Part of the archaeologist's job is to distinguish changes in time, function, and style of artifacts.
Polly Wiessner studies variation in artifacts, focusing on style.
Among the San of southern Africa, she examined the differences in the style of arrows.
Most of the hunters could identify their own arrows and those of their close colleagues.
Wiessner determined that there were clear distinctions between the groups in arrows.
Classification is the primary means for categorizing large bodies of data.
Archaeologists also use statistics and graphs to summarize and display the data they compile.
A major part of archaeology consists of searching through a huge body of material and information for more facts.
Analysis is the study and search for pattern in the body of information that results from excavation and classification.
Presentation and comparison of data are best accomplished with the use of statistics to summarize and display the information of relevance.
Statistics provide descriptive measures of average and range.
Statistics are also useful for making decisions about similarities and differences in numbers using probability.
The visual display of data is another way to condense information and make it more understandable.
Cleaning and Cataloging
When the finds come in from the field, they have to be processed, which involves a number of steps.
Materials first need to be cleaned so they can be analyzed.
Preventing mold and fungus growth is also important.
Cleaning is usually done with water and brush.
Most finds are also cleaned so they can be numbered and cataloged.
Artifacts and ecofacts are typically numbered.
Numbers are usually applied in permanent ink.
Archiving the finds according to a logical system is essential.
Finds are entered into a catalog of permanent records.
The catalog entry for each object includes a detailed description.
This catalog could be supplemented with an accurate drawing and a photograph of the find.
Once the artifacts and other finds have been cataloged and the analysis is done they are stored in a museum or other appropriate facility.
Conservation
The conservation of archaeological materials is critically important, yet often neglected.
Less durable artifacts begin to decompose when removed from their original burial conditions.
Conservation is essential to preserve these items.
There are few trained conservators or facilities for this kind of archaeology in the U.S.
Conservation involves two primary activities: preservation and restoration.
Preservation involves stabilizing the condition of the finds through the use of mechanical and chemical means.
Conservators prefer to preserve items, rather than restore them, in most instances.
The goal of conservation is "Non-Toxic, Minimal Intervention Artifact Stabilization."
Conservation treatments for artifacts can be active or passive.
Active preservation involves using various means to repair the object and improve its stability.
Passive treatments seek to improve the conditions under which the find is held in order to prevent further deterioration.
Passive conservation is more cost effective since a large number of finds can be stored under similar conditions of preservation.
Documentation of treatment is an essential part of conservation.
Example: Lindow Man
Among the most remarkable prehistoric bodies are the "bog people" from northern Europe.
Hundreds of individuals have been found in the peat bogs, dating to the centuries around the birth of Christ.
These bogs have marvelous preservative powers.
Lindow Man is one of the bog bodies, found near Manchester, England.
The finds included the head, torso and right foot of a male in his twenties.
Radiocarbon dates from the body indicate a date of death between the birth of Christ and AD 120.
Lindow Man was bludgeoned with an axe, strangled, and his throat was cut before he was placed in the waters of the bog.
Lindow Man also provides an extraordinary example of the innovative techniques of archaeological conservation.
Fifty specialists were called in to examine Lindow Man.
They dated him, X-rayed him, analyzed his stomach contents, determined his blood type, checked his teeth, and reconstructed his face.
After the analyses, the standard sequence of conservation treatments began.
Within a few months of his discovery the Lindow May began to deteriorate, so special preservation techniques were used.
Classification
Following the initial cleaning, recording, and conservation of materials, finds are classified into more specific categories and types.
Classification is a way of creating order in a mass of archaeological materials by grouping items into similar categories for analysis.
Classification is the process of putting objects into groups on the basis of shared characteristics.
Archaeologists often distinguish between splitters and lumpers.
Classification is not an objective process and classifications are not rigid or necessarily right.
Classifications are developed to solve a problem, to answer specific questions.
Classification proceeds through steps, creating hierarchies of categories.
Some objects readily fall into categories and can be easily classified, while others do not.
Most classification systems are either intuitive or objective.
There are several important concepts involved in classification.
Grouping is the process of sorting things into groups of similar items without predetermined categories.
A typology is a formal system of classification for assigning time and space meaning to archaeological materials.
Guides and keys are aides for identifying items.
Classifications of archaeological material are usually hierarchical, ranked from more general to more specific.
Hierarchical classification creates a kind of family tree of artifact types.
Classifications are considered today as arbitrary frameworks for categorizing materials to bring order to chaos.
This has not always been the case.
Classification is important in archaeology for several reasons.
Sorting provides some order to the mass of materials that are recovered.
Description of archaeological materials is less dense and tedious when reference is made to an existing known category or type.
Classification greatly facilitates comparison of assemblages or sites.
Archaeological Thinking: Iroquois Pottery
Iroquois Pottery provides an example of how classification can occur with respect to ceramics.
Classifying Artifacts
The major differences among prehistoric objects are normally due to variation in raw material, technique of manufacture, function, and style.
Raw material involves the basic properties of the material and where it came from.
Artifacts are shaped from a raw material using a certain technique for an intended purpose.
Use of an artifact may leave distinctive traces of wear, damage, or residue.
Some characteristics of an object may be due to errors in manufacture.
Items may have other distinctive features related to style.
Identifying major characteristics is often difficult, as an artifact frequently combines several of these characteristics.
Raw Materials
In the past, the available raw material was largely limited to what nature provided.
Raw material is a fundamental criterion for separating categories of material in archaeology.
Substances were selected as appropriate for the intended use of an object.
Raw material availability and selection is an essential aspect of early human behavior. Transport and exchange of raw material documents the importance of various materials. Raw material is usually one of the more obvious characteristics of an artifact.
Technology
Technology is a combination of technique, or method, and knowledge, or skill.
Production technology is an important feature of any artifact.
The evolution of technology in human history takes place at an ever-increasing rate.
Manufacturing techniques can be either additive or subtractive.
Function and Style
Function refers to the purpose of an artifact.
Archaeologists often "explain" an artifact by stating its function, and distinguish function from style.
However, objects can have several different purposes.
Style is a more difficult concept.
We all know what it means but it is hard to define.
Style is a distinctive way of being something.
Style can be shared among a group of people as a learned way of doing things.
Style can also be a recognized emblem of group membership.
Variation in Time
Groups of similar items vary in time and geographic space.
Style and time are intimately related in archaeological typologies.
Style usually provides the most information on change over time and variation over space in archaeology.
Function changes more slowly.
Archaeological Thinking: Styles of Gravestones
James Deetz studied the designs on gravestones in New England to understand changes in style over time.
Deetz recorded the type of design and year from a large number of graves.
He distinguished three major motifs.
Archaeological Thinking: Seriation
Before the advent of absolute dating methods, it was difficult for archaeologists to determine the age of their finds.
A new method to establish the chronological order of archaeological finds involved dating by association.
Flinders Petrie laid the groundwork for this method.
Frequency seriation is one in which an archaeologist orders a series of artifact assemblages based on the relative frequency of types in each assemblage.
This is usually done with ceramic assemblages.
Charts called "battleship curves" represent the popularity of a style across time.
Variation in Geographic Space
Types also vary in geographic space.
Examining the extent of types provides information on the distribution of the human groups that made and used that type and helps to identify exotic or unusual finds.
This spatial information is an important aspect of archaeological knowledge.
Data
Data are information, usually in the form of numbers, which are created and collected in archaeological research.
Data are created when we observe, count, or measure.
Data are often recorded as numbers, although other kinds of information (words and images) can also be data.
Numbers
Numbers are a way of simplifying the world around us.
Numbers can be presented in different ways: counts, percents, or measurements.
Percentages are useful for comparing amounts of specific items from different contexts or places.
The three common scales of measurement used for recording data are nominal, ordinal, and ratio.
Nominal scales record basic information as unordered observations.
Ordinal scale data is ranked information.
Ratio scale measurements are values with a true zero point.
There is a distinction between qualitative and quantitative numbers is also useful.
Qualitative data are determined subjectively or judgmentally and include nominal and ordinal scales of measurement.
Quantitative numbers are measured by comparison to a fixed or known scale using tools or instruments.
Basic Statistics
Statistics involves techniques for summarizing and manipulating data.
The end goal is to make sense of numerical information.
Statistics can be either descriptive or inferential.
Mean, Median, and Mode
Mean, median, and mode are different ways to express the concept of average in data using a single number.
The mean is the average measure for ratio scale data.
The median defines average by locating the exact middle number of the ordered values.
The mode is the most common category of number in the set of the data.
Range, Variance, and Standard Deviation
There are several ways to express the spread of measured values.
Range is a simple measure of the spread of a set of values using two numbers, the highest and lowest values.
The variance is the sum of the difference between the mean and each data point squared divided by the number of observations.
The standard deviation is simply the square root of the variance.
The Normal Curve
The normal curve involves the shape or distribution of the values of a quantitative, ratio scale variable.
The normal curve (or bell-shaped curve) describes the standard, or normal, shape of measured values on virtually any variable.
Continuous variables usually show a normal curve when enough measurements are plotted on the graph.
There are lots of uses for the normal curve.
Chi-Square and Contingency Tables
Archaeologists often want to compare two groups of things.
Chi-square compares what we observe in the data to what we would expect if there were no differences between the two groups.
Chi-square is used only with nominal scale data.
Visual Display of Information
There are several ways to display information.
A table is a standard method for listing information and works fine if the amount of information is low.
A good way to approach a lot of information is to use graphs.
There are several kinds of graphs.
Stem and Leaf Plots
A stem and left plot displays numbers from a tally to form in the form of a diagram.
Bar Graphs and Histograms
Bar graphs and histograms are useful means to display data.
A bar graph is basically a tally sheet with bars instead of tally marks.
A histogram is a bar graph for ratio scale information and shows how measurements are spread over their range of values.
Box and Whisker Plots
A box and whisker plot is the name for a graph that shows five summary measures in a single figure.
The five summary measures include the median, the quartiles, and the minimum and maximum values in the distribution.
Pie Charts
A pie chart shows the distribution of information as slices of a circular pie.
The width of each slice of the pie is determined by the proportion of each item in the whole.
Scatterplots
A scatterplot is a graph that allows you to look at two sets of numbers simultaneously.
Each dot on the graph represents one sample or one pair of measurements.
