Papers by L. Elizabeth Doyle
International Journal of Palaeopathology, Dec 1, 2014
An obstetric dilemma may have been a persistent characteristic of human evolution, in which the b... more An obstetric dilemma may have been a persistent characteristic of human evolution, in which the bipedal female's pelvis is barely large enough to accommodate the birth of a large-brained neonate. Evidence in the archaeological record for mortality risk associated with childbirth is rare, especially among highly mobile, immediate return hunter-gatherer populations. This research explores the idea that if excess mortality is associated with first pregnancy, females will outnumber males among young adult skeletons. The sample is of 246 skeletons (119 males, 127 females) representing Later Stone Age (LSA) foragers of the South African Cape. Young adults are distinguished through incomplete maturation of the medial clavicle, iliac crest and vertebral bodies. With 26 women and 14 men in the young category, a higher mortality risk for women is suggested, particularly in the Southern Cape region. Body size does not distinguish mortality groups; there is evidence of a dietary protein difference between young and older women from the Southern Cape. Possible increased mortality associated with first parturition may have been linked to morphological or energetic challenges, or a combination of both. Exploration of the sex ratio among young adult skeletons provides a tool for exploring the antiquity of an important evolutionary factor.
American Journal of Human Biology, May 20, 2011
Objectives:
This study seeks to understand the interaction of cortical bone strength and mass wi... more Objectives:
This study seeks to understand the interaction of cortical bone strength and mass within individuals and across age-groups in male and female adults from a relatively active, long-lived nineteenth-century Euro-Canadian population.
Methods:
Strength and relative cortical area are measured in paired femora (weight-bearing elements) and metacarpals (manipulative elements) from 139 adults (M = 82; F = 52). Sex and age patterns are tested using linear multiple regression and analysis of covariance. Intra-individual divergence between femora and metacarpals is quantified using the Pearson residual from regression of femur on metacarpal values. Association of residuals with age is tested with curve estimation, factorial analysis of variance and X2 tests.
Results:
Strength is maintained but cortical mass declines with age. In females, the slope of cortical mass against age is steeper in the metacarpal than in the femur. However, the degree of divergence between femur and metacarpal within individuals does not increase clearly with age.
Conclusions:
Age change in bone strength is systemically controlled and homeostatic, but change in bone mass may vary with limb-specific mechanical environment, particularly in females. However, the distribution of within-individual divergence between femur and metacarpal values suggests that idiosyncratic factors, rather than age, have the strongest influence on intraskeletal divergence. Attempts to reconstruct skeletal ageing in past populations may benefit from an approach that models whole-bone integrity, rather than bone mass alone, and that represents age-related variation in both weight-bearing and non weight-bearing sites.
Conference Presentations by L. Elizabeth Doyle
The terminal Later Stone Age on the southwestern African Cape features a short period of intense ... more The terminal Later Stone Age on the southwestern African Cape features a short period of intense land use, more limited home ranges, and occasional lethal violence. Mean body sizes are smallest during this period, suggesting that some foragers experienced statural stunting. This study compares temporal variation in the size of the neural canal (NC) with that in body size (N=105; M=56; F=49).
Z-transformed mediolateral (ML) and anteroposterior (AP) NC diameters, maximum femur lengths (FXL) and femur head diameters (FXH) are regressed on radiocarbon date using polynomial regression. Mean sizes are compared before, during, and after the intensification period with one-way ANOVA.
FXL, FXH, and ML-NC exhibit similar quadratic curves with a nadir between 2000 and 3000bp. Mean values are greatest after the intensification period (p<0.05). However, regression models are markedly stronger for FXL and FXH than for NC (FXL Beta1=-1.60, Beta2=1.43, R2=0.20, p<0.05; FXH Beta1=-1.64, Beta 2=1.49, R2=0.20, p<0.05; NC-ML Beta 1=-0.83, Beta2=0.68, R2=0.06, p<0.05).
The attenuated change in NC size, in contrast with the apparent decrease in body size suggests that the intensification period did not affect early childhood growth among those who survived to adulthood. The terminal Holocene increase in average size coincides with a possible population contraction and with the earliest regional appearance of livestock. Subsistence and demographic changes, accompanied by the shift in average body and neuroskeletal size, may signal that social conditions were shifting away from an earlier Holocene status quo.
This research was financially supported by the Social Sciences and Humanities Research Council of Canada.
Epidemiological evidence indicates that osteoarthritis (OA) is influenced by systemic biology. So... more Epidemiological evidence indicates that osteoarthritis (OA) is influenced by systemic biology. Some authors suggest that a “bone-forming” phenotype, characterised by rugose and
ossified entheses, is a factor in susceptibility to OA. One study links ossified entheses (bone- forming, or BF) with subchondral eburnation and osteophyte in archaeological skeletons classified as older or younger than 45 years (Rogers et al., 2004); however, skeletal age estimates are imprecise, making the independence of the association uncertain. Here, the BF-OA relationship is tested and other potential systemic associations explored in a sample of males with known biographical data. BF and four features associated with bony OA (osteophyte, eburnation, pitting, and superficial new bone) are ordinally quantified in 50 Euro-Canadian males aged 17 to
90. Associations with age at death, body size, and cause of death are tested with odds ratios, partial correlation, and logistic regression. Results affirm the effect of age on BF and all OA variables, even in individuals aged 50 and over (n=31). BF score correlates with the proportion of joints affected by pitting when age is controlled, and with femur midshaft circumference and osteophyte severity when age and femur length are controlled. Fatal cardiovascular disease is implicated in age-controlled femur circumference. These results are consistent with the hypothesis that joint degeneration correlates with extra-articular biological processes, and suggest that osteology may offer future insight into the skeleton’s role in systemic degenerative disease.
This project was supported by the University of Toronto School of Graduate Studies and by the Canadian Social Sciences and Humanities Research Council.
This is a study of two cases of cranial injury from the southern West Coast, with the aim of iden... more This is a study of two cases of cranial injury from the southern West Coast, with the aim of identifying possible causes and situating them in the context of mid-Holocene population dynamics in the Western Cape. The Later Stone Age of southern Africa is characterised by small-scale, mobile foraging groups with ancestral ties to living Khoe-San speakers. To date, over 360 individuals have been documented, dating from 140 to 10,860 uncalibrated years before present (bp). Evidence of interpersonal violence is rare, with the exception of 10 cases of what appear to be deliberate injuries: 7 perimortem cases (all adult females or juveniles) and 3 exhibiting healing (all adult males). These cases are surprisingly clustered in both space and time: all perimortem cases (from four sites) are from the southern West Coast, and all available dates fall between 2220 and 2800bp. These dates coincide with a period of population growth throughout the Cape. On the West Coast in particular, intense resource harvesting, the appearance of stunted adults, and isotopic evidence of territorial partitioning suggest a scenario of prevalent tension during this time. Both new cases date to 2300 and 2240bp. The first is a relatively small, older male with a linear gash on the right parietal boss. The gash has a fusiform outline and v-shaped profile, suggesting an impact from an edged object. Remodelling is incomplete, but sufficient healing had taken place to infer an interval of months to years before his death. The second case, a young female, has two unhealed depressed fractures in the the left parietal. The smaller of the two resembles a clean puncture, while the larger is roughly ovoid in outline, suggesting a blow with a pointed object of round cross-section. Both individuals bear traumas consistent with deliberate injury, though from different instruments. Based on descriptions of other cases, both are consistent with other West Coast instances of deliberate, perimortem injury from the same period. Although positive evidence is still elusive, these individuals add two datapoints in support of the narrative of a tense period linked to increased population density on the Cape West Coast.
Resilience and adaptation in past populations are increasingly studied through the lens of childh... more Resilience and adaptation in past populations are increasingly studied through the lens of childhood stress. Neural canal size (NC) in the thoracic and lumbar spine shows potential as a marker of stress because it reaches adult size relatively early in development and is therefore
less amenable to catch-up growth.
Research has linked smaller canals to earlier adult
mortality, but confounding by socioeconomic factors is a potential concern. This study tests the hypothesis that a smaller neural canal is associated with lower adulthood
survival in Later Stone Age KhoeSan foragers, a population with little evidence of social inequality.
Anteroposterior (AP) and mediolateral (ML) diameters were measured at T1, T6, L1, and L5 (n=143). Preservation varied, so missing values were imputed in 5 iterative datasets, giving a
final n=105 (F=49; M=56). Femur length and head diameter served as proxies for body size. Individuals were categorized as “young” (<35 years) or “mature” (35≤ years) based on conventional indicators. Logistic regression was used to test the hypothesis.
An increase in ML equal to 1 standard deviation was associated with, on average, 60% greater odds of surviving to mature adulthood (p<0.05), while AP diameter showed no effect. The effect was strong in females, but weak in males. Body size was not a significant confounder. Although confounding by heterogeneous environmental stressors cannot be ruled out, these results suggest that childhood outcomes and adulthood survival are linked even when social stratification is minimal. Early-life growth effects may be a long-standing feature of human life history.
This work has been supported by the Canadian
Social Sciences and Humanities Research
Council
Thesis by L. Elizabeth Doyle
Harsh conditions during development may alter the human adult phenotype in ways that affect vulne... more Harsh conditions during development may alter the human adult phenotype in ways that affect vulnerability to disease and death. This study’s objectives are A) to explore the utility of neural canal size and appendicular osteoarthritis as prospective indicators of developmental stress; B) to test for developmental stress effects in a foraging population with no significant socioeconomic stratification; and C) to explore temporal variation in neuroskeletal size and joint degeneration. The study sample consists of 143 Later Stone Age foragers (M=75, F=64, I=4) from the Cape Floristic Region of southern Africa. 135 cases have radiocarbon dates between 9100 and 560 uncalibrated years BP. Osteoarthritis was quantified with an ordinal scoring procedure. Relationships among radiocarbon date, measures of body and neural canal size, OA, and age at death were explored using logistic and ordinary least squares regression, independence tests, and means contrasts. Age, sex, and body size were controlled where appropriate. A positive relationship is observed between age at death and both body size and ML NC diameter, but reaches statistical significance only in the latter case (OR=1.74, 95% CI=1.08–2.82). The effect is detected in both sexes but odds ratios are greater and p values smaller in females (Male OR=1.50, 95% CI=0.82–2.73; Female OR=2.14, 95% CI=1.02–4.50). Age at death is the only significant predictor for both presence and severity of osteoarthritis. No significant relationship is observed between age and anteroposterior diameter. Average mediolateral diameter of the neural canal declines between 3000–2000BP and increases slightly afterwards (β 1 = −0.83, β 2 = 0.68, adjusted R 2 = 0.06, SEE=0.99). This quadratic curve is consistent with published accounts of temporal change in average body size. No temporal pattern is identified in osteoarthritis.
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Papers by L. Elizabeth Doyle
This study seeks to understand the interaction of cortical bone strength and mass within individuals and across age-groups in male and female adults from a relatively active, long-lived nineteenth-century Euro-Canadian population.
Methods:
Strength and relative cortical area are measured in paired femora (weight-bearing elements) and metacarpals (manipulative elements) from 139 adults (M = 82; F = 52). Sex and age patterns are tested using linear multiple regression and analysis of covariance. Intra-individual divergence between femora and metacarpals is quantified using the Pearson residual from regression of femur on metacarpal values. Association of residuals with age is tested with curve estimation, factorial analysis of variance and X2 tests.
Results:
Strength is maintained but cortical mass declines with age. In females, the slope of cortical mass against age is steeper in the metacarpal than in the femur. However, the degree of divergence between femur and metacarpal within individuals does not increase clearly with age.
Conclusions:
Age change in bone strength is systemically controlled and homeostatic, but change in bone mass may vary with limb-specific mechanical environment, particularly in females. However, the distribution of within-individual divergence between femur and metacarpal values suggests that idiosyncratic factors, rather than age, have the strongest influence on intraskeletal divergence. Attempts to reconstruct skeletal ageing in past populations may benefit from an approach that models whole-bone integrity, rather than bone mass alone, and that represents age-related variation in both weight-bearing and non weight-bearing sites.
Conference Presentations by L. Elizabeth Doyle
Z-transformed mediolateral (ML) and anteroposterior (AP) NC diameters, maximum femur lengths (FXL) and femur head diameters (FXH) are regressed on radiocarbon date using polynomial regression. Mean sizes are compared before, during, and after the intensification period with one-way ANOVA.
FXL, FXH, and ML-NC exhibit similar quadratic curves with a nadir between 2000 and 3000bp. Mean values are greatest after the intensification period (p<0.05). However, regression models are markedly stronger for FXL and FXH than for NC (FXL Beta1=-1.60, Beta2=1.43, R2=0.20, p<0.05; FXH Beta1=-1.64, Beta 2=1.49, R2=0.20, p<0.05; NC-ML Beta 1=-0.83, Beta2=0.68, R2=0.06, p<0.05).
The attenuated change in NC size, in contrast with the apparent decrease in body size suggests that the intensification period did not affect early childhood growth among those who survived to adulthood. The terminal Holocene increase in average size coincides with a possible population contraction and with the earliest regional appearance of livestock. Subsistence and demographic changes, accompanied by the shift in average body and neuroskeletal size, may signal that social conditions were shifting away from an earlier Holocene status quo.
This research was financially supported by the Social Sciences and Humanities Research Council of Canada.
ossified entheses, is a factor in susceptibility to OA. One study links ossified entheses (bone- forming, or BF) with subchondral eburnation and osteophyte in archaeological skeletons classified as older or younger than 45 years (Rogers et al., 2004); however, skeletal age estimates are imprecise, making the independence of the association uncertain. Here, the BF-OA relationship is tested and other potential systemic associations explored in a sample of males with known biographical data. BF and four features associated with bony OA (osteophyte, eburnation, pitting, and superficial new bone) are ordinally quantified in 50 Euro-Canadian males aged 17 to
90. Associations with age at death, body size, and cause of death are tested with odds ratios, partial correlation, and logistic regression. Results affirm the effect of age on BF and all OA variables, even in individuals aged 50 and over (n=31). BF score correlates with the proportion of joints affected by pitting when age is controlled, and with femur midshaft circumference and osteophyte severity when age and femur length are controlled. Fatal cardiovascular disease is implicated in age-controlled femur circumference. These results are consistent with the hypothesis that joint degeneration correlates with extra-articular biological processes, and suggest that osteology may offer future insight into the skeleton’s role in systemic degenerative disease.
This project was supported by the University of Toronto School of Graduate Studies and by the Canadian Social Sciences and Humanities Research Council.
less amenable to catch-up growth.
Research has linked smaller canals to earlier adult
mortality, but confounding by socioeconomic factors is a potential concern. This study tests the hypothesis that a smaller neural canal is associated with lower adulthood
survival in Later Stone Age KhoeSan foragers, a population with little evidence of social inequality.
Anteroposterior (AP) and mediolateral (ML) diameters were measured at T1, T6, L1, and L5 (n=143). Preservation varied, so missing values were imputed in 5 iterative datasets, giving a
final n=105 (F=49; M=56). Femur length and head diameter served as proxies for body size. Individuals were categorized as “young” (<35 years) or “mature” (35≤ years) based on conventional indicators. Logistic regression was used to test the hypothesis.
An increase in ML equal to 1 standard deviation was associated with, on average, 60% greater odds of surviving to mature adulthood (p<0.05), while AP diameter showed no effect. The effect was strong in females, but weak in males. Body size was not a significant confounder. Although confounding by heterogeneous environmental stressors cannot be ruled out, these results suggest that childhood outcomes and adulthood survival are linked even when social stratification is minimal. Early-life growth effects may be a long-standing feature of human life history.
This work has been supported by the Canadian
Social Sciences and Humanities Research
Council
Thesis by L. Elizabeth Doyle
This study seeks to understand the interaction of cortical bone strength and mass within individuals and across age-groups in male and female adults from a relatively active, long-lived nineteenth-century Euro-Canadian population.
Methods:
Strength and relative cortical area are measured in paired femora (weight-bearing elements) and metacarpals (manipulative elements) from 139 adults (M = 82; F = 52). Sex and age patterns are tested using linear multiple regression and analysis of covariance. Intra-individual divergence between femora and metacarpals is quantified using the Pearson residual from regression of femur on metacarpal values. Association of residuals with age is tested with curve estimation, factorial analysis of variance and X2 tests.
Results:
Strength is maintained but cortical mass declines with age. In females, the slope of cortical mass against age is steeper in the metacarpal than in the femur. However, the degree of divergence between femur and metacarpal within individuals does not increase clearly with age.
Conclusions:
Age change in bone strength is systemically controlled and homeostatic, but change in bone mass may vary with limb-specific mechanical environment, particularly in females. However, the distribution of within-individual divergence between femur and metacarpal values suggests that idiosyncratic factors, rather than age, have the strongest influence on intraskeletal divergence. Attempts to reconstruct skeletal ageing in past populations may benefit from an approach that models whole-bone integrity, rather than bone mass alone, and that represents age-related variation in both weight-bearing and non weight-bearing sites.
Z-transformed mediolateral (ML) and anteroposterior (AP) NC diameters, maximum femur lengths (FXL) and femur head diameters (FXH) are regressed on radiocarbon date using polynomial regression. Mean sizes are compared before, during, and after the intensification period with one-way ANOVA.
FXL, FXH, and ML-NC exhibit similar quadratic curves with a nadir between 2000 and 3000bp. Mean values are greatest after the intensification period (p<0.05). However, regression models are markedly stronger for FXL and FXH than for NC (FXL Beta1=-1.60, Beta2=1.43, R2=0.20, p<0.05; FXH Beta1=-1.64, Beta 2=1.49, R2=0.20, p<0.05; NC-ML Beta 1=-0.83, Beta2=0.68, R2=0.06, p<0.05).
The attenuated change in NC size, in contrast with the apparent decrease in body size suggests that the intensification period did not affect early childhood growth among those who survived to adulthood. The terminal Holocene increase in average size coincides with a possible population contraction and with the earliest regional appearance of livestock. Subsistence and demographic changes, accompanied by the shift in average body and neuroskeletal size, may signal that social conditions were shifting away from an earlier Holocene status quo.
This research was financially supported by the Social Sciences and Humanities Research Council of Canada.
ossified entheses, is a factor in susceptibility to OA. One study links ossified entheses (bone- forming, or BF) with subchondral eburnation and osteophyte in archaeological skeletons classified as older or younger than 45 years (Rogers et al., 2004); however, skeletal age estimates are imprecise, making the independence of the association uncertain. Here, the BF-OA relationship is tested and other potential systemic associations explored in a sample of males with known biographical data. BF and four features associated with bony OA (osteophyte, eburnation, pitting, and superficial new bone) are ordinally quantified in 50 Euro-Canadian males aged 17 to
90. Associations with age at death, body size, and cause of death are tested with odds ratios, partial correlation, and logistic regression. Results affirm the effect of age on BF and all OA variables, even in individuals aged 50 and over (n=31). BF score correlates with the proportion of joints affected by pitting when age is controlled, and with femur midshaft circumference and osteophyte severity when age and femur length are controlled. Fatal cardiovascular disease is implicated in age-controlled femur circumference. These results are consistent with the hypothesis that joint degeneration correlates with extra-articular biological processes, and suggest that osteology may offer future insight into the skeleton’s role in systemic degenerative disease.
This project was supported by the University of Toronto School of Graduate Studies and by the Canadian Social Sciences and Humanities Research Council.
less amenable to catch-up growth.
Research has linked smaller canals to earlier adult
mortality, but confounding by socioeconomic factors is a potential concern. This study tests the hypothesis that a smaller neural canal is associated with lower adulthood
survival in Later Stone Age KhoeSan foragers, a population with little evidence of social inequality.
Anteroposterior (AP) and mediolateral (ML) diameters were measured at T1, T6, L1, and L5 (n=143). Preservation varied, so missing values were imputed in 5 iterative datasets, giving a
final n=105 (F=49; M=56). Femur length and head diameter served as proxies for body size. Individuals were categorized as “young” (<35 years) or “mature” (35≤ years) based on conventional indicators. Logistic regression was used to test the hypothesis.
An increase in ML equal to 1 standard deviation was associated with, on average, 60% greater odds of surviving to mature adulthood (p<0.05), while AP diameter showed no effect. The effect was strong in females, but weak in males. Body size was not a significant confounder. Although confounding by heterogeneous environmental stressors cannot be ruled out, these results suggest that childhood outcomes and adulthood survival are linked even when social stratification is minimal. Early-life growth effects may be a long-standing feature of human life history.
This work has been supported by the Canadian
Social Sciences and Humanities Research
Council