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Introduction Archaeology is the study of the human past, combining the themes of time and change. Time The Earth was formed about 4.6 billion years ago. Life emerged around 4 billion years ago. Geological Time Consider the 4.6-billion year history as a single week, with each day representing about 650 million years. If the Earth formed on Sunday morning, then life emerged by Sunday evening. By 11:00 a.m. on Saturday morning, the last day of the week, life was present on land. Ancestors to mammals appeared after 9:30 p.m. The first human appeared at 11:49 p.m. Agriculture and animal domestication originated just 2 seconds before the end of the week. Geological time is broken down into a series of eras, representing major episodes. The Precambrian runs from the beginning of the earth to about 600 m.y.a. The Paleozoic witnessed the appearance of the first vertebrate species. Around 225 m.y.a., the Mesozoic era, or the Age of the Dinosaurs, began. The current era, the Cenozoic, began about 65 m.y.a., after the extinction of the dinosaurs. The Cenozoic is divided into a series of seven epochs, the last four of which are relevant to humans. The Miocene was from 24 to 5.5 million years ago. During the Pliocene, a variety of hominid fossils, humanlike creatures, appeared. The Pleistocene began around 2 m.y.a. The most recent epoch is called the Holocene and began around 11,000 years ago. Change Change can occur through both biological and cultural processes. Most of the evolution of life on earth is characterized by biological evolution. Culture is a means of human adaptation based upon experience, learning, and the use of tools. The prehistoric record of our ancestors is characterized by both biological evolution and cultural developments. Our first several million years of existence were dominated by biological change. The transmission of cultural traits occurs more rapidly than biological ones. The last one hundred thousand years or so are marked primarily by cultural changes. This is the story of archaeology – the search for evidence of our cultural development through time. Biological Evolution Charles Darwin and Alfred Wallace were the first to describe the process of natural selection. They noted that individuals with variations that allowed them to survive and reproduce did so with greater frequency, thereby increasing the frequency of those variations in subsequent populations. The Discovery of Archaeological Sites Discovery can occur in many different ways, however, most sites are discovered by chance. Digging and construction often uncover prehistoric objects. Amateur archaeologists often know about local history and frequently find sites while walking fields. Besides chance discoveries, fieldwork can be used to locate sites. Several steps are often taken prior to beginning site discovery fieldwork. Archaeologists can rely on relevant written material to learn about the time and place of interest, and what is presently known. Visiting local historical societies or museums can provide further information. The use of maps is important for identifying the location of sites. Fieldwork is the next step in discovering the past. An archaeological survey is a systematic search of the landscape for artifacts and sites. The basic type of field survey involves systematic walking of the site for the purposes of obtaining artifacts or locating features. When artifacts are found, they are stored and information about them is recorded. Once buried sites have been located, other kinds of fieldwork can be undertaken to learn more about them. Boring into the ground can reveal the sequence of layers and sediment samples at the site. Small test pits can be made to provide similar information. Soil analysis can yield important information. Chemical analysis can provide information about environmental factors at the site. Phosphate analysis may reveal traces of human activities. Objects in the soil can also provide important information. Other techniques can be used prior to excavation to find out about the site. Geophysical prospecting can be used to detect disturbances in the subsoil and the presence of prehistoric features. Ground penetrating radar is becoming a standard in the field. Archaeological Excavation Excavation is the technique used to uncover buried remains from the past. Buried materials are usually more abundant and better preserved than those found on the surface. Excavation is often essential to obtain more information about the past. Excavations are conducted to answer specific questions framed by the archaeologist. The Excavation Director oversees the operations of an excavation. Many skills are required to direct excavation, including knowledge for planning, raising money, supervising the crew, and recording information. The Field Crew is the most important part of an archaeological project. Excavation is labor-intensive. The crew is involved with the actual digging process. Crews can be composed of a variety of individuals. Fieldwork can require months of labor. Selecting sites for excavation involves several factors. Sites threatened by modern construction are often good candidates for excavation. Sites are also chosen because they are well preserved or contain information that will aid the understanding of a particular region or time. The choice of a site is often based upon the results of a survey. Creating maps and grids during excavation is essential. Accurate mapping of layers and artifacts is the key to the proper recording of information. A grid is marked out across the surface of a site prior to excavation. Reference points need to be established. Test pits are often made to provide a preliminary examination of a site. Sometimes test pits are placed in a systematic fashion and sometimes they are random. The size and number of pits depends upon the information being sought. Vertical excavations take the form of pits or trenches placed across a site. The stratigraphy, or layers, reveal how the site was formed and how materials accumulated. The bottom layer is typically the oldest. Evaluation of a stratigraphic sequence involves distinguishing between natural and human activities. Assessment of the layers allows for the interpretation of the history of the deposits. Horizontal, or area, excavations often follow vertical excavations and expose large areas of ground. Area excavations are intended to recover information on site arrangement and structures. Actual prehistoric living floors may be exposed. As layers are removed, information about each one is analyzed and recorded. Analysis of Archaeological Materials Archaeological material needs to be analyzed after collection. Analysis can occur concurrently with fieldwork in a field laboratory, or later at a home laboratory. More detailed analysis includes the preparation of reports and publications which require much more time. Final results are available to the public and to professional archaeologists. A variety of specialists is required to examine and interpret the finds and information derived from fieldwork. Fieldwork can yield artifacts, ecofacts, features, sites, and settlements. There are specialists in such areas as archaeobotany, archaeozoology, paleoanthropology, and many others. There are also specialists in certain classes of materials. Fieldwork yields portable objects altered by human activities, called artifacts. Artifacts must be cleaned and recorded. A catalog description of each artifact includes many pieces of information, such as form, technology, and style. A description could include a drawing or picture. Classifying the artifacts into specific types can create order. Ecofacts are unmodified natural items, such as animal bones and plant remains. Ecofacts are usually brought to the site by its occupants. They are used to reconstruct the environment of the site and the range of resources that people used. The study of plant remains can provide information about past environments. Analysis of animal remains can yield information about what animals were eaten and how meat was obtained. Features are immovable structures, layers, pits, and posts in the ground. Features are typically studied in the field since they are fixed in the ground. They are useful for understanding the distribution and organization of human activities at a site. Some features result from the accumulation of garbage and debris, rather than being intentionally crated. Burials and human bones are a special category of feature often found at archaeological sites. Sites and settlements are the sets of artifacts, ecofacts, and features that define places in the landscape where activity and residence were focused. Investigations range from the analysis of the location of different activities within a single room to the distribution of sites in a region. Spatial patterning within a site can provide information about the number of houses and people at the settlement and their relationships with one another. Regional settlement patterns can provide a variety of information on the use of the landscape. Interpretation of Archaeological Information The science of archaeology lies in bridging the gap between the information recovered through excavation and the questions being sought. Information recovered from the ground does not directly say very much about the past. Analysis may provide some basic information. However, the questions sought are often much larger. The questions that archaeologists seek to ask are highly varied. Some may be very specific. Some may be much more general. Some questions and ideas come from the knowledge of living peoples, derived through ethnographies. Explaining human behavior in the past and its changes through time is a major goal of archaeology. Archaeological theories and ideas are attempts to explain what took place in the past. What makes archaeology a science is its rigorous testing or evaluation of answers to questions being asked. Archaeologists ask questions about past societies that involve concepts of technology, economy, organization, and ideology. Technology is the manner in which people convert natural resources into products they need or want. Economy is a broad topic that involves how people obtain foods, materials, and goods to sustain their lives. Organization refers to the roles and relationships in society on a variety of levels. Ideology refers to the means by which people structure their ideas about the universe, their place in that universe, and their relationships with one another.
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