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Environmental and Behavioral Evidence Pertaining to the Evolution of Early Homo

Richard Potts
Current Anthropology
Vol. 53, No. S6, Human Biology and the Origins of Homo (December 2012), pp. S299-S317
DOI: 10.1086/667704
Stable URL:
Page Count: 19
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East African paleoenvironmental data increasingly inform an understanding of environmental dynamics. This understanding focuses less on habitat reconstructions at specific sites than on the regional trends, tempo, and amplitudes of climate and habitat change. Sole reliance on any one indicator, such as windblown dust or lake sediments, gives a bias toward strong aridity or high moisture as the driving force behind early human evolution. A synthesis of geological data instead offers a new paleoenvironmental framework in which alternating intervals of high and low climate variability provided the dynamic context in which East African Homo evolved. The Oldowan behavioral record presents further clues about how early Homo and Homo erectus responded to East African environmental change. Shifting conditions of natural selection, which were triggered by climatic variability, helped shape the adaptability of Oldowan hominins. Together, the behavioral and environmental evidence indicates the initial adaptive foundation for the dispersal of H. erectus and the persistence of Homo. In particular, overall dietary expansion made possible by the making and transport of stone tools compensated for increased locomotor and foraging costs and provided effective behavioral-ecological responses to resource instability during the early evolution of Homo.

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This item contains 120 references.

References Cited
  • ['Aiello, Leslie C., and Peter Wheeler. 1995. The expensive-tissue hypothesis: the brain and the digestive system in human and primate evolution. Current Anthropology 36:199–221.']
  • ['Ambrose, Stanley H., and Nancy E. Sikes. 1991. Soil organic carbon isotopic evidence for vegetation change in the Kenya Rift Valley. Science 253:1402–1405.']
  • ['Antón, Susan C. 2003. Natural history of Homo erectus. Yearbook of Physical Anthropology 46:126–170.']
  • ['———. 2012. Early Homo: who, when, and where. Current Anthropology 53(suppl. 6):S278–S298.']
  • ['Antón, Susan C., William R. Leonard, and Marcia L. Robertson. 2002. An ecomorphological model of the initial hominid dispersal from Africa. Journal of Human Evolution 43:773–785.']
  • ['Antón, Susan C., and J. Josh Snodgrass. 2012. Origins and evolution of genus Homo: new perspectives. Current Anthropology 53(suppl. 6):S479–S496.']
  • ['Antón, Susan C., and Carl C. Swisher III. 2004. Early dispersals of Homo from Africa. Annual Review of Anthropology 33:271–296.']
  • ['Ashley, Gail M. 2007. Orbital rhythms, monsoons, and playa lake response, Olduvai basin, equatorial East Africa (ca. 1.85–1.74 Ma). Geology 35:1091–1094.']
  • ['Behrensmeyer, Anna K., Nancy E. Todd, Richard Potts, and Geraldine E. McBrinn. 1997. Late Pliocene faunal turnover in the Turkana basin, Kenya and Ethiopia. Science 278:1589–1594.']
  • ['Binford, Lewis R. 1981. Bones: ancient men and modern myths. New York: Academic Press.']
  • ['Blumenschine, Robert J. 1991. Hominid carnivory and foraging strategies, and the socio-economic function of early archaeological sites. Philosophical Transactions of the Royal Society B: Biological Sciences 334:211–221.']
  • ['Bobe, René, Zeresenay Alemseged, and Anna K. Behrensmeyer, eds. 2007. Hominin environments in the East African Pliocene: an assessment of the faunal evidence. New York: Springer.']
  • ['Bobe, René, and Anna K. Behrensmeyer. 2004. The expansion of grassland ecosystems in Africa in relation to mammalian evolution and the origin of the genus Homo. Palaeogeography, Palaeoclimatology, Palaeoecology 207:399–420.']
  • ['Bobe, René, Anna K. Behrensmeyer, and Ralph E. Chapman. 2002. Faunal change, environmental variability and late Pliocene hominin evolution. Journal of Human Evolution 42:475–497.']
  • ['Bobe, René, Anna K. Behrensmeyer, Gerald G. Eck, and John M. Harris. 2007. Patterns of abundance and diversity in late Cenozoic bovids from the Turkana and Hadar basins, Kenya and Ethiopia. In Hominin environments in the East African Pliocene: an assessment of the faunal evidence. René Bobe, Zeresenay Alemseged, and Anna K. Behrensmeyer, eds. Pp. 129–157. New York: Springer.']
  • ['Bobe, René, and Gerald G. Eck. 2001. Response of African bovids to Pliocene climatic change. Paleobiology 27(suppl. 2):1–47.']
  • ['Bonnefille, Raymonde. 1995. A reassessment of the Plio-Pleistocene pollen record of East Africa. In Paleoclimate and evolution, with emphasis on human origins. Elizabeth S. Vrba, George H. Denton, Timothy C. Partridge, and Lloyd H. Burckle, eds. Pp. 299–310. New Haven, CT: Yale University Press.']
  • ['Bramble, Dennis M., and Daniel E. Lieberman. 2004. Endurance running and the evolution of Homo. Nature 432:345–352.']
  • ['Braun, David R., John W. K. Harris, Naomi E. Levin, Jack T. McCoy, Andy I. R. Herries, Marion K. Bamford, Laura C. Bishop, Brian G. Richmond, and Mzalendo Kibunjia. 2010. Early hominin diet included diverse terrestrial and aquatic animals 1.95 Ma in East Turkana, Kenya. Proceedings of the National Academy of Sciences of the USA 107:10002–10007.']
  • ['Braun, David R., Thomas Plummer, Peter Ditchfield, Joseph V. Ferraro, David Maina, Laura C. Bishop, and Richard Potts. 2008. Oldowan behavior and raw material transport: perspectives from the Kanjera Formation. Journal of Archaeological Science 35:2329–2345.']
  • ['Campisano, Christopher J., and Craig S. Feibel. 2007. Connecting local environmental sequences to global climate patterns: evidence from the hominin-bearing Hadar Formation, Ethiopia. Journal of Human Evolution 53:515–527.']
  • ['Carbone, Chris, Amber Teacher, and J. Marcus Rowcliffe. 2007. The costs of carnivory. PLoS Biology 5(2):e22, doi:10.1371/journal.pbio.0050022.']
  • ['Cerling, Thure E. 1992. Development of grasslands and savannas in East Africa during the Neogene. Palaeogeography, Palaeoclimatology, Palaeoecology 97:241–247.']
  • ['Cerling, Thure E., and Richard L. Hay. 1986. An isotopic study of paleosol carbonates from Olduvai Gorge. Quaternary Research 25:63–78.']
  • ['Cerling, Thure E., Jonathan G. Wynn, Samuel A. Andanje, Michael I. Bird, David Kimutai Korir, Naomi E. Levin, William Mace, Anthony N. Macharia, Jay Quade, and Christopher H. Remien. 2011. Woody cover and hominin environments in the past 6 million years. Nature 476:51–56.']
  • ['Clemens, Steven C. 1998. Dust response to seasonal atmospheric forcing: proxy evaluation and forcing. Paleoceanography 13:471–490.']
  • ['de Heinzelin, Jean, J. Desmond Clark, Tim White, William Hart, Paul Renne, Giday WoldeGabriel, Yonas Beyene, and Elisabeth Vrba. 1999. Environment and behavior of 2.5-million-year-old Bouri hominids. Science 284:625–629.']
  • ['Deino, Alan L. 2012. 40Ar/39Ar dating of Bed I, Olduvai Gorge, Tanzania, and the chronology of early Pleistocene climate change. Journal of Human Evolution 63:251–273.']
  • ['Deino, Alan L., John D. Kingston, Jonathan M. Glen, Robert K. Edgar, and Andrew Hill. 2006. Precessional forcing of lacustrine sedimentation in the late Cenozoic Chemeron basin, Central Kenya Rift. Earth and Planetary Science Letters 247:41–60.']
  • ['Delagnes, Anne, and Hélène Roche. 2005. Late Pliocene hominid knapping skills: the case of Lokalalei 2C, West Turkana, Kenya. Journal of Human Evolution 48:435–472.']
  • ['de la Torre, Ignacio. 2004. Omo revisited. Current Anthropology 45:439–465.']
  • ['deMenocal, Peter B. 1995. Plio-Pleistocene African climate. Science 270:53–59.']
  • ['———. 2004. African climate change and faunal evolution during the Pliocene-Pleistocene. Earth and Planetary Science Letters 220:3–24.']
  • ['———. 2011. Climate and human evolution. Science 331:540–541.']
  • ['Domínguez-Rodrigo, Manuel, Rebeca Barba, and Charles P. Egeland. 2007. Deconstructing Olduvai: a taphonomic study of the Bed I sites. Dordrecht: Springer.']
  • ['Domínguez-Rodrigo, Manuel, Travis Rayne Pickering, Sileshi Semaw, and Michael J. Rogers. 2005. Cutmarked bones from Pliocene archaeological sites at Gona, Ethiopia: implications for the function of the world’s oldest stone tools. Journal of Human Evolution 48:109–121.']
  • ['Donadio, Emiliano, and Steven W. Buskirk. 2006. Diet, morphology, and interspecific killing in carnivora. American Naturalist 167:524–536.']
  • ['Feakins, Sarah J., Peter B. deMenocal, and Timothy I. Eglinton. 2005. Biomarker records of late Neogene changes in northeast African vegetation. Geology 33:977–980.']
  • ['Feibel, Craig S. 1997. Debating the environmental factors in hominid evolution. Geological Society of America Today 7(3):1–7.']
  • ['Feibel, Craig S., John M. Harris, and Francis H. Brown. 1991. Palaeoenvironmental context for the late Neogene of the Turkana basin. In The fossil ungulates: geology, fossil artiodactyls, and palaeoenvironments, vol. 3 of Koobi Fora research project. John M. Harris, ed. Pp. 321–370. Oxford: Clarendon.']
  • ['Ferraro, Joseph V. 2007. Broken bones and smashed stones: on the foraging ecology of Oldowan hominins. PhD dissertation, University of California, Los Angeles.']
  • ['Ferring, Reid, Oriol Oms, Jordi Agustí, Francesco Berna, Medea Nioradze, Teona Shelia, Martha Tappen, Abesalom Vekua, David Zhvania, and David Lordkipanidze. 2011. Earliest human occupations at Dmanisi (Georgian Caucasus) dated to 1.85–1.78 Ma. Proceedings of the National Academy of Sciences of the USA 108:10432–10436.']
  • ['Frost, Stephen R. 2007. African Pliocene and Pleistocene cercopithecid evolution and global climatic change. In Hominin environments in the East African Pliocene: an assessment of the faunal evidence. René Bobe, Zeresenay Alemseged, and Anna K. Behrensmeyer, eds. Pp. 51–76. New York: Springer.']
  • ['Ghosh, Prosenjit, Jess Adkins, Hagit Affek, Brian Balta, Weifu Guo, Edwin A. Schauble, Dan Schrag, and John M. Eiler. 2006. 13C-18O bonds in carbonate minerals: a new kind of paleothermometer. Geochimica et Cosmochimica Acta 70:1439–1456.']
  • ['Goldman-Neuman, Talia, and Erella Hovers. 2009. Methodological issues in the study of Oldowan raw material selectivity: insights from A. L. 894 (Hadar, Ethiopia). In Interdisciplinary approaches to the Oldowan. Erella Hovers and David R. Braun, eds. Pp. 71–84. Dordrecht: Springer.']
  • ['———. 2011. Raw material selectivity in Late Pliocene Oldowan sites in the Makaamitalu basin, Hadar, Ethiopia. Journal of Human Evolution 62:353–366.']
  • ['Grove, Matt. 2011. Speciation, diversity, and Mode 1 technologies: the impact of variability selection. Journal of Human Evolution 61:306–319.']
  • ['Gursky-Doyen, Sharon, and K. A. I. Nekaris, eds. 2006. Primate anti-predator strategies. New York: Springer.']
  • ['Hay, Richard L. 1976. Geology of the Olduvai Gorge. Berkeley: University of California Press.']
  • ['Herries, Andy I. R., Darren Curnoe, and Justin W. Adams. 2009. A multi-disciplinary seriation of early Homo and Paranthropus bearing palaeocaves in southern Africa. Quaternary International 202:14–28.']
  • ['Herries, Andy I. R., and John Shaw. 2011. Palaeomagnetic analysis of the Sterkfontein palaeocave deposits: age implications for the hominin fossils and stone tool industries. Journal of Human Evolution 60:523–539.']
  • ['Hilgen, Frederik J., Hayfaa Abdul Aziz, Wout Krijgsman, Cor G. Langereis, Lucas J. Lourens, Johan E. Meulenkamp, Isabella Raffi, et al. 1999. Present status of the astronomical (polarity) time-scale for the Mediterranean Late Neogene. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 357:1931–1947.']
  • ['Holliday, Trenton W. 2012. Body size, body shape, and the circumscription of the genus Homo. Current Anthropology 53(suppl. 6):S330–S345.']
  • ['Howell, F. Clark, Paul Haesaerts, and Jean de Heinzelin. 1987. Depositional environments, archeological occurrences and hominids from members E and F of the Shungura Formation (Omo basin, Ethiopia). Journal of Human Evolution 16:665–700.']
  • ['Isaac, Glynn L. 1984. The archaeology of human origins: studies of the Lower Pleistocene in East Africa. Advances in World Archaeology 3:1–87.']
  • ['Joordens, Josephine C. A., Hubert B. Vonhof, Craig S. Feibel, Lucas J. Lourens, Guillaume Dupont-Nivet, Jeroen H. J. L. van der Lubbe, Mark J. Sier, Gareth R. Davies, and Dick Kroon. 2011. An astronomically-tuned climate framework for hominins in the Turkana basin. Earth and Planetary Science Letters 307:1–8.']
  • ['Kelt, Douglas A., and Dirk Van Vuren. 1999. Energetic constraints and the relationship between body size and home range area in mammals. Ecology 80:337–340.']
  • ['Kimbel, William H. 2009. The origin of Homo. In The first humans. Frederick E. Grine, John G. Fleagle, and Richard E. Leakey, eds. Pp. 31–37. New York: Springer.']
  • ['Kimbel, William H., Robert C. Walter, Donald C. Johanson, Kaye E. Reed, James L. Aronson, Zelalem Assefa, Curtis W. Marean, et al. 1996. Late Pliocene Homo and Oldowan tools from the Hadar Formation (Kada Hadar member), Ethiopia. Journal of Human Evolution 31:549–561.']
  • ['Kingston, John D. 2007. Shifting adaptive landscapes: progress and challenges in reconstructing early hominid environments. Yearbook of Physical Anthropology 50:20–58.']
  • ['Kingston, John D., Alan L. Deino, Robert K. Edgar, and Andrew Hill. 2007. Astronomically forced climate change in the Kenyan Rift Valley 2.7–2.55 Ma: implications for the evolution of early hominin ecosystems. Journal of Human Evolution 53:487–503.']
  • ['Kuzawa, Christopher W., and Jared M Bragg. 2012. Plasticity in human life history strategy: implications for contemporary human variation and the evolution of genus Homo. Current Anthropology 53(suppl. 6):S369–S382.']
  • ['Leakey, Mary D. 1971. Olduvai Gorge, vol. 3. Cambridge: Cambridge University Press.']
  • ['Lepre, Christopher J., Rhonda L. Quinn, Josephine C. A. Joordens, Carl C. Swisher III, and Craig S. Feibel. 2007. Plio-Pleistocene facies environments from the KBS member, Koobi Fora Formation: implications for climate controls on the development of lake-margin hominin habitats in the northeast Turkana basin (northwest Kenya). Journal of Human Evolution 53:504–514.']
  • ['Leroy, Suzanne, and Lydie Dupont. 1994. Development of vegetation and continental aridity in northwestern Africa during the Late Pliocene: the pollen record of ODP Site 658. Palaeogeography, Palaeoclimatology, Palaeoecology 109:295–316.']
  • ['Levin, Naomi E., Francis H. Brown, Anna K. Behrensmeyer, René Bobe, and Thure E. Cerling. 2011. Paleosol carbonates from the Omo group: isotopic records of local and regional environmental change in East Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 307:75–89.']
  • ['Levin, Naomi E., Jay Quade, Scott W. Simpson, Sileshi Semaw, and Michael Rogers. 2004. Isotopic evidence for Plio-Pleistocene environmental change at Gona, Ethiopia. Earth and Planetary Science Letters 219:93–110.']
  • ['Lewis, Margaret E., and Lars Werdelin. 2007. Patterns of change in the Plio-Pleistocene carnivorans of eastern Africa. In Hominin environments in the East African Pliocene: an assessment of the faunal evidence. René Bobe, Zeresenay Alemseged, and Anna K. Behrensmeyer, eds. Pp. 77–105. New York: Springer.']
  • ['Lordkipanidze, David, Tea Jashashvili, Abesalom Vekua, Marcia S. Ponce de León, Christoph P. E. Zollikofer, G. Philip Rightmire, Herman Pontzer, et al. 2007. Postcranial evidence from early Homo from Dmanisi, Georgia. Nature 449:305–310.']
  • ['Maslin, Mark A., and Martin H. Trauth. 2009. Plio-Pleistocene East African pulsed climate variability and its influence on early human evolution. In The first humans: origin and early evolution of the genus Homo. Frederick E. Grine, John G. Fleagle, and Richard E. Leakey, eds. Pp. 151–158. New York: Springer.']
  • ['Migliano, Andrea Bamberg, and Myrtille Guillon. 2012. The effects of mortality, subsistence, and ecology on human adult height and implications for Homo evolution. Current Anthropology 53(suppl. 6):S359–S368.']
  • ['Nagy, Ken A., Isabelle A. Girard, and Tracey K. Brown. 1999. Energetics of free-ranging mammals, reptiles, and birds. Annual Review of Nutrition 19:247–277.']
  • ['Owen, R. Bernhart, Richard Potts, and Anna K. Behrensmeyer. 2009. Reply to the comment on “Diatomaceous sediments and environmental change in the Pleistocene Olorgesailie Formation, southern Kenya Rift Valley” by R. Bernhart Owen, Richard Potts, Anna K. Behrensmeyer, and Peter Ditchfield. Palaeogeography, Palaeoclimatology, Palaeoecology 282:147–148.']
  • ['Passey, Benjamin H., Naomi E. Levin, Thure E. Cerling, Francis H. Brown, and John M. Eiler. 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 USA 107:11245–11249.']
  • ['Pickering, Robyn, Paul H. G. M. Dirks, Zubair Jinnah, Darryl J. de Ruiter, Steven E. Churchill, Andy I. R. Herries, Jon D. Woodhead, John C. Hellstrom, and Lee R. Berger. 2011. Australopithecus sediba at 1.977 Ma and implications for the origins of the genus Homo. Science 333:1421–1423.']
  • ['Plummer, Thomas W. 2004. Flaked stones and old bones: biological and cultural evolution at the dawn of technology. Yearbook of Physical Anthropology 47:118–164.']
  • ['Plummer, Thomas W., Peter W. Ditchfield, Laura C. Bishop, John D. Kingston, Joseph V. Ferraro, David R. Braun, Fritz Hertel, and Richard Potts. 2009. Oldest evidence of toolmaking hominins in a grassland-dominated ecosystem. PLoS ONE 4(9):e7199, doi:10.1371/journal.pone.0007199.']
  • ['Pontzer, Herman. 2012. Ecological energetics in early Homo. Current Anthropology 53(suppl. 6):S346–S358.']
  • ['Pontzer, Herman, Campbell Rolian, G. Philip Rightmire, Tea Jashashvili, Marcia S. Ponce de León, David Lordkipanidze, and Christoph P. E. Zollikofer. 2010. Locomotor anatomy and biomechanics of the Dmanisi hominins. Journal of Human Evolution 58:492–504.']
  • ['Potts, Richard. 1988. Early hominid activities at Olduvai. New York: Aldine.']
  • ['———. 1991. Why the Oldowan? Plio-Pleistocene toolmaking and the transport of resources. Journal of Anthropological Research 47:153–176.']
  • ['———. 1996a. Evolution and climate variability. Science 273:922–923.']
  • ['———. 1996b. Humanity’s descent: the consequences of ecological instability. New York: Morrow.']
  • ['———. 1998a. Environmental hypotheses of hominin evolution. Yearbook of Physical Anthropology 41:93–136.']
  • ['———. 1998b. Variability selection in hominid evolution. Evolutionary Anthropology 7:81–96.']
  • ['———. 2002. Complexity and adaptability in human evolution. In Probing human origins. Morris Goodman and Anne Moffat, eds. Pp. 33–57. Cambridge, MA: American Academy of Arts and Sciences.']
  • ['———. 2007. Environmental hypotheses of Pliocene human evolution. In Hominin environments in the East African Pliocene: an assessment of the faunal evidence. René Bobe, Zeresenay Alemseged, and Anna K. Behrensmeyer, eds. Pp. 25–50. New York: Springer.']
  • ['Potts, Richard, and Pat Shipman. 1981. Cutmarks made by stone tools on bones from Olduvai Gorge, Tanzania. Nature 291:577–580.']
  • ['Potts, Richard, and Robin Teague. 2010. Behavioral and environmental background to “Out of Africa I” and the arrival of Homo erectus in East Asia. In Out of Africa I: the first hominin colonization of Eurasia. John G. Fleagle, John J. Shea, Frederick E. Grine, Andrea L. Baden, and Richard E. Leakey, eds. Pp. 67–85. New York: Springer.']
  • ['Quade, Jay, Naomi Levin, Sileshi Semaw, Dietrich Stout, Paul Renne, Michael Rogers, and Scott Simpson. 2004. Paleoenvironments of the earliest stone toolmakers, Gona, Ethiopia. Geological Society of America Bulletin 116:1529–1544.']
  • ['Quade, Jay, Naomi E. Levin, Scott W. Simpson, Robert Butler, William C. McIntosh, Sileshi Semaw, Lynnette Kleinsasser, Guillaume Dupont-Nivet, Paul Renne, and Nelia Dunbar. 2008. The geology of Gona, Afar, Ethiopia. In The geology of early humans in the Horn of Africa. Jay Quade and Jonathan C. Wynn, eds. Special Paper 446. Pp. 1–31. Boulder, CO: Geological Society of America.']
  • ['Quinn, Rhonda L., Christopher J. Lepre, James D. Wright, and Craig S. Feibel. 2007. Paleogeographic variations of pedogenic carbonate δ13C values from Koobi Fora, Kenya: implications for floral compositions of Plio-Pleistocene hominin environments. Journal of Human Evolution 53:560–573.']
  • ['Reed, Kaye E. 1997. Early hominid evolution and ecological change through the African Plio-Pleistocene. Journal of Human Evolution 32:289–322.']
  • ['———. 2008. Paleoecological patterns at the Hadar hominin site, Afar Regional State, Ethiopia. Journal of Human Evolution 54:743–768.']
  • ['Rossignol-Strick, Martine. 1983. African monsoons, an immediate climate response to orbital insolation. Nature 304:46–49.']
  • ['Ruddiman, William F. 2001. Earth’s climate: past and future. New York: W. H. Freeman.']
  • ['Ruff, Christopher B., Erik Trinkaus, Alan Walker, and Clark Spencer Larsen. 1993. Postcranial robusticity in Homo. 1. Temporal trends and mechanical interpretation. American Journal of Physical Anthropology 91:21–53.']
  • ['Ruff, Christopher B., and Alan Walker. 1993. Body size and body shape. In The Nariokotome Homo erectus skeleton. Alan C. Walker and Richard E. Leakey, eds. Pp. 234–265. Cambridge, MA: Harvard University Press.']
  • ['Sahnouni, Mohamed, Djillali Hadjouis, Jan van der Made, Abd-El-Kader Derradji, Antoni Canals, Mohamed Medig, Hocine Belahrech, Zoheir Harichane, and Merouane Rabhi. 2002. Further research at the Oldowan site of Aïn Hanech, north-eastern Algeria. Journal of Human Evolution 43:925–937.']
  • ['Schwartz, Gary T. 2012. Growth, development, and life history throughout the evolution of Homo. Current Anthropology 53(suppl. 6):S395–S408.']
  • ['Semaw, Sileshi, Michael J. Rogers, Jay Quade, Paul R. Renne, Robert F. Butler, Manuel Domínguez-Rodrigo, Dietrich Stout, William S. Hart, Travis Pickering, and Scott W. Simpson. 2003. 2.6-million-year-old stone tools and associated bones from OGS-6 and OGS-7, Gona, Afar, Ethiopia. Journal of Human Evolution 45:169–177.']
  • ['Sepulchre, Pierre, Gilles Ramstein, Frédéric Fluteau, Mathieu Schuster, Jean-Jacques Tiercelin, and Michel Brunet. 2006. Tectonic uplift and eastern Africa aridification. Science 313:1419–1423.']
  • ['Shipman, Pat, and Alan Walker. 1989. The costs of becoming a predator. Journal of Human Evolution 18:373–392.']
  • ['Stout, Dietrich, Jay Quade, Sileshi Semaw, Michael Rogers, and Naomi E. Levin. 2005. Raw material selectivity of the earliest stone tool makers at Gona, Afar, Ethiopia. Journal of Human Evolution 48(4):365–380.']
  • ['Stout, Dietrich, Sileshi Semaw, Michael J. Rogers, and Dominique Cauche. 2010. Technological variation in the earliest Oldowan from Gona, Afar, Ethiopia. Journal of Human Evolution 58:474–491.']
  • ['Trauth, Martin H., Juan C. Larrasoaña, and Manfred Mudelsee. 2009. Trends, rhythms and events in Plio-Pleistocene African climate. Quaternary Science Reviews 28:399–411.']
  • ['Trauth, Martin H., Mark A. Maslin, Alan L. Deino, Annett Junginger, Moses Lesoloyia, Eric O. Odada, Daniel O. Olago, Lydia A. Olaka, Manfred R. Strecker, and Ralph Tiedemann. 2010. Human evolution in a variable environment: the amplifier lakes of eastern Africa. Quaternary Science Reviews 29:2981–2988.']
  • ['Trauth, Martin H., Mark A. Maslin, Alan L. Deino, and Manfred R. Strecker. 2005. Late Cenozoic moisture history of East Africa. Science 309:2051–2053.']
  • ['Trauth, Martin H., Mark A. Maslin, Alan L. Deino, Manfred R. Strecker, Andreas G. N. Bergner, and Miriam Dühnforth. 2007. High- and low-latitude forcing of Plio-Pleistocene East African climate and human evolution. Journal of Human Evolution 53:475–486.']
  • ['Vrba, Elisabeth S. 1985. Environment and evolution: alternative causes of the temporal distribution of evolutionary events. South African Journal of Science 81:229–236.']
  • ['———. 1988. Late Pliocene climatic events and hominid evolution. In Evolutionary history of the “robust” australopithecines. Frederick E. Grine, ed. Pp. 405–426. New York: Aldine.']
  • ['———. 1992. Mammals as a key to evolutionary theory. Journal of Mammalogy 73:1–28.']
  • ['———. 1994. An hypothesis of heterochrony in response to climatic cooling and its relevance to early hominid evolution. In Integrative paths to the past. Robert S. Corruccini and Russell L. Ciochon, eds. Pp. 345–376. Englewood Cliffs, NJ: Prentice Hall.']
  • ['———. 1995a. The fossil record of African antelopes (Mammalia, Bovidae) in relation to human evolution and paleoclimate. In Paleoclimate and evolution, with emphasis on human origins. Elizabeth S. Vrba, George H. Denton, Timothy C. Partridge, and Lloyd H. Burckle, eds. Pp. 385–424. New Haven, CT: Yale University Press.']
  • ['———. 1995b. On the connections between paleoclimate and evolution. In Paleoclimate and evolution, with emphasis on human origins. Elizabeth S. Vrba, George H. Denton, Timothy C. Partridge, and Lloyd H. Burckle, eds. Pp. 24–45. New Haven, CT: Yale University Press.']
  • ['Vrba, Elizabeth S., George H. Denton, Timothy C. Partridge, and Lloyd H. Burckle, eds. 1995. Paleoclimate and evolution, with emphasis on human origins. New Haven, CT: Yale University Press.']
  • ['Wehausen, Rolf, and Hans-Jürgen Brumsack. 1999. Cyclic variations in the chemical composition of eastern Mediterranean Pliocene sediments: a key for understanding sapropel formation. Marine Geology 153:161–176.']
  • ['Wynn, Jonathan G. 2000. Paleosols, stable carbon isotopes, and paleoenvironmental interpretation of Kanapoi, Northern Kenya. Journal of Human Evolution 39:411–432.']
  • ['Zachos, James, Mark Pagani, Lisa Sloan, Ellen Thomas, and Katharina Billups. 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292:686–693.']
  • ['Zhu, Rixiang, Richard Potts, Fei Xie, Kenneth A. Hoffman, Chenglong L. Deng, C. D. Shi, Yongxin X. Pan, et al. 2004. New evidence regarding the earliest human presence at high northern latitudes in northeast Asia. Nature 431:559–562.']