Smaller, weaker, and less stiff bones evolve from changes in subsistence strategy

Nowlan, Niamh C.; Jepsen, Karl J.; Morgan, Elise F.

doi:10.1007/s00198-010-1390-3

Cited by 16 publications

(14 citation statements)

References 33 publications

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“…These results strongly emphasize the importance of physical activity and exercise for bone health and the attenuation of age-related bone loss. trabecular bone | gracilization | human evolution | biomechanics | mobility C ompared with other hominoids and extinct hominin species, more recent humans possess relatively gracile postcranial skeletons (1)(2)(3)(4)(5)(6)(7)(8)(9). One of the consequences of this gracility in contemporary humans is an increased fracture risk associated with age-related bone loss and osteoporosis [hip fractures alone are projected to reach 6.26 million per year globally by 2050 (10)] (11)(12)(13)(14)(15).…”

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confidence: 99%

“…The most common explanation is that living populations are simply less physically active compared with extinct hominins or closely related contemporary wild apes (1)(2)(3)(4)(5)(6). This hypothesis suggests that a shift in subsistence patterns away from hunting and gathering, combined with an increased reliance on technology, led to reductions in overall physical activity levels and mobility in more recent hominins (cf.…”

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confidence: 99%

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Gracility of the modernHomo sapiensskeleton is the result of decreased biomechanical loading

Ryan

Shaw

2014

Proc. Natl. Acad. Sci. U.S.A.

159

195

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The postcranial skeleton of modern Homo sapiens is relatively gracile compared with other hominoids and earlier hominins. This gracility predisposes contemporary humans to osteoporosis and increased fracture risk. Explanations for this gracility include reduced levels of physical activity, the dissipation of load through enlarged joint surfaces, and selection for systemic physiological characteristics that differentiate modern humans from other primates. This study considered the skeletal remains of four behaviorally diverse recent human populations and a large sample of extant primates to assess variation in trabecular bone structure in the human hip joint. Proximal femur trabecular bone structure was quantified from microCT data for 229 individuals from 31 extant primate taxa and 59 individuals from four distinct archaeological human populations representing sedentary agriculturalists and mobile foragers. Analyses of mass-corrected trabecular bone variables reveal that the forager populations had significantly higher bone volume fraction, thicker trabeculae, and consequently lower relative bone surface area compared with the two agriculturalist groups. There were no significant differences between the agriculturalist and forager populations for trabecular spacing, number, or degree of anisotropy. These results reveal a correspondence between human behavior and bone structure in the proximal femur, indicating that more highly mobile human populations have trabecular bone structure similar to what would be expected for wild nonhuman primates of the same body mass. These results strongly emphasize the importance of physical activity and exercise for bone health and the attenuation of age-related bone loss. trabecular bone | gracilization | human evolution | biomechanics | mobility C ompared with other hominoids and extinct hominin species, more recent humans possess relatively gracile postcranial skeletons (1-9). One of the consequences of this gracility in contemporary humans is an increased fracture risk associated with age-related bone loss and osteoporosis [hip fractures alone are projected to reach 6.26 million per year globally by 2050 (10)] (11-15). The etiology of this relative gracility remains uncertain, and this uncertainty hinders the development of strategies for mitigating fracture risk and morbidity. The progressive gracilization of the Homo postcranial skeleton was originally detected in cortical bone structure (1, 2), but has now been demonstrated in the trabecular bone microstructure of joints (12,14,(16)(17)(18)(19), where osteoporotic fracture risk is highest (20). Most notably, in an analysis of thoracic vertebral bodies, Cotter et al. (12) found that young adult humans have significantly lower trabecular bone volume fraction (BV/TV) and thinner vertebral shells than similarly sized apes. Griffin et al. (16) also found significantly lower BV/TV in the human first and second metatarsal heads compared with hominoid primates. The results of these studies are corroborated by work on the hominoid...

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confidence: 99%

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confidence: 99%

Gracility of the modernHomo sapiensskeleton is the result of decreased biomechanical loading

Ryan

Shaw

2014

Proc. Natl. Acad. Sci. U.S.A.

159

195

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“…Cho et al () determined that there were significant differences in the cortical bone remodeling rates between different ancestry groups. Age, sex, and population differences in the rates and effectiveness of modeling and remodeling could influence bone geometry, and relative cortical area values (Fujita et al, ; Crenshaw et al, ; Högler et al, ; Mays, ; Leonard et al, ; Nowlan et al, ; Nelson et al, ; Ireland et al, ; Jepsen et al, in press; Rantalainen et al, ). The sample used in the present study is skewed towards older individuals of European ancestry, but potential differences in intraskeletal variability over a broader age range and ancestries may exist, and can only be examined with a more representative, larger, and broader sample.…”

Section: Discussionmentioning

confidence: 99%

Intraskeletal Variability of Relative Cortical Area in Humans

Stewart

Goliath

Stout

et al. 2015

The Anatomical Record

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Histomorphometric and cross-sectional geometric studies of bone have provided valuable information about age at death, behavioral and activity patterns, and pathological conditions for past and present human populations. While a considerable amount of exploratory and applied research has been completed using histomorphometric and cross-sectional geometric properties, the effects of intraskeletal variability on interpreting observed histomorphometric data have not been fully explored. The purpose of this study is to quantify intraskeletal variability in the relative cortical area of long bones and ribs from modern humans. To examine intraskeletal variability, cross-sections of the femur, tibia, fibula, humerus, radius, ulna, and rib when present, were examined within individuals from a cadaveric collection (N 5 34). Relative cortical area was compared within individuals using a repeated measurements General Linear Model, which shows significant differences between bones, particularly between the rib and the remaining long bones. Complementarily, correlations between bones' relative cortical area values suggest an important allometric component affecting this aspect of long bones, but not of the rib. This study highlights the magnitude of intraskeletal variability in relative cortical area in the human skeleton, and because the relative cortical area of any particular bone is affected by a series of confounding factors, extrapolation of relative cortical area values to infer load history for other skeletal elements can be misleading. Anat Rec, 298:1635Rec, 298: -1643Rec, 298: , 2015. V C 2015 Wiley Periodicals, Inc.

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“…Consistent with the results of others (32), women showed 10-11% less Ct.Ar relative to BW-Le compared to men (data not shown) which contributed in part to the functional disparity between sexes. This disparity in tibial stiffness relative to body size may help explain why women sustain approximately 5-times more stress fractures than men during gender-integrated military training regimens (33), and why fracture incidence is greater for elderly women compared to men (34). Prior work by others demonstrated that sex-differences in strength-related morphological parameters are not fully eliminated even after adjusting for body size (32,35).…”

Section: Figurementioning

confidence: 99%

“…Partial regression analyses were conducted to take the effects of age into consideration, showing that A) relative cortical area (RCA = Ct.Ar/Tt.Ar), B) Ct.TMD, C) Ma.BMD, and D) Ct.Th all correlate negatively with robustness. Superior Cortex: R 2 = 0.28, p<0.008 Inferior Cortex: R 2 = 0.04, p<0.34 Superior Cortex: R 2 = 0.28, p<0.008 Inferior Cortex: R 2 = 0.04, p<0.34 Superior Cortex: R 2 = 0.28, p<0.008 Superior Cortex: R 2 = 0.28, p<0.008 Inferior Cortex: R 2 = 0.04, p<0.34 Inferior Cortex: R 2 = 0.04, p<0 34. A validation study confirmed that A) Ct.TMD measured by pQCT correlated significantly with Ct.TMD measured by microCT, B) Ma.BMD measured by pQCT correlated significantly with Tb.TMD measured by microCT, and C) the overall TMD (cortical + trabecular) correlated significantly with ash content.…”

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confidence: 99%

Advancing Individualized Medicine by Understanding Phenotypic Integration Using the Human Skeleton as a Model System

Jepsen¹

2011

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Smaller, weaker, and less stiff bones evolve from changes in subsistence strategy

Cited by 16 publications

References 33 publications

Gracility of the modernHomo sapiensskeleton is the result of decreased biomechanical loading

Gracility of the modernHomo sapiensskeleton is the result of decreased biomechanical loading

Intraskeletal Variability of Relative Cortical Area in Humans

Advancing Individualized Medicine by Understanding Phenotypic Integration Using the Human Skeleton as a Model System

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