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High-temperature environments of human evolution in East Africa based on bond ordering in paleosol carbonates

Passey, Benjamin H. and Levin, Naomi E. and Cerling, Thure E. and Brown, Francis H. and Eiler, John M. (2010) High-temperature environments of human evolution in East Africa based on bond ordering in paleosol carbonates. Proceedings of the National Academy of Sciences of the United States of America, 107 (25). pp. 11245-11249. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:20100713-093429004

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Abstract

Many important hominid-bearing fossil localities in East Africa are in regions that are extremely hot and dry. Although humans are well adapted to such conditions, it has been inferred that East African environments were cooler or more wooded during the Pliocene and Pleistocene when this region was a central stage of human evolution. Here we show that the Turkana Basin, Kenya—today one of the hottest places on Earth—has been continually hot during the past 4 million years. The distribution of ^(13)C-^(18)O bonds in paleosol carbonates indicates that soil temperatures during periods of carbonate formation were typically above 30 °C and often in excess of 35 °C. Similar soil temperatures are observed today in the Turkana Basin and reflect high air temperatures combined with solar heating of the soil surface. These results are specific to periods of soil carbonate formation, and we suggest that such periods composed a large fraction of integrated time in the Turkana Basin. If correct, this interpretation has implications for human thermophysiology and implies a long-standing human association with marginal environments.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1073/pnas.1001824107 DOIUNSPECIFIED
http://www.pnas.org/content/107/25/11245PublisherUNSPECIFIED
Additional Information:© 2010 by the National Academy of Sciences. Edited by Karl K. Turekian, Yale University, New Haven, CT, and approved May 14, 2010 (received for review February 12, 2010). Published online before print June 8, 2010. We thank A. Sessions, W. Brand, J. Eronen, and C. Baumgartner for technical advice; C. Remien for help with temperature measurements; D. Bramble, J. Quade, and S. Simpson for commenting on earlier versions of the manuscript; and the editor and reviewers for insightful comments and suggestions. We thank the Dreyfus Foundation and the National Science Foundation for supporting this research. Author contributions: B.H.P., N.E.L., T.E.C., F.H.B., and J.M.E. designed research; B.H.P., N.E.L., T.E.C., F.H.B., and J.M.E. performed research; B.H.P., N.E.L., T.E.C., F.H.B., and J.M.E. analyzed data; and B.H.P. wrote the paper.
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Funding AgencyGrant Number
Dreyfus Foundation UNSPECIFIED
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Subject Keywords:continental paleoclimate; clumped isotopes; soil temperature; hominid; bipedal locomotion
Record Number:CaltechAUTHORS:20100713-093429004
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20100713-093429004
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19020
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:13 Jul 2010 20:47
Last Modified:26 Dec 2012 12:13

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