Katharina Neumann

A new contribution to the Holocene vegetation history of the West African Sahel: pollen from Oursi, Burkina Faso and charcoal from three sites in northeast Nigeria

A pollen diagram from Oursi in Burkina Faso is compared with anthracological (charcoal analysis) results from three sites in northeast Nigeria (Konduga, Gajiganna, Lantewa). The present-day vegetation at all four sites is Sahelian or Sahelo-Sudanian and under heavy human impact. At Oursi, a closed grassland with only few trees and almost no Sudanian elements can be reconstructed for the middle Holocene. At the Nigerian sites, on the other hand, Sudanian woody plants were present during this period. We assume that the Sahel was not a uniform zone during the middle Holocene but rather a mosaic of different vegetation types according to local site conditions. In the light of these results, a simple model of latitudinally shifting vegetation zones is not applicable. Around 3000 B.P. the closed grassland at Oursi was opened by agro-pastoral activities, and at Gajiganna, plants characteristic of pasture lands can be directly related with the presence of cattle. Human impact seems to have been the dominant factor in the vegetation history of the Sahel from 3000 B.P. until today, masking possible effects of climatic change.

The emergence of pottery in Africa during the tenth millennium cal BC: new evidence from Ounjougou (Mali)

New excavations in ravines at Ounjougou in Mali have brought to light a lithic and ceramic assemblage that dates from before 9400 cal BC. The authors show that this first use of pottery coincides with a warm wet period in the Sahara. As in East Asia, where very early ceramics are also known, the pottery and small bifacial arrowheads were the components of a new subsistence strategy exploiting an ecology associated with abundant wild grasses. In Africa, however, the seeds were probably boiled (then as now) rather than made into bread.

Pits, Graves and Grains: Archaeological and Archaeobotanical Research in Southern Cameroun

Since 2003, a joint research project of the universities of Frankfurt and Tubingen (Germany) has explored the changing interrelationship of environment and culture in the forest-savanna regions of West and Central Africa. This paper provides the first archaeological and archaeobotanical results of three field seasons in the rainforest of southern Cameroun. Excavations were carried out at Bwambe Hill in the vicinity of Kribi at the Atlantic coast as well as at Akonetye, Minyin and Abang Minko’o, all located in the hinterland near Ambam. At all sites a number of pit structures, which contained mostly ceramics, were excavated. In addition, at Akonetye two graves with rich ceramic and iron offerings were unearthed. They seem to be the oldest graves with iron objects yet known in Central Africa.A large body of archaeobotanical material was retrieved from the structures excavated (charcoal fragments, charred fruits and seeds, phytolith and starch samples). Of high importance is the presence of pearl millet (Pennisetum glaucum) at Bwambe Hill and Abang Minko’o in archaeological contexts dated to about 2200 bp. Charcoal and pollen data indicate that the ancient settlements were situated in a closed rainforest which was, however, massively disturbed and partly substituted by pioneer plant formations.

Four thousand years of plant exploitation in the Chad Basin of northeast Nigeria I: The archaeobotany of Kursakata

This paper discusses archaeobotanical remains from the settlement mound of Kursakata, Nigeria, comprising both charred and uncharred seeds and fruits as well as charcoal. In addition, impressions of plant tempering material in potsherds were analysed. The late Stone Age and Iron Age sequence at Kursakata is date from 1000 cal. B.C. to cal. A.D. 100. DomesticatedPennisetum (pearl millet), wild Paniceae and wild rice are the most common taxa. Kernels from tree fruits were regularly found including large numbers ofVitex simplicifolia—a tree which is absent from the area today. A distinct change in plant spectra can be observed between the late Stone Age and the Iron Age. Although domesticated pearl millet was already known at the beginning of the settlement sequence of Kursakata, it only gained greater economic importance during the Iron Age. Besides farming, pastoralism and fishing, gathering of wild plants always played a major role in the subsistence strategy of the inhabitants of Kursakata. The charcoal results show that firewood was mainly collected from woodlands on the clay plains, which must have been more diverse than today. The end of the late Stone Age in the Chad Basin was presumably accompanied by the onset of drier environmental conditions from ca. 800 cal. B.C. onwards.

Early Plant Cultivation in the Central African Rain Forest: First Millennium BC Pearl Millet from South Cameroon

The Bantu expansion, a major topic in African archaeology and history, is widely assumed to correlate with the spread of farming, but archaeological data on the subsistence of these putative early Bantu speakers are very sparse. However, finds of domesticated pearl millet (Pennisetum glaucum) in southern Cameroonian archaeological sites, dated between 400 and 200 BC, open new perspectives on the history of agriculture in the Central African rain forest.Linguistic evidence suggests that pearl millet was part of early agricultural traditions of Bantu speakers, and has to a great extent been distributed during the course of their expansion over large parts of western Bantu-speaking Africa, possibly even originally from their homeland in the Nigerian-Cameroonian borderland.In combining archaeobotanical, palaeoenvironmental and linguistic data, we put forward the hypothesis that an agricultural system with pearl millet was brought into the rain forest during the first millennium BC, and that its spread across Central Africa coincided with the dispersal of certain Bantu language subgroups.

From Hunters and Gatherers to Food Producers: New Archaeological and Archaeobotanical Evidence from the West African Sahel

The relationship between language history, cultural development and environment in the West African savanna has been the focus of an interdisciplinary project at the University of Frankfurt (Germany) in co-operation with the Universities of Ouagadougou (Burkina Faso) and Maiduguri (Nigeria) since 1988 and Cotonou (Benin) since 1997. One major research question of the archaeological and archaeobotanical working groups is the transition from hunting and gathering to food production. Since the beginning of archaeological research in West Africa many local and interregional studies have dealt with this topic (e.g., Andah, 1987; Casey, 1998; Davies, 1968; Harris, 1976; Holl, 1998; McIntosh and McIntosh, 1988; Shaw, 1981; Smith, 1980; Sowunmi, 1985, 1999; Stahl, 1986, 1993). In most cases these papers were based on very limited direct evidence, as a multidisciplinary approach including archaeology, archaeozoology and archaeobotany had only been occasionally applied in Africa. Initially, our own point of view was colored by the European and Near Eastern evidence, i.e. the idea that sedentism, livestock keeping, agriculture and pottery appear synchronously as a ‘Neolithic package’. However, in the light of new research, the simultaneous emergence of Neolithic traits in Central Europe and the Mediterranean rather seems to be a unique case which cannot be transferred as a general model to other regions (see Harris, 1996) and apparently has no similarities with its West African counterpart. With an increasing amount of data it is becoming clear that even the West African version of the transition from hunting and gathering to food producing communities is quite heterogeneous. In this paper we would like to present two case studies from northern Burkina Faso (Prov. Oudalan) and from the Nigerian Chad Basin (Figure 9.1) which might illustrate the interregional variability in the West African Sahel zone.

The contribution of anthracology to the study of the late Quaternary vegetation history of the Mediterranean region and Africa

SummaryAnthracologlcal studies in the Mediterranean area and in Africa cover a time span of more than 40,000 years. Significant changes in the late Pleistocene and early Holocene charcoal spectra indicate large-scale climatic fluctuations. During the middle and late Holocene, the Mediterranean climax vegetation was transformed by human impact into various degraded formations. A detailed Holocene chronology has been established for the northwestern Mediterranean area. However, in the centre, the east and the south of the Mediterranean, anthracological studies are scarce and cannot be put together into a common framework. Regional chronologies exist for Italy, Algeria/Morocco and Israel. The first results from Africa demonstrate the contribution anthracology can make to the study of the vegetation history of desert, shrubland, savanna and rain forest under changing climatic conditions and anthropogenic influence.

Phytolith taphonomy in the middle- to late-Holocene fluvial sediments of Ounjougou (Mali, West Africa)

In semi-arid ecosystems where lacustrine sediments are rare, bio-proxies preserved in fluvial deposits are needed to understand environmental changes. In this study, we evaluate the potential of phytoliths as a bio-proxy in the Yamé River’s deposits at Ounjougou (Mali, West Africa) covering the middle to late Holocene (7790–4000 cal. BP). In soils, phytolith assemblages result mainly from decomposition of local vegetation but in alluvial deposits, the taphonomy of phytoliths is more complex, depending on the type of transport and deposition. In order to define the spatial origin of the phytolith assemblages, either from local (valley floor) or regional vegetation (catchment area), we took the sedimentary characteristics of the deposits into account. Using a combination of general and index approaches, phytoliths of 14 modern and 29 fossil samples from the Yamé valley were analyzed. The predominant source area of represented phytoliths varies with the fluvial energy of transport. Channel deposits, carried during periods of strong fluvial activity, contain higher numbers of savanna grass phytoliths and display a lower ratio of dicotyledon versus Poaceae phytoliths (D/P) than those deposited in the floodplain where phytoliths from the local gallery forest are more strongly represented. From the 5th millennium BP onwards, higher percentages of grass short cell phytoliths (GSCP) and lower D/P values point to gradual vegetation opening due to increasing aridity. High amounts of burned phytoliths show regular fire incidence in the gallery forest and attest for human impact on the landscapes of Ounjougou from the 7th millennium BP onwards. After 4500 cal. BP, there is evidence for pearl millet cultivation.

Early Plant Food Production in the West African Sahel

This paper presents new data from the project ‘Vegetation History and Archaeobotany of the West African Savannas’ at the University of Frankfurt, Germany, provided by palynology and the investigation of charcoal, fruits and seeds from archaeological sites. Our evidence from the Sahel in Burkina Faso and from north-east Nigeria indicates that agriculture started simultaneously in both areas around 3000 BP (c. 1200 BC) and that it was probably introduced from outside. The first pastoralists arriving in the Sahel zone of north-east Nigeria around 3700 BP (c. 2000 BC), depended wholly on wild grasses as a source of carbohydrates, and it was at least some hundreds of years before they added domesticated Pennisetum to their diet. Palynological data point to a major change towards drier conditions around 3300 BP which might have stimulated the introduction of agriculture into the Sahel. However, in some areas wild grasses remained the staple food until historical times.

The Palaeovegetation of Janruwa (Nigeria) and its Implications for the Decline of the Nok Culture

Settlement activities of the Nok Culture considerably decreased around 400 BCE and ended around the beginning of the Common Era. For a better understanding of the decline of the Nok Culture, we studied the charcoal assemblage of the post-Nok site Janruwa C, dating to the first centuries CE. Janruwa C differs from Middle Nok sites in ceramic inventory and a wider set of crops. 20 charcoal types were identified. Most taxa are characteristic of humid habitats such as riverine forests, while those savanna woodland charcoal types that had been dominant in Middle Nok samples are only weakly represented. The differences between the Middle Nok and post-Nok assemblages do not indicate vegetation change, but rather different human exploitation behaviors. It seems that the Nok people avoided forest environments while in the first centuries CE, other, possibly new populations settled closer to the forest and were more familiar with its resources. The new exploiting strategies might be explained as adaptation to changing environmental conditions. Our results, together with data from other palaeo-archives in the wider region, point to climatic change as a potential factor for the decline of the Nok Culture. We argue that erosion on the hill slopes, maybe due to stronger seasonality, was responsible for land degradation after 400 BCE and that the Nok people were not flexible enough to cope with this challenge through innovations.