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Introduction
As a subdiscipline of archaeology, the merits of zooarchaeology as recognized today were, unfortunately not realized until late in the progression of archaeology as a study. In modern excavation and interpretation , however, the study of animal remains, termed zooarchaeology or archaezoology has become increasingly prominent and now lends integral information to the formulation of dependable theories by archaeologists all over the world. Where historically, zooarchaeology was employed for very limited and broad climatic indication and dating, post World War II archaeology depends upon the growing field of zooarchaeology for a wide range of precise investigations (Thomas 1996). It can be seen that techniques in faunal dating using animal remains such as bones have experienced tremendous refinement since the first excavations, resulting in their more widespread utilization. Furthermore, among the many areas of study of the human past illuminated by zooarchaeology, there are two of particular importance; the reconstruction of ancient subsistence and exploitation of natural resources and the quantitative and qualitative evaluation of ancient environmental conditions. Together with advances in absolute dating, excavation methods and knowledge in the evolution of organisms, the study of macro- and microscopic animal remains, have allowed zooarchaeologists and archaeologists to collaboratively begin to answer many challenging questions that would have seemed almost unfeasible by their predecessors in the field.
Classification and handling of zooarchaeological materials
The enormous range of size and diversity in the living and fossilized species represented on earth reflects the need for the distinction of two types of fauna examined by zooarchaeologists. The first type, called the microfauna include the morphologically smaller organisms such as insects, molluscs and in some cases, even microscopic protists. The benefits provided by the remains of these animals can be realized through the tedious tasks of screening or the use of flotation techniques at an archaeological site (Amorosi et al 1996) or by the examination of rock layers for the fossilized remains of micro-organisms. While the costs of microfaunal recovery can be substantial with respect to time and effort, the advantages of such recovery are numerous, and often provide evidence with greater precision than macrofaunal remains. Due to the fact that smaller organisms are found in greater numbers, bias of interpretation is less common in that statistical significance of their analysis is generally better (Bahn and Renfrew 1996). Furthermore, since smaller organisms have been observed to be much more sensitive climatic change, they are often far superior indicators of ancient local and regional environmental fluctuation within a narrow margin of change.
Encompassed in the study and interpretation of macrofauna are the larger animals, including those commonly domesticated and exploited by ancient peoples such as horses, pigs, and cows as well as long extinct species that roamed the early earth, such as mammoths. When employed by zooarchaeologists as environmental indicators, macrofauna are much less reliable than microfauna because of their higher resistance and adaptability to changes in the environment (Bahn and Renfrew 1996). However, where the study of ancient human subsistence is involved, advantageous inference from macrofaunal remains occurs often because of the favorable preservation conditions of their remains associated with animal domestication and exploitation (Lyman 1987). Studies in taphonomy, (or burial and deposition of animal remains after death) have shown some human behaviors such as animal remain burial which favour their preservation and depict their use by the culture (Lyman 1987). Particularly for macrofaunal remains, upon recovery of such assemblages at a site, it is important that the zooarchaeologist determine the means of accumulation of those remains at the site, in order to correctly relate their association to the people being investigated (Lupo and Schmitt 1995). When a zooarchaeologist recovers well-preserved animal bones and can distinguish between those placed in an area from natural causes or human deposition, he may begin to exercise their importance with respect to chronology, subsistence, environmental indication, or any combination of these topics.
Reconstruction of ancient subsistence and animal exploitation
Subsistence in archaeological interpretations is generally referred to as that which is necessary for human survival, with the main focus on food, but also incorporating factors such as fuel and clothing ( Bahn and Renfrew 1996). In documenting ancient subsistence, zooarchaeologists play an essential role in the recovery and elucidation of macrofaunal remains as representatives of ancient human activity with regards to the processes of food preparation. As previously mentioned, once a set of animal remains are found at a site, it is essential that the means by which the remains accumulated in the area are determined. Since, in ancient times, wild animals usually fell victim to human predation less than predation by other animals or by natural causes, when animal remains are recovered, proof of human exploitation of faunal remains is indispensable to the accurate reconstruction of subsistence. There are several ways through which such contextual proof can be established. Currently, workers in the field of experimental archaeology strive to re-enact possible handling and butchering practices of ancient peoples. Through the delineation of the types of cut and scratch marks left on animal bone, for example, archaeologists can begin to distinguish features left in animal bone by tools used by humans to manipulate the animal from traces of left by other animals or the environment (Luff 1984). Experimentation is also useful in cases where modification of faunal components such as antlers are inferred to have been used as tools or for purposes other than diet.
Since macrofaunal remains have proven to be the most available and beneficial indicators of ancient subsistence, a systematic approach has been adopted by archaeologists in order to extract as much information as possible. The first step in the analysis of any set of faunal remain is their qualitative assessment, meaning their identification as representative of a certain species (Grayson 1984). Next, a series of statistical calculations must be made in order to show the numbers of animals and amount of meat portrayed as well as sex and age ranges of preserved fauna at the site (Grayson 1984). Once this is determined, a significant amount of information can be deduced with regards to exploitation of the animals, even before closer examination of the recovered materials themselves for evidence of processing. This can be illustrated in the case of zooarchaeological investigation of the Garnsey bison bonebed, an example of animal exploitation in new Mexico which has provided information on ancient hunting practices. Statistical analysis of the remains at the site showed more male skulls than female, but more female limbs than male (Speth 1983). It was further concluded that, since the bison were hunted in the spring, when the female cows would be weaker and less nourished as a result of lactation and calving, the male bison were selected for over the females for their larger quantities of meat, and were hence, removed from the site for further processing (Speth 1984).
Where the evaluation of ancient animal domestication is concerned, zooarchaeology lends important information leading to conclusive evidence on the status of animal remains as being either wild or domestic. Trends in morphology of certain components of animals, such as reduced jawbone size and spacing between teeth in dogs (Luff 1984) can represent domestication of species and lead to classification of ancient peoples as hunter/gatherers or more sedentary villagers.
Although the examination of slight morphological change over time has provided extensive information, determining domestication soley on this basis is often quite difficult, as such change is often difficult to detect and prove (Luff 1984). Where age of remains are not clearly defined, it would be difficult to distinguish a seemingly mutated version of an animal from one in its developmental stages, if slightly different in morphology from the adult form. Furthermore, it is often difficult to isolate gradual adaptation leading to morphological changes strictly in response to domestication since changes, such as decrease in body size have occured independently over many species since the last Ice Age. Nonetheless, where zooarchaeology continues to thrive in the determination of domestication is in the technique of bone microstructure analysis. It has been scientifically proven that the domestication of animals produces livestock with decreased bone resilience as a result of any or a combination of factors including poor nutrition, lack of exercise and diminished genetic variation (Drew et al 1971). When the underlying structure of bone is examined under a microscope, the conformation of tiny bone components can accurately identify the animal as wild or domestic. This technique can be seen as advantageous to archaeological interpretation of ancient subsistence, not only because of its renown accuracy, but also due to the fact that only small samples are needed to produce conclusive evidence of domestication.
In the mapping of ancient subsistence, microfauna are less commonly employed, not only because they become deposited at sites from their own burrowing activities (Olsen 1971), but also due to the fact that they are not as widely domesticated for subsistence purposes. Nonetheless, there are several cases where the study of microfaunal assemblages have had significant influence on the reconstruction of ancient diet, such as through the investigation of molluscs in shell middens. The investigation of such refuse pits has been successful not only because it has been relatively easy to determine that their deposition was the result of human activity, but also because of the superior preservation of mollusc shells as opposed to animal bone. It is due to the latter phenomenon, however that particular caution must be taken in the archaeological interpretation of ancient diets. As a result of their much better preservation, molluscs have far surpassed other remains in the fossil record and, subsequently have often been falsely labeled a main staple of many diets (Bahn and Renfrew 1996). However, with careful calculations of meat and caloric contribution, their roles in sustaining ancient populations have been assessed.
Delineation of past environment and climatic change
In archaeological interpretation, the determination of past environmental conditions has played a crucial role in learning how and where people lived as methods of survival and adaptation to external factors. As reliable indicators of local and regional conditions, faunal remains have been instrumental in this process, microfauna being of particular importance. Being extremely numerous and sensitive to slight short or long-term environmental fluctuation, small organisms such as insects, birds and rodents adapt quickly and subsequently explicitly illustrate the types of environments ancient people endured (Luff 1984). Characteristics of climate indicated by genetic and morphological differences in organisms over time include expansive global factors, such as glacial conditions as contemporaneous with the different global phases or more finely tuned environmental conditions such as rainfall and temperature. When a set of faunal remains are recovered at a site, as with faunal remains used in subsistence reconstruction, identification of means of aggregation prior to use in environmental indication is necessary. As the determination of climate from faunal remains usually aims to relate conditions expressed through the fauna to an entire archaeological layer (Amorosi et al 1996), it is crucial that the faunal remains be proven contemporaneous with the layer itself and not the result of animal burrowing. For the examination of smaller-scale climate, determination of the context of the animal remains is also important, since faunal remains would not accurately reflect local climate if found in their secondary context.
Apart from being an excellent source of direct evidence of ancient subsistence as previously discussed, the expansive layers of shell refuse collected in shell middens over long or short periods of time have been invaluable means of population and environmental indication. Combined with their favorable chemical composition allowing for optimal preservation, the human activity of piling large amounts of shells on top of one another in succession can be seen as a readily available, compact history of seasonal and climatic change. Specifically, changing relative frequencies of certain species of marine molluscs that are more capable of sustaining certain conditions over periods of time indicate alterations in environment (Evans 1969). If, for example, the frequency of a certain bivalve which responds well to sandy as opposed to rocky surroundings is high, one could deduce that the environment from which the marine mollusc was harvested to have been sandy. Through inference of temperature from other relative frequencies in the midden, the combined factors begin to illustrate immediate environmental conditions, and if the location of harvest can be determined as within the region of occupied by the people, a fairly accurate estimation of their surroundings will have been accomplished.
Although the depiction of ancient ecological setting relies chiefly on fossilized microfauna, there are rare cases in which exceptional preservation of intact macrofaunal bodies have been recovered replete with clues to the conditions in which they lived (Luff 1984). In cases where tissues such as skin and fur are found intact due to extremes of temperature or moisture where such components usually decay rather quickly without leaving a trace, careful analysis often leads to significant detailed descriptions of environment. In certain cases, such as the phenomenal finding of the extremely well-preserved mammoths in the Siberian permafrost (Pfizenmayer 1939), molecular biological testing using DNA can produce astonishing results with respect to animal diet and genetic expression as a result of environmental factors. Furthermore, where extinctions of large wild animals, such as the woolly rhinoceros are considered, broad conclusions of climate can be drawn where remains of such species are found as to the factors which drove such animals to extinction.
Dating
When well-preserved and proven to be in primary context, macro- and microfaunal remains are commonly used in relative dating techniques to establish chronology at archaeological sites. With an in-depth knowledge of animal evolution, archaeologists can cross-date artefacts with fossils found in the same context as a site and achieve reliable results. Given that the process of evolution is an ongoing mechanism of survival for species that gives rise to modified forms of organisms via genetic mutation over time, immense variance in morphology of animals over time plays an integral role in archaeological cross-dating (Michels 1981). Since animal evolution has been carefully mapped in many species, presence of an early or late variety of an organism found to be in association with other archaeological remains can provide a broad estimated date that corresponds to a particular period in evolutionary history. Perhaps of greater benefit to the chronology of the remains, if genetic material is accessible in the form of DNA and the fossilized organism is known to be the ancestor of a present day organism, a very precise measurement of the date at which the fossil would have been alive can be established. The process of mitochondrial DNA comparison of the two organisms for the determination of amount of variance between molecular structure acts as a �clock� that presents an accurate account of the time since the two organisms diverged (Carefoot et al 1998). As the downfall of this method in dating however, there are some variations of organisms that, as a result of their evolutionary success, have lasted over several long periods in the history of organisms. This fact is demonstrated in the fact that there are several modern day organisms which bear little modification from ancestral forms. In such cases, only a very broad date can be assigned to artefacts or archaeological remains (Michels 1981).
Further to cross dating using genetic divergence clocks to separate a fossil and associated remains from present day, the use of index fossils found in relation to geomorphic events of the Pleistocene epoch, such as glaciation has provided another reliable method in chronology of this epoch (Michels 1981). Since the Pleistocene epoch is characterized by many successive geomorphological events such as widespread freezing or cooling, significant geological evidence in the form of erosion mark warm and cool periods (Michels 1981). Many European Pleistocene sites can be identified as being contemporaneous with such warm or cool periods, however the identification of exactly which of these alternating periods in which the site falls would be impossible unless the chronological association of an index fossil can be shown. The elephant is an example of a useful index fossil in dating in that there are three distinct speciations of the animal which further divide the Pleistocene into three separate periods in which each of the three types lived (Michels 1981). From this phenomenon therefore, an archaeologist could determine that an artefact found in an eroded context in association with Elephas primigenius, for example dates to a warm period of the Middle Pleistocene. Despite the accuracy with which such methods have provided dates, it is important to note that well-preserved macrofauna for dating are relatively rare and that microfauna are more commonly employed for chronological purposes.
Conclusion
In assessing the many and substantial contributions of zooarchaeology to archaeological interpretation and dating, it is difficult to envision sucessful understanding of archaeological remains in its absence. The rise in utilization of zooarchaeology for the reconstruction of ancient subsistence, environmental conditions and in dating processes can be attributed to scientific advances in molecular biology and evolutionary mechanisms as well as the adoption of new methods and approaches to archaeological research and excavation. It can observed that the increased application of zooarchaeological methods to interpretation and dating have greatly improved our understanding of human activity that would otherwise have been unattainable by other methods. Although the uses of zooarchaeology in archaeological interpretation are widepread and by no means exhausted by the examples provided here, several unifying limitations can be seen where certain factors must first be determined prior to the application of faunal remains. Whether aimed for the determination of ancient climate and population or for subsistence reconstruction, a context must be established which relates archaeological remains to faunal remains. The archaeologist must also determine how the fauna became deposited in that context, either by human agency or natural causes. Having accomplished this, the archaeologist can expect to extract invaluable information from the ancient fauna, being limited only by what he fails to unearth.
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