Resurrecting Pompeii (25 page)

Estimation of age-at-death is more dif ficult than the attribution of sex from skeletal material as there are only two options for sex, whilst ageing is a continuous process. This means that it is virtually impossible to age individuals, especially adults, with a great deal of precision. A further problem for the estimation of age-at-death is that an individual’s biological age may not reflect their chronological or actual age. This is because the relationship between the degree of skeletal development or degeneration and the actual age of an individual is not linear.
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Juvenile skeletons generally produce the most reliable results. Criteria for age determination of immature individuals are relatively straightforward as they are based on growth and development. While there is some variation between individuals and populations in timing, these factors tend to be relatively consistent and predictable. Juvenile age-at-death is generally determined by extrapolation from standards that have been derived from data obtained from children of known age from modern populations. A number of variables may influence this, such as illness and nutrition. Ideally, it is preferable to avoid the use of ageing criteria that are likely to be affected by such variables. An example of this can be seen in the size of bones, which tends to be a good indicator of foetal age. Apparently, poor maternal nutrition is less likely to affect foetal bone length than malnutrition after birth. Bone length of a growing child is subject to too many external influences to be a really useful indicator of age. The incomplete nature of most archaeological remains, however, makes it impossible to discard any evidence, even if it is problematic.

Teeth develop from the crown to the roots, with root formation continuing to completion after the tooth has erupted. Dental development tends to be complete by the beginning of the third decade of life, though the last tooth to erupt, the third molar, or wisdom tooth, is the most variable. While there is some variation between individuals, teeth tend to be reliable indicators of the age of sub-adults, as their development appears to be less influenced by environmental factors. This would also suggest that the modern standards for tooth formation and eruption are applicable to ancient populations. This theory was tested, using 63 named and well-documented skeletons of children from the Spitalfields crypt. Though they only date back as far as the eighteenth and nineteenth centuries, it is notable that there was a high correlation between documented age and the results obtained from a number of standard dental ageing techniques. The ages obtained from the dental standards minimally, but consistently, under-aged the Spitalfields children. It has been suggested that this is a reflection of the effects of poor nutrition on dental development.
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After teeth, skeletal development provides the best indicator of juvenile age-at-death. Growing long bones are made up of three parts: the shaft or diaphysis and the ends, which articulate with other bones, which are known as the epiphyses. The epiphyses are separated from the shaft by growth cartilage, which is where growth occurs. When the growth period ends, the cartilage ossifies and the epiphyses are fused with the shaft. The majority of other bones also have epiphyses. Epiphyseal fusion occurs in an orderly fashion in the period between adolescence and early adulthood. The actual age at which epiphyseal fusion occurs for different bones can vary between individuals, sexes and populations. Epiphyses tend to fuse earlier in the bones of females, whose period of growth is generally shorter than that of males. The last epiphysis to fuse is that of the medial clavicle or collarbone. The age of fusion for this epiphysis can vary between 21 and 30 years of age, though generally all bones have fused by about 28 years of age in modern populations.

The determination of adult age-at-death is fraught with problems. After the completion of development, the only changes that occur are essentially degenerative and individuals do not degenerate at the same rate. This is readily apparent on living people. Some people’s hair, for example, goes grey when they are in their early twenties, whilst others can naturally retain their colour into old age. Differential degeneration is a biological fact that cannot be accounted for by any ageing technique. The sequence of changes after maturity is attained is variable and tends to be influenced by environmental factors; for example, the degree of tooth wear or attrition observed on an individual is determined by diet and lifestyle. Even with entire skeletons, it is difficult to establish the age-at-death of an adult. The addition of further complicating factors, such as a disarticulated unknown population, exacerbates the existing problems.
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As with the determination of sex, age-at-death can be more con fidently assessed with complete skeletons. The constraints of the Pompeian skeletal sample limited the use of certain ageing techniques; for example, it was virtually impossible to employ a standard multiple trait assessment based on the examination of the entire skeleton.
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Due to limitations of time and budget, emphasis was placed on the techniques that were deemed most useful at the time. The choice of the pelvis, skull and teeth as the indicators of age-at-death in the Pompeian sample was based on their well-documented potential to provide age information from birth to relative old age.
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Criteria that were used to give an indication of adult age included changes to the surface of the pubic symphysis, ectocranial suture closure and tooth wear. Assessment based on dental attrition was of limited value for this sample, as most of the skulls can no longer be articulated with mandibles due to the manner in which they were stored. This meant it was not always clear whether wear related to occlusal problems or dietary behaviour. Consideration was also given to a number of cranial features, which could be used to separate adults from juveniles, such as fusion of the basi-sphenoid and development of the frontal sinuses. Though less reliable, features like endocranial suture closure were also recorded, especially when only limited material representing an individual was available.

Age-related pathology, such as hyperostosis frontalis interna (Chapter 8 and see below), was employed to give an indication of the relative longevity of the Pompeians. The range of bony indicators generally associated with advancing years that could be used for this purpose was determined by the disarticulated nature of the sample. For example, it was not possible to do more than note most cases of osteophytic change, as age-related arthropathy cannot necessarily be distinguished from trauma-related changes when examination is based on a single bone. Some scholars have argued the possibility that certain disorders associated with old age in a modern Western population occurred at comparatively earlier ages in an ancient population. It was therefore necessary for their association with elderly people to be corroborated by other skeletal age indicators.

There was relatively little advantage to be gained from an examination of all the samples of specific bones in the disarticulated Pompeian collection to establish age-at-death. Since the times of epiphyseal closure vary between bones in an individual, a study of the degree of epiphyseal union in all these samples would do little more than separate adults from juveniles.
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For this reason only one post-cranial bone, the pelvis, was chosen to represent the entire sample. The degree of epiphyseal union was routinely recorded for juvenile bones that were included in non-metric trait scoring for long bones.

One of the constraints of this project was that it was not possible at the time of examination to obtain permission to perform destructive tests on Pompeian skeletal material. This precluded the use of various established methods, including bone cortex remodelling and root dentine transparency in teeth.
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It is notable that research by the Victorian Institute of Forensic Pathology at Monash University has produced results that question the reliability of the former method.
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Access to radiographic techniques, such as those suggested by Iscan and Loth,
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was also not possible due to financial constraints. This meant that the determination of age-at-death in this study was limited to macroscopic observations.

It is misleading to ascribe exact ages to archaeological skeletal material from an unknown population for two reasons. First, the actual ages for epiphyseal fusion, dental eruption and subsequent degenerative bony changes associated with ageing are variable. Variation for all these changes can occur within and between individuals and populations. In addition, it can be correlated with sex.
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As a result of these variations tolerances in age estimation can vary considerably. For example, those produced from the Suchey–Brooks technique of ageing from the pubic symphysis have tolerances (95 per cent) of between ± 5 years for phase 1 to well over ± 20 years for the later phases (see Table 7.1).
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Second, age estimates that have been established for skeletal material have been determined from modern Western samples. There is a standard sevenpoint scoring scheme to estimate relative age.
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Two additional scores were included in this work to deal with some of the vagaries encountered with the establishment of adult age-at-death (Table 7.2). This system roughly classifies age in ten-year increments, as the order of accuracy of most available techniques is very poor. It must be remembered that these age ranges are artificial as age-related changes are continuous.
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It is also important to understand that the classification of the last phase as relating to the sixth decade or older is purely a reflection of the upper limit of the techniques. It in no way is meant to indicate a shorter lifespan.

The juvenile innominate bone is composed of three separate bones, the ilium, the ischium and the pubis. In a modern Western population the rami of the pubis and the ischium generally fuse in about the seventh or eighth year of life, though fusion can occur any time between the ages of five and eight. In about the twelfth year of life the cartilaginous strip that has separated the three bones begins to ossify. It can take up until the eighteenth year for ossification to be completed at this point. Epiphyses appear at the iliac crest, the anterior inferior iliac spine, the pubis and the ischial tuberosity at about puberty and fusion is usually completed by the twenty-sixth year. It should be noted that fusion occurs at an earlier age in females. In the case of the ilium, ischium and pubis, fusion occurs between the ages of 11 to 15 in females and 14 to 17 in males in modern Western populations. Various factors can influence the time of fusion including health, diet and the state of the endocrine system. In addition, there may be differences between populations.
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Correlation has been observed between maximum iliac breadth and juvenile age. The data that have been collected from a North American Indian population have been tabulated as a series of means, standard deviations and ranges of deviations for different age ranges and presented for comparison with other populations. It is important to note that comparative studies of growth rates between different populations have demonstrated that there is interpopulation variation in the rate of bone growth, e.g. the rate of growth of Americans of European heritage has been found to be greater than that of American Indians, which in turn has been shown to be faster than that of Inuit. This suggests that though these data were most appropriately applied to other American Indian populations, they could be used with caution to obtain a general estimate of juvenile age-at-death for other populations. Even greater caution is required as some of these age-at-death estimates have been based on extremely small sample sizes, e.g. estimates for juveniles between 10.5 and 11.5 years of age were based on a sample of one bone.
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The use of North American Indian material for comparison with the Pompeian sample is far from ideal but no other data were available at the time of study. It did not enable exact ages to be assigned to individual bones but it did enable the juvenile pelvic remains to be seriated.

Out of 196 left innominate bones available for examination in the Pompeian collection, 6.1 per cent were completely unfused. Comparison of the maximum width of the eleven bones in this category that could be measured with the mean ages established for North American Indian populations from maximum iliac width, indicated that the younger immature individuals in the Pompeian sample fell within the juvenile category with ages consistent with a range in modern Western populations of between about three and twelve years. Bearing in mind the problems of extrapolation between populations, rough age estimates are presented here purely to give some indication of the range of development of the juvenile pelvic bones in the Pompeian sample. In summary, approximately 11 per cent of the sample presented as juvenile, reflecting an age range consistent with 2.5 to 15.5 years. A roughly even distribution of juveniles for each of the ages in this range was observed.

Since it was not possible to relate clavicles to pelves in the Pompeian collection, only epiphyseal fusion of the iliac crest was recorded. The value of these observations is that, in theory, they give some indication of the age of adolescents and individuals in the early years of adulthood. In the current study, fusion of the anterior iliac crest was only used to distinguish between adolescents and adults. In modern Western populations, the anterior and posterior epiphyses fuse to form a single cap for the crest and then commence fusion with the pelvis from 15–18 years in females and 17 to 20 years in males. Fusion tends to be complete by 23 years of age.
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There were 15 cases, or 7.65 per cent of the sample, which exhibited partial union of the epiphysis at the anterior iliac crest. It was possible to measure two of these cases. The widths of both bones were found to be significantly larger than the North American Indian comparative data for older adolescents.

The pubic symphysis is the joint where the left and right pubic bones almost meet. They are separated by a fibro-cartilaginous disc. The underlying bone at this joint displays progressive degenerative changes during adulthood. In younger adults, the surface is distinguished by a series of ridges and furrows with no clear margins. Over time, the ridges become less defined and the surface is delimited by margins. The surface of the pubic symphysis is marked by increasing porosity and a pitted and uneven appearance in older age. Emphasis has been placed on the use of the pubic symphysis for the estimation of adult age from the pelvis since 1858, when age related changes were first observed at this site.
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In 1920, Todd introduced a set of ten developmental phases for the identification of age-at-death. Though he observed some differences, he did not really account for differences between populations or between the sexes as a result of pregnancy and parturition in females. His system was modified by Brooks in 1955 to correct its tendency to overage individuals.

McKern and Stewart attempted to deal with the problems of variability at the site of the pubic symphysis and introduced a method which involved the individual analysis of morphological components to estimate male age. Gilbert and McKern later attempted to develop a set of standards that could be applied to female pubic symphyses. Their method was criticized by Suchey for not adequately addressing the issues of interobserver error and changes to the region as a result of pregnancy and parturition. Meindl
et al
. conducted blind tests on all the available methods of age determination from the pubic symphysis. They reduced Todd’s ten phase system to five which they considered had the dual advantages of dealing with variability and of being simple to use.
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The innominate bones with complete pubic symphyses were separated by sex. The male and female groups were then seriated, based on comparison with a set of casts of the pubic region that were produced for the estimation of age-at-death using the method developed by Suchey and Brooks. Each bone was then assessed separately using the appropriate set of casts. The determination of age-at-death from the Suchey–Brooks method was made on a number of occasions without reference to earlier assessments and with a considerable period of time (up to two months) separating each examination. The degree of concordance between assessments was found to be close to 100 per cent.

It is clear from the table for age estimates based on the pelvic sample (Table 7.3), that the majority of the sample (81.1 per cent) is made up of bones that have been interpreted as adult. There were 160 cases, or 81.6 per cent of the sample, where pelvic fusion was complete.

Only 84 pubic symphyses were complete enough to enable age estimates to be made based on the Suchey–Brooks male and female sets of casts. The results of the raw Suchey–Brooks scores are presented as a histogram (Figure 7.1; also see Table 7.4). They reflect the pooled results for both sexes. The age estimate of 17 individuals, or 8.7 per cent of the sample, was consistent with the third decade of life in a modern Western population. Sixteen of