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Physical anthropology

Description

Physical anthropology describes a research field that deals with human remains from an archaeological context – usually skeletal remains from burials or cremations, and, in rare cases even mummies.

Application

The goal of the research on skeletal material is to collect basic biological data such as gender, age at death, height and proportions, routine-specific activity patterns, diagnosable diseases and, if applicable, the cause of death. Furthermore, inferences on lifestyle, nutrition, disease burden, as well as social and migration behaviour can also be made. And, depending on the context, even a spatial and temporal comparison between populations is possible. The application range of physical anthropology is very broad.

Basics

The work on the human remains begins with an assessment of the state of preservation. A distinction between qualitative and quantitative conservation is made. The qualitative preservation refers to the preservation of bone substance and bone surface. Quantitative bone preservation assesses the representation, i.e. the extent to which all parts of the skeletal anatomy are available and how far the fragmentation of the individual skeletal elements has progressed. If both qualitative and quantitative preservation are well maintained, various characteristics can be determined, ranging from sex, age and height to potential pathological changes. All of this information can be retrieved entirely on the basis of the skeletal material.

Methoden-physische-anthropologie
Fig. 1: Recording of skeletal material (Photo: CEZA)

The biological sex can be reliably determined from the pelvic and cranial characteristics. The assessment of the overall shape of the pelvis, which is rather broad and shell-like for women from the front and top, but narrow and high for men, is only possible if both pelvic parts and the sacrum are available and the pelvis can be reconstructed. Since this is only possible with a particularly good skeletal preservation, the alternative is to rely on features that are recognisable in specific areas of the pelvis. The sex determination on the skull, which is also possible, is however always afflicted with more uncertainties, so that the examination of the pelvis is ideally preferred.

When determining the age at death, it is important to note that this can be reliably determined in children and adolescents up to about 15 years of age, mostly on the basis of tooth development. The age determination of adult individuals, on the other hand, is much more challenging. In these cases, the age at death is often determined by the closure of the large cranial sutures. Age dependent changes, especially in joints that endure less strain, can also indicate the individual age. The abrasion (wear) of dental crowns, for example, serves as an indication for the progressive degradation of the supporting internal bone structure (cancellous bone) of the proximal humerus and femur. However, currently the best approximation to the calendar age of death of adult skeletons is achieved by means of the growth rings in the dental cement, the tooth cementum annulation (TCA) method. All of these methods are used at CEZA.

The body height estimation, which is also regularly requested, is one of the standards of morphological examinations. It is based on the determination of the longest length of the long bones, and their presence is accordingly a prerequisite for this step. Afterwards, the height is calculated, using several regression formulas. However, all formulas should be calculated individually and the arithmetic mean should be generated from the results. Finally, certain pathologies can also be diagnosed on bones, with the most common pathologies being dental diseases, followed by joint diseases, infections, and traumas. Even chronic infectious diseases can often be diagnosed. In unclear cases in which the disease cannot be precisely diagnosed, a detailed description and documentation is prepared.

Limitations

In general, the limits of the methods are closely linked to the state of preservation and the completeness of the finds. In concrete terms, a major source of problems with the accessability of the results lies in cremation: burnt skeletal remains differ from unburnt ones. Since the bones shrink, deform and break during the burning process and the pyre is often extinguished with liquids that lead to further fragmentation due to the temperature shock, the determination of sex, age, and diseases is considerably more difficult in such cases.

Another limit of physical anthropology lies in age determination: To date, there is not a single morphologically based method of age estimation that can precisely indicate the age of death. Therefore, as many characteristics as possible should always be considered for a determination of the age at death.

Researchfocus

Materials