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News Article | May 8, 2017
Site: www.eurekalert.org

New research suggests that advances in the production of Early Stone Age tools had less to do with the evolution of language and more to do with the brain networks involved in modern piano playing. Around 1.75 million years ago there was a revolutionary innovation in stone tool technology, when early humans moved from making simple Oldowan flake and pebble tools to producing two-sided, shaped tools, such as Acheulian hand axes and cleavers. This advance is thought to reflect an evolutionary change in intelligence and language abilities. Understanding the link between brain evolution and cognition is a challenge, however, because it is impossible to observe the brain activity of extinct humans. An innovative approach to this challenge is to bring together modern neuroscience methods and material artefacts from the archaeological record. To understand the brain changes that might have co-evolved with the advance in tool use, researchers in the field of neuroarcheology - from the University of East Anglia's (UEA) School of Psychology, The Stone Age Institute at Indiana University, and the Department of Anthropology at the University of Iowa - have been examining the brain activity of modern humans as they learn to make Oldowan and Acheulian stone tools. To test whether learning with language impacts which brain networks are involved in stone toolmaking, 15 of the 31 participants learned to knap stone via verbal instruction by watching videos of a skilled knapper's hands during individual training sessions. The other 16 participants learned via nonverbal instruction using the same videos, but with the sound turned off. The researchers found that the co-ordination of visual attention and motor control networks were sufficient to remove simple flakes for Oldowan tools. But the production of Acheulian tools required the integration of visual working memory, auditory and sensorimotor information, and complex action-planning - the same brain areas that are activated in modern piano playing. These findings, published in the journal Nature Human Behaviour, are a major step forward in understanding the evolution of human intelligence. Lead author Dr Shelby Putt, from the Stone Age Institute, said: "This work offers novel insights into prehistoric cognition using a cutting-edge neuroimaging technique that allows people to engage in complex actions while we are measuring localized brain activity. "The study reveals key brain networks that might underlie the shift towards more human-like intelligence around 1.75 million years ago. We think this marked a turning point in the evolution of the human brain, leading to the evolution of a new species of human." The researchers also reported that brain networks specialised for language in modern humans were only activated during Acheulian tool production when participants learned to make tools in the verbal instruction condition. Since language was likely not available 1.75 million years ago, this suggests that Acheulian tool production did not rely heavily on the evolution of language centres in the brain. Co-author Prof John Spencer from UEA said: "Our findings do not neatly overlap with prior claims that language and stone tool production co-evolved. There is more support for the idea that working memory and auditory-visual integration networks laid the foundation for advances in stone tool-making. "It is fascinating that these same brain networks today allow modern humans to perform such behaviours as skilfully playing a musical instrument." Previous studies have attempted to simulate early tool making, for example, by showing participants images of tool production and then looking at brain activity. Conducted at the University of Iowa, this is the first neuroimaging study to use a cutting-edge technique - functional near-infrared spectroscopy (fNIRS) - to enable researchers to track real time changes in brain activity as participants made these two types of stone tools. Summing up the study, co-author Prof Robert Franciscus from the University of Iowa said: "When and how humans became the exceptionally intelligent and language-using species that we are today is still a great mystery. We discovered that the appearance of a type of more complexly shaped stone tool kit in the archaeological record marked an important cognitive shift when our ancestors started to think and act more like humans rather than apes. "The insights provided by this study into some of the biggest questions in human evolution - cognitive evolution and its relationship to the emergence of language - would have been difficult, if not impossible to achieve without the kind of interdisciplinary approach to research that this project was grounded on." 'The Functional Brain Networks that Underlie Early Stone Age Tool Manufacture', Shelby S Putt, Sobanawartiny Wijeakumar, Robert G Franciscus, John P Spencer, is published in Nature Human Behaviour.


News Article | May 8, 2017
Site: phys.org

Around 1.75 million years ago there was a revolutionary innovation in stone tool technology, when early humans moved from making simple Oldowan flake and pebble tools to producing two-sided, shaped tools, such as Acheulian hand axes and cleavers. This advance is thought to reflect an evolutionary change in intelligence and language abilities. Understanding the link between brain evolution and cognition is a challenge, however, because it is impossible to observe the brain activity of extinct humans. An innovative approach to this challenge is to bring together modern neuroscience methods and material artefacts from the archaeological record. To understand the brain changes that might have co-evolved with the advance in tool use, researchers in the field of neuroarcheology - from the University of East Anglia's (UEA) School of Psychology, The Stone Age Institute at Indiana University, and the Department of Anthropology at the University of Iowa - have been examining the brain activity of modern humans as they learn to make Oldowan and Acheulian stone tools. To test whether learning with language impacts which brain networks are involved in stone toolmaking, 15 of the 31 participants learned to knap stone via verbal instruction by watching videos of a skilled knapper's hands during individual training sessions. The other 16 participants learned via nonverbal instruction using the same videos, but with the sound turned off. The researchers found that the co-ordination of visual attention and motor control networks were sufficient to remove simple flakes for Oldowan tools. But the production of Acheulian tools required the integration of visual working memory, auditory and sensorimotor information, and complex action-planning - the same brain areas that are activated in modern piano playing. These findings, published in the journal Nature Human Behaviour, are a major step forward in understanding the evolution of human intelligence. Lead author Dr Shelby Putt, from the Stone Age Institute, said: "This work offers novel insights into prehistoric cognition using a cutting-edge neuroimaging technique that allows people to engage in complex actions while we are measuring localized brain activity. "The study reveals key brain networks that might underlie the shift towards more human-like intelligence around 1.75 million years ago. We think this marked a turning point in the evolution of the human brain, leading to the evolution of a new species of human." The researchers also reported that brain networks specialised for language in modern humans were only activated during Acheulian tool production when participants learned to make tools in the verbal instruction condition. Since language was likely not available 1.75 million years ago, this suggests that Acheulian tool production did not rely heavily on the evolution of language centres in the brain. Co-author Prof John Spencer from UEA said: "Our findings do not neatly overlap with prior claims that language and stone tool production co-evolved. There is more support for the idea that working memory and auditory-visual integration networks laid the foundation for advances in stone tool-making. "It is fascinating that these same brain networks today allow modern humans to perform such behaviours as skilfully playing a musical instrument." Previous studies have attempted to simulate early tool making, for example, by showing participants images of tool production and then looking at brain activity. Conducted at the University of Iowa, this is the first neuroimaging study to use a cutting-edge technique - functional near-infrared spectroscopy (fNIRS) - to enable researchers to track real time changes in brain activity as participants made these two types of stone tools. Summing up the study, co-author Prof Robert Franciscus from the University of Iowa said: "When and how humans became the exceptionally intelligent and language-using species that we are today is still a great mystery. We discovered that the appearance of a type of more complexly shaped stone tool kit in the archaeological record marked an important cognitive shift when our ancestors started to think and act more like humans rather than apes. "The insights provided by this study into some of the biggest questions in human evolution - cognitive evolution and its relationship to the emergence of language - would have been difficult, if not impossible to achieve without the kind of interdisciplinary approach to research that this project was grounded on." 'The Functional Brain Networks that Underlie Early Stone Age Tool Manufacture', Shelby S Putt, Sobanawartiny Wijeakumar, Robert G Franciscus, John P Spencer, is published in Nature Human Behaviour. Explore further: Language and tool-making skills evolved at same time, study says More information: Shelby S. Putt et al, The functional brain networks that underlie Early Stone Age tool manufacture, Nature Human Behaviour (2017). DOI: 10.1038/s41562-017-0102


News Article | May 9, 2017
Site: www.futurity.org

By using highly advanced brain-imaging technology to observe modern humans making ancient tools, it is now believed that human-like ways of thinking may have emerged as early as 1.8 million years ago. The findings place the appearance of human-like cognition at the emergence of Homo erectus, an early apelike species of human first found in Africa whose evolution predates Neanderthals by nearly 600,000 years. “This is a significant result because it’s commonly thought our most modern forms of cognition only appeared very recently in terms of human evolutionary history,” says Shelby S. Putt, a postdoctoral researcher with The Stone Age Institute at Indiana University, and first author of the study in the journal Nature Human Behavior. “But these results suggest the transition from apelike to human-like ways of thinking and behaving arose surprisingly early.” The conclusions are based on brain activity in modern individuals who were taught to create two types of ancient tools: simple Oldowan-era “flake tools”—little more than broken rocks with a jagged edge—and more complicated Acheulian-era hand axes, which resemble a large arrowhead. Both are formed by smashing rocks together using a process known as “flintknapping.” Oldowan tools, which first appeared about 2.6 million years ago, are among the earliest used by humanity’s ancestors. Acheulian-era tool use dates from 1.8 million to 100,000 years ago. Neuroarchaeologists need to look to modern humans to understand how pre-human species evolved cognition since the act of thinking—unlike fossilized bones or ancient artifacts—leave no physical trace in the archaeological record. Until recently, the methods used to conduct studies on modern humans crafting ancient tools were limited by brain imaging technology. Previous studies depended on placing people within the confines of a functional magnetic resonance imaging machine to observe their brain activity while watching videos of people crafting tools. The new study used more advanced functional near-infrared spectroscopy—a device that resembles a lightweight cap with numerous wires used to shine highly sensitive lasers onto the scalp—to observe brain activity in people as they learned to craft both types of tools with their hands. In the study, 15 volunteers were taught to craft both types of tools through verbal instruction via videotape. An additional 16 volunteers were shown the same videos without sound to learn toolmaking through nonverbal observation. The experiments took place in the lab of John P. Spencer at the University of Iowa, where Putt earned her PhD. Brain scans showed visual attention and motor control were required to create the simpler Oldowan tools. A much larger portion of the brain was engaged in the creation of the more complex Acheulian tools, including regions of the brain associated with the integration of visual, auditory, and sensorimotor information; the guidance of visual working memory; and higher-order action planning. “The fact that these more advanced forms of cognition were required to create Acheulean hand axes—but not simpler Oldowan tools—means the date for this more humanlike type of cognition can be pushed back to at least 1.8 million years ago, the earliest these tools are found in the archaeological record,” Putt says. “Strikingly, these parts of the brain are the same areas engaged in modern activities like playing the piano.” Coauthors are from the University of East Anglia and the University of Iowa. The Wenner-Gren Foundation; the Leakey Foundation; Sigma Xi, the Scientific Research Society; the American Association of University Women; and the University of Iowa funded the work.


News Article | May 9, 2017
Site: www.biosciencetechnology.com

By using highly advanced brain imaging technology to observe modern humans crafting ancient tools, an Indiana University neuroarchaeologist has found evidence that human-like ways of thinking may have emerged as early as 1.8 million years ago. The results, reported May 8 in the journal Nature Human Behavior, place the appearance of human-like cognition at the emergence of Homo erectus, an early apelike species of human first found in Africa whose evolution predates Neanderthals by nearly 600,000 years. "This is a significant result because it's commonly thought our most modern forms of cognition only appeared very recently in terms of human evolutionary history," said Shelby S. Putt, a postdoctoral researcher with The Stone Age Institute at Indiana University, who is first author on the study. "But these results suggest the transition from apelike to humanlike ways of thinking and behaving arose surprisingly early." The study's conclusions are based upon brain activity in modern individuals taught to create two types of ancient tools: simple Oldowan-era "flake tools" -- little more than broken rocks with a jagged edge -- and more complicated Acheulian-era hand axes, which resemble a large arrowhead. Both are formed by smashing rocks together using a process known as "flintknapping." Oldowan tools, which first appeared about 2.6 million years ago, are among the earliest used by humanity's ancestors. Acheulian-era tool use dates from 1.8 million to 100,000 years ago. Putt said that neuroarchaeologists look to modern humans to understand how pre-human species evolved cognition since the act of thinking -- unlike fossilized bones or ancient artifacts -- leave no physical trace in the archaeological record. The methods used to conduct studies on modern humans crafting ancient tools was limited until recently by brain imaging technology. Previous studies depended on placing people within the confines of a functional magnetic resonance imaging machine -- essentially a narrow mental tube -- to observe their brain activity while watching videos of people crafting tools. Putt's study, by contrast, employed more advanced functional near-infrared spectroscopy -- a device that resembles a lightweight cap with numerous wires used to shine highly sensitive lasers onto the scalp -- to observe brain activity in people as they learned to craft both types of tools with their hands. In the study, 15 volunteers were taught to craft both types of tools through verbal instruction via videotape. An additional 16 volunteers were shown the same videos without sound to learn toolmaking through nonverbal observation. These experiments were conducted in the lab of John P. Spencer at the University of Iowa, where Putt earned her Ph.D. before joining IU. Spencer is now a faculty member at the University of East Anglia. The resulting brain scans revealed that visual attention and motor control were required to create the simpler Oldowan tools. A much larger portion of the brain was engaged in the creation of the more complex Acheulian tools, including regions of the brain associated with the integration of visual, auditory and sensorimotor information; the guidance of visual working memory; and higher-order action planning. "The fact that these more advanced forms of cognition were required to create Acheulean hand axes -- but not simpler Oldowan tools -- means the date for this more humanlike type of cognition can be pushed back to at least 1.8 million years ago, the earliest these tools are found in the archaeological record," Putt said. "Strikingly, these parts of the brain are the same areas engaged in modern activities like playing the piano."


News Article | May 8, 2017
Site: www.eurekalert.org

By using highly advanced brain imaging technology to observe modern humans crafting ancient tools, an Indiana University neuroarchaeologist has found evidence that human-like ways of thinking may have emerged as early as 1.8 million years ago. The results, reported May 8 in the journal Nature Human Behavior, place the appearance of human-like cognition at the emergence of Homo erectus, an early apelike species of human first found in Africa whose evolution predates Neanderthals by nearly 600,000 years. "This is a significant result because it's commonly thought our most modern forms of cognition only appeared very recently in terms of human evolutionary history," said Shelby S. Putt, a postdoctoral researcher with The Stone Age Institute at Indiana University, who is first author on the study. "But these results suggest the transition from apelike to humanlike ways of thinking and behaving arose surprisingly early." The study's conclusions are based upon brain activity in modern individuals taught to create two types of ancient tools: simple Oldowan-era "flake tools" -- little more than broken rocks with a jagged edge -- and more complicated Acheulian-era hand axes, which resemble a large arrowhead. Both are formed by smashing rocks together using a process known as "flintknapping." Oldowan tools, which first appeared about 2.6 million years ago, are among the earliest used by humanity's ancestors. Acheulian-era tool use dates from 1.8 million to 100,000 years ago. Putt said that neuroarchaeologists look to modern humans to understand how pre-human species evolved cognition since the act of thinking -- unlike fossilized bones or ancient artifacts -- leave no physical trace in the archaeological record. The methods used to conduct studies on modern humans crafting ancient tools was limited until recently by brain imaging technology. Previous studies depended on placing people within the confines of a functional magnetic resonance imaging machine -- essentially a narrow mental tube -- to observe their brain activity while watching videos of people crafting tools. Putt's study, by contrast, employed more advanced functional near-infrared spectroscopy -- a device that resembles a lightweight cap with numerous wires used to shine highly sensitive lasers onto the scalp -- to observe brain activity in people as they learned to craft both types of tools with their hands. In the study, 15 volunteers were taught to craft both types of tools through verbal instruction via videotape. An additional 16 volunteers were shown the same videos without sound to learn toolmaking through nonverbal observation. These experiments were conducted in the lab of John P. Spencer at the University of Iowa, where Putt earned her Ph.D. before joining IU. Spencer is now a faculty member at the University of East Anglia. The resulting brain scans revealed that visual attention and motor control were required to create the simpler Oldowan tools. A much larger portion of the brain was engaged in the creation of the more complex Acheulian tools, including regions of the brain associated with the integration of visual, auditory and sensorimotor information; the guidance of visual working memory; and higher-order action planning. "The fact that these more advanced forms of cognition were required to create Acheulean hand axes -- but not simpler Oldowan tools -- means the date for this more humanlike type of cognition can be pushed back to at least 1.8 million years ago, the earliest these tools are found in the archaeological record," Putt said. "Strikingly, these parts of the brain are the same areas engaged in modern activities like playing the piano." In addition to Spencer, other authors on the study were Sobanawartiny Wijeakumar of the University of East Anglia and Robert Franciscus of the University of Iowa. The research was supported in part by the Wenner-Gren Foundation; the Leakey Foundation; Sigma Xi, the Scientific Research Society; the American Association of University Women; and the University of Iowa. Putt also said the study was inspired in part by a similar experiment previously performed at IU by Nicholas Toth and Kathy Schick, both professors in the IU College of Arts and Sciences' Cognitive Science Program and co-directors of The Stone Age Institute, and Dietrich Stout, a Ph.D. student in their lab who is now a faculty member at Emory University in Georgia. Putt joined IU in part to pursue additional research on human cognition at The Stone Age Institute under support from the institute's $3.2 million grant from the Temple Foundation in 2016.


Stout D.,Emory University | Semaw S.,The Stone Age Institute | Semaw S.,Indiana University Bloomington | Rogers M.J.,Southern Connecticut State University | Cauche D.,French Natural History Museum
Journal of Human Evolution | Year: 2010

Inter-site technological variation in the archaeological record is one of the richest potential sources of information about Plio-Pleistocene hominid behavior and evolution. However, appropriate methods for describing and comparing Oldowan assemblages have yet to be agreed upon, and interpretation of the early record remains highly controversial. Particularly salient is disagreement over whether the Oldowan is a single technological phenomenon or is more accurately divided into multiple regional and/or chronological traditions, perhaps including a less developed Pre-Oldowan phase in the late Pliocene. Some of this disagreement reflects theoretical and methodological differences between research traditions and some is more directly evidential. Here we present a framework for describing and interpreting Oldowan variation and apply it to three Pliocene assemblages (EG-10, EG-12, and OGS-7) from Gona, all dated to c. 2.6 million years (Ma). Results indicate proficient knapping and a full range of Oldowan reduction strategies in these earliest known occurrences, consistent with the idea of an Oldowan " technological stasis" from 2.6-1.6. Ma. Patterns of variation in raw material selection and predominant reduction strategy at each site clearly indicate the importance of cultural transmission in the Oldowan, but confounding ecological and economic variation continue to render interpretation in terms of multiple tool making traditions or species inappropriate. We propose that cultural transmission and ecological adaptation should be recognized as complementary, rather than mutually exclusive, mechanisms in future attempts to explain Oldowan technological variation. © 2010 Elsevier Ltd.


Habermann J.M.,Friedrich - Alexander - University, Erlangen - Nuremberg | Stanistreet I.G.,University of Liverpool | Stanistreet I.G.,The Stone Age Institute | Stollhofen H.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 6 more authors.
Journal of Human Evolution | Year: 2016

The discovery of fossil rooted tree stumps in lowermost Lower Bed I from the western Olduvai Basin, Tanzania, age-bracketed by the Naabi Ignimbrite (2.038 ± 0.005 Ma) and TuffIA (1.88 ± 0.05 Ma), provides the first direct, in situ, and to date oldest evidence of living trees at Olduvai Gorge. The tree relicts occur in an interval dominated by low-viscosity mass flow and braided fluvial sediments, deposited at the toe of a largely Ngorongoro Volcano-sourced volcaniclastic fan apron that comprised a widely spaced network of ephemeral braided streams draining northward into the Olduvai Basin. Preservation of the trees occurred through their engulfment by mass flows, post-mortem mold formation resulting from differential decay of woody tissues, and subsequent fluvially-related sediment infill, calcite precipitation, and cast formation. Rhizolith preservation was triggered by the interaction of root-induced organic and inorganic processes to form rhizocretionary calcareous root casts. Phytolith analyses were carried out to complete the paleoenvironmental reconstruction. They imply a pronounced seasonality and indicate a wooded landscape with grasses, shrubs, and sedges growing nearby, comparable to the low, open riverine woodland (unit 4c) along the Garusi River and tributaries in the Laetoli area. Among the tree stump cluster were found outsized lithic clasts and those consisting of quartzite were identified as Oldowan stone tool artifacts. In the context of hominin activity, the identification of wooded grassland in association with nearby freshwater drainages and Oldowan artifacts significantly extends our paleoenvironmental purview on the basal parts of Lower Bed I, and highlights the hitherto underrated role of the yet poorly explored western Olduvai Gorge area as a potential ecologically attractive setting and habitat for early hominins. © 2015 Elsevier Ltd.


Blumenschine R.J.,Rutgers University | Stanistreet I.G.,University of Liverpool | Njau J.K.,Indiana University | Njau J.K.,The Stone Age Institute | And 10 more authors.
Journal of Human Evolution | Year: 2012

We establish through 13 excavations the landscape context and nature of hominin activities across the Zinjanthropus land surface from which the Leakeys recovered the FLK 22 and FLK NN 1 paleoanthropological assemblages. The land surface was created by fluvial incision of the eastern margin of paleo-Lake Olduvai following a major lake withdrawal. Erosion was uneven, leaving a peninsula bounded by a river channel, the FLK Fault, and a freshwater wetland. This FLK Peninsula supported groves of trees that attracted hominins and carnivores, and that preserved the dense concentrations of carcass remains and stone tools they left behind, including those at FLK 22. Some carcasses appear to have been acquired at the ecotone of the Peninsula and Wetland, where another dense artifact and bone assemblage accumulated. A lesser topographic high at the edge of a Typha marsh in the Wetland was the site of FLK NN 1 and a scatter of large stone tools used possibly for rootstock processing. Our landscape reconstruction delimits the vegetation mosaic indicated by previous work and provides a topographical explanation for the existence of FLK 22 and FLK NN 1. Both are unexpected if the FLK area was the flat, featureless lake margin terrain typical of lake basins similar to paleo-Olduvai. The results show that the Leakeys' sites were not isolated occupation floors but rather parts of a land surface utilized intensively by hominins. Although commonly considered to have been home bases, their likely high predation risk, evidenced by large carnivore feeding traces and the remains of four hominin individuals, suggests visits to them were brief and limited to feeding. Finally, stratigraphic observations confirm that FLK NN 3 accumulated on an older land surface, refuting the hypothesis that the OH 8 foot found there is the same individual as the OH 35 leg from FLK 22. © 2011 Elsevier Ltd.


McHenry L.J.,University of Wisconsin - Milwaukee | Njau J.K.,Indiana University | Njau J.K.,The Stone Age Institute | de la Torre I.,University College London | Pante M.C.,Colorado State University
Quaternary Research (United States) | Year: 2016

Bed II is a critical part of early Pleistocene Olduvai Gorge, Tanzania. Its deposits include transitions from humid to more arid conditions (with associated faunal changes), from Homo habilis to erectus, and from Oldowan to Acheulean technology. Bed II (~. 1.8-1.2 Ma) is stratigraphically and environmentally complex, with facies changes, faulting, and unconformities, making site-to-site correlation over the ~. 20 km of exposure difficult. Bed II tuffs are thinner, less evenly preserved, and more reworked than those of Bed I. Five marker tuffs (Tuffs IIA-IID, Bird Print Tuff (BPT)), plus local tephra, were collected from multiple sites and characterized using stratigraphic position, mineral assemblage, and electron probe microanalysis of phenocryst (feldspar, hornblende, augite, titanomagnetite) and glass (where available) composition. Lowermost Bed II tuffs are dominantly nephelinitic, Middle Bed II tuffs (BPT, Tuff IIC) have basaltic components, and upper Bed II Tuff IID is trachytic. The BPT and Tuff IID are identified widely using phenocryst compositions (high-Ca plagioclase and high-Ti hornblende, respectively), though IID was originally (Hay, 1976) misidentified as Tuff IIC at Loc 91 (SHK Annexe) in the Side Gorge. This work helps establish a high-resolution basin-wide paleolandscape context for the Oldowan-Acheulean transition and helps link hominin, faunal and archaeological records. © 2015 University of Washington.


Habermann J.M.,Friedrich - Alexander - University, Erlangen - Nuremberg | McHenry L.J.,University of Wisconsin - Milwaukee | Stollhofen H.,Friedrich - Alexander - University, Erlangen - Nuremberg | Tolosana-Delgado R.,Helmholtz Institute Freiberg for Resource Technology | And 3 more authors.
Sedimentary Geology | Year: 2016

The chronology of Pleistocene flora and fauna, including hominin remains and associated Oldowan industries in Bed I, Olduvai Gorge, Tanzania, is primarily based on 40Ar/39Ar dating of intercalated tuffs and lavas, combined with detailed tephrostratigraphic correlations within the basin. Although a high-resolution chronostratigraphic framework has been established for the eastern part of the Olduvai Basin, the western subbasin is less well known due in part to major lateral facies changes within Bed I combined with discontinuous exposure. We address these correlation difficulties using the discriminative power of the chemical composition of the major juvenile mineral phases (augite, anorthoclase, plagioclase) from tuffs, volcaniclastic sandstones, siliciclastic units, and lavas. We statistically evaluate these compositions, obtained from electron probe micro-analysis, applying principal component analysis and discriminant analysis to develop discriminant models that successfully classify most Bed I volcanic units. The correlations, resulting from integrated analyses of all target minerals, provide a basin-wide Bed I chemostratigraphic framework at high lateral and vertical resolution, consistent with the known geological context, that expands and refines the geochemical databases currently available. Correlation of proximal ignimbrites at the First Fault with medial and distal Lower Bed I successions of the western basin enables assessment of lateral facies and thickness trends that confirm Ngorongoro Volcano as the primary source for Lower Bed I, whereas Upper Bed I sediment supply is mainly from Olmoti Volcano. Compositional similarity between Tuff IA, Bed I lava, and Mafic Tuffs II and III single-grain fingerprints, together with north- and northwestward thinning of Bed I lava, suggests a common Ngorongoro source for these units. The techniques applied herein improve upon previous work by evaluating compositional affinities with statistical rigor rather than primarily relying on visual comparison of bivariate plots. © 2016 Elsevier B.V.

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