Resurrecting Pompeii (21 page)

survival of landmarks. Where there is a bias towards the destruction of the more gracile skeletal material, it is very slight, as can be seen in the measurements of biasterionic breadth,
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basion-nasion length,
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occipital chord
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and the frontal chord.
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Bizygomatic breadth, which reflects the greatest bone damage of the twelve measurements is, if anything, skewed towards bone loss in the more robust end of the sample. This is also true to a lesser extent for basionbregma height,
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maximum frontal breadth and biauricular breadth.
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Visualization of the con fidence in each measurement made it possible to establish which measurements could reasonably be used and which should be either discarded from analysis or interpreted with due caution. It was apparent that bizygomatic breadth was not very reliable and, where possible, was not included in statistical analysis of the Pompeian skull measurements. It is notable, however, that when it was used the results were comparable to those of other populations. It is possible that the bizygomatic breadth

Although it might be expected that the ‘crumble factor’ would have greater impact on the more gracile bones,
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these graphs show that there was at least equivalent bone destruction in the more robust end of the sample. Assuming the sample is made up of both males and females, these results indicate that there is no significant differential bone survival for the adult material and that the use of multivariate statistical analysis should not produce results with a sex bias.

Initially, emphasis was placed on the use of descriptive statistics to assess the potential value of different types of bones as descriptors in this disarticulated collection. Both univariate and multivariate methods were employed. The combination of the two types of data analysis fulfils several functions. Univariate statistics, which describe a single variable at a time, were used to ensure that all the data were presented and to establish whether any distribution trends, such as skewing, normality or bimodality, were immediately apparent. It is a valuable way of describing the data in a compact form by simple graphics, such as histograms, and statistics, such as range, mean and standard deviation. The results of these analyses can easily be compared with data from other sites. These analyses are essential for the appropriate application of the data to predictive models, such as the determination of stature from femur length from samples of unknown sex.

Multivariate methods, or those that deal with a number of variables at the same time, correspond more closely to the way humans obtain and analyze information. For example, we process a raft of variables to identify and classify archaeological material. The main value of employing multivariate techniques is that they enable all the available data for bones with complete data sets to be viewed at once, revealing underlying structures and trends which would not be apparent from single variables. These techniques are particularly useful for unknown and incomplete samples. However, one of the main problems encountered with incomplete material is missing values.

Statistics copes with missing values in two ways. The first is to either delete variables that contain any missing values, or exclude objects that do not have values for one or more variables. The second is to replace missing data with average values based on those of the other data. Both these methods have their disadvantages.

Deleting objects that have missing values may not only signi ficantly diminish the sample size but can also skew the sample. It could be hypothetically argued that, in the case of some skeletal material, the more robust bones may have a higher survival rate. This means that incomplete bones could represent females. Deleting variables with missing measurements or observations preserves the sample size but can result in the loss of a large number of the variables. Replacing missing information with average values maintains sample sizes but this method is based on the assumption that all cases are similar, which does not necessarily reflect the bones in the sample.

Averaged values were not used in this study. It was considered that even though deleting missing cases could affect the integrity of the sample, the use of average values would be far more misleading and a greater source of potential error. In some cases multivariate analysis was not possible because of the large number of missing values in certain data sets. In these cases bivariate analyses comparing two variables at a time were undertaken.

There are a large number of multivariate techniques that could be used to analyse skeletal data. All statistical techniques have assumptions that must be met for their appropriate use. This is especially true for multivariate techniques. For example, discriminant function analysis
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could not be applied to the Pompeian skeletal data as it is based on data sets derived from known populations. This standard technique is used in archaeological and forensic applications to place unknown individuals from a known population into their correct group for characteristics to establish sex or population affinities.

Facial reconstruction involves the combination of scienti fic and artistic techniques to re-create soft tissue facial features from a skull. Some scholars consider the term facial reconstruction to be misleading as it suggests a greater degree of certainty than the technique provides, and prefer to use ‘facial approximation’ as a descriptor.
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These techniques cannot produce an accurate reproduction of a face because the available evidence does not yield information about a number of features, such as the ears, hair, lips, nose, eye colour or the amount of fatty tissue.

There has been some research about the reliability of facial approximation in forensic applications. This has been possible because the results can be tested against a known individual when a match is made. In a serial murder investigation in the USA, a number of artists created approximations of facial features from the same remains with the same baseline information about sex, age and population affinity and produced significantly different results. The main differences were in the interpretation of soft tissue, which resulted in variation for eyes, noses and profiles. There was greater consensus for areas like the cheekbones and chin.
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A further problem that has been observed with regard to facial approximation is the tendency for artists to incorporate their own facial features into the reconstruction and produce visages that bear more resemblance to themselves than the subject.
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These problems are exacerbated when reconstruction techniques are applied to archaeological material as the results cannot be validated. Facial approximation is also not generally considered to be an essential osteological research tool and tends to be used only as a means of making individual skeletons more accessible to the broader public. One could reasonably argue that in the case of Pompeii, the casts already serve this purpose (see Chapter 10).

Despite the loss of considerable skeletal information, as a result of site management in the eighteenth and nineteenth centuries, it is still possible to obtain a substantial amount of data from the remaining bones. Given the paucity of available Roman skeletal material representing the first century
_AD
due to the practice of cremation, the Pompeian skeletons provide an important source of population information for this period.

There are virtually no ideal archaeological sites or samples. As with the disarticulated human skeletal sample from Pompeii, it is important to acknowledge the constraints associated with the material under investigation so that a specific research design can be developed to deal with these problems. The Pompeian skeletal evidence provides tantalizing and sometimes ambiguous glimpses into the lives and deaths of the people who became victims at this site. This study demonstrates the potential of what at first appears to be an extremely difficult data set.

Perhaps the greatest frustration for a number of scholars has been the fact that so much information about the Pompeian skeletal sample was lost through post-excavation processes. Though compromised, the collection of human remains that survive from Pompeii can still provide a wealth of information. Various methods can be applied to obtain a profile of the sample of victims in terms of sex ratio, ages-at-death, general health and population affinities.

Apart from providing us with insight into the lives and deaths of the people who became victims, this information can be used to test the assertion that the old, infirm, very young individuals and women made up the majority of the victims (Chapter 5).
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Some authors have offered remarkable reasoning to account for such claims. Massa,
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for example, stated that more women than men were discovered amongst the victims as ‘the wife and mother preferred to die than survive alone’. He also considered that women were more attached to their possessions than men and that a number died trying to save their jewellery and other valuables.

Associated artefacts were traditionally used to establish the sex of victims found during the course of excavations. For example, sex and age attributions were made for 194 of the thousand-plus victims documented in the excavation diaries. Of those that were identified as adults, 78 were said to be female on the basis of associated finds of earrings, necklaces and other jewellery and 35 were recorded as male.
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Physical anthropological techniques were not routinely applied for the determination of sex of
in situ
skeletal finds until the latter part of the twentieth century. Obviously, there was a need to employ the skeletal evidence to test the assumption that stereotypical associated finds provide an accurate indicator of the sex of an individual.

The reason that we are able to attribute sex to an individual skeleton is because sex-related differences can be observed on adult human bones. It is difficult to determine sex from juvenile bones because most of the variance between male and female skeletons only becomes apparent with the onset of puberty. Various methods have been proposed for juvenile sex determination but none of these are widely accepted.
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While male testosterone levels are generally very low before the onset of puberty, they do vary throughout development, which means that there are some age groups where it is theoretically possible to make a more reliable attribution of sex. Prior to puberty, male testosterone levels tend to be highest in the foetus from two months until birth. Nonetheless, the differences are too slight to be viewed with the naked eye and are only apparent from measurements on the pelvic bones of a number of individuals from a sample.

Juvenile sex identi fication has been attempted on the basis of statistical studies of sex-related differences, or dimorphism, in the foetal sciatic notch.
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Similarly, a study of the skeletons of children of known sex and age from the historic cemetery of Spitalfields, London, suggested that it was possible to establish the sex of juveniles between birth and five years of age in 70 to 90 per cent of cases on the basis of diagnostic morphological features of the pelvis and mandible.
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Most of these techniques, which are based on minor variations, are not appropriate for the majority of archaeological material as good skeletal survival is required for assessment. The available Pompeian sample, in particular, contained very few remains of individuals below five years of age.

It has been suggested that an estimate of sex can be made by comparing the degree of tooth development with the level of development of the post-cranial skeleton. This technique is based on the fact that there is a faster rate of post-cranial growth in female children, whilst teeth develop at about the same rate. This technique is not generally applicable to archaeological material as complete skeletons are required, along with large samples so that population norms can be established for dental and skeletal maturation rates.
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In theory, it is also possible to use teeth to establish the sex of older juveniles from some populations. It has been claimed that the teeth of males tend to be larger than those of females. As teeth do not increase in size once they are formed, it has been suggested that statistical studies of permanent tooth measurements could be used as an indicator of sex from the remains of children. In practice, this technique is problematic because male and female tooth size varies within and between populations. Further, environmental factors, such as maternal health during pregnancy and the nutrition of an individual in the period of tooth development, may also influence tooth size. In addition to these problems, the differences in tooth size are subtle and both intra and inter observer error can result in misidentification.
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Ultimately, there is no consensus that there is a reliable method for establishing the sex of juveniles from gross inspection and measurement of skeletal material. It appears that while there are morphological differences between pre-pubescent males and females, they are too subtle to enable accurate systematic detection.
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Consequently, no attempt was made to distinguish male from female juvenile bones in the Pompeian sample, as no reliable method was available at the time of research.

In the long run, microbiology might provide more promising techniques for establishing the sex of juveniles from archaeological contexts. Examination of nuclear DNA should theoretically provide a most useful method for the determination of sex from juvenile skeletal remains. It has been claimed that nuclear DNA has been archaeological skeletal material Though this technique has definite potential, it can be quite difficult to obtain DNA that will yield readable sequences from archaeological skeletons where there is poor preservation of organic material.
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It has been suggested that these problems will be minimized by the development of new DNA techniques as well as the application of new methods, like the analysis of the breakdown products of the organic components of tooth enamel.
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To date, DNA analysis of samples from bones from Pompeii and Herculaneum has been very disappointing (see Chapter 9).
successfully extracted and analyzed from