The Last Glacial Maximum and Acceleration of Technological Change in the Lesotho Highlands

Abstract

Between 45,000 and 25,000 years ago, the prepared cores and formally retouched tools of the southern African Middle Stone Age were replaced by idiosyncratic, informal, and miniaturized lithic assemblages. This murky period of prehistory, loosely named the “Middle to Later Stone Age Transition” (MSA/LSA transition), terminated with the appearance of southern Africa’s first true Later Stone Age (LSA) industry, the Robberg, and the onset of the Last Glacial Maximum (LGM). The LGM profoundly impacted southern Africa’s human occupants by altering the livability of certain environments and the distribution of bioavailable resources. Despite this, the relationships between the MSA/LSA transition, the beginning of the Robberg, and the onset of the LGM are relatively misunderstood. Previous studies have emphasized the differences between final Middle Stone Age (MSA), transitional, and Robberg industries, attributing the slow spread of the poorly defined “Early Later Stone Age” (ELSA) technocomplex to diffusion or migration from other parts of the subcontinent and denying the roots of Robberg technology in the MSA (C. B. Bousman & Brink, 2018; Goodwin & Van Riet Lowe, 1929). This dissertation tests three hypotheses on the MSA/LSA transition through the analysis of lithic assemblages from Melikane Rockshelter, Lesotho: that the transition was precipitated by population replacement, that it was a consequence of changes in mobility and resource distribution due to LGM conditions, and/or that it was prompted by demographic shifts unrelated to large-scale migration. Melikane, a large sandstone rockshelter in the Maloti-Drakensberg Mountains of highland Lesotho, preserves an 80,000-year-old archaeological sequence including two layers (4 and 5) dated to the onset of the LGM (~24,000 years ago) and previously assigned to the MSA/LSA transition. For this dissertation, I analyzed > 17,000 lithic artifacts from layers 4 and 5 to understand how the MSA/LSA transition at Melikane was related to either external or local mechanisms of change. Although there are some similarities between the lithics at Melikane and other penecontemporary sites, I conclude that there is no evidence to support the hypothesis that the MSA/LSA transition was a population replacement or migration event. In contrast, layer 5’s heavily reduced microlithic assemblage suggests that Melikane’s early LGM foragers were isolated from lowland and interior populations. The microlithic roots of Robberg technology were already established in layer 5 and became entrenched as new challenges to mobility and resource scheduling favored the use of standardized bladelet technologies. However, the introduction of a new core reduction sequence in layer 4 insinuates that some, but not all, Robberg technologies were introduced from outside the highlands. This implies that population connectivity was reestablished in southern Africa following an earlier period of isolation, potentially as changing environmental conditions provided an impetus for movement. This cycle of isolation and connectivity would encourage the development of regionally adapted technological systems while simultaneously allowing for the spread of new elements, potentially leading to the Robberg’s fluorescence following the LGM. Overall, my findings support an indirect role for environmental change in the MSA/LSA transition. Microlithic LSA technologies were rooted in the Middle Stone Age, fully adopted only when the right environmental and demographic conditions were met.