Scientific Dating Methods in African Archaeology

Abstract

The African archaeological record is particularly remarkable in that it covers timescales relevant to all human history and prehistory. Different dating techniques are therefore fundamental to constructing reliable chronologies for the continent. The principal factors that determine the usefulness of a dating technique are (1) applicability to the material in question, (2) the expected precision of the technique, and (3) the age range over which it is expected to be useful. Radiocarbon is applicable to the past fifty thousand years of human history, encompassing the Later Stone Age, Iron Age, and historical periods, and is a highly-refined method applicable to organic materials such as bones, plant matter, charcoal, teeth, and sometimes eggshell. However, African archaeological contexts often present challenges to the preservation of material, and it is important to establish the context of the material under investigation. Materials of preference for radiocarbon dating, such as plant cellulose, are thought to be resistant to alteration during burial (diagenesis). The age ranges of luminescence and uranium-series dating stretch well into the African Middle Stone Age. Luminescence dating is applied to sediments and burnt objects, and uranium-series (U-series) dating is applied to geological materials such as carbonates and stalagmites. In some special cases, U-series dating can also be applied to fossil bones, teeth, and eggshell. For all dating methods the importance of context cannot be overstated. Other techniques, such as archaeomagnetic dating and rehydroxylation (RHX) dating, should be applicable over the historical period, but these new methods are under development. Dating methods are an active area of interdisciplinary research, continuously refined and developed, and collaboration between African archaeologists, geologists, and dating specialists is important to establish accurate regional chronologies.