even when the state had fewer resources.

    The Roman economy was overwhelmingly agricultural. Trade and industry were insignificant. One of the main reasons was the high cost of transport. A wagon load of wheat would double in value with a land journey of 480 kilometres. Land transport was so costly and inefficient that it was often impossible to relieve inland famines. Ship transport was much more economical. It allowed the empire to rely on Egypt for food production. The taxing system was inflexible, and the state did not borrow. At first, the state income grew from 500,000 sesterces under August to 1,200,000 under Vespasian (69-79 AD), but expenses increased faster. Wars were costly. Between 165 and 180 AD, a plague reduced the available labour force for agriculture and the army. Emperors faced with an insolvent government often debased the silver denarius. The cities lacked revenue. Elected officials came from the local wealthy classes, and they had to finance all or part of the duties of their office. These expenditures increased over time and became so burdensome that candidates for office began to fall off.

    From 235 to 284 AD, the Roman Empire faced a crisis and nearly collapsed. There were foreign and civil wars, barbarian incursions, the devastation of many provinces, size increases of the army and the bureaucracy, financial distress and increased taxes, currency debasement and unparalleled inflation. Emperors had short reigns averaging only a few months. Education became reduced to rhetoric. There was an increase in mysticism, which is knowledge by revelation. The barbarians were unskilled in siege warfare and concentrated on the countryside. They destroyed crops, seized cattle, and took the population into slavery. Roman armies were almost as destructive. Inflation sapped the value of military compensation, so army units were often forced to seize what they needed from the local population. The ravaging of the countryside and a new plague between 250 and 270 AD caused the rural population to decline even further.

    The wealthy continued to do well. Large landowners emerged in increased numbers in all parts of the empire during the third century. In the towns, the middle class faced increasing costs of civil obligations. Small peasants lost their holdings and became tenants in large estates. Commerce declined because the countryside and the seas became increasingly unsafe. The survival of the Roman Empire was at stake. Emperor Aurelian pushed back the barbarians, reattached rebellious provinces, and started reforms like conscripting labour when needed for the walls of Rome. He also ordered deserted lands to be obligatorily farmed under the direction of local city senates. The effect was that peasants and villagers had to work in enlarged agricultural labour forces.

    Emperor Diocletian, who reigned from 284 to 305, introduced reforms that changed the nature of the empire and allowed it to survive for a while longer. The state that emerged in the fourth century was vaster, more complex, more highly organised, and commanded larger, more powerful military forces. It taxed its citizens more heavily, conscripted their labour, and regulated their lives and occupations. It subdued individual interests to levy resources to the survival of the state. Diocletian split up the empire so that there were four emperors. He increased the number of provinces so that governors could not rebel. As a result, the size of the bureaucracy became greatly expanded.

    State factories provided for the arms of the military and the needs of the court. Even though the number of usurpers and civil wars declined, emperors still felt the need to spend on public display to legitimise their reigns. The building of Constantinople and the dole were a drain on the state’s finances. Inflation was rampant, so Diocletian imposed price controls in the Edict of Prices of 301. Emperors debased the coinage for everyday commerce, for this was the currency used by the government to meet its military obligations. Gradually, more gold solidi came into circulation, and inflation stopped in the fifth century.

    The increases in military strength and civil administration had to be supported by a depleted population. There was a decline in personnel available for agriculture, industry, the army, and the civil service. Agriculture and industry declined accordingly. The military increasingly enlisted barbarians while barbarian colonies emerged in depopulated lands under Roman rule. Conscription became a regular practice, and families became tied to essential occupations. Agricultural labour became bound to the soil. It created a system of serfdom with tenants tied to large estates. It was a boon to large landowners facing labour shortages.

    Arable land became abandoned because of labour shortages, barbarian invasions, and high taxes. In the sixth century AD, landowners paid two to three times as much in taxes than in the first century BC. The tax burden did not allow peasants to build reserves, so in the case of adversity, they had to hand over their lands to their creditors. People who could not pay their taxes ended up in jail while their children became slaves. In the case of famine, peasants suffered the most, and they often flocked to the cities that held stores of grain. Cities suffered too. In Gaul, cities contracted.

    There were rigid output controls. Each citizen, guild, and locality had to produce specified essentials for the state's survival. For a time, this strategy worked, but at the cost of land abandonment, lower agricultural yields, and impoverishment of the cities. Many citizens hoped that the barbarians would free them from the burden of empire. The dwindling labour supply and wealth helped the invaders, and their successes eroded the imperial finances.

    The Roman expansion was a strategy with declining marginal returns. Over time, the number of profitable conquests declined. The remaining areas were either unattractive or occupied by other strong powers. The logistics of transport and communication made it difficult to govern remote lands. Once the empire had spent the surpluses of conquests, it had to pay the expenditures for administration and garrisons in the provinces out of current income. Costs rose while benefits declined. Lands that first were a windfall became a burden.

    The empire's weaknesses exposed by the confrontation with the Marcomanni under Marcus Aurelius between 166 and 180 AD proved nearly fatal during the subsequent crisis. The reduced marginal return on organisational investment left the Roman Empire without reserves to meet such emergencies. The only alternatives were raising taxes and currency debasement. The crisis of civil war and barbarian incursions required increased expenses that yielded no increased return. The empire did not expand, no major booty came in, and agricultural output did not improve. Hence, the marginal return on investment in the state declined. The costs of saving the empire became extraordinarily high for a non-industrial population. These costs came without increased benefits.

    When a complex society enters a situation of declining marginal returns, collapse can come from a lack of sufficient reserves to meet stress surges and alienation of the overtaxed population. A portion of the peasantry welcomed the barbarians. Many others were apathetic to the impending collapse. The empire had lost its legitimacy. In the face of the barbarian successes, its protection proved increasingly ineffectual. To many, there were no remaining benefits to the empire, as both barbarians and Roman tax collectors ravaged their lands. The collapse reduced the cost of complexity and increased the marginal return on investment in state power. The smaller Germanic kingdoms that succeeded the Roman Empire were more successful in resisting foreign incursions of Huns at lower costs. Prosperity in North Africa rose under the Vandals and declined under Justinian’s conquest when he reimposed imperial taxes.

    The Eastern Roman Empire had a larger economy and was strategically less vulnerable. The provinces were better able to bear the costs of defence and administration. Estimates indicate that the budget of the West was only 1/3 of the East while the West had over twice as long a northern frontier to defend. While invaders overran the West, the East faced only serious trouble at the Danube. Investment in complexity was easier to finance, while the support population could afford higher taxes.

    The Classic Maya collapse

    The disappearance of the Classic Maya Civilisation in the Southern Lowlands in Guatemala is a puzzle. It collapsed between 790 and 890 AD. The area is currently a rainforest. It was also the case when the Maya began to cultivate the land. The characterisation of the Mayan archaeological chronology is as follows: Middle Preclassic (1000-400 BC), Late Preclassic (400-50 BC), Protoclassic (50 BC-250 AD), Early Classic (250-550 AD), Hiatus (550-600 AD), Late Classic (600-800 AD), Terminal Classic (800-1000 AD), Post Classic (after 1000 AD). The mystery of the collapse is due to misconceptions about the nature of this civilisation.

    The first villages emerged around 2000 BC. The Middle Preclassic and Late Preclassic farmers were successful as the population increased. At some point, population growth led to strains on existing food production systems. Several responses followed. Agriculture became more labour intensive. Farmers shortened fallow periods and cultivated less productive lands. Much of the area became deforested. The first notable fortifications date from 150 to 300 AD. The Late Preclassic Maya faced population pressure, a strained resource base, and an increasingly competitive environment. They sought at least two solutions: agricultural intensification and increased sociopolitical complexity.

    Formal, public architecture and social differentiation became more evident by the Middle Preclassic and increasingly afterwards. In the Late Preclassic, there was a two or three-level administrative hierarchy. Population, agricultural investment, sociopolitical complexity, architectural elaboration, and conflict continued to increase. Between 534 and 593 AD, there was a decline in the construction of monuments. There was political decentralisation as stelae (stone monuments) appeared for the first time in the periphery. There is, however, no evidence of lower sociopolitical complexity across the region. The Late Classic saw resurgence and culmination of the trends begun in the Preclassic. Between 652 and 751 AD, there was a high degree of homogeneity in the style and iconography of monuments.

    Late Classic population levels, despite agricultural intensification, approached their upper limit as population growth levelled off. Population peaked between 600 and 830 AD, depending on the region. The city of Tikal reached a maximum population of 50,000 in the Late Classic. The population density was about 200 persons per square kilometre, making it one of the most densely populated areas in the pre-industrial world.

    Intensive agricultural methods were permanent and organised and included: canalisation and raining of river margins and swamps to create raised and channelled fields, water channelling and storage, terracing of hill slopes to direct drainage, trap silt, and create fertile areas, and a variety of miscellaneous features like checked dams and walled fields. Agricultural practices in the Classic period involved a suite of techniques fitted to different circumstances with differing levels of intensification and productivity. Population densities and forest clearing may have prompted the Maya to maintain lots for firewood production.

    Mayan society was complex and highly stratified. The social order consisted of a ruling class, a mid-level hierarchy of artisans and bureaucrats, and the peasants. Leadership was hereditary with descend groups. Rulers tried to fortify their position with sculptural art, most notably in stressful times. The distribution of population and settlements reflects the political climate. The organisation of colonies mirrored the organisation of society. At the apex of each polity was a primary centre like Tikal. Each major centre dominated some minor centres with less sculptural art and monumental architecture. Each subordinate centre administered a local peasantry. As political fortunes changed, centres rose and fell. Complexity, and its costly manifestations, increased over time, reaching a peak in the Late Classic. The most prominent building period in Tikal was between 692 and 751 AD. The buildings became increasingly secular, suggesting that administrators and nobles had become more powerful.

    Warfare and militarism intensified during the Late Classic. The art of this period shows a stronger emphasis on captives and conquest. Population growth may have stimulated competition and conflict. Alternatively, militarism may have induced population growth. War promoted the concentration of population in centres, which offered safety from attack. The limits of prehistoric warfare made prolonged sieges impossible. Security requirements and management of conflicts promoted hierarchical organisation and economic stratification.

    A burst of monumental construction preceded the collapse. There was evidence of political decentralisation during the breakdown. As construction ceased at the primary centres, many small sites erected monuments. There is some evidence of foreign invasions. With the collapse, the following elements of complexity disappeared: administrative and residential structures, the erection and refurbishment of temples, stela construction, manufacture of luxury items, and Classic calendrical and writing systems. There was also a population decline, estimated to be from 3,000,000 to 450,000 over 75 years. The collapse affected each site according to the peculiarities of its circumstances. Distressed cities raided and caused devastation among their neighbours.

    The Maya were a high-density stressed population practising intensive agriculture, living predominantly in political centres, supporting the elites and public works programmes, and competing for scarce resources. There was good reason for military competition. There was population and resource stress. The topographic redundancy of the surrounding areas allows us to understand how this situation developed. As a population impinges on the capacity of its food production system, fluctuations in productivity become increasingly consequential. In environments with topographic diversity where food production systems with different productivity cycles exist nearby, people usually alleviate resource fluctuations by developing regional economic symbiosis. Local groups can insure themselves against lean times by converting temporary surpluses into reciprocal obligations that they call in in times of scarcity. Available methods are trading, reciprocal feasting, or contributing to a hierarchically administrated regional resource pool.

    This strategy is called spatial energy averaging. It can lead to regional sociopolitical aggregates based on economic cooperation directed by self-interest. It requires diverse production systems that fluctuate asynchronously and are in close proximity so that transport is economical. When production cycles are synchronous, this causes competition, raiding, and warfare. Productivity fluctuations were of concern to a Mayan population as population density became high. The intensive systems of the Preclassic and Classic populations would have been susceptible to the climate, plant diseases, pests, and nutrient loss. The Mayans lived in a situation of significant topographical redundancy. Neighbouring populations experienced nearly the same productivity cycles.

    When population density increased, the short-term solution for each local group was warfare and raiding its neighbours as the alternative was famine. Longer-term solutions were agricultural intensification and the establishment of a hierarchically managed economy. There were no permanent solutions. With each establishment of a higher capacity production system, population numbers increased further. It is no accident that population pressure, warfare, and sociopolitical complexity emerged in unison in the Middle and Late Preclassic. The organisation for war required leadership and promoted a social hierarchy. Fortifications did exist, but most conflicts would have involved raids on fields and storage facilities. That, in turn, increased subsistence stress as populations aggregated into smaller areas that were better defensible, which promoted a further intensification of agriculture.

    The Maya of the Classic period were engaged in a system of competitive relations in which advantage would accrue to larger centres that invested more in competitive display and could mobilise larger populations. Warfare became an element of politics and regional dominance hierarchies. The high population density occurred with vast hydraulic and agricultural engineering, sociopolitical complexity, massive public works, and military competition. Complexity and architectural investment grew significantly before the collapse. Population growth, however, began to level off. The cost of the complexity fell on the support population. There appeared to have been a growing crisis in the food supply that climaxed in the Late Classic. There is evidence of malnutrition and diseases. Females were better fed than males suggesting a policy of encouraging population growth.

    In the Preclassic and Classic periods, Mayan society showed increased investment in complexity and declining marginal returns for that investment. At the end of the eighth century AD, the Mayan population was so weakened that society was ripe for a stress surge. By the time of the collapse, military conquest would not even have provided a temporary respite as it would have meant larger impoverished populations to support. In the short term, the breakdown improved the standard of living for peasants. They were relieved of the burden of supporting a hierarchy. In the long run, the agricultural population itself decimated. It was a political and demographic disaster. The Northern Maya Lowlands were not affected by the southern collapse and grew stronger.

    The Chacoan collapse

    Chacoan society in the San Juan Basin of New Mexico left only archaeological remains. The area is arid and not very suitable for agriculture. In the middle lies Chaco Canyon. Temporal and spatial variations were critical in such a moisture-deficient area. A regional system of social complexity, political stratification, and economic symbiosis developed. The Chacoan architecture consisted of Great Houses with storage rooms. The populations probably were low compared to the size of the structures. A road network spread outward from Chaco Canyon to the outliers. These roads are wide and straight. Evidence for labour mobilisation and energy expenditure on the great houses and social and economic differentiation in mortuary practices suggests that Chacoan society was stratified.

    By the tenth century AD, population growth in the San Juan Basin had reached the point where local groups no longer had the option to move into alternative territories when faced with subsistence stress, leading to the cultivation of increasingly marginal lands. Where population density is high and where population units are territorially constrained, it becomes necessary to ensure access to the agricultural produce of larger territories to guard against the effects of droughts, frosts, and raids. That is especially so when environmental conditions for agriculture are marginal. There is an inverse relationship between the agricultural productivity of high and low altitudes. In warm and dry years, the conditions on higher elevations are better. In cooler and wetter years, the pattern reversed. It encouraged exchange relationships.

    Populations in the Basin gain insurance against productivity fluctuations by access to territories as diverse as possible. If each local group had to allocate resources toward the tasks of identifying potential trading partners and their production levels and establishing reciprocal economic relations with each other, the duplication of administrative costs of hundreds of local groups would have been enormous. A single administration for all groups would reduce these costs. Additional benefits of hierarchical management of regional economic symbiosis were:
  • providing for the distribution of resources, thereby reducing competition and conflict
  • providing for authority to requisite surpluses when economic exchanges were imbalanced or delayed balance
  • centralised pooling to serve a diverse territory
  • support of specialists who monitor surpluses and deficits in the region

  • Chaco Canyon was the most efficient location for administering an energy averaging system because it was at the centre of the San Juan Basin. A three-level hierarchy appears to have operated in the area. Elites in the outliers mediated the participation of local villagers and interacted directly with the regional elites in the Canyon Great Houses. Resources exchanged up to and down the hierarchy would have included crops, firewood, building materials, animal products, and pottery. It appears that the population of the basin obtained a valuable return on its investment in complexity by lowering administrative costs and increasing the effectiveness of an energy averaging system. Beyond its establishment, further expansion of this system may not have been so advantageous. Around 1100 AD, it was at its height but on the eve of collapse. Late trends include:
  • increasing numbers of outliers, each requiring the construction of a Great House
  • a spurt in building activity in the Chacoan towns in the canyon itself, which doubled labour requirements
  • a decreasing mean distance between outliers
  • a growing number of outliers in the low productivity, low diversity basin

  • This combination of trends increased the overall cost of the system while reducing its effectiveness. With declining distances between outliers, a growing number of Chacoan towns with similar productivity cycles emerged. After enough outliers were in place to maximally exploit environmental diversity, new ones reduced the overall effectiveness. Incorporating communities from the basin interior made it even worse as this area had little to offer. Diversity was the best characteristic of this marginal low-productivity environment. The Chacoans initially made wise use of it. The system that provided subsistence security for a regional population began to experience a declining marginal return on complexity. The deterioration coincided with a significant increase in investment in architectural construction. Some outlier communities began to withdraw from the network, setting in motion the collapse. A final blow may have come from a severe prolonged drought from 1134 to 1181 AD. The Chacoans had survived previous droughts without collapsing.


    The three cases were significantly different in sociopolitical structure, level of complexity, economy, territorial extent, evolutionary trend, and the details of their collapses. The collapse of these societies cannot be understood only by reference to their environments, subsistence practices, outside peoples, population growth, catastrophes or sociopolitical dysfunction. In the background, there was a declining marginal return to investments in complexity, making collapse increasingly likely. The three cases allow for several conclusions:
  • In each case, the costliness of complexity increased over time while benefits to the population declined.
  • In each case, substantially increased costs increased late before the collapse and were imposed on a population already weakened by the declining marginal returns.
  • For Rome and the Maya, the population levelled off or declined before the collapse, and the well-being of most people deteriorated. For the Chacoans, this is not clear.
  • For the Maya and Chacoans, the subsequent abandonment of their territories and the lack of substantial reoccupation suggests environmental degradation.
  • In each case, peoples on the periphery (the Northern European barbarians, the Northern Maya, and the Western and Eastern Pueblos) rose to prominence after the older society had collapsed.

  • The usual explanations fall short of fully explaining these cases:
  • The fall of Rome was not due to the barbarians alone as the empire was economically, organisationally, and military stronger than its besiegers.
  • The fall of the Maya was not due to a peasant revolt, invasion, or a decline in agricultural output, as the Maya were able to increase agricultural productivity.
  • The Chacoan collapse was not due to drought or environmental deterioration as the Chacoans could deal with them.

  • Summary and implications

    Collapse is a sudden, pronounced loss of an established level of sociopolitical complexity. A society that has collapsed is suddenly smaller, simpler, less stratified, and less socially differentiated. Specialisation decreases, and there is less centralised control. The flow of information drops, people trade and interact less often, and there is less coordination among individuals and groups. Economic activity goes down while the arts and literature see a decline. Population levels drop. For those who are left, the world shrinks.

    Complex societies are not a discrete stage of cultural evolution, but each society is at a point in a continuum. Complex human organisations emerged relatively late and are a historical oddity. Where present, complexity needs constant reinforcement. Leaders, parties, and governments need to establish and maintain legitimacy. That requires some responsiveness to the support population. Investments in legitimacy and coercion represent a cost that any complex society must bear.

    The conflict school sees the emergence of a state coming from the need to protect the interests of the propertied classes. Integration theory suggests that governments and other elements of complexity emerged to serve the needs of society. Integration theory better accounts for the distribution of the necessities of life and conflict theory for the surpluses.

    The following concepts help to understand collapse:
  • Human societies are problem-solving organisations.
  • Sociopolitical systems require energy for their maintenance.
  • Increased complexity has an increased cost per capita.
  • Investment in sociopolitical complexity as a problem-solving response often reaches a point of declining marginal returns.

  • Sociopolitical organisations constantly encounter problems that require increased investment merely to preserve the status quo. The investment comes in forms like the increasing size of bureaucracies, growing specialisation, cumulative organisational solutions, increasing costs of legitimising activities, internal control and external defence. The initial investment in complexity may be a rational solution to perceived needs, further needs require more costly responses, and continued investment in complexity will have declining marginal returns.

    A society that has reached this point cannot simply try to maintain the status quo. Complexity is a problem-solving strategy. As new problems arrive, societies invent new solutions, typically with additional costs. The marginal returns on these investments diminish at an increasing pace. Collapse becomes increasingly likely. Two factors can make such a society collapse. A society might invest ever more heavily in a strategy that yields less and less. Productive capacity and accumulated surpluses may meet current needs. When major adversities (stress surges) arise, there is little or no reserve to counter them. Second, declining marginal returns make complexity a less attractive strategy so that parts of society may find separation or disintegration increasingly advantageous.

    The public, as well as academics, share the idea that collapse is catastrophic. People believe that civilisational complexity is desirable and the ultimate accomplishment of human society. Complex societies are a recent development. A breakdown can bring us back to the prevailing human condition of low complexity rather than chaos. If collapse is due to declining marginal returns on investment in complexity, it is an economising activity. A population that receives little return on the cost of supporting complexity, the loss of complexity brings economic and perhaps administrative gains. Under those conditions, collapse may not be a failure to adapt but rather the appropriate adaptive response. Collapse may only be a catastrophe to specialised people and those who cannot adapt. That can still be a large portion of the population. For instance, a significant population reduction followed the Mayan collapse.

    Must every complex society collapse? Does investment in complexity always come to the point where the marginal return declines? Modern economic research does not give a clear answer to that question. Societies with the necessary capital, technology, and financial or demographic incentives, obtaining a new energy subsidy through empire building or exploiting a new energy source, can for a time reverse a declining marginal curve or provide the wealth to finance it.

    Peasant revolts can be explained better by marginal returns on investment in complexity rather than taxation as such, even though ideology can make peasants aware of their marginal status. Polybius suggested that the triumph of Rome over Carthage was since Rome was increasing in power while Carthage was declining when they came into conflict. The Law of Evolutionary Potential suggests that older, established states become fossilised and unable to adopt innovations. Newer peripheral peoples outcompete them. It relates to the declining marginal return on investment in complexity.

    Another question is why there was no collapse in Europe after the fall of the Western Roman Empire. There are significant differences between the evolutionary histories of isolated dominant states and clusters of competing peer polities. Mutual interaction, which can be exchange and conflict, usually conditions their evolution. Examples are the small city-states of Aegean and the Cyclades or the centres of the Mayan Lowlands that interact on an approximately equal level. In such situations, the option to collapse to a lower level of complexity invites another polity to take over. And so, investment in organisational complexity must be maintained at a level comparable to one’s competitors, even if the marginal returns are unfavourable. Such a situation seems to have characterised the Maya, whose individual states developed as peer polities for centuries, and then all collapsed within a few decades.

    The states in Europe have been in a similar situation since the demise of the Carolingian Empire. During the last 1,500 years, Europe has seen interaction and competition between peer polities. Collapse is not possible unless all members collapse at once. The demise of one polity would lead to the expansion of another without loss of complexity. In the Cyclades, the existence of other states legitimises their state in the eyes of its citizens by Peasant political action would therefore aim at reform rather than decomposition as the failure of the polity would mean domination by another similar regime. The European peasants opted for increasing participation in the decision making process to secure a more favourable return organisational investment. Class conflicts thus led to political evolution only when the less costly option, collapse, was not available. It may not be a coincidence that participatory government emerged in situations of peer polity competition like in ancient Greece and modern Europe.

    The warring states period of China is a notable exception. Here peer polity competition led to the development of an ideology of good government and the protection of the populace. Good rulers received the Mandate of Heaven and continued to enjoy the Mandate as long as they governed well. Cessation of good government, or a series of catastrophes, were signs that a dynasty had lost the Mandate of Heaven. Perhaps a participatory government was not possible in larger ancient societies.

    The Byzantine and Ottoman empires slowly disintegrated but did not collapse. Both gradually lost power and territory to competitors. Collapse can only occur in a power vacuum when no competitor can fill the political vacuum caused by disintegration. It may also be why the Mayan and Mycenaean centres collapsed simultaneously. The Mayan and Mycenaean petty states locked into competitive spirals, so they all had to increase their investment in military strength and organisational complexity. No polity could withdraw as this would have led to the absorption by a neighbour. Collapse must be simultaneous as they reach the point of economic exhaustion together, and no outside powers were in a position to take advantage of the exhaustion. By contrast, the Greek city-states had powerful neighbours who could take advantage of a political vacuum so that they lacked the option of collapse. And so, declining marginal returns need not always lead to a breakdown, but only when there is a power vacuum.

    Declining marginal returns can clarify the collapse process in very different cases. Each society that has collapsed did so under a unique set of circumstances. It can help to explain:
  • why resource depletion leads to a collapse in some cases and economic intensification in others
  • why catastrophes cause a collapse in some cases and not in others
  • why complex social systems designed to handle catastrophes succumb
  • why complex societies do not respond sufficiently to new circumstances is based on a failure to adapt assumption which may not be correct as complexity reduction can be the appropriate response
  • that other complex societies impede collapse as peer competition promotes investment in complexity regardless of the cost
  • that conflict, contradiction and mismanagement require an explanation why elites behave irrationally as peasant political action is less likely to occur under a high but static tax load

  • A simple lesson of systems analysis with powerful applications may be that we can never do merely one thing. Good intentions are largely irrelevant in determining the result of altering a complex system. With the feedback relationships inherent to such a system, one can rarely fully anticipate the full consequences of any alteration. The same applies to misbehaviour. Elite mismanagement can only be partially responsible for the evolution of any complex society. Leadership is less crucial than many people imagine. Circumstance based perception may be of greater importance. When the marginal return on complexity rises, the payoff of society-wide investments overshadows almost everything a leader does. Conversely, when marginal returns are declining, anything a leader does is bound to make the leader appear incompetent.

    Complex societies are vulnerable to collapse. Although it may be an economic adjustment, it can nevertheless be devastating when much of the population does not have the opportunity or the ability to produce primary food resources. Many contemporary industrial societies fall into this category. The breakdown of these societies would entail vast disruptions, massive loss of life, and a significantly lower standard of living for the survivors. Other scenarios for contemporary collapse include
  • large-scale war, for instance, nuclear war
  • environmental degradation, for example, pollution
  • depletion of critical industrial resources
  • general economic breakdown due to debts

  • As in the study of historical collapses, those concerned about current conditions have ignored the principle of marginal returns on investment in complexity. Some of the data are certainly disturbing as patterns of declining marginal returns can be observed in at least some contemporary industrial societies in the following areas:
  • agriculture
  • minerals and energy production
  • research and development
  • healthcare
  • education
  • government, military, and industrial management
  • productivity of GNP for producing new growth
  • some elements of improved technical design

  • At least some industrial societies are now experiencing declining marginal returns in several crucial and costly investment spheres. On the one hand, some economists argue that we do not face real resource shortages but only solvable economic dilemmas. They assume that with enough financial motivation, human ingenuity overcomes all obstacles. The opposing view of many environmentalists is that current well-being is at the expense of future generations. Stimulating economic growth will lead to faster depletion, hasten the inevitable crash, and make it worse when it comes. Both approaches have the same flaw: not taking into account historical factors.

    The optimists base their beliefs on the principle of infinite substitutability. They think that by allocating resources to R&D, scientists can find alternatives for resources in short supply. This principle does not simply apply to investments in organisational complexity. Economies of scale and advances in information processing lower costs, but these too are subject to diminishing returns. The marginal costs of R&D have grown so high that it is questionable whether technological innovation will contribute as much to the solution of future problems as it has done in the past.

    Consider what might be needed to solve the problems of food and pollution. To increase world food production by 34% between 1951 and 1966, required increases in expenditures on tractors of 63%, fertilisers of 146%, and pesticides of 300%. Pollution control shows a similar pattern. For instance, removing all organic waste from a sugar processing plant costs 100 times more than removing 30%. Reducing sulphur dioxide in the air of a US city by 9.6 times or of particulates by 3.1 times raises the cost of control by 520 times. Allocating more resources to R&D to sustain economic growth can only give a temporary respite from diminishing returns.

    In past societies, declining marginal returns led to weakness, disintegration and collapse. So, if we control pollution and population, and manage to circumvent resource depletion, will our fate be sealed by the high cost and low marginal returns that these things require so that not solving these problems is the economical option? There are critical differences between the current and the ancient worlds with significant implications for collapse. Today, the world is full of complex societies. That is unique in human history. In the past, collapse could only occur in a power vacuum. Collapse is neither an option nor an imminent threat because of peer polity competition. Any nation vulnerable to collapse can opt for absorption by a neighbour, economic support by a dominant power or payment by the support population of the cost of complexity despite detrimental returns.

    Proposals for ending economic growth will not work as there is a close link between economic and military power. Unilateral economic deceleration equals unilateral disarmament. Peer polity competition drives increased complexity and resource consumption regardless of human and ecological costs.

    It does not mean that dominant powers will collapse if there had been no peer polity competition. Both primary and secondary world powers have sufficient economic strength to finance diminishing returns well into the future. As seen in the cases of the Romans and the Maya, peoples with incentives and reserves can endure declining marginal returns for centuries before their societies collapse. Peer polities usually undergo long periods with upwardly-spiralling competitive costs and downward marginal returns. It can end in the domination of one state or by a breakdown in unison. So if a collapse comes, it will be global.

    In ancient societies, the solution to declining marginal returns was capturing a new energy subsidy. In economies based on agriculture and human labour, territorial expansion accomplished this. The foundation of today's economy is stored energy reserves, and the world is full of humans, so this course is not feasible. Technological innovation and increasing productivity can forestall declining marginal returns for a while, but a new energy subsidy will at some point be essential. Even if the point of diminishing returns to our present form of industrialisation has not yet arrived, it will inevitably do so. We have at least reached declining returns on our reliance on fossil fuels. The development of new energy sources is essential for the continuation of human civilisation.

    There are reasons for optimism as well as pessimism. We are in a curious situation where competitive interactions force a level of investment, and a declining marginal return, that might ultimately lead to collapse except that competition prevents it from happening. That could mean that living standards in many people will not rise or even decline as the rising cost of complexity is paid for by the support populations. The political conflicts this causes can create a dangerous situation in the world.


    The Collapse of Complex Societies, Joseph Tainter, Cambridge University Press, 1988.