For at least three million years, knapping stone has been practiced by hominin societies large and small, past and present. Thus, understanding knapping, knappers, and knapping cultures is fundamental to anthropological research around the world. Although there is a general sense that stone knapping is inherently dangerous and can lead to injury, little is formally, specifically, or systematically known about the frequency, location, or severity of knapping injuries. Toward this end, we conducted a 31-question survey of modern knappers to better understand knapping risks. Responses from 173 survey participants suggest that knapping injuries are a real and persistent hazard, even though a majority of modern knappers use personal protective equipment. A variety of injuries (lacerations, punctures, aches, etc.) can occur on nearly any part of the body. The severity of injury sustained by some of our participants is shocking, and nearly one-quarter of respondents reported having sought or received professional medical attention for a flintknapping-related injury. Overall, the results of this survey suggest that there would have likely been serious, even fatal, costs to knappers in past societies. Such costs may have encouraged the deployment of any social learning capacities possessed by hominins or delayed the learning or exposure of young infants or children to knapping.

Lithic technologies dominate understanding of early humans, yet natural processes can fracture rock in ways that resemble artefacts made by Homo sapiens and other primates. Differentiating between fractures made by natural processes and primates is important for assessing the validity of early and controversial archaeological sites. Rather than depend on expert authority or intuition, the authors propose a null model of conchoidally fractured Antarctic rocks. As no primates have ever occupied the continent, Antarctica offers a laboratory for generating samples that could only have been naturally fractured. Examples that resemble artefacts produced by primates illustrate the potential of ‘archaeological’ research in Antarctica for the evaluation of hominin sites worldwide.

Seeman, Morris, and Summers misrepresent or misunderstand the arguments we have made, as well as their own previous work. Here, we correct these inaccuracies. We also reiterate our support for hypothesis-driven and evidence-based research.

Archaeological collections are foundational to the discipline. Yet, researchers who study curated assemblages can face challenges. Here, we show how experimental archaeology can play a vital role in the interpretation of old archaeological collections. The Welling site, in Coshocton County, Ohio, is a multicomponent, stratified site with a substantial Clovis component in its lower levels. Using experimental flaked stone replication, we create an analog model of a “pure” Clovis bifacial debitage assemblage, as might be found at a lithic workshop. We predicted that if the Welling Clovis debitage assemblage was representative of a lithic workshop, then it would be similar to the experimental model. If the debitage assemblage was representative of a base camp, however, then it would be significantly different from the model because Clovis people would have been using, transporting, resharpening, rejuvenating, and recycling the debitage—all activities that would modify a “pure” Clovis bifacial debitage assemblage. Our statistical analyses supported the latter prediction. Overall, our study illustrates how productive the integration of experimental and archaeological data can be, and it emphasizes how important the curation and accessibility of both archaeological and experimental collections are to the discipline.

Stone was a critical resource for prehistoric hunter-gatherers. Archaeologists, therefore, have long argued that these groups would actively have sought out stone of ‘high quality’. Although the defining of quality can be a complicated endeavour, researchers in recent years have suggested that stone with fewer impurities would be preferred for tool production, as it can be worked and used in a more controllable way. The present study shows that prehistoric hunter-gatherers at the Holocene site of Welling, in Ohio, USA, continuously selected the ‘purest’ stone for over 9000 years.

It has long been assumed that Folsom points are more standardized than Clovis points, although an adequate test of this proposition has yet to be undertaken. Here, we address that deficiency by using data from a sample of Folsom and Clovis points recovered from sites across the western United States. We used geometric morphometric techniques to capture point shape and then conducted statistical analyses of variability associated with Clovis and Folsom point bases and blades. Our results demonstrate that Folsom bases and blades are less variable than those on earlier Clovis points, indicating an increase in point standardization during the Early Paleoindian period. In addition, despite published claims to the contrary, Clovis and Folsom point bases are no more variable than blades. Based on these results, we conducted additional analyses to examine the modularity and size of Clovis and Folsom points. The results suggest Clovis points have more integrated base and blade segments than Folsom points. We suggest that several classes of Clovis points—intended for different functions—might have been in use during the Clovis period and that the later Folsom points might have served only as weapon tips, the shape of which were constrained by the fluting process.

Identifying stone tool production techniques in the archaeological record can inform on prehistoric economy, time budgets, shared cultural practices, and the spatiotemporal occurrence of technological innovations and adaptations. The pressure flaking technique is one such innovation that appears on every continent Homo sapiens colonized. Pressure flaking has long been associated with the ability of flintknappers to produce small, regularly shaped flakes that were used to maintain particular edge shapes and resharpen dull tool edges with minimal loss of raw material. Despite the importance of pressure flaking, a method for supporting the identification of pressure flakes in the archaeological record is lacking. Here, we present a stone tool replication experiment that statistically compares flakes derived from bifacial pressure flaking and soft hammer percussion flaking. Our analyses show that pressure flakes are on average lighter, shorter, narrower, and thicker than soft hammer percussion flakes. Discriminant analyses indicate that pressure flakes can be correctly classified at a rate of 70 percent in a mixed sample. Furthermore, our findings validate the assumption that pressure flakes are less variable in form compared to soft hammer percussion flakes. Based on our results, we suggest quantitatively reevaluating the presence of pressure flaking in the global archaeological record.

Ronald Mason’s hypothesis from the 1960s that the southeastern United States possesses greater Paleoindian projectile-point diversity than other regions is regularly cited, and often assumed to be true, but in fact has never been quantitatively tested. Even if valid, however, the evolutionary meaning of this diversity is contested. Point diversity is often linked to Clovis “origins,” but point diversity could also arise from group fissioning and drift, admixture, adaptation, or multiple founding events, among other possibilities. Before archaeologists can even begin to discuss these scenarios, it is paramount to ensure that what we think we know is representative of reality. To this end, we tested Mason’s hypothesis for the first time, using a sample of 1,056 Paleoindian points from eastern North America arui employing paradigmatic classification and rigorous statistical tools used in the quantification of ecological biodiversity. Our first set of analyses, which compared the Southeast to the Northeast, showed that the Southeast did indeed possess significantly greater point-class richness. Although this result was consistent with Mason’s hypothesis, our second set of analyses, which compared the Upper Southeast to the Lower Southeast and the Northeast showed that in terms of point-class richness the Upper Southeast > Lower Southeast > Northeast. Given current chronometrie evidence, we suggest that this latter result is consistent with the suggestion that the area of the Ohio, Cumberland, and Tennessee River valleys, as well as the mid-Atlantic coastal plain, were possible initial and secondary “staging areas” for colonizing Paleoindian foragers moving from western to eastern North America.

Recently, advocates of an “older -than- Clovis” occupation of eastern North America have suggested that bi-pointed leaf-shaped lanceolate stone bifaces provide definitive evidence of human culture on the eastern seaboard prior to the Late Glacial Maximum. This argument hinges on two suppositions : first, that points of this form are exceedingly rare in the East and second, that all known occurrences of these point forms are from landforms or depositionaI environments dating to some time before the late Pleistocene. Neither of these suppositions is supported by the archaeological record. Bi-pointed leaf shaped blades have been recoveredfrom throughout the Middle Atlantic and Northeast, where they have been repeatedly dated, either radiometrically or by association with diagnostic artifacts, to between the Late Archaic and the Early Woodland. Statistical analysis of supposed “older-than-Clovis” leaf-shaped blades demonstrates that there are no significant differences in morphology between them and unequivocally Middle Holocene leaf-shaped blades. Until such time as evidence demonstrates otherwise, there is no reason to accept that these leaf-shaped bifaces are diagnostic of a Pleistocene, much less pre-Late Glacial Maximum, occupation in eastern North America.

The comments of Stanford and Bradley (above) do not address our criticisms and obfuscate the topic at hand with irrelevant data (e.g. the south-to-north movement of fluted points through the Ice Free Corridor), nonexistent data (e.g. ‘under the water’ or ‘destroyed sites’), and questionable data (e.g. Meadowcroft and Cactus Hill are by no means widely accepted, nor are Stanford and Bradley's ‘eight LGM sites’ in the mid-Atlantic region). Before touching on some of these points, we direct the reader to several recent articles (e.g. Morrow 2014; Raff & Bolnick 2014) that provide new evidence or arguments inconsistent with a trans-Atlantic migration, including the fact that DNA from the Clovis Anzick child (Montana) shows no European ancestry (Rasmussen et al. 2014). Although Stanford and Bradley describe their Solutrean ‘solution’ (Stanford & Bradley 1999) to the Pleistocene colonisation of North America as ‘testable’, their position is that the idea is correct until falsified. They propose that their colleagues have yet to provide sufficient ‘critiques’ or ‘challenges’ to discount it (see also Collins 2012; Collins et al. 2013). Yet they are the ones proposing a hypothesis inconsistent with overwhelming multidisciplinary evidence, and they ignore results of tests that do not support their claims.

Across Atlantic ice: the origin of America's Clovis culture (Stanford & Bradley 2012) is the latest iteration of a controversial proposal that North America was first colonised by people from Europe rather than from East Asia, as most researchers accept. The authors, Dennis Stanford and Bruce Bradley, argue that Solutrean groups from southern France and the Iberian Peninsula used watercraft to make their way across the North Atlantic and into North America during the Last Glacial Maximum (LGM). According to Stanford and Bradley, this 6000km journey was facilitated by a continuous ice shelf that provided fresh water and a food supply. Across Atlantic ice has received a number of positive reviews. Shea (2012: 294), for example, suggests that it is “an excellent example of hypothesis-building in the best tradition of processual archaeology. It challenges American archaeology in a way that will require serious research by its opponents”. Runnels (2012) is equally enthusiastic.

The notion that Paleoindians used bifaces as “mobile cores” is widespread in Late Pleistocene lithic research, although it can be difficult to test empirically. Here, we use experimental replication to establish two quantitative predictions that would be indicative of biface-core transport. If bifaces are being used as mobile cores, then we should see among a group of sites of varying toolstone procurement distances (a) a negative relationship between toolstone procurement distance and the mean unifacial tool maximum-thickness value from each site; and (b) a negative relationship between toolstone procurement distance and the variability (standard deviation) of maximum flake thickness values from each site. We then test these predictions against data from six Clovis sites of varying toolstone procurement distance in the Lower Great Lakes region. The results show that both sets of data possess a strong, positive relationship with increasing toolstone procurement distance, which is inconsistent with the notion that biface-cores were transported. Since the Clovis presence in the Lower Great Lakes is widely acknowledged to be a colonization pulse, we conclude that the lack of biface-core transport there is an economizing and risk-mitigating behavior consistent with the models of Kuhn (1994) and Meltzer (2002, 2003, 2004).

It has been proposed that Paleolithic studies should abandon their focus on groups and turn instead to the individual. If individuals are to emerge from the lithics-dominated Middle Paleolithic record, the best chance of success is to identify the products of learner knappers from those of their mentors. To do so we need a framework of knapping standards by which to measure Middle Paleolithic skill level. Selected measurements on a sequence of 100 subcircular Levallois tortoise core reductions by a knapper of intermediate skill were compared with 25 reductions by his highly experienced instructor. Four measures emerge as potential markers of skill level: total stone consumption during initial core preparation, consumption from the upper and lower core surface, symmetry of the first detached Levallois flake, and failure rate of that detachment by overshooting the core's rim. These markers allow us to discriminate between the work of a modern learner and his mentor, but > 30 percent were misclassified. The learning trajectory is more complex than the mere honing of skills through practice and is punctuated by increasing numbers of mentor-like reductions. It follows that skill-level measures on their own are imperfect discriminators. Personal markers other than those of skill level must be found by which to seek individuals in the Middle Paleolithic record.