James M. Skibo

The explanation of artifact variability

We furnish a theoretical framework for explaining that portion of formal variability in artifacts attributable to the behavior of the artisan. Major causal factors are the artisans knowledge and experience, extent of feedback on performance in activities along the artifacts behavioral chain, situational factors in behavioral chain activities, technological constraints, and social processes of conflict and negotiation. In identifying the causal factors at work in a specific case, the investigator must focus analytically on activities-that is, on people-people, people-artifact, and artifact-artifact interactions-and on the performance characteristics relevant to each. Application of this behavioral framework allows abandonment of many cherished but unhelpful concepts, including style and function. Ceramic artifacts, the low-fired, clay cooking pot in particular, are employed for illustrative purposes.

Organic tempered pottery: an experimental study

This paper presents the results of testing technological and techno-functional hypotheses concerning the effects of organic temper. Behaviorally relevant tests are used to compare the performance characteristics of untempered, mineral-, and organic-tempered briquettes and vessels. The characteristics tested include impact resistance, abrasion resistance, portability, thermal shock resistance, ease of manufacture, and heating effectiveness. Organic-tempered ceramics have superior performance characteristics during manufacture, allowing for an expedient ceramic technology. This, along with reduced weight and greater portability, may explain the preference for organic-tempered vessels by groups that frequently shift their residence. Moreover, it is found that all low-fired ceramics, but especially organic-tempered ceramics, are susceptible to complete breakdown in a moist environment under freeze-thaw conditions. Frost wedging is thought to be responsible for an underestimation of Late Archaic organic-tempered ceramics in northern latitudes as well as the destruction of any low-fired pottery subject to a moist depositional environment and freeze-thaw cycles.

NEW PERSPECTIVES ON EXPERIMENTAL ARCHAEOLOGY: SURFACE TREATMENTS AND THERMAL RESPONSE OF THE CLAY COOKING POT

This paper examines pottery technology and change through the eyes of the experimental archaeologist. A new vision is presented of experimental archaeology and the role its findings can play in archaeological explanation. It is argued that the most useful results of experimental archaeology are best obtained with long-term research programs. This perspective is illustrated by a case study of the relations between surface treatments (interior and exterior) and thermal performance in cookingpots. The experiments indicate that surface treatments like texturing, organic coatings, and smudging have marked impacts on thermal shock cracking and on thermal spalling in simulated cooking. It is emphasized that the findings of experimental archaeology, expressed as correlates, can be employed in explanations of prehistoric technological change, but only when embedded in more inclusive correlate theories and coupled with the requisite contextual information.

Effects of firing temperature on the fate of naturally occurring organic matter in clays

Abstract Experiments were carried out to test the effects of firing temperature on the fate of naturally occurring organic matter in clay. These results have important applications for the radiocarbon dating of archaeological ceramics. De Atley (1980) originally discussed the effects of carbon derived from coal or other old organic material in clays. Our experiments yielded quantitative measurements of carbon remaining in the ceramic after firing. Two commercial clay compositions were examined; low organic and high organic. Elemental analysis shows that carbon remained in ceramics fired at temperatures of 800–1000°C well exceeding the maximum firing temperatures of most primitive techniques. Organic burn-out is also dependent on the initial percentage of organics in the clay. Similar results for firings in oxidizing and non-oxidizing atmospheres suggest that organic burn-out is not only a combustive process but also a pyrolytic one.

The effects of water on processes of ceramic abrasion

The effect of wet and dry abrasive processes were studied experimentally in order to provide information relevant to studies of ceramic technofunction, use-wear, and non-cultural formation processes. Briquettes of different paste compositions (untempered, fine-sand tempered, coarse-sand tempered) were subjected to tumbling tests using sand, pea gravel, and large gravel abraders in wet and dry modes. Abrasion resistance was indicated by weight loss after 4 h of tumbling; micro- and macroscopic differences in the traces of various abrasive processes were also documented. In every case, wet conditions cause an increase in the rate of abrasion. Explanations are offered for the observed patterns and some implications are drawn for archaeological studies.

Behavioral Archaeology and the Study of Technology

Loneys (2000) recent paper claims that American archaeologists have paid scant attention to the study of technological, especially ceramic, change. We argue that, in fact, interest in such change processes has grown greatly in recent decades and that Loney has overlooked much relevant literature. We support our general argument with a catalog of recent behavioral research on technological change.

Use of a falling-weight tester for assessing ceramic impact strength

Underhill, R. 1939 Social Organization of the Papago Indians. Columbia University Press, New York. Vokes, A. 1983a The Shell Assemblage of the Salt-Gila Aqueduct Project Sites. In Material Culture, edited by L. S. Teague and P. L. Crown, pp. 463-550. Hohokam Archaeology Along the Salt-Gila Aqueduct, Central Arizona Project, vol. 8. Archaeological Series 150(8). Arizona State Museum, University of Arizona, Tucson. 1983b Trash is Trash or Is It? Ms. on file, Arizona State Museum Library, University of Arizona, Tuscon. Voorhies, B. 1973 Possible Social Factors in the Exchange System of the Prehistoric Maya. American Antiquity 38:486489. Wilcox, D. R., T. R. McGuire, and C. Sternberg 1981 Snaketown Revisited: A Partial Cultural Resource Survey. Archaeological Series 155. Arizona State Museum, University of Arizona, Tucson. Wilcox, D. R., and C. Sternberg 1983 Hohokam Ballcourts and Their Interpretation. Archaeological Series 160. Arizona State Museum, University of Arizona, Tucson. Wilmsen, E. N. 1972 Introduction: The Study of Exchange as Social Interaction. In Social Exchange and Interaction, edited by E. N. Wilmsen, pp. 1-4. Anthropological Papers No. 46. Museum of Anthropology, University of Michigan, Ann Arbor.

Sherds as Tools: The Roles of Vessel Fragments in Prehistoric Succulent Plant Processing:

Excavation of an agave-roasting site in southern Arizona disclosed an unexpectedly large collection of sherds. Sherd aggregation and use-alteration analyses were undertaken to determine the role of the ceramics in agave processing. Results indicate that sherds and not vessels were brought to the site, and that sherds may have been used as scoops and possibly as nonflammable covers or receptacles during agave processing. These findings underscore the point that analyses of assemblages of sherds that are not refitted may disregard important information about the nature and organization of prehistoric processing technologies.

Fluvial Sherd Abrasion and the Interpretation of Surface Remains on Southwestern Bajadas

Sherds abraded by fluvial processes are frequently encountered during archaeological surveys, but are most often ignored or misinterpreted. Analysis of sherds within the Ruelas drainage in southern Arizona, and experimental replication of fluvial abrasion, demonstrate how these data can be used in the study of prehistoric land use and settlement location. Under simulated conditions of fluvial transport, sherds are found to abrade in a three-stage sequence. The sherds collected along the Ruelas drainage are placed into the stages of abrasion and a progression of abrasion with increasing distance from the mountains is demonstrated. The origins of these sherds are attributed to sites located farther upstream rather than along the mid-bajada banks of the Ruelas drainage. Experimentation with fluvial sherd abrasion also permits specification of the attributes of transported sherds, contributing to proper field and laboratory identification and thus more accurate inferences about the post-depositional history of surface remains.

Pottery Use-Alteration Analysis

Pottery use-alteration consists of three traces: residue, carbonization, and attrition. An analysis of these traces leads to stronger inferences about actual pottery function. Residue analysis relies on gas chromatography/mass spectroscopy and other available techniques and can inform on the former contents of the vessels. Patterns of external carbonization, or sooting, are created while a vessel is over a fire and depends upon the type of hearth and the methods of cooking. Internal carbonization is created when food inside the vessel is charred and can be used to infer the mode (wet or dry) of cooking as well as aspects about the cooking process. Attrition, either on the interior or exterior of the vessel, can be used to infer a variety of use activities. In this chapter, the various use-alteration traces are reviewed and methods for analysis are outlined.