Experimental lithic tool displacement due to long-term animal disturbance

Controlled experiments in lithic technology tend to focus on controlling the human component of lithic tool manufacturing and use; however, animal disturbance can move and alter artifacts in non-random ways, thus altering the behavioral meaning assigned to artifacts and their contexts. The patterning visible in archeological debris on a horizontal plane can provide evidence for activity zones, pathways, and site formation processes. While the effects of trampling actors on the vertical displacement of artifacts have shown that artifacts can be dramatically displaced, the horizontal movement due to trampling is relatively less studied, particularly the effect over extended time periods. Here, an experimental investigation of experimentally produced lithic tools in three contexts with varying degrees of animal trampling intensity is described, and the resulting patterns of artifact displacement are presented. Animal trampling can produce directed, non-random patterning in how artifacts are moved from their original location. The role that bedding slope plays in transport direction given different degrees of activity is also explored. These results show that trampling can produce patterned artifact scatters similar to activity centers and should be taken into consideration for spatial analyses of archeological formation processes

Comparing lithic assemblage edge damage distributions: examples from the late Pleistocene and preliminary experimental results

Drawing behavioral inferences from macroscopic edge damage observations on lithic assemblages relies on linking observed damage patterns to behavioral processes identified during experimentation. Such methods have proven useful. However, critics frequently cite equifinality between different processes and wear traces on individual artifacts as well as inconsistent inter-observer agreement as problems with a ‘low-powered approach’ to lithic use-wear. One potential source of information that has received less attention is the patterns of edge damage detectable at the assemblage scale. Such patterns are only discernable by quantification of the collective distribution and frequency of edge damage on individual specimens. Here we use GIS to digitize and spatially reference artifacts to standardize and quantify edge damage. We applied this method to an assemblage of Middle Stone Age convergent flakes from Pinnacle Point Cave 13B, South Africa (165 - 90 ka) and a series of experimental flakes recreated for several tasks including use in a calibrated crossbow experiment. Assemblage results indicate that archaeological patterns of edge damage are unlikely to have a taphonomic origin. Moreover, the patterning does not appear to result from use as hafted spear armatures. Our results demonstrate the statistical and interpretive power gained by assemblage analyses compared to individual artifacts. The additional benefit of including microwear and residue analysis using a single cohesive GIS recording framework will enable rapid dissemination of results between analysts and create a record of experimental and archaeological wear-traces available to other researchers

New experiments and a model-driven approach for interpreting Middle Stone Age Lithic Point Function using the Edge Damage Distribution Method

The Middle Stone Age (MSA) is associated with early evidence for symbolic material culture and complex technological innovations. However, one of the most visible aspects of MSA technologies are unretouched triangular stone points that appear in the archaeological record as early as 500,000 years ago in Africa and persist throughout the MSA. How these tools were being used and discarded across a changing Pleistocene landscape can provide insight into how MSA populations prioritized technological and foraging decisions. Creating inferential links between experimental and archaeological tool use helps to establish prehistoric tool function, but is complicated by the overlaying of post-depositional damage onto behaviorally worn tools. Taphonomic damage patterning can provide insight into site formation history, but may preclude behavioral interpretations of tool function. Here, multiple experimental processes that form edge damage on unretouched lithic points from taphonomic and behavioral processes are presented. These provide experimental distributions of wear on tool edges from known processes that are then quantitatively compared to the archaeological patterning of stone point edge damage from three MSA lithic assemblages--Kathu Pan 1, Pinnacle Point Cave 13B, and Die Kelders Cave 1. By using a model-fitting approach, the results presented here provide evidence for variable MSA behavioral strategies of stone point utilization on the landscape consistent with armature tips at KP1, and cutting tools at PP13B and DK1, as well as damage contributions from post-depositional sources across assemblages. This study provides a method with which landscape-scale questions of early modern human tool-use and site-use can be addressed

Lithic technological responses to Late Pleistocene glacial cycling at Pinnacle Point Site 5-6, South Africa

There are multiple hypotheses for human responses to glacial cycling in the Late Pleistocene, including changes in population size, interconnectedness, and mobility. Lithic technological analysis informs us of human responses to environmental change because lithic assemblage characteristics are a reflection of raw material transport, reduction, and discard behaviors that depend on hunter-gatherer social and economic decisions. Pinnacle Point Site 5-6 (PP5-6), Western Cape, South Africa is an ideal locality for examining the influence of glacial cycling on early modern human behaviors because it preserves a long sequence spanning marine isotope stages (MIS) 5, 4, and 3 and is associated with robust records of paleoenvironmental change. The analysis presented here addresses the question, what, if any, lithic assemblage traits at PP5-6 represent changing behavioral responses to the MIS 5-4-3 interglacial-glacial cycle? It statistically evaluates changes in 93 traits with no a priori assumptions about which traits may significantly associate with MIS. In contrast to other studies that claim that there is little relationship between broad-scale patterns of climate change and lithic technology, we identified the following characteristics that are associated with MIS 4: increased use of quartz, increased evidence for outcrop sources of quartzite and silcrete, increased evidence for earlier stages of reduction in silcrete, evidence for increased flaking efficiency in all raw material types, and changes in tool types and function for silcrete. Based on these results, we suggest that foragers responded to MIS 4 glacial environmental conditions at PP5-6 with increased population or group sizes, 'place provisioning', longer and/or more intense site occupations, and decreased residential mobility. Several other traits, including silcrete frequency, do not exhibit an association with MIS. Backed pieces, once they appear in the PP5-6 record during MIS 4, persist through MIS 3. Changing paleoenvironments explain some, but not all temporal technological variability at PP5-6.Social Science and Humanities Research Council of Canada; NORAM; American-Scandinavian Foundation; Fundacao para a Ciencia e Tecnologia [SFRH/BPD/73598/2010]; IGERT [DGE 0801634]; Hyde Family Foundations; Institute of Human Origins; National Science Foundation [BCS-9912465, BCS-0130713, BCS-0524087, BCS-1138073]; John Templeton Foundation to the Institute of Human Origins at Arizona State Universit

Frequency and distribution of edge damage on Middle Stone Age lithic points, Pinnacle Point 13B, South Africa

Unretouched convergent flakes are frequently a well represented tool type in many Middle Stone Age (MSA) assemblages. Damage to the lateral margins of these points is frequent; however, analytical methods for dealing with the frequency and distribution of edge damage on points have not been developed and applied to a complete MSA lithic assemblage. A method for using GIS to quantify edge damage and statistically analyze the relative location and frequency of edge damage is presented here and applied to the complete assemblage of MSA points from Pinnacle Point Cave 13B (PP13B), South Africa. The results indicate a frequency of edge damage consistent with heavier utilization of the dorsal surface over the ventral surface, and the left side over the right, with the dorsal left lateral margin being most heavily damaged. Additionally, the distribution of edge damage and low frequency of impact damage to the points suggest that PP13B represents a location where points were used for cutting activities and discarded. Applying the recording procedures advocated here to controlled edge damage replication experiments will help provide the interpretive linkages to site assemblage edge damage distributions

An experimental investigation of the functional hypothesis and evolutionary advantage of stone-tipped spears

Stone-tipped weapons were a significant innovation for Middle Pleistocene hominins. Hafted hunting technology represents the development of new cognitive and social learning mechanisms within the genus Homo , and may have provided a foraging advantage over simpler forms of hunting technology, such as a sharpened wooden spear. However, the nature of this foraging advantage has not been confirmed. Experimental studies and ethnographic reports provide conflicting results regarding the relative importance of the functional, economic, and social roles of hafted hunting technology. The controlled experiment reported here was designed to test the functional hypothesis for stone-tipped weapons using spears and ballistics gelatin. It differs from previous investigations of this type because it includes a quantitative analysis of wound track profiles and focuses specifically on hand-delivered spear technology. Our results do not support the hypothesis that tipped spears penetrate deeper than untipped spears. However, tipped spears create a significantly larger inner wound cavity that widens distally. This inner wound cavity is analogous to the permanent wound cavity in ballistics research, which is considered the key variable affecting the relative ‘stopping power’ or ‘killing power’ of a penetrating weapon. Tipped spears conferred a functional advantage to Middle Pleistocene hominins, potentially affecting the frequency and regularity of hunting success with important implications for human adaptation and life history

A stab in the dark: testing the efficacy of watsonia exudate as glue for stone tool hafting

Composite tool manufacture is a complex technological behaviour that arose in the Middle Stone Age. The hafting of stone tools to handles or shafts seems to depend on the use of glue or adhesive. Chemical and microscopic analysis of glue or adhesive residues on lithic artefacts show the origins of these residues to be from various plant and animal sources, although attributing these residues to specific species has been problematic for various reasons. Experimental evaluation of the efficacy of glue for composite tool manufacture is a valuable method to identify possible sources of residues found on lithic artefacts. Various plant sources of glue have been identified in historical accounts, but some are yet to be identified in the archaeological record or need to be tested for their efficacy. The botanical remains of the genus Watsonia are particularly well represented in the archaeological record, where it is thought to have been foraged as a food source by Stone Age hunter-gatherers. During field observations, Watsonia underground storage organs (USOs) have been found to produce exudate. We test the efficacy of this exudate as a hafting glue for stone tools. Our results indicate that Watsonia exudate is nearly as effective as resin from Vachellia karroo (previously Acacia karroo) trees. These results lay the groundwork for identifying glue as part of composite tool technological components in the archaeological record that may not yet have been identified by other analytical methods, and highlight the role USOs might have played in human technology

A model of hunter-gatherer skeletal element transport: the effect of prey body size, carriers, and distance

Zooarchaeologists frequently use the relative abundance of skeletal elements in faunal assemblages in conjunction with foraging theory models to infer subsistence decisions made by prehistoric hunter-gatherers. However, foraging models applied to ethnoarchaeological cases have had variable success linking skeletal transport decisions with foraging predictions. Here, we approach this issue with the well-known Hadza data to statistically model the skeletal element transport decisions in response to distance from the residential hub and the number of carriers available for carcass transport. We compare our modeling approach to the traditional skeletal element utility curves from Binford's work with the Nunamiut, and to the more recently proposed Shannon evenness measure. Our approach, based on standard yet powerful statistical modeling techniques, can help researchers gain increased insight into the prey part transport responses of hunter-gatherers. Our analyses treat individual prey skeletal elements by body size as the response variable. The results of this analysis suggest that utility curves, and the Shannon evenness approach as a proxy for utility curves, are problematic for making statements about prehistoric foraging from zooarchaeological data. Transport distance does not explain a significant portion of small prey (size class 2) skeletal element transport variation. However, distance explains a great deal of transport variation in large prey (size classes 4 and 5). Inferences from skeletal element profiles should be made relative to prey body size and the discard probability of individual elements. Understanding the influence of these variables allows construction of a framework for testing archaeological element profiles against ethnographically derived transport models

A quantitative analysis of wear distributions on Middle Stone Age marine shell beads from Blombos Cave, South Africa

Early archaeological evidence for symbolically-mediated behaviour, which is our ability to create and share coded information between and within groups, comes from the African Middle Stone Age. Nassarius kraussianus shell beads, discovered in the Late Pleistocene, Still Bay archaeological deposits at Blombos Cave, Western Cape, South Africa, are some of the worlds earliest personal ornaments and their discovery significantly pushed back the origins of complex human symbolling. Further analyses of these beads led to the hypothesis that stringing arrangements at Blombos Cave changed through time, with important implications for the development and maintenance of social norms and style in early human populations. This hypothesis was supported by qualitative comparisons of archaeological and experimental wear distributions. Here, we present the results of a quantitative approach, applying a modified edge damage distribution method and statistical modelling to published diagrams (Vanhaeren et al. 2013, Journal of Human Evolution 64, 500–517) of wear on N. kraussianus shell beads. Our results support the original findings that different beading arrangements result in different wear distributions, and that the wear distributions on Blombos Cave beads exhibit temporal variability. However, our results vary with respect to which stringing arrangements best match the archaeological samples. Furthermore, we conclude that a combination of multiple processes may best explain the archaeological wear distributions, a finding more congruent with a long and complicated life history of curated objects like beads. These findings add to a growing record of early human social behaviours, and contribute methodologically to use-wear analyses of personal ornaments recovered from the archaeological record