Ossuary deposits present special challenges and opportunities to the researcher. By definition, ossuaries contain multiple individuals, frequently commingled and disarticulated. Such samples present challengers in excavation, as well as analysis, especially in sorting out single individuals, developing estimates of the number of individuals represented and evaluation of sex and age at death.
In some contexts, social factors leading to ossuary burial are at least partially known, providing opportunities to assess key sampling issues important in demographic reconstruction. In the Mid-Atlantic area of the United States and the Great Lakes area of southern Canada, ethnographic information suggests that such ossuaries culminated from social practices in which the Indian groups periodically assembled the remains of their decedents for communal burial. Each ossuary represented a specific period of time and the groups went to great efforts to include all who had died since the previous burial ceremony. The resulting ossuaries thus address two of the major concerns in palaeodemographic reconstruction, namely the extent to which all decedents are represented and the time period represented. If preservation is favorable, the ossuaries represent prime samples for demographic study.
In 1953 and 1971, two ossuaries were discovered in the Mid-Atlantic area of the United States. Excavation and analysis revealed that at least 131 and 188 individuals were represented respectively. Ages at death were estimated using a variety of techniques, but demographic reconstruction focused on what were believed to be the most accurate and relevant methods given the state of bone preservation and representation. For subadults, age was assessed using standards of dental formation. For adults, ages were estimated utilizing histological methodology applied to ground thin sections taken from the femoral midshafts.
The resulting ages at death were assembled to form mortality curves, survivorship curves, and life tables. An example of the life table reconstructed from the second (larger) ossuary is presented in Table 1. The life table presents agespecific mortality information for successive 5 year cohorts but suggests a life expectancy at birth of about 23 years.
A product of life table reconstruction can be the crude mortality rate (number of individuals dying per thousand per year in the population). This statistic can be computed directly from the life expectancy at birth value; for the larger ossuary, the figure was 43.5. This suggests that the death rate for the population represented was 43.5 per thousand in the population per year. The total number of deceased individuals was known through analysis (188). The number of years represented by the ossuary (about three years) was estimated using archaeological information (extent of articulated individuals vs. nonarticulated individuals). Using this information, the size of the contributing population could be estimated (approximately 1441 persons). This estimate could then be considered with site survey information as well as ethnohistorical sources for an overall anthropological evaluation of the mortuary site and its cultural context.
World History
