Wet phases in the Sahara/Sahel region and human migration patterns in North Africa.
The carbon isotopic composition of individual plant leaf waxes (a proxy for C(3) vs. C(4) 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 C(3) 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 C(3) vegetation during the African Humid Period (early Holocene) and within Marine Isotope Stage (MIS) 3 ( approximately 50-45 ka) and MIS 5 ( approximately 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.
Castañeda
Isla S
IS
Department of Marine Organic Biogeochemistry, Royal Netherlands Institute for Sea Research, P O Box 59, 1790 AB Den Burg (Texel), The Netherlands. isla.castaneda@nioz.nl
Mulitza
Stefan
S
Schefuss
Enno
E
Lopes dos Santos
Raquel A
RA
Sinninghe Damsté
Jaap S
JS
Schouten
Stefan
S
D000352:Africa, Northern; D002247:Carbon Isotopes / Q000032:analysis; D002980:Climate; D004641:Emigration and Immigration / Q000266:history*; D019015:Geologic Sediments / Q000032:analysis; D049690:History, Ancient; D006801:Humans; D018515:Plant Leaves / Q000737:chemistry; D014885:Waxes / Q000737:chemistry
D002247:Carbon Isotopes; D014885:Waxes