Timing and causes of North African wet phases during the last glacial period and implications for modern human migration

Hoffmann, Dirk L., Rogerson, Mike, Spötl, Christoph, Luetscher, Marc, Vance, Derek, Osborne, Anne Helen, Fello, Nuri M. and Moseley, Gina E. (2016) Timing and causes of North African wet phases during the last glacial period and implications for modern human migration Scientific Reports, 6 (36367). DOI 10.1038/srep36367.

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Abstract

We present the first speleothem-derived central North Africa rainfall record for the last glacial period.
The record reveals three main wet periods at 65-61 ka, 52.5-50.5 ka and 37.5-33 ka that lead obliquity
maxima and precession minima. We find additional minor wet episodes that are synchronous with
Greenland interstadials. Our results demonstrate that sub-tropical hydrology is forced by both orbital
cyclicity and North Atlantic moisture sources. The record shows that after the end of a Saharan wet
phase around 70 ka ago, North Africa continued to intermittently receive substantially more rainfall
than today, resulting in favourable environmental conditions for modern human expansion. The
encounter and subsequent mixture of Neanderthals and modern humans – which, on genetic evidence,
is considered to have occurred between 60 and 50 ka – occurred synchronously with the wet phase
between 52.5 and 50.5 ka. Based on genetic evidence the dispersal of modern humans into Eurasia
started less than 55 ka ago. This may have been initiated by dry conditions that prevailed in North Africa
after 50.5 ka. The timing of a migration reversal of modern humans from Eurasia into North Africa is
suggested to be coincident with the wet period between 37.5 and 33 ka.

Document Type: Article
Additional Information: WOS:000386981200001
Keywords: Hydrology, paleoclimate
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
DOI etc.: 10.1038/srep36367
ISSN: 2045-2322
Date Deposited: 04 Nov 2016 08:22
Last Modified: 02 May 2017 13:41
URI: http://eprints.uni-kiel.de/id/eprint/34560

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