Wet phases in the Sahara/Sahel region and human migration patterns in North Africa

Isla S. Castañeda, Stefan Mulitza, Enno Schefuß, Raquel A. Lopes dos Santos, Jaap S. Sinninghe Damsté, and Stefan Schouten
PNAS published ahead of print November 12, 2009 https://doi.org/10.1073/pnas.0905771106

  1. Edited by Thure E. Cerling, University of Utah, Salt Lake City, UT, and approved October 1, 2009 (received for review May 25, 2009)

Abstract

The carbon isotopic composition of individual plant leaf waxes (a proxy for C3 vs. C4 vegetation) in a marine sediment core collected from beneath the plume of Sahara-derived dust in northwest Africa reveals three periods during the past 192,000 years when the central Sahara/Sahel contained C3 plants (likely trees), indicating substantially wetter conditions than at present. Our data suggest that variability in the strength of Atlantic meridional overturning circulation (AMOC) is a main control on vegetation distribution in central North Africa, and we note expansions of C3 vegetation during the African Humid Period (early Holocene) and within Marine Isotope Stage (MIS) 3 (≈50–45 ka) and MIS 5 (≈120–110 ka). The wet periods within MIS 3 and 5 coincide with major human migration events out of sub-Saharan Africa. Our results thus suggest that changes in AMOC influenced North African climate and, at times, contributed to amenable conditions in the central Sahara/Sahel, allowing humans to cross this otherwise inhospitable region.

Footnotes

  • 1To whom correspondence should be addressed. E-mail: isla.castaneda{at}nioz.nl

  • Author contributions: I.S.C., S.M., E.S., and S.S. designed research; I.S.C., S.M., and R.A.L.d.S. performed research; I.S.C., S.M., E.S., R.A.L.d.S., J.S.S.D., and S.S. analyzed data; and I.S.C., S.M., E.S., and S.S. wrote the paper.

  • The authors declare no conflict of interest.

  • This article is a PNAS Direct Submission.

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Wet phases in the Sahara/Sahel region and human migration patterns in North Africa
Isla S. Castañeda, Stefan Mulitza, Enno Schefuß, Raquel A. Lopes dos Santos, Jaap S. Sinninghe Damsté, Stefan Schouten
Proceedings of the National Academy of Sciences Nov 2009, pnas.0905771106; DOI: 10.1073/pnas.0905771106
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