Isotope Assessment and the Seasonal-Mobility Hypothesis in the Southwestern Cape of South Africa [and Comments and Replies]

Abstract

This paper consists of a stable carbon isotopic assessment of the diets of the Holocene human inhabitants of the southwestern Cape, South Africa. Samples of the foods these people ate were collected from each of the four major physiographic zones in the area and their 13C/12C rations measured. A total of more than 200 such analyses enabled the estimation of the average 13C values of prehistoric human diets in each zone. This information is used to interpret 13C measurements on a series of archaeological human skeletons. The results are consistent with a model of prehistoric subsistence behaviour in which a number of people living at the coast made intensive use of marine food resources throughout the Holocene, consuming such a large proportion of these foods that they must have spent much if not all of their time at the coast. Most inland skeletons reflect an almost entirely terrestrial diet. These results contradict hypotheses about seasonal population movements between the coast and the interior generated from excavated archaeological material. Considerable changes in many of our current views of the Late Stone Age of the southwestern Cape will have to be made in order to accommodate these data.