Book excerpt: The hunting and gathering way of life is the most enduring and resilient in human history. However, the ways that a wild food-based subsistence system affects people's social and economic organization are often oversimplified and variability is poorly understood. In general, there's been a tendency, particularly among non-Anthropologists, to assume that hunter-gatherer societies are static and that historic groups represent an earlier, simpler way of life. This is particularly true in Africa, where small, highly mobile groups are common ethnographically. However, dramatic rainfall fluctuations over the last ~30,000 years significantly altered resources available to hunter-gatherers in diverse environments of northern and eastern Africa. To examine the ways hunter-gatherer groups responded to terminal Pleistocene and Holocene climatic shifts and investigate social and economic variability through time, this thesis compares two long archaeological sequences from distinct eastern African ecozones in semi-arid versus humid settings. Radiocarbon dates and faunal data from the Guli Waabayo rock shelter in the semi-arid plains of the southern Horn of Africa revealed occupation between ~26-6 kya. New dates indicated that early use of the site occurred during a period of aridity in the last glaciation, but Holocene occupation was associated with higher rainfall. Faunal species representation demonstrates that, throughout these fluctuations, people maintained a remarkably consistent focus on small game. Taxonomic and age based evidence for specialized dik-dik net-hunting during both arid and humid periods indicates maintenance of unique and resilient hunter-gatherer social and economic strategies that allowed people to survive on the Buur Heybe inselberg for thousands of years. In comparison, excavations at the Namundiri A shell midden in Uganda provide new insights into the flexibility of complex Kansyore hunter-gatherers who occupied the well-watered Lake Victoria Basin of East Africa ~8. 5-1. 5 kya. Dates from the site are the first evidence of Kansyore occupation between ~7-4. 4 kya, which, combined with site location and faunal data, indicate relatively stable lifeways along the lakeshore leading up to an arid phase in the mid-Holocene ~5-4 kya. Abandonment of the lake's edge and an increased emphasis on fishing along inland rivers after this period suggests reorganization among hunter-gatherers in response to changing climatic and environmental conditions in order to maintain a consistent presence in the region. This examination of Late Quaternary and Holocene hunter-gatherers living in drier and wetter regions of eastern Africa draws attention to the different ways foraging groups responded to environmental and social shifts in order to maintain continuity over long time spans. Together, these two case studies highlight unique hunter-gatherer strategies that involved reduced mobility and subsistence specialization, which are not documented in the ethnographic record of Africa. As a result, this research helps to expand global understandings of variability in the hunting and gathering lifestyle.