A Backache of Longstanding: An Evolutionary Perspective on the Human Vertebral Column

Humans walk in a most peculiar way – on our extended hind limbs. No other mammal walks in this fashion and as far as we know no other mammal, save our immediate ancestors, has even experimented with this unusual form of walking.  The biomechanical requirements necessary to accomplish habitual bipedality have led to dramatic changes in the human musculoskeleton.   Included among these anatomical adaptations are the myriad skeletal and soft tissue modifications in the human vertebral column.   The human vertebral column is unique in its sinusoidal curvatures that allow the upper body to balance over the hips. However, in turning a spine originally adapted for a quadruped into one that is perpendicular to the ground has resulted in numerous problems that are unique to our species. Included in such uniquely human maladies are spondylolysis, spondylolosthesis, herniated discs, spontaneously fractured vertebrae, kyphosis, and scoliosis. An evolutionary perspective sheds light on why we remain uniquely vulnerable to such a wide range of spinal disorders.