Biomechanical allometry in hominoid thoracic vertebrae

Hernandez, Christopher J.; Loomis, D.A.; Cotter, Meghan; Schifle, A.L.; Anderson, Laurie C.; Elsmore, L.; Kunos, Charles; Latimer, Bruce

doi:10.1016/j.jhevol.2008.12.007

Cited by 23 publications

(32 citation statements)

References 39 publications

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“…The three main hypotheses proposed to explain the relatively gracile skeleton of contemporary humans include: (i) a reduction in physical activity because of increased sedentism and reliance on culture (1-6, 41), (ii) selection for systemic reduction of bone mass in modern humans (14,16), and (iii) attenuation of strain imposed upon trabecular bone because of larger joint surface areas (12,13). The morphological differences between the highly mobile foragers and relatively sedentary village agriculturalists clearly point to physical activity as a major determinant of bone mass in the hip joint.…”

Section: Discussionmentioning

confidence: 99%

“…Alternatively, it has been suggested that the low bone-volume fraction observed in human thoracic vertebrae and the first and second metatarsals are the result of systemic physiological differences between humans and apes (14,16). These studies do not suggest the mechanism or the function of this systemic gracility, but one potential explanation may be selection for increased tissue economy in hominins (5,(33)(34)(35).…”

Section: Significancementioning

confidence: 99%

“…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.…”

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confidence: 99%

“…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). The etiology of this relative gracility remains uncertain, and this uncertainty hinders the development of strategies for mitigating fracture risk and morbidity.…”

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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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Section: Discussionmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

mentioning

confidence: 99%

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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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“…Evidence indicates that vertebral body cross-sectional area scales isometrically (Shapiro and Simons, 2002) but no data exist regarding the scaling of strepsirhine trabecular bone volume fraction or any other architectural parameters. In contrast, data do exist for hominoids that indicate the cross-sectional area of the endplate, bone mass, and vertebral body length all increase isometrically with body mass in the eighth thoracic vertebral body whereas the trabecular bone volume fraction is invariant, trabecular thickness scales with negative allometry, and trabecular number scales with positive allometry as body mass increases Hernandez et al, 2009). …”

Section: Introductionmentioning

confidence: 98%

Lumbar Vertebral Body Bone Microstructural Scaling in Small to Medium‐Sized Strepsirhines

Fajardo

DeSilva

Manoharan

et al. 2013

The Anatomical Record

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Bone mass, architecture, and tissue mineral density contribute to bone strength. As body mass (BM) increases any one or combination of these properties could change to maintain structural integrity. To better understand the structural origins of vertebral fragility and gain insight into the mechanisms that govern bone adaptation, we conducted an integrative analysis of bone mass and microarchitecture in the last lumbar vertebral body from nine strepsirhine species, ranging in size from 42 g (Microcebus rufus) to 2,440 g (Eulemur macaco). Bone mass and architecture were assessed via mCT for the whole body and spherical volumes of interest (VOI). Allometric equations were estimated and compared with predictions for geometric scaling, assuming axial compression as the dominant loading regime. Bone mass, microarchitectural, and vertebral body geometric variables predominantly scaled isometrically. Among structural variables, the degree of anisotropy (Tb.DA) was the only parameter independent of BM and other trabecular architectural variables. Tb.DA was related to positional behavior. Orthograde primates had higher average Tb.DA (1.60) and more craniocaudally oriented trabeculae while lorisines had the lowest Tb.DA (1.25), as well as variably oriented trabeculae. Finally, lorisines had the highest ratio of trabecular bone volume to cortical shell volume ($3x) and while there appears to be flexibility in this ratio, the total bone volume (trabecular þ cortical) scales isometrically (BM 1.23 , r 2 ¼ 0.93) and appears tightly constrained. The common pattern of isometry in our measurements leaves open the question of how vertebral bodies in strepsirhine species compensate for increased BM. Anat Rec,

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Assessing patterns of variation in BV/TV in the calcaneus and C2 vertebra of Gorilla gorilla, Pan troglodytes, and populations of Homo sapiens from the Pleistocene and Holocene that differ in physical activity levels

Addison

Lieberman

2020

American J Phys Anthropol

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Objectives Because trabecular bone volume fraction (BV/TV) is influenced by variations in physical activity recent declines in BV/TV in humans are often attributed to modern sedentary lifestyles. This study tests the hypothesis that presumed variations in mechanical loading between groups can predict the observed BV/TV patterns in humans, chimpanzees and gorillas in two bones: the calcaneus which experiences high and well characterized impact forces, and the C2 vertebrae which experiences reduced locomotor forces. Materials and methods BV/TV and other structural variables were quantified from high‐resolution microCT scans in gorillas, chimpanzees, and four Homo sapiens populations: Pleistocene, semi‐sedentary Natufians; Holocene hunter‐gatherers from Point Hope, Alaska; Holocene nomadic pastoralists from medieval Europe; and modern, sedentary Americans. Results In the calcaneal tuberosity, Natufian BV/TV was 36, 46, and 46% greater than Alaskans (p = .02), Europeans (p = .005) and modern Americans (p = .002), respectively, but not significantly different from apes. BV/TV was not significantly different between modern Americans and Alaskans or Europeans. In the C2, Natufian BV/TV was 53 and 25% greater than in the Alaskan (p = .0001) and European (p = .048) populations. Discussion These results suggest that phenomena other than or in addition to variations in physical activity are needed to explain BV/TV patterns observed in H. sapiens, and point to a systemic decline in H. sapiens BV/TV after the Pleistocene.

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Biomechanical allometry in hominoid thoracic vertebrae

Cited by 23 publications

References 39 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

Lumbar Vertebral Body Bone Microstructural Scaling in Small to Medium‐Sized Strepsirhines

Assessing patterns of variation in BV/TV in the calcaneus and C2 vertebra of Gorilla gorilla, Pan troglodytes, and populations of Homo sapiens from the Pleistocene and Holocene that differ in physical activity levels

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