The artifacts made and used by humans are critical to archaeological work and analysis of past humans’ behavior. Their interpretation and the information they provide largely depends on the environmental conditions to which the artifacts have been exposed, which influences their preservation. This chapter focuses on various kinds of artifacts and specific types of information archaeologists can learn from types of artifacts.
Once artifacts have been excavated, processed in the lab, and catalogued, what happens next? Usually, the artifacts are sorted into broad categories by the types of materials, such as stone (lithics), bone, and ceramic. Once sorted into those initial categories, the categories can be subdivided by other physical attributes such as decorations, color, shape, size and other physical dimensions, raw material sources (e.g., chert or obsidian for stone tools), and manufacturing techniques. These sub-categories can then be further refined until all the artifacts that share similar attributes and/or physical properties are grouped together and define artifact types, creating a typology. Typologies, which were used extensively by archaeologists working under the classificatory-historical paradigm, are thorough visual descriptions of a group of like artifacts. In their analyses, archaeologists often must determine the range of variation that is acceptable when assigning artifacts such as projectile points and arrowheads to a type. Typologies were particularly important tools prior to the development of radiocarbon dating techniques and are still used as a preliminary dating method in the lab and in the field.
Each artifact type is defined by features and attributes archaeologists look for when completing their analyses. Stone artifacts are one of the most studied types simply because of their excellent preservation and longevity. Some of the stone artifacts found in archaeological sites are more than 2 million years old. Stone tools such as projectile points consist of a core stone that will become the tool and a hammerstone that is struck against the core stone to shape it. The tool maker, called a flintknapper, removes large chunks from the core to begin to achieve the rough shape of the desired tool. Often, the first few hits of the hammerstone are designed to remove the cortex of the core, which is the rough outer covering of the rock. The resulting waste flakes are called debitage, and they provide archaeologists with important clues about how the tool was manufactured. After the large pieces of cortex are removed and the artifact is roughly the desired shape, the flintknapper switches to a finer, more-precise method of removing flakes using a softer touch and a softer material such as an antler or other object that applies less force. The debitage produced at this stage is typically called trimming flakes. Each flake (especially larger ones) carries critical information an archaeologist can use to recreate the process by which the stone tool was made. Archaeologists look for the striking platform (where the core was struck) and the bulb of percussion (a raised area formed due to percussion) on the flakes, which indicates the angle and exact point of contact of the hammerstone. Coming off the bulb of percussion are ripples that are similar to ripples made when a stone is thrown into a lake; they extend outward from the point of impact.
Once they understand the process by which an artifact was produced, archaeologists’ next question is what the artifact was used for. The shape and dimensions of stone tools provide clues to their function, but other techniques such as microscopic wear analysis can provide additional information. Different activities, such as sawing back-and-forth motions and downward-angled engraving used for writing produce different marks on the edges of stone artifacts that are clearly visible under a microscope, allowing an archaeologist to perform microscopic wear analysis.
In experimental archaeology, archaeologists try to recreate artifacts using authentic methods and traditional materials. They have expanded our knowledge of ancient processes for manufacturing various types of artifacts. Archaeologists also fit collections of debitage back together like a three-dimensional puzzle to learn more about flintknappers’ processes and craft.
While stone is probably the most studied artifact type, there are many other types of artifacts archaeologists look at. Wood, for instance, was an important material for early tools made by humans based on what we know about current and ethnographic studies of tool materials. Wood was used for tools such as axes and spears, and plant and animal fibers were used to make things like baskets, cordage (ropes), and fabrics. However, as noted in earlier chapters, these types of organic artifacts do not survive for long periods unless deposited in an anaerobic, very hot, or very cold environment so they are much rarer than stone artifacts. Additionally, experimental archaeologists in particular have been able to draw conclusions about ancient organic tools by studying ethnographic artifacts and current makers of those tools (e.g., baskets). For example, the complex weaving rules used in basketry, such as twining versus coiling, and the difference between the warp (the longitudinal or lengthwise run of a fabric or fiber) and the weft (the transverse run of a fabric or fiber that is typically woven in an under-and-over pattern) are well known among weavers working today and archaeologists who primarily study those types of artifacts.
After stone tools, ceramic artifacts are probably the next most studied type. Pottery is typically seen as evidence that a group was sedentary since it is a heavy material. The earliest ceramics date back to the Jomon period in Japan, approximately 14,000 years ago. Pottery has been made using a variety of techniques, including coiling, building pots by hand, and using a potter’s wheel. Archaeologists who focus on the study of ceramics (ceramists) can determine how vessels were manufactured by looking at a piece, sometimes even a small sherd (piece of ceramic) and the firing method. Ceramics can be air-fired or fired in a kiln, and the extent of oxidation, which is the process of organic substances in the clay burning off, provides clues about how a piece was fired.
An important component of manufacturing ceramics and stone tools is the use of fire, or pyrotechnology. In addition to oxidizing, ceramic vessels can be glazed, vitrified, by intense heat. Heat-treating stone is a way to change its physical properties, allowing for thinner, more precise tools to be crafted.
Without fire, it would have been impossible to produce metal tools. Archaeometallurgy is the archaeological study of metal artifacts, which, at the most basic level, are categorized by the type of metal used: non-ferrous metals that do not contain iron and ferrous metals that do contain iron. Of all the non-ferrous metals used by humans in the past, the most important was copper. Copper, which is a soft metal, can be combined with another metal such as tin, creating a stronger alloyed metal (bronze in the case of copper and tin). Metals contain trace elements that allow archaeologists to determine the original source of some artifacts. Additionally, through a metallographic examination in which a piece is examined microscopically, an expert can determine the exact manufacturing technique used to construct the tool. Only after basic heating and manufacturing techniques with metal were understood could more-advanced metal working with the ferrous metals begin. Iron is much more common than copper but could not be used to construct items until people developed smelting, in which iron is heated to a high temperature to remove all impurities, strengthening it.
Once archaeologists understand the basic properties of an artifact and the process of manufacturing it, they can begin to ask questions about human behavior related to the artifact, such as how they traded and exchanged goods. The first step in understanding more about exchange behavior is understanding the source of the artifact in question. Trace analysis, an examination of the chemical signatures of stone and metal objects, points to where the objects came from. Volcanos, for example, produce rocks that have unique chemical signatures. Obsidian produced by an eruption can be traced chemically back to its volcanic source using several methods that can be completed by an archaeologist or in an archaeological laboratory.
Once the source of the material is determined, archaeologists can begin to investigate how the artifact might have ended up where it was found, especially when the source area is not local. When investigating trading, archaeologists typically create a distribution map showing the locations of raw material sources in relation to where such artifacts have been found across the globe (such as all locations where pots with the same design have been found). By graphically identifying all of the locations, archaeologists can investigate patterns to understand how trading worked and if there were more-extensive exchanges and interactions.
Terms You Should Know
- bulb of percussion
- experimental archaeology
- ferrous metals
- metallographic examination
- microscopic wear analysis
- non-ferrous metals
- striking platform
- trace analysis
- trimming flakes
- Describe the role experimental archeology has played in the study of lithics and other classes of artifacts.
- Select one artifact class (i.e., stone, ceramic, metal) and describe the main components or attributes archaeologists look for when analyzing that type of artifact.
- What is the difference between ferrous and non-ferrous metals?
- Why is the study of debitage important to archaeologists?
- What insights can trace analysis provide in an archaeological analysis?