2,795 research outputs found
Steps towards operationalizing an evolutionary archaeological definition of culture
This paper will examine the definition of archaeological cultures/techno-complexes from an evolutionary perspective, in which culture is defined as a system of social information transmission. A formal methodology will be presented through which the concept of a culture can be operationalized, at least within this approach. It has already been argued that in order to study material culture evolution in a manner similar to how palaeontologists study biological change over time we need explicitly constructed âarchaeological taxonomic unitsâ (ATUs). In palaeontology, the definition of such taxonomic units â most commonly species â is highly controversial, so no readily adoptable methodology exists. Here it is argued that âcultureâ, however defined, is a phenomenon that emerges through the actions of individuals. In order to identify âculturesâ, we must therefore construct them from the bottom up, beginning with individual actions. ChaĂźne opĂšratoire research, combined with the formal and quantitative identification of variability in individual material culture behaviour allows those traits critical in the social transmission of cultural information to be identified. Once such traits are identified, quantitative, so-called phylogenetic methods can be used to track material culture change over time. Phylogenetic methods produce nested hierarchies of increasingly exclusive groupings, reflecting descent with modification within lineages of social information transmission. Once such nested hierarchies are constructed, it is possible to define an archaeological culture at any given point in this hierarchy, depending on the scale of analysis. A brief example from the Late Glacial in Southern Scandinavia is presented and it is shown that this approach can be used to operationalize an evolutionary definition of âcultureâ and that it improves upon traditional, typologically defined technocomplexes. In closing, the benefits and limits of such an evolutionary and quantitative definition of âcultureâ are discussed
Anatomical bases of sex- and size-related acoustic variation in herring gull alarm calls
The hypothesis that anatomical or physiological factors can constrain the production of vocalizations is supported by an increasing number of examples from a range of taxa, where acoustic variation is related to sex, body-size or condition. In this study, we combine anatomical and acoustic investigations in herring gulls Larus argentatus to 1) identify co-variation between sex, body size and the dimensions of the vocal apparatus and 2) test the possible effect of this co-variation on interindividual variation in the acoustics of alarm calls. We found that the vocal apparatus was sexually dimorphic, with males having longer trachea and bigger vibratile membranes than females. We also identified a relationship between the headâbill length â a secondary sexual trait â and the length of the trachea in males only. However, we failed to identify corresponding sex- and body-size related variation in the acoustic components of alarm calls. We suggest that this absence of a relationship between anatomical and acoustic dimensions may reflect the lack of biomechanical constraints exerted during the production of alarm calls, and that such relationships are more likely to be expressed in this speciesâ sexual calls, whose production is characterised by more pronounced, ritualised postures that are more likely to highlight inter-individual size variation
Climate and Demography in Early Prehistory: Using Calibrated 14C Dates as Population Proxies
Although difficult to estimate for prehistoric hunter-gatherer populations, demographic variablesâpopulation size, density, and the connectedness of demesâare critical for a better understanding of the processes of material culture change, especially in deep prehistory. Demography is the middle-range link between climatic changes and both biological and cultural evolutionary trajectories of human populations. Much of human material culture functions as a buffer against climatic changes, and the study of prehistoric population dynamics, estimated through changing frequencies of calibrated radiocarbon dates, therefore affords insights into how effectively such buffers operated and when they failed. In reviewing a number of case studies (Mesolithic Ireland, the origin of the Bromme culture, and the earliest late glacial human recolonization of southern Scandinavia), I suggest that a greater awareness of demographic processes, and in particular of demographic declines, provides many fresh insights into what structured the archaeological record. I argue that we cannot sideline climatic and environmental factors or extreme geophysical events in our reconstructions of prehistoric culture change. The implications of accepting demographic variability as a departure point for evaluating the archaeological record are discussed
Non-linear optical frequency conversion crystals for space applications
Reliable, long term operation of high-power laser systems in the Earth orbit is not a straightforward task as the space environment entails various risks for optical surfaces and bulk materials. The increased operational risk is, among others, due to the presence of high energy radiation penetrating the metallic shielding of satellites and inducing absorption centers in the bulk of optical components, and vacuum exposure which can deteriorate coating performance. Comprehensive testing for analyzing high-energy radiation effects and mitigation procedures were performed on a set of frequency conversion crystals and are discussed in this paper. In addition to a general resistance to space environmental effects, the frequency conversion crystals were subjected to a comparative analysis on optimum third harmonic efficiency, starting from pulsed 1064 nm laser radiation, with the goal of exceeding a value of 30 %. Concomitant modeling supported the selection of crystal parameters and the definition of crystal dimensions
Redeveloping Homeless History and Chronicity Documentation: A Study for Heartland Family Service
In recent months, the Permanent Supportive Housing (PSH) program at Heartland Family Service (HFS) has seen substantial delays during their intake process, specifically when it comes to verifying a clientâs HUD-required homeless history. This has led to an increase in program vacancies, fewer clients served, and an underutilization of the programâs budget, which could also induce more permanent defunding in the future. While the agency is working to address this problem by retraining all of their case managers on how to collect homeless histories, this project seeks to instead identify and address the problem through the case managersâ perspective. Through a survey of Heartlandâs housing case managers (n=20), it was determined that the biggest barrier to completing accurate homeless histories was not a lack of understanding from the case managers but a result of the process for acquiring the histories, as well as the clientsâ lack of memory regarding their own whereabouts. As a result, this project proposes three alternative ways to address this problem- include the use of a visual aid in the collection process, recommunicate current policy and establish new standards for preparing information beforehand, and move the collection of homeless histories from intake to another meeting for programs that do not require it for eligibility purposes
Tangled Trees: Modelling Material Culture Evolution as Host-Associate Co-Speciation
Book description: This volume offers an integrative approach to the application of evolutionary theory in studies of cultural transmission and social evolution and reveals the enormous range of ways in which Darwinian ideas can lead to productive empirical research, the touchstone of any worthwhile theoretical perspective. While many recent works on cultural evolution adopt a specific theoretical framework, such as dual inheritance theory or human behavioral ecology, Pattern and Process in Cultural Evolution emphasizes empirical analysis and includes authors who employ a range of backgrounds and methods to address aspects of culture from an evolutionary perspective. Editor Stephen Shennan has assembled archaeologists, evolutionary theorists, and ethnographers, whose essays cover a broad range of time periods, localities, cultural groups, and artifacts
Effect of a glyphosate-containing herbicide on Escherichia coli and Salmonella Ser. Typhimurium in an in vitro rumen simulation system
Glyphosate (N-(phosphonomethyl)glycine) is the most-used herbicide worldwide. Many studies in the past have shown that residues of the herbicide can be found in many cultivated plants, including those used as livestock feed. Sensitivity to glyphosate varies with bacteria, particularly those residing in the intestine, where microbiota is exposed to glyphosate residues. Therefore, less susceptible pathogenic isolates could have a distinct advantage compared to more sensitive commensal isolates, probably leading to dysbiosis.
To determine whether the ruminal growth and survival of pathogenic Escherichia coli or Salmonella serovar Typhimurium are higher when glyphosate residues are present in the feed, an in vitro fermentation trial with a âRumen Simulation Systemâ (RUSITEC) and a glyphosate-containing commercial formulation was performed.
Colony forming units of E. coli and Salmonella ser. Typhimurium decreased steadily in all fermenters, regardless of the herbicide application. Minimum inhibitory concentrations of the studied Salmonella and E. coli strains did not change, and antibiotic susceptibility varied only slightly but independent of the glyphosate application.
Overall, application of the glyphosate-containing formulation in a worst-case concentration of 10âmg/L neither increased the abundance for the tested E. coli and Salmonella strain in the in vitro fermentation system, nor promoted resistance to glyphosate or antibiotics
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