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Many studies have been carried out into the impact of smoking on the human body, and one need only to glance at a pack of cigarettes to be confronted with imagery detailing some of the consequences in gory detail. In terms of historic remains, however, can smokers be spotted in the archaeological record – and can we see a change in public health after tobacco was introduced to Britain in the 16th century? Contemporary records lack the data required to understand fully how smoking and other methods of tobacco-consumption affected the health of past populations, and archaeological evidence has thus far not been fully explored as an avenue to answer these questions. A new study by archaeological scientists and biomolecular specialists at the University of Leicester, however, has sought to change this by analysing skeletal material in order to determine whether historical tobacco-usage can be recognised in human remains from archaeological contexts.
Previously, the easiest way to identify tobacco-use in excavated individuals was by examining their teeth – staining, and the characteristic ‘pipe notch’ worn between teeth through frequent pipe-use (pictured below), are both common indicators of someone’s smoking habits. However, where teeth have not survived, or are in such poor condition that they cannot be analysed, different techniques are required. Similarly, dental remains do not reflect tobacco-users who enjoyed their habit through other means, such as taking snuff, or through enemas – a common medical treatment until the 19th century.
The new study – funded by Dr Sarah Inskip’s Future Leaders Fellowship as part of UK Research and Innovation’s Arts and Humanities Research Council – therefore sought to establish whether we can see the effect of tobacco-use in an individual’s bones. Human bones are excellent at preserving small molecules called metabolites within their matrix, which makes them extremely valuable resources for studies of this kind. By examining the molecules in the hard outer layer of bones, known as cortical bone, scientists are able to come to conclusions about the conditions under which an individual was living.
For this particular analysis, the researchers selected 323 individuals from two British collections of osteoarchaeological material. The first group consisted of 177 skeletons from the 18th- to 19th-century urban cemetery of St James’ Gardens Burial Ground in Euston, London. The second was a selection of 146 individuals from a rural church in Barton-upon-Humber, north Lincolnshire. Within this latter group, 45 were selected as a control for the study, since they had lived and died before 1500, prior to tobacco being introduced to Europe.
The researchers began by studying the teeth of all the chosen individuals. Evidence of tobacco-use could be seen in 90 cases, while 68 showed no such evidence, and 153 had such poor dental preservation that no conclusions could be drawn. The next step was to establish whether there was a discernible difference between the bone metabolites of those individuals who were characterised by their dentition as non-tobacco-users, those whose teeth showed evidence of tobacco-use, and those who pre-dated tobacco. Any such differences could then be used to determine whether those whose dentition had not survived were tobacco-users or not.
The team used liquid chromatography high-resolution mass spectrometry (LC-HRMS), a powerful analytical technique that identifies and characterises compounds such as lipids (fats), peptides (short chains of amino acids), and alkaloids (organic compounds containing nitrogen). The results could then be compared between the determined tobacco-users and non-users in order to establish whether there were any detectable identifiers in their bones to help categorise them.
First, 504 samples were taken by microdrilling the bone to expose the cortical bone, from which 70mg samples could be obtained from each individual. The samples were then randomised and 40mg from each had the metabolites extracted and tested. Using this method, the researchers successfully identified 45 discriminating molecular features that differed when comparing tobacco-users and non-users. None of these distinctions were particular to a certain age group or biological sex, which suggests that bone metabolism is affected equally among tobacco-users across both categories.
Thus far, research on the molecular makeup of cortical bone has been very limited, within both archaeology and wider scientific research. While further validation work is required in order to determine the features of tobacco-users versus non-users with certainty, this innovative research has many potential applications. For example, the team hope that ongoing research in this area will determine how the differences in bone make-up between tobacco-users and non-users emerge, as this may aid understanding of why tobacco-use is a risk factor in the development of some musculoskeletal and dental disorders. The study is therefore relevant to modern medical research, as well as to investigations of the health of past societies.
The full research article has been published in Science Advances, and is available to read for free online: http://www.science.org/doi/10.1126/sciadv.adn9317 (open access).
Text: Rebecca Preedy / Image: University of Leicester
