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Foister TIF, Žliobaitė I, Wilson OE, Fortelius M, Tallavaara M. Homo heterogenus: Variability in early Pleistocene Homo environments. Evol Anthropol 2023; 32:373-385. [PMID: 37877200 DOI: 10.1002/evan.22005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 08/29/2023] [Accepted: 09/05/2023] [Indexed: 10/26/2023]
Abstract
To understand the ecological dominance of Homo sapiens, we need to investigate the origins of the plasticity that has enabled our colonization of the planet. We can approach this by exploring the variability of habitats to which different hominin populations have adapted over time. In this article, we draw upon and synthesize the current research on habitats of genus Homo during the early Pleistocene. We examined 121 published environmental reconstructions from 74 early Pleistocene sites or site phases to assess the balance of arguments in the research community. We found that, while grasslands and savannahs were prominent features of Homo habitats in the early Pleistocene, current research does not place early Pleistocene Homo, in any single environmental type, but in a wide variety of environments, ranging from open grasslands to forests. Our analysis also suggests that the first known dispersal of Homo out of Africa was accompanied by niche expansion.
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Affiliation(s)
- Tegan I F Foister
- Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland
| | - Indrė Žliobaitė
- Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland
- Department of Computer Science, University of Helsinki, Helsinki, Finland
- Finnish Museum of Natural History, LUOMUS, Helsinki, Finland
| | - Oscar E Wilson
- Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland
| | - Mikael Fortelius
- Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland
- Finnish Museum of Natural History, LUOMUS, Helsinki, Finland
| | - Miikka Tallavaara
- Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland
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2
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Peppe DJ, Cote SM, Deino AL, Fox DL, Kingston JD, Kinyanjui RN, Lukens WE, MacLatchy LM, Novello A, Strömberg CAE, Driese SG, Garrett ND, Hillis KR, Jacobs BF, Jenkins KEH, Kityo RM, Lehmann T, Manthi FK, Mbua EN, Michel LA, Miller ER, Mugume AAT, Muteti SN, Nengo IO, Oginga KO, Phelps SR, Polissar P, Rossie JB, Stevens NJ, Uno KT, McNulty KP. Oldest evidence of abundant C 4 grasses and habitat heterogeneity in eastern Africa. Science 2023; 380:173-177. [PMID: 37053309 DOI: 10.1126/science.abq2834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
The assembly of Africa's iconic C4 grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including hominins. C4 grasses are thought to have become ecologically dominant in Africa only after 10 million years ago (Ma). However, paleobotanical records older than 10 Ma are sparse, limiting assessment of the timing and nature of C4 biomass expansion. This study uses a multiproxy design to document vegetation structure from nine Early Miocene mammal site complexes across eastern Africa. Results demonstrate that between ~21 and 16 Ma, C4 grasses were locally abundant, contributing to heterogeneous habitats ranging from forests to wooded grasslands. These data push back the oldest evidence of C4 grass-dominated habitats in Africa-and globally-by more than 10 million years, calling for revised paleoecological interpretations of mammalian evolution.
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Affiliation(s)
- Daniel J Peppe
- Department of Geosciences, Baylor University, Waco, TX 76798, USA
| | - Susanne M Cote
- Department of Anthropology and Archaeology, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Alan L Deino
- Berkeley Geochronology Center, Berkeley, CA 94709, USA
| | - David L Fox
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - John D Kingston
- Department of Anthropology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rahab N Kinyanjui
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
- Max Planck Institute for Geoanthropology, D-07743 Jena, Germany
- Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA
| | - William E Lukens
- Department of Geology & Environmental Science, James Madison University, Harrisonburg, VA 22807, USA
| | - Laura M MacLatchy
- Department of Anthropology, University of Michigan, Ann Arbor, MI 48109, USA
- Museum of Paleontology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Alice Novello
- CEREGE, Aix-Marseille Université, CNRS, IRD, Collège de France, INRAE, 13545 Aix en Provence, France
- Department of Biology, Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - Caroline A E Strömberg
- Department of Biology, Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - Steven G Driese
- Department of Geosciences, Baylor University, Waco, TX 76798, USA
| | - Nicole D Garrett
- Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kayla R Hillis
- Department of Earth Sciences, Tennessee Tech University, Cookeville, TN 38505, USA
| | - Bonnie F Jacobs
- Roy M. Huffington Department of Earth Sciences, Southern Methodist University, Dallas, TX 75275, USA
| | - Kirsten E H Jenkins
- Department of Social Sciences, Tacoma Community College, Tacoma, WA 98466, USA
| | - Robert M Kityo
- Department of Zoology Entomology and Fisheries Sciences, Makerere University, Kampala, Uganda
| | - Thomas Lehmann
- Department Messel Research and Mammalogy, Senckenberg Research Institute and Natural History Museum, 60325 Frankfurt, Germany
| | - Fredrick K Manthi
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
| | - Emma N Mbua
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
| | - Lauren A Michel
- Department of Earth Sciences, Tennessee Tech University, Cookeville, TN 38505, USA
| | - Ellen R Miller
- Department of Anthropology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - Amon A T Mugume
- Department of Zoology Entomology and Fisheries Sciences, Makerere University, Kampala, Uganda
- Uganda National Museum, Department of Museums and Monuments, Ministry of Tourism, Wildlife and Antiquities, Kampala, Uganda
| | - Samuel N Muteti
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
- Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Isaiah O Nengo
- Turkana Basin Institute, Stony Brook University, Stony Brook, NY 11794, USA
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Kennedy O Oginga
- Department of Geosciences, Baylor University, Waco, TX 76798, USA
| | - Samuel R Phelps
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Pratigya Polissar
- Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - James B Rossie
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Nancy J Stevens
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, and Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH 45701, USA
| | - Kevin T Uno
- Division of Biology and Paleo Environment, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
| | - Kieran P McNulty
- Department of Anthropology, University of Minnesota, Minneapolis, MN 55455, USA
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3
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Longman DP, Dolan E, Wells JCK, Stock JT. Patterns of energy allocation during energetic scarcity; evolutionary insights from ultra-endurance events. Comp Biochem Physiol A Mol Integr Physiol 2023; 281:111422. [PMID: 37031854 DOI: 10.1016/j.cbpa.2023.111422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/06/2023] [Accepted: 04/06/2023] [Indexed: 04/11/2023]
Abstract
Exercise physiologists and evolutionary biologists share a research interest in determining patterns of energy allocation during times of acute or chronic energetic scarcity.. Within sport and exercise science, this information has important implications for athlete health and performance. For evolutionary biologists, this would shed new light on our adaptive capabilities as a phenotypically plastic species. In recent years, evolutionary biologists have begun recruiting athletes as study participants and using contemporary sports as a model for studying evolution. This approach, known as human athletic palaeobiology, has identified ultra-endurance events as a valuable experimental model to investigate patterns of energy allocation during conditions of elevated energy demand, which are generally accompanied by an energy deficit. This energetic stress provokes detectable functional trade-offs in energy allocation between physiological processes. Early results from this modelsuggest thatlimited resources are preferentially allocated to processes which could be considered to confer the greatest immediate survival advantage (including immune and cognitive function). This aligns with evolutionary perspectives regarding energetic trade-offs during periods of acute and chronic energetic scarcity. Here, we discuss energy allocation patterns during periods of energetic stress as an area of shared interest between exercise physiology and evolutionary biology. We propose that, by addressing the ultimate "why" questions, namely why certain traits were selected for during the human evolutionary journey, an evolutionary perspective can complement the exercise physiology literature and provide a deeper insight of the reasons underpinning the body's physiological response to conditions of energetic stress.
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Affiliation(s)
- Daniel P Longman
- School of Sport, Health and Exercise Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom.
| | - Eimear Dolan
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, Rheumatology Division, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil
| | - Jonathan C K Wells
- Childhood Nutrition Research Centre, UCL Institute of Child Health, London WC1N 1EH, United Kingdom
| | - Jay T Stock
- Department of Archaeology, University of Cambridge, Cambridge CB2 3QG, United Kingdom; Department of Anthropology, University of Western Ontario, Ontario, Canada
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4
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Stancampiano LM, Sistiaga A, Del Val DU, Aramendi J, Baquedano E, Mabulla A, Domínguez-Rodrigo M, Magill CR. New site at Olduvai Gorge (AGS, Bed I, 1.84 Mya) widens the range of locations where hominins engaged in butchery. Sci Rep 2022; 12:9794. [PMID: 35697774 PMCID: PMC9192694 DOI: 10.1038/s41598-022-14031-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/31/2022] [Indexed: 11/23/2022] Open
Abstract
Outstanding questions about human evolution include systematic connections between critical landscape resources-such as water and food-and how these shaped the competitive and biodiverse environment(s) that our ancestors inhabited. Here, we report fossil n-alkyl lipid biomarkers and their associated δ13C values across a newly discovered Olduvai Gorge site (AGS) dated to 1.84 million years ago, enabling a multiproxy analysis of the distributions of critical local landscape resources across an explicit locus of hominin activity. Our results reveal that AGS was a seasonally waterlogged, largely unvegetated lakeside site situated near an ephemeral freshwater river surrounded by arid-adapted C4 grasses. The sparse vegetation at AGS contrasts with reconstructed (micro)habitats at the other anthropogenic sites at Olduvai Gorge, suggesting that central-provisioning places depended more heavily on water access than vegetation viz. woody plants as is often observed for modern hunter-gatherers. As hominins at AGS performed similar butchering activities as at other Bed I sites, our results suggest they did not need the shelter of trees and thus occupied a competitive position within the predatory guild.
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Affiliation(s)
| | - Ainara Sistiaga
- University of Copenhagen, Copenhagen, Denmark
- Massachusetts Institute of Technology, Cambridge, USA
| | - David Uribelarrea Del Val
- Institute of Evolution in Africa (IDEA), University of Alcalá, Madrid, Spain
- Complutense University, Madrid, Spain
| | | | - Enrique Baquedano
- Institute of Evolution in Africa (IDEA), University of Alcalá, Madrid, Spain
- Regional Archaeological Museum of the Community of Madrid, Madrid, Spain
| | - Audax Mabulla
- University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Manuel Domínguez-Rodrigo
- Institute of Evolution in Africa (IDEA), University of Alcalá, Madrid, Spain
- Department of Anthropology, Rice University, Houston, TX, 77005-1827, USA
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5
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How Reliance on Allomaternal Care Shapes Primate Development with Special Reference to the Genus Homo. EVOLUTIONARY PSYCHOLOGY 2022. [DOI: 10.1007/978-3-030-76000-7_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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6
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Patalano R, Roberts P, Boivin N, Petraglia MD, Mercader J. Plant wax biomarkers in human evolutionary studies. Evol Anthropol 2021; 30:385-398. [PMID: 34369041 DOI: 10.1002/evan.21921] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 01/07/2021] [Accepted: 07/26/2021] [Indexed: 11/11/2022]
Abstract
Plant wax biomarkers are an innovative proxy for reconstructing vegetation composition and structure, rainfall intensity, temperature, and other climatic and environmental dynamics. Traditionally used in earth sciences and climate studies from "off-site" ocean and lake records, biomarker research is now incorporated in archeology and paleoanthropology to answer questions relating to past human-environment interactions and human evolution. Biomarker research is generating new and exciting information on the ecological context in which Homo and its closest relatives evolved, adapted, and invented stone tool technologies. In this review, we examine plant wax biomarkers and their use in reconstructing past plant landscapes and hydroclimates. We summarize the applications of plant wax molecular proxies in archeological research, assess challenges relating to taphonomy, consider the role of modern plant ecosystems in interpreting ancient habitats, and examine case studies conducted at key paleoanthropological locations in eastern and southern Africa and Europe.
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Affiliation(s)
- Robert Patalano
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany
| | - Patrick Roberts
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany.,School of Social Science, The University of Queensland, Brisbane, Australia.,Archaeological Studies Program, University of Philippines, Quezon City, Philippines
| | - Nicole Boivin
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany.,School of Social Science, The University of Queensland, Brisbane, Australia.,Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.,Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
| | - Michael D Petraglia
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany.,School of Social Science, The University of Queensland, Brisbane, Australia.,Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Julio Mercader
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany.,Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada.,Institut Català de Paleoecologia Humana i Evolució Social, Tarragona, Spain
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7
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Lupien RL, Russell JM, Subramanian A, Kinyanjui R, Beverly EJ, Uno KT, de Menocal P, Dommain R, Potts R. Eastern African environmental variation and its role in the evolution and cultural change of Homo over the last 1 million years. J Hum Evol 2021; 157:103028. [PMID: 34216947 DOI: 10.1016/j.jhevol.2021.103028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 05/20/2021] [Accepted: 05/20/2021] [Indexed: 10/21/2022]
Abstract
Characterizing eastern African environmental variability on orbital timescales is crucial to evaluating the hominin evolutionary response to past climate changes. However, there is a dearth of high-resolution, well-dated records of ecosystem dynamics from eastern Africa that cover long time intervals. In the last 1 Myr, there were significant anatomical and cultural developments in Homo, including the origin of Homo sapiens. There were also major changes in global climatic boundary conditions that may have affected eastern African environments, yet potential linkages remain poorly understood. We developed carbon isotopic records from plant waxes (δ13Cwax) and bulk organic matter (δ13COM) from a well-dated sediment core spanning the last ∼1 Myr extracted from the Koora Basin, located south of the Olorgesailie Basin, in the southern Kenya rift. Our record characterizes the climatic and environmental context for evolutionary events and technological advances recorded in the adjacent Olorgesailie Basin, such as the transition from Acheulean to Middle Stone Age tools by 320 ka. A significant shift toward more C4-dominated ecosystems and arid conditions occurred near the end of the mid-Pleistocene Transition, which indicates a link between equatorial eastern African and high-latitude northern hemisphere climate. Environmental variability increases throughout the mid- to late-Pleistocene, superimposed by precession-paced packets of variability modulated by eccentricity. An interval of particularly high-amplitude climate and environmental variability occurred from ∼275 ka to ∼180 ka, synchronous with evidence for the first H. sapiens fossils in eastern Africa. These results support the 'variability selection hypothesis' that increased environmental variability selected for adaptable traits, behaviors, and technology in our hominin ancestors.
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Affiliation(s)
- Rachel L Lupien
- Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02906, USA; Division of Biology and Paleo Environment, Lamont-Doherty Earth Observatory, Palisades, NY 10964, USA.
| | - James M Russell
- Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02906, USA
| | - Avinash Subramanian
- Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02906, USA
| | - Rahab Kinyanjui
- Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
| | - Emily J Beverly
- Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77204, USA
| | - Kevin T Uno
- Division of Biology and Paleo Environment, Lamont-Doherty Earth Observatory, Palisades, NY 10964, USA
| | - Peter de Menocal
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA; Division of Biology and Paleo Environment, Lamont-Doherty Earth Observatory, Palisades, NY 10964, USA
| | - René Dommain
- Institute of Geosciences, University of Potsdam, 14476 Potsdam, Germany; Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA
| | - Richard Potts
- Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA; Department of Earth Sciences, National Museums of Kenya, Nairobi 00100, Kenya
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8
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Stollhofen H, Stanistreet IG, Toth N, Schick KD, Rodríguez-Cintas A, Albert RM, Farrugia P, Njau JK, Pante MC, Herrmann EW, Ruck L, Bamford MK, Blumenschine RJ, Masao FT. Olduvai's oldest Oldowan. J Hum Evol 2020; 150:102910. [PMID: 33271475 DOI: 10.1016/j.jhevol.2020.102910] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/29/2020] [Accepted: 10/29/2020] [Indexed: 11/24/2022]
Abstract
Previously, Olduvai Bed I excavations revealed Oldowan assemblages <1.85 Ma, mainly in the eastern gorge. New western gorge excavations locate a much older ∼2.0 Ma assemblage between the Coarse Feldspar Crystal Tuff (∼2.015 Ma) and Tuff IA (∼1.98 Ma) of Lower Bed I, predating the oldest eastern gorge DK assemblage below Tuff IB by ∼150 kyr. We characterize this newly discovered fossil and artifact assemblage, adding information on landscape and hominin resource use during the ∼2.3-2.0 Ma period, scarce in Oldowan sites. Assemblage lithics and bones, lithofacies boundaries, and phytolith samples were surveyed and mapped. Sedimentological facies analysis, tephrostratigraphic and sequence stratigraphic principles were applied to reconstruct paleoenvironments and sedimentary processes of sandy claystone (lake), sandstone (fluvial), and sandy diamictite (debris flow) as principal lithofacies. Artifacts, sized, weighed, categorized, were examined for petrography, retouch, and flake scar size. Taxonomic classifications and taphonomic descriptions of faunal remains were made, and phytoliths were categorized based on reference collections. Lithics are dominantly quartzite, mainly debitage and less frequently simple cores, retouched pieces, and percussors. Well-rounded spheroids and retouched flakes are rare. Identifiable taxa, Ceratotherium cf. simum (white rhinoceros) and Equus cf. oldowayensis (extinct zebra), accord with nearby open savanna grasslands, inferred from C3 grass, mixed and/or alternating with C4 grass-dominated phytolith assemblages. Palms, sedges, and dicots were also identified from phytoliths. Diatoms and sponge spicules imply nearby freshwater. The assemblage accumulated at the toe of a Ngorongoro Volcano-sourced fan-delta apron of stacked debris flows, fluvials, and tuffs, preserving fossil tree stumps and wooded grassland phytoliths farther upfan. It formed after the climax of Ngorongoro volcanic activity during a Paleolake Olduvai lowstand and was then buried and preserved by lacustrine clays, marking the first of two lake transgressions, signifying wetter climates. Orbital precessional lake cycles were superposed upon multimillennial (∼4.9 kyr) lake fluctuations.
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Affiliation(s)
- Harald Stollhofen
- GeoZentrum Nordbayern, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Schlossgarten 5, 91054 Erlangen, Germany.
| | - Ian G Stanistreet
- Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Brownlow Street, Liverpool L69 3GP, UK; The Stone Age Institute, 1392 W. Dittemore Rd., Gosport, IN, 47433, USA
| | - Nicholas Toth
- The Stone Age Institute, 1392 W. Dittemore Rd., Gosport, IN, 47433, USA; Department of Anthropology, Indiana University, Bloomington, IN, 47405, USA; Department of Earth and Atmospheric Sciences, Indiana University, 1001 East 10th Street, Bloomington, IN, 47405-1405, USA
| | - Kathy D Schick
- The Stone Age Institute, 1392 W. Dittemore Rd., Gosport, IN, 47433, USA; Department of Anthropology, Indiana University, Bloomington, IN, 47405, USA; Department of Earth and Atmospheric Sciences, Indiana University, 1001 East 10th Street, Bloomington, IN, 47405-1405, USA
| | - Agata Rodríguez-Cintas
- ERAAUB, Department of History and Archaeology, Universitat de Barcelona, c/ Montalegre 6-8, 08001 Barcelona, Spain
| | - Rosa M Albert
- ERAAUB, Department of History and Archaeology, Universitat de Barcelona, c/ Montalegre 6-8, 08001 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluis Companys 23, 08010, Barcelona, Spain; Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, P Bag 3, WITS, 2050, South Africa
| | - Paul Farrugia
- Department of Earth and Atmospheric Sciences, Indiana University, 1001 East 10th Street, Bloomington, IN, 47405-1405, USA
| | - Jackson K Njau
- The Stone Age Institute, 1392 W. Dittemore Rd., Gosport, IN, 47433, USA; Department of Earth and Atmospheric Sciences, Indiana University, 1001 East 10th Street, Bloomington, IN, 47405-1405, USA
| | - Michael C Pante
- Department of Anthropology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Edward W Herrmann
- Department of Earth and Atmospheric Sciences, Indiana University, 1001 East 10th Street, Bloomington, IN, 47405-1405, USA
| | - Lana Ruck
- Department of Anthropology, Indiana University, Bloomington, IN, 47405, USA
| | - Marion K Bamford
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, P Bag 3, WITS, 2050, South Africa
| | - Robert J Blumenschine
- Paleontological Scientific Trust (PAST), P.O. Box 52379, Saxonwold, 2132, Johannesburg, South Africa
| | - Fidelis T Masao
- Archaeology Unit, Department of History, University of Dar Es Salaam, P.O. Box 35051, Dar Es Salaam, Tanzania
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9
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Sistiaga A, Husain F, Uribelarrea D, Martín-Perea DM, Ferland T, Freeman KH, Diez-Martín F, Baquedano E, Mabulla A, Domínguez-Rodrigo M, Summons RE. Microbial biomarkers reveal a hydrothermally active landscape at Olduvai Gorge at the dawn of the Acheulean, 1.7 Ma. Proc Natl Acad Sci U S A 2020; 117:24720-24728. [PMID: 32934140 PMCID: PMC7547214 DOI: 10.1073/pnas.2004532117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Landscape-scale reconstructions of ancient environments within the cradle of humanity may reveal insights into the relationship between early hominins and the changing resources around them. Many studies of Olduvai Gorge during Pliocene-Pleistocene times have revealed the presence of precession-driven wet-dry cycles atop a general aridification trend, though may underestimate the impact of local-scale conditions on early hominins, who likely experienced a varied and more dynamic landscape. Fossil lipid biomarkers from ancient plants and microbes encode information about their surroundings via their molecular structures and composition, and thus can shed light on past environments. Here, we employ fossil lipid biomarkers to study the paleolandscape at Olduvai Gorge at the emergence of the Acheulean technology, 1.7 Ma, through the Lower Augitic Sandstones layer. In the context of the expansion of savanna grasslands, our results represent a resource-rich mosaic ecosystem populated by groundwater-fed rivers, aquatic plants, angiosperm shrublands, and edible plants. Evidence of a geothermally active landscape is reported via an unusual biomarker distribution consistent with the presence of hydrothermal features seen today at Yellowstone National Park. The study of hydrothermalism in ancient settings and its impact on hominin evolution has not been addressed before, although the association of thermal springs in the proximity of archaeological sites documented here can also be found at other localities. The hydrothermal features and resources present at Olduvai Gorge may have allowed early hominins to thermally process edible plants and meat, supporting the possibility of a prefire stage of human evolution.
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Affiliation(s)
- Ainara Sistiaga
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139;
- GLOBE Institute, University of Copenhagen, 1350 Copenhagen, Denmark
| | - Fatima Husain
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - David Uribelarrea
- Institute of Evolution in Africa (IDEA), University of Alcalá, 28010, Madrid, Spain
- Geodynamics, Stratigraphy and Palaeontology Department, Complutense University of Madrid, 28040 Madrid, Spain
| | - David M Martín-Perea
- Institute of Evolution in Africa (IDEA), University of Alcalá, 28010, Madrid, Spain
- Geodynamics, Stratigraphy and Palaeontology Department, Complutense University of Madrid, 28040 Madrid, Spain
- Paleobiology Department, National Natural Sciences Museum, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain
| | - Troy Ferland
- Department of Geosciences, The Pennsylvania State University, University Park, PA 16802
| | - Katherine H Freeman
- Department of Geosciences, The Pennsylvania State University, University Park, PA 16802
| | - Fernando Diez-Martín
- Department of Prehistory and Archaeology, Universidad de Valladolid, 47002 Valladolid, Spain
| | | | - Audax Mabulla
- Department of Archaeology and Heritage Studies, University of Dar es Salaam, 35050 Dar es Salaam, Tanzania
| | - Manuel Domínguez-Rodrigo
- Institute of Evolution in Africa (IDEA), University of Alcalá, 28010, Madrid, Spain
- Department of Philosophy and History (Area of Prehistory), University of Alcalá, 28801 Alcalá de Henares, Spain
| | - Roger E Summons
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
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10
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Patalano R, Zech J, Roberts P. Leaf Wax Lipid Extraction for Archaeological Applications. ACTA ACUST UNITED AC 2020; 5:e20114. [DOI: 10.1002/cppb.20114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Robert Patalano
- Department of Archaeology Max Planck Institute for the Science of Human History Jena Germany
| | - Jana Zech
- Department of Archaeology Max Planck Institute for the Science of Human History Jena Germany
| | - Patrick Roberts
- Department of Archaeology Max Planck Institute for the Science of Human History Jena Germany
- School of Social Science The University of Queensland Brisbane Australia
- Archaeological Studies Program University of Philippines, Diliman, Quenzon City Philippines
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11
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Savanna tree evolutionary ages inform the reconstruction of the paleoenvironment of our hominin ancestors. Sci Rep 2020; 10:12430. [PMID: 32709951 PMCID: PMC7381606 DOI: 10.1038/s41598-020-69378-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 03/31/2020] [Indexed: 11/24/2022] Open
Abstract
Ideas on hominin evolution have long invoked the emergence from forests into open habitats as generating selection for traits such as bipedalism and dietary shifts. Though controversial, the savanna hypothesis continues to motivate research into the palaeo-environments of Africa. Reconstruction of these ancient environments has depended heavily on carbon isotopic analysis of fossil bones and palaeosols. The sparsity of the fossil record, however, imposes a limit to the strength of inference that can be drawn from such data. Time-calibrated phylogenies offer an additional tool for dating the spread of savanna habitat. Here, using the evolutionary ages of African savanna trees, we suggest an initial tropical or subtropical expansion of savanna between 10 and 15 Ma, which then extended to higher latitudes, reaching southern Africa ca. 3 Ma. Our phylogenetic estimates of the origin and latitudinal spread of savannas broadly correspond with isotopic age estimates and encompass the entire hominin fossil record. Our results are consistent with the savanna hypothesis of early hominin evolution and reignite the debate on the drivers of savanna expansion. Our analysis demonstrates the utility of phylogenetic proxies for dating major ecological transitions in geological time, especially in regions where fossils are rare or absent or occur in discontinuous sediments.
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12
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Hrdy SB, Burkart JM. The emergence of emotionally modern humans: implications for language and learning. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190499. [PMID: 32475330 PMCID: PMC7293152 DOI: 10.1098/rstb.2019.0499] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
According to the Cooperative Breeding Hypothesis, apes with the life-history attributes of those in the line leading to the genus Homo could not have evolved unless male and female allomothers had begun to help mothers care for and provision offspring. As proposed elsewhere, the unusual way hominins reared their young generated novel phenotypes subsequently subjected to Darwinian social selection favouring those young apes best at monitoring the intentions, mental states and preferences of others and most motivated to attract and appeal to caretakers. Not only were youngsters acquiring information in social contexts different from those of other apes, but they would also have been emotionally and neurophysiologically different from them in ways that are relevant to how humans learn. Contingently delivered rewards to dependents who attracted and ingratiated themselves with allomothers shaped their behaviours and vocalizations and transformed the way developing youngsters learned from others and internalized their preferences. This article is part of the theme issue 'Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals'.
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Affiliation(s)
| | - Judith M Burkart
- Department of Anthropology, University of Zurich, Winterthurerstrasse 190, 8051 Zurich, Switzerland
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13
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Mercader J, Clarke S, Bundala M, Favreau J, Inwood J, Itambu M, Larter F, Lee P, Lewiski-McQuaid G, Mollel N, Mwambwiga A, Patalano R, Soto M, Tucker L, Walde D. Soil and plant phytoliths from the Acacia-Commiphora mosaics at Oldupai Gorge (Tanzania). PeerJ 2019; 7:e8211. [PMID: 31844589 PMCID: PMC6911344 DOI: 10.7717/peerj.8211] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 11/14/2019] [Indexed: 11/20/2022] Open
Abstract
This article studies soil and plant phytoliths from the Eastern Serengeti Plains, specifically the Acacia-Commiphora mosaics from Oldupai Gorge, Tanzania, as present-day analogue for the environment that was contemporaneous with the emergence of the genus Homo. We investigate whether phytolith assemblages from recent soil surfaces reflect plant community structure and composition with fidelity. The materials included 35 topsoil samples and 29 plant species (20 genera, 15 families). Phytoliths were extracted from both soil and botanical samples. Quantification aimed at discovering relationships amongst the soil and plant phytoliths relative distributions through Chi-square independence tests, establishing the statistical significance of the relationship between categorical variables within the two populations. Soil assemblages form a spectrum, or cohort of co-ocurring phytolith classes, that will allow identifying environments similar to those in the Acacia-Commiphora ecozone in the fossil record.
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Affiliation(s)
- Julio Mercader
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany
| | - Siobhán Clarke
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
| | - Mariam Bundala
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
- Department of Archaeology and Heritage Studies, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Julien Favreau
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
| | - Jamie Inwood
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
| | - Makarius Itambu
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
- Department of Archaeology and Heritage Studies, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Fergus Larter
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
| | - Patrick Lee
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
- Department of Anthropology, University of Toronto, Toronto, Canada
| | | | - Neduvoto Mollel
- Tropical Pesticides Research Institute, National Herbarium of Tanzania, Arusha, Tanzania
| | - Aloyce Mwambwiga
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
- Arusha National Natural History Museum, Arusha, Tanzania
| | - Robert Patalano
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
| | - María Soto
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
| | - Laura Tucker
- Department of Anthropology and Archaeology, University of Calgary, Calgary, Canada
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14
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Magill CR, Eglinton G, Eglinton TI. Isotopic variance among plant lipid homologues correlates with biodiversity patterns of their source communities. PLoS One 2019; 14:e0212211. [PMID: 30811453 PMCID: PMC6392421 DOI: 10.1371/journal.pone.0212211] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 01/29/2019] [Indexed: 11/18/2022] Open
Abstract
Plant diversity is important to human welfare worldwide, and this importance is exemplified in subtropical and tropical [(sub)tropical] African savannahs where regional biodiversity enhances the sustaining provision of basic ecosystem services available to millions of residents. Yet, there is a critical lack of knowledge about how savannahs respond to climate change. Here, we report the relationships between savannah vegetation structure, species richness, and bioclimatic variables as recorded by plant biochemical fossils, called biomarkers. Our analyses reveal that the stable carbon isotope composition (δ13C) of discrete sedimentary plant biomarkers reflects vegetation structure, but the isotopic range among plant biomarkers–which we call LEaf Wax Isotopic Spread (LEWIS)–reflects species richness. Analyses of individual biomarker δ13C values and LEWIS for downcore sediments recovered from southeast Africa reveal that the region’s species richness mirrored trends in atmospheric carbon dioxide concentration (pCO2) throughout the last 25,000 years. This suggests that increasing pCO2 levels during post-industrialization may prompt future declines in regional biodiversity (1–10 species per unit CO2 p.p.m.v.) through imminent habitat loss or extinction.
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Affiliation(s)
- Clayton R. Magill
- Lyell Centre, Heriot-Watt University, Edinburgh, United Kingdom
- Geological Institute, ETH Zürich, Zurich, Switzerland
- * E-mail:
| | - Geoffrey Eglinton
- Department of Earth Sciences, University of Bristol, Bristol, United Kingdom
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15
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Stanistreet IG, McHenry LJ, Stollhofen H, de la Torre I. Bed II Sequence Stratigraphic context of EF-HR and HWK EE archaeological sites, and the Oldowan/Acheulean succession at Olduvai Gorge, Tanzania. J Hum Evol 2018; 120:19-31. [DOI: 10.1016/j.jhevol.2018.01.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 01/05/2018] [Accepted: 01/26/2018] [Indexed: 11/15/2022]
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16
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Uno KT, Rivals F, Bibi F, Pante M, Njau J, de la Torre I. Large mammal diets and paleoecology across the Oldowan–Acheulean transition at Olduvai Gorge, Tanzania from stable isotope and tooth wear analyses. J Hum Evol 2018; 120:76-91. [DOI: 10.1016/j.jhevol.2018.01.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 12/27/2017] [Accepted: 01/02/2018] [Indexed: 11/27/2022]
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17
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Distinctions in heterotrophic and autotrophic-based metabolism as recorded in the hydrogen and carbon isotope ratios of normal alkanes. Oecologia 2018; 187:1053-1075. [DOI: 10.1007/s00442-018-4189-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 06/05/2018] [Indexed: 10/28/2022]
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18
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Bonnefille R, Melis RT, Mussi M. Variability in the Mountain Environment at Melka Kunture Archaeological Site, Ethiopia, During the Early Pleistocene (~1.7 Ma) and the Mid-Pleistocene Transition (0.9–0.6 Ma). VERTEBRATE PALEOBIOLOGY AND PALEOANTHROPOLOGY 2018. [DOI: 10.1007/978-3-319-75985-2_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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19
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Linder HP. East African Cenozoic vegetation history. Evol Anthropol 2017; 26:300-312. [DOI: 10.1002/evan.21570] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Hans Peter Linder
- Institute of Systematic and Evolutionary Botany; University of Zurich; Zollikerstrasse Switzerland
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20
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Abstract
Aridification is often considered a major driver of long-term ecological change and hominin evolution in eastern Africa during the Plio-Pleistocene; however, this hypothesis remains inadequately tested owing to difficulties in reconstructing terrestrial paleoclimate. We present a revised aridity index for quantifying water deficit (WD) in terrestrial environments using tooth enamel δ18O values, and use this approach to address paleoaridity over the past 4.4 million years in eastern Africa. We find no long-term trend in WD, consistent with other terrestrial climate indicators in the Omo-Turkana Basin, and no relationship between paleoaridity and herbivore paleodiet structure among fossil collections meeting the criteria for WD estimation. Thus, we suggest that changes in the abundance of C4 grass and grazing herbivores in eastern Africa during the Pliocene and Pleistocene may have been decoupled from aridity. As in modern African ecosystems, other factors, such as rainfall seasonality or ecological interactions among plants and mammals, may be important for understanding the evolution of C4 grass- and grazer-dominated biomes.
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21
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Abstract
Members of genus Homo are the only animals known to create and control fire. The adaptive significance of this unique behavior is broadly recognized, but the steps by which our ancestors evolved pyrotechnic abilities remain unknown. Many hypotheses attempting to answer this question attribute hominin fire to serendipitous, even accidental, discovery. Using recent paleoenvironmental reconstructions, we present an alternative scenario in which, 2 to 3 million years ago in tropical Africa, human fire dependence was the result of adapting to progressively fire-prone environments. The extreme and rapid fluctuations between closed canopy forests, woodland, and grasslands that occurred in tropical Africa during that time, in conjunction with reductions in atmospheric carbon dioxide levels, changed the fire regime of the region, increasing the occurrence of natural fires. We use models from optimal foraging theory to hypothesize benefits that this fire-altered landscape provided to ancestral hominins and link these benefits to steps that transformed our ancestors into a genus of active pyrophiles whose dependence on fire for survival contributed to its rapid expansion out of Africa.
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22
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Johnson TC, Werne JP, Brown ET, Abbott A, Berke M, Steinman BA, Halbur J, Contreras S, Grosshuesch S, Deino A, Scholz CA, Lyons RP, Schouten S, Damsté JSS. A progressively wetter climate in southern East Africa over the past 1.3 million years. Nature 2016; 537:220-224. [PMID: 27509851 DOI: 10.1038/nature19065] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 06/28/2016] [Indexed: 11/09/2022]
Abstract
African climate is generally considered to have evolved towards progressively drier conditions over the past few million years, with increased variability as glacial-interglacial change intensified worldwide. Palaeoclimate records derived mainly from northern Africa exhibit a 100,000-year (eccentricity) cycle overprinted on a pronounced 20,000-year (precession) beat, driven by orbital forcing of summer insolation, global ice volume and long-lived atmospheric greenhouse gases. Here we present a 1.3-million-year-long climate history from the Lake Malawi basin (10°-14° S in eastern Africa), which displays strong 100,000-year (eccentricity) cycles of temperature and rainfall following the Mid-Pleistocene Transition around 900,000 years ago. Interglacial periods were relatively warm and moist, while ice ages were cool and dry. The Malawi record shows limited evidence for precessional variability, which we attribute to the opposing effects of austral summer insolation and the temporal/spatial pattern of sea surface temperature in the Indian Ocean. The temperature history of the Malawi basin, at least for the past 500,000 years, strongly resembles past changes in atmospheric carbon dioxide and terrigenous dust flux in the tropical Pacific Ocean, but not in global ice volume. Climate in this sector of eastern Africa (unlike northern Africa) evolved from a predominantly arid environment with high-frequency variability to generally wetter conditions with more prolonged wet and dry intervals.
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Affiliation(s)
- T C Johnson
- Large Lakes Observatory and Department of Earth and Environmental Sciences, University of Minnesota Duluth, Duluth, Minnesota 55812, USA.,Department of Geosciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
| | - J P Werne
- Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - E T Brown
- Large Lakes Observatory and Department of Earth and Environmental Sciences, University of Minnesota Duluth, Duluth, Minnesota 55812, USA
| | - A Abbott
- Department of Earth and Planetary Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales 2109, Australia
| | - M Berke
- Department of Civil &Environmental Engineering &Earth Sciences, University of Notre Dame, 257 Fitzpatrick Hall, Notre Dame, Indiana 46556, USA
| | - B A Steinman
- Large Lakes Observatory and Department of Earth and Environmental Sciences, University of Minnesota Duluth, Duluth, Minnesota 55812, USA
| | - J Halbur
- Large Lakes Observatory and Department of Earth and Environmental Sciences, University of Minnesota Duluth, Duluth, Minnesota 55812, USA
| | - S Contreras
- Departamento de Química Ambiental and Centro de Investigación en Biodiversidad y Ambientes Sustentables (CIBAS), Universidad Católica de la Santísima Concepción, Casilla 297, Concepción, Chile
| | - S Grosshuesch
- Large Lakes Observatory and Department of Earth and Environmental Sciences, University of Minnesota Duluth, Duluth, Minnesota 55812, USA
| | - A Deino
- Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA
| | - C A Scholz
- Earth Sciences Department, Syracuse University, 011a Heroy Geology Laboratory, Syracuse, New York 13244, USA
| | - R P Lyons
- Earth Sciences Department, Syracuse University, 011a Heroy Geology Laboratory, Syracuse, New York 13244, USA
| | - S Schouten
- NIOZ Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, PO Box 59, 1790 AB Den Burg, The Netherlands.,Faculty of Geosciences, Department of Earth Sciences, Utrecht University, PO Box 80.021, 3508 TA Utrecht, The Netherlands
| | - J S Sinninghe Damsté
- NIOZ Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, PO Box 59, 1790 AB Den Burg, The Netherlands.,Faculty of Geosciences, Department of Earth Sciences, Utrecht University, PO Box 80.021, 3508 TA Utrecht, The Netherlands
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23
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Uno KT, Polissar PJ, Kahle E, Feibel C, Harmand S, Roche H, deMenocal PB. A Pleistocene palaeovegetation record from plant wax biomarkers from the Nachukui Formation, West Turkana, Kenya. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150235. [PMID: 27298466 PMCID: PMC4920292 DOI: 10.1098/rstb.2015.0235] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2016] [Indexed: 11/12/2022] Open
Abstract
Reconstructing vegetation at hominin fossil sites provides us critical information about hominin palaeoenvironments and the potential role of climate in their evolution. Here we reconstruct vegetation from carbon isotopes of plant wax biomarkers in sediments of the Nachukui Formation in the Turkana Basin. Plant wax biomarkers were extracted from samples from a wide range of lithologies that include fluvial-lacustrine sediments and palaeosols, and therefore provide a record of vegetation from diverse depositional environments. Carbon isotope ratios from biomarkers indicate a highly dynamic vegetation structure (ca 5-100% C4 vegetation) from 2.3 to 1.7 Ma, with an overall shift towards more C4 vegetation on the landscape after about 2.1 Ma. The biomarker isotope data indicate ca 25-30% more C4 vegetation on the landscape than carbon isotope data of pedogenic carbonates from the same sequence. Our data show that the environments of early Paranthropus and Homo in this part of the Turkana Basin were primarily mixed C3-C4 to C4-dominated ecosystems. The proportion of C4-based foods in the diet of Paranthropus increases through time, broadly paralleling the increase in C4 vegetation on the landscape, whereas the diet of Homo remains unchanged. Biomarker isotope data associated with the Kokiselei archaeological site complex, which includes the site where the oldest Acheulean stone tools to date were recovered, indicate 61-97% C4 vegetation on the landscape.This article is part of the themed issue 'Major transitions in human evolution'.
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Affiliation(s)
- Kevin T Uno
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
| | - Pratigya J Polissar
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
| | - Emma Kahle
- Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA
| | - Craig Feibel
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA Department of Anthropology, Rutgers University, Piscataway, NJ 08854, USA
| | - Sonia Harmand
- Turkana Basin Institute, Stony Brook University, Stony Brook, NY 11794, USA CNRS, UMR 7055, Maison de l'Archéologie et de l'Ethnologie, Université Paris Ouest-Nanterre La Défense, Nanterre, Cedex 92023, France
| | - Hélène Roche
- CNRS, UMR 7055, Maison de l'Archéologie et de l'Ethnologie, Université Paris Ouest-Nanterre La Défense, Nanterre, Cedex 92023, France
| | - Peter B deMenocal
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA
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24
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Rose C, Polissar PJ, Tierney JE, Filley T, deMenocal PB. Changes in northeast African hydrology and vegetation associated with Pliocene-Pleistocene sapropel cycles. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150243. [PMID: 27298473 PMCID: PMC4920299 DOI: 10.1098/rstb.2015.0243] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2016] [Indexed: 11/12/2022] Open
Abstract
East African climate change since the Late Miocene consisted of persistent shorter-term, orbital-scale wet-dry cycles superimposed upon a long-term trend towards more open, grassy landscapes. Either or both of these modes of palaeoclimate variability may have influenced East African mammalian evolution, yet the interrelationship between these secular and orbital palaeoclimate signals remains poorly understood. Here, we explore whether the long-term secular climate change was also accompanied by significant changes at the orbital-scale. We develop northeast African hydroclimate and vegetation proxy data for two 100 kyr-duration windows near 3.05 and 1.75 Ma at ODP Site 967 in the eastern Mediterranean basin, where sedimentation is dominated by eastern Sahara dust input and Nile River run-off. These two windows were selected because they have comparable orbital configurations and bracket an important increase in East African C4 grasslands. We conducted high-resolution (2.5 kyr sampling) multiproxy biomarker, H- and C-isotopic analyses of plant waxes and lignin phenols to document orbital-scale changes in hydrology, vegetation and woody cover for these two intervals. Both intervals are dominated by large-amplitude, precession-scale (approx. 20 kyr) changes in northeast African vegetation and rainfall/run-off. The δ(13)Cwax values and lignin phenol composition record a variable but consistently C4 grass-dominated ecosystem for both intervals (50-80% C4). Precessional δDwax cycles were approximately 20-30‰ in peak-to-peak amplitude, comparable with other δDwax records of the Early Holocene African Humid Period. There were no significant differences in the means or variances of the δDwax or δ(13)Cwax data for the 3.05 and 1.75 Ma intervals studied, suggesting that the palaeohydrology and palaeovegetation responses to precessional forcing were similar for these two periods. Data for these two windows suggest that the eastern Sahara did not experience the significant increase in C4 vegetation that has been observed in East Africa over this time period. This observation would be consistent with a proposed mechanism whereby East African precipitation is reduced, and drier conditions established, in response to the emergence of modern zonal sea surface temperature gradients in the tropical oceans between 3 and 2 Ma.This article is part of the themed issue 'Major transitions in human evolution'.
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Affiliation(s)
- Cassaundra Rose
- Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA
| | - Pratigya J Polissar
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
| | - Jessica E Tierney
- Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA
| | - Timothy Filley
- Department of Earth and Atmospheric Sciences, The Purdue Climate Change Research Center, Purdue University, West Lafayette, IN 47907, USA
| | - Peter B deMenocal
- Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
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25
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Uno KT, Polissar PJ, Jackson KE, deMenocal PB. Neogene biomarker record of vegetation change in eastern Africa. Proc Natl Acad Sci U S A 2016; 113:6355-63. [PMID: 27274042 PMCID: PMC4988583 DOI: 10.1073/pnas.1521267113] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The evolution of C4 grassland ecosystems in eastern Africa has been intensely studied because of the potential influence of vegetation on mammalian evolution, including that of our own lineage, hominins. Although a handful of sparse vegetation records exists from middle and early Miocene terrestrial fossil sites, there is no comprehensive record of vegetation through the Neogene. Here we present a vegetation record spanning the Neogene and Quaternary Periods that documents the appearance and subsequent expansion of C4 grasslands in eastern Africa. Carbon isotope ratios from terrestrial plant wax biomarkers deposited in marine sediments indicate constant C3 vegetation from ∼24 Ma to 10 Ma, when C4 grasses first appeared. From this time forward, C4 vegetation increases monotonically to present, with a coherent signal between marine core sites located in the Somali Basin and the Red Sea. The response of mammalian herbivores to the appearance of C4 grasses at 10 Ma is immediate, as evidenced from existing records of mammalian diets from isotopic analyses of tooth enamel. The expansion of C4 vegetation in eastern Africa is broadly mirrored by increasing proportions of C4-based foods in hominin diets, beginning at 3.8 Ma in Australopithecus and, slightly later, Kenyanthropus This continues into the late Pleistocene in Paranthropus, whereas Homo maintains a flexible diet. The biomarker vegetation record suggests the increase in open, C4 grassland ecosystems over the last 10 Ma may have operated as a selection pressure for traits and behaviors in Homo such as bipedalism, flexible diets, and complex social structure.
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Affiliation(s)
- Kevin T Uno
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964;
| | - Pratigya J Polissar
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964
| | - Kevin E Jackson
- Department of Geology and Environmental Geosciences, Lafayette College, Easton, PA 18042
| | - Peter B deMenocal
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964; Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027
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26
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Hrdy SB. Variable postpartum responsiveness among humans and other primates with "cooperative breeding": A comparative and evolutionary perspective. Horm Behav 2016; 77:272-83. [PMID: 26518662 DOI: 10.1016/j.yhbeh.2015.10.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/21/2015] [Accepted: 10/26/2015] [Indexed: 11/26/2022]
Abstract
This article is part of a Special Issue "Parental Care".Until recently, evolutionists reconstructing mother-infant bonding among human ancestors relied on nonhuman primate models characterized by exclusively maternal care, overlooking the highly variable responsiveness exhibited by mothers in species with obligate reliance on allomaternal care and provisioning. It is now increasingly recognized that apes as large-brained, slow maturing, and nutritionally dependent for so long as early humans were, could not have evolved unless "alloparents" (group members other than genetic parents), in addition to parents, had helped mothers to care for and provision offspring, a rearing system known as "cooperative breeding." Here I review situation-dependent maternal responses ranging from highly possessive to permissive, temporarily distancing, rejecting, or infanticidal, documented for a small subset of cooperatively breeding primates. As in many mammals, primate maternal responsiveness is influenced by physical condition, endocrinological priming, prior experience and local environments (especially related to security). But mothers among primates who evolved as cooperative breeders also appear unusually sensitive to cues of social support. In addition to more "sapient" or rational decision-making, humankind's deep history of cooperative breeding must be considered when trying to understand the extremely variable responsiveness of human mothers.
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Affiliation(s)
- Sarah B Hrdy
- Citrona Farms, 21440 County Road 87, Winters, CA 95694, USA.
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27
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Lüdecke T, Schrenk F, Thiemeyer H, Kullmer O, Bromage TG, Sandrock O, Fiebig J, Mulch A. Persistent C3 vegetation accompanied Plio-Pleistocene hominin evolution in the Malawi Rift (Chiwondo Beds, Malawi). J Hum Evol 2016; 90:163-75. [DOI: 10.1016/j.jhevol.2015.10.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 10/22/2022]
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Maslin MA, Shultz S, Trauth MH. A synthesis of the theories and concepts of early human evolution. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140064. [PMID: 25602068 PMCID: PMC4305165 DOI: 10.1098/rstb.2014.0064] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Current evidence suggests that many of the major events in hominin evolution occurred in East Africa. Hence, over the past two decades, there has been intensive work undertaken to understand African palaeoclimate and tectonics in order to put together a coherent picture of how the environment of Africa has varied over the past 10 Myr. A new consensus is emerging that suggests the unusual geology and climate of East Africa created a complex, environmentally very variable setting. This new understanding of East African climate has led to the pulsed climate variability hypothesis that suggests the long-term drying trend in East Africa was punctuated by episodes of short alternating periods of extreme humidity and aridity which may have driven hominin speciation, encephalization and dispersals out of Africa. This hypothesis is unique as it provides a conceptual framework within which other evolutionary theories can be examined: first, at macro-scale comparing phylogenetic gradualism and punctuated equilibrium; second, at a more focused level of human evolution comparing allopatric speciation, aridity hypothesis, turnover pulse hypothesis, variability selection hypothesis, Red Queen hypothesis and sympatric speciation based on sexual selection. It is proposed that each one of these mechanisms may have been acting on hominins during these short periods of climate variability, which then produce a range of different traits that led to the emergence of new species. In the case of Homo erectus (sensu lato), it is not just brain size that changes but life history (shortened inter-birth intervals, delayed development), body size and dimorphism, shoulder morphology to allow thrown projectiles, adaptation to long-distance running, ecological flexibility and social behaviour. The future of evolutionary research should be to create evidence-based meta-narratives, which encompass multiple mechanisms that select for different traits leading ultimately to speciation.
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Affiliation(s)
- Mark A Maslin
- Department of Geography, University College London, Pearson Building, Gower Street, London, UK
| | - Susanne Shultz
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Martin H Trauth
- University of Potsdam, Institute of Earth and Environmental Science, Karl-Liebknecht-Street 24-25, Potsdam 14476, Germany
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Stewart KM. Environmental change and hominin exploitation of C4-based resources in wetland/savanna mosaics. J Hum Evol 2014; 77:1-16. [DOI: 10.1016/j.jhevol.2014.10.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Revised: 03/05/2014] [Accepted: 10/06/2014] [Indexed: 10/24/2022]
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Cuthbert MO, Ashley GM. A spring forward for hominin evolution in East Africa. PLoS One 2014; 9:e107358. [PMID: 25207544 PMCID: PMC4160244 DOI: 10.1371/journal.pone.0107358] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/15/2014] [Indexed: 11/18/2022] Open
Abstract
Groundwater is essential to modern human survival during drought periods. There is also growing geological evidence of springs associated with stone tools and hominin fossils in the East African Rift System (EARS) during a critical period for hominin evolution (from 1.8 Ma). However it is not known how vulnerable these springs may have been to climate variability and whether groundwater availability may have played a part in human evolution. Recent interdisciplinary research at Olduvai Gorge, Tanzania, has documented climate fluctuations attributable to astronomic forcing and the presence of paleosprings directly associated with archaeological sites. Using palaeogeological reconstruction and groundwater modelling of the Olduvai Gorge paleo-catchment, we show how spring discharge was likely linked to East African climate variability of annual to Milankovitch cycle timescales. Under decadal to centennial timescales, spring flow would have been relatively invariant providing good water resource resilience through long droughts. For multi-millennial periods, modelled spring flows lag groundwater recharge by 100 s to 1000 years. The lag creates long buffer periods allowing hominins to adapt to new habitats as potable surface water from rivers or lakes became increasingly scarce. Localised groundwater systems are likely to have been widespread within the EARS providing refugia and intense competition during dry periods, thus being an important factor in natural selection and evolution, as well as a vital resource during hominin dispersal within and out of Africa.
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Affiliation(s)
- Mark O. Cuthbert
- Connected Waters Initiative Research Centre, UNSW Australia, Sydney, NSW, Australia
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
- * E-mail:
| | - Gail M. Ashley
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey, United States of America
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Galván B, Hernández CM, Mallol C, Mercier N, Sistiaga A, Soler V. New evidence of early Neanderthal disappearance in the Iberian Peninsula. J Hum Evol 2014; 75:16-27. [PMID: 25016565 DOI: 10.1016/j.jhevol.2014.06.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 05/27/2014] [Accepted: 06/09/2014] [Indexed: 10/25/2022]
Abstract
The timing of the end of the Middle Palaeolithic and the disappearance of Neanderthals continue to be strongly debated. Current chronometric evidence from different European sites pushes the end of the Middle Palaeolithic throughout the continent back to around 42 thousand years ago (ka). This has called into question some of the dates from the Iberian Peninsula, previously considered as one of the last refuge zones of the Neanderthals. Evidence of Neanderthal occupation in Iberia after 42 ka is now very scarce and open to debate on chronological and technological grounds. Here we report thermoluminescence (TL) and optically stimulated luminescence (OSL) dates from El Salt, a Middle Palaeolithic site in Alicante, Spain, the archaeological sequence of which shows a transition from recurrent to sporadic human occupation culminating in the abandonment of the site. The new dates place this sequence within MIS 3, between ca. 60 and 45 ka. An abrupt sedimentary change towards the top of the sequence suggests a strong aridification episode coinciding with the last Neanderthal occupation of the site. These results are in agreement with current chronometric data from other sites in the Iberian Peninsula and point towards possible breakdown and disappearance of the Neanderthal local population around the time of the Heinrich 5 event. Iberian sites with recent dates (<40 ka) attributed to the Middle Palaeolithic should be revised in the light of these data.
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Affiliation(s)
- Bertila Galván
- U.D.I. de Prehistoria, Arqueología e Historia Antigua, Facultad de Geografía e Historia, Universidad de La Laguna, Campus de Guajara, 38071 La Laguna, Santa Cruz de Tenerife, Spain
| | - Cristo M Hernández
- U.D.I. de Prehistoria, Arqueología e Historia Antigua, Facultad de Geografía e Historia, Universidad de La Laguna, Campus de Guajara, 38071 La Laguna, Santa Cruz de Tenerife, Spain.
| | - Carolina Mallol
- U.D.I. de Prehistoria, Arqueología e Historia Antigua, Facultad de Geografía e Historia, Universidad de La Laguna, Campus de Guajara, 38071 La Laguna, Santa Cruz de Tenerife, Spain; Instituto Universitario de Biorgánica Antonio González, Av. Astrofísico Francisco Sánchez n.° 2, 38206 La Laguna, Tenerife, Spain
| | - Norbert Mercier
- Institut de Recherche sur les Archéomatériaux, UMR 5060 CNRS-Université de Bordeaux, Centre de Recherche en PhysiqueAppliquée à l'Archéologie (CRP2A), Maison de l'Archéologie, 33607 PESSAC Cedex, France
| | - Ainara Sistiaga
- U.D.I. de Prehistoria, Arqueología e Historia Antigua, Facultad de Geografía e Historia, Universidad de La Laguna, Campus de Guajara, 38071 La Laguna, Santa Cruz de Tenerife, Spain; Instituto Universitario de Biorgánica Antonio González, Av. Astrofísico Francisco Sánchez n.° 2, 38206 La Laguna, Tenerife, Spain
| | - Vicente Soler
- Estación Volcanológica de Canarias, IPNA-CSIC, Av. Astrofísico Francisco Sánchez n.° 3, 38206 La Laguna, Tenerife, Spain
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Domínguez-Rodrigo M. Is the “Savanna Hypothesis” a Dead Concept for Explaining the Emergence of the Earliest Hominins? CURRENT ANTHROPOLOGY 2014. [DOI: 10.1086/674530] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Shultz S, Maslin M. Early human speciation, brain expansion and dispersal influenced by African climate pulses. PLoS One 2013; 8:e76750. [PMID: 24146922 PMCID: PMC3797764 DOI: 10.1371/journal.pone.0076750] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 08/28/2013] [Indexed: 12/02/2022] Open
Abstract
Early human evolution is characterised by pulsed speciation and dispersal events that cannot be explained fully by global or continental paleoclimate records. We propose that the collated record of ephemeral East African Rift System (EARS) lakes could be a proxy for the regional paleoclimate conditions experienced by early hominins. Here we show that the presence of these lakes is associated with low levels of dust deposition in both West African and Mediterranean records, but is not associated with long-term global cooling and aridification of East Africa. Hominin expansion and diversification seem to be associated with climate pulses characterized by the precession-forced appearance and disappearance of deep EARS lakes. The most profound period for hominin evolution occurs at about 1.9 Ma; with the highest recorded diversity of hominin species, the appearance of Homo (sensu stricto) and major dispersal events out of East Africa into Eurasia. During this period, ephemeral deep-freshwater lakes appeared along the whole length of the EARS, fundamentally changing the local environment. The relationship between the local environment and hominin brain expansion is less clear. The major step-wise expansion in brain size around 1.9 Ma when Homo appeared was coeval with the occurrence of ephemeral deep lakes. Subsequent incremental increases in brain size are associated with dry periods with few if any lakes. Plio-Pleistocene East African climate pulses as evinced by the paleo-lake records seem, therefore, fundamental to hominin speciation, encephalisation and migration.
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Affiliation(s)
- Susanne Shultz
- Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
| | - Mark Maslin
- Department of Geography, University College London, London, United Kingdom
- * E-mail:
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Sustainable Complex Triangular Cells for the Evaluation of CO2 Emissions by Individuals instead of Nations in a Scenario for 2030. SUSTAINABILITY 2013. [DOI: 10.3390/su5051944] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Capturing climate variability during our ancestors' earliest days. Proc Natl Acad Sci U S A 2013; 110:1144-5. [PMID: 23307813 DOI: 10.1073/pnas.1220747110] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
Water and its influence on plants likely exerted strong adaptive pressures in human evolution. Understanding relationships among water, plants, and early humans is limited both by incomplete terrestrial records of environmental change and by indirect proxy data for water availability. Here we present a continuous record of stable hydrogen-isotope compositions (expressed as δD values) for lipid biomarkers preserved in lake sediments from an early Pleistocene archaeological site in eastern Africa--Olduvai Gorge. We convert sedimentary leaf- and algal-lipid δD values into estimates for ancient source-water δD values by accounting for biochemical, physiological, and environmental influences on isotopic fractionation via published water-lipid enrichment factors for living plants, algae, and recent sediments. Reconstructed precipitation and lake-water δD values, respectively, are consistent with modern isotopic hydrology and reveal that dramatic fluctuations in water availability accompanied ecosystem changes. Drier conditions, indicated by less negative δD values, occur in association with stable carbon-isotopic evidence for open, C(4)-dominated grassland ecosystems. Wetter conditions, indicated by lower δD values, are associated with expanded woody cover across the ancient landscape. Estimates for ancient precipitation amounts, based on reconstructed precipitation δD values, range between approximately 250 and 700 mm · y(-1) and are consistent with modern precipitation data for eastern Africa. We conclude that freshwater availability exerted a substantial influence on eastern African ecosystems and, by extension, was central to early human proliferation during periods of rapid climate change.
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