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Research

 

Current

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Bone-formers and Bone-losers: Factors in Assessing Age-at-death in Skeletal Remains
Insight Development Grant, SSHRC
In collaboration with Dr. Darlene Weston, UBC Anthropology and the Musculoskeletal Imaging Research Group, UBC Radiology


Abstract:

The purpose of this research is to examine human variation in skeletal aging. We are interested in how bone ages throughout the adult lifespan and in the factors that either speed up or slow down this process. The rate of aging varies because the things we do in life affect mineralization of the skeleton and humans behave in a myriad of ways. This is important for bioarchaeology because we use age-at-death as a variable to help reconstruct the biology, behaviour, health, and social structure of past populations. As a result, our methods to determine adult chronological age from observable physical properties of bone must be accurate. The purpose of this project is to gain in-depth, multifaceted knowledge of the process of skeletal aging in adults and to define the relationship between bone quality, musculoskeletal disorders, and associated lifestyle factors from a large computed-tomography (CT) sample of Canadians that will improve the reliability and validity of methods to estimate age-at-death from bone’s physical properties.

 

Knowing an individual’s location on a bone-former/loser spectrum is critical to understanding the frequency and quality of bony lesions that form in response to metabolic processes and biomechanical stimuli, and especially because our current methods to estimate age-at-death are based on these assumptions, but do not currently do a good job of accurately placing individuals into the correct age category. This study will highlight age variation found in very young and very old individuals that do not fit the expected age-progressive pattern of bone formation and bone loss for the very first time. Both sex-specific and lifestyle factors contributing to age-variation will be examined from patient data that accompanies the collection, an exceptional opportunity not available in archaeological contexts. 

As a result, this research will make an essential contribution to how bioarchaeologists interpret age-related changes in ancient skeletons and in forensic contexts and demonstrates the value and uniqueness in using reference CT collections in pursuit of anthropological questions. The wider benefit of these results will extend across multiple disciplines including demography, archaeology, paleoanthropology, criminology, forensic science, pathology, medical imaging, and biology. Cross-disciplinary collaborative study and research partnerships between Anthropology, UBC Radiology and the Centre for Hip Health and Mobility will enhance the potential for impact and strengthen prospective research in skeletal biology, musculoskeletal imaging, and biological aging in the Faculties of Arts, Social Sciences and Medicine.

 

Funding provided by:

The Social Sciences and Humanities Research Council of Canada (SSHRC)

Past Research

Variation in Skeletal Aging

Abstract:

Much information can be gleaned from the skeleton (sex, stature, diet, disease), but calculating age-at-death is by-far the most difficult, hindered by diverse biological and lifestyle factors that produce tremendous variation in how age traits are presented skeletally. For example osteoarthritis (OA), which is related to age, is not an inevitable consequence of growing old, but arthritic characteristics are routinely used as “reliable” old-age indicators in current methods to estimate age from skeletal joints. This study focuses on individuals that do not fit the typical age-progressive pattern of bone formation by comparing young and old age examples of OA in a documented European cemetery sample of adults. Results of this study show that new skeletal age morphologies are emerging contrary to once-typical rates of bone remodeling: young individuals (<40 years) appear old, and oldest adults (70+ years) appear younger than their chronological age. While traditionally ignored, outlier populations may contain exactly the kind of information we are missing to truly appreciate age-variation in skeletal structures. Results of this study will help bioarchaeologists to better interpret the usefulness of arthritic characteristics as age indicators, and presents the first step in working towards revising and improving currently established aging methods from human remains.

Presented in part at the 47th Annual Meeting of the Canadian Association for Physical Anthropology (CAPA), Banff, Alberta.  October 23-26, 2019 (poster).

The Effects of OA on Skeletal Age Markers
PhD Dissertation (defended April, 2016)


Abstract:

Determining age-at-death and skeletal expression of disease has significant theoretical applications in bioarchaeology when aiming to construct the biology, behavior, ecology, and social structure of past populations. Osteoarthritis (OA) is the most commonly found pathological condition in archaeological collections and most frequent musculoskeletal disorder in contemporary populations with onset and severity most closely correlated with advancing age and activity. Joints do change their appearance with age as a result of accumulated use over time (in-vivo behaviors) producing greater severity and distribution of osteoarthritic lesions throughout the skeleton. This fact has a potentially significant impact on our current methods to estimate age from dry bone. The purpose of this study is to determine the effects of primary osteoarthritis on skeletal age markers through an examination of age, body size, and bone robusticity in three modern (19th-20th C.) European cemetery samples for adults of known sex, age, and occupation (N=289).  This research addresses the following questions: Can we use OA to explain cumulative effects of age and mechanical stress on bone quality? How much of the variation associated with OA can be explained by body size, activity or structural adaptation? Does the presence of OA affect our ability to accurately estimate age at death from the adult skeleton?


Results of this research contribute largely to understanding musculoskeletal form and function, activity-related osteological markers, variation of age-related joint pathology, and post-cranial biomechanics, all of which improve the ability to model past populations.  Combining different types of data such as skeletal age-at-death, cross-sectional geometry, and stature and body mass assist in understanding functional anatomy of the hip joint, contributing factors that influence the biology of OA in the proximal lower limb, behavioral attributes in these populations, and the affects of joint disease on skeletal age markers.

 

Funding provided by:

The Canadian Institute of Health Research (CIHR) Vanier Canada Graduate Scholarship (SC)

The Social Sciences and Humanities Research Council of Canada (SSHRC) (HK).

The Shelley R. Saunders Thesis Grant (SC)

The President's Research Scholarship (UVic) (SC)

Activity and Joint OA


Abstract:

Osteoarthritis (OA) is the most common joint disease in human populations with onset and severity influenced by mechanical loading, aging effects, genetics, anatomy, and body mass. As a result, OA generally presents as hypertrophic changes at articular surfaces of synovial joints, but its pathogenesis remains unclear. Understanding the patterning of OA is important to recognize inherent complexities of the disease, but further research is also necessary to understand the role of physical activity and features of osseous change. The multifactorial aetiology of OA requires the incorporation of multiple lines of evidence to interpret individual or population health from bone samples.  

 

Varied approaches to data collection present a number of challenges and benefits. While the challenges include aspects such as statistical design involving diverse data types, one of the most important benefits of integrating different datasets is the ability to address questions that underlie previous assumptions about how to interpret OA in the human skeleton, and to test those assumptions. For example, combining long bone 3D surface laser scans with documented occupational categories allows us to test the assumption that occupation categories reflect activity (e.g. mechanical loading levels). The in-vivo strain environment that drives both degenerative joint changes and bone functional adaptation is complex and variable. Studies of activity-related skeletal changes, such as OA, would benefit from more nuanced approaches to understanding skeletal aging (e.g., changes in bone microarchitecture), particularly in females.  Likewise, body mass and proportions influence the expression of joint OA and bone strength. The relationship between OA and J as reflective of adult activity requires further study, particularly controlling for age, sex, and size effects. Bioarchaeology is a comparative science and research methods of OA must draw upon data from the analysis of several sources to evaluate the interactive process between humans and their social, cultural and physical worlds.

 

Presented in part at the 84th Annual Meeting of the American Association of Physical Anthropologists (AAPA), St. Louis, Missouri. March 25-28, 2015 (poster). 

 

 

Funding provided by:

The Canadian Institute of Health Research (CIHR) Vanier Canada Graduate Scholarship (SC)

The Social Sciences and Humanities Research Council of Canada (SSHRC) (HK).

The Shelley R. Saunders Thesis Grant (SC)

The President's Research Scholarship (UVic) (SC)

Variation in Femoral Robusticity


Abstract:

Biomechanical forces influence long bone diaphyseal morphology and skeletal robusticity is often used to interpret behavioral differences among human populations. While differences in robusticity inform about differences in activity levels between populations, intra-population variances in these measures may inform about variation in behavior.  This study investigates inter- and intra-population variation in femoral diaphyseal robusticity. Cross-sectional geometric properties of the femoral diaphysis were calculated from external contours using a non-invasive 3D laser scan technology for two modern European populations (Lisbon n=62; Sassari n=62).  Size standardized measures of total section area (TA), second moments of area (I), polar second moments of area (J) and indices of diaphyseal shape (ratio of Imax/Imin) were calculated to determine diaphyseal strength at the femoral midshaft.  Coefficients of variation (CV) were calculated for each variable by sex, sample, and occupation (Lisbon only) and tested for equality between groups. Results of CV comparisons demonstrated that variation in femoral diaphyseal strength does not show differences in activity between samples, sexes, or laborer groups (Lisbon males).  While no significant differences in CVs were found between groups, for the inter-sample comparison, Imax displayed the greatest difference (pooled-sexes, CV = 19.5 and 24.6, p=0.07), suggesting a trend towards greater variation among Sassari individuals to load the femur in the antero-posterior direction. The shape of the femoral midshaft does not vary significantly between sexes or samples, supporting results of previous studies wherein low inherent variation of the femur at this location provides greatest optimization of form in relation to functional constraints. The purpose of this study was to compare the amount of variation in CSG parameters between groups; the next step is to determine which samples (if any) display stronger diaphyses (resistance to bending, and torsional deformation) particularly when controlled for both age, and occupation. In addition to this, including upper limb robusticity measures would be useful to effectively evaluate inherent variation in the postcranial skeleton, as well as the addition of other samples with more specific behavioral characteristics (or repetitive loading) such as terrestrial or marine mobility. 

 

Presented in part at the 83rd Annual Meeting of the American Association of Physical Anthropologists (AAPA), Calgary, Alberta. April 7-12, 2014 (poster). 

 

Funding provided by:

The Canadian Institute of Health Research (CIHR) Vanier Canada Graduate Scholarship (SC)

The Social Sciences and Humanities Research Council of Canada (SSHRC) (HK).

The Shelley R. Saunders Thesis Grant (SC)

The President's Research Scholarship (UVic) (SC)

Acetabulum and Age Estimation

 

Abstract:

Rissech et al. (2006) described a method to estimate age-at-death of adult males using seven traits of the fused acetabulum.  This study simplifies Rissech et al.’s (2006) technique and extends its application to adult females.  Rissech and colleagues’ (2006) original scoring method was applied to a sample of 100 known-aged adults (Calce and Rogers, 2011), three variables were selected based on stepwise multiple regression, and ages were collapsed into three broad ranges: young adult (17-39 years), middle adult (40-64 years), and old adult (65+ years).  The revised method was applied to 249 new known-aged individuals from two other samples.  To minimize observer bias, highlight the most critical traits, and encompass more age-related variation, unique digital renderings accompany morphological descriptions of age categories instead of photos. Three statistically significant characteristics highly correlated with age (p<0.05) are capable of estimating age-at-death with 81% accuracy, both sexes combined.  For misidentified individuals the tendency was to underestimate age.  Results of both intra-observer error testing and inter-rater reliability demonstrated a moderate to substantial agreement in scoring between observers.  When estimating the degree of development of features osteophyte development of the acetabular rim was the most inconsistent between observers.  The revised acetabular method shows promise in estimating age for adults, particularly for those over the age of 65 years.

 

Presented in part at the 62nd Annual Scientific Meeting of the American Academy of Forensic Sciences (AAFS), Seattle, Washington. February 22-27, 2010 (podium). 

 

Funding provided by:

University of Toronto Graduate Fellowship

University of Toronto Graduate Research Travel Grant

 

 

Acetabulum and Age Estimation


Abstract:

This study evaluates the accuracy and precision of the acetabulum method of skeletal age estimation, using 100 male os-coxae from the Grant Collection (GRO) at the University of Toronto, Canada.  Age at death was obtained using Bayesian inference and a computational application (IDADE2) that requires a reference population, close in geographical and temporal distribution to the target case, to calibrate age ranges from the scores generated by the technique. The inaccuracy of this method is 8 years.  The direction of bias indicates the acetabulum technique tends to underestimate age.  The categories 46-65 and 76-90 years exhibit the smallest inaccuracy (0.2), suggesting that this method may be appropriate for individuals over 40 years.  83% of age estimates were +/-12 years of known age; 79% were +/-10 years of known age; and 62% were +/-5 years of known age.  Identifying a suitable reference population is the most significant limitation of this technique for forensic applications.

 

Presented in part at the 35th Annual Meeting of the Canadian Association for Physical Anthropology (CAPA), Banff, Alberta.  November 14-17, 2007 (podium).

Taphonomy and Blunt Force Trauma


Abstract:

This study examines the effects of taphonomic processes on blunt force trauma (BFT) through an experimental study involving pig heads. Of particular concern is the possibility that taphonomic changes can create pseudo-trauma and/or conceal evidence of actual trauma. BFT was inflicted on 10 pig skulls using a hammer. The skulls were subsequently exposed to the environment for 12 months. Seven taphonomic changes were evaluated: the freeze–thaw cycle; rodent gnawing; carnivore scavenging; presence/weight of soil; presence/weight of rain and snow; movement/displacement of bones; and discoloration due to sun bleaching and grass staining. Taphonomic effects varied between cancellous, compact, fresh, and degreased bone. Freezing and thawing, exposure to rain and snow, movement of the skulls, and soil erosion altered and, in some cases disguised, pre-existing trauma. Rodent and carnivore activity did not obliterate evidence of BFT. Recommendations for evaluating BFT on remains affected by taphonomic processes are presented. As each taphonomic process outlined by this study has the potential to disguise antemortem injury, the authors propose that one must carefully examine large, circular openings in the skull that may represent the remnant evidence of BFT.

 

Presented in part  at the 32nd Annual Meeting of the Canadian Association for Physical Anthropology (CAPA), London, Ontario. October 28-30, 2004 (podium).

Excavation Methods: Recovering Buried Remains


Abstract:

In cases of scattered or buried remains, forensic anthropological and archaeological methods are used to reconstruct human behaviour and interpret the context of evidence.  The purpose of this research is to evaluate two methods of excavating human remains in support of their ability to: (1) recover all types of evidence; and (2) aid in jury comprehension by conveying information about placement of evidence and body in relation to one another and the grave itself.  Two known burials of pig remains were excavated using two different techniques: (a) the forensic bisect approach and; (b) traditional archaeological excavation. The usefulness of each technique was assessed based on the following four criteria: accuracy in evidence collection, increased probability of collecting all physical evidence, prevention of post-mortem damage, and difficulty in presenting information to a jury.  In both cases we were able to: expose stratigraphy, determine depths, note root cutting, and document tool trauma. Results of this study indicate that both methods are capable of successfully recovering evidence. Tool marks made from digging the grave were preserved in both cases and relationships between all objects found in the strata were established. Major differences between the two approaches include the time necessary to complete the excavation, documentation, and recovery, with the bisect method proving to be a more efficient methodology. In addition, presentation of the evidence to a jury can be complicated by the traditional archaeological approach since contextual information and the relationship of evidence found using the horizontal layering method is difficult for the untrained jury member to visualize and problematic for the expert witness to explain. The forensic bisect approach is therefore a more favourable method in crime scene excavation, as it allows for clear and easy to understand testimony that will aid in the jury’s comprehension of the logical events surrounding the disposition of the body.

 

Presented in part at the 33rd Annual Meeting of the Canadian Association for Physical Anthropology (CAPA) Winnipeg, Manitoba. November 2-5, 2005 (podium).

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