Fetal load and the evolution of lumbar lordosis in bipedal hominins

  title={Fetal load and the evolution of lumbar lordosis in bipedal hominins},
  author={Katherine K Whitcome and Liza J Shapiro and Daniel E. Lieberman},
As predicted by Darwin, bipedal posture and locomotion are key distinguishing features of the earliest known hominins. Hominin axial skeletons show many derived adaptations for bipedalism, including an elongated lumbar region, both in the number of vertebrae and their lengths, as well as a marked posterior concavity of wedged lumbar vertebrae, known as a lordosis. The lordosis stabilizes the upper body over the lower limbs in bipeds by positioning the trunk’s centre of mass (COM) above the hips… 

Inferring lumbar lordosis in Neandertals and other hominins

Although Neandertals demonstrate more bony kyphotic wedging than most modern humans, this work cast doubt on proposed locomotor and postural differences between the two lineages based on inferred lumbar lordosis (or lack thereof), and recommends future research compare fossils to modern humans from varied populations and not just recent, postindustrial samples.

Lumbar lordosis of extinct hominins.

The assumption that human-like lordotic curvature was a morphological change that took place during the acquisition of erect posture and bipedalism as the habitual form of locomotion is confirmed.

Functional implications of variation in lumbar vertebral count among hominins.

The cervical spine of Australopithecus sediba.

Vertebral Morphology in Hominoids II: The Lumbar Spine

Comparative research on nonhominoid primates and other mammals support that hominoid lumbar features confer axial stability in a variety of positional behaviors, while studies of experimental biomechanics have revealed more rotational capabilities in thehominoid trunk than previously thought, and analyses of back musculature offer new information about fiber-type differences between hominoids and other primates.

The Evolution and Function of Human Lumbar Lordosis Variability

The biomechanical consequences of lordosis variability in modern humans in three studies are explored to understand the evolutionary pressures that have shaped the human lumbar spine and provide context for interpreting lordosis in fossil hominins and shed light on the etiology of modern lumbr spinal pathology.

Evolution of the hominoid vertebral column: The long and the short of it

An overview of what is known about evolution of the hominoid vertebral column is provided, focusing on the currently available anatomical evidence of three major transitions: tail loss and adaptations to orthograde posture and bipedal locomotion.

Placement of the diaphragmatic vertebra in catarrhines: implications for the evolution of dorsostability in hominoids and bipedalism in hominins.

A scenario of hominin evolution is proposed in which early hominins evolved cranial displacement from the ancestral hominid condition of common placement to achieve effective lumbar lordosis during the evolution of bipedal locomotion.

The Association Between Spinal Posture and Spinal Biomechanics in Modern Humans: Implications for Extinct Hominins

The main findings indicate that each group/lineage of hominins had special biomechanical characteristics, and Homo sapiens and Homo erectus with moderate to high spinal curvatures, similar to the posture of modern humans, probably had similar spinal biomechanicals characteristics as modern humans.

Spinal lordosis optimizes the requirements for a stable erect posture

The development of a spinal lordosis is a compromise between the stability requirements of an erect posture and the necessity of torque equilibria at each spinal segment.



Endurance running and the evolution of Homo

Judged by several criteria, humans perform remarkably well at endurance running, thanks to a diverse array of features, many of which leave traces in the skeleton.

Comparative morphometric study of the australopithecine vertebral series Stw-H8/H41.

Detailed description and comparative morphometric analysis of the australopithecine thoracolumbar vertebral series Stw-H8/H41 and examines spinal mechanics in early hominids confirm that the morphology of the lower spine in australipithecines has no modern analogue in its entirety.

Postcranial adaptation in nonhuman primates

Postcranial Adaptation in Nonhuman Primates is devoted to problems in primate functional morphology and provides a useful review of the literature on each topic.

Transmission of weight through the lower thoracic and lumbar regions of the vertebral column in man.

This study suggests that a considerable part of the weight of the upper limbs and the thoracic cage is transmitted through the ribs to the posterior column (laminae) through the costo-transverse articulations and ligaments.

The comparative morphology of the vertebrate spinal column. Its form as related to function

The form of the vertebral column is definitely related to its function as a supporting rod, a base for attachment of body and limb muscles, and a protection of the spinal cord and nerves. Primitively

Virtual cranial reconstruction of Sahelanthropus tchadensis

A detailed virtual reconstruction of the TM 266 cranium confirms that S. tchadensis is a hominid and is not more closely related to the African great apes, and indicates that bipedalism was present in the earliest known hominids, and probably arose soon after the divergence of the chimpanzee and human lineages.

External and Internal Morphology of the BAR 1002'00 Orrorin tugenensis Femur

Computerized tomography scans of the neck-shaft junction of BAR 1002′00 reveal that the cortex is markedly thinner superiorly than inferiorly, differing from the approximately equal cortical thicknesses observed in extant African apes, approaching the condition in later hominids, and indicating that O. tugenensis was bipedal.

Primate locomotion : recent advances

This book discusses naturalistic Behavior, Morphology and Behavior, Fossils and Reconstructing the Origins and Evolution of Taxa, and Data Acquisition and Analytic Techniques.

Erector spinae lever arm length variations with changes in spinal curvature.

There was a considerable effect (10-24%) of lumbar curvature on lever arm lengths for the back extensor muscles in lordosis, which will affect the need for extensor muscle force and thus the magnitude of compression in theLumbar spine in loading situations such as lifting.