Late Cenozoic Moisture History of East Africa

Abstract

Lake sediments in 10 Ethiopian, Kenyan, and Tanzanian rift basins suggest that there were three humid periods at 2.7 to 2.5 million years ago (Ma), 1.9 to 1.7 Ma, and 1.1 to 0.9 Ma, superimposed on the longer-term aridification of East Africa. These humid periods correlate with increased aridity in northwest and northeast Africa and with substantial global climate transitions. These episodes could have had important impacts on the speciation and dispersal of mammals and hominins, because a number of key events, such as the origin of the genus Homo and the evolution of the species Homo erectus, took place in this region during that time.

Cytochrome b sequence analysis reveals differential molecular evolution in African mole-rats of the chromosomally hyperdiverse genus Fukomys (Bathyergidae, Rodentia) from the Zambezian region

“…The chronogram (Fig. 7) reveals that the observed cladogenetic events during the Plio-Pleistocene within the F. mechowii, F. whytei, F. damarensis and F. micklemi clades appear to coincide with climatically mediated speciation bursts in other savannah dwelling mammals, including hominids (Ducroz et al, 1998;Bobe and Behrensmeyer, 2004;Trauth et al, 2005;Veyrunes et al, 2005).…”

Stable isotopes of pedogenic carbonates as indicators of paleoecology in the Plio-Pleistocene (upper Bed I), western margin of the Olduvai Basin, Tanzania

“…There is a growing body of literature suggesting wet/dry cycles occur in the East African Rift in concert with astronomically driven (Milankovitch) glacial-interglacial obliquity cycles (~ 41,000 yrs) in addition to precession cycles (19,000-23,000 yrs; Pokras and Mix, 1987;Gasse et al, 1989;Ruddiman et al, 1989;Imbrie et al, 1993;deMenocal and Bloemendal, 1995;Trauth et al, 2005;Deino et al, 2006). Alhough the continental record is discontinuous and cannot be expected to mirror the marine sedimentary sequence (see Sikes, 1999), stable isotopic studies of paleosols have been correlated with other continental or global proxy records of paleoclimate (Smith et al, 1993;deMenocal, 1995;Quade et al, 1995).…”

Ecological consequences of early Late Pleistocene megadroughts in tropical Africa

“…For Africa, understanding of Pleistocene environmental history comes from a variety of wetland, lake core, and outcrop records (3)(4)(5)(6)(7), which are of geologically short duration and/or low stratigraphic resolution, as well as from analyses of deep-sea cores (8,9), which integrate information from large areas. To evaluate hypotheses about environmental history at the landscape scale (Ϸ10 4 -10 6 km 2 ), and their potential influence on species' distribution and diversification histories (10), there is a need for records that merge the continuity and duration of deep-sea cores with the relatively rapid sedimentation and high temporal resolution found in lakes.…”