Project Database

Abstract:

Studies of early human settlement in alpine environments provide insights into human physiological, genetic, and cultural adaptation potentials. Although Late and even Middle Pleistocene human presence has been recently documented on the Tibetan Plateau, little is known regarding the nature and context of early persistent human settlement in high elevations. Here, we report the earliest evidence of a prehistoric high-altitude residential site. Located in Africa’s largest alpine ecosystem, the repeated occupation of Fincha Habera rock shelter is dated to 47 to 31 thousand years ago.The available resources in cold and glaciated environments included the exploitation of an endemic rodent as a key food source, and this played a pivotal role in facilitating the occupation of this site by Late Pleistocene hunter-gatherers.

Abstract:

Ethiopia is rich in obsidian and prehistoric peoples were utilizing it to make artifacts since at least the Early Stone Age. The unique chemical compositions of obsidian are of considerable interest to archaeologists when obsidian artifacts are recovered at prehistoric sites, both in terms of determining provenance and cultural exchange. Here we present electron microprobe analyses to characterize the major and minor element compositions of a suite of obsidian samples from 45 volcanic source locations along a 700 km extent of the Main Ethiopian Rift and the Afar Triangle. Of the 62 analyzed obsidian, 50 are classified as rhyolite, with subordinate numbers of trachyte and dacite. The Main Ethiopian Rift and its extension into the Afar region to the north have produced obsidian with different chemical affinities which may prove useful in narrowing down possible source regions for artifacts for which sources have not yet been discovered and/or analyzed.

Abstract:

Climatic change is widely acknowledged to have played a role in the dispersal of modern humans out of Africa, but the timing is contentious. Genetic evidence links dispersal to climatic change ~60,000 years ago, despite increasing evidence for earlier modern human presence in Asia. We report a deep seismic and near-continuous core record of the last 150,000 years from Lake Tana, Ethiopia, close to early modern human fossil sites and to postulated dispersal routes. The record shows varied climate towards the end of the penultimate glacial, followed by an abrupt change to relatively stable moist climate during the last interglacial. These conditions could have favoured selection for behavioural versatility, population growth and range expansion, supporting models of early, multiple dispersals of modern humans from Africa.

Abstract:

The presentation introduces a new interdisciplinary approach for the reconstruction of Quaternary abiotic, biotic and cultural changes in African model highland environments of southern Ethiopia (Sanetti Plateau, Bale Mountains National Park). High altitude ecosystems are still widely perceived as natural and anthropogenic transformation is generally considered to be concentrated on lower elevations and late. However, recent studies challenge this view and for quaternary environmental science and prehistory, the question where humans retreated to during the driest intervals of the last 20 ka when lowlands may have become uninhabitable is still demanding. Scientific goals of our archaeological project are the reconstruction of the settlement history of the Bale Mountains and the diachronic examination of the interplay between humans and their environment during the late Quaternary landscape evolution. Vertical migration of highly mobile hunter-gatherer groups to montane refugia is suggested as a form of adaptation to abrupt arid events. Human agency, i.e. environment independent decisions could account for non-climate migration patterns.

Abstract:

Long-held views of high-altitudes as natural ecosystems characterized by late anthropogenic transformation processes have recently been challenged by studies carried out on the world’s high plateaus. This is all the more relevant in light of the demanding question where prehistoric populations retreated to, especially during arid intervals, when lowlands may have become uninhabitable. In this presentation we introduce an interdisciplinary approach for the reconstruction of Quaternary abiotic, biotic and cultural changes in African model highland environments of southern Ethiopia. The Bale Mountains represent the largest afro-alpine ecosystem of the continent. They are characterized by a very high biodiversity including a large number of endemic species and they host relevant archives to reconstruct the coupled landscape and human history. First results of a joint Ethio-European research unit (“The Mountain Exile Hypothesis”, funded by the Deutsche Forschungsgemeinschaft) summarized here, comprise archeological, archeozoological, soil biogeochemical and glacial chronological studies and concentrate on the earliest human occupation and persistent use of the available resources. The Bale Mountains feature the oldest evidence for humans in high-altitudes. Late Pleistocene hunter-gatherers must have been very familiar with the then glaciated environment. In immediate vicinity to valley glaciers, high-quality obsidian was regularly and repeatedly extracted from primary outcrops located above 4200 m asl, the highest known occurrences in Ethiopia. Settlement and subsistence activities concentrated on the ice-free areas with access to melt-water. Prehistoric foragers were moreover capable of developing unique subsistence strategies for sustainable and continuous survival and to satisfy the higher caloric demands of living in these altitudes. The associated Middle Stone Age material culture shows the existence of networks to lowlands, but at the same time exhibit the development of distinctive and independent technological traditions.

Abstract:

Archaeological findings, numerical human dispersal models and genome analyses suggest several time windows in the past 200 kyr (thousands of years ago) when anatomically modern humans (AMH) dispersed out of Africa into the Levant and/or Arabia. From close to the key hominin site of Omo-Kibish, we provide near continuous proxy evidence for environmental changes in lake sediment cores from the Chew Bahir basin, south Ethiopia. The data show highly variable hydroclimate conditions from 116 to 66 kyr BP with rapid shifts from very wet to extreme aridity. The wet phases coincide with the timing of the North African Humid Periods during MIS5, as defined by Nile discharge records from the eastern Mediterranean. The subsequent record at Chew Bahir suggests stable regional hydrological setting between 58 and 32 kyr (MIS4 and 3), which facilitated the development of more habitable ecosystems, albeit in generally dry climatic conditions. This shift, from more to less variable hydroclimate, may help account for the timing of later dispersal events of AMH out of Africa.

Abstract:

The high-altitude regions of African tropical environments are among the least studied areas regarding the dispersal and colonization of anatomically modern humans across and out of Africa. Human colonization of high altitude regions is considered a relatively recent process, not least as high-altitude environments are usually perceived as unfavorable for human subsistence and are believed to have functioned as a migration barrier due to their physiological and ecological challenges, including high-altitude hypoxia, cold stress and lack of sufficient resources. Although it is not yet clear when and how human population dispersed into the high-altitude mountains of tropical Africa, our new findings suggest that specialized hunter-gatherer successfully colonized and exploited a wide range of ‘harsh’ landscapes of the Bale Mountains (>3800m asl) in the southeastern Ethiopian Highlands during the Late and Terminal Pleistocene up to Middle and Late Holocene. Moreover, ongoing archaeological research in the northwestern part of the Bale Mountains provides new perspectives on human colonization of high-altitude tropical environments and the relationship between human adaptation and climate changes at least during three separate time periods between 31,000 cal. BP and 4,000 cal BP.

Abstract:

This dissertation presents complex cultural adaptations to the largest Afroalpine ecosystem of the continent: the high-altitude Bale Mountains in the Southeastern Ethiopian Highlands. Human occupation of African tropical highland environments is considered a relatively recent development due to the general perception of high altitude environments as unfavorable for human subsistence. Moreover, these environments are believed to have functioned as a migration barrier in the past, due to their physiological challenges, such as high-altitude hypoxia, higher energy demand, cold stress, or UV radiation. As a consequence, the high-altitude regions remained among the least researched areas in several disciplines. Archaeological research in Ethiopia is still today largely concentrated on the main Rift Valley and on the landscapes and ecosystems of elevations below 2500 m above sea level. Thus, the western part of the Southeastern Ethiopian Highlands, particularly the Arsi-Bale complex landmass, is one of the most neglected regions for the study of Middle and Later Stone Age cultural changes. Only recently, an interdisciplinary research unit (DFG FOR 2358, The Mountain Exile Hypothesis) was established to reconstruct the coupled landscape and human history of the Bale Mountains. In contrast to the general perception, it is hypothesized that especially during arid Quaternary climate phases, the well-watered and stable ecosystems of the Bale Mountains might have even acted as a glacial refuge for plants and animals, but humans as well. As part of the contribution of this research group, the goal of this dissertation is to investigate the evidence of prehistoric hunter-gatherer settlements and cultural responses to high-altitude environments. Archaeological survey and excavations on three selected rock shelters in the upper Web Valley in the northwest of the Bale Mountains provided evidence of prehistoric hunter-gatherer’s occupations dating back to 47 ka cal. BP and continuing until the end of the Holocene around 2 ka cal. BP. At least four major Paleolithic occupational events were identified and documented, based on the stratified deposits of the selected rock shelters. The earliest phase of human occupation at the Bale Mountains is associated with a late Middle Stone Age assemblage at Fincha Habera rock shelter (3469 m asl). These Late Pleistocene occupations were connected with the extraordinary exploitation of a large rodent, the giant root-rat (Tachyoryctes macrocephalus). A total of 1026 lithic, around 2306 faunal remains, and 86 coprolite samples were analyzed to understand the late MSA cultural adaptations at the Bale Mountains. Excavations at Simbero and Mararo rock shelters also show that the high altitudes of the Bale Mountains were repeatedly occupied by LSA cultural groups from 15 to 2 ka cal. BP. While the Terminal Pleistocene settlements were represented by limited archaeological records, later hunter-gatherer occupations during the Middle and Late Holocene show a dramatic subsistence change in response to the high-altitude environments. The LSA cultural phase at these sites contains the lithic assemblages of around 6900 lithic artifacts and 1479 faunal remains. The latter include birds and fishes, and hint at the exploitation of a heterogeneous spectrum of wild animals. The lithic assemblages show a high frequency of microliths and additional tools classes such as borers, probably related to the subsistence to the high-altitude environments. Almost all lithic artifacts were made on locally available obsidian from the Wasama Ridge around the central Plateau of the Bale Mountains. The presence of a few exotic materials such as non-local obsidian and chalcedony in the lithic assemblages show the existence of regional contacts among hunter-gatherers in South and Southeastern Ethiopia. This study also suggests that the Bale Mountains lithic industries represent local specificities stone tool production as a long-term technological change in adapting to the high-altitude environments. Since the Bale Mountains complex was an open system, the typology and technology of the late MSA and LSA lithic assemblages show a notable technical similarity to the sites in the southern Ethiopian Rift Valley and the Southeastern Ethiopian Highlands. Based on the identified lithic composition and the technological changes, in association with the exploitation of abundant high-altitude resources including indigenous resources and raw material, the high-altitude regions of the Bale Mountains probably functioned as a paleoenvironmental refuge during environmental changes between OIS 3 to OIS 1. More archaeological data from the Arsi-Bale Mountain complex and other high-altitude regions are needed to support the contribution of this study.

Abstract:

The lakes of the eastern Africa Rift often contain great thicknesses of sediment that may provide continuous records of environmental change over decadal to million-year timescales. However interpretation of these changes is greatly compromised without a reliable chronology. Luminescence dating has not been used extensively in lacustrine settings; instead previous studies have often relied upon radiocarbon dating, using extrapolation beyond the upper limit of that technique, and employing opportunistic sampling of tephra and palaeomagnetic signatures where possible. This study from Lake Tana, Ethiopia, demonstrates that recent advances in luminescence methodology can provide long chronologies for lake sediments that are not dependent on the intermittent presence of dateable material, as is the case for radiocarbon and tephra-based methods. Specifically, this study generates luminescence ages that agree with independent chronology based on radiocarbon dating in the upper part of the core, and extends significantly beyond the range of radiocarbon dating to provide one of the longest independently dated lacustrine sediment records in eastern Africa, thus demonstrating the tremendous potential of luminescence for constructing lacustrine sediment chronologies over 100,000 year timescales.