Advances in Archaeological Practice 7 (2): 178-184, 2019
Formal models of past human societies informed by archaeological research have a high potential f... more Formal models of past human societies informed by archaeological research have a high potential for shaping some of the most topical current debates. Agent-based models, which emphasize how actions by individuals combine to produce global patterns, provide a convenient framework for developing quantitative models of historical social processes. However, being derived from computer science, the method remains largely specialized in archaeology. In this paper and the associated tutorial, we provide a jargon-free introduction to the technique, its potential and limits as well as its diverse applications in archaeology and beyond. We discuss the epistemological rationale of using computational modeling and simulation, classify types of models, and give an overview of the main concepts behind agent-based modeling. Modelos cuantitativos robustos de sociedades humanas en el pasado tienen el potencial de informar los temas de debate actual, parti-cularmente modelos informados por estudios de arqueología. Modelos basados en sistemas multiagente proveen un marco práctico para explorar modelos cuantitativos de sociedades en el pasado. Aun así, al ser un método de informática no es aún bien establecido entre la mayoría de arqueólogos. En este artículo y el tutorial que lo acompaña, proveemos una introducción a estos métodos, libres de jerga técnica, su potencial y sus límites, y también las diversas aplicaciones en arqueología. Además, discutimos la epistemología de utilizar modelos computacionales y de simulación, clasificamos los tipos de modelos, y proveemos un resumen de los conceptos principales de los modelos multiagente. Palabras clave: Q2
Agent-based modeling (ABM) is a powerful tool for understanding the dynamics of past social syste... more Agent-based modeling (ABM) is a powerful tool for understanding the dynamics of past social systems. Drawing on a survey of self-identified agent-based modelers in archaeology, we describe this community of practice in terms of gender, education, employment, and research practices, highlighting similarities with, and distinctions from, the community of archaeologists at large. From the findings of the survey, we argue that more engagement with questions of practice within the modeling community, and more intra-disciplinary development of ABM teaching resources, may help to mainstream model thinking and reduce barriers to ABM use in archaeology.
Evidence for changes in human mobility is fundamental to interpretations of transitions in human ... more Evidence for changes in human mobility is fundamental to interpretations of transitions in human socioeconomic organization. Showing changes in mobility requires both archaeological proxies that are sensitive to movement and a clear understanding of how different mobility configurations influence their patterning. This study uses computer simulation to explore how different combinations of reduction, selection, transport, and discard of stone artifacts generate patterning in the “cortex ratio,” a geometric proxy used to demonstrate movement at the assemblage level. A case study from western New South Wales, Australia, shows how cortex ratios are used to make inferences about movement. Results of the exploratory simulation show that redundancy in movement between discards reduces variability in cortex ratios, while mean assemblage values can be attributed to the relative proportions of artifacts carried into and out of the assemblages. These results suggest that raw material availability is a potentially crucial factor in determining what kinds of mobility are visible in assemblages, whereby different access to raw material can shift the balance of import and export of stone in an otherwise undirected movement configuration. These findings are used to contextualize distributions of cortex ratios from the raw material–rich study area, prompting suggestions for further fieldwork.
The generative nature of the archaeological record stands in contrast with reconstructive goals o... more The generative nature of the archaeological record stands in contrast with reconstructive goals of the discipline. This is particularly evident in discussions of surface archaeology, which is often considered deficient for reconstructing human behavior in the past when compared with subsurface deposits. We look at a case study from Rutherfords Creek in arid southeastern Australia, where lithics and combustion features appear in differing densities across the surface. These have been interpreted variably in terms of settlement patterns; however, the relationships between accumulation, visibility, and preservation are complex. This study addresses these relationships in terms of formation dynamics, drawing out patterns from surface assemblages that bear on the mobility and resilience of the ancestral Aboriginal populations that occupied Rutherfords Creek during the late Holocene. A different view of the record emerges, one that foregrounds the notions of reversibility in the patterning to identify the kinds of questions the record might be most fruitfully brought to bear on, with implications for both surface and subsurface archaeology.
Archaeologists make inferences about past human behaviour based on patterned material residues in... more Archaeologists make inferences about past human behaviour based on patterned material residues in various depositional contexts, including existing landsurfaces. These deposits are generated by processes that may obscure patterns at some observational scales while highlighting others, and interpretive differences can arise from a lack of explicit models of deposit formation. Here, an exploratory agent-based model based on the concept of the palimpsest is used to examine the effects of episodic sediment transport on the visibility and preservation of surface archaeological deposits in a fluvial context. Outcomes from the model indicate that the compound influences of preservation and visibility are capable of transforming a static radiocarbon record into one of increasing intensity towards the present, while simultaneously displaying periodic chronological gaps – features that have been used in our Australian study area to argue for demographic change driven by social or environmental factors. To differentiate between interpretations, expectations derived from the model are assessed against a second proxy from the same study area: Optically Stimulated Luminescence dates from hearth stones in surface contexts. Results indicate that patterns in the chronometric proxies from the study area are more consistent with episodic geomorphic change than explanations invoking changes in the local organization of human activity.
Archaeologists make inferences about past human behaviour based on patterned material residues in... more Archaeologists make inferences about past human behaviour based on patterned material residues in various sedimentary contexts, including existing landsurfaces. These deposits are generated by processes that may obscure some observational scales while highlighting others, and interpretive differences may arise from a lack of explicit models of deposit formation. Here, an exploratory agent-based model based on the concept of the palimpsest is used to examine the effects of episodic sediment transport on the visibility and preservation of surface archaeological deposits in a fluvial context. Outcomes from the model indicate that the compound influences of preservation and visibility are capable of transforming a static radiocarbon record into one of increasing intensity toward the present, while simultaneously displaying periodic chronological gaps - features that have been used in our Australia study area to argue for demographic change driven by social or environmental factors. To differentiate between interpretations, expectations derived from the model are assessed against a second proxy from the same study area, namely optically-stimulated luminescence dates from hearth stones in surface contexts. Results indicate that patterns in the chronometric proxies from the study area are more consistent with episodic geomorphic change than explanations invoking changes in the local organisation of human activity.
Humans have been traversing the world’s oceans for at least 50,000 years. For archaeologists inte... more Humans have been traversing the world’s oceans for at least 50,000 years. For archaeologists interested in prehistoric seafaring, computer simulation has proven a useful method for investigating the challenges and strategies used in the past. However, a number of barriers have inhibited wider adoption of the simulation approach. We present a prototype for a flexible voyaging simulation to model prehistoric seafaring. Combining freeware technologies in GIS, statistics, and agent-based modelling with open source datasets, our simulation is capable of testing hypotheses ranging from drift to directed voyaging across the globe, at comparable or higher resolution than previous studies. A case study from the Pacifc is offered which demonstrates some of the capabilities of the system. In time, we hope to introduce this as a tool for researchers worldwide to explore questions of prehistoric oceanic voyaging.
The archaeological landscapes of arid environments often feature surface scatters of stone artefa... more The archaeological landscapes of arid environments often feature surface scatters of stone artefacts, which are used to infer past human activity and organization. For hunter-gatherer groups this typically involves some interpretation of mobility; however, the scales of activity inferred from these assemblages usually extend beyond the boundaries of study areas. Understanding what these assemblages mean in terms of human mobility requires assessment of how samples fit within a wider landscape distribution. This study uses computer simulation to evaluate interpretations of mobility and place use from the ratio of cortical to non-cortical stone in surface assemblages from arid western New South Wales, Australia. First, the cortex ratio concept is investigated using an agent-based model coupled with an experimental dataset. These initial model outcomes are found to be consistent with expectations from the distribution of cortex, and the influence of core reduction intensity and selection intensity on assemblage variation is demonstrated. Second, a measure called the cumulative cortex ratio is proposed for evaluating the dispersal of cortex over a continuous surface. Finally, the differential distribution of cortex within the Rutherford’s Creek study area is assessed by simulating different scenarios of place use and computing the cumulative cortex ratio on simulated data.
Peoples in Remote Oceania tend, on average, to be moderately tall, with relatively broad shoulder... more Peoples in Remote Oceania tend, on average, to be moderately tall, with relatively broad shoulders and hips as compared to people from probable source populations identified in recent population genetic studies and analyses of craniometric variation from skeletal samples. While several explanations have been offered for this, a common theme is the role played by repeated genetic bottlenecking, an outcome of serial migration. We have constructed a computational, individual-based demographic model to explore the effects of serial migration on the probability of change in body dimensions in a human population. Our model is flexible, and the impacts of several initial anthropometric distributions are considered. Agents within the model age, and are subject to a range of age- and sex-specific mortality risks and fertility estimates derived from various living populations. Individuals’ adult body sizes are simulated using standard-normal z-score distributions of height, biiliac breadth, and biacromial breadth. These are correlated in biologically meaningful ways within individuals and are transmitted from parents to offspring in a biologically plausible manner. Correlations of characteristics between parents and offspring and among offspring also vary within biologically plausible ranges. Finally, regional archaeological studies are used to provide temporal constraints for colonisation events. Numerous scenarios are evaluated, suggesting that repeated bottlenecking events alone are not sufficient to explain this phenomenon. Alternative hypotheses, and means of assessing them, are discussed.
This paper discusses complex systems and model-based science in the context of archaeological inq... more This paper discusses complex systems and model-based science in the context of archaeological inquiry. There has been a growing interest in applying the concepts of complex systems theory, such as self-organisation and emergence, to archaeological problems. Modelling, and in particular simulation, has long been established as the preferred approach to complex systems, and the proliferation of cheap and powerful computing has extended these approaches to more specific research domains. However, model-based science is only a recently acknowledged paradigm, and differs in important ways from more established concepts of science. These differences are discussed alongside core concepts of model-building and complex systems. Examples using agent-based models are drawn from bioarchaeological research on the prehistoric settlement of Remote Oceania, demonstrating both promise and pitfalls for model-based approaches.
Geoarchaeological research at Rutherfords Creek in western New South Wales indicates that lithic ... more Geoarchaeological research at Rutherfords Creek in western New South Wales indicates that lithic assemblages are, on average, depleted in cortex, a pattern attributed to the removal of unmodified stone flakes from the creek catchment. In order to assess how different patterns of mobility and curation influence the composition of lithic assemblages within the catchment itself, a series of exploratory computational models are constructed to experiment within a surrogate system. Results suggest that while ratios are sensitive to differences in place use, limited redundancy in place use is indicated at Rutherfords Creek.
Recent geoarchaeological research at Rutherfords Creek indicates that lithic assemblages are, on ... more Recent geoarchaeological research at Rutherfords Creek indicates that lithic assemblages are, on average, depleted in cortex, a pattern attributed to the removal of unmodified stone flakes away from the creek catchment. In order to assess how different patterns of mobility and curation influence the composition of lithic assemblages within the catchment itself, a series of computational models are constructed to experiment within a surrogate system. Results suggest that while assemblages are sensitive to differences in place use, limited redundancy in place use is indicated at Rutherfords Creek.
Research into prehistoric seafaring has a relatively long history of computer simulation studies.... more Research into prehistoric seafaring has a relatively long history of computer simulation studies. Previous simulations combined with experimental voyaging studies describe how the Pacific was explored and settled in prehistory. This has influenced studies of seafaring in other regions of the world. Recent efforts have taken advantage of the greater availability of large-scale climate data sets, leading to questions regarding the reliability of older simulations as well as an opportunity to test more realistic scenarios.
Advances in Archaeological Practice 7 (2): 178-184, 2019
Formal models of past human societies informed by archaeological research have a high potential f... more Formal models of past human societies informed by archaeological research have a high potential for shaping some of the most topical current debates. Agent-based models, which emphasize how actions by individuals combine to produce global patterns, provide a convenient framework for developing quantitative models of historical social processes. However, being derived from computer science, the method remains largely specialized in archaeology. In this paper and the associated tutorial, we provide a jargon-free introduction to the technique, its potential and limits as well as its diverse applications in archaeology and beyond. We discuss the epistemological rationale of using computational modeling and simulation, classify types of models, and give an overview of the main concepts behind agent-based modeling. Modelos cuantitativos robustos de sociedades humanas en el pasado tienen el potencial de informar los temas de debate actual, parti-cularmente modelos informados por estudios de arqueología. Modelos basados en sistemas multiagente proveen un marco práctico para explorar modelos cuantitativos de sociedades en el pasado. Aun así, al ser un método de informática no es aún bien establecido entre la mayoría de arqueólogos. En este artículo y el tutorial que lo acompaña, proveemos una introducción a estos métodos, libres de jerga técnica, su potencial y sus límites, y también las diversas aplicaciones en arqueología. Además, discutimos la epistemología de utilizar modelos computacionales y de simulación, clasificamos los tipos de modelos, y proveemos un resumen de los conceptos principales de los modelos multiagente. Palabras clave: Q2
Agent-based modeling (ABM) is a powerful tool for understanding the dynamics of past social syste... more Agent-based modeling (ABM) is a powerful tool for understanding the dynamics of past social systems. Drawing on a survey of self-identified agent-based modelers in archaeology, we describe this community of practice in terms of gender, education, employment, and research practices, highlighting similarities with, and distinctions from, the community of archaeologists at large. From the findings of the survey, we argue that more engagement with questions of practice within the modeling community, and more intra-disciplinary development of ABM teaching resources, may help to mainstream model thinking and reduce barriers to ABM use in archaeology.
Evidence for changes in human mobility is fundamental to interpretations of transitions in human ... more Evidence for changes in human mobility is fundamental to interpretations of transitions in human socioeconomic organization. Showing changes in mobility requires both archaeological proxies that are sensitive to movement and a clear understanding of how different mobility configurations influence their patterning. This study uses computer simulation to explore how different combinations of reduction, selection, transport, and discard of stone artifacts generate patterning in the “cortex ratio,” a geometric proxy used to demonstrate movement at the assemblage level. A case study from western New South Wales, Australia, shows how cortex ratios are used to make inferences about movement. Results of the exploratory simulation show that redundancy in movement between discards reduces variability in cortex ratios, while mean assemblage values can be attributed to the relative proportions of artifacts carried into and out of the assemblages. These results suggest that raw material availability is a potentially crucial factor in determining what kinds of mobility are visible in assemblages, whereby different access to raw material can shift the balance of import and export of stone in an otherwise undirected movement configuration. These findings are used to contextualize distributions of cortex ratios from the raw material–rich study area, prompting suggestions for further fieldwork.
The generative nature of the archaeological record stands in contrast with reconstructive goals o... more The generative nature of the archaeological record stands in contrast with reconstructive goals of the discipline. This is particularly evident in discussions of surface archaeology, which is often considered deficient for reconstructing human behavior in the past when compared with subsurface deposits. We look at a case study from Rutherfords Creek in arid southeastern Australia, where lithics and combustion features appear in differing densities across the surface. These have been interpreted variably in terms of settlement patterns; however, the relationships between accumulation, visibility, and preservation are complex. This study addresses these relationships in terms of formation dynamics, drawing out patterns from surface assemblages that bear on the mobility and resilience of the ancestral Aboriginal populations that occupied Rutherfords Creek during the late Holocene. A different view of the record emerges, one that foregrounds the notions of reversibility in the patterning to identify the kinds of questions the record might be most fruitfully brought to bear on, with implications for both surface and subsurface archaeology.
Archaeologists make inferences about past human behaviour based on patterned material residues in... more Archaeologists make inferences about past human behaviour based on patterned material residues in various depositional contexts, including existing landsurfaces. These deposits are generated by processes that may obscure patterns at some observational scales while highlighting others, and interpretive differences can arise from a lack of explicit models of deposit formation. Here, an exploratory agent-based model based on the concept of the palimpsest is used to examine the effects of episodic sediment transport on the visibility and preservation of surface archaeological deposits in a fluvial context. Outcomes from the model indicate that the compound influences of preservation and visibility are capable of transforming a static radiocarbon record into one of increasing intensity towards the present, while simultaneously displaying periodic chronological gaps – features that have been used in our Australian study area to argue for demographic change driven by social or environmental factors. To differentiate between interpretations, expectations derived from the model are assessed against a second proxy from the same study area: Optically Stimulated Luminescence dates from hearth stones in surface contexts. Results indicate that patterns in the chronometric proxies from the study area are more consistent with episodic geomorphic change than explanations invoking changes in the local organization of human activity.
Archaeologists make inferences about past human behaviour based on patterned material residues in... more Archaeologists make inferences about past human behaviour based on patterned material residues in various sedimentary contexts, including existing landsurfaces. These deposits are generated by processes that may obscure some observational scales while highlighting others, and interpretive differences may arise from a lack of explicit models of deposit formation. Here, an exploratory agent-based model based on the concept of the palimpsest is used to examine the effects of episodic sediment transport on the visibility and preservation of surface archaeological deposits in a fluvial context. Outcomes from the model indicate that the compound influences of preservation and visibility are capable of transforming a static radiocarbon record into one of increasing intensity toward the present, while simultaneously displaying periodic chronological gaps - features that have been used in our Australia study area to argue for demographic change driven by social or environmental factors. To differentiate between interpretations, expectations derived from the model are assessed against a second proxy from the same study area, namely optically-stimulated luminescence dates from hearth stones in surface contexts. Results indicate that patterns in the chronometric proxies from the study area are more consistent with episodic geomorphic change than explanations invoking changes in the local organisation of human activity.
Humans have been traversing the world’s oceans for at least 50,000 years. For archaeologists inte... more Humans have been traversing the world’s oceans for at least 50,000 years. For archaeologists interested in prehistoric seafaring, computer simulation has proven a useful method for investigating the challenges and strategies used in the past. However, a number of barriers have inhibited wider adoption of the simulation approach. We present a prototype for a flexible voyaging simulation to model prehistoric seafaring. Combining freeware technologies in GIS, statistics, and agent-based modelling with open source datasets, our simulation is capable of testing hypotheses ranging from drift to directed voyaging across the globe, at comparable or higher resolution than previous studies. A case study from the Pacifc is offered which demonstrates some of the capabilities of the system. In time, we hope to introduce this as a tool for researchers worldwide to explore questions of prehistoric oceanic voyaging.
The archaeological landscapes of arid environments often feature surface scatters of stone artefa... more The archaeological landscapes of arid environments often feature surface scatters of stone artefacts, which are used to infer past human activity and organization. For hunter-gatherer groups this typically involves some interpretation of mobility; however, the scales of activity inferred from these assemblages usually extend beyond the boundaries of study areas. Understanding what these assemblages mean in terms of human mobility requires assessment of how samples fit within a wider landscape distribution. This study uses computer simulation to evaluate interpretations of mobility and place use from the ratio of cortical to non-cortical stone in surface assemblages from arid western New South Wales, Australia. First, the cortex ratio concept is investigated using an agent-based model coupled with an experimental dataset. These initial model outcomes are found to be consistent with expectations from the distribution of cortex, and the influence of core reduction intensity and selection intensity on assemblage variation is demonstrated. Second, a measure called the cumulative cortex ratio is proposed for evaluating the dispersal of cortex over a continuous surface. Finally, the differential distribution of cortex within the Rutherford’s Creek study area is assessed by simulating different scenarios of place use and computing the cumulative cortex ratio on simulated data.
Peoples in Remote Oceania tend, on average, to be moderately tall, with relatively broad shoulder... more Peoples in Remote Oceania tend, on average, to be moderately tall, with relatively broad shoulders and hips as compared to people from probable source populations identified in recent population genetic studies and analyses of craniometric variation from skeletal samples. While several explanations have been offered for this, a common theme is the role played by repeated genetic bottlenecking, an outcome of serial migration. We have constructed a computational, individual-based demographic model to explore the effects of serial migration on the probability of change in body dimensions in a human population. Our model is flexible, and the impacts of several initial anthropometric distributions are considered. Agents within the model age, and are subject to a range of age- and sex-specific mortality risks and fertility estimates derived from various living populations. Individuals’ adult body sizes are simulated using standard-normal z-score distributions of height, biiliac breadth, and biacromial breadth. These are correlated in biologically meaningful ways within individuals and are transmitted from parents to offspring in a biologically plausible manner. Correlations of characteristics between parents and offspring and among offspring also vary within biologically plausible ranges. Finally, regional archaeological studies are used to provide temporal constraints for colonisation events. Numerous scenarios are evaluated, suggesting that repeated bottlenecking events alone are not sufficient to explain this phenomenon. Alternative hypotheses, and means of assessing them, are discussed.
This paper discusses complex systems and model-based science in the context of archaeological inq... more This paper discusses complex systems and model-based science in the context of archaeological inquiry. There has been a growing interest in applying the concepts of complex systems theory, such as self-organisation and emergence, to archaeological problems. Modelling, and in particular simulation, has long been established as the preferred approach to complex systems, and the proliferation of cheap and powerful computing has extended these approaches to more specific research domains. However, model-based science is only a recently acknowledged paradigm, and differs in important ways from more established concepts of science. These differences are discussed alongside core concepts of model-building and complex systems. Examples using agent-based models are drawn from bioarchaeological research on the prehistoric settlement of Remote Oceania, demonstrating both promise and pitfalls for model-based approaches.
Geoarchaeological research at Rutherfords Creek in western New South Wales indicates that lithic ... more Geoarchaeological research at Rutherfords Creek in western New South Wales indicates that lithic assemblages are, on average, depleted in cortex, a pattern attributed to the removal of unmodified stone flakes from the creek catchment. In order to assess how different patterns of mobility and curation influence the composition of lithic assemblages within the catchment itself, a series of exploratory computational models are constructed to experiment within a surrogate system. Results suggest that while ratios are sensitive to differences in place use, limited redundancy in place use is indicated at Rutherfords Creek.
Recent geoarchaeological research at Rutherfords Creek indicates that lithic assemblages are, on ... more Recent geoarchaeological research at Rutherfords Creek indicates that lithic assemblages are, on average, depleted in cortex, a pattern attributed to the removal of unmodified stone flakes away from the creek catchment. In order to assess how different patterns of mobility and curation influence the composition of lithic assemblages within the catchment itself, a series of computational models are constructed to experiment within a surrogate system. Results suggest that while assemblages are sensitive to differences in place use, limited redundancy in place use is indicated at Rutherfords Creek.
Research into prehistoric seafaring has a relatively long history of computer simulation studies.... more Research into prehistoric seafaring has a relatively long history of computer simulation studies. Previous simulations combined with experimental voyaging studies describe how the Pacific was explored and settled in prehistory. This has influenced studies of seafaring in other regions of the world. Recent efforts have taken advantage of the greater availability of large-scale climate data sets, leading to questions regarding the reliability of older simulations as well as an opportunity to test more realistic scenarios.
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complex. This study addresses these relationships in terms of formation dynamics, drawing out patterns from surface assemblages that bear on the mobility and resilience of the ancestral Aboriginal populations
that occupied Rutherfords Creek during the late Holocene. A different view of the record emerges, one that foregrounds the notions of reversibility in the patterning to identify the kinds of questions the record might be most fruitfully brought to bear on, with implications for both surface and subsurface archaeology.
complex. This study addresses these relationships in terms of formation dynamics, drawing out patterns from surface assemblages that bear on the mobility and resilience of the ancestral Aboriginal populations
that occupied Rutherfords Creek during the late Holocene. A different view of the record emerges, one that foregrounds the notions of reversibility in the patterning to identify the kinds of questions the record might be most fruitfully brought to bear on, with implications for both surface and subsurface archaeology.