Until the mid-nineteenth century, the worldwide archaeological sequence remained extremely unclear, and until the advent of radiometric dating in the midtwentieth century the length of the sequence was consistently underestimated. This did not prevent Europeans of the sixteenth and seventeenth century, in contact with less politically complex societies in the Americas and Africa, from using these societies as models for ancient societies around the world. Evolutionary concepts were much ‘in the air’ by the early 1800s, and in the 1850s, Herbert Spencer applied evolutionary ideas to what he believed to be the sequence of development of human societies around the world. For Spencer, evolution was a universal concept applicable to the development of complexity in the physical, biological, and social realms; as he used it in regard to society, it seems to have been synonymous with progress.
Such study of ‘cultural evolution’ was the first systematic manifestation of evolutionary interests in anthropology and archaeology. Workers in this tradition focused on identifying and describing what were thought to be successive and, usually, universal stages of increasingly complex technologies, economies, and sociopolitical structures. At the same time they devoted comparatively less attention to the processes that might have caused societies to move from one of these stages to the next.
The American lawyer Lewis Henry Morgan, for example, identified three major stages (savagery, barbarism, and civilization), with additional substages, through which he believed societies passed in sequential fashion. Technological innovations were important in differentiating these stages, although Morgan considered societies to be functionally integrated, so changes in technology could influence other aspects of society, and vice versa. In formulating his taxonomy, Morgan took into account the findings of contemporary ethnology and archaeology (a field just then beginning to find its feet). Morgan’s work in turn influenced Marx and Engels (see Marxist Archaeology).
There were isolated attempts to apply the principles of evolution directly to the study of artifacts. In the 1860s and 1870s, Lieutenant General A. Lane-Fox Pitt-Rivers gave a series of lectures, collected in 1906, in which he endeavored to place in order of sequential development many different kinds of artifacts, including boomerangs and stone tools (Figure 1). The principles used to obtain his sequences are still worth reading, and included the idea that artifacts change from the simple to complex by means of the accumulation of many very small changes - not all of which are accepted - and also the concept that parts could be dissociated from complex artifacts to form new artifacts. Diagrams such as that in Figure 1 foreshadow seriations by cultural-historical archaeologists in the first half of the twentieth century, and cladistic (or phylogenetic) approaches that began in the late twentieth century.