The Pleistocene prehistory of the Lake Victoria basin

Abstract

of increased aridity repeatedly facilitated the dispersal of C 4 grassland ecosystems across the basin. Archaeological evidence from Middle Stone Age and Later Stone Age sites suggest that human groups diffused into the basin during intervals of declining lake levels, likely tracking the movement of the dense and predictable resources of shoreline environments as well as the dense but less predictable C 4 grass grazing herbivores. Repeated cycles of lake expansion and contraction provide a push-pull mechanism for the isolation and combination of populations in Equatorial Africa that may contribute to observed Late Pleistocene human biological variability suggested by the fossil and genetic records. Latitudinal differences in the timing of environmental change between the Lake Victoria basin and surrounding regions may have promoted movements across, within, and possibly out of Africa.

Reconstruction of Late Pleistocene Paleoenvironments Using Bulk Geochemistry of Paleosols from the Lake Victoria Region

“…These reconstructions of the upper and lower paleo-CZ using paleosol features, grain size, and bulk geochemical proxies for MAP also agree with vegetation reconstructions using pedogenic carbonates, soil organic matter, and tooth enamel from Rusinga and Mfangano Islands, which indicate the local occurrence of a woodland to grassy woodland surrounded by an expansive C 4 grassland Garrett et al, 2015;Tryon et al, 2016). The fossils from this region are dominated by a diverse population of grazing herbivores and arid-adapted ungulates such as oryx (Oryx beisa) and Grevy's zebra (Equus grevyi), which are found far outside their modern range of arid eastern and northeastern Africa .…”

“…These sites sample an approximately 55 km-long north to south transect along the eastern margin of the modern lake: Rusinga Island (n = 2), Mfangano Island (n = 1), and Karungu (n = 4) (Figure 1; Tryon et al, 2014Tryon et al, , 2016Beverly et al, 2015a,b;Blegen et al, 2015;Faith et al, 2015;Garrett et al, 2015). These deposits are all part a sequence of late Pleistocene deposits around the northeastern margin of Lake Victoria and the stratigraphy is dominated by paleosols, freshwater tufa, fluvial deposits, and volcaniclastic deposits (tuffs) that can be geochemically correlated between outcrops (Tryon et al, 2010Van Plantinga, 2011;Beverly et al, 2015a,b;Blegen et al, 2015Blegen et al, , 2016Faith et al, 2015).…”

The Middle/Later Stone Age transition and cultural dynamics of late Pleistocene East Africa

“…For example, from ~36 to 94 ka and 14 to 17 ka, at least Lake Victoria, the dominant water feature of the region, had either dried up completely or was substantially reduced in size, changing what is now a lake habitat to an extensive Serengeti‐like grassland dominated by extinct and often strikingly distinctive animal communities (Figure ) . The rainforest is also subject to extensive contraction, fragmentation, or expansion caused by increases or decreases in rainfall that may have contributed to intermittent hominin occupation of its margins . Nearshore islands such as Zanzibar appear to have been occupied as early as the LGM ~18–26 ka, possibly aided by lowered sea level .…”

“…East Africa is a useful region to study because of its relatively large number of archeological sequences that sample the MSA/LSA transition, including Enkapune ya Muto, Kisese II, multiple sites at Lukenya Hill, Magosi, Magubike, Mtongwe, Mumba, Nasera, Panga ya Saidi, and Shurmai; individual MSA and LSA sites in the Lake Victoria basin, Olduvai Gorge, and Kuumbi Cave provide additional constraints on the transition but lack extensive stratigraphic sequences or large sample sizes sufficient to assess change over time (Table ). East Africa as defined here encompasses ~1.77 million km 2 and can serve as a useful point of comparison for other similarly sized regions that also preserve MSA/LSA sequences, such as Ethiopia and the Horn of Africa (~1.88 million km 2 ), as well as southern Africa (~2.09 million km 2 ) …”

Excavations at Mlambalasi Rockshelter: a Terminal Pleistocene to Recent Iron Age Record in Southern Tanzania

“…During the final stages of the Pleistocene, many African great lakes experienced significant water-level drops with related impacts on vegetation cover (Gasse 2000;Barker and Gasse 2003;Gasse et al 2008;Vincens et al 2005). Lake Victoria evaporated completely between c. 17,000-16,000 BP and again c. 15,000-14,000 BP, with a demonstrable Bpush-pull^effect on human and animal populations (Johnson et al 1996;Tryon et al 2015;Verheyen et al 2003). Although we lack fine-grained palaeoclimatic data for many subregions (Grine 2016), the absence of archaeological sites in many parts of the continent during glacial maxima suggests that many regions could not sustain human life (Willoughby 2012).…”