Sex and age estimation
Age at death and the sex of skeletons both have to be estimated if a demographic profile is to be created of the population under study. These results can only ever be considered as ‘estimates’ because there are a range of factors that can make precision difficult or even impossible to achieve (e.g. poor preservation of the skeleton). At times it may only be possible to say that a skeleton possibly or probably comes from a male or female, and that they were of ‘adult years’.
Age at death
‘Non-adults’ (the term which bioarchaeologists use to refer to those aged under 18 years) were still growing when they died and age estimations are based on the stages of dental development and eruption as well as on the development and size of their bones. For adults, age at death is estimated on the basis of degenerative changes, particularly to the joints of the pelvis and ribs, supplemented by an analysis of the wear on the teeth.
The graph shows the data for age at death for the Palace Green skeletons. Overall, twelve (42.9%) of the articulated skeletons were identified as adolescents. Five of these were 13-16 years of age, and seven were 16-19 years. Two-thirds (68.8%) of the sixteen adults were aged 17-25 years of age. One person was an adult of 36-45 years, and another was a mature adult aged over 46 years of age; the age of the other three adults could not be estimated.
Age at death of all the skeletons recovered during excavation © Anwen Caffell, Durham University
Estimating the sex of skeletons can only be carried out reliably in adults because non-adults have not grown and developed to the point where their bones and teeth show the features of their sex. The pelvis and skull (cranium and mandible) are the key parts of the skeleton used for this, supplemented with measurements of other bones. Thirteen (81.3%) of the sixteen adults in this group proved to be men. The sex of the remaining three adults could not be estimated because the relevant parts of the skeleton were not preserved. Four of the older adolescents were also tentatively thought to be male; there was no evidence for women among the remains. Analysis of the human DNA trapped in the dental calculus of 12 individuals later confirmed this overall conclusion.
Sex estimation of all the skeletons recovered during excavation © Anwen Caffell, Durham University
Mass graves associated with catastrophic events, among them plague or famine, will include women, children and the elderly - that is to say a more representative sample of the population. This is because everyone in the population is potentially affected. A demographic profile (age at death and sex) heavily biased towards young adult men, on the other hand, suggests a link to warfare and conflict. Several parallels can be found in the archaeological record. The 47 individuals recovered from a mass grave associated with the Battle of Lützen (Germany) in 1632 were probably all men aged between 15 and 50 years; their average age was around 28 years. The 113 skeletons found in ten mass graves at All Saints Church, York (UK) and associated with the siege of York in 1644 were mainly men (87 identified) ranging in age from adolescents to around 50 years; their average age was late 30s or 40s. However, there were also six women buried there.
© Durham University