The elusive archaeology of Kongo urbanism: the case of Kindoki, Mbanza Nsundi (Lower Congo, DRC)

We present here results, analyses and an in-depth historical contextualisation of the fieldwork undertaken in 2012 and 2013 at the Kindoki site in the Lower Congo (DRC). This site is linked with Mbanza Nsundi, one of the Kongo Kingdom's provincial capitals, which turns out to be archaeologically 'elusive'. Pinpointing its location proved to be particularly challenging. To this end, a historically-informed excavation methodology was developed that was never implemented in Central Africa before. We combined a strategy of systematic test pits with a large-scale 50 m grid approach. A cemetery was identified on Kindoki Hill with distinct but contemporaneous quarters of a 16th-17thcenturies settlement on both sides. The cemetery itself contains mainly 18th-century burials, in all likelihood of successive Nsundi rulers. The foreign, especially Portuguese, ceramics excavated on the hilltop and the hundreds of Venetian and likely Bavarian beads found in the graves are indicative of Mbanza Nsundi's connection to trade routes linking the Atlantic coast with the Pool region. The most striking discovery is that of a previously unknown type of comb-impressed pottery, from a pit with a calibrated radiocarbon date AD 1294-1393 (2 sigma). This suggests that a settlement had been developing at Kindoki since at least the 14th century, which allows us, for the very first time, to spatially bridge Kongo history and 'prehistory'. For the entire Lower Congo region only three 14C dates posterior to AD 1000 were available before the start of the KongoKing project, twelve have been added for just Kindoki

Cowries in the archaeology of West Africa: the present picture

Despite the perceived importance of cowrie shells as indicators of long-distance connections in the West African past, their distribution and consumption patterns in archaeological contexts remain surprisingly underexplored, a gap that is only partly explicable by the sparse distribution of archaeological sites within the sub-continent. General writings on the timeline of importation of cowries into West Africa often fail to take into account the latest archaeological evidence and rely instead on accounts drawn from historical or ethnographic documents. This paper is based on a first-hand assessment of over 4500 shells from 78 sites across West Africa, examining chronology, shell species and processes of modification to assess what distribution patterns can tell us about the history of importation and usage of cowries. These first-hand analyses are paralleled by a consideration of published materials. We re-examine the default assumption that two distinct routes of entry existed — one overland from North Africa before the fifteenth century, another coming into use from the time sea links were established with the East African coast and becoming predominant by the middle of the nineteenth century. We focus on the eastern part of West Africa, where the importance of imported cowries to local communities in relatively recent periods is well known and from where we have a good archaeological sample. The conclusion is that on suitably large assemblages shell size can be an indication of provenance and that, while the present archaeological picture seems largely to confirm historical sources, much of this may be due to the discrepancy in archaeological data available from the Sahara/Sahel zone compared to the more forested regions of the sub-continent. Future archaeological work will clarify this matter

Climate, history, society over the last millennium in southeast Africa

Climate variability has been causally linked to the transformation of society in pre-industrial southeast Africa. A growing critique, however, challenges the simplicity of ideas that identify climate as an agent of past societal change; arguing instead that the value of historical climate–society research lies in understanding human vulnerability and resilience, as well as how past societies framed, responded and adapted to climatic phenomena. We work across this divide to present the first critical analysis of climate–society relationships in southeast Africa over the last millennium. To achieve this, we review the now considerable body of scholarship on the role of climate in regional societal transformation, and bring forward new perspectives on climate–society interactions across three areas and periods using the theoretical frameworks of vulnerability and resilience. We find that recent advances in paleoclimatology and archaeology give weight to the suggestion that responses to climate variability played an important part in early state formation in the Limpopo valley (1000–1300), though evidence remains insufficient to clarify similar debates concerning Great Zimbabwe (1300–1450/1520). Written and oral evidence from the Zambezi-Save (1500–1830) and KwaZulu-Natal areas (1760–1828) nevertheless reveals a plurality of past responses to climate variability. These were underpinned by the organization of food systems, the role of climate-related ritual and political power, social networks, and livelihood assets and capabilities, as well as the nature of climate variability itself. To conclude, we identify new lines of research on climate, history and society, and discuss how these can more directly inform contemporary African climate adaptation challenges

Synergy of Key Properties Promotes Dendrimer Conjugates as Prospective Ratiometric Bioresponsive Magnetic Resonance Imaging Probes

Bioresponsive or smart contrast agents (SCAs) sensitive to Ca2+ are of extreme interest in the development of functional magnetic resonance imaging (MRI) techniques as they can aid in tracking neural activity in vivo. To this end, the design of macromolecular systems based on nanoscaffolds such as dendrimers functionalised with multiple MRI contrast agents have been used to conveniently increase the local concentration of paramagnetic MR reporters and slow the diffusion time of the probe, which are favourable in vivo characteristics. Moreover, previous studies with Ca-sensitive dendrimeric MRI probes revealed favourable properties crucial in the development of a ratiometric T2/T1-imaging method that provided a higher contrast-to-noise ratio compared to conventional T1- or T2-weighted imaging protocols. We therefore developed a series of novel dendrimeric MRI probes (DCAs) with differing structural properties and charge distributions. We thoroughly studied their features such as the relaxometric behaviour, size change and examined their electrostatic behaviours prior to and after the addition of Ca2+. The most active DCA displayed a common increase in r1 (3.11 mM-1 s-1 to 5.72 mM-1 s-1) and a remarkable increase in r2 (7.44 mM-1 s-1 to 34.57 mM-1 s-1), resulting in a r2/r1 ratio increase of the factor 2.52, which is greater than what was previously achieved. These changes in r1 and r2 were followed with a hydrodynamic diameter increase from 7.1 ± 1.2 to 8.5 ± 0.7 nm upon the addition of Ca2+, along with a decrease in the negative surface charge of the nanoparticle. Overall our findings indicate that highly responsive DCAs can be developed only through a combination of properties such as a change in hydration and size of the molecule, which come as a consequence of intramolecular structural and electrostatic changes in the particle. In turn, they provide a model for future preparations of responsive DCAs that can be utilized for both T1-weighted and ratiometric T2/T1-weighted imaging to visualize essential biological processes in a dynamic fashion