Using the radiocarbon dates of Central Africa for studying long-term demographic trends of the last 50,000 years: potential and pitfalls

ABSTRACT

This paper presents the first review of biases impacting Pleistocene and Holocene radiocarbon dates from Central Africa. Based on the pooling of the research expertise of the co-authors, twenty-four biases are listed, explained and documented and their impact on any radiocarbon date corpus demonstrated. To achieve this, a new corpus has been created of 1764 radiocarbon and TL assays from 601 archaeological sites published in the literature. Each date has been checked for its context. The irregular dynamics of research in space and time seriously impact the end result of previous analyses aiming to achieve a regional understanding of past demographic fluctuations. While peaks in the number of dates from the late Holocene seem to correspond to a positive demographic trend, it is suggested that the declines identified cannot be of any such use for the time being and that today’s picture does not presently support claims of a population “crash” at a regional or local level for any time period. The numbers are obscured by overall research deficits identifiable throughout the region. The maps of the dated sites presented offer good evidence of this and illustrate the vast expanses where no archaeological research has yet been carried out. The number of radiocarbon dates in Central Africa is more an indicator of the effort archaeologists have put into understanding a settlement than it is of ancient demographics. Successive waves of incoming people since c. 3500–3000 cal. BP, the two most important ones known since the 1990s, have created a cultural mosaic of coexisting technological groups. The last 40 years of research have revealed the inner complexity of these waves, some of which avoided parts of the region for centuries, thereby creating an irregular cultural mosaic of land use that is outlined by patterning in the radiocarbon dates.

RÉSUMÉ

Cet article présente la première étude des biais ayant un impact sur le corpus des dates radiocarbones du Pléistocène et de l’Holocène en Afrique centrale. Sur la base de la mise en commun de l’expérience des co-auteurs, vingt-quatre biais sont listés, expliqués, documentés, et leur impact sur le corpus de dates radiocarbone est démontré. Pour ce faire, un nouveau corpus est créé de 1764 analyses radiocarbone et TL provenant de 601 sites archéologiques publiés dans la littérature. Le contexte de chaque date a été vérifié. La dynamique irrégulière de la recherche dans l’espace et dans le temps a un impact sérieux sur le résultat final des analyses précédentes visant à obtenir une compréhension régionale de la démographie ancienne. Alors que les maximas dans le nombre de dates de la fin de l’Holocène semblent correspondre à une tendance démographique positive, on suggère que les déclins identifiés ne peuvent pas être d’une telle utilité pour le moment, et que le tableau actuel ne soutient pas les affirmations d'un “crash” de la population au niveau régional ou local pour n'importe quelle période de temps. Les chiffres sont obscurcis par les déficits globaux de recherche que identifiables dans toute la région. Les cartes des sites datés présentées ici en sont une bonne preuve et illustrent les vastes étendues où aucune recherche archéologique n’a encore été effectuée. Le nombre de datations radiocarbone en Afrique centrale est plus un indicateur des efforts déployés par les archéologues pour comprendre un site que de son ancienne démographie. Les vagues successives de populations depuis environ 3500 à 3000 ans avant le présent, les deux principales connus depuis les années 1990, ont créé une mosaïque culturelle de groupes technologiques coexistants dans l’espace. La recherche au cours de ces 40 dernières années a révélé la complexité interne de ces vagues, dont certaines ont évité certaines parties de la région pendant des siècles, créant ainsi une mosaïque culturelle et une utilisation irrégulière des terres mises en évidence par l’ensemble des dates radiocarbone.

KEYWORDS:

• Central Africa
• archaeology
• radiocarbon dates
• Pleistocene
• Holocene
• research biases

Acknowledgements

We thank Pierre de Maret, Philip de Barros, Isabel dos Santos, Mebus Geyh, Christine Hatté, the late Thomas Huffman, Emma Loftus, Christophe Mbida Mindzié, Julio Mercader and Maria Piedad de Jesus who read our manuscript and gave sound advice on how to improve it. The work of the four anonymous reviewers of the Journal is appreciated. All the research by Bernard Clist was funded from 2021 until March 2023 by the Fédération Générale du Travail de Belgique.

Additional information

Notes on contributors

Bernard Clist

Bernard Clist obtained his MA (1982) and PhD (2005) at the Université Libre de Bruxelles. His main research interest lies in the earliest villages of Central Africa, their social and economic dynamics and the analysis of their pottery. He has carried out and led archaeological research since 1983 in Zambia and Madagascar and in all the Central African countries, bar Congo-Brazzaville and the Central African Republic. He directed research on the Kongo kingdom between 2012 and 2016 — the first historical archaeology program in the region — and helped between 2015 and 2017 the Culture Ministry of Angola to have Mbanza Kongo added to UNESCO’s World Heritage List. He is currently a Research Assistant at the Institut des Mondes Africains in Paris, France and at the Centro de Investigaciones Cientificas y Tecnológicas in Malabo, Equatorial Guinea.

James Denbow

James Denbow is Professor Emeritus at the University of Texas at Austin, where he has taught for over 35 years. He received his PhD in 1983 from Indiana University and has conducted archaeological research in Malawi (1969 and 1972), Botswana (1976 to the present) and the Republic of Congo (1987 to 1991). From 1979 to 1986, he was Senior Curator at the National Museum of Botswana where he established and ran the Botswana Antiquities Program. His current research interest lies in seeking links between the earliest farming villages in west-central Africa and the first appearance of Bantu-speaking communities in southern Africa.

Raymond Lanfranchi

Raymond Lanfranchi taught archaeology at the Marien Ngouabi University in Brazzaville (Congo) from 1975 to 1986. He created and developed its Prehistory and Archaeology curriculum and obtained his PhD (1979) at the University of Paris I (France), on the theme of the prehistory of Congo. From 1986 to 2008, he was an expert in archaeology and cultural heritage, acting as head of various French funded medium-term cultural projects in Central and West Africa using the Fond d’Aide à la Coopération (FAC), specifically in Gabon, the Central African Republic, Bénin and Mauritania. While in Congo-Brazzaville, Gabon and the Central African Republic, he directed the MA and DES theses of several African students, carried out extensive archaeological fieldwork and published numerous papers.