The "golden age" of social evolutionism had basically ended by the 1890s, and after that time a sharp reaction against evolutionary theories emerged. In anthropology this reaction was led by Franz Boas and his students and disciples and lasted into the 1940s and 1950s. The Boasian school objected to evolutionary theories on four basic counts: the use of an illegitimate methodological device, the Comparative Method; the development of rigid schemes of unilinear evolution in which all societies were assumed to progress in lockstep fashion through the same set of stages; inadequate recognition of the process of diffusion; and the illegitimate equation of evolution with progress (see Sanderson 1990). Nonetheless, by the 1930s the extreme historical particularism espoused by the Boasian school of anthropology began to be challenged, and an "evolutionary revival" was underway.
The first to lead this revival was the archaeologist V. Gordon Childe (1936, 1951). Emphasizing the broad technological changes characteristic of human prehistory, Childe identified two great technological revolutions that had occurred in several regions of the world. The Neolithic Revolution brought about the domestication of plants and animals. It gave humans the possibility of accumulating economic surpluses, and thus paved the way for the second revolution, which Childe called the "urban revolution." This involved the passage of human societies into a much more complex form characterized by occupational specialization, cities, sharp class divisions, and the state. Beginning in the 1940s, Leslie White (1943, 1959a) developed a version of social evolutionism similar to Childe's. White insisted that evolutionary theories did not try to explain specific sequences of historical change, but rather focused on the overall movement of human culture as a whole. He formulated a law to explain this general evolution of culture, which stated that culture evolved in proportion to the amount of energy harnessed per capita per year, or by an increase in the efficiency of putting this energy to work. In other words, technological change is the driving force of the evolution of culture. Julian Steward, the third important figure in the evolutionary revival, reacted against what he thought were the overly general and excessively simplified evolutionary conceptions of Childe and White, which he called "universal evolution." He proposed instead what he termed "multilinear evolution" (Steward 1955). Multilinear evolution concentrated less on the overall movement of history and more on the different lines along which social evolution moved. Steward granted that there were broad parallels in historical change, but he did not want these overstated. There were still many different lines along which evolution radiated, and these could not be ignored.
Since about 1960, there has been a new wave of important evolutionary work among American anthropologists, most of whom have been greatly influenced by the evolutionism of Childe and White. Marshall Sahlins (1958) wrote an important book on the evolution of social stratification that was inspired by the technological emphasis of Childe and White. He also contributed an important article (Sahlins 1960) that distinguished between general and specific evolution, the former being the overall movement of historical development, the latter the more specific radiation of culture and society along many lines. Elman Service (1962/71) and Robert Carneiro (1970) have also made important contributions to the study of political evolution. Service advanced the typology of "band tribe chiefdom state" to characterize political evolution, a typology that has been widely employed in ethnographic and archaeological research. The evolution from one stage to another is a movement to more hierarchical and complexly integrated political systems. Service's theory is a kind of functionalist one in which new political forms are said to evolve because of their greater functional effectiveness. Carneiro, by contrast, presented a conflict theory to account for the evolution of chiefdoms and states. He saw population pressure and warfare as contributing to the development of more complex political systems in areas that are environmentally circumscribed. As population pressure and warfare increase, people have nowhere to go and ultimately become conquered and subordinated by other groups. As a result, political systems grow increasingly powerful and complex. Gerhard Lenski (1970), a sociologist by training, worked out a well-known theory of social evolution that was largely an extension and elaboration of the ideas of Childe and White. Lenski saw technological expansion as the prime mover of social evolution. As technology expands, economies become more productive and economic surpluses emerge and expand. These technoeconomic changes ramify throughout social life and lead to major evolutionary transformations. One of Lenski's most important applications of this theory was to the evolution of social stratification.
Marvin Harris (1977, 1979) has presented a quite different conception of social evolution. Rather than viewing technology as evolution's driving force, he sees most people throughout history resisting technological change because of the greater costs in human time and energy it requires. What drives social evolution is the tendency of humans to suffer eventual depletions in their standard of living as the result of population pressure and environmental degradation. People must then work harder and longer and eventually advance their technology that is, they must intensify their production just to keep their standard of living from falling even lower. But these changes produce yet further (and even greater) depletions, and so the depletion intensification depletion process spirals ever forward and upward.
The current situation is a mixed one. In recent years there has been a substantial reaction against general theories of historical change, and many scholars now assume it is only possible to do limited kinds of theorizing about specific historical situations and trajectories. All of this has meant a sharp decline in confidence in any type of evolutionary theory. Indeed, some social scientists have been severely critical of evolutionism (see Sanderson 1990: ch. 9). Nonetheless, many social scientists remain committed to evolutionary analyses and extensive research on social evolution continues. This is especially true in anthropology and its subfield of archaeology. Archaeology has long been evolutionary, and, although some archaeologists have turned against evolutionism, most probably remain within that camp.
Steward's materialist orientation likely stems from a combination of factors, including his preparatory school experience, undergraduate studies, early fieldwork in the 1930s in archaeology in the harsh environments of the southwest and Great Basin and Plateau, ethnographic field experience with the Shoshoni (whose culture appears to have focused on survival), and the Dust Bowl and the Great Depression. Through his fieldwork he cultivated cultural ecology which eventually became a means to the end of his theory of multilinear evolution (Steward 1938). Ultimately Steward was always interested in the scientific and materialist explanation of culture, including causality; that is, discovering laws of regularities in the patterns, functions, and processes of cultural diversity. This penchant for theorizing and generalizing also set Steward apart from the Boasians. In short, Steward was a rebel, an inclination that actually started in his youth, when he turned away from the Christian Science religion of his parents to pursue instead natural causes through scientific explanations.
These considerations help explain why Steward became the single most important anthropologist in the development of cultural ecology from the 1930s into the 1960s. In his field research, publications, and teaching, Steward persistently developed a theoretical and methodological framework for studying Cultural Change as adaptation in which environmental influences were especially important. Unfortunately, Steward did not develop his theory and method in a single, readily accessible publication. Rather, his theory and method have to be extracted from numerous sources, including two edited books of diverse essays (Steward 1955, 1977).
It is important to clearly distinguish two different levels at which Steward operated the ethnographic sphere, in which a particular culture was described through intensive fieldwork in the Boasian tradition, and the ethnological sphere, in which a small number of cultures were compared for the purposes of generalization and explanation. Cultural ecology has continued to strongly influence anthropological research on human environment interactions, while multilinear evolution has been pursued to a much lesser extent (Carneiro 1990; Kirch 1984). However, Steward is seldom adequately acknowledged by researchers studying cultural ecology or multilinear evolution.
Rather than arguing on the basis of available literature that either the environment rigidly determines culture (environmental determinism) or the environment allows some degree of latitude for alternative cultural responses (environmental possibilism), Steward avoided prejudgement and advocacy, allowing for influences in either direction (environment to culture and culture to environment). He subjected this relationship to direct empirical investigation through fieldwork on particular cultures in their habitat. Through ethnographic fieldwork with the Shoshoni and Paiute, Steward (1955) specified three successive but interrelated steps in the investigation of the cultural ecology of a particular society: (1) the natural resources and the technology used to extract and process them; (2) the social organization of work for these subsistence and economic activities; and (3) the influence of these two phenomena on other aspects of culture, including social, political, and religious institutions. In this manner Steward developed an ecological framework for describing and to some degree explaining a particular culture. This framework focused on the specific behavior involved in the technology and work of extracting natural resources for survival. Thus Steward's approach has proven most applicable to societies with economies focused on subsistence; that is, foragers or hunter gatherers, Swidden horticulturalists, fishers, and pastoral nomads.
Steward, however, was not satisfied with this particular level of research. Ultimately he was more interested in the comparative level in order to discover the underlying causes and laws of cultural phenomena. He was especially concerned with employing empirical data from research in cultural ecology to compare a small sample of cultures in order to formulate generalizations about limited parallels in patterns, functions, and processes. He called this "multilinear evolution," as distinct from the unilinear evolution of Edward Tylor and Lewis Henry Morgan in the late nineteenth century, or the universal evolution of his contemporary Leslie White (Carneiro 1973). Steward's methodological approach to multilinear evolution was to select for detailed comparison a small number of particular cultures that were in similar environments (e.g., types of desert or forest) and at the same level of sociocultural integration (Family, Band, Tribe, Chiefdom, Or State), but widely separated geographically. The great spatial distance between the cultures chosen for the sample was supposed to eliminate the possibility of cultural similarities arising from Diffusion, thus controlling for the historical factor that had been so prominent in the anthropology of the Boasians. Accordingly, similarities in the sample of cultures that Steward selected would have to be the result of parallel adaptations, that is, similar responses to similar environmental conditions. In this way Steward attempted to go beyond ethnographic description to the scientific and materialist explanation of cultural similarities and differences (Sponsel 1987).
The principal criticisms of Steward's approach are that his theoretical concepts were not very clear and useful; that his method was mostly intuitive; that he was a functionalist; and that he focused rather narrowly on subsistence economy to the neglect of many other important factors, such as population dynamics, natural hazards, political institutions, and religion (see J. Anderson 1973; Orlove 1980; Vayda & Rappaport 1968). However, assessed in historical context, Steward's contributions were and remain significant.
White's support of evolutionary theory was not well received until near the end of his career, in part because he took aim at Boas and his followers in a polemical style that took no prisoners. His position, stated most completely in The evolution of culture (1959a), was strongly materialist and became best known for its assertion that use of energy per capita was the best way to measure social complexity and rank societies in an evolutionary scheme. Although Julian Steward (whom White had replaced at Michigan) argued along similar lines, White rejected his model as not general enough and too focused on the environment (Carniero 1973).
The environmental objection may seem strange for a materialist, but White's other passion was promoting what he called "culturology," the idea that Culture was defined only by human manipulation of symbols and formed an autonomous class of phenomena that could be studied as a science. Similar to Kroeber's (1917a) "superorganic," culture was something real that existed outside the individual, independent of psychology, biology, or the environment. Expressed at length in The science of culture (1949), White's theory suggested that there could be laws of culture.
White saw energy or, more accurately the model of harnessing it and putting it to human use, as the key component in how societies evolved and changed. Moving from food gathering to food production, then on to the use of fossil fuels, culture was transformed – evolved – from primitive to modern. Culture was made possible by the ability to symbol, but for White material inventions were the most important product of such symboling. His famous formula stated: “As the amount of energy harnessed per capita per year increases, culture will advance.” In White’ scheme of things technology was the key driver of Culture and specific cultures. That is while he believed that culture developed generally toward states of higher complexity and greater harnessing of energy, he acknowledged that individual cultures developed in response to a variety of particular factors. His interest was in all human culture rather than in particular cultures. Initially the human species had lived in small societies that depended on hunting and gathering to survive, using their own energy, augmented by tools. In time, humans learned to farm, planting culgens and using the energy of domesticated animals. This led to larger communities and more complex societies, some of which used water power in irrigation and milling, as well as wind power. Then ccame of modern civilization White was writing as nuclear energy was increasingly heralded as the energy source of the future, and he believed that we were entering a new era that would lead to still more complexity.
Many found White's position contradictory: how could a materialist give primacy to cultural determinism when his own evolutionary model had focused on such noncultural criteria as energy use? Nor were students of symbolic anthropology likely to believe that they were producing a set of scientific laws.
The specifics of White's theories have ultimately proved less influential than his support of the principle of evolution. White insisted on its value over many decades when such models were looked upon with distaste or derision. His writings and his students laid the groundwork for evolution's reemergence into the mainstream of anthropology beginning in the 1960s, although few adopted his specific models. By the end of his career White had received numerous awards, including his election as President of the American Anthropological Association in 1964. After retiring from Michigan in 1970, he moved to the University of California at Santa Barbara, where he died in 1975.