New ages from Sehonghong rock shelter: Implications for the late Pleistocene occupation of highland Lesotho

Sehonghong rock shelter is situated in the eastern Lesotho highlands, a climatically extreme region of southern Africa. The site is one of a handful in southern Africa that preserves human occupations before, during, and after the Last GlacialMaximum(LGM). The site's long and well-preserved sequence makes it relevant to addressing questions of human mobility, subsistence, and technology in relation to broader environmental change. Here we present a Bayesian-modelled radiocarbon chronology for the LGM and terminal Pleistocene occupations at Sehonghong. Our model incorporates previously published radiocarbon dates and new accelerator mass spectrometry ages. We also present archaeological evidence to test the hypothesis that Sehonghong was occupied in a series of punctuated events, and that some of these occupations were more intensive than others. Previous chronological and archaeological data were insufficient for testing these hypotheses. The new dates and archaeological data confirmthat the sitewas occupied intensively in the early LGMand immediately thereafter. The site was otherwise occupied sporadically.We find that greater site occupation density is not always correlated with intensified use of local resources as measured by increased bipolar reduction and fish consumption. The new dates further confirm that Sehonghong contains some of the oldest evidence for systematic freshwater fishing in southern Africa. The availability of fish, a high fat protein source, probably stimulated human occupation, however sporadic, of suchmontane environments during cooler and drier periods. These findings suggest behavioural variability in response to shifting mobility and subsistence strategies. Our brief discussion informs upon huntergatherer occupation of southern Africanmontane environments more broadly and human behavioural variability during the LGM

Interpretative tools for studying Stone Age hunting technologies: experimental archaeology, macrofracture analyses and morphometric techniques

This dissertation contains an assessment and use of the macrofracture and morphometric methods for detecting Later Stone Age hunting weaponry. Two sets of replicated unretouched stone artefacts were trampled by cattle and humans to determine the formation of impact fractures under these, and knapping conditions. The results suggest that small frequencies (c. 3 %) of certain impact fracture types do occur on flakes subject to trampling and knapping forces. Macrofracture and morphometric data were recorded for stone artefacts (bladelets, backed artefacts and convergent pieces) from Robberg (c. 18 000 - 12 000 years ago) and Wilton (c. 8000 - 2000 years ago) Later Stone Age assemblages on the southern Cape coast. Impact fracture frequencies were similar in these two samples, but were significantly higher than in the trampling experiments. The morphometric data suggests, on average, congruence between Later Stone Age tools with impact fractures and experimental, archaeological and ethnohistoric spear and arrow tips. Based on these results it appears likely that Wilton backed artefacts, specifically segments, were used as arrowheads and it is unclear at present what weapon types were used during the Robberg phase although the use of spears seems probable

Assessing surface movement at Stone Age open-air sites : first impressions from a pilot experiment in northeastern Botswana

Open-air sites are ubiquitous signatures on most archaeological landscapes. When they are appropriately recorded, well-preserved and are single-component occupations, they provide access to high-resolution occupation data that is often not available from rock-shelter sites. These sites are, however, commonly affected by a number of post-depositional factors that are not adequately studied in archaeology. This paper presents the results of an open-air experiment conducted in northeastern Botswana. Two surface scatters modelled on known Bushman open-air camp sites were created to investigate the taphonomic factors affecting such sites. The scattered materials at these sites included stone tools, ostrich eggshell fragments, ceramic sherds, glass beads and faunal remains. Two scatters were laid out consisting of a nested square design; one site was excavated after four months and the other after twelve. The results show little horizontal material movement at these scatters and an initial, rapid, vertical period of mobility, after which the majority of surface artefacts are protected from subsequent movement, preserving the general scatter structures. This experiment suggests that open-air sites can offer detailed spatial information relevant to human settlement structure that is often not accessible at rock-shelter sites.Palaeontological Scientific Trust, the Leakey Foundation, the Meyerstein travel grant and Mashatu Game Reserve.http://www.sahumanities.org.za/hb201

Microfocus X-ray tomography as a method for characterising macro-fractures on quartz backed tools

Abstract: Here we present the first assessment of microfocus X-ray tomography (micro-XCT) as an analytical technique to generate data about macro-fractures on small quartz backed tools similar to those currently held to represent the oldest known evidence for bow hunting. Our experimental results are derived from 21 replicated quartz backed tools randomly selected from a population (n=218) that were broken in a controlled hunting context. We used 3D data obtained from micro-XCT scans to identify macro-fractures and to derive more accurate measurements for these fractures. Our results demonstrate that the micro-XCT technique overcomes reflected-light challenges associated with analysing quartz through conventional macro-fracture approache s. We were able to increase the total observed macrofracture sample by 33% compared with conventional approaches using a hand-lens. Whereas macro-fracture data could be refined, the additionally gained data did not change interpretations obtained from a conventional macro-fracture analysis. It did, however, marginally change the degree of significance in differences between the different applications. During this study, we also detected micro-fracture features, such as possible fracture wings and microscopic linear impact traces (MILTs).With further studies, the morphometric traits of these micro-fracture features could be useful for distinguishing between ancient weapon-delivery systems

Lithic miniaturization as adaptive strategy : a case study from Boomplaas Cave, South Africa

Abstract: Lithic miniaturization is a multivariate and evolutionarily significant technological phenomenon involving backed tools, bladelets, small retouched tools, flakes, and small cores. This paper investigates the proximate causes for variability in lithic miniaturization processes during Marine Isotope Stage 2 (c. 29–12 ka) in southern Africa. We test the hypothesis that lithic miniaturization represents a form of adaptive behavior by examining its relationship to site occupation intensity and rainfall seasonality at Boomplaas Cave in South Africa. These are two widely cited explanations for shifts in the organization of huntergatherer technologies and the data required for testing them are also readily available. We combine several lithic variables, macrofauna and microfauna indicators, and other archeological data to test the hypotheses. We find evidence that demographic processes impacted choices of technology within contexts of shifting rainfall seasonality, aridity, and rapidly rising Late Glacial sea-levels. In this context, Late Glacial humans converged on a small number of high payoff strategies including technological efficiency through bipolar bladelet production, greater production of ostrich eggshell ornaments and water containers, and a reorganized subsistence strategy targeting lower yield small mammals. The results demonstrate that lithic miniaturization was a strategic choice rather than an inevitable technological outcome. The outcomes have implications for understanding global instances of lithic miniaturization and their relationship to rapidly shifting paleoenvironments

New ages from Boomplaas Cave, South Africa, provide increased resolution on late/terminal Pleistocene human behavioural variability

Abstract: Boomplaas Cave, South Africa, contains a rich archaeological record, with evidence of human occupation from approximately 66,000 years ago until the protohistoric period. Notwithstanding a long history of research at the site, its existing chronology can benefit from revision. Many of the site’s members are currently delimited by only a single conventional radiocarbon date and some of the existing dates were measured on materials now known to be unsuitable for radiocarbon dating. Here we present the results of an ongoing effort to redate key late/terminal Pleistocene sequences in southern Africa. This paper presents a Bayesian-modelled radiocarbon chronology for the late/terminal Pleistocene horizons at Boomplaas. Our model incorporates previously published radiocarbon dates as well as new accelerator mass spectrometry ages. We also present archaeological evidence to examine in greater detail than was previously possible the nature of occupation patterning across the late/terminal Pleistocene and to assess technological change across two of the site’s Last Glacial Maximum (LGM) members. The new dates and archaeological data confirm that the site was occupied in a series of low intensity events in the early LGM and immediately thereafter. The site was occupied intensively in the terminal Pleistocene in line with major changes in palaeoenvironments and sea-level fluctuations. The lithic data show the use of variable technological strategies in contexts of shifting mobility and site occupation patterns. Our discussion informs upon huntergatherer behavioural variability that did not, and should not be expected to, reflect the strategies adopted and adapted by a handful of well-known arid-zone hunter-gatherers in the twentieth-century Kalahari

Modern thermoplastic (hot glue) versus organic-based adhesives and haft bond failure rate in experimental prehistoric ballistics

Abstract: The prehistoric production of composite technologies throughout human evolution was facilitated greatly by the use of adhesives. One such technology was projectile weaponry, which used adhesive to attach a stone point to a wooden shaft. Prehistoric projectile weaponry is often studied via experimental archaeology, which recreates ancient technologies to understand their manufacture and function. Here, we explore whether a modern thermoplastic adhesive can serve as a suitable replacement for two organic adhesives that would have been used by past peoples – pine resin and hide glue – in modern experimental tests of prehistoric weaponry. We conducted a ballistics experiment and shot groups of stone-tipped arrows, each group hafted with one of the three adhesives, and assessed the haft bond failure rate. The modern thermoplastic adhesive was similar to that of the pine resin and significantly failed less often than the hide glue. We conclude that in some cases modern thermoplastic adhesive can be substituted for organic-based adhesives in experimental archaeology. Our results also show that hafting bond failure rate was significantly different between the pine resin and the hide glue, suggesting that prehistoric hunter-gatherers faced costs or benefits in selecting adhesives for hafting

Comparative analysis of Middle Stone Age artifacts in Africa (CoMSAfrica).

Spatial and temporal variation among African Middle Stone Age (MSA) archeological assemblages provide essential cultural and behavioral data for understanding the origin, evolution, diversification, and dispersal of Homo sapiens—and, possibly, interactions with other hominin taxa. However, incorporating archeological data into a robust framework suited to replicable, quantitative analyses that can be integrated with observations drawn from studies of the human genome, hominin morphology, and paleoenvironmental contexts requires the development of a unified comparative approach and shared units of analysis. The CoMSAfrica workshop presented here, has the ambition to build bridges between researchers and research regions in Africa on these paramount topics

Miniaturization optimized weapon killing power during the social stress of late pre-contact North America (AD 600-1600)

Before Europeans arrived to Eastern North America, prehistoric, indigenous peoples experienced a number of changes that culminated in the development of sedentary, maize agricultural lifeways of varying complexity. Inherent to these lifeways were several triggers of social stress including population nucleation and increase, intergroup conflict (warfare), and increased territoriality. Here, we examine whether this period of social stress co-varied with deadlier weaponry, specifically, the design of the most commonly found prehistoric archery component in late pre-contact North America: triangular stone arrow tips (TSAT). The examination of modern metal or carbon projectiles, arrows, and arrowheads has demonstrated that smaller arrow tips penetrate deeper into a target than do larger ones. We first experimentally confirm that this relationship applies to arrow tips made from stone hafted onto shafts made from wood. We then statistically assess a large sample (n = 742) of late pre-contact TSAT and show that these specimens are extraordinarily small. Thus, by miniaturizing their arrow tips, prehistoric people in Eastern North America optimized their projectile weaponry for maximum penetration and killing power in warfare and hunting. Finally, we verify that these functional advantages were selected across environmental and cultural boundaries. Thus, while we cannot and should not rule out stochastic, production economizing, or non-adaptive cultural processes as an explanation for TSAT, overall our results are consistent with the hypothesis that broad, socially stressful demographic changes in late pre-contact Eastern North America resulted in the miniaturization–and augmented lethality–of stone tools across the region