Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/11068
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Environmental changes and the rise and fall of civilizations in the northern Horn of Africa: An approach combining deltaD analyses of land-plant derived fatty acids with multiple proxies in soil
Authors: Terwilliger, Valery J
Eshetu, Zewdu
Disnar, Jean-Robert
Jacob, Jeremy
Adderley, W Paul
Huang, Yongsong
Alexandre, Marcelo
Fogel, Marilyn L
Contact Email: w.p.adderley@stir.ac.uk
Keywords: Aksum
Soil
D'MT
Isotope
Climate Change
Charcoal
Holocene
Issue Date: 15-Jun-2013
Publisher: Elsevier
Citation: Terwilliger VJ, Eshetu Z, Disnar J, Jacob J, Adderley WP, Huang Y, Alexandre M & Fogel ML (2013) Environmental changes and the rise and fall of civilizations in the northern Horn of Africa: An approach combining deltaD analyses of land-plant derived fatty acids with multiple proxies in soil, Geochimica et Cosmochimica Acta, 111, pp. 140-161.
Abstract: The domains of the ancient polities D'MT and Aksum in the Horn of Africa's highlands are a superior natural system for evaluating roles of environmental change on the rise and fall of civilizations. To compare environmental changes of the times of the two polities, we analyzed stable hydrogen isotopic ratios (dD) of land-plant derived fatty acids (n-C26-30) and other proxies from soil sequences spanning the Holocene from the region. Three results suggest that trends in dD values unambiguously reflect changes in rainfall. First, increases in dD coincide with dry periods inferred from studies of eastern African lakes. Second, changes in dD values were parallel among sections during overlapping time intervals. Third, consideration of vegetation history did not alter directions of trends in dD values over time. By unambiguously recording precipitation, the dD values also enhanced interpretations of proxies that are affected by both climate and land clearing. Both D'MT (ca 2750-2350 cal y BP) and the Aksumite (ca 2100-1250 cal y BP) rose during wetter intervals of the drier part of the Holocene (after ca 6000 cal y BP). Analyses of charred matter indicated that fire had been a common agent of land clearing in all sites. The influence of climate on fire varied, however. Prior to the emergence of D'MT, dD values were correlated with C4:C3 plant ratios estimated from d13C values. There are no C4 trees and precipitation may have been the main influence on canopy openness. After ca 4300 cal y BP, there was no significant relationship between dD and C4:C3 plant ratios suggesting that factors such as fire influenced canopy openness regardless of climate. Furthermore, the impact of land clearance differed between sites and between D'MT and the Aksumite's times. In one site, the interval from 3550 cal y BP to the decline of D'MT had several anomalies that suggested dramatic increases in thermal severity of fire and human impact. Among these were a large contribution of charred matter to a high% total organic carbon that low hydrogen and oxygen indices suggest was severely altered by other factors than humification. These results support hypotheses about the rise of civilizations being favored by specific climatic conditions but suggest that patterns of land clearing differed during the declines of D'MT and the Aksumite.
Type: Journal Article
URI: http://hdl.handle.net/1893/11068
DOI Link: http://dx.doi.org/10.1016/j.gca.2012.10.040
Rights: The publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.
Affiliation: University of Kansas
University of Addis Ababa, Ethiopia
Université d’Orléans, France
Université d’Orléans, France
Biological and Environmental Sciences
Brown University
Federal University of Sergipe
Carnegie Institution for Science

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