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- Lab 9 Notes Fall 1997
Archaeology is the study of both modern and ancient societies which emphasizes the relationship between artifacts and human behavior in all times and places. The complex behaviors of humans and our recent ancestors leave many kinds of traces on the world, and archaeologists can make statements about past behavior by a careful consideration of the artifacts they recover. An artifact is anything which exhibits any physical attributes that can be assumed to be the results of human activity, including the activities of early Homo (Dunnell 1972). Artifacts can be pieces of fire cracked rock, gold cups, jade beads, pyramids, brick walls, broken pots, dinner leftovers, sharpened sticks, stone tool debris, plowed fields, lawns (and the random paths that crisscross them), or even polluted streams. Because artifacts are tangible, they can be analyzed with standardized tests and measures.
Unfortunately, the vast majority of artifacts do not preserve long enough for analysis. Consider the tools used by chimpanzees. Of the 19 known tool types, perhaps only one or two would survive even a month in the tropical rainforest. An archaeologist would probably not find termite sticks, water soaking leaves, or nut cracking branches.
In order to infer human behavior from artifacts, archaeologists must be able to interpret behavior from the characteristics, or attributes, of artifacts – to reconstruct stone toolmaking from manufacturing debris, hunting and butchering techniques from animal bones, or trading patterns from the distribution of manufactured goods. In describing the formal characteristics of artifacts archaeologists may measure certain attributes, such as size, shape, weight, color, texture and other surface treatments, plasticity and elasticity, composition, and arrangement of parts to name a few.
Sampling
All archaeological recovery is sampling, that is archaeologists select from among the total possible regions and sites areas to be surveyed and, within sites, those areas to be excavated. There are several practical reasons for deriving samples from the archaeological record. 1) the archaeological record is a non-renewable resource and every site and every artifact is a unique phenomena. When archaeologists collect data through excavation, they destroy that portion of the site. Sampling strategies allow the archaeologist to systematically collect data from a site and assume that their sample is representative of the whole set of materials present at the site. Archaeologists, then, do not have to excavate the entire site, and in doing so removing it from the archaeological record. 2) excavation is expensive. A good sampling strategy allows archaeologists to concentrate their resources to address particular research questions.
The whole set of materials within a study area is called a population. Any part or subset of a population is a sample, and each member of the population is a potential sample unit. There are several sampling strategies available: 1) purposive, where there is a set of specific criteria which members of a population must meet in order to be included in a sample, for example selecting fruit based on color, firmness, and size; 2) haphazard, where there is no guidance system; 3) simple random sampling, where each member of a population has an equal chance of being included. This technique often involves assigning a number to each member of a population and using a random number generator to select sample units (Rathje and Schiffer 1982).
Stone Tool Production
Stone tool, or lithic, analysis (from the Greek word lithos or stone), is an important component of archaeological analysis because 1) stone preserves well in archaeological deposits and is present on most prehistoric sites; 2) tools provide information concerning the types of activities that might have occurred at the site; 3) exotic material types might give an indication of contact or trade with neighboring groups; and 4) increasing complexity in stone tool manufacture might indicate increasing cognitive ability in early Homo species.
Lithic artifacts can generally be broken down into two types based on manufacturing technique: chipped stone artifacts and ground stone artifacts. Chipped stone artifacts are those formed by removing pieces of stone from a block of parent material. Forming a chipped stone tool usually requires several stages of manufacture and the use of several kinds of percussion or pressure tools. Hard-hammer percussion is a technique in which one stone, the hammerstone, is struck on a second stone to produce flakes which tend to be large and relatively thick with prominent morphological features. Early Homo species used this technique to strike flakes off cobbles to create a jagged but sharp cutting or scrapping edge.
Another chipping technique is soft-hammer percussion where a baton of resilient material, such as bone, wood, or antler, is used to strike off flakes. Because a soft-hammer blow does not remove a large mass of material, it is usually used to trim and shape flakes into more finely finished tools. The last major technique is pressure flaking where force is applied indirectly though another tool to detach small, thin flakes, usually to resharpen cutting edges or to do fine finishing and shaping tasks.
Analysis of the manufacturing debris, called debitage, can provide insights into the size and shape of material used in tool manufacture as well as how the tool manufacturing system was organized. The morphology of a flake can provide clues to its position in a manufacturing sequence and to the type of flaking technique used to produce it. The platform is the surface at the proximal end of the flake where force was applied to detach the flake. A platform can be strengthened by grinding, polishing, or faceting usually in order to detach a larger flake. The point of force, or lip, is the actual point of contact between the hammerstone and the flaked piece. Soft-hammer percussion and pressure flaking techniques often create prominent points of force. The bulb of applied force is on the ventral side at the proximal end of the flake. Hard-hammer percussion tends to create a prominent bulb of applied force where soft-hammer percussion and pressure flaking techniques tend to create a relatively flake bulb of applied force. Ripples are created by compression rings that travel through the solid as a result of percussion (Crabtree 1972).
The sharp edges of a detached flake can also serve as tools and the traces of wear that occur during use can often be detected. Several major kinds of such wear include microflaking, striations, and polish. Microflakes are tiny flake scars that can be seen on a tool’s edge. Scraping motions tend to produce flaking only on the dorsal side, the side away from the scraped surface, of a tool edge. Cutting motions produce flaking on both sides. Striations are scratches formed by abrasion. The orientation of striations on tools indicates the direction of motion during use. Polish is a high-reflectance area on a edge caused by abrasion with a coarse surface.
The angle of the tool’s working edge, or edge angle, also provides clues to use. Tools with an acute angle (less than 35o) seem to have resulted from cutting soft materials such as skin or muscle. Tools with edge angles greater than 60o were used for cutting or scraping hard materials such as bone and wood. Tools with intermediate angles (35-40o) were possibly used as knives.
Ground stone artifacts are created by using a stone to from another stone into a tool by grinding smooth surfaces and/or facets for cutting surfaces.
The earliest recognized tool making tradition is associated with early Homo. These artifacts are called the Oldowan tool industry after the site where they were first recovered. They consist of rounded river cobbles which have been flaked along one side, using hard-hammer percussion, to produce a cutting edge. Several tool types have been identified including, bifacial choppers, heavy-task scrapers, hammerstones, and debitage with evidence of use wear (Leaky 1971).
The planning and foresight required to make a stone tool represents an enormous cognitive leap from the stick tools and crushed leaves of the chimpanzee. Lithic tool production requires the fabricator to have a knowledge of rock mechanics, that is, to be able to predict how a solid form will fracture given a certain amount of force. Not all rock types are suitable for flaking, especially those coarse grain igneous rocks, the fabricator must know where to find The fabricator must be able to control the force she uses and the striking angle between the hammerstone and the raw material. Most importantly, since lithic tool production is a reductive technology, the fabricator must have an mental of the type of tool he wants even before he starts taking off flakes.
2) Faunal Analysis
Faunal or animal bone data are used to describe a variety of behaviors, such as the prominence of different species in the diet; hunting, butchering, and cooking practices; season of occupation of settlements; past environments; trade patterns; and ritual uses of animals. Inferences about how early Homo used procured meat depends, in part, on knowledge of animal behavior in specific environments. Knowledge of animal behavior is required for inferences about the season of occupation of settlements. Bones from migratory fish, for example, would be clues as to when during the year fishing activities, and probably occupation took place.
The first models of early Homo subsistence patterns assumed that since these ancestor’s used tools and had big brains they must have been hunters. Males went out into the savanna looking for game while females stayed at the base camp or gathered roots nearby with their young. This argument was supported by the discovery of stone tools in association with fossil animal bones at sites such as Olduvai Gorge. Is this assumption warranted?
Reconstructions of ancient diets requires some knowledge of the amounts of meat usually obtained from different kinds of animals. Faunal analysts have estimated the ratio of meat weight to total animal weight and, by estimating the number and species of animals present at a site, the weight of meat obtained can be inferred.
The hard part is estimating the number of animals on the site that had to be present in order to account for the archaeologist’s faunal assemblage. There are several methods used to estimate the size of a faunal assemblage three of which are the number of identified specimens (NISP), the minimum number of individuals (MNI), and minimal animal units (MAU). Each system has strengths and flaws.
Number of Individual Specimens (NISP)
For many years, the NISP per species was used as the standard measure of abundance within archaeological faunal assemblages. The NISP value is obtained by simply adding all bones or bone fragments belonging to the same species. For example, a faunal assemblage with 49 deer specimens and 51 bison specimens equals a NISP of 49 for deer and 51 for bison.
Archaeologists have used NISP to estimate the size of the death population, to estimate animal weights, and to analyze changing taxonomic frequencies through time and across space. However, specimen counts do have some severe drawbacks (Grayson 1984).
1) NISPs are affected by butchering patterns. Large animals, like bison, which are too heavy to carry may be dismembered at a kill site and while the hunters may remove the pieces with the most meat, they may leave behind parts with little meat including skulls, metatarsals, metacarpals, vertebrae, and pelves. Small animals, like deer, may be removed entirely from the kill site.
2) NISPs vary from species to species and differences in numbers of specimens may simply reflect the fact that an analyst can easily identify all the specimens belonging to a bison but can only identify the cranial elements and teeth of a rodent to the same taxonomic level.
3) Differential preservation of bones may imply that the NISPs identified by an archaeologist today may have no relationship to the number of bones originally deposited. If the bones of 51 bison were deposited in the ground but the bones of only 14 individuals survived to the present, then an archaeologist might assume that only 14 individuals were ever there.
Minimum Number of Individuals (MNI)
MNI is simply a measure of how many animals of a given species must have been present within an archaeologically defined area to account for the faunal assemblage. For example, if there are 10 left and 16 right bison tibiae in a site, there must have been at least 16 bison present at some point. Many of the above problems associated with NISP counts are also true for MNI counts.
Minimal Animal Units (MAU)
Several alternative specimen counting measures have been proposed to replace NISP. Ethnoarchaeologial studies have shown that meat is not treated by people in units of single animals, but instead in units of animal segments. Hunters and scavengers are generally not interested in the entire body of animal but usually only select what they believe as the most useful segments. "Useful" segments include not only meatiest portions of the animal but also economically important segments such as skin, sinew, and ligaments and perhaps socially significant segments as well. MAU values are important for subsistence studies because they emphasize they selective aspect apparent in hunting and scavenging behavior.
The MAU value is calculated by dividing the total observed bone count by the number of bones in the anatomy of a complete animal for that unit. For example, in a collection of 70 right and 30 left femora for a given species, there would be a MAU of 50; that is, 100 femora divided by the number of femora that occur in the skeleton.
One problem with the MAU value is that vertebrae and phalanges are difficult to account for (Grayson 1984). For example, how many segments are accounted for by 80 first phalanges from an animal, such as a deer who has eight of these elements? If it is that particular phalanx then the MAU is 80 (80ö1=80). If the forelimbs and the hindlimbs are treated separately then the MAU is 20 (80ö4=20). If all phalanges are used together then the MAU is 10 (80ö8=10). This measure is more appropriate for bones which are only represented once in a skeleton, for example, femora, tibiae, or humeri.
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