regarded as having been subsets of agrarian societies.
There is, unfortunately, a powerful temptation in modern sociology to ig- nore such questions, or to resolve them by recourse to statistical analysis. Neither of these “solutions” is satisfactory, however, because the problem is too important to be ignored and the quantitative data we possess are not adequate to the task of resolving the issue statistically (i.e., the relationships are only correlational). The solution lies instead, I believe, with the careful development of a general theory of societal adaptation and evolution and with an equally careful examination of all of
the relevant data—nonquantitative as well as quantitative.
Dependent Variables: Characteristics of the Global System of
Societies
Last, but by no means least, ecological-evolutionary theory must explain and pre- dict the important features of the global system of societies. As indicated above, this is not simply another set of societies. Unlike the sets we have just considered, the world system is more than an analytical construct: As its name indicates, it is a functioning system composed of interactive parts—namely, individual societies.
Two striking characteristics of the global system are (a) the extent to which it has been transformed and (b) the temporal pattern of this process. Prior to the modern era, most societies had direct and sustained contact with only a small number of neighboring societies; relations with more distant societies were indirect and mediated by intervening societies. Now, however, thanks to revolutionary advances in the technologies of transportation and communication made in the last cen- tury, most societies interact directly and in a sustained way with most other soci- eties.
Much of the change in the global system is impossible to quantify, but there are important exceptions. For example, we now have reasonably accurate esti- mates of world population at several scattered points in history. One of these is the end of the hunting and gathering era, roughly 10,000 years ago. Estimates for this period are based on information about the extent of the territories inhabited at the time and their carrying capacity, with the latter based on numerous obser- vations of modern hunting and gathering peoples living under similar conditions. The best estimates today range from 3 to 9 million. By the beginning of the Christian era, 8,000 years later, world population had grown to approximately 300 million, and during the next 1,700 years, by the eve of the Industrial Revolu- tion, it grew to 750 million. Now, hardly more than 300 years later, it is over 6 billion and growing at a rate of approximately 75 million per year! Indeed, as these figures indicate, for most of the last 10,000 years (see Table 2.1) human population has been increasing at an exponential rate.
Energy consumption is another fundamental feature of the world system for which there are reasonably good estimates. Prior to the discovery of the uses of fire around 500,000 B.P. (Before the Present), food was the only source of energy in human societies. Assuming an average individual consumption of 2,000 calo- ries per day by a population numbering half a million (a generous estimate for the time; see Hassan, 1981: ch. 12), we arrive at an estimate of energy consumption for the entire human population of 109 calories per day. Harrison Brown (1954)
calculated that the use of fire and the domestication of animals (beginning about 10,000 B.P.) raised the daily consumption of energy for a part of the world’s popu- lation to about 10,000 calories per day. Thus, by the start of the Christian era,
Table 2.1. The Growth of Human Population, 8000 B.C. to 2000 A.D.
Date Population 8000 B.C. 3–9,000,000 1 A.D. 300,000,000 1650 A.D. 545,000,000 1750 A.D. 750,000,000 1850 A.D. 1,170,000,000 1950 A.D. 2,500,000,000 2000 A.D. 6,075,000,000
Sources: Dumond (1975); Hassan (1981); Grauman (1968); Statistical Abstract of the United States, 2002.
Problem and Method 27 1014 1012 1010 108 106 104 102 10 1014 1012 1010 108 106 104 102 10 4–500,000 before present 500,000 B.P. 400,000 B.P. 300,000 B.P. 200,000 B.P. 100,000 B.P. 18,000 B.P 2,000 A.D. World Population
World energy consumption
when the use of fire in human societies was virtually universal and animal domes- tication was practiced by a substantial percentage of societies, world energy con- sumption must have totaled approximately 2.5 x 1012 calories per day, or roughly
2,500 times the amount consumed 500 millennia earlier. Finally, individual con- sumption currently averages 50,000 calories per day worldwide, or 2.3 x 1014
calories per day—nearly a hundred-fold increase in just the last 2,000 years and more than a two hundred thousand-fold increase in the last 10,000 years.
Plotting these values graphically (see Figure 2.1), we see how the explosive acceleration in the rate of world energy consumption and population growth in the last 10,000 years, and especially in the last 200 years, brought to an end the pattern of gradual change that had prevailed for hundreds of millennia. The rapid nature of this acceleration, it should be noted, is understated visually in the dia- gram because of the logarithmic transformations of the measures of world popu- lation and world energy consumption. Without these transformations, it would be all but impossible to graph the trends on a normal-sized page. In interpreting Figure 2.1, the reader should also keep in mind that the trend lines cover only the most recent 10 to 12 percent of hominid history. If the trend lines were carried back to the point where our ancestral line had its beginnings 4–5 million years ago (i.e., if the figure were eight to ten times wider than it is), these lines would come close to the bottom of the chart. This is a further reminder of the unique character of the recent past.
The pattern of slow and gradual change over millions of years, followed by an explosive rate of change in recent millennia, is evident also in a number of other areas where quantification is much more difficult or impossible. The trend in the production of goods and services, for example, closely parallels that of energy consumption, since levels of production are highly correlated with the
Figure 2.1 Log of world population and log of world energy consumption from 500,000
amounts of energy consumed. Not surprisingly, these trends are paralleled by trends in the accumulation of wealth in general and of capital goods in particular. Their rate of increase has been especially explosive in recent millennia, since accumula- tion was all but impossible until the beginnings of plant cultivation allowed for a more settled way of life. And, finally, the volume of illth, or waste and injurious products (e.g., harmful drugs), has also grown exponentially in recent times.
Many important trends did not even commence until the last few thousand years. For example, the first urban settlements (i.e., communities in which the majority of residents are free of the necessity of producing their own food and fibers) do not appear in the archaeological record until the last 8,000 to 9,000 years, and until recently their growth was slow. The best available evidence sug- gests that as recently as 200 years ago, no more than 5 percent of the human population lived in such communities, with the largest having a population of only about a million. Today, in contrast, nearly half of the world’s population lives in urban communities, the largest of which, Tokyo, now has more than 34 mil- lion inhabitants.
The rise and spread of urban communities is closely linked to other impor- tant trends. Writing and monetary systems, for example, are both products of urban life, though neither appeared until thousands of years after the first urban settlements. The increase in the division of labor is another trend that has been largely dependent on the expansion of urban settlements. Judging from archaeo- logical evidence, and from studies of nonurban societies that have survived into the modern era, it appears that, prior to the emergence of the first towns and cities, occupational specialization was based mainly on age and sex distinctions. Occasionally, preurban societies have had headmen and shamans who performed specialized tasks on a part-time basis, but specialization rarely went beyond this. In contrast, urban communities, from the outset, utilized full-time specialists of various kinds, ranging from religious and political functionaries to artisans, merchants, soldiers, and household servants. Since the beginning of the Industrial Revolution, occupational specialization has increased enormously. Although there is no measure of the extent of occupational specialization in the global system as a whole, the U.S. Department of Labor has identified more than 20,000 full-time occupational specialties in this one society alone.
The expansion of the division of labor is not merely a matter of increased occupational specialization, however. It also takes the form of increased organiza- tional, regional, and even societal specialization. Over time, an extraordinarily complex division of labor has developed among both specialized associations (e.g., labor unions, universities, churches) and communities (e.g., political centers, re- sort communities, fishing villages, university towns). Regional and societal spe- cialization is largely economic in nature, with different regions within societies, and different societies within the global system, specializing in the production of various types of goods and services. Communal and societal specialization have roots that go back to the hunting and gathering era, as indicated by archaeological evidence of early intersocietal trade. Associational specialization is more recent,
Problem and Method 29 and has been dependent on the rise of towns and cities. In all cases, however, the degree of specialization has risen exponentially, with the most dramatic increases occurring in the recent past.
The enormous increase in the division of labor within societies has been possible only because of the increased size of societies themselves. Prior to the beginnings of horticulture, the largest human settlement of which we have knowl- edge had an apparent population of 400 to 600 (Pfeiffer, l978). Because of its location, however, it appears that this was merely a temporary convergence of several different societies that were attracted to the site by a rich seasonal salmon run. Studies of hunting and gathering societies of the modern era indicate that their populations have averaged no more than 25 to 50 (Hassan, 1981: ch. 6; Lenski et al., l995: table 5.3), and rarely numbered as many as 100. Based on all we know about these groups, it seems unlikely that the limits on growth were very different in the past (Hassan, 1981: ch. 6).
Since the beginnings of horticulture, however, the average size of societies has steadily increased, with the increase having been especially pronounced since the rise and spread of industrialization. Today, the populations of societies average 20 to 30 million. This growth in numbers has been paralleled by growth in terri- torial size and in organizational complexity.
Not every sociologically important variable, however, is characterized by a pattern of continuing and exponential growth. One extremely important excep- tion is the number of societies themselves. Prior to the beginnings of plant culti- vation 9,000 years ago, the trend was upward, so far as one can judge today. This was due to the more or less continuous spread of human population into new territories and a process of frequent societal fission. This upward trend was almost certainly an irregular one in which periods of relative stability were punctuated periodically by surges following the initial entry of human groups into vast new territories, such as the Americas and Australia.
This upward trend was finally reversed sometime in the last 10,000 years as the process of forming multicommunity societies began and an ever-increasing number of smaller societies were conquered by, or otherwise absorbed into, more expansive neighbors. This trend has continued to the present day, with the result that the 100,000 or more societies into which the world system was divided just 9,000 years ago has been reduced to fewer than 300 today.2 As we shall see in
2. No one knows exactly how many societies were in existence at the end of the Paleolithic, but modern estimates of the human population at that time, based on knowledge of the areas occu- pied and the levels of population density possible in hunting and gathering societies, indicate num- bers in the range of 3 to 9 million, as noted earlier. In addition, modern studies of societies dependent wholly or largely on hunting and gathering indicate an average size of 25 to 30. Putting these figures together, we arrive at an estimate of 100,000 to 300,000 societies around 8,000 B.C. Since then, the
number of societies has shrunk dramatically. There are today less than 200 independent nation-states and perhaps another 50 to 100 small, preliterate groups that still enjoy sufficient political autonomy to justify classifying them as societies.
Chapter 6, this development has been of critical importance to the overall trans- formation of the global system.
Another reversal of note is the declining level of intrasocietal inequality that has been associated with the rise and spread of industrialism in the last 100 years. Since early in the horticultural era, societal growth and development was always linked with increases in inequality within societies. Horticultural societies, for instance, were less egalitarian than hunting and gathering societies, and inequali- ties in agrarian societies were even more pronounced.
Had this trend continued, the level of inequality in modern industrial soci- eties would have become substantially greater than in agrarian societies. This has not happened, however. Inequalities in the distribution of income and wealth (as measured by the Gini Index and similar measures of overall distribution) in ad- vanced industrial societies, though enormous, are less than they were in agrarian societies of the past and still are in industrializing agrarian societies today. Political inequality, too, though still substantial, has been significantly reduced in all in- dustrial societies.
Within the last quarter-century there has been an important reversal in an- other historic trend: A decline in the rate of population growth, begun in the late 1960s, promises to be the beginning of a new long-term trend. During the period from roughly 2,000,000 B.P. to about 10,000 B.P., the rate of population growth appears to have increased gradually from 0.00007 to 0.00150 percent per year (Dumond, 1975: 717). From 10,000 B.P. to 1960 A.D., the rate of growth in- creased much more rapidly, and by the early 1960s world population was increas- ing annually at a rate of 2.0 percent. Since then it has dropped back to a level of 1.2 percent. Given the many problems that population growth creates and the technological resources now available for controlling it, it seems unlikely that the long-term trend will again be reversed. In fact, one can now even begin to con- template the possibility of a reversal in the growth of world population itself, and not simply in its rate of increase.
Another recent reversal involves the extent of societal diversity. For most of the last 10,000 years, human societies have grown increasingly varied, especially in terms of size and complexity (see Figure 2.2). Now, however, the point has been reached where all of the smallest and least complex societies seem destined for extinction. In fact, it seems unlikely that any reasonably pure hunting and gather- ing society (i.e., one that is substantially unmodified by contact with more ad- vanced societies) still survives intact, and the future for other preliterate societies is not much brighter.
Having emphasized the change that has occurred in the global system, it is necessary to emphasize once again the importance of continuity in the human record. During the vast span of the Lower Paleolithic that encompassed all but the last 2.5 percent of hominid history, there was what one writer (Hawkes, 1963) has called an “almost unimaginable slowness of change.” Patterns of life in the global system, insofar as they can be inferred from the archaeological record, persisted not merely for centuries and millennia, but for tens and hundreds of millennia.
Problem and Method 31
In the last 10,000 years, the dramatic increase in the rate of change has tended to obscure the still-widespread evidence of continuity, yet tangible proof of it is all around us. Social institutions such as marriage, the nuclear family, government, and religion can all be traced back to the earliest of written records, and many have persisted far longer. Social roles such as husband, mother, priest, king, artisan, and servant have endured for millennia, and we still use many of the same kinds of tools—hammers, axes, knives, and saws—as did our distant ances- tors. These serve as a powerful reminder of the essentially cumulative nature of the evolutionary process itself, a process by which older, simpler elements of social and cultural systems are absorbed and incorporated into newer, more complex systems. Thus, even supersonic jet airplanes, a classic symbol of innovation and modernity, incorporate many ancient elements, including the basic principles of metallurgy, the wheel, the chair, the window, the handle, numbers, letters, and more. Similar examples abound. For this reason, it is a great mistake to think of the
rate of continuity as the inverse of the rate of change where evolutionary processes are involved.