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The archeological evidence of ancient human settlements that we have today provides only a whisper about the rich lives lived by the tens of millions of inhabitants of human settlements throughout the ancient world. Estimates of the number of people who were alive about 10,000 years ago converge around the number 5 million (Thomlinson 1975; McEvedy and Jones 1978). If the average size of a hunter-gatherer kin group was about 24 individuals of various ages, then there were, roughly speaking, about 200,000 kin bands at the dawn of the first settlements. The process of convergent evolutionary change that led a very small percentage of those kin bands to begin settled life as agricultural villagers took thousands of years to take hold. And it likely took many generations in each place to become the dominant form of mentality. But the result led to at least tens of thousands of instances where settlements were first established by a small kin band. Yet we know almost nothing in detail about any of these small, original hamlets . The physical evidence of their existence is either lost forever, beyond the reach of our current methods to discern, or just simply not yet discovered. We have shreds of evidence about only a few.

And yet the GST model can be used by contemporary researchers to give some powerful insights into what these vanished ancient places must have been like. Once the idea of life in a permanent settlement took hold in the imagination of the first few generations of agricultural villagers, the dynamics of human problem-solving shifted its focus from the context of a small nomadic band to that of a small settlement. As described in Chapter 2, a GST model of problem-solving can be used to create a generalized model of a human settlement as a complex system comprised of three principal sub-systems. Here, we reproduce the same diagram from Chapter 2 and rename it Fig. 5.1, for the reader’s convenience.

Fig. 5.1
figure 1

Human settlement with sub-systems

Full size image

The first sub-system is a set of relationships that allows the settlement to meet the biological needs of its living inhabitants. Settled villagers need food, water, warmth, clean air, and sanitary living conditions. The second sub-system is a set of material processes that provide the settlement with its built environment. Structures needed to be built from locally accessible materials. Structures needed to be durable enough to provide shelter to inhabitants against the uncertainty of local climates and variable weather conditions. Even the most rudimentary settlement needs some type of infrastructure to provide access to water, food, light, heating and/or cooling sources. Infrastructure needs to facilitate movement of people and goods within the settlement and people need to have ways of removing harmful waste. Locally accessible materials were also needed to build public monuments, as well as walls and other forms of settlement defense. The third sub-system is a set of social relationships that could facilitate group cohesion, trust, order, and collective problem-solving capacities among the residents of the settlement. The creation and development of these social relationships may well have been among the original drivers for urban living. The monumental religious structures, for example, at Göbekli Tepe and Çatalhöyük in the Fertile Crescent suggest that such relationships predated and may have been central to the founding of larger settlements.

Even without knowing the specifics, we can appreciate that each settlement, no matter how small, must have had its own unique set of interconnected complexities that bound together its own sub-systems. The residents of each vanished settlement must have created their own ever-changing balance among the dynamics of each sub-system: living process, material process, and social process. Each settlement that persisted for any amount of time must have had some level of problem-solving resilience in order to survive within the unique physical and climatological constraints of its own local natural environment. Settlements emerged and persisted in almost every climate zone and at every altitude. The force of human agency proved just as creative at solving the problems of life in ancient settlements as it had been in solving the problems of life among the countless number of small nomadic bands of people who had comprised all of humanity since Homo sapiens first evolved.

New Patterns of Social Relations

The problems of social relations within human settlements were especially more complex than the social relations experienced by small nomadic kin bands. When social relations became problematic in a small band of nomads, the group could either disband entirely or it could divide itself in smaller units. Small groups could always break off from the larger one to seek their own destiny. But permanent settlements created a much greater need for solving problems of social relations since the act of breaking apart had many more consequences. New forms of authority were needed to avoid conflicts and to resolve them when they arose. We have no direct evidence about the nuances of social relations in ancient hamlets since we have only a few archeological remains. Yet our understanding of more recent human behavior can be used to develop reasonable estimates (Johnson and Earle 2000; Bettinger et al. 2015).

We assert that it is reasonable to conclude that the transition from nomadic bands to settled agricultural villages expanded three universal forms of collective social authority that had already been well-established in hunter-gatherer cultures : heredity, violence , and religion . The first form of ancient social authority that people likely experienced in hunter-gatherer cultures was hereditary authority. Social authority based on heredity had existed for untold millennia within small nomadic bands. The establishment of permanent settlements expanded and elaborated this cultural legacy in new institutional ways through the rise of “big men,” chiefdoms, kingships, and other forms of hereditary nobility and social hierarchy (Johnson and Earle 2000). The larger the settlement, the more sophisticated these forms could become.

A second traditional source of social authority was intra-group violence, or at least the threat of violence. There was, of course, nothing new about violence in the human experience. There is abundant evidence of violent interactions among various nomadic bands of people prior to the creation of settlements (Keeley 1996). But the most severe violence had been between different groups, not within groups. Once people from different groups became bound together by settling down in the same place, new forms of direct violence and/or indirect coercion were needed to steer peoples’ behaviors into acceptable patterns and to punish those whose behaviors transgressed established norms.

The third, and perhaps most powerful, source of traditional social authority that was expanded by settling down is best described in English by using the word “religion ,” although we caution readers that the general term “spirituality” may better capture the concept. Ever since modern humans evolved the cognitive capacity to be self-aware of their own individual existence, people have contemplated their origins and their place in the world, in contrast to the place of other individuals, other animals, plants, and the full range of inanimate objects they encountered in their daily lives. Beginning at about the time ancient Cro-Magnon people began to extend their range outside of Africa, they began leaving evidence of higher-order contemplative cognitive behaviors in the forms of abstract figurines, magnificent cave art, etc. For tens of thousands of years since then, nomadic hunter-gatherers were free to develop their own conception of themselves within the context of their own cultures. They were free to derive their own codes of behavior that they thought were appropriate.

Once permanent settlements were established, the codes of acceptable behavior and beliefs that came from the cultural legacies of many different small bands were blended and fused into new forms. Ideas from which those many different codes were deduced, expanded, and elaborated into more complex frameworks can be described as religious and/or spiritual beliefs. Those patterns, in turn, generated more complex codes of socially acceptable and socially unacceptable behaviors. These elaborate processes of cultural evolution were only possible because settled life brought together people from different cultural legacies who had to interact with each other every day to solve the many new problems of settled life that their new lifeway created.

Religious, or spiritual, authority was an especially powerful type of social influence because the boundaries of acceptable behaviors that were rooted in religious beliefs often did not need to be enforced with violence because religious beliefs could be instilled in each individual’s inner mind in the form of a moral code (Wade 2009). Moral codes could include virtually any type of behavior, including behaviors that our modern minds might never accept as moral. Yet such codes had legitimate authority to guide and mediate individual and collective behaviors within the cultural boundaries of the settlements where they evolved. As a rule, each individual’s inner mind has its own concept of right and wrong and its own conception of how the individual relates to the external world. Religion helped to solve the deeply felt human problem of centering themselves and their groups within their own experience of life and finding meaning for it all. Consequently, when a religious code was accepted by that individual, the individual became the principal source of his/her own discipline in regard to interactions with other people.

From one settled generation of agricultural villagers to the next, each of these ancient sources of social authority—heredity , violence , and religion —was transformed into more elaborate forms and combined in countless different ways to form many different behavioral patterns that we can describe with the general term culture. There is, perhaps, no more powerful source of collective social authority than the ability to program the inner minds of one’s neighbors through the development of accepted patterns of behavior that are reinforced by the combined social authority of violence , heredity, and religious beliefs.

The continual mixing of ancient forms of authority into new forms of settled culture also created new forms of social authority . Perhaps the most consequential new form of social authority was gender. Experts in hunter-gatherer culture originally argued that men hunted and women gathered, but that idea has been discredited (Jarvenpa and Brumbach 2014; Dyble et al. 2015; Alesina et al. 2011). Indeed, the evidence that is available today reveals that hunter-gatherer cultures were fundamentally egalitarian in most ways, including the division of labor and authority by gender. Persistent cultural patterns of gender differentiation seem to have originated as part of the cultural transformations that are associated with the rise of the settled lifeway.

The evolutionary paths that led ancient people to settle down created thousands of these new settled hamlet and village cultures. Yet not all cultures created sub-systems that could support sustainable settlements. Those settlements failed to persist. Other local cultures proved to be more successful, and those settlements survived. Persistence, however, did not always lead to growth. The GST model leads us to expect that most successful settlements found their own balance among their sub-systems and grew within the boundaries of their local environmental conditions. There is no reason to assume that settlement growth was a goal. For the great majority of ancient villagers, they were content simply to live their lives within the constraints of their immediate surroundings. They sustained themselves and their nearby associates, and they pursued the fullness of life through reflective leisure and interpersonal relationships. Yet a handful of settlements did grow beyond their initial constraints, driven by whatever set of circumstances and/or ambitions. Some small hamlets grew into villages . Some villages grew into towns. Some towns grew to a scale where they could be considered cities.

In a classic article about cities and culture written in the 1950s, the anthropologists Redfield and Singer (1954) classified ancient (and modern) cities in regard to the dynamics of their social relations. They concluded that the ancient settlements that grew into cities tended to be those that used their systems of social relations to create, refine, and reform one dominant established local culture. They identified these settlements as “administrative-cultural” places of “orthogenetic transformation.” Each ancient city in this category, they argued, put great energy into creating its own form of orthodoxy in regard to a dominant religious/cultural “moral code” of expected behaviors and beliefs. Everything about the experience of day-to-day life in these places focused the attention of inhabitants on core aspects of local culture and locally acceptable patterns of individual and group behavior and beliefs. Uniformity of cultural expression was valued. For example, cultural knowledge was transformed into ritualized practices that were thought to sustain life, even if doing so meant the existence of death cults and/or human sacrifices. Specific foods were favored or shunned based on religious beliefs. Daily practices of cleaning, child nurturing, sex, and other behaviors were all approved or rejected based on ideas related to religious acceptability. New knowledge about building practices, technologies, and/or building materials was also filtered through cultural and religious screens before specifically acceptable behaviors could emerge. Distinctive building alignments, forms, and designs transmitted cultural beliefs about gods, the heavens, and each culture’s orthodox ideas about the proper hierarchy among its residents. The dynamics of social relations among groups were guided by elaborate rituals, symbols, and other forms of coded acceptability.

Redfield and Singer used the term “literati” to describe the elites in orthogenetic places. The elite social authority of local literati rested on their refined understanding of the precepts of acceptable local cultural forms of expression, behaviors, and beliefs. All cities cope with change, of course. Yet Redfield and Singer argued that the literati elites in orthogenetic cities maintained social order in their cities by serving as the conservators of past ideas, despite the fact that they continually needed to cope with at least some magnitude of change if the city was to survive over time. The most successful orthogenetic cities, Redfield and Singer concluded, were those “where religious, philosophical and literary specialists reflect, synthesize and create out of the traditional material new arrangements and developments that are felt by the people to be outgrowths of the old. What is changed is a further statement of what was there before” (1954: 58).

Largely because of their relatively strong cultural clarity, anthropologists have argued that successful orthogenetic settlements tended to expand into larger cities. Their ability to grow eventually exerted strong influences on the cultural trajectory of nearby settlements. At some point when the culture of one settlement would begin to influence—and dominate—the cultural development of multiple nearby settlements, historians begin to use the term “civilization” to describe the complex connections that emerged among multiple settlements. Different settlements, and the hinterlands that lay between and nearby them, are said to comprise parts of a unified civilization. Their inhabitants begin using the same solutions for the problems of life, the same style and materials for structures, tools, and pottery, the same symbols and myths, and the same range of codified rituals and other morally codified acceptable and unacceptable behaviors. In this way, the term civilization is used to identify an integrated network of specific settlements and interconnected spaces. Although the definition is not precise, it usually implies that the network contains multiple, relatively large settlements that have created some set of transportation connections, by land or by water, through which ideas, people, and sometimes goods can be traded.

Redfield and Singer argued that unified cultural clarity and a strong sense of moral order often gave orthogenetic settlements the capacity to expand into broader civilizations. Archeologists find scattered artifacts that provide evidence of these so-called lost civilizations by identifying common building styles, pottery styles, and burial practices. Specific symbols and figurines of people, animals (real and mythical), and abstract shapes often provide evidence of cultural influence among settlements stretched out over great distances. An excellent example is found in the archeological evidence of the ancient Olmec civilization in Mesoamerica (Carmack et al. 2007). Artifacts dated over several thousand years, and across many different settlements in the region, show the gradual evolution of similar, small figurines into large stones. The earliest ceramic and wooden figurines depicted women standing without clothes and seated men wearing masks. These evolved slowly into less gender-specific versions, made of wood, ceramic, and stone. Eventually, the Olmec culture evolved into producing very large distinctive heads made by carving naturalistic male faces in very large basalt boulders. At least seventeen of these heads have been found, scattered through the Olmec region at various sites. Each is thought to depict one of the hereditary leaders of the Olmec civilization. Although different scholars offer different theories about the meaning of these artifacts, their existence and the uniform manner in which they changed over time in multiple places provides clear evidence of the regional scale and persistence of the unified Olmec civilization.

But not all successful ancient cities were orthogenetic. Redfield and Singer contrast these cities with heterogenetic cities. These settlements were less common among ancient places. Instead of placing primary value on continuity, these were places that gave value to incubating new ideas, new ways of thinking, and new cultural fusions. In heterogenetic cities, “the prevailing relationships of people and the prevailing common understandings have to do with the technical not the moral order, with administrative regulation, business and technical convenience” (1954: 57). Elites in these cities were “intelligentsia” rather than “literati.” New problems could be addressed with new ideas, even if those ideas conflicted with traditional customs. Heterogenetic cities usually tolerated at least some degree of cultural diversity, heresy, and dissent. Orthodoxy could be overcome when pragmatism provided unorthodox solutions to new situations. Heterogenetic cities created new and sometimes original fusions of older traditions that could create new forms of thought and new definitions of acceptable or unacceptable behaviors and beliefs.

Heterogenetic cities were less stable than orthogenetic cities, however, since they could more easily disintegrate into partisan power struggles. The act of loosening the power of orthodox thinking and tolerating multiple cultures in the same place also loosened the social authority of religious ideas. This could open new opportunities for those whose social authority rested largely on traditional heredity and/or violence . Secular nobles could grow stronger in heterogenetic places. But so too could simple tyrants whose only source of authority was brute violence. Yet these places also served as incubators for new types of social authority. This most commonly created an opening for knowledge itself to first emerge as an independent source of social authority. Every settlement was always in need of solving problems within and across its multiple sub-systems. Those who could learn how to solve those problems could thereby gain social status based on their wits alone. Pragmatic heterogenetic cultures gave new opportunities for elites to cultivate new mentalities that recognized accumulated secular knowledge as a legitimate source of social authority within their cultures.

Heterogenetic places often emerged in places that typically lay between civilizations that were more orthogenetic. Heterogenetic places were where orthogenetic cultures met and mixed along trade routes or at important intersections along land and water trade routes. The most successful of these settlements persisted when their elites consolidated control based on pragmatism, not dogmatism; knowledge, not violence. They were able to establish a more secular, albeit less comprehensive, set of moral codes and patterns of acceptable behaviors and beliefs.

The Minoan civilization that developed primarily on the island of Crete in the Aegean Sea from about 2600 bc to about 1400 bc is an excellent example of heterogenetic development. Crete is located at the crossroad of the Eastern Mediterranean between Egypt, the Near East, and Greece. Knossos , the major Minoan city included housing for a large number of people (perhaps 15,000), food storage space, religious spaces, administrative areas, and workshop and craft zones, none of which were protected by defensive walls. Unlike any of the palaces of ancient Egypt or the Near East, none of the ruins indicate that any part of the city served as the home or headquarters of a king or ruler. Indeed, Minoan culture played a vital role in transmitting components of many previous cultures to the Greeks. And yet the origins of Minoans seemed mysterious. Recent analysis of DNA, however, confirms that Minoans themselves were a broad mixture of people from the Greek mainland, northeastern Anatolia, and elsewhere in the Mediterranean world (Lazaridis et al. 2017).

Few ancient cities or larger civilizations provide pristine examples of either orthogenetic or heterogenic processes of change and transformation. Most were complex mixtures of these two factors. One factor or the other would dominate for a period of time, and the balance would evolve. The Olmec civilizations seem to have been primarily orthogenetic over many centuries. The Minoans tended to be more heterogenetic over time. Yet the Olmec and Minoan civilizations are only two of many (perhaps hundreds and thousands) of ancient “lost civilizations” in different sites spread throughout the world.

Archeologists have uncovered evidence for only a few. It is profoundly humbling to consider the number of instances in which a handful of small artifacts and the ruins of a few structures provide the only remaining physical evidence to indicate the existence of a distinctive culture/civilization in a particular place spanning a specific period of time. Sometimes the evidence suggests the dominance of an orthogenetic impulse and sometimes it reveals heterogenetic influences. But more often the paucity of the evidence that we have provides us virtually no insights into the rich, complex history and lived cultural experiences of the people whose lives played out within the boundaries of each culture. We know only that it existed. Yet each instance of a distinctive culture/civilization represents the lives of tens of thousands, hundreds of thousands, and sometimes millions of people whose experiences both shaped and were shaped by the complex social, biological, and technological systems that emerged in every permanent human settlement. Each system sustained people for hundreds and sometimes thousands of years before it dissipated and faded into obscurity. An unknowable number of cultures/civilizations left behind nothing more than a few scraps of artifacts as the only evidence that they ever existed. Sometimes we possess those artifacts. Yet most civilizations are likely lost forever. Mesoamerica, for example, yields artifacts of the ancient Olmec. But the largest center of Olmec culture, San Lorenzo , had only 13,000 inhabitants throughout that city’s extended region at its peak between 5500 and 5000 bc. Broader estimates of the total population of Central America and the Caribbean in those centuries range between hundreds of thousands and a few million people. The voices of all those other cultures are silent across the great spans of time.

The GST framework allows us to appreciate the scale of what has been lost. It also gives us a framework to trace some limited cultural influences over time as one civilization’s approach to solving problems in one sub-system reappear in the artifacts left behind by a later civilization. This limited style of “cultural genealogy” is never precise, but it is often the only physical evidence of cultural persistence from one era of civilization to the next before the invention of writing , which is quite recent. Digging through multiple layers of ruins in places that have been inhabited for thousands of years helps identify cultural continuities and discontinuities among the scattered remains of different eras. This work allows scholars to construct tentative trajectories of how previous cultures have (or have not) influenced the variety of human cultures that exist today.

For example, this approach allows us to appreciate the powerful orthogenetic influences that have stressed continuity and unity through thousands of years of political, cultural, and economic transformations that produced a broadly unified Chinese culture. We can identify how Chinese writing and cultural norms evolved from Xia to Shang , and then to the Zhou dynasty (Hsu 2012). The gradual emergence of common written Chinese characters created the ability for people to communicate with each other, over time and territory, even when their spoken languages were very different. We can appreciate how widely accepted social norms about the ruling legitimacy of social elites came to be associated with a perceived mandate from heaven. Furthermore, we can understand that the idea of a mandate from heaven did not depend on anyone narrow theological definition of what god or group of gods exerted authority in heaven. The concept was flexible enough to be shared among many different cultural groups. Each defined their own collection of ancestor gods, city gods, or nature gods. Yet the concept facilitated a type of cultural unity by creating the common belief that whomever ruled in any one time and place did so with legitimacy derived from above. This common culture was eventually unified further by Confucian teachings that connected heaven’s mandate to each individual’s own life experience. This interpretation of heaven’s mandate for each individual established a strong cultural impulse that associated each individual’s fate with the fate of the larger society. Every individual had a unique fate, but each individual’s fate was a necessary component of heaven’s mandate for all people. The meaning of life for each individual, therefore, was found partly in that individual’s role in their community’s collective life. This type of cultural development created a communal foundation for the definition of any viable moral code that could regulate or justify individual behavior.

In contrast, we can see modern Western culture as the product of more heterogenetic cultural developments beginning in the ancient Near East and migrating westward through the Mediterranean world. Written languages each developed their own phonetic alphabets rather than using common characters. This sharply restricted the creation of common knowledge across territory and time. And while ruling elites throughout the ancient Near East and Mediterranean certainly justified their social position by references to heaven, early Western civilizations had more distinct hierarchies of which gods were in charge, including a long-standing tradition that conceived heaven as a place ruled by only one god. Different theologies from ancient Egypt, the Hebrew prophets , ancient Persia and the Greeks, among others, also developed two strands of thought that were comparatively less central to Chinese intellectual traditions. The first emphasized separation between the fate of the individual and the fate of society. This focused more emphasis on each individual’s responsibility for their own moral fate. The second emphasized the transitory nature of each person’s biological life in favor of a future afterlife of some sort. The benefits that one should expect to realize from fidelity to any one particular moral code of conduct, therefore, may be otherworldly.

The scale of this book precludes an attempt to provide the reader with anything close to a full summary of the history of any of the civilizations that evolved over thousands of years after ancient people adopted the mentality of settled life, much less all of them. So instead we focus upon the application of generalized Darwinism and GST to selected ones. Moreover, despite the scale of what is lost, scholars have uncovered many examples through field research. And the few civilizations that developed writing have left us richer sources of evidence in the form of ancient texts. In place of a broader narrative of what is known, we offer the GST framework as a rudimentary device to help organize what little is known, and to guide our thinking in regard to the great majority of civilizations about which we know nothing.

The GST framework also allows us to appreciate what is perhaps the most humbling, and most awe-inspiring, analytical conclusion that emerges from the analysis of ancient human civilizations. Among all of the thousands of human cultures that were created and sustained by the establishment of permanent settlements, and among the hundreds of persistent civilizations that evolved among networks of permanent settlements, not one single civilization has ever dominated all of humanity at any one time. Until recent times, the greatest concentration of population in a handful of cultures seems to have occurred more than 2000 years ago when the total population of the Roman Empire reached its peak of about 50 million people. During that same era, Han China achieved a population that was perhaps as many as 60 million people. Each of these sprawling ancient civilizations was comprised of a vast network of cities, towns, and villages , all connected by systems of infrastructure that facilitated transportation, commerce, and communications. Each knew the other existed, but since their territories did not overlap, most of the influences they had on each other were filtered through layers of intermediaries. At their collective peak, these two ancient civilizations influenced perhaps 40–45% of the world’s existing population. But that scale of concentration did not last for long. Rome splintered between its eastern and western portions, giving rise to a wide range of new cultures. Han China was torn apart by local military commanders into multiple autonomous regions.

From one millennia to the next, not one civilization has ever been able to find durable solutions to the problems that come with complexity at the largest scale. Every human civilization that we know about originally emerged from preceding factors in its own unique environmental setting, found its own sustainable balance among the sub-systems that comprise any individual settlement (biological, material, social), evolved that balance in response to changing conditions long enough to establish itself as a growing, persistent, network of settlements, and then exhausted its ability to persist when confronted with the scale and complexity of problems that come with empire. Every civilization eventually has been overwhelmed by its own limitations. Some have collapsed suddenly. Most have dissolved less dramatically over time. Some have left only thin evidence that they ever existed.

Yet the failure of each individual human civilization, and sometimes the failure of each individual settlement that is associated with that civilization, is not a story of failure in regard to the evolving human mentality of settled life. Indeed, the constantly repeating cycle that creates new human settlements—and civilizations—often literally on top of the ruins of previous failed ones—attests to the success of the evolutionary path of settled life that H. sapiens began to follow only ten thousand years ago.

We characterize the history of any single settlement, and any broader civilization, as an ever-changing dynamic of problem-solving in order to maintain a sustainable balance among the complex needs of three principal settlement sub-systems: the system that creates structures and the built environment, the system that supports human life within that built habitat, and the system of social relations among people who settle there. Settlements sustain themselves over time when these systems are in balance. Settlements and civilizations break down, decay and dissipate when these systems are not synchronized. No settlement nor civilization to date has ever managed to solve every problem it encountered endlessly in all three sub-systems. Some have lasted only decades. Others survived over centuries. But all succumb eventually.

We assert that the most common causes of settlement break-downs are rooted in an accumulation of unsolved problems within social relations systems. Material systems and life-sustaining systems have many factors that can create complex problems to solve. But the complicating factor of human agency typically brings a higher level of complexity to problems within systems of human social relations. The collapse of individual settlements—and the broader collapse of civilizations—comes when unresolved problems of social relationships overwhelm the capacity of established authorities to create solutions. That is when things fall apart.

Some type of authority is always needed to resolve problems within a group of people. When a solution is identified it needs to be implemented and maintained without causing continual turmoil. Outside observers need not consider the solution fair or just. Rather, the solution only needs to be supported by enough different sources of social authority within that group of people that it moves from the category of “contested” to the status of “resolved.”

We described previously how three most ancient forms of authority (heredity, violence, and religion/spirituality) evolved during the hundreds of thousands of years when all modern people lived in small nomadic groups of hunter-gatherers. These forms of authority evolved over time into enhanced and more complex systems of authority when people adopted the mentality of settled life. Settled life created conditions that allowed new sources of social authority, such as gender, to emerge. In heterogenic settled cultures , local intelligentsia emerged and created the basis for a fourth source of authority: accumulated knowledge. Homogenetic cultures may have been more compelling than heterogenetic cultures in terms of their ability to inspire followers with persuasive unified worldviews and thereby grow quickly into larger civilizations. But the pragmatic nature of heterogenetic cultures imparted some advantages in regard to their durability . And all cultures were some mixture of these two forms. Consequently, the practical knowledge legacy of the heterogenetic components of most ancient cultures accumulated over thousands of years. Like all evolutionary processes, only a relatively few variants survived over time. Much was lost, but this legacy eventually created the foundations of writing , literature, engineering, science , accounting, mathematics, and perhaps most importantly, a new addition to the mentality of settled life that raised knowledge itself to a form of enduring social authority.

Much of the natural history of human settlements, starting 10,000 years ago and lasting until the advent of the industrial revolution , can be examined by using whatever bits of evidence and documentation we have available. They enable us to chart the paths followed by different groups of settled people as they blended the multiple sources of social authority in endlessly creative ways to address the evolutionary problems of built form, livable habitat, and social relations within the evolving human mentality of settled life. They provide evidence that over thousands of years the great majority of human settlements were established and maintained themselves within the constraints of their local environments.

Elements of the Cycle of Growth and Decline

Civilization brought great changes to human settlements. For instance, today we tend to think of growth as a natural goal. But this is a modern factor in our own mentality of settled, civilized life, not one that was a part of the mentality of hunter-gatherers or those who lived in the earliest settlements. The great majority of settled people throughout the past were content to live their lives within a context of as much local, homeostatic continuity as possible. They simply wanted to “go forth and multiply,” reproducing not only themselves biologically, but also the culturally learned lifeways of their immediate ancestors.

Yet, some ancient settlements did grow into broader civilizations. Beard (2015), for example, cuts through the many layers of myth about the early origins of Rome and gives us a masterful account of how one small, unremarkable settlement grew into the tight regional network of settlements today known as the Roman Civilization. That network eventually formed the basis of a great empire. There was no original desire for growth, let alone a desire for empire. The original Romans simply fell into a successful pattern of problem-solving that overcame constraints related to their own local climate, topography, and naturally occurring supplies of food and materials. Growth required the ability to produce more food to accommodate more people. Once the immediate local problems were overcome, growth continued by establishing reliable trade networks, through barter and through force when necessary, with other nearby settlements over land and/or water. A successful pattern emerged and took hold.

There is a large literature about the evolving local and regional patterns of city building, trade, warfare, and cultural influence that characterized the ebb and flow of the relatively few civilizations in the ancient world that developed a culture that pursued expansion. 1 That literature broadly recognizes that the ultimate problem that constrained the growth of expansion-oriented cultures in the ancient world was an unbreakable correlation between the expansion of any one civilization’s population and a decline in its ability to produce enough surplus of food and materials per capita to avoid an increase in deaths caused from limited food supplies and unsanitary built environments. Cyclical population increases and decreases may be described in terms of the elementary population growth equation in which the total size of a population in any given region at the end of any time period (usually a year) is equal to the size of the population in that region at the beginning of that time period, plus the total number of births, minus the total number of deaths, plus the total number of in-migrants minus the total number of out-migrants.

For example, if a region with 1000 people at the beginning of any given year had no in-migration or out-migration during that year, 40 people were born, and 10 died, the region’s population at the end of the year would be 1030. If in addition three people in-migrated and nobody out-migrated, the end of the year population would be 1033. If instead 5 people also out-migrated, the population would be 1028. Past this point, assuming that in-migration and out-migration are zero, this same equation can be rendered in terms of per capita birth and death rates so that ΔN/Δt =  bN −  dN where Δ signifies a change in a variable, N is the population size, t is a period of time, b is the per capital birth rate, and d is the per capita death rate. The value r =  b − d here is known as the “rate of natural increase” or the “per capita rate of increase” of the population. Essentially, r is the probability that any arbitrarily selected individual in the population will give birth during the time interval, discounted for his or her probability of dying. If r is positive (b exceeds d) then the population grows, and if r is negative (d exceeds b) then the population shrinks.

Accordingly, both birth rates and death rates in ancient cultures tended to remain high and virtually all regional economies remained stagnant. Birth rates were high because newborn children were highly valued as future sources of labor for raising crops in primarily agricultural populations. At the same time, death rates were high, largely due to insufficient nutrition (undernutrition), poor nutrition (malnutrition), as well as a high incidence of infectious disease (often from contaminated drinking water). In terms of economics, at root was a historically unbreakable inverse relationship between the size of a culture’s population and its ability to provide a per capita “real wage” to its people. The “real wage” was not cash, of course. Modern economists measure this concept in non-industrial cultures in terms of the amount of food and other essential items that the culture could produce on a per capita basis. Whenever starvation, disease, natural disaster, or war brought the size of a population down to a level that was lower than its long-run average level, the then-primarily agricultural labor would become relatively scarce. Landowners would therefore start to bid for scarce laborers, driving up real wages, allowing laborers to have access to more and better food and shelter, thus raising their standard of living. In turn, the rise in living standards would increase the number of children born that would survive into adulthood, thus tending to bring the size of the population back toward its average level, and at the same time tending to reduce the scarcity of labor (Khan 2008). The increase in population would continue until labor was no longer scarce, at which point landowners no longer had difficulty operating their farms. The landowners would then reduce the real wage back to its average level, leading once again to a decline in the living standards of workers. Then, the death rate would go back up. Thus, whenever living conditions temporarily improved, population growth would bring them back down. In terms of the elementary population growth equation, this meant that the rate of natural increase (r = b − d) remained low and that N, the size of the population, remained low. Thus, the human population had remained relatively small for tens of thousands of years.

The biological imperative to reproduce pushed against this barrier by urging higher rates of population increase. When populations encountered initial local constraints to the supply of food and materials in their early stages of growth, they solved them through creative local problem-solving as described by the GST model. This strategy is known as subsistence intensification (Johnson and Earle 2000). Subsistence intensification creates new knowledge in the form of new technology, in order to increase the productivity of the natural resources that exist in any specific setting. It is made necessary by the need to solve problems caused either by increasing populations, deteriorating environments, or both. Newly developed technology improves subsistence productivity and creates surpluses of food and other resources. This allows further population growth, which then puts increasing pressure on the available local resources, thereby giving impetus to further technological innovation for yet more exploitation of resources.

Subsistence intensification effectively improves an environment’s carrying capacity, at which point the passion between the sexes once again begins to assure an increase in the birth rate and size of a population. The deployment of new technology to increase rates of available resource productivity so as to feed the additional people enables a larger population to exist. But at the same time it also tends to present new challenges such as increased production risks, warfare and raiding, inefficiency of resource use, and further resource deficiencies. The use of technology to exploit available resources tends to exacerbate the stress on the scarce, immediately available and relatively easy to acquire resources necessary for survival. When this stress occurs, the larger population predictably turns to a greater variety of less and less efficient local resources in order to meet its subsistence needs, thus tending to deplete the buffer available for surviving in lean times. In turn, when the buffer gets small enough, starvation becomes a palpable danger that demands strategies to manage that risk. At that point, growth-oriented cultures need to acquire additional stores of resources or they fall into decline.

When a growing settlement begins to reach the limit of subsistence intensification within the constraints of its own local setting, a second strategy to support growth could emerge. The second strategy is known as integration. Growing settlements can acquire access to additional resources by engaging in some mixture of two integrative behaviors. The first is peaceable trade with other nearby settlements. Every settlement that grows beyond its own initial setting and evolves into a broader civilization establishes a complex series of trade and cultural communication ties among a network of nearby settlements. Some ties are established over land routes. Others arise by water routes. Voluntary trade with other settlements allows a growth-oriented culture to grow beyond the limitations of subsistence intensification . But integration has not always been voluntary. Reluctant trading partners have often been invaded and conquered, and their resources plundered. The survivors have at times been wiped out systematically, and at others, they have been assimilated by force into the culture of the victors. Similarly, conquered settlements have at times been destroyed, and at other times occupied, rebuilt, and colonized. Both behaviors change how individuals and groups of different sizes and complexities interrelate at both social and systemic levels (Lockwood 1964).

There are many different scales of integration, both voluntary and involuntary . For instance, families integrate when they form camps of four to six families. Camps integrate when they form regional networks. Regional networks integrate when they form multiregional polities. Multiregional polities integrate when the form states with bureaucracies and military organizations . Settlements integrate when they form civilizations. All such integration has two aspects: social and systemic. Its social aspects involve things such as increased bonds of social attraction, greater degrees of cohesion and interdependence between individuals, and an increased readiness of individuals to engage in social intercourse with one another (Blau 1960). Its systemic aspects involve things such as rearranging economic, political, legal, and/or religious institutions through which traditional sources of authority are exercised. Systemic integration can be encouraged by newly invented technologies, especially those related to transportation and/or communication. It can also be stimulated by environmental changes that create new reasons for growing populations to reorganize and expand their social relationships.

New types of political and economic systems have always arisen as a direct result of integrative behaviors. Small bands of people and small agricultural villages evolved into local groups such as tribes and chiefdoms and then evolved further from local groups to regional polities such as kingdoms, city-states, and nation-states. The twentieth century saw the evolution, for example, of new globalized institutions such as the United Nations, the World Bank , and the International Monetary Fund . Systemic integration has occurred across geographic regions, states, and countries. Integration is what happened, for example, when the ancient Romans conquered regions in Europe, the Middle East, and Northern Africa, and relatively recently the nations of Europe voluntarily integrated into the European Union . Systemic integration can also occur across communication channels, networks of social authority, and through the development of new forms of cooperative linkages, such as modern-day mergers and acquisitions of international corporations or the consolidation of universities. 2

In any of its forms, the post-integrated system includes a more complex multilevel structure of control which allows more complicated forms of behavior and interaction among the members of the initially pre-integrated groups. Such is a civilization. The two or more groups become partially or wholly rearranged to form a larger and more complex institutional system. Current examples of mechanisms supportive of further systemic integration include two-way preferential trade agreements, free trade agreements, customs unions, common markets, foreign direct investments, and political and economic unions.

Integration is a key strategy for overcoming the challenges posed by population growth. According to Johnson and Earle (2000: 328):

Integration on a massive regional or interregional scale is a defining characteristic of states. Minimally, this integration involves a bureaucracy, a military establishment, and an institutionalized state religion. These institutions ensure the state adequate finance, capable economic management, stability, and legitimacy. Over and above these fundamentally political institutions, the establishment of regional peace by a powerful state permits a rapid increase in economic integration, either through the development of markets and trade, as in medieval France and Japan, or in the extension of community territories to incorporate diverse production systems, as in the case of the Inkas.

Integration also tends to create more complex social systems because it requires greater levels of specialization and exchange, higher levels of centralized risk management, and more advanced technology to enable communication networks for purposes of establishing hierarchical control of the post-integrated system.

A third commonly used strategy for responding to population growth is social stratification. This involves institutionalized systems of hierarchically ranked relationships in which individuals, groups of individuals, segments of settlements, and often entire settlements within a larger culture are assigned to lower or higher rank depending upon the category into which they are placed by the culture’s elites. These specific contours and boundaries of different categories are typically defined by a culture’s dominant forms of traditional source authority, i.e., violence, heredity, gender, religion, and knowledge. Thousands of elaborate and nuanced systems have evolved over the millennia.

In its oldest forms, stratification systems designate some individuals as “big men,” chiefs, or leaders of entire civilizations. These leaders exercise power to give orders to pursue subsistence intensification for purposes such as controlling centralized stores of resources, organizing centralized exchange, and implementing technologies that are expected to be more productive, and mediating or arbitrating internal conflicts. Others follow the leader’s orders and obey. These are stratified groups. In stratified systems, some individuals are assigned membership in the category of king, emperor, chief, or ruler, while others were assigned to the categories that were expected to follow or be ruled by them. Countless variations of stratified cultures have emerged, often creating and perpetuating invidious myths about the superiority of one category relative to another. As populations grow, people in higher categories often avoid contact with those in lower categories. Especially, when issues arise about control over scarce land within settlements, stratification gets reflected in patterns of residential segregation, as well as differential access to amenities, educational opportunities, and opportunities for achievement. Virtually without exception, once a settlement system becomes sufficiently large and complex, social stratification is a characteristic feature that allows it to achieve subsistence intensification . And once a settlement system becomes integrated into a larger civilization, the stratification system takes on a geographical structure that differentiates some places as more “central” than others and relegates other places to the lower status. In the walled cities of Medieval Europe, for instance, the lower status places would be located outside of the city wall. In contemporary cities, the lower status places are urban slums.

A number of perspectives have been advanced regarding whether social stratification is a universal but variable trait of human societies, on the one hand, or not the standard among all societies, on the other. For instance, having examined a substantial body of ethnographic data about the causes, mechanisms, and patterns of cultural evolution and growth in the scale and complexity of human societies, Johnson and Earle (2000: 329) concluded:

All states are stratified. They have to be, because the very institutions of state that are necessary to prevent economic chaos are based on a reliable income for finance. This income is possible only with economic control, and that control translates into rule by an elite, whether socially, politically, or religiously marked. At the state level, stratification appears to be inevitable. The socialistic and democratic alternatives seem only to decorate a fundamental stratification with an ideology of egalitarianism. As much as we cringe from this conclusion, the only alternative would be a comprehensive simplification of world economic problems that is impossible with pressing populations.

This is consistent with the point of view of general systems theory in which increases in complexity generally take the form of increases in hierarchy. It has been argued that complexity is hierarchical and that hierarchy is “one of the central structural schemes that the architect of complexity uses” (Simon 1962: 468). Certainly, social hierarchies may be readily observed throughout other biological systems ranging from colonies of ants to broods of chicks to packs of wolves to groups of chimpanzees. As well, social hierarchies may be observed within a wide range of formal human social organizations from universities to governments to business and nonprofit firms, to militaries and religious organizations . But hierarchies in human settlement systems are common beyond this too. Aside from the hierarchies within families, even the smallest and least complex levels of human settlements such as hamlets and villages tend to institutionalize leadership positions such as chiefs, priests, and big men who control the surplus taken from the subsistence economy for the well-being of the settlement population as a whole. Moreover, as the size and complexity of settlement systems increase, so do opportunities for hierarchical political and economic control not only of the subsistence economy but also of excesses of goods typically channeled for use by the upper social strata, and particularly the ruling elite. Sufficient complexity had already developed in the ancient Greek city-states for hierarchies of cities as described by Central Place Theory to have emerged (Pounds 1969).

Intensification, integration, and stratification are historically and geographically pronounced strategies that have been used predictably to respond to population growth throughout the evolution of human settlements . The development of virtually any civilization in history can be described through an historical account of its population growth, leading to intensification, leading to integration and stratification. The cycle was also repetitive—the feedback between technological innovation and population growth set the stage time and again for technical and social innovation. As our ancestral foraging groups turned into villages and later fiefdoms became larger polities and entire civilizations, the evolutionary mechanisms were intensification, integration, and social stratification. Each time, change and development was precipitated by the feedback between population growth and technological innovation . Intensification begat integration begat stratification. Intensification created problems of population growth which were, in turn, solved through innovation and integration. In each case, the solution created a demand for leadership or control that was met by some alteration of social relations . The great irony, however, is that the evolving cycle of intensification-integration-and stratification in any particular case always at some point hit a level of population growth beyond which it suffered the fate of decreasing ability to use intensification and integration to solve the challenge of producing enough surplus on a per capita basis to maintain its rate of population growth. The result of hitting that barrier meant that decline would set in.

Each sequential stage in the evolutionary cycle solves or diffuses certain problems of the previous stage, but the cycle does not annul or put an end to them. At the same time, as each new stage solves some problems of the previous one, it necessarily brings its own and new problems that were not present in its predecessors, some of which are apt to be more difficult and recalcitrant than the previous ones. For example, when among other places, hunter-gatherers started to become sedentary and develop village agriculture in that part of the Near East we call “the Fertile Crescent ,” they solved the problem of food shortages brought on by a one-thousand-year long drought that made their previous lifeway impossible. But in doing so they also established the means to solve the problem of growing enough of a stable food supply to feed more children, which allowed their population to increase. The growing need to feed more people then committed them to a more sedentary lifestyle in order to grow, harvest, and prepare the greater bulk of agricultural food products needed to satisfy more hungry people. This led to the need to create more elaborate social hierarchies that had leaders and chiefs who would possess enough power to control the centralized stores of grain necessary for surviving droughts, winters, and other periods of time when agricultural production was not adequate. For reasons of individual and collective survival, through one cycle after another, they continually traded one set of problems for another.

The ancient Egyptians had a similar experience. Their civilization developed along the banks of the Nile River, which is about 750 miles long, but only 5–15 miles wide. Evidence of village agriculture there dates back as far as 7000 bc. As early as 5000 bc, small agrarian communities began to drain marshes, irrigate, and plant regular crops (mainly cereal grains). The irrigation dramatically increased agricultural productivity, after which they had a population boom. This led to problems that they met through integration of many small villages distributed all along the Nile into the larger whole of Egypt. The ubiquitous granaries in ancient Egyptian ruins suggest that the integrated population collectively managed the risk of starvation centrally, through communal food storage. The integrated system also provided for common defense against raids which, fortunately for them, by virtue of the Nile valley’s significant geographical defenses, were in any case quite rare. But the irrigation system required maintenance and expansion, and so the integrated system required centralized control. Ritual systems and political authority evolved. Social strata were set up with farmers and laborers on the bottom, immediately below the artisans, followed sequentially by the scribes, the district governors, the royal overseers, the viziers and high priests, and finally the pharaoh. The centralized administration levied new taxes on the population by virtue of the Nile valley’s significant geographical defenses. The elite office of pharaoh controlled the disposition of the harvest, organized and administered its storage in granaries, maintained, and expanded the irrigation system, and administered the robust land and sea trade networks used to shore up resource deficiencies.

The pattern is in many ways typical. Individuals and groups in settlement systems have always had insufficient natural and productive resources to fulfill all of the wants and needs of their inhabitants. They’ve always lived in some degree within a context of scarcity. They’ve had to derive their subsistence and other needs and wants from their surrounding habitat together with whatever resources the transportation technology at the time would allow them to transport and trade. When the resources necessary to meet the population’s subsistence needs have allowed, passion between the sexes has led to population growth to a point at which the resource base has started to become inadequate for purposes of supporting the additional people. Once the easy-to-acquire resources have started to deplete, increasing pressure from the additional increments to the population has started to give rise to increasing pressures for technological innovation . New technologies have been needed specifically to gain access to resources that were previously either inaccessible or too expensive to acquire. This pressure led to technological advancement which enabled more efficient exploitation of the resources required to support the subsistence economy, thus increasing the available supply of subsistence resources and also allowing for still-further population growth. A cycle has thus set up in which the sustainability of the then-current population has been based upon the maintenance of a positive feedback loop between population growth and technological advancement. On the one hand, population growth has predictably led to more technological advancement. On the other, more technological advancement has predictably led to more population growth, and so on and so forth. This interaction between pollution growth and technological advancement has been driven by pressures for innovation brought about by efforts to improve resource productivity for purposes of meeting the tissue needs of the growing population. Additional energy sources have also almost invariably been required to support the loop.

The growth and development of human settlement systems has virtually always gone hand in hand with this sort of dynamic interplay between population growth and technological innovation , and it has virtually always occurred within a context of scarcity. Resource scarcity has been a constant—no settlement system or civilization in history has escaped the problems it poses, and none are likely to do so in the foreseeable future. Population growth in a given settlement system increases pressures for subsistence resources from the immediately accessible environment. There are more mouths to feed. But because as a result of these additional mouths, food and the other resources necessary for subsistence eventually start to become depleted, at which point population growth begins to slow down or stop. The point at which the available resource base can no longer support further population is the “carrying capacity” of that environment. 3 When the carrying capacity is reached, the ecological limits on subsistence productivity, as determined by the particular population’s environment, tends to effectively cap further growth of the population. For instance, the food or water supplies may become a limiting factor, as may supplies of energy, nutrients, or minerals. Parasites and diseases may emerge, including some that are resistant to antibiotics, temperatures, and weather conditions may become inhospitable for life, a lack of space may occur, or warfare may arise in competition for limited resources. In any case, when the population approaches the carrying capacity, birth rates begin to decline, and death rates begin to increase, leading to a decrease in the growth rate of the population. Or, in some cases, death rates may increase dramatically, in which case the population collapses.

About 2000 years ago, the cycle of growth and decline in civilizations reached a scale that had not been achieved previously. In Europe, North Africa, and the Near East, the Roman system had expanded around the dense network of regional trade routes that were made possible by the Mediterranean Sea. In China, the Han world had expanded around the dense network of regional roads and the widespread network of tributaries that fed into the two great water systems of the Yellow River and the Yangtze River . These two ancient expansive cultures grew large enough to be aware of each other’s existence. Yet there was only a limited amount of overland trade between them, facilitated by long-distance overland trade patterns. Along those, trade patterns were also a series of growing cultures through India and Persia, among others. At the same time, there were at least several large-scale, long-established, prosperous cultures in the Americas, in Mesoamerica and in the Andes mountain chain. Likewise, these cultures were aware of each other even though they did not interact directly. In Africa, the ongoing waves of migration among Bantu people were establishing strong local cultures marked by trade and growth. And in Southeast Asia, the Funan culture (often thought of as the first Khmer culture) had begun to emerge as an important regional culture.

As discussed earlier, the Roman world and the Han Chinese world each supported more than 50 million people. The different cultures in the Americas likewise supported tens of millions of people. So too did the cultures on the Indian subcontinent, Southeast Asia, the Persians, and the Bantu. After 300,000 years of persistence, modern people achieved a population peak of almost 200 million living individuals by about two thousand years ago. But that global growth cycle did not last. Within a few centuries, the largest of these cultures dissipated, cities collapsed, trade declined sharply, and global population growth stalled once again. The inexorable constraints of the elementary population growth equation were not yet overcome.

Notes

  1. 1.

    A small sample could include Toynbee (1946), Fukuyama (1992), Huntington (1997), Mumford (1961), Kostof (1991), and Morris (1994).

  2. 2.

    Integration always involves some degree of unification of two or more cooperative human groups (say, Gi = G1, G2, G3, …Gn) into a single larger group (call it Gi ← Gi') that includes the initial groups as well as an additional mechanism for control of their collective behaviors.

  3. 3.

    The carrying capacity is the number of people, other living organisms, or crops that a region can support without environmental degradation. For insight and detail, see Arrow et al. (1998).