Recycling of lithic artifacts, including both lithic scavenging and secondary recycling, is a widely recognized phenomenon in the Paleolithic archaeological record, in some instances creating tools with morphological signatures characteristic of multiple time periods or technological systems. These types of tools often define transitional industries including those at the Middle-to-Upper Paleolithic transition, suggesting a variety of behavioral interpretations for the supposed evolution of Middle Paleolithic toolkits to Upper Paleolithic toolkits. Here we test an alternative hypothesis that transitional assemblages formed via secondary recycling of stone artifacts produced by two technologically divergent populations. Results from the application of an agent-based model indicate how ordered sets of assemblages resembling archaeological transitional sequences can result from the combination of simple recycling behaviors and periods of sediment deposition and erosion. This implies that some transitional assemblages could have formed without the interaction of different populations and/or without technological evolution.

Analyses of ancient food webs reveal important paleoecological processes and responses to a range of perturbations throughout Earth's history, such as climate change. These responses can inform our forecasts of future biotic responses to similar perturbations. However, previous analyses of ancient food webs rarely accounted for key differences between modern and ancient community data, particularly selective loss of soft-bodied taxa during fossilization. To consider how fossilization impacts inferences of ancient community structure, we (1) analyzed node-level attributes to identify correlations between ecological roles and fossilization potential and (2) applied selective information loss procedures to food web data for extant systems. We found that selective loss of soft-bodied organisms has predictable effects on the trophic structure of “artificially fossilized” food webs because these organisms occupy unique, consistent food web positions. Fossilized food webs misleadingly appear less stable (i.e., more prone to trophic cascades), with less predation and an overrepresentation of generalist consumers. We also found that ecological differences between soft- and hard-bodied taxa—indicated by distinct positions in modern food webs—are recorded in an early Eocene web, but not in Cambrian webs. This suggests that ecological differences between the groups have existed for ≥48 Myr. Our results indicate that accounting for soft-bodied taxa is vital for accurate depictions of ancient food webs. However, the consistency of information loss trends across the analyzed food webs means it is possible to predict how the selective loss of soft-bodied taxa affects food web metrics, which can permit better modeling of ancient communities.

Recycling of lithic artifacts, including both lithic scavenging and secondary recycling, is a widely recognized phenomenon in the Paleolithic archaeological record, in some instances creating tools with morphological signatures characteristic of multiple time periods or technological systems. These types of tools often define transitional industries including those at the Middle-to-Upper Paleolithic transition, suggesting a variety of behavioral interpretations for the supposed evolution of Middle Paleolithic toolkits to Upper Paleolithic toolkits. Here we test an alternative hypothesis that transitional assemblages formed via secondary recycling of stone artifacts produced by two technologically divergent populations. Results from the application of an agent-based model indicate how ordered sets of assemblages resembling archaeological transitional sequences can result from the combination of simple recycling behaviors and periods of sediment deposition and erosion. This implies that some transitional assemblages could have formed without the interaction of different populations and/or without technological evolution.

Archaeologists typically define cultural areas on the basis of similarities between the types of material culture present in sites. The similarity is assessed in order of discovery, with newer sites being evaluated against older ones. Despite evidence for time-dependent site loss due to taphonomy, little attention has been paid to how this impacts archaeological interpretations about the spatial extents of material culture similarity. This paper tests the hypothesis that spatially incomplete data sets result in detection of larger regions of similarity. To avoid assumptions of cultural processes, we apply subsampling algorithms to a naturally occurring, spatially distributed dataset of soil types. We show that there is a negative relationship between the percentage of points used to evaluate similarity across space and the absolute distances to the first minimum in similarity for soil classifications at multiple spatial scales. This negative relationship indicates that incomplete spatial data sets lead to an overestimation of the area over which things are similar. Moreover, the location of the point from which the calculation begins can determine the size of the region of similarity. This has important implications for how we interpret the spatial extent of similarity in material culture over large distances in prehistory.

Interdisciplinary research is essential for the study of complex systems, and so there is a growing need to understand the factors that facilitate collaboration across diverse fields of inquiry. In this exploratory study, we examine the composition of self-organized project groups and the structure of collaboration networks at the Santa Fe Institute’s Complex Systems Summer School. Using data from all iterations of the summer school from 2005 to 2019, comprising 823 participants and 322 projects, we investigate the factors that contribute to group composition. We first test for homophily with respect to individual-level attributes, finding that group composition is largely consistent with random mixing based on gender, career position, institutional prestige, and country of study. However, we find some evidence of homophilic preference in group composition based on disciplinary background. We then conduct analyses at the level of group projects, finding that project topics from the Social and Behavioral Sciences are over-represented. This could be due to a higher level of baseline interest in, or knowledge of, social and behavioral sciences, or the common application of methods from the natural sciences to problems in the social sciences. Consequently, future research should explore this discrepancy further and examine whether it can be mitigated through policies aimed at making topics in other disciplines more accessible or appealing for collaboration.