Early anthropogenic impact on Western Central African rainforests 2,600 y ago.

A potential human footprint on Western Central African rainforests before the Common Era has become the focus of an ongoing controversy. Between 3,000 y ago and 2,000 y ago, regional pollen sequences indicate a replacement of mature rainforests by a forest-savannah mosaic including pioneer trees. Although some studies suggested an anthropogenic influence on this forest fragmentation, current interpretations based on pollen data attribute the ''rainforest crisis'' to climate change toward a drier, more seasonal climate. A rigorous test of this hypothesis, however, requires climate proxies independent of vegetation changes. Here we resolve this controversy through a continuous 10,500-y record of both vegetation and hydrological changes from Lake Barombi in Southwest Cameroon based on changes in carbon and hydrogen isotope compositions of plant waxes. [Formula: see text]13C-inferred vegetation changes confirm a prominent and abrupt appearance of C4 plants in the Lake Barombi catchment, at 2,600 calendar years before AD 1950 (cal y BP), followed by an equally sudden return to rainforest vegetation at 2,020 cal y BP. [Formula: see text]D values from the same plant wax compounds, however, show no simultaneous hydrological change. Based on the combination of these data with a comprehensive regional archaeological database we provide evidence that humans triggered the rainforest fragmentation 2,600 y ago. Our findings suggest that technological developments, including agricultural practices and iron metallurgy, possibly related to the large-scale Bantu expansion, significantly impacted the ecosystems before the Common Era.

Characterization and comparison of poorly known moth communities through DNA barcoding in two Afrotropical environments in Gabon 1.

Biodiversity research in tropical ecosystems-popularized as the most biodiverse habitats on Earth-often neglects invertebrates, yet invertebrates represent the bulk of local species richness. Insect communities in particular remain strongly impeded by both Linnaean and Wallacean shortfalls, and identifying species often remains a formidable challenge inhibiting the use of these organisms as indicators for ecological and conservation studies. Here we use DNA barcoding as an alternative to the traditional taxonomic approach for characterizing and comparing the diversity of moth communities in two different ecosystems in Gabon. Though sampling remains very incomplete, as evidenced by the high proportion (59%) of species represented by singletons, our results reveal an outstanding diversity. With about 3500 specimens sequenced and representing 1385 BINs (Barcode Index Numbers, used as a proxy to species) in 23 families, the diversity of moths in the two sites sampled is higher than the current number of species listed for the entire country, highlighting the huge gap in biodiversity knowledge for this country. Both seasonal and spatial turnovers are strikingly high (18.3% of BINs shared between seasons, and 13.3% between sites) and draw attention to the need to account for these when running regional surveys. Our results also highlight the richness and singularity of savannah environments and emphasize the status of Central African ecosystems as hotspots of biodiversity.

Population affinities in pre-colonial West Africa: The case of the burial cave Iroungou (Gabon, 14th-15th century CE).

INTRODUCTION: Our knowledge of the populations of sub-Saharan Africa in the periods before European colonization is limited. Few archeological sites containing human remains have been identified, and written sources for these periods are rare. The discovery in 2018 of the Iroungou sepulchral cave (Gabon), whose use predates the arrival of the Portuguese (14th-15th centuries CE), is an exceptional source of information: at least 28 individuals associated with numerous metal artifacts were found there. The anthropobiological remains were left in situ, but the eight best preserved crania were digitized. OBJECTIVES: This study focuses on the population affinities of these crania, whose morphology was described using 237 landmarks. MATERIALS AND METHODS: Geometric morphometric analyses were used to compare the eight Iroungou specimens with 154 individuals representing 12 well-defined African populations. After alignment (Generalized Procrustes Analysis), morphological affinity was assessed using Euclidean and Mahalanobis distances, and posterior probabilities of population membership (discriminant analysis). RESULTS: Results indicate that the eight Iroungou crania have, on average, more affinity with Bayaka Pygmy, followed by Central African Bantu. Nevertheless, individually, the Iroungou specimens show an important morphological variation and the eight crania can be separated into different affinity groups: Bayaka and Central African Bantu, KhoeSan, and East-African Bantu. Finally, one individual presents strong affinity with Somalis. CONCLUSION: This phenetic mapping of the Iroungou sample raises questions about the profile of the individuals deposited in the cave in a geographical area known for the Loango pre-colonial kingdom, which ruling class seemed to have had privileged relationships with the Pygmy populations.

INTRODUCTION: Nos connaissances sur les populations d'Afrique sub­saharienne des périodes précédant la colonisation européenne sont limitées. Peu de sites archéologiques contenant des restes humains ont été identifiés, et les sources écrites pour ces périodes sont rares. La découverte en 2018 de la grotte sépulcrale d'Iroungou (Gabon), dont l'utilisation remonte au XIVe­XVe siècles de notre ère, avant l'arrivée des Portugais, constitue une source d'information exceptionnelle: au moins 28 individus associés à de nombreux artefacts métalliques y ont été retrouvés. Les restes anthropobiologiques ont été laissés in situ, néanmoins, les huit crânes les mieux préservés ont été numérisés. OBJECTIFS: Cette étude s'intéresse aux affinités populationnelles de ces crânes, dont la morphologie a été décrite à l'aide de 237 points­repères répartis sur le massif facial supérieur et le calvarium. MATÉRIEL ET MÉTHODES: Des analyses par morphométrie géométrique ont permis de comparer les spécimens d'Iroungou avec 154 individus représentants 12 populations africaines bien définies. Après alignement des conformations (analyse Procrustes généralisée), l'affinité morphologique a été évaluée à l'aide des distances procrustes, euclidienne et mahalanobis, ainsi que des probabilités postérieures d'appartenance à une population (analyse discriminante). RÉSULTATS: Les résultats indiquent que les huit crânes d'Iroungou présentent en moyenne plus d'affinités avec les populations pygmées Bayaka, suivies des Bantus d'Afrique centrale. DISCUSSION: Cette affinité moyenne recouvre une réalité complexe: la population d'Iroungou est la plus hétérogène de notre échantillon et les huit crânes peuvent être séparés en différents groupes d'affinités: avec les Bayakas et les Bantus d'Afrique Centrale, les KhoeSan, et avec les Bantus d'Afrique de l'est. Enfin, un individu présente une affinité très forte avec les Somalis de notre échantillon. Cette cartographie phénétique de la population d'Iroungou interroge sur le profil des individus déposés dans la grotte dans une zone géographique connue le royaume précolonial Loango dont la classe dirigeante semble avoir eu des relations privilégiées avec les populations pygmées.

Analysis of Early Iron Age (2500 BP) and modern period (150 BP) starch grains in Western Central Africa.

Starch grain analysis carried out on 23 ceramic sherds from 6 refuse pits from the site of Nachtigal in central Cameroon is shedding light on a longstanding debate regarding ancient diets in Central Africa during the Iron Age (IA, 2500 years BP) but also more recently during the Modern Period (ca. 150 BP). The results indicate a varied, but balanced diet, consisting of cereals, legumes, oil-rich seeds, and tubers; the latter being very rarely documented in the region. Moreover, we underscore the presence of taxa still consumed today, or in recent times. Rescue archaeology, and the application of specialized methodologies, are critical to better nuancing past dietary practices in this region.

Climatic and cultural changes in the west Congo Basin forests over the past 5000 years.

Central Africa includes the world's second largest rainforest block. The ecology of the region remains poorly understood, as does its vegetation and archaeological history. However, over the past 20 years, multidisciplinary scientific programmes have enhanced knowledge of old human presence and palaeoenvironments in the forestry block of Central Africa. This first regional synthesis documents significant cultural changes over the past five millennia and describes how they are linked to climate. It is now well documented that climatic conditions in the African tropics underwent significant changes throughout this period and here we demonstrate that corresponding shifts in human demography have had a strong influence on the forests. The most influential event was the decline of the strong African monsoon in the Late Holocene, resulting in serious disturbance of the forest block around 3500 BP. During the same period, populations from the north settled in the forest zone; they mastered new technologies such as pottery and fabrication of polished stone tools, and seem to have practised agriculture. The opening up of forests from 2500 BP favoured the arrival of metallurgist populations that impacted the forest. During this long period (2500-1400 BP), a remarkable increase of archaeological sites is an indication of a demographic explosion of metallurgist populations. Paradoxically, we have found evidence of pearl millet (Pennisetum glaucum) cultivation in the forest around 2200 BP, implying a more arid context. While Early Iron Age sites (prior to 1400 BP) and recent pre-colonial sites (two to eight centuries BP) are abundant, the period between 1600 and 1000 BP is characterized by a sharp decrease in human settlements, with a population crash between 1300 and 1000 BP over a large part of Central Africa. It is only in the eleventh century that new populations of metallurgists settled into the forest block. In this paper, we analyse the spatial and temporal distribution of 328 archaeological sites that have been reliably radiocarbon dated. The results allow us to piece together changes in the relationships between human populations and the environments in which they lived. On this basis, we discuss interactions between humans, climate and vegetation during the past five millennia and the implications of the absence of people from the landscape over three centuries. We go on to discuss modern vegetation patterns and African forest conservation in the light of these events.