High-resolution vegetation and climate change associated with Pliocene Australopithecus afarensis

doi:10.1073/pnas.0401709101

High-resolution vegetation and climate change associated with Pliocene Australopithecus afarensis

^*Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement, Unité Mixte de Recherche 6635, Centre National de la Recherche Scientifique, B.P. 80, 13545 Aix-en-Provence Cedex 04, France; ^‡Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560-0112; ^§Institut des Sciences de l'Evolution, Unité Mixte de Recherche Centre National de la Recherche Scientifique 5554, Université Montpellier II, F-34095 Montpellier Cedex 05 France; and ^¶Laboratoire de Chronoécologie, Unité Mixte de Recherche 6565, Université de Franche Comté 25030 Besançon, France

Edited by Thure E. Cerling, University of Utah, Salt Lake City, UT (received for review March 11, 2004)

Abstract

Plio-Pleistocene global climate change is believed to have had an important influence on local habitats and early human evolution in Africa. Responses of hominin lineages to climate change have been difficult to test, however, because this procedure requires well documented evidence for connections between global climate and hominin environment. Through high-resolution pollen data from Hadar, Ethiopia, we show that the hominin Australopithecus afarensis accommodated to substantial environmental variability between 3.4 and 2.9 million years ago. A large biome shift, up to 5°C cooling, and a 200- to 300-mm/yr rainfall increase occurred just before 3.3 million years ago, which is consistent with a global marine δ¹⁸O isotopic shift.

Footnotes

↵ † To whom correspondence may be addressed. E-mail: bonnefille{at}cerege.fr or potts.rick{at}nmnh.si.edu.
This paper was submitted directly (Track II) to the PNAS office.
Abbrevations: SH, Sidi Hakoma; SHT, SH Tuff; KDB, Kada Damum Basalt; DD, Denen Dora; MTCO, mean temperature of the coldest month; PFT, plant functional type; STEP, steppe; TXWS, tropical xerophytic woods/scrub; XERO, temperate xerophytic woods/scrub; WAMF, warm mixed forest; BA, Best Analog; mya, million years ago.