Ecological consequences of early Late Pleistocene megadroughts in tropical Africa.
Andrew S. Cohen,Jeffery R. Stone,Kristina R.M. Beuning,Lisa E. Park,Peter N. Reinthal,David L. Dettman,Christopher A. Scholz,Thomas C. Johnson,John W. King,Michael R. Talbot,Erik T. Brown,Sarah J. Ivory +11 more
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This record of lake levels and changing limnological conditions provides a framework for interpreting the evolution of the Lake Malawi fish and invertebrate species flocks and places new constraints on models of Afrotropical biogeographic refugia and early modern human population expansion into and out of tropical Africa.Abstract:
Extremely arid conditions in tropical Africa occurred in several discrete episodes between 135 and 90 ka, as demonstrated by lake core and seismic records from multiple basins [Scholz CA, Johnson TC, Cohen AS, King JW, Peck J, Overpeck JT, Talbot MR, Brown ET, Kalindekafe L, Amoako PYO, et al. (2007) Proc Natl Acad Sci USA 104:16416–16421]. This resulted in extraordinarily low lake levels, even in Africa's deepest lakes. On the basis of well dated paleoecological records from Lake Malawi, which reflect both local and regional conditions, we show that this aridity had severe consequences for terrestrial and aquatic ecosystems. During the most arid phase, there was extremely low pollen production and limited charred-particle deposition, indicating insufficient vegetation to maintain substantial fires, and the Lake Malawi watershed experienced cool, semidesert conditions (<400 mm/yr precipitation). Fossil and sedimentological data show that Lake Malawi itself, currently 706 m deep, was reduced to an ≈125 m deep saline, alkaline, well mixed lake. This episode of aridity was far more extreme than any experienced in the Afrotropics during the Last Glacial Maximum (≈35–15 ka). Aridity diminished after 95 ka, lake levels rose erratically, and salinity/alkalinity declined, reaching near-modern conditions after 60 ka. This record of lake levels and changing limnological conditions provides a framework for interpreting the evolution of the Lake Malawi fish and invertebrate species flocks. Moreover, this record, coupled with other regional records of early Late Pleistocene aridity, places new constraints on models of Afrotropical biogeographic refugia and early modern human population expansion into and out of tropical Africa.read more
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Ancient hybridization fuels rapid cichlid fish adaptive radiations.
Joana I. Meier,David Alexander Marques,David Alexander Marques,Salome Mwaiko,Salome Mwaiko,Catherine E. Wagner,Catherine E. Wagner,Catherine E. Wagner,Laurent Excoffier,Ole Seehausen,Ole Seehausen +10 more
TL;DR: It is demonstrated that hybridization between two divergent lineages facilitated this process by providing genetic variation that subsequently became recombined and sorted into many new species, indicating rapid and extensive adaptive radiation.
Journal ArticleDOI
The dawn of human matrilineal diversity.
Doron M. Behar,Richard Villems,Himla Soodyall,Jason Blue-Smith,Luísa Pereira,Ene Metspalu,Rosaria Scozzari,Heeran Makkan,Shay Tzur,David Comas,Jaume Bertranpetit,Lluis Quintana-Murci,Chris Tyler-Smith,R. Spencer Wells,Saharon Rosset,Saharon Rosset +15 more
TL;DR: The tree phylogeny and coalescence calculations suggest that Khoisan matrilineal ancestry diverged from the rest of the human mtDNA pool 90,000-150,000 years before present and that at least five additional, currently extant maternal lineages existed during this period in parallel.
Journal ArticleDOI
Did our species evolve in subdivided populations across Africa, and why does it matter?
Eleanor M. L. Scerri,Eleanor M. L. Scerri,Mark G. Thomas,Andrea Manica,Philipp Gunz,Jay T. Stock,Jay T. Stock,Chris Stringer,Matt Grove,Huw S. Groucutt,Huw S. Groucutt,Axel Timmermann,G. Philip Rightmire,Francesco d'Errico,Francesco d'Errico,Christian A. Tryon,Nick Drake,Alison S. Brooks,Robin Dennell,Richard Durbin,Richard Durbin,Brenna M. Henn,Julia A. Lee-Thorp,Peter B deMenocal,Michael D. Petraglia,Jessica C. Thompson,Aylwyn Scally,Lounès Chikhi,Lounès Chikhi +28 more
TL;DR: It is argued that the chronology and physical diversity of Pleistocene human fossils and the African archaeological record support an emerging view of a highly structured African prehistory that should be considered in human evolutionary inferences, prompting new interpretations, questions, and interdisciplinary research directions.
Journal ArticleDOI
The environmental context for the origins of modern human diversity: a synthesis of regional variability in African climate 150,000-30,000 years ago.
Margaret Whiting Blome,Andrew S. Cohen,Christian A. Tryon,Alison S. Brooks,Joellen L. Russell +4 more
TL;DR: It is argued that at a continental scale, population and climate changes were asynchronous and likely occurred under different regimes of climate forcing, creating alternating opportunities for migration into adjacent regions, and strongly support the hypothesis of hominin occupation of the Sahara during discrete humid intervals ~135-115 ka and 105-75 ka.
Journal ArticleDOI
100,000 Years of African monsoon variability recorded in sediments of the Nile margin
Marie Revel,Emmanuelle Ducassou,Francis E. Grousset,Stefano M. Bernasconi,Sébastien Migeon,Sidonie Révillon,Jean Mascle,Anne Murat,Sébastien Zaragosi,Delphine Bosch +9 more
TL;DR: In this article, multiproxy analyses were performed on core MS27PT recovered in hemipelagic sediments deposited on the Nile margin in order to reconstruct Nile River palaeohydrological fluctuations during the last 100,000 years.
References
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Book
Textbook of Pollen Analysis
Knut Faegri,Johannes Iversen +1 more
TL;DR: In this paper, the authors discuss the production and dispersal of Pollen Grains, where Pollen is found, how it is recovered, and where it comes from.
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The revolution that wasn't: a new interpretation of the origin of modern human behavior.
Sally McBrearty,Alison S. Brooks +1 more
TL;DR: The African Middle and early Late Pleistocene hominid fossil record is fairly continuous and in it can be recognized a number of probably distinct species that provide plausible ancestors for H. sapiens, and suggests a gradual assembling of the package of modern human behaviors in Africa, and its later export to other regions of the Old World.
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TL;DR: For example, this paper found that between 8 and 6 million years ago, there was a global increase in the biomass of plants using C4 photosynthesis as indicated by changes in the carbon isotope ratios of fossil tooth enamel in Asia, Africa, North America and South America.
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