The Palaeovegetation of Janruwa (Nigeria) and Its Implications for the Decline of the Nok Culture
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The Palaeovegetation of Janruwa (Nigeria) and its Implications for the Decline of the Nok Culture Alexa Höhn & Katharina Neumann Abstract Résumé Settlement activities of the Nok Culture considerably de- Les indices de peuplement de la culture Nok diminuent con- creased around 400 BCE and ended around the beginning of sidérablement aux alentours de 400 BC puis disparaissent the Common Era. For a better understanding of the decline au début de notre ère. Pour mieux comprendre son déclin, of the Nok Culture, we studied the charcoal assemblage of l’assemblage anthracologique du site Janruwa C, datant des the post-Nok site Janruwa C, dating to the first centuries CE. 1ers siècles CE, a été étudié. Le site diffère des sites Nok au Janruwa C differs from Middle Nok sites in ceramic inventory regard de l’inventaire des céramiques reconnu ainsi que par and a wider set of crops. 20 charcoal types were identified. une plus grande diversité des plantes cultivées. 20 types de Most taxa are characteristic of humid habitats such as river- charbons ont été identifiés. La plupart des taxons sont caracté- ine forests, while those savanna woodland charcoal types that ristiques d’habitats plus humides (ripisylve) alors que ceux de had been dominant in Middle Nok samples are only weakly la savane boisée, qui dominent les échantillons du Nok Moyen, represented. The differences between the Middle Nok and sont faiblement représentés à Janruwa C. La différence entre post-Nok assemblages do not indicate vegetation change, but les assemblages du Nok Moyen et du post-Nok ne présente rather different human exploitation behaviors. It seems that pas un changement de végétation mais plutôt une modification the Nok people avoided forest environments while in the first des modes d’exploitation. En effet, alors que les populations centuries CE, other, possibly new populations settled closer Nok ont évité les environnements forestiers, il semble que, to the forest and were more familiar with its resources. The durant les 1ers siècles CE, de nouvelles populations se soient new exploiting strategies might be explained as adaptation to installées à proximité et étaient plus familières avec les res- changing environmental conditions. Our results, together with sources forestières. L’émergence de ces nouvelles stratégies data from other palaeo-archives in the wider region, point d’exploitations peut être expliquée comme une adaptation to climatic change as a potential factor for the decline of the aux changements des conditions environnementales. Nos ré- Nok Culture. We argue that erosion on the hill slopes, maybe sultats, associés aux autres données paléoenvironnementales due to stronger seasonality, was responsible for land degrada- ouest-africaines, suggèrent un changement climatique comme tion after 400 BCE and that the Nok people were not flexible facteur potentiel à l’origine du déclin de la culture Nok. Nous enough to cope with this challenge through innovations. proposons ainsi que l’érosion des versants, peut-être en raison d’une saisonnalité croissante, soit responsable de la dégradation des terres après 400 BC et que les populations Nok n’étaient pas suffisamment adaptées pour faire face à ce défi par des innovations. Keywords: West Africa, archaeobotany, archaeological charcoal, vegetation history, human impact, climatic change Alexa Höhn 8 [email protected] / Katharina Neumann 8 [email protected] * Institute for Archaeological Sciences, African Archaeology & Archaeobotany, Goethe University, Norbert-Wollheim-Platz 1, 60629 Frankfurt a. M., Germany DOI 10.3213/2191-5784-10296 © Africa Magna Verlag, Frankfurt a. M. Published online 18 Nov 2016 Journal of African Archaeology Vol. 14 (3) Special Issue, 2016, pp. 331–353 331 This article is available under a Creative Commons Attribution 4.0 International License (CC BY 4.0) Downloaded from Brill.com10/10/2021 06:57:41PM via free access A. Höhn & K. Neumann Introduction sites nearby, Janruwa A and B, and with the results of previous investigations (Kahlheber et al. 2009). The The Nok Culture existed from the mid-second millen- most remarkable feature of Janruwa C is the presence nium BCE to around the turn of the Common Era in of fonio (Digitaria exilis Stapf) and of oil palm (Elaeis Central Nigeria, with settlement activities peaking dur- guineensis Jacq.), which had not been used during Mid- ing the Middle Nok phase between 900 and 300 BCE. dle Nok times (Kahlheber 2010). We hypothesize that Towards the end of this phase, the number of settlements the clear differences between the charcoal inventories of considerably decreased; according to radiocarbon dates, Janruwa C as opposed to Janruwa A and B and others only very few Late Nok sites have been found in the do not point to vegetation change, but instead to a shift research region (Franke & Breunig 2014; Franke of settlement sites from the hill slope to the valley floor, 2016). With the beginning of the Common Era, archaeo- next to the river. In the context of palaeoenvironmental logical sites with Nok attributes disappear completely. data from the wider region, we conclude that climatic New ceramic inventories, totally different in decoration, change might have been involved in the decline of the style and clay composition, and the absence of terracotta Nok Culture. figurines (Beck 2015; Franke 2015), in combination with a higher diversity of crops (Kahlheber 2010), point to a cultural change, possibly related to shifting The site and its environmental settings environmental conditions. Environmental settings Culture and environment seem to have been stable during Middle Nok times. There is no marked variation The core region of the Nok research project is located in the archaeological and archaeobotanical assemblages in the northern High Plains, the hilly foreland of the Jos of Middle Nok sites. For the production of the terracotta Plateau, northeast of the Nigerian capital of Abuja (Fig. figurines only very few clay sources were used (Beck 1). The relief is undulating with striking granite outcrops 2014, 2015). Stringent rules seem to have applied to and elevations between 300 and 900 meters. At Kafan- decoration and form of vessels in comparison to Early chan, a town about 60 km to the east of Janruwa C, mean and Late Nok pottery (Franke 2014). Throughout annual rainfall is about 1800 mm, mean monthly temper- Middle Nok times, subsistence was based on the same ature is 25°C and relative humidity averages about 63% crops and wild fruits: Pearl millet (Pennisetum glau- (Abaje et al. 2010). The rainy season lasts from April to cum (L.) R.Br.) was the most important crop, present October. If not cited otherwise the information on the in almost every site (Kahlheber et al. 2009) and cul- vegetation of the research area is derived from Keay tivated together with cowpea (Vigna unguiculata (L.) (1953), according to whom the region lies in the northern Walp.). The rarity of cowpea in the sites is probably part of the Southern Guinea vegetation zone of Nigeria. due to preservation problems. There is no evidence of Floristically it belongs to the Guinea-Congolia/Sudanian root or tuber crops. Endocarp fragments of Canarium regional transition zone (White 1983), with a mosaic schweinfurthii Engl. and Vitex sp., both with oleagi- of secondary (wooded) grassland, semi-evergreen rain nous seeds and edible mesocarp, have been found in forest and Isoberlinia woodland, the latter being typical many sites, but probably represent only a small part of of the Northern Guinea zone of Nigeria . Woodlands are the wild species collected for food (Kahlheber et al. open stands of trees at least 8 m tall with a canopy cover 2009). From the charcoal assemblages of Middle Nok of 40 % or more and a field layer usually dominated by sites, we assume that cultivation took place in a shifting high grasses; they are not true forests (White 1983). cultivation system with long fallow periods, and there The woodland is annually swept by fire and the degree is no evidence for erosion or land degradation. Prob- of canopy closure may vary, resulting in more and less ably the settlements shifted as well; this could explain open patches of savanna woodland. Gallery forests grow the surprisingly high number of archaeological sites along rivers, often specifically riverine species are found dispersed in the landscape (Rupp 2014). here tolerating periodical inundations. But also species of the lowland rainforest enter savanna regions along the What was the reason for the disappearance of the rivers. Gallery forests reach up to 600 m in width along Nok Culture, after having existed under stable condi- a major river (Porembski 2001), but are often narrower. tions and in a quite conservative manner for about In the vicinity of the Janruwa sites the watercourses are 1500 years? In this paper we explore the hypothetical small, and human pressure has reduced the gallery forests relationship between human impact, climate and veg- to small strips of at most several tens of meters width etation change and their implication for the decline of today. Species present at the Janruwa riverbank include the Nok Culture during the 4th century BCE, through Pandanus sp., Elaeis guineensis, Mitragyna sp., Ficus the study of charcoal samples from the post-Nok site sur Forssk. and Pterocarpus santalinoides DC. Light Janruwa C, dated to the 2nd to 4th century CE. We forests and dry forests are the two zonal forest types that compare the inventory with those of two Middle Nok are present in the Southern Guinea zone. These forests 332 Journal of African Archaeology Vol. 14 (3) Special Issue, 2016 Downloaded from Brill.com10/10/2021 06:57:41PM via free access The Palaeovegetation of Janruwa Figure 1. Central Nigeria. Location of Janruwa C and neighboring sites (Map: E. Eyub). benefit from humid soil conditions but do not tolerate ties of the sites pearl millet (Pennisetum glaucum) and flooding.