The J. Paul Getty Museum had an opportunity to obtain a kouros in the late 1980's.
A kouros is a type of Greek statue.
Only a dozen or so figures in good condition exist.
Experts analyzed the authenticity of the piece.
The question of whether the piece was a forgery has not been settled.
Archaeometry is the application of chemical and physical methods to the study of archaeological materials.
Archaeometrists study a wide variety of materials including marble, ceramics, bone, lithics, soils, dyes, and organic residues.
Work is typically done in wet-labs.
Archaeometry technically includes dating methods, remote sensing, and ancient DNA but these fields tend to pursue a separate identity.
Archaeological chemistry is part of archaeometry.
This involves the investigation of the inorganic and organic composition, elements and isotopes, molecules and compounds.
Organic compounds make up the tissues of living organisms and have the element carbon as a base.
Inorganic compounds do not normally contain carbon.
Archaeometry has a few primary concerns.
The first includes identification, determining the original material of an unknown item.
A second is authentication, verifying the antiquity of an item, often associated with works of art, archaeology.
The third is characterization, measuring the chemical composition of a variety of prehistoric materials.
One of the early and most famous examples involved the Piltdown discovery in England in the early part of the 20th Century.
A human skull and ape jaw were made to appear ancient and passed to experts as the "missing link" between apes and humans.
It took almost 40 years for new techniques to expose the deceit.
In the late 1940's, Fluorine Absorption confirmed the find was a forgery.
There were different levels of fluorine in the skull and jaw from Piltdown man.
Instrumentation
Archaeometry laboratories contain a wide range of instruments and equipment.
Several commonly used instruments measure the composition of various kinds of materials.
Each technique has advantages and disadvantages for different kinds of archaeological materials.
Important concerns in instrumental analysis are the condition of the sample, requirements for preparation, and whether the technique is destructive or non-destructive.
Neutron Activation Analysis (NAA)
Neutron activation analysis is an instrumental method for measuring elemental concentrations in a wide variety of samples.
Neutron activation determines many elements simultaneously.
Ceramics and various kinds of stone are common archaeological materials analyzed using NAA.
The method is destructive and samples are powdered for analysis.
About 70% of the elements have properties suitable for measurement by NAA.
Normally about 35 elements are measured quantitatively in 5 to 100 mg samples of archaeological and geological materials.
Facilities for NAA are somewhat limited in number and accessibility.
Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
ICP-MS is an efficient and general-purpose instrument for the analysis of a wide variety of materials.
ICP-MS is a standard technique for the measurement of trace elements.
The method is destructive, but almost anything that can be put into solution can be analyzed by ICP-MS.
A wide range of archaeological materials have been analyzed by ICP-MS including bone, ceramics, stone, metals, and glass.
The amount of most elements present in the original material can be measured in just minutes, even at low concentrations.
X-ray Diffraction (XRD)
X-ray diffraction is used to obtain structural and compositional information from crystalline materials.
XRD has been used largely for ceramics, rock, and sediment samples to identify the mineral constituents.
Gas Chromatography/Mass Spectrometry
The use of a gas chromatograph/mass spectrometry (GC/MS) instrument has become standard practice in the analysis of organic compounds.
Science in Archaeology: The Laboratory for Archaeological Chemistry
The Laboratory for Archaeological Chemistry at the University of Wisconsin-Madison was founded in 1987.
The lab is a center for research and training in the chemical analysis of archaeological materials.
There are only a few such facilities in the U.S.
The primary instruments in the lab are two inductively-coupled plasma (ICP) spectrometers.
The laboratory has two full-time staff members and employs several students as laboratory assistants.
The laboratory is also a center of training in archaeometric research.
Elemental Analyses
Elemental analysis is a major part of archaeometric research.
Such analysis is used for a variety of studies including authentication and characterization.
The elemental composition of archaeological items has been used for years as a tool to determine provenience.
Lithic Analysis
The geological sources of a variety of stone materials (lead, silver, obsidian, copper) have distinctive elemental signatures.
Finds of these materials at sites some distance from their sources provides a means for examining trade and interaction if the sources can be determined.
Example: Obsidian Sources and Trade in the Ancient Near East
In the past, obsidian was often traded or exchanged over long distances, hundreds of kilometers or more.
It is available from only a few sources.
Obsidian can be fingerprinted through minor differences in the chemical composition of the material.
Pieces can be traced to the places where they originated.
Neutron Activation Analysis (NAA) is commonly used in studies of obsidian.
Most of the obsidian in Southwest Asia comes from sources outside the Fertile Crescent.
Sites along Mediterranean coast generally obtained obsidian from Anatolia, while sites in the eastern part of the region used the Armenian material.
Ceramic Analysis
Ceramic analysis often involves elemental characterization to examine the composition and potential sources of raw material for the pottery.
NAA or ICP spectrometry is normally used for such analysis.
Information of interest includes manufacturing locations, trade and exchange, and more general economic patterns.
James Burton undertook an experiment using modern pottery from three Mexican villages.
Each village used different sources of clay for raw material and different recipes for their paste.
Potsherds were obtained from each village and analyzed by ICP spectrometer.
Results showed elemental differences between the different types of pottery.
Anthropogenic Sediments
Archaeological chemistry can be used for the analysis of anthropogenic sediments.
Different human activities in the past involved different kinds of materials.
The decomposition of those materials at archaeological sites should leave chemical traces in the sediments.
Soils from prehistoric occupations may contain information on site extent, boundaries, activities, chronology, resource availability or past environments.
Example: El Coyote
The site of El Coyote in northwestern Honduras was an important Classic Maya center between AD 600 and 1000.
There is a core of monumental buildings with 28 platforms and pyramids arranged around six plazas.
The main plaza is a flat, limestone-plastered surface roughly 100 by 50 m in size.
One of the unanswered questions about the large plazas at Maya sites concerns their use.
Excavations at El Coyote revealed large bowls and cooking jars, grinding stones for preparing corn, and a variety of flaked stone tools.
This was evidence of large-scale preparation and consumption of food and beverages.
Midden deposits outside the plaza contained evidence for craft manufacturing.
This suggests that the plaza was used for feasting and craft production, perhaps as a market area.
Soil chemistry was used to learn where activities took place on the plaza.
Three patterns of use in and around the large plaza were revealed.
Types of use included pigment preparation, ceremonial feasting, and domestic food preparation.
Isotopic Analysis
Isotopes are atoms of the same element that have different masses.
Isotopes of several elements are used in applications in archaeology other than dating.
Bone Chemistry and Prehistoric Diet
The primary use of isotopes in archaeology, outside of dating, has been in research on past diet.
Carbon and nitrogen isotopes from the food we eat are deposited in our tooth and bone.
People who eat certain tropical grasses like corn have higher ratios of carbon-13 isotopes in their bones.
Analysis of carbon isotopes from human bone from Mexico indicates that a heavy dependence on corn began sometime before 4000 B.C.
Carbon isotope ratios in the bones of human skeletons from the Mesolithic and Neolithic in Scandinavia and historic Greenland were measured.
The ratios from the Mesolithic are close to values for Eskimo skeletal material.
In the Neolithic, there was an increase in the importance of terrestrial foodstuffs among the early agriculturalists.
Nitrogen isotopes provide different information about diet.
The nitrogen system, in general, is less well understood than that of carbon isotopes.
Archaeological Thinking: Climate, Isotopes, and People
The Vikings, also known as the Norse people arrived in the Americas almost 500 years prior to Columbus.
Their voyage across the North Atlantic was made in a series of shorter trips.
Viking groups took domesticated cereals and animals with them and successfully cultivated these crops and fed their herds.
The Viking population of Greenland expanded to between 4000 and 5000 people after A.D. 900.
After A.D. 1300 their numbers began to decline.
By the middle of the 15th century Greenland was completely abandoned by the Norse.
There was a steady decline in the maximum temperature during the 500 years of occupation.
Isotopic studies of the tooth enamel from Norse burials from Greenland document these changes in climate.
Carbon isotopes in the enamel indicate a marked increase in the proportion of marine foods in the diet over time.
Archaeological evidence corroborates this scenario.
Human Provenience and Migration
One of the core questions in archaeology concerns changes in material culture.
Until recently archaeologists have not been able to determine directly if people themselves moved.
However, the application of isotopic tracers has made it possible to provenience human skeletons.
Migration can be determined by examining tooth enamel and skeletons.
Tooth enamel is composed of the things an individual ate during infancy.
The composition of bone is a product of the nutrients consumed during the last years of life.
Certain isotopes in the foods we eat are geographically distinctive.
If isotope ratios in tooth enamel and bone of an individual are different, that person must have changed residence.
Isotopic ratios are measured using a mass spectrometer.
Example: The First King of Copan
The site of Copan is located in Honduras, in the southwestern corner of the Maya region.
The central part of this huge site is dominated by an acropolis covered with temples, building, and inscribed stone stelae and altars.
This was the civic and ceremonial focus of the site and the residence and burial place of the rulers.
A series of graves and human burials around a large central tomb were found at the bottom of the earliest level of the acropolis.
The mound appears to have bee initially built to mark the burial place of one of the early rulers.
A number of inscriptions described Yax Kuk M'o, the first king of Copan.
He was said to have come to Copan from the north in AD 427 to found the dynasty at what was then a simple village.
This first king was also sometimes depicted wearing a costume typical of the major Mexican center of Teotihuacan, almost 750 miles away.
Bones and teeth from the central tomb and several of the adjacent graves were analyzed.
Isotopic analysis points to a place of birth to the north, but not Teotihuacan.
Other information suggests that the tomb was that of Yax Kuk M'o.
Organic Residues in Archaeology
Biological materials sometimes leave traces in and on artifacts and sediments which can survive for thousands of years.
Analysis of trace organic compounds can provide information about past artifact function, diet, and other aspects of prehistoric societies.
A variety of archaeological materials may contain trace organic compounds.
Lipids have been the focus of most investigations to date.
Lipids are a generic category of compounds that are constituents of living tissues.
Lipids appear to survive better than other organic compounds.
Although the analysis of trace organic compounds has great potential in archaeological research, a number of problems remain.
There are in fact a relatively small number of both reliable and useful studies that have been done to date.
Most of the effort, and success, in the organic analysis of archaeological residues has been in characterizing specific organic molecules retained in potsherds.
