Heritage Cases

In historic times the coast of South Africa, due to its peculiar floral ecosystem, has few large mammals and none of the migratory species so typical of the rest of Africa. Yet, in the archaeological sites on the coast, the bones of large migratory species are common (Klein 1983). Underlying the sea in this region is a shallow gradually descending shelf that, during periods of lowered sea level, would be exposed. Our 3D computer model of this underwater feature shows that during the glacial maximum the coastline was 95 km distant (Fisher et al. 2010). Because summer rains dominate the land to the east, and winter rains to the west, we hypothesize that a seasonal migration of large mammals existed on this once exposed plain, and that early modern humans hunted them from the caves, providing them with valuable foraging returns during harsh glacial cycles (Marean 2010). If this is true, genetics of the fossil animal bones should show a pattern where the population size of the migratory species expands during glacials and contracts during inter-glacials. We propose to extract the ancient DNA from the bones of these ancient animals and directly test this hypothesis. An ancillary benefit of this study will be that it will be the first to use ancient DNA of fossil animals to address questions of climate and environmental change in Africa, and thus open a new research direction.