Continent-wide or region-specific? A geometric morphometrics-based assessment of variation in Clovis point shape

Researchers have debated the existence of regional variation in Clovis points for over 60 years. Here, we report an attempt to resolve this argument using a large sample of Clovis points from dated assemblages and a suite of shape analysis methods known as geometric morphometrics. The study tested the two main hypotheses that have been put forward in the debate: the continent-wide adaptation hypothesis, which holds that Clovis points do not vary regionally, and the regional environmental adaptation hypothesis, which holds that there is regional variation as a consequence of Clovis groups adjusting their food-getting toolkits to local conditions. We used discriminant function analysis and a multivariate extension of the t test to assess whether differences in shape exist at two scales. The first set of analyses compared points from the most obvious environmental regions in North America, the East and the West. The second set of analyses investigated differences among points from subregions within the East and West. The analyses revealed significant differences between points from the East and the West and among points from some subregions. Follow-up analyses demonstrated that these differences are not the result of the most common confounding factors, raw material quality and resharpening. As such, the analyses support the regional environmental adaptation hypothesis rather than the continent-wide adaptation hypothesis. We conclude from this that Clovis people modified their points to suit the characteristics of local prey and/or the habitats in which they hunted.