by Michael G. Lamoureux, March/April 2009
Introduction
The introduction of radio-carbon dating and electron paramagnetic resonance in the 1940s and mass spectrometry, oxygen-isotope dating, and proton magnometers in the 1950s ushered in a golden age of technological advances over the next there decades that gave us virtually every tool and scientific technique that a modern archaeologist has at her disposal. With the introduction of thermoluminescence and potassium-argon dating in the 1960s, we are now able to date artifacts that are hundreds of thousands of years old. With the introduction of infrared data, satellite (LANDAT) data, and radar imaging techniques in the 1960s and 1970s, we are able to create precise land surveys from a distance (by way of remote sensing). With the introduction of computational archaeology in the same time-frame, we are now able to analyze huge data sets, perform detailed spatial analyses, and discover patterns and correlations that human eye might otherwise miss.
Similarly, the introduction of ethnological classification as part of anthropological, and thus archaeological, study by Franz Boas in the early 1900s, and the refinement of the idea by his students, and the introduction of modern scientific excavation and charting methodologies by Flinders Petrie in the 1920s and 1930s, paved the way for a golden age of archaeological theory that started with Leslie White's evolutionism in 1959 and Binford's "New Archaeology", which rose to prominence in the 1960s and advocated a scientific and multi-disciplinary approach, and ended with Hodder's "Post-Processual Archaeology" of the 1980s, which attempted to reinstate the use of psychological and symbolic factors of the non-material domains into Binford's more scientifically oriented "New Archaeology". Combined with the technological advances of the same time period, these theories still form the basis of archaeological study and pursuit twenty years later.
New Dating Techniques
The last fifty years saw the introduction of three important dating techniques, archaeomagnetic dating, thermoluminescence dating, and potassium-argon dating.
Archaeomagnetic dating, developed by Thellier and Thellier in 1959 and introduced to archaeology by Robert Dubois in the 1960s, is a technique that uses the magnetic direction of an artifact that contains iron oxide impurities to assign a highly accurate approximate date to an artifact. It's based on the fact that the direction of the earth's magnetic field changes over time and that this magnetic direction is captured at the time an object was last heated. Although the technique is geographically limited to areas of less than 1,000 kms in size, as the magnetic field fluctuates over the surface of the earth, and only gives accurate dates where archaeological magnetic curves have been calibrated, unlike radio-carbon, it gives an absolute date when the curves have been calibrated.
Thermoluminescence refers to the phosphorescence produced by the heating of a substance. The energy released is the energy stored by the substance from a previous exposure to ultraviolet and ionizing radiation. Thermoluminescence dating, developed by Grogler, Houterman, and Stauffer in 1960, uses the fact that the buried objects store an amount of thermoluminescent energy directly proportional to their age as the dose of ambient ionizing radiation received by a buried object (from radioactive elements in the soil, cosmic rays, etc.) is relatively constant on an annual basis. It is an important dating tool because the accuracy is on par with radio-carbon dating and it is able to give an absolute age estimate beyond radio-carbon calibration (which only extends roughly 10,000 years into the past).
Potassium-argon dating, introduced by Evernden & Curtis in 1965, which measures the products of the radioactive decay of potassium whose potassium-40 variant has a half-life of 1,260,000,000 years compared to 5,700 years for carbon-14, allows for the calculation of the absolute age of archaeological samples that are over 60,000 years old, which is the current limit to carbon-14 dating (according to the NOSAMS Radiocarbon Data and Calculations from the Woods Hole Oceanographic Institution in 2007).
A New Qualitative Field Test
In addition to new dating methods, the 1960s also saw the introduction of a qualitative field-test for the presence of phosphorous by Schwartz. Known as the Schwartz spot-test, this test, which involves the addition of two reagents of a soil sample placed on a filter paper, indicates the presence of phosphorous by way of the formation of a visible molybdenum blue stain whose intensity and extent correlates with the concentration of phosphorous in the sample. Furthermore, the solutions, which consist only of water, ammonium molybdate, nitric acid, and ascorbic acids, are easily mixed. This is important because phosphorous is unique among the elements in that it is a sensitive and persistent indicator of human activity. Concentrated in the soil by the addition of fecal matter (as modern humans excrete approximately 6g per year), bone, refuse, and other organic matter, it is a quick indication of past human occupation and the intensity, and even type, of human activity at the site.
Remote Sensing
The last fifty years also saw the introduction of a variety of remote sensing methodologies that allowed for the creation of detailed surveys that significantly surpassed the quality and depth of the surveys that could be produced using traditional aerial archaeology. These techniques included the introduction of satellite and infrared imaging, made possible with NASA's launch of the NIMBUS I in 1964; the introduction of full-spectrum imaging, made possible with the LANDSAT series of satellites, starting with LANDSAT I in 1972; and the introduction of radar, made possible with the launch of the SIR-A by NASA in 1981.
In 1968, Jean Pouquet published "Remote Direction of Terrain Features from NIMBUS I High Resolution Infrared" and effectively launched the field of remote sensing with infrared satellite archaeology. This paper, which discussed the isothermal mapping of Northern Africa, demonstrated the usefulness of geomorphology (the scientific study of landforms) and pedology (the study of soil). The ability to detect underwater rivers, for example, can give clues to the location of previous civilizations and extremely dry areas, which are known for their ability to preserve organic matter over long periods of time, may be more likely to conceal useful finds.
Following the launch of the NIMBUS I, in 1972, NASA launched the LANDSAT I which was the first in a series of seven earth imaging satellites (with the LANDSAT 7 launched in 1999) that collected agricultural, geological, hydrological, geographical, and other meteorological phenomena data using full electromagnetic spectrum imaging. This greatly extended the ability of the modern archaeologist to identify, map and survey potential archaeological sites as vegetation, water, soil, and rock contrast sharply in the rendered images. The importance cannot be overlooked as it helped archaeologists to locate the lost "Arabian Nights" city of Ubar in Southern Omen and greatly increased our knowledge of archaeological sites in Burgundy, France.
Shortly after the launch of the LANDSAT 3 in 1978, NASA launched the SIR-A (Spaceborne Imaging Radar A) imaging system in 1981 which used radar to improve our understanding of geologic features. This led to the use of air (and space) based radar for sub-surface artifact detection in the mid-1980s which allowed archaeologists to map large sites covered by jungle or desert, such as those found in the Yucatan or African deserts. About the same time, ground penetrating radar, developed for military purposes in the 1970s, was also deployed as an archaeological tool. This has allowed for the identification of buried kivas (semi-subterranean structures used for habitation) in the American Southwest, buried structures at the "Treasury" in Petra, Jordan and unmarked graves in cemeteries, among other finds.
Computational Archaeology
In addition to the introduction of new dating methodologies and an array of remote sensing technologies, the last fifty years also saw the introduction of computational archaeology. Computational archaeology, which allows for the processing of large data sets, including LANDSAT data, has enabled significant advances in typology, spatial analysis, and site reconstruction and interpretation. Computational archaeology, which emerged as its own sub-discipline with the publication of "Systems Theory, Computer Simulations, and Archaeology" and "Archaeological Reasoning and Machine Reasoning" by J. E. Doran in 1970, uses computers to perform extensive statistical, spatial, and inference analysis on large volumes of data and mine for patterns.
Typology
Typology, the classification of things according to their characteristics, helps an archaeologist manage large masses of archaeological data, but the "superficially straightforward task has proved one of the most time consuming and contentious aspects of archaeological research" according to Doran and Hodson in their early text on "Mathematics and Computers in Archaeology", published in 1975. However, the introduction of the computer, which could quickly do (cluster, principal component, correspondence, and factor) analyses across large data sets, changed all that. For example, it allowed Roger Grace, who developed an expert system called LITHAN (LITHic ANalysis of stone tools) for the classification and typology of tools in 1989, to automatically classify the remains of early stone tools through observed metric and non-metric attributes entered as pre-defined data elements into the program.
Spatial Analysis
Spatial analysis, which is the study of an archaeological site using the topological, geometric, and geographic properties of the site, is also advanced in the computational context. Computers allow for the quick and accurate calculation of autocorrelation measures, regressions (which capture spatial dependency), interactions (via "gravity models"), and even interpolation (which can estimate missing data). It allows archaeologists to reconstruct the growth of urban systems, construct chronologies, and even infer intra-room activity in a household. For example, urban centers tend to build outward from a center (that a spatial analysis can identify), similar ceramic styles will "cluster" together in time (and give us ceramic chronologies), and the spatial analysis of micro-refuse recently brought to light the intra-room activity at the small Late Neolithic farmstead of Tabaqat al-Buma in northern Jordan, as described by Ullah earlier this year.
Methodological Advances
However, as indicated, the advances of the last fifty years were not limited solely to technology. A number of methodological advances, including evolutionism, techniques for non-destructive site entry, ceramic sociology, numerical taxonomy, and locational analysis were introduced and the last fifty years saw the introduction of two new schools of archeological thought. In the 1960s, under the leadership of Binford, we were introduced to the "New Archaeology" which was a conscientious effort to make the discipline multidisciplinary and more "scientific", and then in 1980s we were introduced to Hodder's "Post-Processual Archaeology" that tried to integrate a psychological approach with the scientific approach of Binford.
In 1959, Leslie White published "The Evolution of Culture: The Development of Civilization to the Fall of Rome" that rekindled interest in the concept of social evolutionism and presented a materialist approach to the subject. White argued that among the three components of culture -- technological, sociological, and ideological, the technological component was the primary factor responsible for cultural evolution because "man as an animal species, and consequently culture as a whole, is dependent upon the material, mechanical means of adjustment to the natural environment".
In 1962, Constance Cronin devised the theory of ceramic sociology which postulated that there were uniformities in design that were associated with a specific site over time. This idea contrasted sharply with the prevailing ideology of the time that postulated that ceramic designs changed uniformly with the passage of time. Based on her studies of prehistoric ceramics from a variety of sites in Arizona, she was able to deduce that there were ceramic traditions that were localized and passed on within single sites. This was an important theoretical development as it allows social anthropologists to determine the extent of intra-societal and inter-societal exchange in any culture where one or more ceramic traditions can be localized.
In 1963, with the publication of "Principles of Numerical Taxonomy", Robert Sokal & Peter Sneath introduced numerical taxonomy, which was a result of research that began in 1959 at the University of Kansas. Numerical taxonomy creates taxonomic classifications by way of numeric algorithms (such as cluster analysis). Applications include the automatic typology of (paleo and neo)lithic stone tools, ceramics, and early bronze and iron age tools.
Locational analysis, which is the foundation for modern spatial analysis, is the search for additional information from the geological placement and spacing of sites, was introduced in the mid-1960s with Peter Hagget's "Locational Analysis in Human Geography" and cemented as an archaeological technique by Ian Hodder and Clive Orton in 1976 with their publication of "Spatial Analysis in Archaeology". The contributions of the early work are far reaching and have helped scholars determine the variations between Pleistocene sites in East Africa, identify the number of Dvaravati Kingdoms in Central Thailand, and explain the social logic of Teotihuacan domestic spaces.
In 1960, Fondazione Lerici developed a method of non-destructive entry where he used a periscope that he drove through the roof of Etruscan tombs to photograph the interior. Non-destructive entry is an important archaeological technique as it preserves a delicate site, which could easily be destroyed by traditional archaeological excavations, for study by future generations of archaeologists.
The "New Archaeology"
Under the leadership of Lewis Binford, the "New Archaeology" emerged in the 1960s. The core tenants of the New Archaeology, which Binford argued needed to be more "scientific" and multidisciplinary, was that archaeology needed to be explicitly scientific, demand social relevance, and reject established arguments based on authority alone (and not fact). These foundations eventually led to the prevailing view (at the time) that culture is a series of inter-related sub-systems, that ecological relationships cannot be ignored, and that modern tools, including statistics, computational archaeology, and (non-destructive) remote sensing needed to be a standard part of every archaeologist's toolkit.
The "Post Processual Archaeology"
The "New Archaeology" flourished for two decades until Ian Hodder converted some of its followers, along with schools of upcoming archaeologists, to the "Post Processual Archaeology" that he introduced with his publications on "Symbols in Action. Ethnoarchaeological studies of material culture" and "The Present Past. An introduction to anthropology for archaeologists" in 1982. Hodder believed that the rejection of psychological and symbolic factors by the scientifically-oriented new archaeologists did not do justice to the archaeological record as he believed that non-material domains were crucial to deciphering past cultures. In the post-processualism he introduced, archaeologists attempted to integrate a wide-range of social anthropology practices in cultural reconstruction into their scientifically oriented new archaeology toolkit, including critical theory, world systems, religious, and gender studies. Whereas the tenets of the "New Archaeology" promoted the scientific, the tenets of the post-processual archaeology called for a reflexive archaeology where archaeologists were concerned with how personal archaeological style affected their conclusions, insisted that the archaeological object be considered in the context of its ancient meaning, and emphasized that the very requirement for a dialogue between the archaeologist and the archaeological record prevents a truly objective interpretation of the past. Post-Processualism, along with key tenets of the New Archaeology, remain prominent in the archaeological world to this day.
Summary
In conclusion, the last fifty years, and the 1960s, 1970s, and 1980s in particular, were a golden age in modern archaeology that saw the introduction of a wide-range of useful dating, remote sensing, and analytical technologies as well as an influential range of analytical methodologies that included evolutionism, non-destructive entry, ceramic sociology, numerical taxonomy, and locational analysis. This led to the development of the "New Archaeology" in the 1960s, the "Post-Processual Archaeology" in the 1980s, and ultimately to modern archaeology which blends the New Archaeology teachings of Binford with the post-processual considerations of Hodder to give us an expansive and insightful view into what archaeology is, and will be.