Late Pleistocene climate change and the global expansion of anatomically modern humans

Edited by James O’Connell, University of Utah, Salt Lake City, UT, and approved August 17, 2012 (received for review June 6, 2012)
September 17, 2012
109 (40) 16089-16094


The extent to which past climate change has dictated the pattern and timing of the out-of-Africa expansion by anatomically modern humans is currently unclear [Stewart JR, Stringer CB (2012) Science 335:1317–1321]. In particular, the incompleteness of the fossil record makes it difficult to quantify the effect of climate. Here, we take a different approach to this problem; rather than relying on the appearance of fossils or archaeological evidence to determine arrival times in different parts of the world, we use patterns of genetic variation in modern human populations to determine the plausibility of past demographic parameters. We develop a spatially explicit model of the expansion of anatomically modern humans and use climate reconstructions over the past 120 ky based on the Hadley Centre global climate model HadCM3 to quantify the possible effects of climate on human demography. The combinations of demographic parameters compatible with the current genetic makeup of worldwide populations indicate a clear effect of climate on past population densities. Our estimates of this effect, based on population genetics, capture the observed relationship between current climate and population density in modern hunter–gatherers worldwide, providing supporting evidence for the realism of our approach. Furthermore, although we did not use any archaeological and anthropological data to inform the model, the arrival times in different continents predicted by our model are also broadly consistent with the fossil and archaeological records. Our framework provides the most accurate spatiotemporal reconstruction of human demographic history available at present and will allow for a greater integration of genetic and archaeological evidence.

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We acknowledge financial support from the Biotechnology and Biological Sciences Research Council (F.B. and A.M.) and the Leverhulme Trust (A.M.).

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Published in

Go to Proceedings of the National Academy of Sciences
Go to Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences
Vol. 109 | No. 40
October 2, 2012
PubMed: 22988099


Submission history

Published online: September 17, 2012
Published in issue: October 2, 2012


  1. human dispersals
  2. colonization
  3. population bottlenecks
  4. net primary productivity
  5. most recent common ancestor


We acknowledge financial support from the Biotechnology and Biological Sciences Research Council (F.B. and A.M.) and the Leverhulme Trust (A.M.).


This article is a PNAS Direct Submission.



Anders Eriksson1 [email protected]
Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, England;
Lia Betti
Department of Anthropology, University of Kent, Kent CT2 7NR, England;
Andrew D. Friend
Department of Geography, University of Cambridge, Cambridge CB2 3EN, England;
Stephen J. Lycett
Department of Anthropology, University of Kent, Kent CT2 7NR, England;
Joy S. Singarayer
School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, England; and
Noreen von Cramon-Taubadel
Department of Anthropology, University of Kent, Kent CT2 7NR, England;
Paul J. Valdes
School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, England; and
Francois Balloux
Department of Genetics, Environment and Evolution, University College London, London WC1E 6BT, England
Andrea Manica1 [email protected]
Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, England;


To whom correspondence may be addressed. E-mail: [email protected] or [email protected].
Author contributions: A.E., F.B., and A.M. designed research; A.E., L.B., A.D.F., S.J.L., J.S.S., N.v.C.-T., P.J.V., F.B., and A.M. performed research; A.E. and A.M. contributed new reagents/analytic tools; A.E. and A.M. analyzed data; and A.E. and A.M. wrote the paper.

Competing Interests

The authors declare no conflict of interest.

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    Late Pleistocene climate change and the global expansion of anatomically modern humans
    Proceedings of the National Academy of Sciences
    • Vol. 109
    • No. 40
    • pp. 15967-16393







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