Ungulate community richness, grazer extinctions, and human subsistence behavior in southern Africa's Cape Floral Region

Abstract

Precipitation, primary productivity, and herbivore biomass are linked to ungulate richness (the number of species) in African ecosystems. This study compares the richness of late-middle to late Pleistocene and Holocene ungulate assemblages in southern Africa's Cape Floral Region (CFR). Regression analysis demonstrates that Pleistocene ungulate assemblages are significantly richer than their Holocene counterparts. Elevated Pleistocene ungulate richness is not explained by differential time-averaging, the presence of extinct taxa in Pleistocene assemblages, or by Middle Stone Age (MSA) to Later Stone Age (LSA) technological change, but instead by a greater number of grazing species in Pleistocene faunal communities. Based on modern African analogs, this implies that the Pleistocene assemblages examined here sample time intervals characterized by elevated primary productivity, particularly of grassland habitats, greater ungulate biomass, and altered rainfall regimes. Declining ungulate richness from the Pleistocene to the Holocene supports the hypothesis that the extinction of specialized grazers at the Pleistocene–Holocene transition in the CFR was driven by declining productivity and availability of grassland habitats. The contrast between rich Pleistocene ungulate communities and impoverished Holocene ungulate communities may also explain important differences in MSA and LSA subsistence behavior. It is proposed that intensified exploitation of fish, shellfish, tortoises, and seabirds by LSA foragers during the Holocene reflects an expansion of diet breadth in response to diminished ungulate biomass on the landscape rather than fundamental behavioral/cognitive advances.