User:Anna karligkioti/sandbox

HISTORICAL BIOARCHAEOLOGY

Bioarchaeology is the discipline that studies human skeletal remains in their archaeological context. Historical archaeology is the study of human activity in past societies, where written records are available. Historical bioarchaeology refers to the study of human skeletal remains from archaeological contexts where written records exist and can help in contextualizing the skeletal material.

Bioarchaeology developed as a distinct discipline during the 1970s but it was at the beginning of the new millennium that bioarchaeological studies started systematically approaching skeletal remains not only as markers of biological information but also placing emphasis on their cultural context. Nowadays, the discipline tries to blend the physical-natural with the cultural to understand the social life and human experience in past societies and inform larger sociocultural phenomena and patterns of behavior. In this direction bioarchaeology integrates life history, biocultural and social science approaches, covering a multitude of research topics such as embodiment, gender , inequality , ethnogenesis , violence , identity , deviance , childhood and disability.

Historical bioarchaeology first appeared when demographic and other written records were used to evaluate ancient health in North American historic cemeteries. The critical analysis and integration of historical documents with archaeological data and skeletal remains is the distinct attribute that enables historical bioarchaeology to reconstruct past societies in a more holistic manner. In order for this to be achieved, various methods are implemented, complementing research questions often arising from the historical and archaeological context.

Demography

Palaeodemography is the study of the demographic profile of past human populations and provides information such as mortality and fertility rates, average life span and other characteristics that express a population’s composition and alterations through time. Any palaeodemographic analysis is based on the estimation of age-at-death and sex.

Age-at-death estimation

Age-at-death estimation methods are based on the recording of physiological changes that happen on specific parts of the human skeleton such as the skull, teeth, pelvis and long bones. For adults, such methods rely on degenerative changes on specific parts of the skeleton, while for juveniles they rely on developmental changes.

Several recent contributions by historical bioarchaeologists have attempted to bridge the gap between biological and social divisions of age, whereby biological age is the number of years that have elapsed since an individual’s birth, and social age is the and culturally constructed age categories in which individuals belong. In order to interpret data in terms of social identity, bioarchaeologists examine the link between biological age and age-appropriate attitudes and behaviors that are socially and culturally constructed in their relative context.

Sex assessment 

Bioarchaeologists use the skeletal differences that exist between male and female individuals to assess the sex of a skeleton. Such differences are seen principally on the pelvis and secondarily on the skull. Pelvic differences are due to the fact that female pelves facilitate simultaneously locomotion and child-birth, whereas male pelves only need to facilitate locomotion. All other skeletal differences are due to the fact that generally males tend to be larger and more robust, while females tend to be smaller and more gracile.

At this point the relationship between sex and gender should be clarified. Gender is the socially constructed identity of being male or female, while sex is a biological feature. Interpretations and associations between osteologically sexed individuals and gendered artefacts are now examined more thoroughly to provide a richer understanding of life in the past. Therefore, the information on biological sex, can elucidate gender roles and gendered behavior in past societies. Indeed, the relationship of sex and gender has recently started to be addressed by bioarchaeologists. This way the limitation of the binary nature of biological sex and the traditional use of heteronormative interpretations of gender roles, have allowed the identification of non-binary or third gender s. For example, Robb and colleagues demonstrated how health patterns in a historic sample from 7th-3rd century BCE Italy were affected by the complex interaction of gender, status and labor.

Pathology

Palaeopathological indicators observed macroscopically or histologically on skeletal remains can offer information in relation to past health and disease. Numerous diseases can affect the human skeleton. These may be ‘non-specific’ in etiology in the sense that they suggest a stressful episode (malnutrition, infectious disease etc.) affected the individual but the nature of the episode cannot be determined. In addition, infectious, metabolic, neoplastic, developmental, hematopoietic, traumatic and many other disorders may be identified on skeletal remains. By assessing past pathology, historical bioarchaeologists can extract information on inter- and intra-population health, interaction between health status and the environment, division of labor, gender roles and social stratification.

For example, Bourbou examined the impact of historical and environmental changes in Byzantine populations from central Greece and Crete and tried to associate social and biological status in two elite populations from Hellenistic and Roman era Crete. To test how individuals were affected by these changes, she analyzed the presence of dental diseases, metabolic disorders, degenerative joint diseases, Schmorl’s nodes, infections and trauma.

Activity

Activity patterns have been skeletally reconstructed by the analysis of degenerative joint diseases, Schmorl’s nodes , entheseal changes and long bone cross-sectional geometric properties. During our lifetime, the cartilage covering the articular joint surfaces gradually degenerates, causing osteoarthritis. In the spine, mechanical loading additionally, puts pressure on the nucleus pulposus, which results in pits and grooves on the vertebral body (known as Schmorl’s nodes). Entheses are the connective tissue that links muscles to bones via tendons or ligaments. Entheses tend to degenerate throughout an individual’s life course, due to stress caused from repetitive movements. This procedure results in new bone formation or resorption on the site of muscle attachments (entheseal changes). Lastly, bone tissue remodels itself in response to mechanical stimulation. Thus, by applying biomechanical analysis, bioarchaeologists can estimate the cross-sectional geometric properties of long bones, which provide information regarding bone rigidity to tension, compression and bending forces. It should be noted however, that other factors such as sex, age, diet, genetic and metabolic predisposition, body size, trauma or infection may affect many of the above skeletal markers of activity.

As a typical example, Driscoll and Sheridan tried to reconstruct the life of 5th-7th c. CE individuals buried at St. Stephen’s Byzantine monastery in Palestine. Combining textual sources and activity markers on the skeletal remains of the monks, they found evidence for kneeling, compatible with the ascetical life of the period. Similarly, Baker and colleagues identified the skeletal remains of a seamstress from 5th – 6th c. CE Polis Chrysochous in Cyprus. The authors reconstructed the occupation of the woman based on indicators of squatting in her lower long bones, grooves on her lateral incisors and a needle that had been buried with her.

Diet

Diet can offer insights on past populations’ health levels, how past societies were structured, their subsistence strategies, human-environment interactions and inter- and/or intra-population interactions. Dental health is a key parameter bioarchaeologists examine in order to draw indirect evidence on past diet as specific dental pathologies have been associated with a heightened consumption of carbohydrates (dental caries) or protein (dental calculus).

Dental caries is expressed as localized destruction of tooth enamel, which is gradually enlarged until a cavity forms. While many studies have found an association between caries and diets rich in carbohydrates, other non-dietary factors also affect caries prevalence, such as oral hygiene, hormonal levels, composition and flow of saliva, pregnancies and lactation. Dental calculus is expressed as mineralized plaque and adheres on tooth surfaces. Alkaline oral environments can facilitate calculus formation and since diets high in protein increase oral alkalinity, studies have associated the presence of calculus with a diet rich in protein.

Chemical analysis has also been employed in the reconstruction of past diet. Such analysis uses ratios of stable isotopes from skeletal and dental tissues with carbon (¹³C/¹²C) and nitrogen (¹⁵N/¹⁴N) stable isotope analysis of bone collagen being the most commonly applied. Carbon isotope analysis is based on the fact that plants with different photosynthesis processes (or pathways) yield different isotope ratios, which are reflected in human and animal consumers’ bone and teeth. There are three photosynthesis pathways: C3 carbon fixation (mostly for cereals, grasses and plants that occur naturally only in colder areas), C4 carbon fixation (mostly for maize, corn, millet, reeds, sugar cane, sorghum) and Crassulacean Acid Metabolism (mostly for plants adapted in arid environments). Furthermore, carbon isotope values can inform on some distinction between terrestrial and marine diet, with higher ¹³C/¹²C values indicating marine protein intake or C4 plants. Similarly, nitrogen stable isotope values (¹⁵N/¹⁴N) reflect consumption of animal-derived protein, with marine animals usually having elevated values compared to terrestrial ones. Thus, increased ¹⁵N/¹⁴N values can be indicative of an individual’s diet rich in protein from fish, meat or animal secondary products, while the opposite may be indicative of a diet based on plant foodstuffs (e.g. legumes).

Historical bioarchaeologists in the Aegean have used stable isotope analysis to investigate diet diachronically in historical period populations from central Greece and demonstrated differences in socioeconomic strata of different periods.

Human mobility and biodistance studies

Human mobility in bioarchaeological studies is explored through so-called biodistances and isotope analysis. Biodistance analysis estimates the relatedness or divergence between populations or subgroups within populations based on the analysis of morphological skeletal and dental traits. These traits may be measured or non-measurable but in all cases they express phenotypic characters the expression of which is to some extent controlled genetically.

Strontium (⁸⁷Sr/⁸⁶Sr) and oxygen isotopes (δ¹⁸O), are also used to investigate mobility. Oxygen isotopes enter the body mostly through drinking water. The isotopic signature of drinking water varies regionally according to temperature and other climatic parameters is reflected in the oxygen isotopes of phosphate in tooth enamel. Strontium from the bedrock passes into the soil and groundwater and subsequently into the food chain. Thus, strontium isotopes enter the human skeleton through food and can reflect the bioavailable strontium of the area where the food was produced. Both oxygen and strontium isotopes are fixed in enamel biogenic phosphate during tooth formation thus, when combined, they can provide two parameters for investigating the place of origin of an individual and migration patterns.

Combining multiple skeletal indicators on mobility, stress, activity and pathology, Nikita and colleagues examined life quality in a cemetery from central Greece diachronically. The results, supported by historical evidence, suggested population continuity between the Archaic and the Hellenistic period, an event occurring between the Hellenistic period and the Roman era that differentiated the local gene pool and, finally, continuity between the Roman and post‐Roman periods.

See also


 * Bioarchaeology


 * Osteoarchaeology
 * Historical archaeology
 * Biological anthropology
 * Environmental archaeology
 * Jane E. Buikstra
 * Biocultural anthropology