Archaeology is the study of human cultures of the past through their material culture. Material Culture includes: Artifacts (any object that was intentionally modified by a human); Ecofacts (an object that is usually associated with economy and diet such as the discarded bones of animals after butchering); Cultural Features (areas within archaeological sites that are usually associated with specific types of activities); and, Sites (the structured clusters of artifacts, ecofacts, and cultural features.
What are Archaeological Data?
When archaeologists discover archaeological sites, excavate cultural
features and collect artifacts and ecofacts, they begin the process of
transforming the archaeological record into data. The material that
archaeologists
find at archaeological sites are not data, they are simply objects.
Archaeologists transform artifacts and other objects recovered into
data by recording their attributes (measuring, weighing them, figuring
out their chemical composition, etc.).
The Dimensions of the Archaeological Record include Space, Time, and Form. Each of these three dimensions forms a basic aspect of archaeological inquiry.
A. SPACE
Space refers to the area of an archaeological site. The ways in which
sites spatially occur can be used to reconstruct the daily activities,
social relations, economy, etc..of the inhabitants of the
site.
Methods of Locating an Archaeological Site
Locating archaeological sites is a lot like detective work, with a
little bit of statistics and luck thrown in for good measure. The
easiest
way to find a site is to ask someone who knows where one is.
Notwithstanding
good fortune and knowledgeable local informants, archaeologists know
that
people almost always had excellent reasons for living and working where
they did. As such, archaeological sites seldom occur in random
locations.
Areas that are elevated, well drained, and have good access to water and resources today were occasionally also good places for people to have lived in the past. The situation is more complicated when environmental conditions change over time. In these circumstances, places that were excellent locations to live in the past, may not as such in the present. As a result, our methods of detecting archaeological sites must become more sophisticated.
Aerial Photography
The origins of aerial photography in archaeology dates back to the
1930s when Charles Lindbergh collaborated with the famous southwestern
archaeologist A.V. Kidder to photograph some of the more spectacular
pueblo
ruins in this region.
Notwithstanding some rare examples, few archaeological sites remain visible on the surface. More often, land use, development and natural processes result in sites being buried. Buried sites, under certain circumstances can still be seen using aerial photography. Buried features under the soil often appear as Crop Marks. Crop marks are made visible due to the varying amount of moisture over top and between buried features.
More sophisticated method of identifying sites is from space. Satellite images have, for example, aided paleoanthropologists in their quest to discover hominid fossils in the Great Rift Valley in Ethiopia. Here, the Landsat data was used to identify fault and drainage features that might yield hominid fossils
Subsurface Testing
More down-to-earth techniques for finding sites include: Proton
Magnetometry,
Soil Resistivity, Ground Penetrating Radar and Shovel Testing.
Proton Magnetometry measures magnetic anomalies in the earth's magnetic field caused by buried artifacts or cultural features. When clay containing iron particles is fired, the alignment of the particles become re-oriented. Since the location of the magnetic north pole has changed through time, clays that were fired in the past produce orientations that are anomalous with those of today. Such anomalies can be detected and plotted as a contour map indicating the location of archaeological materials. Magnetometer surveys are, however, influenced by a variety of factors, including electrical storms, the presence of iron fences, and nearby electrical wires.
Soil Resistivity is conducted by inserting a series of probes into the ground at regular intervals (e.g. +/- 5m) along a transect. An electrical current is then passed through the ground via the probes. Archaeological features such as house floors and walls are often denser than the surrounding soil. As a result, they contain less water and cause electrical resistance when current passes through them. When this resistance is measured, it can be plotted as a graph. Unfortunately, the presence of groundwater can impact on the results.
Ground Penetrating Radar sends radar pulses into the earth that are reflected back by anything that is buried. As the pulses are reflected back, their speed to the target and the nature of their return are measured. The reflection time of the signal can provide information on the depth and shape of buried objects. Again, groundwater can affect GPR results because it changes the permeability of the surrounding soils. GPR is also ineffective over clays, saltwater, and at depths of more than 30 ft below the surface.
Shovel Testing, Surveys and Probability Sampling are also used to decide where to dig. In areas where sites are known to exist, their locations can be used to develop predictive models to locate other sites. Where there is little or no information about an area, random sampling might be used to determine an area's potential. Testing for sites can be done through the excavation of test pits, trenches and borings.
Site Excavation
In choosing an area within the site to excavate, archaeologists
must determine what the specific research goals are. It is important to
note that it is often impractical and unethical to excavate an entire
site,
since archaeology is a destructive process. Most archaeologists leave
areas
of sites unexcavated for future archaeologists with more advanced field
methods to work on.
Artifacts Densities recorded during surveys are often used to assist the archaeologist in deciding where to excavate. Areas with high artifact densities, for example, are often excellent places to start.
When an artifact, ecofact, or cultural feature is encountered, the horizontal and vertical provenience is then recorded. Horizontal Provenience is the spatial position of the object relative to a fixed point on the site. This fixed point is referred to as the site datum. Vertical Provenience is the position of the object within the stratigraphy of the site. Vertical provenience provides archaeologists with information relating to the temporal position of the object.
The Law of Superposition states that an object's position within a stratigraphic profile will determine its age relative to other objects found above and below it. Taken together, this information allows us to identify activities based on associations between artifacts and the place those activities in time.
B. TIME
Organizing artifacts, cultural features, and archaeological sites in
time is an important aspect of archaeological inquiry. Archaeologists
do
this by making the distinction between relative and absolute dating
techniques.
Relative Dating Techniques date materials relative to other materials. One way to relatively date artifacts is through their vertical association. Another way is to assess artifact style. In this regard, the characteristics of some artifacts are what we call "time sensitive". Archaeologists recognize that the shapes, raw materials, manufacturing techniques, and types of decoration on certain artifacts change over time. Knowing this, archaeologists can use a technique known as Seriation to chart stylistic trends through time.
Absolute Dating Techniques are usually borrowed from the physical sciences and provide archaeologists with an actual calender date for an object. The most widely used of these techniques is radiocarbon dating which is based on the production of cosmic radiation that produces neutrons that interact with nitrogen to produce C14 a carbon isotope that is unstable. The unstable nucleus of the C14 isotope is subject to radioactive decay, and in 5730 years, ½ of a C14 sample will decay away. Because plants and animals ingest atmospheric carbon until the time they die, you can measure the amount of C14 still present in a dead organism and then estimate how long ago that organism died from the known ratios.
Natural variations in the concentration of C14 in atmosphere and the fact that C14 does not mix evenly in all environments, especially in the earth's oceans, makes dating more complicated. Researchers now "correct" for these inconsistencies with the creation of a calibration curve in which tree ring dates were used to correct radiocarbon dates.
Other absolute dating techniques include: Potassium/Argon - a radiometric technique used to date volcanic rock. There is virtually no upper limit to this technique, but it is only feasible on rock at least 10,000 years old. Obsidian Hydration - used for dating obsidian (volcanic glass) tools (800,000 BP to present) - based on the build up of a hydration layer caused by chemical reaction of obsidian with water. Thermoluminescence Dating - used for dating fired clay in pots (practically no limits) - measures the amount of energy in the decay of radioactive elements in surrounding soil. Dendrochronology - used for dating wooden objects (limit is the oldest tree) - tree ring counting. Fission Track Dating (on volcanic rock) which examines microscopic damage due to radioactive decay (1,000,00 to 100,000 years BP).
Seasonality Studies
Another aspect of time considered important in archaeological sites
is that of seasonality. This is the determination of the season or
seasons
in which sites were occupied. Seasonality is most directly
determined
using ecofacts, the remains of plants and animals that are recovered
from
archaeological sites. The age of an animal at the time of its death can
be useful in determining when a site was occupied. The age of an animal
can be determined in a number of ways, including: the examination of
the
state of the epiphyses on long bones (fusion); annual growth bands in
teeth;
and, the presence or absence of seasonally specific features like
antler.
Site Formation and Transformation
Time is an important element in the formation of archaeological
sites. If the spatial associations of artifacts are reflections of the
behaviors that produced them, then it is important to understand how
artifacts
and ecofacts can be added to; subtracted from; and moved around in the
archaeological record. Michael Schiffer identified four
specific
types of site formation processes that can blur the archaeological
record.
These are:
1. Deposition - the discard of artifacts, ecofacts, and human remains in specific spatial locations, as well as in a casual, opportunistic manner. The use of middens and cemeteries, for example, constitute purposeful deposition in a spatially specific location. The deposition of objects in middens is usually conditioned by the size of the objects in question.
2. Reclamation - artifacts that are deposited in archaeological contexts are sometimes discovered by other individuals and subsequently re-used and re-deposited.
3. Disturbance - disturbance processes can be both natural and cultural, and they usually result in the alternation of the vertical and/or horizontal provenience of the artifact or ecofact. Disturbance processes can also remove artifacts from the archaeological record by destroying or transporting them.
4. Re-use Processes - at first, reuse seems similar to reclamation. However, these two processes are different from one another, because reuse involves an object being used in a variety of different ways within the same context.
Middle Range Theory
One of the ways in which archaeologists control for site formation
processes is through the use of Middle Range Theory. Middle Range
Theory
was developed by Processual Archaeologists such to link the
static
archaeological record to the behavior that produced it. This is
accomplished
is through the use of bridging arguments that use observations of site
formation processes at work in the present to identify their presence
at
archaeological sites in the past. One way of developing bridging
arguments
is through the practice of ethnoarchaeology. Ethnoarchaeology
requires
the archaeologist to observe how the archaeological record forms. This
is done by living as an anthropologist in a contemporary society and
observing
how people manipulate the physical environment (e.g. how they make
pots,
where they discard the refuse, how they use their house, etc.).
C. FORM
Most artifacts have a form, i.e., a distinctive shape, size, color,
or design. When artifacts share similar combinations of such
attributes,
they are often grouped together into types. Types are used by
archaeologists
to denote specific time periods, as well as define ethnic groups. Two
specific
“types” of types are morphological types and temporal
types.
Morphological Types represents an initial stage of archaeological classification and chronology building. The emphasis is on grouping artifacts into broad, abstract categories based on the subjective analysis of attributes. When artifacts share enough of attributes, they are said to be part of the same group. An Attribute is an individual characteristic that distinguishes one artifact from another on the basis of its size, surface texture, form, material, method of manufacture, and design pattern.
Temporal Types are used as time markers. Temporal types are extremely useful to archaeologists because, once they are defined, they can then be used to date archaeological sites in other regions where they occur.
Areas of Research Focus in Archaeology and Physical
Anthropology
Archaeological and Physical Anthropological Research has many areas
of specialization.
Some of these include:
Experimental Archaeology
In experimental archaeology, technological procedures we think were
used in the past are tested under controlled laboratory conditions in
the
present. Experiments such as use wear studies, which indicate
diagnostic
forms of edge damage and polish on stone tools are good examples of
Experimental
Archaeology
Reconstructing Diet and Subsistence
Archaeologists can reconstruct diet and subsistence by assessing the
plant and animal remains recovered from archaeological sites. Plant
remains
such as phytoliths are often used to identify the presence of
plants
that may not have survived in the archaeological record. Phytoliths are
small silica bodies which form in certain types of plants. Zooarchaeology
is another way in which diet and subsistence can be studied. Animal
species
present at archaeological sites are identified and then ranked
according
to their economic importance. One way this is done is by quantifying
taxonomic
abundance. Two common measures of taxonomic abundance are MNI (Minimum
Number of Individuals) and NISP (Number of Individual
Specimens).
Meat yield estimates are also used in coordination with NISP and MNI,
and
provide a more accurate picture of economic importance.
Reconstructing Mobility Strategies and Site Patterns
Another avenue of archaeological research is the reconstruction of
mobility patterns. Human societies of the past ranged along a continuum
from highly mobile (hunter gatherers) to sedentary (state level
societies).
Archaeological research has shown us that hunter gatherers move about a
great deal with great care and planning, making sure that they are
there
able to take advantage of seasonally available resources. Among more
complex
sedentary societies, we often find that large sites are surrounded by
smaller
sites that service them. Such intersite patterns are often referred to
as settlement hierarchies, and denote power relations between sites and
their residents.
Reconstructing Social Organization
Social Organization is often determined by economy and population
density.
Archaeologists who estimate population density can reconstruct the age,
sex, and number of people in a society using a number of techniques.
These
include the study of mortuary remains; artifact densities; the carrying
capacity of the site catchment area; the floor area of dwellings, and
the
size of sites. Forms of social organization can be categorized as: Bands
and
Tribes are more or less egalitarian, with no one
individual
having any real power over another. Chiefdoms and States
are more complex, with individuals occupying high status positions over
others that are ascribed at birth. Eventually, states become so
internally
differentiated that they stop functioning efficiently and eventually
collapse.
In the archaeological record, status indicators cross cutting age and
sex
lines are often attributed to ascribed status, suggesting
socio-political
complexity above the level of Band or Tribe.
Reconstructing Ideology
Ideology or people's thoughts are not something that comes easy to
archaeology, since archaeologists primarily deal with material culture.
However, ideology is accessible, at least to some extent, just as
social
systems are. Representations of ideology can be found in burial
methods,
grave items and death assemblages.
Osteology
The study of human remains are of interest to archaeologists and
physical
anthropologists because they can provided a wealth of knowledge
relating
to evolution, trauma, stress, adaptation, disease, lifestyle, ideology,
social organization, economy, etc.. Basic forensic techniques include
the
identification of sex, age, health and cause of death. More recently,
dietary
studies are made possible through bone chemistry studies. DNA analyses
are being used to test the relatedness of individuals and populations.
Some Ethical Concerns Regarding the Study of Human Remains
The excavation of human remains is a very serious concern these days.
It has been argued that one special interest group should not have
control
over science and that important information will be lost if we do not
allow
the study of human remains. Alternatively, it has been proposed the
beliefs
and wishes of the descendant populations should be recognized. In North
America today, permission is rare, to knowingly excavate human remains
for study. In cases where excavations do take place, usually because
the
grave is in danger of destruction, the remains are often now returned
for
reburial (although physical anthropologists do sometimes get a chance
to
study the remains for a period of time). The Kennewick
Man is a very recent case that has ended up in the courts and
has
attracted worldwide attention.
At present, there are many collections of human remains around the world that are presently being sought after by various First Nations groups for reburial. In the United States NAGPRA legislation (North American Graves Protection and Reburial Act) has been enacted to facilitate this process. As yet, there is no such federal legislation in Canada, individual Provinces have various policies regarding this issue. The repatriation of human remains is not re-burial, rather it refers to the control of the remains. Reburial is often a consequence of repatriation, but repatriation does not automatically mean that the remains will be reburied.