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International audience; Goda Buticha (“Cave of Ghosts” in the local Afaan Oromoo language), located near Dire Dawa in Eastern Ethiopia is one of the few sites documenting Late Pleistocene and Holocene human occupation in the Horn of Africa. Its preserved long stratigraphical sequence (more than 2 meters deep) records human presence from ~63 ka, and highlights a major chronological gap from ~23 ka to 8 ka, which prevents (as it is the case for other sites in the region) a direct documentation of the transition from the Middle to the Later Stone Age. However, it raises important issues in terms ofcultural (dis)continuity between the late Pleistocene and Mid-Holocene in the Horn. Beyond the technical features described at the site, the results from the comparative analysis are integrated with the chronological, sedimentological and palaeoenvironmental studies, and discussed at the regional scale. The lithic assemblage from the lower units of Goda Buticha (~63-23 ka) are characterised by typical MSA features, such as the use of Levallois flaking system and retouched points. High frequencies of elongated blanks may recall the MSA assemblage of Porc-Epic but the assemblage at Goda Buticha differs from the one of Porc-Epic by a more frequent use of obsidian and a trend towards the production of smaller blanks. These results highlight the variability within the Late Pleistocene MSA in the Horn of Africa.The assemblages from the upper layers (mid-Holocene) at Goda Buticha offer a complex picture, with the occurrence of both MSA and LSA features. They may represent very local adaptations, reintroduction of MSA characteristics within an LSA context or continuity into recent periods. It is interesting to note that the nearby terminal Pleistocene levels of Laas Geel shelter 7 are also characterised by such a combination of MSA and LSA features. The results add to the evidence for great variability of lithic technologies across Africa at the end of the Pleistocene and Holocene and may have implications for major questions, central to the understanding of this period: adaptation to climatic instability (the “Big Dry”) and population movements allowing us to highlight great cultural diversity whether linked with spatial ("regional identity"), or temporal (Early vs Late MSA) variability. Therefore, the LMSA of the Horn appears not to be a monolithic entity, and, in its variability as wellas in its features represents a behavioural patchwork, which makes its integration into the general models of the H. s. dispersals during the Late Pleistocene difficult. It also and mostly highlights the need to continue first working in smaller scale units, and questions the MIS 3 & 2 human occupations at a local scale.; éthiopien, est l’un des rares sites documentant l’occupation humaine de la fin Pléistocène et de l’Holocène dans la Corne de l’Afrique. Sa longue séquence stratigraphique (>2 mètres) enregistre des séries d’occupations depuis ~60 ka et met en évidence un hiatus chronologique et sédimentaire majeur de plus de 15 000 ans (~23-7 ka BP). Sans permettre d’appréhender directement, à l’instar des principaux sites de la région, la transition Middle/Later Stone Age (MSA/LSA), elle est un témoin privilégié pour discuter des (dis)continuités techno-culturelles à la fin du Pléistocène supérieur et à l’Holocène dans la Corne. La rareté des sites présentant de longues séquences dans cette région empêche également une compréhension à grande échelle de la dispersion des groupes humains ou de la diffusion comportementale.Au-delà des caractéristiques techniques, les résultats de l’analyse comparative du site sont intégrés aux études chronologiques, sédimentologiques et paléoenvironnementales, puis examinés à l’échelle régionale. L’étude du mobilier archéologique des couches inférieures de la séquence (~63-23 ka) met en évidence des caractéristiques MSA typiques telles que l’utilisation de modalités Levallois du débitage ou la confection de pointes unies ou bifaciales. La production de supports allongés peut en particulier faire écho au faciès MSA du site voisin de Porc-Epic, où l’usage plus généralisé de l’obsidienne ainsi qu’une composante lamellaire plus importante distinguent néanmoins fortement les deux assemblages l’un de l’autre.Les assemblages des couches supérieures (Holocène moyen) offrent une image « plus complexe », dans la mesure où des caractéristiques mixtes MSA et LSA sont apparentes, interrogeant directement sur une adaptation très locale des populations, la réintroduction de composantes MSA dans un contexte LSA ou une continuité technique jusqu’à des périodes récentes. Il est intéressant de noter en particulier que les niveaux du Pléistocène final de Laas Geel 7 (Somaliland) sont égalementcaractérisés par une telle mixité technique MSA/LSA. Au final, Goda Buticha est donc un exemple de la grande variabilité comportementale dans la Corne de l’Afrique à la fin du Pléistocène et à l’Holocène, avec des implications pour comprendre l’adaptation des populations à l’instabilité climatique du « Big Dry ».La transition MSA/LSA de la Corne, difficile à appréhender, ne semble pas être liée à deschangements monolithiques, mais plutôt relever d’un glissement comportemental multifacette quirend difficile son insertion dans les modèles généraux de la dispersion des Homo sapiens. Celasouligne également la nécessité de poursuivre l’investigation sur les occupations humaines de cettepériode dans leur cadre climatique et environnementale à une échelle avant tout locale.

The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012-2014 HSPDP coring campaign.

The Chew Bahir Drilling Project (CBDP) aims to test possible linkages between climate and evolution in Africa through the analysis of sediment cores that have recorded environmental changes in the Chew Bahir basin. In this statistical project we consider the Chew Bahir palaeolake to be a dynamical system consisting of interactions between its different components, such as the waterbody, the sediment beneath lake, and the organisms living within and around the lake. Recurrence is a common feature of such dynamical systems, with recurring patterns in the state of the system reflecting typical influences. Identifying and defining these influences contributes significantly to our understanding of the dynamics of the system. Different recurring changes in precipitation, evaporation, and wind speed in the Chew Bahir basin could result in similar (but not identical) conditions in the lake (e.g., depth and area of the lake, alkalinity and salinity of the lake water, species assemblages in the water body, and diagenesis in the sediments). Recurrence plots (RPs) are graphic displays of such recurring states within a system. Measures of complexity were subsequently introduced to complement the visual inspection of recurrence plots, and provide quantitative descriptions for use in recurrence quantification analysis (RQA). We present and discuss herein results from an RQA on the environmental record from six short (< 17 m) sediment cores collected during the CBDP, spanning the last 45 kyrs. The different types of variability and transitions in these records were classified to improve our understanding of the response of the biosphere to climate change, and especially the response of humans in the area.

We used a change point analysis on a late Pleistocene-Holocene lake-sediment record from the Chew Bahir basin in the southern Ethiopian Rift to determine the amplitude and duration of past climate transitions. The most dramatic changes occurred over 240 yr (from similar to 15,700 to 15,460 yr) during the onset of the African Humid Period (AHP), and over 990 yr (from similar to 4875 to 3885 yr) during its protracted termination. The AHP was interrupted by a distinct dry period coinciding with the high-latitude Younger Dryas stadial, which had an abrupt onset (less than similar to 100 yr) at similar to 13,260 yr and lasted until similar to 11,730 yr. Wet-dry-wet transitions prior to the AHP may reflect the high-latitude Dansgaard-Oeschger cycles, as indicated by cross-correlation of the potassium record with the NorthGRIP ice core record between similar to 45-20 ka. These findings may contribute to the debates regarding the amplitude, and duration and mechanisms of past climate transitions, and their possible influence on the development of early modern human cultures.

International audience

The content of this volume originates in the organization of a special panel for the 18th International Conference of Ethiopian Studies (ICES) held in Dire Dawa, Ethiopia, in OctobereNovember 2012. This conference addressed the issue of “movements” in its broadest sense: studies on social, religious, political, and cultural movements but also on circulation of words, ideas and peoples; the dynamics of contacts and exchanges; the effect of intellectual or economic change on societies; as well as “movement ” in its concrete physical and spatial meaning at different time and geographical scales. Our contribution to this conference meant to address different levels of understanding of the concept of “movement” in prehistoric archaeology and human evolution, especially in Ethiopia that is alternately considered to be a cradle, point of origin for dispersal, or a refugium zone, of human populations. The concept of “movement” was tackled through multidisciplinary studies, using empirical data from researched sites, and focuses on the paleoenvironmental-palaeoclimatic background to Middle and Upper Pleistocene paleoanthropological record and on the archaeological expressions of the behavioral, chronological and territorial changes, their significance and implications within Ethiopia and the Horn of Africa.

International audience; A growing number of proxy, historical and instrumental data sets are now available from continental Africa through which past variations in temperaturecan be assessed. This paper, co-authored by members of the PAGES Africa2k Working Group, synthesises published material to produce a record oftemperature variability for Africa as a whole spanning the last 2000 years. The paper focuses on temperature variability during the ‘Medieval ClimateAnomaly’ (MCA), ‘Little Ice Age’ (LIA) and late 19th–early 21st centuries. Warmer conditions during the MCA are evident in records from LakeTanganyika in central Africa, the Ethiopian Highlands in northeastern Africa, and Cango Cave, the Kuiseb River and Wonderkrater in southern Africa.Other records covering the MCA give ambiguous signals. Warming appears to have been greater during the early MCA (c. ad 1000) in parts of southernAfrica and during the later MCA (from ad 1100) in Namibia, Ethiopia and at Lake Tanganyika. LIA cooling is evident in Ethiopian and southern Africanpollen records and in organic biomarker data from Lake Malawi in southeastern tropical Africa, while at Lake Tanganyika the temperature depressionappears to have been less consistent. A warming trend in mean annual temperatures is clearly evident from historical and instrumental data coveringthe late 19th to early 21st centuries. General warming has occurred over Africa since the 1880s punctuated only by a period of cooling in the mid 20thcentury. The rate of temperature increase appears to have accelerated towards the end of the 20th century. The few long high-resolution proxy recordsthat extend into the late 20th century indicate that average annual temperatures were 1–2°C higher in the last few decades than during the MCA.

Geoheritage: from geoarchaeology to geotourism. Editorial.

This multidisciplinary work has two major objectives: (i) understanding the structures and textures related to solidification of mafic-felsic magma interactions (mixing and mingling) and their implications ta mechanisms of magma emplacement and pluton construction and (ii) understanding the geodynamic and temporal relationships between two major structures of the Pan-African orogeny in Northeast Africa which met in Ethiopia : the ArabianNubian Shleld (ANS) and the Mozambique Belt (MB). based on a comparative study of Negash (ANS) and Konso plutons (MB). Malic-felsic interactions. Two major types of mafic-feisic magma interactions characterize the Negash pluton: (i)mingling and mixing at the lower mafic-felsic interfaces and (il) strongly mixed and mingled monzodiorites. Structural,mineralogical and chemical data suggest that the pluton was construcled by a successive assemblage of four differentiated magma batches (at intermediate chambers), which were forcefully injectedinto pre-existing foliatedcountry rocks and that the different types of hybridisation are not random but are related ta the dynamics and mechanismof pluton emplacement: (i) monzogranitic followed by granodioritic magmas; (ii) injection of a malt-richmonzodioritic/monzogabbroic tangue into the partially crystaliized felsic magmas resulting in inverted density gradient which in tum led to interactions at the lower interfaces; and (iii) simultaneous rising of granodioritic and monzodioriticmagmas along the same conduit resulting in the strongly hybridised magma which represents the last intrusion. The hybrid rocks are not results of simple binary mixing but involve atleast three end-members (monzoqabbres,monzodiorites and monzogranites/granodiorites). All these data suggest emplacement of differentiated, low viscosity magma batches and that the pluton was constructed by an assembly of successive melt-rich catches (dyking)ANS and MS. The ANS, which is composed of calc-alkaline and juvenile magmatic rocks without any significant pre-Pan-African continental crust, is essentially a zone of accretion. The MB, consisting of juvenile magmatic rocks gneissic-granulitic assemblages, is not only a zone of accretion but also a zone of recycling of older crustal material. Both terrains display similar succession of contemporaneous events and both are zones of accretion, but correspond to distinct geodynamic environments. The Negash and Konso plutons represent late stages of the geodynamic evolution of the Pan-African orogeny in Ethiopia, representing different stages of the Wilson cycle where the Negash pluton is related ta late-tectonic magmatism during the closing stages of arc-arc accretion in the ANS, while the emplacement of the Konso pluton marked a transition from a post-collisional ta anorogenic intra-plate magmatism in the MB. The ANS and the MB in Ethiopia cduld be considered as contemporaneous and representing the same Wilson cycle but they reilect distinct geodynamic contexts and different levels of erosion., Cette étude pluridisciplinaire a deux objectifs principaux: (i) la compréhension des structures et des textures liées aux mélanges magmatiques en relation avec les mécanismes de mise en place des magmas et la construction des plutons granitiques et (ii) la compréhension des relations entre deux domaines géodynamiques de l'orogenèse panafricaine de l'Afrique de NE qui se rejoignent en Ethiopie : le bouclier Arabo-Nubien (ANS) et la chaîne Mozambique (MB), sur une étude comparative de plutons de Negash (dans l'ANS) et de Konso (dans le MB). Mélanges magmatiques. Deux types d'interactions magmatiques acides-basiques caractérisent le pluton de Negash : (i) des mélanges et hybridations à l'interface acide-basique inférieure et (ii) des monzodiorites fortement mélangées et hybridées. Les données structurales, minéralogiques et chimiques suggèrent que le pluton est construit par l'assemblage successif de quatre pulses magmatiques différenciées dans des chambres magmatiques intermédiaires, qui ont été injectées dans un encaissant schistosé, et que les différents types de mélanges ne sont pas aléatoires mais sont liés à la dynamique de mise en place du pluton : (i) injection de magmas monzogranitiques puis granodioritiques ; (ii) injection d'une langue de monzodiorites/monzogabbros dans les faciès précédents créant une instabilité dynamique ; les mélanges à l'interface se sont produits en réponse à l'injection de ce magma basique dans le magma acide partiellement cristallisé ; et (iii) montée simultanée de magmas granodioritiques et monzodioritiques le long d'un même conduit conduisant à des roches fortement hybridées constituant la dernière venue magmatique. Les roches hybrides ne sont pas le résultat d'un mélange binaire simple mais impliquent au moins trois pôles magmatiques (monzogabbros, monzodiorites et monzogranites/granodiorite). Ces interactions magmatiques impliquent de magma de faible viscosité et suggèrent que le pluton s'est formé par agrégations de venues magmatiques riches en liquide. L'ANS et le MB. L'ANS, constitué de roches magmatiques calco-alcalines et juvéniles, sans aucune croûte continentale anté-panafricaine, est essentiellement une zone d'accrétion. Le MB, constitué de roches magmatiques juvéniles et des assemblages gneissiques-granulitiques, est non seulement une zone d'accrétion mais aussi une zone de recyclage de matériaux plus ancien. Les deux domaines montrent une succession des événements similaires de même âges mais représentent deux contextes géodynamiques distincts. Les plutons de Negash et de Konso sont des plutons tardifs dans l'évolution géodynamique du Panafricain, associés à des stades différents du cycle de Wilson, où le pluton de Negash représenterait un magmatisme tardi-tectonique en fin d'accrétion arc-arc dans l'ANS, alors que la mise en place du pluton de Konso marquerait la transition d'un magmatisme post-collision à un magmatisme d'intra-plaque dans le MB. L'ANS et le MB peuvent être considérés comme contemporains et représentent un même cycle de Wilson mais ils reflètent des contextes géodynamiques et des nivaux d'érosion distincts.

This multidisciplinary work has two major objectives: (i) understanding the structures and textures related to solidification of mafic-felsic magma interactions (mixing and mingling) and their implications ta mechanisms of magma emplacement and pluton construction and (ii) understanding the geodynamic and temporal relationships between two major structures of the Pan-African orogeny in Northeast Africa which met in Ethiopia : the ArabianNubian Shleld (ANS) and the Mozambique Belt (MB). based on a comparative study of Negash (ANS) and Konso plutons (MB). Malic-felsic interactions. Two major types of mafic-feisic magma interactions characterize the Negash pluton: (i)mingling and mixing at the lower mafic-felsic interfaces and (il) strongly mixed and mingled monzodiorites. Structural,mineralogical and chemical data suggest that the pluton was construcled by a successive assemblage of four differentiated magma batches (at intermediate chambers), which were forcefully injectedinto pre-existing foliatedcountry rocks and that the different types of hybridisation are not random but are related ta the dynamics and mechanismof pluton emplacement: (i) monzogranitic followed by granodioritic magmas; (ii) injection of a malt-richmonzodioritic/monzogabbroic tangue into the partially crystaliized felsic magmas resulting in inverted density gradient which in tum led to interactions at the lower interfaces; and (iii) simultaneous rising of granodioritic and monzodioriticmagmas along the same conduit resulting in the strongly hybridised magma which represents the last intrusion. The hybrid rocks are not results of simple binary mixing but involve atleast three end-members (monzoqabbres,monzodiorites and monzogranites/granodiorites). All these data suggest emplacement of differentiated, low viscosity magma batches and that the pluton was constructed by an assembly of successive melt-rich catches (dyking)ANS and MS. The ANS, which is composed of calc-alkaline and juvenile magmatic rocks without any significant pre-Pan-African continental crust, is essentially a zone of accretion. The MB, consisting of juvenile magmatic rocks gneissic-granulitic assemblages, is not only a zone of accretion but also a zone of recycling of older crustal material. Both terrains display similar succession of contemporaneous events and both are zones of accretion, but correspond to distinct geodynamic environments. The Negash and Konso plutons represent late stages of the geodynamic evolution of the Pan-African orogeny in Ethiopia, representing different stages of the Wilson cycle where the Negash pluton is related ta late-tectonic magmatism during the closing stages of arc-arc accretion in the ANS, while the emplacement of the Konso pluton marked a transition from a post-collisional ta anorogenic intra-plate magmatism in the MB. The ANS and the MB in Ethiopia cduld be considered as contemporaneous and representing the same Wilson cycle but they reilect distinct geodynamic contexts and different levels of erosion., Cette étude pluridisciplinaire a deux objectifs principaux: (i) la compréhension des structures et des textures liées aux mélanges magmatiques en relation avec les mécanismes de mise en place des magmas et la construction des plutons granitiques et (ii) la compréhension des relations entre deux domaines géodynamiques de l'orogenèse panafricaine de l'Afrique de NE qui se rejoignent en Ethiopie : le bouclier Arabo-Nubien (ANS) et la chaîne Mozambique (MB), sur une étude comparative de plutons de Negash (dans l'ANS) et de Konso (dans le MB). Mélanges magmatiques. Deux types d'interactions magmatiques acides-basiques caractérisent le pluton de Negash : (i) des mélanges et hybridations à l'interface acide-basique inférieure et (ii) des monzodiorites fortement mélangées et hybridées. Les données structurales, minéralogiques et chimiques suggèrent que le pluton est construit par l'assemblage successif de quatre pulses magmatiques différenciées dans des chambres magmatiques intermédiaires, qui ont été injectées dans un encaissant schistosé, et que les différents types de mélanges ne sont pas aléatoires mais sont liés à la dynamique de mise en place du pluton : (i) injection de magmas monzogranitiques puis granodioritiques ; (ii) injection d'une langue de monzodiorites/monzogabbros dans les faciès précédents créant une instabilité dynamique ; les mélanges à l'interface se sont produits en réponse à l'injection de ce magma basique dans le magma acide partiellement cristallisé ; et (iii) montée simultanée de magmas granodioritiques et monzodioritiques le long d'un même conduit conduisant à des roches fortement hybridées constituant la dernière venue magmatique. Les roches hybrides ne sont pas le résultat d'un mélange binaire simple mais impliquent au moins trois pôles magmatiques (monzogabbros, monzodiorites et monzogranites/granodiorite). Ces interactions magmatiques impliquent de magma de faible viscosité et suggèrent que le pluton s'est formé par agrégations de venues magmatiques riches en liquide. L'ANS et le MB. L'ANS, constitué de roches magmatiques calco-alcalines et juvéniles, sans aucune croûte continentale anté-panafricaine, est essentiellement une zone d'accrétion. Le MB, constitué de roches magmatiques juvéniles et des assemblages gneissiques-granulitiques, est non seulement une zone d'accrétion mais aussi une zone de recyclage de matériaux plus ancien. Les deux domaines montrent une succession des événements similaires de même âges mais représentent deux contextes géodynamiques distincts. Les plutons de Negash et de Konso sont des plutons tardifs dans l'évolution géodynamique du Panafricain, associés à des stades différents du cycle de Wilson, où le pluton de Negash représenterait un magmatisme tardi-tectonique en fin d'accrétion arc-arc dans l'ANS, alors que la mise en place du pluton de Konso marquerait la transition d'un magmatisme post-collision à un magmatisme d'intra-plaque dans le MB. L'ANS et le MB peuvent être considérés comme contemporains et représentent un même cycle de Wilson mais ils reflètent des contextes géodynamiques et des nivaux d'érosion distincts.

Efforts to date the oldest modern human fossils in eastern Africa, from Omo-Kibish1-3 and Herto4,5 in Ethiopia, have drawn on a variety of chronometric evidence, including 40Ar/39Ar ages of stratigraphically associated tuffs. The ages that are generally reported for these fossils are around 197 thousand years (kyr) for the Kibish Omo I3,6,7, and around 160-155 kyr for the Herto hominins5,8. However, the stratigraphic relationships and tephra correlations that underpin these estimates have been challenged6,8. Here we report geochemical analyses that link the Kamoya's Hominid Site (KHS) Tuff9, which conclusively overlies the member of the Omo-Kibish Formation that contains Omo I, with a major explosive eruption of Shala volcano in the Main Ethiopian Rift. By dating the proximal deposits of this eruption, we obtain a new minimum age for the Omo fossils of 233 �� 22 kyr. Contrary to previous arguments6,8, we also show that the KHS Tuff does not correlate with another widespread tephra layer, the Waidedo Vitric Tuff, and therefore cannot anchor a minimum age for the Herto fossils. Shifting the age of the oldest known Homo sapiens fossils in eastern Africa to before around 200 thousand years ago is consistent with independent evidence for greater antiquity of the modern human lineage10., Leverhulme Trust Cambridge-Africa ALBORADA Research Fund SFI award 13/RC/2092

Reconstructions of climatic and environmental conditions can contribute to current debates about the factors that influenced early human dispersal within and beyond Africa. Here we analyse a 200,000-year multi-proxy paleoclimate record from Chew Bahir, a tectonic lake basin in the southern Ethiopian rift. Our record reveals two modes of climate change, both associated temporally and regionally with a specific type of human behavior. The first is a long-term trend towards greater aridity between 200,000 and 60,000 years ago, modulated by precession-driven wet-dry cycles. Here, more favorable wetter environmental conditions may have facilitated long-range human expansion into new territory, while less favorable dry periods may have led to spatial constriction and isolation of local human populations. The second mode of climate change observed since 60,000 years ago mimics millennial to centennial-scale Dansgaard-Oeschger cycles and Heinrich events. We hypothesize that human populations may have responded to these shorter climate fluctuations with local dispersal between montane and lowland habitats.