A two-million-year-long hydroclimatic context for hominin evolution in southeastern Africa
|Author(s)||Caley Thibaut1, Extier Thomas1, 2, Collins James A.3, 4, Schefuss Enno5, Dupont Lydie5, Malaize Bruno1, Rossignol Linda1, Souron Antoine6, McClymont Erin L.7, Jimenez-Espejo Francisco J.8, Garcia-Comas Carmen9, 10, Eynaud Frederique1, Martinez Philippe1, Roche Didier M.2, 11, Jorry Stephan12, Charlier Karine1, Wary Melanie1, Gourves Pierre-Yves1, Billy Isabelle1, Giraudeau Jacques1|
|Affiliation(s)||1 : Univ Bordeaux, CNRS, EPOC, UMR 5805, Pessac, France.
2 : Univ Paris Saclay, CEA CNRS UVSQ, IPSL, LSCE, Gif Sur Yvette, France.
3 : GFZ German Res Ctr Geosci, Organ Surface Geochem Lab, Sect Geomorphol 5 1, Potsdam, Germany.
4 : Alfred Wegener Inst Helmholtz Ctr Polar & Marine, Bremerhaven, Germany.
5 : Univ Bremen, MARUM Ctr Marine Environm Sci, Bremen, Germany.
6 : Univ Bordeaux, CNRS, UMR 5199, PACEA, Pessac, France.
7 : Univ Durham, Dept Geog, Durham, England.
8 : JAMSTEC, Dept Biogeochem, Yokosuka, Kanagawa, Japan.
9 : JAMSTEC, Res & Dev Ctr Global Change, Yokohama, Kanagawa, Japan.
10 : Univ Vic Cent Univ Catalonia, Ecol Grp, Barcelona, Spain.
11 : Vrije Univ Amsterdam, Fac Sci Cluster Earth & Climate, Amsterdam, Netherlands.
12 : Inst Francais Rech Exploitat Mer IFREMER, Unite Geosci Marines, Plouzane, France.
|Source||Nature (0028-0836) (Nature Publishing Group), 2018-08 , Vol. 560 , N. 7716 , P. 76-79|
|WOS© Times Cited||56|
The past two million years of eastern African climate variability is currently poorly constrained, despite interest in understanding its assumed role in early human evolution1,2,3,4. Rare palaeoclimate records from northeastern Africa suggest progressively drier conditions2,5 or a stable hydroclimate6. By contrast, records from Lake Malawi in tropical southeastern Africa reveal a trend of a progressively wetter climate over the past 1.3 million years7,8. The climatic forcings that controlled these past hydrological changes are also a matter of debate. Some studies suggest a dominant local insolation forcing on hydrological changes9,10,11, whereas others infer a potential influence of sea surface temperature changes in the Indian Ocean8,12,13. Here we show that the hydroclimate in southeastern Africa (20–25° S) is controlled by interplay between low-latitude insolation forcing (precession and eccentricity) and changes in ice volume at high latitudes. Our results are based on a multiple-proxy reconstruction of hydrological changes in the Limpopo River catchment, combined with a reconstruction of sea surface temperature in the southwestern Indian Ocean for the past 2.14 million years. We find a long-term aridification in the Limpopo catchment between around 1 and 0.6 million years ago, opposite to the hydroclimatic evolution suggested by records from Lake Malawi. Our results, together with evidence of wetting at Lake Malawi, imply that the rainbelt contracted toward the Equator in response to increased ice volume at high latitudes. By reducing the extent of woodland or wetlands in terrestrial ecosystems, the observed changes in the hydroclimate of southeastern Africa—both in terms of its long-term state and marked precessional variability—could have had a role in the evolution of early hominins, particularly in the extinction of Paranthropus robustus.