Probing the Sources of Lithic Assemblage Variability: A Regional Case Study near the Homolovi Ruins, Arizona

This paper presents excavation results from Nyabusora, northern Tanzania, conducted by M. Posnansky and W.W. Bishop (1959) and M. Posnansky (1961). Only preliminary reports have previously been published. It synthesises the site’s history, incorporating previously unpublished analyses and information from Posnansky’s original field notes, and presents new 2014 field survey results and new archival research. Nyabusora holds particular significance as the only Early to Middle Stone Age (ESA/MSA) site in the region to have yielded both lithic and faunal remains, which gain new relevance in light of recent developments in ESA/MSA archaeology in eastern Africa. Nyabusora’s ‘Sangoan’ lithic assemblage is now largely decontextualised and associated finds have been lost, so this study presents the only available lithic and faunal analyses, alongside interpretations of the stratigraphic sequence and site. Such stratified assemblages are exceptionally rare and are generally attributed to the Middle Pleistocene. This research enhances understanding of Plio-Pleistocene landscape evolution in the Kagera River and western Lake Victoria-Nyanza Basin. It contributes important new data on ESA/MSA lithic variability and, via ongoing investigations by Basell within the Kagera catchment, offers huge potential for clarifying Middle Pleistocene palaeoenvironments.

The formation of lithic assemblages

This paper proposes a new methodology to study prehistoric lithic assemblages in an attempt to derive from that facet of prehistoric behavior the greater technoeconomic system in which it was embedded. By using volumetric artifact density and the frequency of retouched pieces within a given lithic assemblage, it becomes possible to identify whether these stone tools were created by residentially mobile or logistically organized foragers. The linking factor between assemblage composition and land-use strategy is that of curation within lithic assemblages as an expression of economizing behavior. This method is used to study eight sites from southeastern Italy to detect changes in adaptation during the Late Pleistocene. We compare and contrast Mousterian, Uluzzian, proto-Aurignacian and Epigravettian assemblages, and argue that the first three industries overlap considerably in terms of their technoeconomic flexibility. Epigravettian assemblages, on the other hand, display a different kind of land-use exploitation pattern than those seen in the earlier assemblages, perhaps as a response to deteriorating climatic conditions at the Last Glacial Maximum. While we discuss the implications of these patterns in the context of modern human origins, we argue that the methodology can help identify land-use patterns in other locales and periods.

This paper argues that there is a political, social, economic or even historical substratum to the location and development of settlement that is significant to the diachronic understanding of settlement systems but may easily get neglected in favour of discussions of settlement hierarchy or single events in settlement history. Hence, it postulates that the factors for initial site location may not be the same as the factors for further settlement development, and that said substratum should be explored to fully grasp the reasons behind settlement dynamics. In doing so, it focuses on two categories of sites - so-called bridge-sites at significant geographical locations and legionary garrisons turned colonies. Settlements used as examples are Horreum Margi, Naissus, Scupi, and Ratiaria in Moesia Superior.

Spatial correlation models of VS30 values: A case study of the Tehran region

The Hunter River is a source of mudstone and silcrete raw material utilised in the manufacture of stone implements in the Central Lowlands of the Hunter Valley. The innate differences in the physical properties of these materials provide a potential source for raw material variability in lithic assemblages. The aim of this study was to experimentally investigate this variability and identify any patterning. A limited survey of the Hunter River channel was undertaken to determine the occurrence of the materials. Samples were taken from two locations where both mudstone and silcrete occur in the gravel deposits. A controlled experiment was devised to objectively test the differences in the materials' physical properties, as expressed by their flakability and heat induced variation. To produce results in a consistent manner, and to eliminate subjective human input in the flaking process, a flaking machine was designed to simulate the human model of hard hammer percussion flaking. Also, similarly shaped rectangular cores were used. Experimental data suggests that the differences in the physical properties of the two materials can account for some of the variability in artefact form, and even assemblage variation. Heat treatment provided the Aboriginal stone worker with a lithic reduction strategy to effectively minimise the behaviour differentials of the two materials, and significantly enhance the flaking properties of one of the materials, silcrete. Experimentally heat treated mudstone and silcrete also exhibited macroscopically distinct colour change.

The Cys-loop ligand-gated ion channel superfamily is a major group of neurotransmitter-activated receptors in the central and peripheral nervous system. The superfamily includes inhibitory receptors stimulated by γ-aminobutyric acid (GABA) and glycine and excitatory receptors stimulated by acetylcholine and serotonin. The first part of this review presents current evidence on the location of the anesthetic binding sites on these channels and the mechanism by which binding to these sites alters their function. The second part of the review addresses the basis for this selectivity, and the third part describes the predictive power of a quantitative allosteric model showing the actions of etomidate on γ-aminobutyric acid type A receptors (GABA(A)Rs). General anesthetics at clinical concentrations inhibit the excitatory receptors and enhance the inhibitory receptors. The location of general anesthetic binding sites on these receptors is being defined by photoactivable analogues of general anesthetics. The receptor studied most extensively is the muscle-type nicotinic acetylcholine receptor (nAChR), and progress is now being made with GABA(A)Rs. There are three categories of sites that are all in the transmembrane domain: 1) within a single subunit's four-helix bundle (intrasubunit site; halothane and etomidate on the δ subunit of AChRs); 2) between five subunits in the transmembrane conduction pore (channel lumen sites; etomidate and alcohols on nAChR); and 3) between two subunits (subunit interface sites; etomidate between the α1 and β2/3 subunits of the GABA(A)R). These binding sites function allosterically. Certain conformations of a receptor bind the anesthetic with greater affinity than others. Time-resolved photolabelling of some sites occurs within milliseconds of channel opening on the nAChR but not before. In GABA(A)Rs, electrophysiological data fit an allosteric model in which etomidate binds to and stabilizes the open state, increasing both the fraction of open channels and their lifetime. As predicted by the model, the channel-stabilizing action of etomidate is so strong that higher concentrations open the channel in the absence of agonist. The formal functional paradigm presented for etomidate may apply to other potent general anesthetic drugs. Combining photolabelling with structure-function mutational studies in the context of allosteric mechanisms should lead us to a more detailed understanding of how and where these important drugs act.

Miniaturized stone tools made by controlled fracture are reported from nearly every continent where archaeologists have systematically looked for them. While similarities in technology are acknowledged between regions, few detailed inter-regional comparative studies have been conducted. Our paper addresses this gap, presenting results of a comparative lithic technological study between Klipfonteinrand and Sehonghong – two large rock shelters in southern Africa. Both sites contain Late Glacial (~18-11 kcal BP) lithic assemblages, though they are located in regions with different geologies, climates and environments. Results demonstrate that lithic miniaturization manifests differently in these different regions. Both assemblages provide evidence for small blade production, though key differences exist in terms of the specific technological composition of this evidence, the raw materials selected, the role played by bipolar reduction and the manner in which lithic reduction was organized. Patterned variability of this nature demonstrates that humans deployed miniaturized technologies strategically in relation to local conditions.

Abstract. In this paper, we introduce the usage of a newly developed spectral decomposition technique – combined maximum covariance analysis (CMCA) – in the spatiotemporal comparison of four satellite data sets and ground-based observations of aerosol optical depth (AOD). This technique is based on commonly used principal component analysis (PCA) and maximum covariance analysis (MCA). By decomposing the cross-covariance matrix between the joint satellite data field and Aerosol Robotic Network (AERONET) station data, both parallel comparison across different satellite data sets and the evaluation of the satellite data against the AERONET measurements are simultaneously realized. We show that this new method not only confirms the seasonal and interannual variability of aerosol optical depth, aerosol-source regions and events represented by different satellite data sets, but also identifies the strengths and weaknesses of each data set in capturing the variability associated with sources, events or aerosol types. Furthermore, by examining the spread of the spatial modes of different satellite fields, regions with the largest uncertainties in aerosol observation are identified. We also present two regional case studies that respectively demonstrate the capability of the CMCA technique in assessing the representation of an extreme event in different data sets, and in evaluating the performance of different data sets on seasonal and interannual timescales. Global results indicate that different data sets agree qualitatively for major aerosol-source regions. Discrepancies are mostly found over the Sahel, India, eastern and southeastern Asia. Results for eastern Europe suggest that the intense wildfire event in Russia during summer 2010 was less well-represented by SeaWiFS (Sea-viewing Wide Field-of-view Sensor) and OMI (Ozone Monitoring Instrument), which might be due to misclassification of smoke plumes as clouds. Analysis for the Indian subcontinent shows that here SeaWiFS agrees best with AERONET in terms of seasonality for both the Gangetic Basin and southern India, while on interannual timescales it has the poorest agreement.

This book examines the settlement patterns and intersite variability in lithic assemblages of Early Jomon (ca. 5000 BP) hunter-gatherers in Japan. A model is proposed that links regional settlement patterns and intersite lithic assemblage variability to residential mobility. The results of this study suggest that the Early Jomon people were not sedentary, as previously assumed, but instead moved their residential basis seasonally. The implications of this result are discussed in the context of the development of hunter-gatherer cultural complexity in general and the course of Japanese prehistory in particular.

Intensive archaeological survey of 14.5 sq km of the Upper Basin, an area located near the Grand Canyon's eastern South Rim in northern Arizona, has discovered 126 fire-cracked-rock piles that are surrounded by artifact scatters of varying size and assemblage composition. Because these phenomena are unprecedented in upland conifer ecosystems of the American Southwest, several hypotheses are explored regarding their formation histories. Analyses of artifact assemblages, botanical remains, pollen, and faunal remains recovered from four excavated sites indicate that they result from flaked-stone artifact production, ground-stone artifact reuse and recycling, ceramic-vessel-fragment recycling, and animal and plant processing. In addition, radiocarbon dates and temporally diagnostic projectile-points and ceramics imply that the sites differ in terms of frequency, intensity, and patterns of use, and with respect to the groups of people who formed them (Anasazi, Cohonina, Havasupai, or Hopi). Byproducts of a little-known, long-term land-use pattern in Southwestern prehistory (ca. A.D. 417–1650), these sites represent a key source of information for understanding how different sources of variability come to be expressed in archaeological landscapes.

The impact of deteriorating climatic conditions on variability in the archaeological record towards the Last Glacial Maximum (LGM) remains uncertain. Partly as a result of poor-quality data, previous studies on Upper Palaeolithic (UP) societies of North-Western Europe prior to the LGM have focused on techno-typological traditions and diversification to outline the diachronic processes through which assemblage composition changed. This study addresses the adaptive trade-offs brought about by the general climatic downturn towards the LGM in North-Western Europe, by investigating the impact of local climate and habitat characteristics on the behavioural variability that characterises Gravettian technological organisation compared to the previous Aurignacian, based on two assemblages from Walou Cave, Belgium. This site is one of the rare well-stratified sites in North-Western Europe with evidence for multiple occupation events accompanied by a fine-grained palaeoenvironmental record. We use a combination of analytical techniques (AMS, LA-ICP-MS and ZooMS) to evaluate questions about hunter-gatherer adaptations. Faunal remains at Walou Cave mirror the faunal diversity documented at numerous other Aurignacian and Gravettian sites in the broader European context, which is similar between both periods. The overall picture presented here, using multiple lines of evidence, is not entirely clear; nonetheless, the results suggest that Gravettian technologies are unlikely to solely be a product of heightened risk in relation to a significant reshuffling of food resources compared to the previous Aurignacian. Future research of the factors structuring assemblage variability prior to the LGM will have to assess whether Aurignacian and Gravettian technologies indeed offer no relative material advantage over one another, a phenomenon called ‘technological equivalence’.

Intertidal artificial habitats are proliferating, but are generally simpler in structure and host lower biodiversity than natural rocky reefs. Eco-engineering aims to enhance the biodiversity of coastal infrastructure, often through physical structural modifications that mimic topographic properties of natural shores. Relationships between biotic assemblages and structural properties of natural and artificial reefs have been extensively studied at sampling scales of up to 1 m2. But evidence that quantified local structural variation has an appreciable influence on biotic assemblages, at a shore-wide scale across regional environmental gradients, is lacking. Here we addressed this knowledge gap with an observational study at 32 natural and artificial intertidal reef sites in Wales, UK. We used multivariate community analysis and permutation tests to examine associations between local physical structure, regional environmental variables and sessile biotic assemblages. A potential influence of local habitat structure on assemblage composition was evident across regional-scale environmental gradients. Compared to natural sites, artificial reefs had lower taxonomic richness, distinct and more variable assemblage composition, and different physical structure. After removing the effect of habitat (natural or artificial), canonical correspondence analysis showed that environmental variables (wave exposure, sea surface temperature and salinity variation), along with two metrics of physical structure (standard deviation in log-transformed detrended roughness and skewness of surface verticality, both at 0.5 m scale), explained 40 % of the variation in assemblage composition among sites. The two structural metrics independently explained 14.5 % of the variation. Associations identified between individual taxa and environmental variables indicated that sites with a higher proportion of horizontal surfaces hosted more canopy macroalgae, which in turn support other algae and invertebrates. Our findings provide evidence to inform scaling-up of structural eco-engineering interventions from experimental contexts to enhance the biodiversity of coastal infrastructure across regional extents.

The mesosphere/lower-thermosphere/ionosphere (MLTI) region is a critical boundary in the coupling of the atmosphere, climate and space weather, however it is one of the least understood regions, making it hard to include in whole atmosphere models. The EISCAT radars at Tromsø (UHF and VHF) have been measuring ionospheric parameters, such as electron density, for almost 4 decades making them an excellent resource to study changes in the ionosphere over a long time period.  We have generated two data archives using 20 years of observations of EISCAT Tromsø from 2001 to 2021; the data have been re-analysed at 10-minutes and 1-hour integrations. These archives are used to study the different sources of variability in the MLTI from 50-200 km. This is the first time the mainland EISCAT data has been converted into a format that allows for long term statistical study. We have created electron density climatologies split by solar, geomagnetic and atmospheric indices to investigate the different drivers of variability in the MLTI region. We show seasonal averages of the electron density altitude profiles and compare our results to the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) and the Whole Atmosphere Community Climate Model.

The Oldowan site of Muhkai II, layer 80 (northeastern Caucasus): Spatial structure and cultural and chronological attribution of the lithic assemblage