The extent to which Clovis peoples hunted proboscideans is debated. Convention requires that for a proboscidean butchery site to be accepted, contemporaneous artifacts must be spatially associated with faunal remains, and there must be evidence of use of the remains. Fourteen sites in North America currently meet those criteria; at least 31 do not. While these are reasonable requirements for avoiding false positives, such an approach risks identifying false negatives—rejecting spatial associations that are systemic associations. Given the known distributions of Clovis and proboscidean sites, how likely is it that artifacts are coincidentally associated with proboscidean remains? Conversely, how many spatial associations could be unrecognized butchery sites? To answer these questions, we simulated chance associations by plotting empirically informed densities and sizes of archaeological and proboscidean sites on simulated landscapes in which people and animals are (a) uniformly distributed and (b) tethered to water sources. The simulated frequencies of coincidental associations were compared to the observed frequency of co-occurrences. Our results suggest that of the 31 indeterminate empirical associations, at least 17 and as many as 26 are likely systemic associations, more than doubling previous estimates and revealing a greater role of humans in Pleistocene proboscidean exploitation than previously recognized.

A growing body of literature proposes that our ancestors contributed to large mammal extinctions in Africa long before the appearance of Homo sapiens, with some arguing that premodern hominins (e.g., Homo erectus) triggered the demise of Africa's largest herbivores and the loss of carnivoran diversity. Though such arguments have been around for decades, they are now increasingly accepted by those concerned with biodiversity decline in the present-day, despite the near complete absence of critical discussion or debate. To facilitate that process, here we review ancient anthropogenic extinction hypotheses and critically examine the data underpinning them. Broadly speaking, we show that arguments made in favor of ancient anthropogenic extinctions are based on problematic data analysis and interpretation, and are substantially weakened when extinctions are considered in the context of long-term evolutionary, ecological, and environmental changes. Thus, at present, there is no compelling empirical evidence supporting a deep history of hominin impacts on Africa's faunal diversity.

Mammoth (Mammuthus sp.) teeth are relatively abundant in Quaternary deposits from Eurasia and North America, and their isotopic compositions can be used to reconstruct past seasonal patterns in precipitation, diet, and migration. Strategies for collecting and interpreting such data, however, are strongly dependent on growth rates, which can vary among species, individuals, and within teeth. In this study, we use histological and isotopic measurements to determine enamel growth rates for a Columbian mammoth (Mammuthus columbi) tooth in two directions. Using histology, the growth rate through the enamel thickness (ET; perpendicular to the height of the tooth) is estimated at 0.8 to 1.5 mm/yr. Isotopic sampling through the innermost 0.36 mm of the ET recovered less than half a period of variation (i.e., half an inferred year of growth), which is consistent with the histological estimate for ET growth rate. A combination of histological and isotopic measurements suggests that the enamel extension rate (growth in the height of the tooth) is 13–14 mm/yr. Knowledge of enamel growth rates should improve the design and interpretation of future isotopic studies of mammoth teeth. The combination of histological and isotopic measurements may also prove useful in determining growth rates for other extinct taxa.