Bayesian Modeling of the Clovis and Folsom Radiocarbon Records Indicates a 200-Year Multigenerational Transition

Abstract

An enduring problem in North American archaeology concerns the nature of the transition between the Clovis and Folsom Paleoindian complexes in the West. Traditional models indicate a temporal hiatus between the two complexes implying that Folsom was a population replacement for Clovis. Alternatively, if Folsom was an innovation that occurred within Clovis populations and subsequently spread, we would expect to see a temporal overlap. Here, we test these hypotheses using high-quality radiocarbon dates and Bayesian statistics to infer the temporal boundaries of the complexes. We show that the Folsom complex initially appears between 12,900 and 12,740 cal BP, whereas Clovis disappears between 12,720 and12,490 cal BP. Therefore, Folsom may have appeared about 200 years before Clovis disappeared, and so the two complexes likely co-occurred in the West for nearly eight generations. This finding suggests that Folsom was a successful adaptive innovation that diffused through the western Clovis population, eventually going to fixation over multiple generations.

Comparing Clovis and Folsom fluting via scaling analysis

“…It is interesting to note that the findings we show here are consistent with recent research that suggests Folsom was an innovation that spread from a Clovis adaptation spreading over a period of nearly 2 centuries (Buchanan, Kilby, et al, 2022). Buchanan, Kilby, et al (2022) proposed that this change from Clovis to Folsom was probably the result of a new adaptation and a reconfiguration of the knowledge associated with hunting in a changed environment. In this work, Buchanan, Kilby, et al (2022) posited that Folsom was likely the consequence of an intentional search for a new optimal design solution.…”

“…Buchanan, Kilby, et al (2022) proposed that this change from Clovis to Folsom was probably the result of a new adaptation and a reconfiguration of the knowledge associated with hunting in a changed environment. In this work, Buchanan, Kilby, et al (2022) posited that Folsom was likely the consequence of an intentional search for a new optimal design solution. Thus, the reconfiguration of the Clovis point to the thinner and isometrically fluted Folsom point was one solution in a broader adaptive shift consistent with the overlap shown in Figure 3.…”

“…For example, (Thomas et al 2017; see also Story et al 2019) conducted a set of controlled experiments on Clovis fluted point forms that showed that flutes act to relocate damage to the point and thereby increase resiliency. But although fluting may have served to increase the resiliency of Clovis points, Folsom fluting may have been used to minimize the cross‐sectional profile of a point to increase point penetration (Buchanan & Hamilton, 2021; Eren, Bebber, Knell, et al, 2022; Hunzicker, 2005) at the expense of durability (see Buchanan, Kilby, et al, 2022). Therefore, in some contexts fluting might be an innovation in response to the need to minimize the profile of a point, whereas in other contexts it was an attempt to increase resiliency 2…”

“…Clovis is the oldest well documented fluted point type, which begins around 13,500 calibrated years before present (calBP) and lasts until about 12,500 calBP. Although the temporal span of the Clovis period based on the current sample of reliable dates may be closer to 500–870 years, or it could be longer than a millennium (Buchanan, Kilby, et al, 2022; Eren & Buchanan, 2016; Jennings & Smallwood, 2019; Prasciunas & Surovell, 2015; Waters et al, 2020). The proceeding Folsom period overlaps with Clovis for about 2 centuries beginning around 12,900–12,740 calBP and lasts 320–670 years, ending by approximately 12,300 calBP (Buchanan et al, 2021; Buchanan, Kilby, et al, 2022).…”

In situ evidence for Paleoindian hematite quarrying at the Powars II site (48PL330), Wyoming

“…Our modeled starting age estimate for component 1 of 12,840 to 12,505 cal B.P. overlaps with several estimates for the terminal age of Clovis ( 8 – 10 ), and our total occupation span overlaps entirely with age estimates for the Plainview (elsewhere “Goshen”) cultural complex ( 11 ). Component 1 was created during multiple occupations over a period of no less than 265 y.…”