Archaeology
Archaeology- pronounced ahr kee AHL uh jee, is the scientific study of the remains of past human cultures. Archaeologists investigate the lives of early people by studying the objects those people left behind. Such objects include buildings, artwork, tools, bones, and pottery. Archaeologists may make exciting discoveries, such as a tomb filled with gold or the ruins of a magnificent temple in the midst of a jungle. However, the discovery of a few stone tools or grains of hardened corn may reveal even more about early people.
Archaeological research is the chief method available for learning about societies that existed before the invention of writing about 5,500 years ago. It also provides an important supplement to our knowledge of ancient societies that left written records. In the Americas, archaeology is considered a branch of anthropology, the scientific study of humanity and human culture. European archaeologists, however, think of their work as most closely related to the field of history. Archaeology differs from history in that historians mainly study the lives of people as recorded in written documents.
Archaeologists look for information about how, where, and when cultures developed. Like other social scientists, they search for reasons why major changes have occurred in certain cultures. Some archaeologists try to understand why ancient people stopped hunting and started farming. Others develop theories about what caused people to build cities and to set up trade routes. In addition, some archaeologists look for reasons behind the fall of such early civilizations as the Maya in Central America and the Romans in Europe.
What archaeologists study
Archaeologists examine any evidence that can help them explain how people lived in past times. Such evidence ranges from the ruins of a large city to a few stone flakes left by someone making a stone tool long ago. The three basic kinds of archaeological evidence are
(1) artifacts(2) features, and (3) ecofacts.
Artifacts are objects that were made by people and can be moved without altering their appearance. Artifacts include such objects as arrowheads, pots, and beads. Artifacts from a society with a written history may also include clay tablets and other written records. Features consist mainly of houses, tombs, irrigation canals, and other large structures built by ancient peoples. Unlike artifacts, features cannot be separated from their surroundings without changing their form. Ecofacts are natural objects found with artifacts or features. Ecofacts reveal how ancient people responded to their surroundings. Examples of ecofacts include seeds and animal bones.
Any place where archaeological evidence is found is called an archaeological site. To understand the behavior of the people who occupied a site, archaeologists must study the relationships among the artifacts, features, and ecofacts found there. For example, the discovery of stone spearheads near the bones of an extinct kind of buffalo at a site in New Mexico showed that early human beings had hunted buffalo in that area.
If objects are buried deep in the ground, their position in the earth also concerns archaeologists. The scientists study the layers of soil and rock in which objects are found to understand the conditions that existed when the objects were placed there. In some places, archaeologists find many levels of deposits called strata. The archaeological study of strata, called stratigraphy, developed from the study of rock layers in geology.
How archaeologists gather information
Archaeologists use special techniques and equipment to gather archaeological evidence precisely and accurately. They also keep detailed records of their findings because much archaeological research destroys the remains being studied. Locating sites is the first job of the archaeologist. Sites may be aboveground, underground, or underwater. Underwater sites include sunken ships as well as entire towns that have been submerged because of shifts in land or water level. Some large sites are located easily because they are clearly visible or can be traced from descriptions in ancient stories or other historical records. Such sites include the pyramids in Egypt and the ancient city of Athens in Greece. Some less obvious sites have been discovered accidentally by non archaeologists. In 1940, for example, four children in search of their dog found the Lascaux Cave in southwestern France, which has prehistoric wall paintings. Many important discoveries have been made by archaeologists who searched tirelessly over many years for a specific site or type of site. Working in this way, an English archaeologist named Howard Carter discovered the treasure-filled tomb of the ancient Egyptian king Tutankhamen in 1922. Archaeologists use systematic methods to discover sites. The traditional way to find all the sites in a region is through a foot survey. In this method, archaeologists space themselves at measured distances and walk in preset directions. Each person looks for archaeological evidence while walking forward. Archaeologists use this method when they want to know where sites do not occur as well as where they do. For example, they might use it to confirm that sites in a particular region occur on hilltops but never in valleys.
Archaeologists use scientific methods to help discover underground sites. Aerial photography, for example, can reveal variations in vegetation that indicate the presence of archaeological evidence. Plants that are taller in one area of a field may be growing over an ancient grave or irrigation ditch. Plants that are shorter in another area may be growing in shallow ground over an ancient building or road. In addition, simple metal detectors can be used to sense metal artifacts that have been buried as deep as 6 feet (1.8 meters).
Surveying sites Archaeologists begin to study a site by describing it. They make detailed notes about the location of the site and the kinds of evidence visible on its surface. They also take photographs of the site.
Archaeologists make maps of most sites they find. The type of map drawn depends on the importance of the site, the study’s goals, and the amount of time and money available. In some cases, simple maps are made after pacing off distances or using a measuring tape. In other cases, special instruments are used to survey the site carefully and draw detailed maps.
After making a map, the scientists collect artifacts from the surface of the site. They divide the surface into small square areas and examine one area at a time. The locations where artifacts are found are recorded on the map. Some surface artifacts can give information about when or how a site was used.
Excavating sites. Archaeologists dig carefully for buried objects in a process called excavation. The method of excavation depends partly on the type of site. For example, archaeologists working in a cave might divide the floor and the area in front of the cave into small square units and then excavate each unit separately. Archaeologists working on a temple platform might dig a trench into the front part of the platform and extend the trench into the ground next to the platform. At large sites, excavation may be limited to certain areas. Other considerations that frequently determine the excavation method include the climate and soil at the site.
Tools used in excavation range from tractors and other heavy equipment to small picks and paint brushes. In some cases, the scientists strain soil through wire screens to recover extremely small objects. In other cases, they analyze soil in a laboratory to detect either grains of pollen or chemical changes caused by human remains. Working underwater. Archaeologists who work underwater use many methods adopted from land archaeology. Aerial photography over clear water may reveal the outlines of sunken harbors and towns. A method called sonar scanning helps detect underwater objects by the reflection of sound waves. In addition, divers use metal detectors to uncover metal objects. Photographic maps of sites can be made from submarines or by divers carrying underwater cameras. Archaeologists work at underwater sites in submersible decompression chambers. They use balloons to raise large objects to the surface for further study.
Recording and preserving evidence. Archaeologists describe, photograph, and count the objects they find. They group the objects according to type and location. For example, broken pieces of pottery, called potsherds, are bagged together by excavation unit and level. This collection then goes to the field laboratory to be cleaned and labeled. At the field laboratory, special care must be taken to preserve objects made of such materials as metal and wood. For example, rust on a metal object must be removed without damaging the surface. Water-soaked wooden objects may crack or lose their shape when exposed to the air. These objects must be kept wet until specialists called conservators can preserve them.
How archaeologists interpret findings
Archaeologists follow three basic steps in interpreting the evidence they find:
1) classification, (2) dating, and (3) evaluation.
Classification. Archaeologists can interpret their findings only if they can detect patterns of distribution of artifacts in space or through time. To find these patterns, archaeologists must first classify artifacts into groups of similar objects. The two main systems of classification are typology and seriation. In typology, objects are grouped according to what they look like, how they were made, and how they were used. Each group of objects is called a type. For example, all the pottery jars from a site that look alike represent one type, and other jars represent other types.
In seriation, all objects of one type are arranged in a series that reflects changes in style. These changes either developed gradually as time passed or as a culture spread to other areas. In many cases, the age of the objects must be known to determine which is the first and which is the last member of a series. Dating of archaeological objects is called archaeometry. The methods of archaeometry can be divided into two major types:
(1) relative dating and (2) absolute dating.
Relative dating gives information about the age of an object in relation to other objects. Thus, relative dating methods produce only comparisons, not actual dates. For example, archaeologists can determine the relative ages of bones found at a site by measuring their fluorine content. Fluorine from underground water gradually replaces other elements in bones, and so older bones contain more fluorine. Absolute dating determines the age of an object in years. There are many absolute dating methods. The method used in a specific case depends mainly on the type of object being dated.
The most widely used method of dating the remains of ancient plants, animals, and human beings is radiocarbon dating. This technique is based on the fact that all living things constantly absorb two kinds of carbon atoms, carbon 12 and carbon 14. Atoms of carbon 14, also called radiocarbon, are unstable and change into nitrogen atoms at a known rate. After an organism dies, therefore, the ratio of carbon 14 to carbon 12 also decreases at a known rate. As a result, archaeologists can compute the age of a specimen by measuring the amounts of carbon 12 and carbon 14 present. The traditional method of measurement is accurate as far back as 50,000 years. A newer method that uses a device called a particle accelerator is accurate up to 60,000 years even with the tiniest specimens. Archaeologists use potassium-argon dating to find the age of certain rock formations in which archaeological objects are discovered. These rocks contain radioactive potassium 40, which changes into argon 40 gas at a constant rate. Scientists measure the amount of each element present and then calculate the age of the rock. This method was used to date rock formations found with bones and tools in eastern Africa. The rock was found to be 13/4 million years old, which indicated that the bones and tools were that age also.
The best-known method for dating wood is called dendrochronology. This technique involves counting the yearly growth rings visible on cross sections of cut trees. Archaeologists match the pattern of tree rings with those of ancient wooden objects to determine the age of the objects. Dendrochronology is the most accurate of all dating methods, but it can be used only with wooden objects up to about 8,000 years old.
Evaluation. Archaeologists evaluate artifacts and features to learn such information as how and where the objects were made and used. In some cases, the scientists learn by direct experimentation. In Central America, one archaeologist stored nuts for a year in underground chambers to support his theory that the Maya used the chambers to keep nuts. Artifacts and features can also help explain the social lives of ancient people. For example, the size of houses can show how many people lived in one household. The number and value of objects found in graves can indicate differences in social class. The evaluation of ecofacts reveals such information as what food people ate and whether they grew crops or gathered wild plants. Ecofacts can even explain ancient migration patterns. A seed of grain not native to the area where it is found may reveal how and when eating habits were carried from one place to another.
Archaeologists evaluate evidence with the help of specialists from other fields. Zoologists help identify animal bones and butchering techniques. Botanists analyze seeds to learn about ancient agricultural practices. Such specialists as geologists, architects, and engineers also work with archaeologists. In some cases, other specialists operate computers that greatly speed up the evaluation process.
History
Beginnings. The idea of studying the past through ancient objects has developed gradually. But the most intense interest has occurred in the past 200 years. During the 1700’s, some wealthy Europeans began to study and collect art objects from the times of ancient Greece and Rome. This interest in classical art is called antiquarianism. These first diggers looked only for treasures and threw away ordinary objects. Also during the 1700’s, European scholars began to debate how long human beings had lived on the earth. Their interest resulted partly from recent discoveries of primitive stone tools together with the bones of extinct animals. These scholars also knew about the huge mounds and ruined cities in the Americas that pointed to ancient human life there. They realized that human beings had a prehistoric past, but they could not decide when and where this past had begun.
The 1800’s brought a more scientific approach to the study of the past. The great length of human prehistory became widely accepted due to advances in geology and biology. By the early 1800’s, geologists had determined that rock formation resulted from extremely slow processes, such as erosion and volcanic activity. This view, known as uniformitarianism, led most scholars to believe that the earth was much older than previously thought. Then, in 1859, the British biologist Charles R. Darwin proposed the theory of biological evolution in his book The Origin of Species. This theory suggested that human beings, like other animals and the earth itself, had developed slowly over a great period of time.
By the mid-1800’s, archaeology had become a separate field of study, and evidence of human prehistory was accumulating rapidly. Important discoveries included prehistoric lake dwellings in Switzerland, ancient cave paintings in France and Spain, and part of a prehistoric human skull found in Germany. In the late 1800’s, archaeologists began to use techniques of excavation that made it possible to determine sequences of cultural development. In an excavation at Naqada, near Qus, Egypt, the British scholar Sir Flinders Petrie became one of the first diggers to look carefully for all remains, not just for treasures. Others who undertook major excavations at that time included the British nobleman Sir Austen Henry Layard, at Nineveh in what is now Iraq, and the German businessman Heinrich Schliemann, at Troy in what is now Turkey.
European archaeologists of the late 1800’s focused their studies on the ancient European and Middle Eastern civilizations described by classical and Biblical authors. American archaeologists, however, could find almost no written records of the civilizations they studied. Partly for this reason, they turned to anthropology for methods of interpreting their discoveries. For example, they studied artifacts produced by contemporary American Indians to help interpret objects from past societies. The 1900’s. The scope of archaeology expanded greatly during the 1900’s. Archaeologists began to explore the past civilizations of Central and South America, China, Japan, Southeast Asia, and other areas. By the early 1900’s, archaeologists were using stratigraphy and seriation to date their finds. During the mid-1900’s, new techniques made dating much easier and more accurate. The most significant of these techniques was radiocarbon dating, developed in the 1940’s by an American chemist named Willard F. Libby. Great advances in underwater archaeology also occurred during the mid-1900’s. Previously, underwater excavation had been both difficult and expensive. The aqualung and other diving devices invented during the 1940’s enabled divers to move more freely. Recent developments. Since the 1950’s, the primary aim of archaeologists has been to develop general theories that explain the changes in human societies revealed by archaeological evidence. For example, archaeologists today look for reasons behind the growth of cities in the Middle East about 3000 B.C.
Contemporary archaeologists have also developed many new research techniques. They use sampling methods based on the principles of statistics and probability. In this way, they can study sites quickly and without extensive excavation. New scientific methods also aid in the discovery of underground sites. For example, archaeologists can locate buried remains by using a magnetometer to measure slight irregularities in the earth’s magnetic field. This method led to the discovery of an ancient city buried 15 feet (4.6 meters) below the ground in Italy. A major concern among archaeologists today involves the preservation of archaeological sites that have not yet been studied. Many such sites are threatened by construction projects, the expansion of agriculture, and other types of development. The United States enacted laws during the 1960’s and 1970’s that require federal agencies to identify and preserve places that might be of historic importance.
On an international scale, archaeologists seek to halt the illegal sale of archaeological objects. They urge developed nations to enact and enforce laws to prohibit the import of ancient objects unless an export certificate has been obtained from the country of origin..