Looking into the demography of an iron age population in the Western Mediterranean. I. Mortality

In this paper, we attempt to reconstruct the mortality pattern of the population buried in S'Illot des Porros (Majorca), an Iron Age necropolis in the western Mediterranean, by means of paleodemographic analysis. The skeletal sample consists of 285 individuals, 93 subadults (under 20 years old) and 192 adults. The aim of this study is twofold: first, to identify and to evaluate the structural anomalies of the skeletal sample, and second, to obtain a possible and realistic description of the biological dynamics of this population, with special reference to its mortality pattern. The study uses current demographic methodology and several demographic models (for comparison). An abridged life table was built to estimate the mortality parameters. To evaluate the likelihood of the estimated data, an indirect analysis, which consisted of a comparison of our results with different population models (Weiss [1973] American Antiquity 38; Coale and Demeny [1996] Regional Model Life Tables and Stable Populations. Princeton: Princeton University Press; Ledermann [1969] Nouvelles tables - types de mortalite. Paris: Presses Universitaires de France), was carried out. An important bias was identified in the case of children, mostly affecting infants but also children between the ages of 1 and 5. This was interpreted as a census error due to taphonomic reasons and to an excluding differential funeral rite. A life expectancy at birth of approximately 28 years was estimated from the observed data. When this bias was removed, the estimated life expectancy at birth dropped to 23 years. The use of the Brass logit system allowed us to sketch a possible mortality profile for this population: low life expectancy, high infant mortality and hard life conditions, which were the cause of the low levels of survivorship in old ages.