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Human lifestyles vary enormously over time and space and so understanding the origins of this diversity has always been a central focus of anthropology. A major source of this cultural variation is the variation in institutional complexity: the cultural packages of rules, norms, ontologies and expectations passed down through societies across generations. In this article, we study the emergence of institutions in small-scale societies. There are two primary schools of thought. The first is that institutions emerge top-down as rules are imposed by elites on their societies in order to gain asymmetrical access to power, resources and influence over others through coercion. The second is that institutions emerge bottom-up to facilitate interactions within populations as they seek collective solutions to adaptive problems. Here, we use Bayesian networks to infer the causal structure of institutional complexity in 172 small-scale societies across ethnohistoric western North America reflecting the wide diversity of indigenous lifestyles across this vast region immediately prior to European colonization. Our results suggest that institutional complexity emerges from underlying socioecological complexity because institutions are solutions to coordination problems in more complex environments where human–environment interactions require increased management. [ABSTRACT FROM AUTHOR]

This study examines the fluting of two well‐known Late Pleistocene fluted point types in North America: Clovis and Folsom. Using scaling analyses, we assess the changing relationship between flute length and point length in a large sample of each type. Researchers use scaling to investigate the physical constraints of an object and determine how its dimensions change with size. We compare the strength and consistency of the scaling relationships between the older Clovis and the younger Folsom with the aim of shedding light on scaling differences, if any, over their temporal span. Our results show that there is a significant difference in the relationship of fluting length to point length between these types. In Folsom point manufacture, flute length increases nearly twice as fast with increasing point length than in Clovis. Importantly, the scaling of flute length to point length relationship is isometric (linear) in the Folsom sample, whereas it is allometric (sublinear) in the Clovis sample. In other words, Folsom flintknappers maintained a constant ratio of flute length to point length. Clovis flintknappers were less concerned about maintaining this ratio. We attribute this difference to a potentially increasing, or changing, functional role of fluting in Folsom. [ABSTRACT FROM AUTHOR]

Bullet ricochets are common occurrences during shooting incidents and can provide a wealth of information useful for shooting incident reconstruction. However, there have only been a small number of studies that have systematically investigated bullet ricochet impact site morphology. Here, this study reports on an experiment that examined the plan-view morphology of 297 ricochet impact sites in concrete that were produced by five different bullet types shot from two distances. This study used a random forest machine learning algorithm to classify bullet types with morphological dimensions of the ricochet mark (impact) with length and perimeter-to-area ratio emerging as the top predictor variables. The 0.22 LR leaves the most distinctive impact mark on the concrete, and overall, the classification accuracy using leave-one-out cross-validation is 62%, considerably higher than a random classification accuracy of 20%. Adding in distance to the model as a predictor increases the classification accuracy to 66%. These initial results are promising, in that they suggest that an unknown bullet type can potentially be determined, or at least probabilistically assessed, from the morphology of the ricochet impact site alone. However, the substantial amount of overlap this study documented among distinct bullet types' ricochet mark morphologies under highly controlled conditions and with machine learning suggests that the human identification of ricochet marks in real-world shooting incident reconstructions may be on occasion, or perhaps regularly, in error. Key points Bullet ricochet impact sites can help with shooting incident reconstruction. A random forest machine learning algorithm classified bullet type from ricochet morphology. Results suggest that unknown bullets can potentially be determined from ricochet impact site morphology. Human identification of bullet types from ricochet sites may be erroneous. [ABSTRACT FROM AUTHOR]

Researchers use a variety of target materials, and sometimes combinations of materials, in their archaeological experiments to examine thrust‐spear or projectile penetration, impact angle, durability, and other issues involving prehistoric hunting weaponry. This variety of target materials is beneficial to archaeological science in several ways, but it may also hinder the comparison of results because many of these target materials do not necessarily share similar physical properties. Here, we assess the penetration properties of four different target materials—store‐bought meat, clay, and two types of gelatin—via static penetration tests of a modern broadhead‐tipped arrow and a stone‐tipped projectile attached to an Instron Universal Materials Tester. Our analyses of load‐deflection curves, peak load, and work energy demonstrate how the four target materials are similar in some ways but different in others, which suggests that researchers may strategically employ one or several depending on the question asked or hypothesis tested. [ABSTRACT FROM AUTHOR]