Publications by authors named "Laure Spake"

7 Publications

  • Page 1 of 1

Testing the cross-applicability of juvenile sex estimation from diaphyseal dimensions.

Forensic Sci Int 2021 Apr 20;321:110739. Epub 2021 Feb 20.

Department of Archaeology, Simon Fraser University, Burnaby, British Columbia, Canada. Electronic address:

Sex estimation is a crucial component of the biological profile. Stull et al. (2017) have proposed a promising juvenile sex estimation method using long bone measurements taken from a South African sample, providing relatively high classification accuracies and made easy to use via the KidStats web-based app. In this study, we test the models developed by Stull et al. (2017) on an external historic population from Lisbon, Portugal, in order to determine whether the models can be reliably applied to archeological and forensic populations outside of the original population sample. The study sample consisted of 102 individuals (45 females and 57 males) aged under 13 years at death from the Lisbon identified skeletal collection. Measurements from these individuals were used to test the flexible discriminant analysis (FDA) models given by Stull et al. (2017). Allocation accuracies were calculated for boys and girls and children over and under 2 years separately and combined. Our findings show that the models developed by Stull et al. (2017) yield poor accuracy when applied to our external population and thus can potentially be misapplied on archeological skeletal remains or forensic remains of unknown origin. A number of statistical issues may explain why models fail to be transportable or even generalizable, namely multicollinearity, model overfitting and overly optimist bootstrapped cross-validation rates. It is also likely that population differences in size and sexual size dimorphism also affected the applicability of the models. We emphasize the importance of externally validating prediction models, particularly if they are intended to be applied across populations. Our study addresses Stull and co-worker's request for further validation of the method on populations outside of South Africa, as the models cannot be confidently applied in the field until it has been externally validated.
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http://dx.doi.org/10.1016/j.forsciint.2021.110739DOI Listing
April 2021

Lack of biological mortality bias in the timing of dental formation in contemporary children: Implications for the study of past populations.

Am J Phys Anthropol 2021 Apr 4;174(4):646-660. Epub 2021 Jan 4.

Department of Archaeology and Centre for Forensic Research, Simon Fraser University, Burnaby, Canada.

Objectives: Biological mortality bias is the idea that individuals who perish (non-survivors) are biologically distinct from those who survive (survivors). If biological mortality bias is large enough, bioarchaeological studies of nonsurvivors (skeletal samples) cannot accurately represent the experiences of the survivors of that population. This effect is particularly problematic for the study of juvenile individuals, as growth is particularly sensitive to environmental insults. In this study, we test whether biological mortality bias exists in one dimension of growth, namely dental development.

Materials And Methods: Postmortem computed tomography scans of 206 children aged 12 years and younger at death were collected from two institutions in the United States and Australia. The sample was separated into children dying from natural causes as proxies for non-survivors and from accidental causes as proxies for survivors. Differences in the timing of dental development were assessed using sequential logistic regressions between dental formation stages and residual analysis of dental minus chronological age.

Results: No consistent delay in age of attainment of dental stages was documented between survivors and non-survivors. Delays between survivors and non-survivors in dental relative to chronological age were greatest for infants, and were greater for females than for males.

Discussion: Lack of biological mortality bias in dental development reinforces confidence in juvenile age estimates and therefore in skeletal growth profiles and growth studies. As dental development is known to be less environmentally sensitive than skeletal growth and development, further studies should examine biological mortality bias in long bone length.
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http://dx.doi.org/10.1002/ajpa.24218DOI Listing
April 2021

Severe skeletal lesions, osteopenia and growth deficit in a child with pulmonary tuberculosis (mid-20th century, Portugal).

Int J Paleopathol 2020 09 25;30:47-56. Epub 2020 May 25.

Department of Archaeology, Simon Fraser University, 8888 University Drive, Burnaby, Canada; Centro de Investigação em Antropologia e Saúde (CIAS), Department of Life Sciences, University of Coimbra, Calçada Martim De Freitas, 3000-456 Coimbra, Portugal. Electronic address:

Objective: This case-study provides a summary of skeletal lesions seen in a case of diagnosed juvenile pulmonary tuberculosis with extensive multifocal bony lesions.

Materials: Skeleton of a 9-year-old girl who died in the 1940s in Lisbon, Portugal. The remains of this individual are part of the Lisbon skeletal reference collection curated at the National Museum of Natural History and Science.

Methods: Lesions and paleopathological conditions were identified and documented through macroscopic, radiographic, computed tomographic, and mammographic analysis.

Results: The skeleton shows a variety of lytic lesions on the ribs and thoracic vertebrae including complete destruction of the bodies and fusion of the vertebral arches of four vertebrae, kyphosis, and scoliosis. Further pathological conditions were identified, including bone erosion, premature fusion of the left femoral head and greater trochanter, and abnormal size and shape changes to the lower limbs including loss of bone mass and stunting of the long bones.

Conclusions: Skeletal lesions are indicative of spondylitis, Pott's disease, and prolonged bedrest.

Significance: This case is one of the few examples of confirmed juvenile pulmonary tuberculosis with skeletal lesions prior to the antibiotic era. As such, it provides a reference for the skeletal abnormalities which may be observed in archaeological tuberculosis cases.

Limitations: Pulmonary tuberculosis was recorded as cause of death, however there is no documentation to know the length of illness period or the existence of any comorbidities.

Suggestions For Further Research: Consideration of multi-focal lesions is recommended when analyzing individuals with suspected tuberculosis.
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http://dx.doi.org/10.1016/j.ijpp.2020.03.002DOI Listing
September 2020

Indirect evidence for biological mortality bias in growth from two temporo-spatially distant samples of children.

Anthropol Anz 2019 Nov;76(5):379-390

Department of Archaeology and Centre for Forensic Research, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada.

Biological mortality bias in growth is a challenge to the analysis and understanding of past populations. In this analysis, we address two interrelated aspects of the bias: its potential magnitude in terms of linear growth and the association between height and survivorship. A contemporary sample of 292 children, whose recumbent length was measured at autopsy in Cuyahoga County, USA, was used to quantify the magnitude of mortality bias. Differences between survivors and non-survivors were quantified using t-tests and Cohen's d for effect size. While survivors were consistently taller than non-survivors, the difference did not become significant until after 7 years of age. A historical sample of 656 girls, whose height and weight were measured at admission to a tuberculosis sanitarium, was used to examine the relationship between height, weight, and survivorship. The survivors and non-survivors were compared using t-tests and Cohen's d, and odds of survival were modeled with logistic regression. Surviving girls were consistently taller and heavier than non-surviving girls. However, while taller girls were more somewhat more likely to survive, survivorship was more strongly associated with heavier weight at admission. Taken together, these results suggest that while mortality bias in growth may exist, it may not be large enough to impact interpretations of past population growth patterns. It should be noted that this is the case only if mortality bias does not vary significantly between different populations and if it does not significantly affect dental development.
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http://dx.doi.org/10.1127/anthranz/2019/0957DOI Listing
November 2019

Are we using the appropriate reference samples to develop juvenile age estimation methods based on bone size? An exploration of growth differences between average children and those who become victims of homicide.

Forensic Sci Int 2018 Jan 7;282:1-12. Epub 2017 Nov 7.

Department of Archaeology and Centre for Forensic Research, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada.

The population on which forensic juvenile skeletal age estimation methods are applied has not been critically considered. Previous research suggests that child victims of homicide tend to be from socioeconomically disadvantaged contexts, and that these contexts impair linear growth. This study investigates whether juvenile skeletal remains examined by forensic anthropologists are short for age compared to their normal healthy peers. Cadaver lengths were obtained from records of autopsies of 1256 individuals, aged birth to eighteen years at death, conducted between 2000 and 2015 in Australia, New Zealand, and the U.S. Growth status of the forensic population, represented by homicide victims, and general population, represented by accident victims, were compared using height for age Z-scores and independent sample t-tests. Cadaver lengths of the accident victims were compared to growth references using one sample t-tests to evaluate whether accident victims reflect the general population. Homicide victims are shorter for age than accident victims in samples from the U.S., but not in Australia and New Zealand. Accident victims are more representative of the general population in Australia and New Zealand. Different results in Australia and New Zealand as opposed to the U.S. may be linked to socioeconomic inequality. These results suggest that physical anthropologists should critically select reference samples when devising forensic juvenile skeletal age estimation methods. Children examined in forensic investigations may be short for age, and thus methods developed on normal healthy children may yield inaccurate results. A healthy reference population may not necessarily constitute an appropriate growth comparison for the forensic anthropology population.
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http://dx.doi.org/10.1016/j.forsciint.2017.10.041DOI Listing
January 2018

Age estimation of immature human skeletal remains from the dimensions of the girdle bones in the postnatal period.

Am J Phys Anthropol 2017 08 24;163(4):772-783. Epub 2017 May 24.

Human Origins Group, Department of Earth Sciences, The Natural History Museum, London, SW7 5BD, United Kingdom.

Objectives: This study provides classical calibration regression formulae for age estimation from the dimensions of unfused shoulder and pelvic girdle bones.

Materials And Methods: Age estimation models were derived from a sample of 160 known age and sex individuals (63 females and 97 males) aged birth to 12 years, selected from Portuguese and English skeletal collections. The sample was divided into two age groups at the age of 2 years, and formulae were obtained for the sexes separately and combined.

Results: Measurements of the pelvis provide more precise age estimates than the shoulder. In the younger age group, the height and width of the ilium, and the height of the glenoid yield the most precise age estimates. In the older age group, the length of the clavicle provides the most precise estimates, followed by measurements of the pubis and ischium.

Discussion: In the younger individuals (<2 years), age estimates based on measurements of the pelvic girdle seem to be as or more precise than those based on the length of long bones. In older individuals (≥2 years), estimates based on the measurements of the girdles are less precise than those based on the length of long bones. These age estimation formulae may be useful for fragmentary and incomplete material in archaeological and forensic contexts. The formulae are suitable for a variety of archeological populations living under adverse conditions. These conditions are similar to some "developing" countries, and hence the formulae may also be applicable to modern forensic remains from such environments.
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http://dx.doi.org/10.1002/ajpa.23248DOI Listing
August 2017

A Reappraisal of Developing Permanent Tooth Length as an Estimate of Age in Human Immature Skeletal Remains.

J Forensic Sci 2016 09 20;61(5):1180-9. Epub 2016 Jun 20.

Institute of Dentistry, Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Turner Street, London, E1 2AD, U.K.

This study expands on existing juvenile age prediction models from tooth length by increasing sample size and using classical calibration. A sample of 178 individuals from two European known sex and age skeletal samples was used to calculate prediction formulae for each tooth for each sex separately and combined. Prediction errors, residuals, and percentage of individuals whose real age fell within the 95% prediction interval were calculated. An ANCOVA was used to test sex and sample differences. Tooth length for age does not differ between the samples except for the canine and second premolar, and no statistically significant sex differences were detected. The least prediction error was found in the incisors and the first molar, and the highest prediction error was found in the third molar. Age prediction formulae provided here can be easily used in a variety of contexts where tooth length is measured from any isolated tooth.
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http://dx.doi.org/10.1111/1556-4029.13120DOI Listing
September 2016