African apes and the evolutionary history of orthogrady and bipedalism

ObjectivesLow‐energy vertebral fractures are a common health concern, especially in elderly people. Interestingly, African apes do not seem to experience as many vertebral fractures and the low‐energy ones are even rarer. One potential explanation for this difference is the lower bone density in humans. Yet, only limited research has been done on the vertebral bone density of the great apes and these have mainly included only single vertebrae. Hence the study aim is to expand our understanding of the vertebral microstructure of African apes in multiple spinal segments.MaterialsBone density in the vertebral body of C7, T12, and L3 was measured from 32 Pan troglodytes and 26 Gorilla gorilla using peripheral quantitative computed tomography (pQCT).ResultsThere was a clear difference between the three individual vertebrae and consequently the spinal segments in terms of trabecular density and cortical density and thickness. The variation of these bone parameters between the vertebrae differed between the apes but was also different from those reported for humans. The chimpanzees were observed to have overall higher trabecular density, but gorillas had higher cortical density and thickness. Cortical thickness had a relatively strong association with the vertebral size.DiscussionDespite the similarity in locomotion and posture, the results show slight differences in the bone parameters and their variation between spinal segments in African apes. This variation also differs from humans and appears to indicate a complex influence of locomotion, posture, and body size on the different spinal segments.

Section: Segmental Differences and Locomotionmentioning

confidence: 99%

Differences in vertebral bone density between African apes

Korpinen

2024

“…The purpose of this study is to explore the morphological and morpho‐structural integration within the femur‐pelvis module and their relation to the positional repertoire (i.e., posture and locomotion) in primates. To do so, we use three models of primates that exhibit distinct positional repertoires (Table 1): (1) humans ( Homo sapiens ) of which the positional repertoire is almost restricted to bipedalism with a fully orthograde posture in adults (but see Venkataraman et al, 2013); (2) olive baboons ( Papio anubis ) considered as mainly terrestrial and quadrupedal with a pronograde posture in adults (Druelle, Aerts, & Berillon, 2017; Hunt, 2016; Rose, 1977); (3) chimpanzees ( Pan troglodytes ) and bonobos ( P. paniscus ) that exhibit a wider positional repertoire (i.e., more diversity) than humans and baboons, including knuckle walking, arboreal climbing and suspensory behaviors, and both orthograde and pronograde posture (Doran, 1992; Hunt, 1992; Williams et al, 2023). For each three models, we explore potential patterns of integration at three levels: the magnitude of morphological integration between the external morphology of the pelvis and that of the femur.…”

Section: Introductionmentioning

confidence: 99%

New insights into patterns of integration in the femur and pelvis among catarrhines

Cosnefroy,

Berillon,

Gilissen

et al. 2024

ObjectivesIntegration reflects the level of coordinated variation of the phenotype. The integration of postcranial elements can be studied from a functional perspective, especially with regards to locomotion. This study investigates the link between locomotion, femoral structural properties, and femur‐pelvis complex morphology.Materials and MethodsWe measured (1) morphological integration between femoral and pelvic morphologies using geometric morphometrics, and (2) covariation between femoral/pelvic morphologies and femoral diaphyseal cross‐sectional properties, which we defined as morpho‐structural integration. Morphological and morpho‐structural integration patterns were measured among humans (n = 19), chimpanzees and bonobos (n = 16), and baboons (n = 14), whose locomotion are distinct.ResultsBaboons show the highest magnitude of morphological integration and the lowest of morpho‐structural integration. Chimpanzees and bonobos show intermediate magnitude of morphological and morpho‐structural integration. Yet, body size seems to have a considerable influence on both integration patterns, limiting the interpretations. Finally, humans present the lowest morphological integration and the highest morpho‐structural integration between femoral morphology and structural properties but not between pelvic morphology and femur.DiscussionMorphological and morpho‐structural integration depict distinct strategies among the samples. A strong morphological integration among baboon's femur‐pelvis module might highlight evidence for long‐term adaptation to quadrupedalism. In humans, it is likely that distinct selective pressures associated with the respective function of the pelvis and the femur tend to decrease morphological integration. Conversely, high mechanical loading on the hindlimbs during bipedal locomotion might result in specific combination of structural and morphological features within the femur.

“…Primates exhibit an important intertaxic locomotor diversity, which is reflected not only in the variable anatomy of their limbs but also in some particularities in the rest of their skeleton (Almécija et al, 2021; Fleagle, 2013; Williams et al, 2023). Given that the ribcage and the lumbar spine are the nexus between the shoulder and pelvic girdles, their configuration is highly related to the mode of locomotion in this group (Fleagle & Lieberman, 2021).…”

Section: Introductionmentioning

confidence: 99%

Covariation between the shape and mineralized tissues of the rib cross section in Homo sapiens, Pan troglodytes and Sts 14

López‐Rey,

Cambra‐Moo,

González Martín

et al. 2023

Self Cite

ObjectivesStudying rib torsion is crucial for understanding the evolution of the hominid ribcage. Interestingly, there are variables of the rib cross section that could be associated with rib torsion and, consequently, with the morphology of the thorax. The aim of this research is to conduct a comparative study of the shape and mineralized tissues of the rib cross section in different hominids to test for significant differences and, if possible, associate them to different thoracic morphotypes.Materials and MethodsThe sample consists of the rib cross sections at the midshaft taken from 10 Homo sapiens and 10 Pan troglodytes adult individuals, as well as from A. africanus Sts 14. The shape of these rib cross sections was quantified using geometric morphometrics, while the mineralized tissues were evaluated using the compartmentalization index. Subsequently, covariation between both parameters was tested by a Spearman's ρ test, a permutation test and a linear regression.ResultsGenerally, P. troglodytes individuals exhibit rib cross sections that are rounder and more mineralized compared to those of H. sapiens. However, the covariation between both parameters was only observed in typical ribs (levels 3–10). Although covariation was not found in the rib cross sections of Sts 14, their parameters are closer to P. troglodytes.DiscussionOn the one hand, the differences observed in the rib cross sections between H. sapiens and P. troglodytes might be related to different degrees of rib torsion and, consequently, to different thoracic 3D configurations. These findings can be functionally explained by considering their distinct modes of breathing and locomotion. On the other hand, although the rib cross sections belonging to Sts 14 are more similar to those of P. troglodytes, previous publications determined that their overall morphology is closer to modern humans. This discrepancy could reflect a diversity of post‐cranial adaptations in Australopithecus.