Bernhard Eitel

Climate change underlies global demographic, genetic, and cultural transitions in pre-Columbian southern Peru

Significance It has long been assumed that climate played a major role in the population history of the Central Andes. Although adaptations of the Andean populations to climatic changes such as the intensification of agriculture have been inferred from the archaeological record, evidence for demographic adaptations such as migration is missing so far. In this paper, ancient DNA data from populations that lived in southern Peru between 840 BC and 1450 AD provide evidence for two large-scale migrations in the Central Andes coincident with episodes of drought and increased climatic variability. These migrations led to a successive genetic homogenization of southern Peruvian populations generally attributed to intrusions by the late pre-Columbian highland empires such as the Wari, Tiwanaku, or Inca. Several archaeological studies in the Central Andes have pointed at the temporal coincidence of climatic fluctuations (both long- and short-term) and episodes of cultural transition and changes of socioeconomic structures throughout the pre-Columbian period. Although most scholars explain the connection between environmental and cultural changes by the impact of climatic alterations on the capacities of the ecosystems inhabited by pre-Columbian cultures, direct evidence for assumed demographic consequences is missing so far. In this study, we address directly the impact of climatic changes on the spatial population dynamics of the Central Andes. We use a large dataset of pre-Columbian mitochondrial DNA sequences from the northern Rio Grande de Nasca drainage (RGND) in southern Peru, dating from ∼840 BC to 1450 AD. Alternative demographic scenarios are tested using Bayesian serial coalescent simulations in an approximate Bayesian computational framework. Our results indicate migrations from the lower coastal valleys of southern Peru into the Andean highlands coincident with increasing climate variability at the end of the Nasca culture at ∼640 AD. We also find support for a back-migration from the highlands to the coast coincident with droughts in the southeastern Andean highlands and improvement of climatic conditions on the coast after the decline of the Wari and Tiwanaku empires (∼1200 AD), leading to a genetic homogenization in the RGND and probably southern Peru as a whole.

Man and Environment in the Eastern Atacama Desert (Southern Peru): Holocene Climate Changes and Their Impact on Pre-Columbian Cultures

Geoarchaeological evidence for Holocene palaeoclimates in the eastern Atacama desert is compiled to reconstruct the palaeoenvironmental history in the Andean foreland. In contrast to earlier assumptions that El Niňo events controlled the environment of pre-Columbian people in the Ica–Nazca region, major hydrological changes, triggered by oscillations of the summer monsoon in the western Andes, concurred with cultural changes.

Holocene environmental change in the Otjiwarongo thornbush savanna (Northern Namibia): evidence from soils and sediments

In the Otjiwarongo region (Northern Namibia), Vertisol–Kastanozem–Calcisol soil associations occur as patches of several hundred hectares in extent. They have formed in fine-grained Mid-Holocene sediments which accumulated on both sides of the subcontinental watershed between the Ugab River draining into the South Atlantic and the Omatako Omuramba draining into the Kalahari Basin. Kastanozem formation cannot be explained by the environments that exist at present. The humification suggests open savanna environments in the past and does not accord with the shrublands and thornbush savanna at present. Using AMS 14C and OSL data, it is possible to distinguish two periods of soil degradation during the recent past. Initially, most of the Kastanozems and Vertisols were buried by slope wash sediments to a depth of several decimetres. This process started in the mid-19th century at the latest. In a second phase, the soils were affected by rill and gully erosion, indicating increased runoff. This occurred during the last decades of the 19th and the first decades of the 20th century, probably as a result of intensified cattle farming. In contrast to other parts of Namibia, the prominent river channels of the Otjiwarongo region, most of them up to 20 m wide and 3–4 m deep, are a result of recent erosion. Degradation of vegetation and soils, and river channel formation, seem to be the main causes of farmland aridification.

Kulturentwicklung am Wüstenrand — Aridisierung als Anstoß für frühgeschichtliche Innovation und Migration

Trockengebiete nehmen derzeit fast 40 % der Festlandsflache der Erde ein und bieten uber 30 % der Weltbevolkerung Raum. Weite Teile der Trockengebiete unterliegen beschleunigten Transformationsprozessen, die vom globalen Klimawandel einerseits und von tiefgreifenden Eingriffen des Menschen in die Okosysteme andererseits verursacht sind (MEAR 2005). Verscharft wird die Lage durch das starke Bevolkerungswachstum (DSW 2006). Meist handelt es sich zudem um Agrargesellschaften, die sich neben Regen- und Bewasserungsanbau auf die Weidewirtschaft stutzen und damit besonders abhangig von den jeweils herrschenden Umweltbedingungen sind. Der rapide Umweltwandel trifft die Menschen existenziell, was durch die Tatsache unterstrichen wird, dass etwa 60 % aller Katastrophentoten in den Trockengebieten der Erde gezahlt werden (ISDR 2004).

Vulnerability of schools to floods in Nyando River catchment, Kenya

This paper assesses the vulnerability of schools to floods in the Nyando River catchment (3,600 km(2)) in western Kenya and identifies measures needed to reduce this vulnerability. It surveys 130 schools in the lower reaches, where flooding is a recurrent phenomenon. Of the primary schools assessed, 40% were vulnerable, 48% were marginally vulnerable and 12% were not vulnerable. Of the secondary schools, 8% were vulnerable, 73% were marginally vulnerable and 19% were not vulnerable. Vulnerability to floods is due to a lack of funds, poor building standards, local topography, soil types and inadequate drainage. The Constituencies Development Fund (CDF), established in 2003, provides financial support to cover school construction and reconstruction costs; CDF Committees are expected to adopt school building standards. In an effort to promote safe and resilient construction and retrofitting to withstand floods, this paper presents vulnerability reduction strategies and recommendations for incorporating minimum standards in the on-going Primary School Infrastructure Programme Design.

Palaeoenvironmental Transitions Between 22 ka and 8 ka in Monsoonally Influenced Namibia

The paper presents a preliminary reconstruction of the development of different palaeoenvironments between the Last Glacial Maximum (LGM; c. 22 - 18 ka) and the Holocene Altithermal (HA; c. 8 ka - 4 ka) in Namibia. The synopsis is based on 36 optical datations of dune sands and fine-grained, silty deposits (OSL and TL). Most of the data were published by different research groups during the last decade. The synoptic view of all available optical age determinations is necessary because palaeoclimatic interpretations for southwestern Africa are not possible using results based only on local studies and on partly unreliable datations (e. g. 14C ages of calcretes).

Built on Sand: Climatic Oscillation and Water Harvesting During the Late Intermediate Period

For the first time in South America, we found specific constructions for water harvesting from the Late Intermediate period. Their configuration allows the precise reconstruction of mean annual precipitation during that time. In that area, enhanced precipitation enabled the people to cultivate the desert. The remains of human occupation give evidence of a short climatic oscillation in the northern Atacama desert around ˜1300 AD.

Digital Geoarchaeology: An Approach to Reconstructing Ancient Landscapes at the Human-Environmental Interface

This paper aims to highlight the concept of digital archaeology, an approach to reconstructing ancient landscapes with special regard to human-environmental interactions. A broad variety of proper geoscientific, geo-informatic and archaeological methodologies is discussed, while special attention is paid to acquisition, quantity and quality of data as well as potentials and drawbacks of each application. Case studies from Central Crete demonstrate the particular suitability of remote sensing techniques, GIS-based analyses and landscape visualisations for this purpose. As shown by the results, digital geoarchaeological research provides access to new and hitherto unexplored datasets, which can be of great value for investigating archaeological questions. They shall not substitute profound archaeological expertise but support it in order to achieve a more comprehensive idea of palaeoenvironments. Digital geoarchaeology offers promising prospects for future studies combining geoscientific and humanistic know-how and constitutes a prosperous research field besides well-established physical geoarchaeology.

Understanding the Interactions between Climate Change, Landscape Evolution, Surface Processes and Tectonics in the Earth System: What Can the Studies of Chinese Deserts Contribute?

Due to large deserts on Earth surface a thorough understanding of climate change, landscape evolution and geomorphological processes having occurred in deserts is crucial for Earth System Science. The landscapes in deserts are, however, diverse and different over the globe with regard to their geomorphological nature, human activities and geological histories. In the last decades a great number of efforts have been put to the investigation of the initial timing of the occurrence of arid climate, e. g. in northwestern China. Silty sediments in the downwind directions have been used to deduce the histories of deserts. In general, there is a lack of knowledge about processes and landscapes in Chinese drylands between the initial Miocene silt sedimentation at desert margins and the late Quaternary multiple occurrences of wetter climate with assumed large lakes in many of the deserts in northern China. The geomorphological concept of three primary triggering factors, i.e., the sediment supply, sediment availability and transport capacity of wind, and additionally the underground geology need to be fully considered for a better understanding of the environmental histories of sand seas which should not be viewed as equivalent for deserts because sand seas cover between < 1% and ca. 45% of the desert areas in various continents dependent on a complex interaction between various processes of both exogenous and endogenous origins.

Fehlverhalten in der Forschung

Zu Guttenberg, Koch-Mehrin, Schavan – Plagiatsskandale schuren auch Zweifel an der Qualitatssicherung in der Forschung: Wie viel Tauschung durchzieht die Wissenschaft? Sind Abschreiben, Lug und Trug gar an der Tagesordnung? Und welche Gegenmasnahmen helfen? Ein Gesprach mit Bernhard Kempen, dem Vorsitzenden des Deutschen Hochschulverbands, und dem Rektor der Universitat Heidelberg, Bernhard Eitel.