A geometric morphometrics-based assessment of blade shape differences among Paleoindian projectile point types from western North America

Blade shape features in the type definitions of Clovis, Folsom, and Plainview projectile points. However, the accuracy of these assessments has never been evaluated. Here we report a study in which geometric morphometrics and multivariate statistics were used to compare the shapes of the blades of Clovis, Folsom and Plainview points from the Southern Plains of North America. In the course of the analyses, we controlled for the impact of three potential confounding factors: allometry, differences in raw material quality, and resharpening. The analyses show that blade shape distinguishes Clovis points from both Folsom points and Plainview points, but does not distinguish Folsom points from Plainview points. The analyses also show that the similarities and differences in blade shape among the types are independent of allometry, raw material quality, and resharpening. These findings suggest that the type definitions for Clovis, Folsom and Plainview need to be altered. They also have implications for typing specimens that lack other defining characters (e.g. channel flakes, flutes). Lastly, the absence of resharpening effects raises questions about the validity of the reduction thesis.     

Points and prey: a quantitative test of the hypothesis that prey size influences early Paleoindian projectile point form

Understanding the causes of variation within and between projectile point types is an important task for Paleoindian archaeologists since they rely heavily on points to investigate such things as settlement dynamics and hunting practices. One long-held explanation for the variation in early Paleoindian point form is that prey size influenced the size and shape of projectile points. The study reported here evaluated this hypothesis with standard and geometric morphometric data recorded on Clovis and Folsom points from the Southern Plains and Southwest that are associated with mammoth or bison remains. Points used to hunt mammoth were found to be larger and of a different shape than points used to hunt bison, which supports the hypothesis. However, when both point type and prey size were taken into account, the results ran counter to predictions. Potential explanations for this discrepancy are discussed.     

Anticipated mobility and its archaeological signature: A case study of Folsom retooling strategies

This essay highlights the value of anticipated mobility for untangling variability in prehistoric stone tool manufacture. To do so, it explores the organization of weaponry production at a series of Folsom campsites via the highly visible archaeological signature of Folsom fluting. A model of weaponry replacement based on deep planning and anticipation of needs is proposed, according to which Folsom hunters commonly replace their projectile points as they wear down, break or are lost, but on fewer occasions engage in the mass production of fluted points. This technological organization is consistent with a highly mobile way of life in which advanced planning buffers the risk associated with limited or stochastic access to good quality lithic raw materials. The model is then put to the test at the Lindenmeier site in northern Colorado. The spatial patterning of fluting activities in two discrete areas of the site demonstrates contrasting strategies of point manufacture: conservation versus gearing up (creation of a surplus). It is argued that these patterns represent distinct facets of a single technological organization.     

Static penetration assessment of stone weapon tip geometry metrics and comparison of static and dynamic penetration depths

Many factors governed the penetration efficacy of prehistoric projectile weaponry. Archaeologists broadly focus their efforts on understanding the effect of stone weapon tips because these specimens are often the only part of the weapon system that survives in the archaeological record. The tip cross-sectional area (TCSA) and perimeter (TCSP) of stone weapon tips have been shown to correlate with target penetration depth. Here, using results from both static and dynamic penetration testing, we compare TCSA and TCSP against other tip geometry metrics: lateral surface area (LSA) and volume (V). Our analyses broadly show that using a single-point geometry metric evaluated at multiple locations along the length of the point, or using multiple geometry metrics evaluated at a single location, better predicts required energy than using a single-point geometry metric evaluated at a single location. Our results also show that in the case where a single geometry metric evaluated at multiple locations is used LSA provided the most robust prediction models. Finally, our results show that for the case where all geometry metrics evaluated at a single location are used the location that provides the most robust prediction model is dependent on how far the point penetrated the target.     

Assessing Collector Bias: A Geometric Morphometric Analysis of a Collection of Isolated Clovis Points from the Midcontinent

Clovis points are found across the contiguous United States as isolated surface finds and as elements of assemblages in surface and subsurface deposits. Despite being scattered over the continent, Clovis points exhibit a remarkable degree of standardization, yet there is still a demonstrable level of variation in their shapes across regions. Including isolated points in regional comparative analyses would significantly increase sample sizes and spatial coverage of these analyses; however, the effects of collector bias—the tendency to collect the most typical and aesthetically pleasing points—are unknown. Here, we examine the shape of a sample of isolated Clovis points from the midcontinent using geometric morphometric techniques. We show that resharpening had little effect on the shape of points and that our sample of isolated points are similar in shape to points from assemblages in the midcontinent. Our findings suggest that isolated points have research potential when collector bias is limited.     

Spatiotemporal dynamics of the Clovis–Folsom transition

Despite the importance of the Clovis–Folsom transition for understanding the history of western North America, its spatiotemporal dynamics remains unclear. Here we report a three-part study in which we investigated the transition using radiocarbon dates from Clovis and Folsom sites. In the first part of the study, we used dates from Folsom site-phases to determine when and where Folsom originated. In the second part of the study, we employed Clovis and Folsom dates in analyses designed to determine whether Folsom spread via demic diffusion or cultural diffusion. In the third part of the study we investigated the velocity of the Clovis–Folsom transition. The analyses suggest that Folsom first appeared around 12,800 calBP in the northern High Plains and spread north and south from there. They also suggest that the spread of Folsom was, at least in part, the result of population expansion. In addition, the analyses indicate that the spread of Folsom was relatively fast for a prehistoric diffusion but well below the maximum velocity that has been estimated for such events. These findings, in turn, have implications for the hypotheses that have been put forward to explain the Clovis–Folsom transition. They refute the idea that the Clovis–Folsom transition resulted from an extraterrestrial impact over northern North America at 12,900 ± 100 calBP but are consistent with the alternative proposal that the transition was a response to climate-driven environmental change.     

The northern fluted point complex: technological and morphological evidence of adaptation and risk in the late Pleistocene-early Holocene Arctic

Analyses of fluted point technology and Paleoindian technological risk have contributed to our understanding of human adaptation across North America in the late Pleistocene and early Holocene. However, poor chronological control has dissuaded similar studies of fluted points found in Alaska and northern Yukon and our understanding of their adaptive role in early arctic adaptations remains unclear. Two new archeological sites have provided reliable radiocarbon data and for the first time, a comprehensive analysis of northern fluted points is possible. Here, technological and morphological analyses of northern fluted points are presented, including variables statistically evaluated and compared to a collection of fluted Folsom artifacts serving as a reference. Variation in tool shape was measured using geometric morphometrics, and a new approach to landmark placement designed to characterize basal morphology and allow the analysis to include tool fragments is presented. Results confirm that northern fluted points represent a cohesive technological strategy and are used to formulate hypotheses suggesting its service as a risk-management system promoting ease-of-replacement-after-failure to offset transport costs and reduce risk during long-distance travel.     

Clovis,Folsom, and Midland components at the Debra L. Friedkin site,Texas: context,chronology, and assemblages

The archaeological transition from Clovis to Folsom and Midland in the North American Great Plains coincides with the end of the Pleistocene and onset of the Younger Dryas. Comparisons exploring the adaptive changes that took place during this period frequently employ regional-scale approaches. The focus on regional-scale analyses largely results from the dearth of sites repeatedly visited by multiple early Paleoindian groups. However, regional-scale comparisons have the potential to overlook smaller-scale differences. The Debra L. Friedkin site, Texas offers an opportunity to study Midland, Folsom, and Clovis technology and site-use at a single site. This paper presents the context and chronology of the Midland, Folsom, and Clovis assemblages and a site-scale analysis of lithics from the Friedkin site. It is argued that point production and late-stage reduction were primary activities, and the use of bifacial cores for flake tools was important throughout these occupation periods. Site use at Friedkin differs from early Paleoindian occupation at the nearby Gault site and expands our understanding of settlement and technological organization in the region.     

Continent-wide or region-specific? A geometric morphometrics-based assessment of variation in Clovis point shape

Researchers have debated the existence of regional variation in Clovis points for over 60 years. Here, we report an attempt to resolve this argument using a large sample of Clovis points from dated assemblages and a suite of shape analysis methods known as geometric morphometrics. The study tested the two main hypotheses that have been put forward in the debate: the continent-wide adaptation hypothesis, which holds that Clovis points do not vary regionally, and the regional environmental adaptation hypothesis, which holds that there is regional variation as a consequence of Clovis groups adjusting their food-getting toolkits to local conditions. We used discriminant function analysis and a multivariate extension of the t test to assess whether differences in shape exist at two scales. The first set of analyses compared points from the most obvious environmental regions in North America, the East and the West. The second set of analyses investigated differences among points from subregions within the East and West. The analyses revealed significant differences between points from the East and the West and among points from some subregions. Follow-up analyses demonstrated that these differences are not the result of the most common confounding factors, raw material quality and resharpening. As such, the analyses support the regional environmental adaptation hypothesis rather than the continent-wide adaptation hypothesis. We conclude from this that Clovis people modified their points to suit the characteristics of local prey and/or the habitats in which they hunted.     

Ontogenetic scaling and lithic systematics: method and application

Stone tools tend to be classified according to a mix of functional, morphological, and technological attributes. This practice results in confusions when large-scale assemblage comparisons are made with the aim of investigating phylogenetic relationships, as functional and cultural information is aggregated. It is argued here that functional criteria must be assessed separately, and that resharpening, as a uniform, repeated, conscious behavioral process of tool maintenance that indexes use and function, can provide a solution to this problem. The subject of this article is a quantitative method for extracting and comparing resharpening trajectories. The method is an adaptation of ontogenetic scaling methods from biology, and is based on obtaining a mathematical representation of shape and size, and finding a relationship between the two. Elliptical Fourier analysis is applied to stone tool contours in order to extract shape information, and then a series of regressions of shape on size provide trajectory vectors. The angles between these are then calculated and subjected to a variety of multivariate statistical tests. A case study involving several European Middle Paleolithic bifacial and unifacial tool assemblages is presented. The results show that resharpening and maintenance can be independent of morphology and technology, suggesting that there are strong grounds for focusing on functional systematics separately.     

Modeling post-depositional mixing of archaeological deposits

We develop a series of simple mathematical models that describe vertical mixing of archaeological deposits. The models are based on assigning probabilities that single artifact specimens are moved between discrete stratigraphic layers. A recursion relation is then introduced to describe the time evolution of mixing. Simulations are used to show that there may be important regularities that characterize the mixing of archaeological deposits including stages of dissipation, accumulation and equilibration. We discuss the impact of post-depositional mixing on the apparent occupation intensities at modeled stratified archaeological sites. The models may also help clarify some of the problems inherent in making general inferences about the nature culture change based on mixed archaeological deposits. We demonstrate the modeling approach by developing a post-depositional mixing model for the Barger Gulch Folsom site.     

Modeling Interaction in a System of Markets

This paper develops a nested family of market interaction models for the general case of spatial or aspatial goods. Market structure effects are identified in the form of intraregional and extraregional competition. The competing destinations and competing central place models are shown to be special cases of the general modeling framework. An empirical example, using survey data collected from Chicago-area Management and Public Relations (SIC 874) firms, illustrates how the family of models may be used to identify market structure.     

Bison butchery at Cooper,a Folsom site on the Southern Plains

Cooper, a Folsom arroyo-trap bison kill site in northwest Oklahoma is composed of three large-scale kill episodes. The bison bones have been examined for butchering evidence and exploring the butchering pattern. Damage categories to cortical bone are indentation, cut mark, helical fracture, and impact blow. The 99 elements damaged are from 36 carcasses across all three kills, and damage morphology indicates both lithic and bone expediency tools were used in the butchering. Animals are being butchered in an upright position on their stomachs, with transverse and abdominal muscles the focal point. Experimental butchering of a bison replicates the reconstructed sequence and underscores a gourmet butchering style for the Cooper kills.     

Getting to the point: Evolutionary change in prehistoric weaponry

The evolution of prehistoric weaponry remains an open question in North American archaeology. The traditional model argues for an early use of the throwing spear followed by the spearthrower and bow and arrow. A major difficulty in testing this model is, identifying the functional variables that characterize different weaponry. The evolution of prehistoric weaponry is reexamined here from an evolutionary perspective where projectile points are considered part of the complete weapon system and variation within that system is identified. The engineering of four weapon systems, the thrusting spear, throwing spear, spearthrower, and bow, are examined to identify those point variables that enhance the success of the system. These variables are then measured on a 9000-year sequence of projectile points from northwestern Wyoming to examine time/space patterns. The patterns reveal that the spearthrower was in use prior to 7500 years ago.     

Accuracy of Count Data Estimated by the Point‐in‐Polygon Method

This paper analyzes the accuracy of count data estimated by the point‐in‐polygon method. A point‐in‐polygon interpolation model is proposed, based on a stochastic distribution of points and the target zone, in order to represent a variety of situations. The accuracy of estimates is numerically investigated in relation to the size of the target zone and the distribution of points, and the optimal location of representative points is discussed. The major findings of this paper are as follows: (1) though the relative accuracy of estimates generally increases monotonously with the size of the target zone, the monotoneity is often disturbed by the periodicity in the spatial configuration of source zones and the point distribution; (2) the point‐in‐polygon and the areal weighting interpolation methods have the same accuracy of estimates when points are concentrated in less than 12–15 percent area around the representative point in source zones; (3) the point‐in‐polygon method is not so robust against the locational gap between points and the representative point; (4) the optimal location of representative points is given by the spatial median of points.     

Investigating the potential of micro-focus computed tomography in the study of ancient bone tool function: results from actualistic experiments

Many experiments have sought to recreate the types of damage that would be expected in ancient stone and bone weapon tips. This damage is usually presented as visible fractures or microscopic surface modification. Fatigue tests conducted on bovine bones, however, show the development of internal micro-cracks that result from stress, prior to actual breakage. In this paper I present the results of an experimental investigation of bone points subjected to a variety of activities. I assess the presence of microdamage using micro-focus computed tomography. The results show that two patterns of micro-cracks develop in bone and are best viewed in longitudinal section. Micro-cracks are a cumulative feature dependent on the amount of load applied and the duration of activity. When subjected to high enough loading rates, micro-cracks will merge together to eventually form a fracture. Although further tests are needed to confirm the exact point at which these fatigue fractures begin to form, micro-focus computed tomography has the potential to reveal whether an individual bone point underwent multiple or prolonged impacts and thus to elucidate the probable function/s of ancient pointed bone tools where no visible damage is apparent. Micro-focus computed tomography is a non-destructive and non-invasive procedure and therefore safe to use on archaeological artefacts.     

The craniology and relationships of four species of Bos 3. Basic craniology: Bos taurus L. Sagittal profiles and other non-measurable characters

This paper is the third in a series on the craniology of four species of Bos and it is the last of the three papers in which the skulls of British domestic cattle are used in an attempt to establish a basic craniology for the genus. Part 1 (Grigson, 1974) dealt with nomenclature, material, history, age assessment and absolute size. Part 2 (Grigson, 1975) dealt with cranial proportions and angles. This paper deals first with sagittal profiles and then with other non-measurable characters.Sagittal profiles may be rounded or pointed with some intermediate forms. The rounded shape (an infantile character) persists throughout life in some breeds and is unaffected by age, sex or size. The pointed form develops with age in some breeds and is probably more marked in older and larger animals. Seventeen other minor characters are examined for the effects of age, sex, breed and size.     

Evaluating Natural Site Formation Processes in Eolian Dune Sands: A Case Study from the Krmpotich Folsom Site,Killpecker Dunes,Wyoming

Eolian dune sands commonly contain archaeological material in both surface and buried contexts. However, because of the dynamic nature of dunes, the original context of an archaeological site can be severely modified or destroyed as a result of post-occupational geomorphic processes. This paper examines a Folsom occupation associated with a buried soil in the Killpecker Dunes in southwestern Wyoming. Field and labortory data are compared to determine the likely scenario of natural site formation processes responsible for the current context of the archaeological assemblage. Two primary eolian stratigraphic units are present at the site, and are separated by the buried artefact-bearing soil. Radiocarbon and optical luminescence ages indicate that the Folsom artefacts occur across a temporal hiatus, and that the buried soil is late Holocene in age. Sedimentological data indicate that the highest frequencies of artefacts by depth are associated with an erosional contact characterized by a concentration of coarse-grained material. Thus, the Folsom assemblage appears to have been vertically displaced as a result of post-occupational erosion and deflation. This case study indicates that evaluating the context of an archaeological occupation in a dune setting is best carried out utilizing multiple lines of evidence derived from both field and laboratory work.     

Where Do Cities Form? A Geographical Agglomeration Model for Europe*

Abstract. In the recent literature on spatial agglomeration models, substantial progress has been made in modeling urban structures in terms of number and size of cities, but the question where cities arise remains unanswered. This paper illustrates that if a spatial agglomeration model is extended with a true geographical dimension, the location of cities can also be endogenized. A geographical agglomeration model for Europe shows that the size and place of cities can be simultaneously determined. The empirical results suggest that elementary economic forces such as agglomeration economies and transportation costs might be able to explain place and size of cities in the long run to a substantial degree. In addition, some new statistical measures of fit are discussed that are needed to evaluate simulations results of this kind.     

Using Multilevel Models to Model Heterogeneity: Potential and Pitfalls

Within the last few years, geographers and researchers in other cognate disciplines with geographic concerns have begun to use multilevel models. While there are several useful existing introductory accounts of these models in the geographical literature, this paper seeks to extend them in three main ways to clarify and emphasize further the substantial opportunities they afford. First, it focuses on how multilevel models are centrally concerned with modeling population heterogeneity as a function of predictor variables. Second, it considers and illustrates a number of specific interpretive issues that can arise when conducting multilevel analyses of place effects. Lastly, it traces some more general, conceptual issues surrounding the use of multilevel models in geographical research. The arguments made are illustrated through an analysis of variations in drinking behavior using data from a typically complex, large‐scale survey; particular attention is given to the inclusion of categorical predictors.