North American Clovis Point Form and Performance V: An Experimental Assessment of Spear Thrusting Penetration Depth and Entry Wound Size

ABSTRACTThis study is an assessment of Clovis spear thrusting penetration depth and entry wound size. This work is the fifth contribution in a series of experiments aimed at shedding light on the functional performance of distinct Clovis point forms. Here, using highly controlled and standardized procedures, we had a participant who had previously trained with bayonets and hand-to-hand combat thrust seven spears, each tipped with a distinct Clovis point form, into a ballistic gel target. Our statistical analysis of the 203 thrusts revealed, among several findings, that Clovis plan-view form does influence penetration depth and entry wound size. This result is consistent with the hypothesis that the functional selection of attributes could have contributed to Clovis point form variation.KEYWORDS: Clovislithic technologyexperimental archaeologyevolutionary archaeologyNorth America AcknowledgementsWe are appreciative to Julianne Taylor for taking photographs during the experiment. J.B., S.M., J.T., M.R.B., and M.I.E. are supported by the Kent State University College of Arts and Sciences, who generously provided the funding (to M.R.B.) for the ballistics gel in this experiment. We are also appreciative to editor Grant McCall and the three anonymous reviewers whose positive and constructive comments improved our manuscript.Disclosure StatementNo potential conflict of interest was reported by the author(s).Data Availability StatementThe authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.Notes1 In Eren et al. (Citation2023) we mistakenly reported two different knife handle diameters, one in the text (25.4 mm, i.e., one-inch), and one in Figure 1 (31.7 mm). The correct diameter is 25.4 mm.2 In light of their concluding paragraph (Pettigrew & Bamforth, Citation2023, p. 29), Pettigrew and Bamforth’s (Citation2023:, p. 28) criticism of our work regarding Clovis hunting of live mammoths (Eren et al., Citation2021, Citation2022c) makes little sense when their ballistics research involves dead bison. Based on their logic and published statements, holding these two animal types, and animation states, equal is “untenable” and “highly erroneous” (Pettigrew & Bamforth, Citation2023, p. 28, 29).3 Pettigrew et al. (Citation2023) suggest that kinetic energy (KE) and momentum can be better predictors of projectile penetration than TCSA/TCSP. We do not doubt this hypothesis and believe that it may be correct under specific conditions. Indeed, we have written that non-stone-point factors such as heavier darts or faster velocities “may even largely determine … penetration” (Eren et al., Citation2022c, p. 5). One issue worth mentioning here, however, is that at no point have we ever written that TCSA/TCSP were the predominant factors in projectile penetration. All we have written is that TCSA/TCSP correlates with penetration all else being equal (including KE, which in some circumstances should be equal). Thus, assuming future data re-analysis and experiments support Pettigrew et al.’s (Citation2023) results’ validity, there is nothing “troubling” (Pettigrew et al.’s, Citation2023, p. 21) about their findings regarding tip cross-sectional area. As such, Pettigrew et al.’s (Citation2023, p. 21) claim that their results are “most troubling” is a straw man: an increasingly common problem. For example, Mullen et al. (Citation2023) conducted an experiment comparing the penetration depths of bronze bilobate and trilobate points using bronze replicas. Following this, Pettigrew and Taylor (Citation2023) experimented using modern broadheads to discuss factors potentially influencing bronze point penetrability, such as armor. Although Pettigrew and Taylor (Citation2023) cite Mullen et al. (Citation2023), at no point do they mention that Mullen et al. (Citation2023) specifically and deliberately discuss the importance of testing armor in future experiments involving bronze bilobate and trilobate arrow tips. Pettigrew and Taylor (Citation2023:3) also incorrectly state that Mullen et al.’s (Citation2023) results led to “questions about why trilobate arrow points ever became popular in the ancient world”; in fact, Mullen et al. (Citation2023, pp. 4–5) discuss several potential factors for why trilobate points could have been adopted, explicitly acknowledge limitations of their study, and acknowledge the need for more experiments.4 Archaeologists have long noted the vibrant colors of many Clovis points (see Bebber, Citation2023 and references therein). Whilst speculating about Clovis point size as a warning signal to animal predators, it is perhaps worth pondering how chert colors may have served a similar purpose, akin to an animal like to the poison dart frog (e.g. Maan & Cummings, Citation2012). And regarding warning signals and weaponry, we also point the reader to the work of Fessler et al. (Citation2012).Additional informationFundingThis research was funded by the National Science Foundation - U.S. (NSF) [grant no 1649395, 1649406, 1649409]. M.I.E. and M.R.B. are supported by the Kent State University College of Arts and Sciences.