scholarly journals Spondylolysis and spinal adaptations for bipedalism

2020 ◽  
Vol 2020 (1) ◽  
pp. 35-44
Author(s):  
Kimberly A Plomp ◽  
Keith Dobney ◽  
Mark Collard
Keyword(s):  
Fatigue Fracture ◽  
Evolutionary History ◽  
Homo Sapiens ◽  
Lumbar Vertebrae ◽  
Great Ape ◽  
Shape Variation ◽  
3D Data ◽  
Schmorl’S Nodes ◽  
Vertebral Shape ◽  
Range Of Variation

Abstract Background and objectives The study reported here focused on the aetiology of spondylolysis, a vertebral pathology usually caused by a fatigue fracture. The goal was to test the Overshoot Hypothesis, which proposes that people develop spondylolysis because their vertebral shape is at the highly derived end of the range of variation within Homo sapiens. Methodology We recorded 3D data on the final lumbar vertebrae of H. sapiens and three great ape species, and performed three analyses. First, we compared H. sapiens vertebrae with and without spondylolysis. Second, we compared H. sapiens vertebrae with and without spondylolysis to great ape vertebrae. Lastly, we compared H. sapiens vertebrae with and without spondylolysis to great ape vertebrae and to vertebrae of H. sapiens with Schmorl’s nodes, which previous studies have shown tend to be located at the ancestral end of the range of H. sapiens shape variation. Results We found that H. sapiens vertebrae with spondylolysis are significantly different in shape from healthy H. sapiens vertebrae. We also found that H. sapiens vertebrae with spondylolysis are more distant from great ape vertebrae than are healthy H. sapiens vertebrae. Lastly, we found that H. sapiens vertebrae with spondylolysis are at the opposite end of the range of shape variation than vertebrae with Schmorl’s nodes. Conclusions Our findings indicate that H. sapiens vertebrae with spondylolysis tend to exhibit highly derived traits and therefore support the Overshoot Hypothesis. Spondylolysis, it appears, is linked to our lineage’s evolutionary history, especially its shift from quadrupedalism to bipedalism. Lay summary: Spondylolysis is a relatively common vertebral pathology usually caused by a fatigue fracture. There is reason to think that it might be connected with our lineage’s evolutionary shift from walking on all fours to walking on two legs. We tested this idea by comparing human vertebrae with and without spondylolysis to the vertebrae of great apes. Our results support the hypothesis. They suggest that people who experience spondylolysis have vertebrae with what are effectively exaggerated adaptations for bipedalism.

scholarly journals 3D shape analyses of extant primate and fossil hominin vertebrae support the ancestral shape hypothesis for intervertebral disc herniation

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Kimberly A. Plomp ◽  
Keith Dobney ◽  
Darlene A. Weston ◽  
Una Strand Viðarsdóttir ◽  
Mark Collard
Keyword(s):  
Intervertebral Disc ◽  
Disc Herniation ◽  
Evolutionary Biology ◽  
Homo Sapiens ◽  
Lumbar Vertebrae ◽  
Intervertebral Disc Herniation ◽  
Shape Variation ◽  
Healthy Humans ◽  
2D Data ◽  
Vertebral Shape

Abstract Background Recently we proposed an evolutionary explanation for a spinal pathology that afflicts many people, intervertebral disc herniation (Plomp et al. [2015] BMC Evolutionary Biology 15, 68). Using 2D data, we found that the bodies and pedicles of lower vertebrae of pathological humans were more similar in shape to those of chimpanzees than were those of healthy humans. Based on this, we hypothesized that some individuals are more prone to intervertebral disc herniation because their vertebrae exhibit ancestral traits and therefore are less well adapted for the stresses associated with bipedalism. Here, we report a study in which we tested this “Ancestral Shape Hypothesis” with 3D data from the last two thoracic and first lumbar vertebrae of pathological Homo sapiens, healthy H. sapiens, Pan troglodytes, and several extinct hominins. Results We found that the pathological and healthy H. sapiens vertebrae differed significantly in shape, and that the pathological H. sapiens vertebrae were closer in shape to the P. troglodytes vertebrae than were the healthy H. sapiens vertebrae. Additionally, we found that the pathological human vertebrae were generally more similar in shape to the vertebrae of the extinct hominins than were the healthy H. sapiens vertebrae. These results are consistent with the predictions of the Ancestral Shape Hypothesis. Several vertebral traits were associated with disc herniation, including a vertebral body that is both more circular and more ventrally wedged, relatively short pedicles and laminae, relatively long, more cranio-laterally projecting transverse processes, and relatively long, cranially-oriented spinous processes. We found that there are biomechanical and comparative anatomical reasons for suspecting that all of these traits are capable of predisposing individuals to intervertebral disc herniation. Conclusions The results of the present study add weight to the hypothesis that intervertebral disc herniation in H. sapiens is connected with vertebral shape. Specifically, they suggest that individuals whose vertebrae are towards the ancestral end of the range of shape variation within H. sapiens have a greater propensity to develop the condition than other individuals. More generally, the study shows that evolutionary thinking has the potential to shed new light on human skeletal pathologies.

scholarly journals Spinopelvic alignment and lumbar vertebral shape in children: associations with structural spinal abnormalities and body composition in the generation R study

2021 ◽  
Author(s):  
Marleen M. van den Heuvel ◽  
Nathalie E. Griffioen ◽  
Hakim C. Achterberg ◽  
Edwin H. G. Oei ◽  
Jeroen J. M. Renkens ◽  
...  
Keyword(s):  
Body Composition ◽  
Pelvic Incidence ◽  
Lumbar Vertebrae ◽  
Fat Free Mass ◽  
Disc Height ◽  
Multilevel Regression ◽  
Cross Sectional ◽  
Spinopelvic Alignment ◽  
The Mean ◽  
Vertebral Shape

Abstract Purpose To investigate the spinopelvic alignment and vertebral shape in children, and associations with body composition and structural spinal abnormalities on magnetic resonance imaging (MRI). Methods We performed a cross-sectional study embedded in the Generation R Study, a prospective population-based birth cohort. Pelvic incidence and vertebral concavity ratios for each lumbar level were determined on sagittal MRI images in 9-year-old children, and structural spinal abnormalities were scored semi-quantitatively. The BMI-SD score was calculated, and body composition was assessed using DXA scans. Associations of pelvic incidence and vertebral concavity ratios with structural abnormalities and body composition measures were assessed using (multilevel) regression analyses. Results This study included 522 participants (47.7% boys), aged 9.9 years (IQR 9.7–10.0). The mean pelvic incidence was 36.6° (SD 8.0). Vertebral concavity ratios ranged from 0.87 to 0.90, with significantly lower ratios for boys compared to girls. Associations were found for a larger pelvic incidence with decreased disc height [OR 1.03 (95% CI 1.02–1.05)], and a pelvic incidence in the lowest tertile with less disc bulging [OR 0.73 (95% CI 0.56–0.95)]. Increased vertebral concavity ratio was associated with decreased disc height [OR 14.16 (95% CI 1.28–157.13)]. Finally, increased fat-free mass index was associated with a smaller pelvic incidence [adjusted OR 0.85 (95% CI 0.07–1.63)]. Conclusion The mean pelvic incidence of 9-year-old children is 36.6° on supine MRI images, and a slightly concave shape of the lumbar vertebrae is seen. Spinopelvic alignment is associated with structural spinal abnormalities, and might itself be influenced by the children’s body composition.

scholarly journals Periodic catastrophes over human evolutionary history are necessary to explain the forager population paradox

2019 ◽  
Vol 116 (26) ◽  
pp. 12758-12766 ◽  
Author(s):  
Michael D. Gurven ◽  
Raziel J. Davison
Keyword(s):  
Evolutionary History ◽  
Homo Sapiens ◽  
Vital Rate ◽  
Small Scale ◽  
Human Populations ◽  
Wild Chimpanzee ◽  
Population Fluctuations ◽  
Vital Rates ◽  
Zero Population Growth ◽  
Major Adjustment

The rapid growth of contemporary human foragers and steady decline of chimpanzees represent puzzling population paradoxes, as any species must exhibit near-stationary growth over much of their evolutionary history. We evaluate the conditions favoring zero population growth (ZPG) among 10 small-scale subsistence human populations and five wild chimpanzee groups according to four demographic scenarios: altered mean vital rates (i.e., fertility and mortality), vital rate stochasticity, vital rate covariance, and periodic catastrophes. Among most human populations, changing mean fertility or survivorship alone requires unprecedented alterations. Stochastic variance and covariance would similarly require major adjustment to achieve ZPG in most populations. Crashes could maintain ZPG in slow-growing populations but must be frequent and severe in fast-growing populations—more extreme than observed in the ethnographic record. A combination of vital rate alteration with catastrophes is the most realistic solution to the forager population paradox. ZPG in declining chimpanzees is more readily obtainable through reducing mortality and altering covariance. While some human populations may have hovered near ZPG under harsher conditions (e.g., violence or food shortage), modernHomo sapienswere equipped with the potential to rapidly colonize new habitats and likely experienced population fluctuations and local extinctions over evolutionary history.

scholarly journals Influence of mass on tarsus shape variation: a morphometrical investigation among Rhinocerotidae (Mammalia: Perissodactyla)

2020 ◽  
Vol 129 (4) ◽  
pp. 950-974 ◽  
Author(s):  
Cyril Etienne ◽  
Christophe Mallet ◽  
Raphaël Cornette ◽  
Alexandra Houssaye
Keyword(s):  
Body Weight ◽  
Body Mass ◽  
Evolutionary History ◽  
The Body ◽  
The Other ◽  
Upright Posture ◽  
Centroid Size ◽  
Shape Variation ◽  
Morphological Adaptations ◽  
Both Bones

Abstract Many tetrapod lineages show extreme increases in body mass in their evolutionary history, associated with important osteological changes. The ankle joint, essential for foot movement, is assumed to be particularly affected in this regard. We investigated the morphological adaptations of the astragalus and the calcaneus in Rhinocerotidae, and analysed them in light of a comparative analysis with other Perissodactyla. We performed 3D geometric morphometrics and correlated shape with centroid size of the bone and body mass of the species. Our results show that mass has an influence on bone shape in Rhinocerotidae and in Perissodactyla, but this is not as strong as expected. In heavy animals the astragalus has a flatter trochlea, orientated more proximally, associated with a more upright posture of the limb. The calcaneus is more robust, possibly to sustain the greater tension force exerted by the muscles during plantarflexion. Both bones show wider articular facets, providing greater cohesion and better dissipation of the loading forces. The body plan of the animals also has an influence. Short-legged Teleoceratina have a flatter astragalus than the other rhinocerotids. Paraceratherium has a thinner calcaneus than expected. This study clarifies adaptations to high body weight among Rhinocerotidae and calls for similar investigations in other groups with massive forms.

Mammals: A Very Short Introduction

2017 ◽  
Author(s):  
T. S. Kemp
Keyword(s):  
Fossil Record ◽  
Evolutionary History ◽  
Homo Sapiens ◽  
Short Introduction ◽  
Large Brain ◽  
Modes Of Life ◽  
Huge Variety

Mammals: A Very Short Introduction explores the nature, evolutionary history, and modern diversity of mammals. From a little shrew-like, nocturnal, insect-eating ancestor living 200 million years ago (mya), mammals have evolved into a huge variety of different kinds of animals. This VSI explains how it is endothermy—‘warm-bloodedness’—enabling high levels of activity and the relatively large brain associated with complex, adaptable behaviour that epitomizes mammals. It describes their remarkable fossil record, revealing how and when the mammals gained their characteristics, and the tortuous course of their evolution. It reveals the adaptations mammals evolved to suit their varied modes of life, including those of mainly arboreal primates culminating in Homo sapiens.

Human Evolution

1984 ◽  
Vol 8 ◽  
pp. 182-198
Author(s):  
Catherine Badgley
Keyword(s):  
Human Evolution ◽  
Evolutionary History ◽  
Pan Paniscus ◽  
Homo Sapiens ◽  
Great Apes ◽  
Sister Group ◽  
The Family ◽  
History Of ◽  
Living Species ◽  
Single Living

The evolutionary history of humans is well understood in outline, compared to that of many other groups of mammals. But human evolution remains enigmatic in its details, and these are compelling both scientifically and personally because they relate to the biological uniqueness of humans. Humans are placed in the primate family Hominidae, which, in traditional classifications, contains a single living species, Homo sapiens. The closest living relatives of humans are great apes: the chimpanzees Pan paniscus and Pan troglodytes, the gorilla Gorilla gorilla, and the orangutan Pongo pygmaeus. These apes have traditionally been placed in the family Pongidae as the sister group of Hominidae. Living Hominidae and Pongidae, together with Hylobatidae (gibbons) comprise the modern representatives of the primate suborder Hominoidea.

scholarly journals The evolution of the human pelvis: changing adaptations to bipedalism, obstetrics and thermoregulation

2015 ◽  
Vol 370 (1663) ◽  
pp. 20140063 ◽  
Author(s):  
Laura Tobias Gruss ◽  
Daniel Schmitt
Keyword(s):  
Evolutionary History ◽  
Heat Dissipation ◽  
Homo Sapiens ◽  
Brain Size ◽  
Major Change ◽  
Habitat Diversity ◽  
Bipedal Walking ◽  
Birth Canal ◽  
Selective Pressures ◽  
Hominin Evolution

The fossil record of the human pelvis reveals the selective priorities acting on hominin anatomy at different points in our evolutionary history, during which mechanical requirements for locomotion, childbirth and thermoregulation often conflicted. In our earliest upright ancestors, fundamental alterations of the pelvis compared with non-human primates facilitated bipedal walking. Further changes early in hominin evolution produced a platypelloid birth canal in a pelvis that was wide overall, with flaring ilia. This pelvic form was maintained over 3–4 Myr with only moderate changes in response to greater habitat diversity, changes in locomotor behaviour and increases in brain size. It was not until Homo sapiens evolved in Africa and the Middle East 200 000 years ago that the narrow anatomically modern pelvis with a more circular birth canal emerged. This major change appears to reflect selective pressures for further increases in neonatal brain size and for a narrow body shape associated with heat dissipation in warm environments. The advent of the modern birth canal, the shape and alignment of which require fetal rotation during birth, allowed the earliest members of our species to deal obstetrically with increases in encephalization while maintaining a narrow body to meet thermoregulatory demands and enhance locomotor performance.

scholarly journals A distinct expression profile in the cerebellum and striatum for genes under selection within introgression deserts

2021 ◽  
Author(s):  
Raul Buisan ◽  
Juan Moriano ◽  
Alejandro Andirko ◽  
Cedric Boeckx
Keyword(s):  
Positive Selection ◽  
Evolutionary History ◽  
Developmental Stages ◽  
Homo Sapiens ◽  
Transcriptomic Data ◽  
Functional Differences ◽  
History Of ◽  
Genomic Regions ◽  
Cerebral Neocortex

Analyses of ancient DNA from extinct hominins have provided unique insights into the complex evolutionary history of Homo sapiens, intricately related to that of the Neanderthals and the Denisovans as revealed by several instances of admixture events. These analyses have also allowed the identification of introgression deserts: genomic regions in our species that are depleted of `archaic' haplotypes. The presence of genes like FOXP2 in these deserts has been taken to be suggestive of brain-related functional differences between Homo species. Here, we seek a deeper characterization of these regions, taking into account signals of positive selection in our lineage. Analyzing publicly available transcriptomic data from the human brain at different developmental stages, we found that structures outside the cerebral neocortex, and especially the cerebellum and the striatum at prenatal stages, show the most divergent transcriptomic profiles when considering genes under positive selection within introgression deserts.

scholarly journals Current Progress in Evolutionary Comparative Genomics of Great Apes

2021 ◽  
Vol 12 ◽  
Author(s):  
Aisha Yousaf ◽  
Junfeng Liu ◽  
Sicheng Ye ◽  
Hua Chen
Keyword(s):  
Evolutionary History ◽  
Comparative Genomic ◽  
Great Ape ◽  
Structural Variations ◽  
Genome Sequences ◽  
New Genes ◽  
Genomic Analyses ◽  
Genomic Studies ◽  
High Quality Genome ◽  
Human Specific

The availability of high-quality genome sequences of great ape species provides unprecedented opportunities for genomic analyses. Herein, we reviewed the recent progress in evolutionary comparative genomic studies of the existing great ape species, including human, chimpanzee, bonobo, gorilla, and orangutan. We elaborate discovery on evolutionary history, natural selection, structural variations, and new genes of these species, which is informative for understanding the origin of human-specific phenotypes.

Why Faces May Be Special: Evidence of the Inversion Effect in Chimpanzees

1998 ◽  
Vol 10 (5) ◽  
pp. 615-622 ◽  
Author(s):  
Lisa A. Parr ◽  
Tara Dove ◽  
William D. Hopkins
Keyword(s):  
Pan Troglodytes ◽  
Homo Sapiens ◽  
Inversion Effect ◽  
Matching To Sample ◽  
Great Ape ◽  
Black And White ◽  
The Face ◽  
Face Stimuli ◽  
Human Faces ◽  
Sequential Matching

Five chimpanzees were tested on their ability to discriminate faces and automobiles presented in both their upright and inverted orientations. The face stimuli consisted of 30 black and white photographs, 10 each of unfamiliar chimpanzees (Pan troglodytes), brown capuchins (Cebus apella), and humans (Homo sapiens). Ten black and white photographs of automobiles were also used. The stimuli were presented in a sequential matching-to-sample (SMTS) format using a computerized joystick-testing apparatus. Subjects performed better on upright than inverted stimuli in all classes. Performance was significantly better on upright than inverted presentations of chimpanzee and human faces but not on capuchin monkey faces or automobiles. These data support previous studies in humans that suggest the inversion effect occurs for stimuli for which subjects have developed an expertise. Alternative explanations for the inversion effect based on the type of spatial frequency contained in the stimuli are also discussed. These data are the first to provide evidence for the inversion effect using several classes of face stimuli in a great ape species.

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