Cut marks on bone surfaces: influences on variation in the form of traces of ancient behaviour

Abstract

Although we know that our lineage has been producing sharp-edged tools for over 2.6 Myr, our knowledge of what they were doing with these tools is far less complete. Studies of these sharp-edged stone tools show that they were most probably used as cutting implements. However, the only substantial evidence of this is the presence of cut marks on the bones of animals found in association with stone tools in ancient deposits. Numerous studies have aimed to quantify the frequency and placement of these marks. At present there is little consensus on the meaning of these marks and how the frequency relates to specific behaviours in the past. Here we investigate the possibility that mechanical properties associated with edges of stone tools as well as the properties of bones themselves may contribute to the overall morphology of these marks and ultimately their placement in the archaeological record. Standardized tests of rock mechanics (Young's modulus and Vickers hardness) indicate that the hardness of tool edges significantly affects cut-mark morphology. In addition, we show that indentation hardness of bones also impacts the overall morphology of cut marks. Our results show that rock type and bone portions influence the shape and prevalence of cut marks on animal bones.

Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada

“…High resolution digital images of the median cross-section of suspected cut marks were captured and the depth, breadth and opening angle were measured using integrated tools. While these measurements are often used to describe the size of cut marks [46, 52, 57–59, 63, 64], the depth and breadth of a mark can greatly vary depending on the butchery action, carcass size or hardness of the bone surface [57, 58, 63]. Furthermore, the opening angle of a cut mark varies according to the attrition of the tool edge [59, 64].…”

“…While these measurements are often used to describe the size of cut marks [46, 52, 57–59, 63, 64], the depth and breadth of a mark can greatly vary depending on the butchery action, carcass size or hardness of the bone surface [57, 58, 63]. Furthermore, the opening angle of a cut mark varies according to the attrition of the tool edge [59, 64]. The breadth ratio (the ratio between the breadth at the top and the breadth at the bottom of the cut mark) [58] better illustrates the shape of the groove (\/ or |_|) and is a good criterion for distinguishing between cut marks made with stone tools and modifications produced by other effectors [44–46, 52, 58].…”

Experimental butchery study investigating the influence of timing of access and butcher expertise on cut mark variables

“…In his raw material ranking system based on replication experiments, Callahan (1979) suggests that flints are easier to work than argillite (see Braun, Plummer, Ferraro, Ditchfield, & Bishop, 2009 for more extensive discussion of stone tool raw material qualities based on physical properties). Although this study does not focus on the effect of raw material on cut mark morphology (e.g., Braun, Pante, & Archer, 2016;Greenfield, 2006;Maté-González et al, 2017), recent studies have found that the hardness of tool edges can affect cut mark morphology (Braun et al, 2016). Turning to the archaeological record, Braun et al (2009) found that hominins at Kanjera South, Kenya, were selecting raw materials to make Oldowan tools based on their durability (the ability of an edge to resist degradation by a static or dynamic force) rather than their fracture predictability (the consistency with which a particular type of stone fractures), and Stout, Quade, Semaw, Rogers, and Levin (2005) found that hominins at Gona preferred finer grained, phenocryst-poor materials for Oldowan toolmaking.…”

Flint and Quartzite: Distinguishing Raw Material Through Bone Cut Marks

“…Among those would be cut mark variability according to different types of carcasses, depending on animal size, animal age (regarding the hardness or fragility of cortical bone surfaces), the butcher's physical characteristics (different degrees of strength applied to cut‐marking) and/or the degree of wear‐use of lithics. Some of these variables have recently been tested by Braun et al (), who showed that the hardness of tool edges and the hardness of bones affect cut‐mark morphology. Here, we have documented different mark properties according to the raw material used.…”