Ecological-evolutionary theory begins with Malthus. It was Malthus who insisted that human societies have  

There is great need of a perspective to integrate the diverse findings of the social sciences.  This need certainly exists among practitioners of the craft.  Without theory we collect facts and “middle range” theories without end, we lose focus and coherence. Theory should guide research agendas, informing us what to look for (and where to look); how to interpret the “facts”--which never really speak for themselves; further our understanding of sociocultural systems, not simply add to the confusion. The need for holistic theory is also present among our students (whether they realize it or not), many of whom despair of understanding the social world around them, though they sometimes come to sociology and anthropology in hopes of achieving such a perspective (and only rarely find it).  We are doing a grave disservice to students when we simply present them with factual relationships with no interpretive guidelines, no overarching vision.  Finally, the need for a social science perspective exists in society at large --members of a democratic society must understand sociocultural systems and the dynamics of these systems if democracy is to thrive. 

While there is a widespread recognition of this need for vision on the part of sociologists and anthropologists, there is not much agreement on what that vision should be.  To be effective, a successful perspective must be powerful, integrative, simple, and comprehensive in scope.  There are only a few contemporary perspectives in sociology and anthropology today that even attempt to provide such a holistic perspective--try to account for the origin, maintenance and change of sociocultural systems. Increasingly our texts advocate “eclecticism,” explaining social relationships with any middle-range theory at hand--a prescription for scientific disaster.  This essay 

II
Macro-perspectives have largely fallen into disuse in the social sciences since the 19th century--trotted out in our introductory texts, and then largely ignored (except, perhaps, as an afterthought).  Ecological-evolutionary theory is different, however.  It is capable of providing both coherence and integration of the disciplines, it is capable of furthering our understanding of sociocultural systems.
Gerhard and Jean Lenski present an evolutionary-ecological theory as an integrating device, synthesizing both the classical works of sociologists and anthropologists and contemporary social theory and findings.  In their acknowledgments in the preface to their 5th edition of Human Societies, the Lenski’s acknowledge their intellectual debt to many social scientists, Malthus being the first among them (1987: xv). The Lenskis present an ecological- evolutionary theory of social organization and change--and as they acknowledge, Malthus has profoundly influenced it.

The foundation of Lensi's ecological-evolutionary theory is the observation that human societies are part of the world of nature.  Human societies are subject to natural law. Sociocultural systems can only be fully understood as being responsive to the interactions of populations to their environments (1987: 55).  At the base of their perspective lies the relationship between population and production.  Like all life forms humans have a reproductive capacity that substantially exceeds the necessary subsistence resources in the environment.  Thus, they conclude, human populations tend to grow unless they are checked (1987: 32).  The checks, of course, consist of both the positive and preventive checks that Malthus examined.  The capacity for population growth, the Lenski’s assert, has been a “profoundly destabilizing force throughout human history and may well be the ultimate source of most social and cultural change” (1987: 32). The Lenski’s posit that population-production-environment relationships drive the evolution of sociocultural systems. 

The influence of Malthus is also clearly apparent when the Lenski’s discuss the nature of social inequality.  They assert that we are social animals obliged to cooperate with one another in producing a living (1966: 24).  But, like Malthus, they also claim that human beings are strongly motivated by self-interests.  The Lenskis state: “when men are confronted with important decisions where they are obliged to choose between their own, or their group’s, interests and the interests of others, they nearly always choose the former--though often seeking to hide this fact from themselves and others” (emphasis in the original, 1966: 30).  Since most necessary resources are in short supply, they continue, a struggle for rewards will be present in every human society.  Individuals are born with a range of innate abilities and circumstances.  Thus the root of social inequality is in our nature.  Some minimal distribution of wealth is necessary to ensure the survival of  “others whose actions are necessary” to themselves, but any surplus (goods and services over and above the minimum required to keep necessary workers alive and productive) will be distributed unequally (1966: 44-45). 

In the earlier stages of sociocultural evolution the distribution of resources is allocated on the basis of personal characteristics--hunting skills or plant gathering productivity.  With the development of a more complex division of labor these inequalities become institutionalized in class, caste, race, sex, and ethnic systems.  Thus, like Malthus before them, they conclude that inequality is inevitable in any complex sociocultural system (complex as measured by a division of labor)--though the degree of inequality is variable across societies and through time (1966: 442). 

Though population-production-ecological relationships are at the base of the Lenski’s system, their theory tends to incorporate numerous explanatory relationships within these broad confines. The Lenski’s developed their general ecological-evolutionary theory as an integrating device for the diverse insights of many classical theorists and contemporary observers.  A particular brand of ecological-evolutionary theory, that of Marvin Harris’s cultural materialism, has been developed as an alternative analytical system.  Unlike the Lenski’s, who have been significantly influenced by numerous classical theorists, Harris’ theory is truly beholden to only two--Malthus and Marx.

III
The influence of Malthus is arguably the dominant source of Harris’s cultural materialism. For Harris, like Malthus, it is self-interests that motivate human beings (1979: 60-64).  For Harris, again like Malthus, self-interest encompasses more than simple cost/benefit economic calculations.  Harris defines four basic “bio-psychological needs” of individuals that motivate human activity.  Two of these needs, the need to eat and the need for sex, are shared out-right with Malthus’ basic assumptions.  A third motivating factor enumerated by Harris, the need for love and affection, is implicit in Malthus’ analyses (as evidenced by his concern for “happiness” and the importance he attributes to bonds between husband and wife, and children).  Finally, Harris's fourth need, the desire to conserve human energy, is not directly present in the Malthusian system.  But Malthus does frequently state that without the goad of necessity, human activity and striving to better one’s condition will erode, thus implying that people will act to conserve their human energy in important cost-benefit decisions. 

According to Harris, It is through pursuing cost/benefit options—adaptive changes in the activity and thought of individual human beings in their attempts to meet their bio-psychological needs—that provide the driving force of sociocultural change. Both Harris and Malthus are in agreement that it is the perceived self-interests of individuals—particularly as regarding children, work, and standard of living—that determine whether or not measures are taken to prevent births. 

It is not the “greatest” bio-psychological good for the greatest number of people, however, that determines the evolution of sociocultural systems.  Harris posits the existence of elites in every society—elites whose interests “weigh more heavily in the balance of advantages and disadvantages” in adapting or rejecting social innovation (1979: 61).  These elites are based on class, sex, and ethinic hierarchies.  The amount of power the elite wield, however, varies across societies and through time (1979: 61-62). 
The foundation of Harris’ theory is that a society’s mode of production (technology and work patterns, especially in regard to food) and mode of reproduction (population level and growth) in interaction with the natural environment has profound effects on sociocultural stability and change.  He notes that over the long haul increasing productivity and population growth are linked (1979: 67).  Early adoption of technology was not used to increase the living standards of the bulk of the population—through the 19th century people worked more hours and had a lower standard of living (as measured by nutrition, health, and longevity) despite the adoption of more efficient technology.  Harris then asks why productivity and population are linked, and provides a very Malthusian explanation.

Malthus, Harris reports, correctly perceived that population has been checked throughout the pre-industrial era through positive checks.  Re-labeling these positive checks as “malign population regulating techniques,” Harris writes that they involve such practices as infanticide, body-trauma abortion, and nutritional neglect of infants.  Harris also points to some “benign techniques” (similar to Malthus’ “preventive checks”) available to pre-industrial populations—such as homosexuality, coitus interruptus, and delayed marriage.  But, Harris asserts, the evidence of preventive checks in pre-industrial populations cannot explain the “remarkably slow” growth of population in the pre-industrial era.  For hundreds of thousands of years before agriculture the growth of human populations was .0007 percent--a doubling time measured in thousands of years, rather than the inherent capacity of healthy human populations to double every 25 years (the 25 year estimate of Malthus is consistent with modern day estimates). It is apparent, Harris claims, that pre-industrial peoples kept their numbers in line primarily through positive checks. Assuming that the amount of food gathered and hunted by these societies was constant, Harris estimates that fully 50 percent of all females born were prevented from reaching reproductive age.  “In other words, because prehistoric cultures kept their numbers in line with what they could afford by killing or neglecting their own children, they were vulnerable to the lure of innovations that seemed likely to allow more children to live” (1979: 69). 

The relationships between productivity and population— both Malthusian preoccupations—form the heart of Harris’ cultural materialism theory.  The Malthusian costs of keeping population in line with what technology-environmental relationships will sustain, can account for both institutional structures and widespread cultural beliefs of pre-industrial societies.  Societies are systems, Harris asserts, and widespread social practices and beliefs must be compatible with the infrastructure of society (the modes of production and reproduction and their interaction with the environment).  The infrastructure represents the ways in which a society regulates both the type and amount of resources needed to sustain the society.  A good deal of Harris’ work, therefore, is concerned with explaining cultural systems (norms, ideologies, values, beliefs) and widespread social institutions and practices through the use of population, production, and ecological variables—an explicit functional analysis of sociocultural systems that again mirrors Malthus (Harris, 1977, 1978, & 1981).

Harris apparently believes Malthus’ theory of poverty underestimates structural inequality (exploitation due to the existence of elites)—at least in terms of a theory of sufficient generality to encompass all human societies.  Harris claims that the amount of inequality due to elite exploitation and the amount due to population growth—like the extent of the power of elites themselves—probably depend upon a variety of factors of the sociocultural system, and are therefore an empirical question (1979: 74).  But both men are in apparent agreement that two of the major factors that contribute to inequality are elite dominance and population growth (and both add structural elite interests that encourage population growth in order to hold down the cost of labor and expand internal markets).  Of these two factors, Malthus puts the most weight on population growth itself.  While Malthus clearly recognizes the existence of exploitative elites in society he never systematically incorporated this insight into his general theory (p. 145 & p. 169).  Harris, as a Neo-Malthusian influenced by other social theorists (particularly Marx), integrates both population and structural elites into his theory of cultural materialism.

One significant difference between Harris and Malthus lies in their treatment of birth control in the modern era.  While Harris asserts that there are structural and ideological components to preventive population control—such phenomenon as delayed marriage and abstinence—there is also an increasing technological component.  Unlike Malthus, Harris explicitly and systematically explores the increasing availability of birth control technology as a way for people to more efficiently control their fertility.  Harris claims that the development of the technology of population control plays a central role in the evolution of cultures, perhaps even greater than the technology of production itself (1979: 70).  The difference between productive and reproductive technology is that the first is applied to increase production, the second applied to decrease reproduction.  Harris maintains that both are central in understanding modern industrial societies.

Both productive and reproductive technologies are attempts to regulate the flow and type of energy and raw materials from the environment.  Both technologies are included in Harris’s “infrastructure.”  They represent technologies and practices by which sociocultural systems adapt to their environments.  Because this activity is so crucial to the survival of individuals and sociocultural systems, Harris maintains, the adoption of these technologies will have tremendous impact on human institutions and cultural values and beliefs.  Harris fully explores the impact of productive and reproductive factors (including technology) on social institutions (such as the family, the workplace, etc.) and widespread ideals, ideologies and beliefs (the double standard, feminism, eating taboos). 

Malthus, a man of his times, failed to explore the implications of the new reproductive technologies.  Rather than examine the implications of these technologies for the future of population growth, Malthus simply asserts his belief that they would be harmful to marriage and family--and then examines them no more.  Malthus never developed either the logic or the empirical evidence to back up this claim.  In addition, he failed to detail how the introduction of these new reproductive technologies might affect the balance between positive and preventive checks.  This does not fulfill the modern social scientific ideal of value neutrality, of keeping your moral-political bias out of your analysis as much as possible.  And for this Malthus can be rightly criticized. 

But considering birth control technologies in the Malthusian system is not very difficult, nor does it significantly alter his basic theory.  Birth control has been added to the mix, but it has not changed fundamental relationships.  The cost-benefit decisions of couples are still determining factors.  Birth control does not control population--either people control it (sometimes using this technology), or nature does.  Regardless, the necessity and character of these checks have considerable effects on the rest of the sociocultural system.

Finally, both Harris and Malthus agree on the permanence of the population problem.  Let us suppose that the current population explosion is over.  A combination of economic development and education (thus leading to the preventive check of birth control), positive checks (high mortality), and totalitarian decree (as in modern day China) stabilizes the population on earth in the next century to the expected eleven billion--almost double our present population level.  With the stabilization of population levels we are still not out of the Malthusian woods.  Recall the Malthus’ theory is not one of a simple rise of population until it outstrips its environment.  Rather, it is a theory that centers on the relationships of population, production and the environment over time.  The need to continually balance our environmental resources, reproduction and production capabilities has grave consequences for the entire sociocultural system.  Because these consequences are those of sociocultural survival they necessarily affect all other parts of the sociocultural system.  And it must always be so.  Consistent with Malthus, Harris (1979: 282-283) points out that in the contest of man versus nature there can be no final victory.  The race is never over, any technological advantage can only be temporary.  Population must be continually checked and this basic fact is as true in today's hyper-industrial societies as it was in hunting and gathering societies. 

Harris' framework is capable of integrating a diverse range of theoretical insights and empirical observations within its scope.  In particular, Harris' concept of structure and superstructure can be further developed to incorporate more diverse sociological and anthropological theory (see Elwell, 1999).  But Malthus' insistence that relationships between population and production are at the base of all sociocultural systems, and that this base must necessarily have a profound effect on the rest of the system, are the core of all ecological-evolutionary theory. Our introductory texts should at least mention the main contributions of Malthus to social theory; our general theory texts should make this core explicit.

This essential core, it seems to me, allows a coherent world-view that can be used by social science practitioners and students to better interpret their world.  Like evolution in Biology, the ecological-evolutionary paradigm in the social sciences can provide the unifying themes and context for research and the interpretation of that observation.  It enables the social scientist to focus on problems of theoretical relevance so that the fields can systematically advance our understanding.  Facts can never speak for themselves, observation must be guided by some overarching vision.  If systematic observation were then to reveal that the paradigm is inadequate in its explanation, then modification of the paradigm to incorporate the new insight is necessary.  Should the new insight be resistant to integration with the reigning paradigm, then propose a new paradigm with greater explanatory powers.  This is the process by which the social sciences can truly advance our understanding of the social world. 

But the vast majority of the students in the social sciences today are not going to directly practice the craft.  It is in our interests, as well as in the interests of society as a whole, to teach our children a world-view that is consistent with both logic and observation, not continue to bombard them with facts, middle range theories, and partial explanations that only add to their confusion.  In accordance with Mills (1959), "The educational and political role of social science in a democracy is to help cultivate and sustain publics and individuals that are able to develop, to live with, and to act upon adequate definitions of personal and social realities" (p. 192).  If we fail to do this we all become far more susceptible to the ideological views of structural elites and other self-interested organizations. 

The existence of self-interest as a major factor in human motivation means that some inequality is built into the sociocultural system.  Because of the necessity of population checks, a sociocultural utopia based on science and technology, human reason, socialism, capitalism, or democracy is not part of the evolutionary process.  Nor is the current postindustrial dream of new technologies producing equality and plenty for all (Elwell, 1999).  Greater equality among all men and women, social justice, freedom and dignity will only result from the efforts of human beings to achieve these worthy goals--they will not evolve naturally (“progress” is not a product of either social or natural evolution). The inherent imbalance between our ability to have children and our ability to provide them with sustenance will always limit sociocultural systems, but this imbalance need not condemn us to a world without hope.

IV
There is an identifiable sociocultural evolutionary process. In this section I will summarize that process as identified by Marvin Harris (1979) and Lenski, Nolan, and Lenski (1995). Marvin Harris has been one of the strongest advocates of ecological- evolutionary theory in general, and cultural materialism in particular, for decades. Gerhard Lenski, almost alone among contemporary sociologists, has kept the ecological-evolutionary perspective alive in sociology. The two bodies of work have much in common. Both are strong advocates of the centrality of infrastructural environmental relationships in determining sociocultural evolution. Lenski (and his coauthors) tend to put more emphasis upon a society's social environment and on structural and superstructural feedback in general, but this is only a matter of emphasis, not really a difference in general theory (Harris's critics are simply incorrect when they assert that he reduces all society to mere reflections of infrastructure). The two perspectives are almost identical; both are in fundamental agreement with the following: 
 

1. There is no pre-established "direction" to the social evolutionary process. Societies evolve in response to changes in their natural environment or as the result of contact with other societies. 
2. Sociocultural systems evolve through the adaptations of individual behavior. "Just as a species does not 'struggle to survive' as a collective entity, but survives or not as a consequence of the adaptive changes of individual organisms, so too do sociocultural systems survive or not as a consequence of the adaptive changes in the thought and activities of individual men and women who respond opportunistically to cost-benefit options" (Harris, 1979: 61). 
3. Societies can be remarkably stable over time. Hunting and gathering societies existed with little technological, population, and structural change for thousands of years. Ancient civilizations that depended upon river irrigation as their mode of production were also remarkably stable. These stable societies can be characterized as successful attempts at striking a balance between reproduction and the consumption of energy from their finite environments. 
4. However, there is a bio-psychological cost in maintaining this balance for preindustrial people. Our ability to produce children has always been greater than our ability to produce food for their survival. In order to limit population size preindustrial societies have practiced infanticide and other forms of population control. 
5. The hold of tradition is particularly strong among preindustrial peoples. It has been a great conservative force throughout (up to now at least) social evolution. 
6. The modes of production of human societies have usually intensified (that is, over time they exhibit an increased use of technical knowledge, skills, and increased use of non-human forms of energy) because they must continually exploit less available, harder to reach sources of energy. For example, in a coal environment, we exploit the coal on the surface first. It is only after using up the readily available resources that we begin to dig deeper. Thus, a depleting environment causes the mode of production to intensify. 
7. Similarly, if "absolute" environmental depletion is reached and the society has accumulated the technical knowledge to shift to a new mode of production, the shift is a move from a readily accessible source (say, wood) to a less accessible source (coal, oil, or nuclear fission in its turn). Each succeeding energy source is more difficult to exploit. Each takes more general knowledge, capital, technology, and technical skill to tap. 
8. The intensification of the modes of production have also greatly increased productivity. While people must work harder to exploit each succeeding resource base, each new resource base represents a richer source of energy, allowing more food and other products to be produced. 
9. Because preindustrial people kept their population in balance with their environment mainly through infanticide, increased wealth is often used to support a greater number of children. In addition, children themselves can be used in preindustrial production, thus producing more wealth for their families. Each succeeding mode of production has therefore led to an increased size of the human population (thus putting further pressure on both the environment and on expanding the existing mode of production). 
10. With industrialization, the development of modern birth control techniques and changes in structure and superstructure, the relationship between the growth in the mode of production and population has been broken. 
11. Infrastructures of societies, that is a society's mode of production and its population, put very strong constraints on the range of widespread social institutions, ideas and ideologies of sociocultural systems. 
12. Structural elites and their interests provide positive and negative feedback to infrastructural change. This feedback can often be decisive in determining whether infrastructural change is amplified and propagated throughout the social system or whether it is extinguished. 
13. Cultural superstructures also provide positive and negative feedback for structural and infrastructural change. Superstructural feedback can be critical. If a sociocultural system exploits its environment to the point of "absolute" depletion (that is, the costs of necessary raw materials becomes prohibitive), and that system does not have the cultural knowledge base to switch to a new mode of production based upon a new resource base, that sociocultural system will collapse. 
14. Sociocultural adaptation and change is based on the alteration of existing structures and behavior patterns. The force of historical experience therefore plays a major role in shaping social institutions and thought. 
15. Unlike biological evolution, social evolution is a Lamarkian process, that is, successful adaptations can be learned. We do not depend on genetic variability and environmental selection for the preservation of successful adaptation. This is what makes social evolution so dynamic. 
16. Successful adaptations are spread through social contact, and military and economic conquest. While environmental necessity is the key to understanding "pristine" change-- that is change that is done in isolation from contact with other societies, the rapid adoption of most technologies and social practices are done through cultural diffusion. 
17. In addition to the general characteristics listed above, Lenski, Nolan and Lenski (1995) take social evolution a step further and posit a process of selection in the world system that favors larger, more powerful societies at the expense of smaller, less powerful ones. There has been a dramatic reduction in the number of societies in the world system in the last 10,000 years due to a process of intersocietal selection. Societies that have grown in size and technology have also grown in complexity and military power; this has allowed them to prevail in conflict over territory and other resources with societies that have maintained more traditional sociocultural patterns. 

From Max Weber: 

The perspective of sociocultural materialism presented in these essays represents a synthesis of ecological- evolutionary theory with the sociology and insights of Max Weber. With his typology of human action and his theory of increasing rationalization, Weber characterized the sweep of human history. While Weber's is an evolutionary theory, he did not root his theory of increasing rationalization and the growth of bureaucracy in ecology. Doing so, however, is not a difficult task: 
 

Modes of production limit widespread social structures (that is, family, economic, government) and superstructures (ideas, ideologies, and even entire cultural world views).  Structures and superstructural ideas have influence on infrastructural intensification.

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