Sharon E. Nicholson
Environmental constraints have large impacts on populations, especially in semi-arid regions such as Africa. Climate and weather have long affected African societies, but unfortunately the traditional climatic record for the continent is relatively short. For that reason, historical information has often been used to reconstruct climate of the past. Sources of historical information include reports and diaries of explorers, settlers, and missionaries; government records; reports of scientific expeditions; and historical geographical and meteorological journals. Local oral tradition is also useful. It is reported in the form of historical chronicles compiled centuries later. References to famine and drought, economic conditions, floods, agriculture, weather events, and the season cycle are examples of useful types of information. Some of the records also include meteorological measurements. More recently chemical and biological information, generally derived from lake cores, has been applied to historical climate reconstruction. Early works provided in most cases qualitative, discontinuous information, such as drought chronologies. However, a statistical method of climate reconstruction applied to a vast collection of historical information and meteorological data allowed for the creation of a two-century, semi-quantitative “precipitation” data set. It consists of annual indices related to rainfall since 1800 for ninety regions of the African continent. This data set has served to illustrate several 19th-century periods of anomalous rainfall conditions that affected nearly the entire continent. An example is widespread aridity during several decades early in that century.
While there are a handful of defined methods for working with primary historical sources in archaeology, few archaeologists take these as their main points of departure or rely upon them too rigidly. This is to do both with the highly variable nature of the historical and archaeological material available for certain African contexts, and also with how archaeologists conceive of the relationship between these two bodies of evidence: as antagonistic, supplementary, entangled and subjective, mutually creative, and so on. Some methodologies focus on the potentials for consonance and dissonance between written and material sources. Others utilize oral traditions to provide insights into chronology, memory, historical and political dynamics, and the material aspects of these. Still other approaches focus on how historical and archaeological sources offer complementary perspectives on the local and the global, events and processes, and other shifts in scale. While these methods are diverse and contingent, they are united insofar as archaeologists take their cues from objects and from preoccupations with time and space. Archaeologists see their work concerning primary historical sources not as filling in gaps in written records but as addressing the partialities of the records themselves by engaging with an array of complex questions about meaning, authority, and materiality