An Evolutionary Perspective of Spinal Pathology and Spinal Health

Humans are the only living hominoid that habitually stands upright and walks on two legs. The adoption of an erect posture as habitual imposed substantial changes on spinal morphology and biomechanics. One of the major morphological changes is the increased curvatures found in the human spine. There is an ongoing debate about whether humans “pay” for becoming bipedal by suffering from a high prevalence of back pain and spinal pathology. To answer this question, we explored the relationship between sagittal spinal posture and spinal pathologies, back pain, and health-related quality of life. We found that spinal posture closely correlates with spinal pathology. Individuals with a well-aligned spine – within the neutral zone defined as moderate spinal curvatures and the line of gravity close to the acetabulum – have a better quality of life, less back pain, and less spinal pathology. Individuals out of the neutral zone, with accentuated or with decreased pelvic incidence and spinal curvatures, are at a higher risk for developing spinal pathology, back pain, and reduced quality of life. Moreover, we found that spinal pathologies such as spondylolysis and spondylolisthesis are associated with the accentuated human morphology (higher pelvic incidence and lumbar lordosis), in accordance with the “overshoot theory”. At the same time, other pathologies such as disc herniation and Schmorl nodes are associate with the decreased human morphology (low pelvic incidence and hypolordosis), in accordance with the “undershoot theory”.

If indeed evolution is a major contributor to spinal pathology, then we should also seek solutions to these problems considering evolution. Evolutionarily, the human body is built for bipedal walking. When compared to other mammals, the human gait is very efficient as it requires very little energy to move the body forward. In the paleoanthropological and archeological records, there is strong evidence to suggest that humans walked long distances as part of their habitual behaviors. Biomechanically, the human spine experiences a gentle rotational movement of the lower back while walking, together with mild oscillations of compression and distraction between adjunct vertebrae. Research suggests that mild exercise is beneficial for alleviating chronic low back pain. In this paper, we would like to argue that from an evolutionary point of view, walking should be one of the best exercises for low back pain.